Science.gov

Sample records for fe model part

  1. A Structural Molar Volume Model for Oxide Melts Part III: Fe Oxide-Containing Melts

    NASA Astrophysics Data System (ADS)

    Thibodeau, Eric; Gheribi, Aimen E.; Jung, In-Ho

    2016-04-01

    As part III of this series, the model is extended to iron oxide-containing melts. All available experimental data in the FeO-Fe2O3-Na2O-K2O-MgO-CaO-MnO-Al2O3-SiO2 system were critically evaluated based on the experimental condition. The variations of FeO and Fe2O3 in the melts were taken into account by using FactSage to calculate the Fe2+/Fe3+ distribution. The molar volume model with unary and binary model parameters can be used to predict the molar volume of the molten oxide of the Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-FeO-Fe2O3-Al2O3-SiO2 system in the entire range of compositions, temperatures, and oxygen partial pressures from Fe saturation to 1 atm pressure.

  2. Modeling of viscosities of the partly crystallized slags in the Al2O3-CaO-``FeO''-SiO2 system

    NASA Astrophysics Data System (ADS)

    Kondratiev, Alex; Jak, Evgueni

    2001-12-01

    A viscosity model of the partly crystallized slag in the Al2O3-CaO-‘FeO’-SiO2 system has been developed in conjunction with the thermodynamic computer package F*A*C*T. Proportions of solids crystallized out of the liquid phase and compositions of the remaining liquid phase predicted by F*A*C*T are used in the viscosity model. Various heterogeneous viscosity models have been tested using large experimental dataset in the Al2O3-CaO-‘FeO’-SiO2 system in reducing conditions close to the equilibrium with metallic iron. The Roscoe equation with new empirical parameters was found to provide reasonable agreement with experimental data. Examples of model application to industrial nonferrous smelting slag systems are presented. This model can also be applied to coal ash slags.

  3. Model Fe-Al Steel with Exceptional Resistance to High Temperature Coarsening. Part I: Coarsening Mechanism and Particle Pinning Effects

    NASA Astrophysics Data System (ADS)

    Zhou, Tihe; Zurob, Hatem S.; O'Malley, Ronald J.; Rehman, Kashif

    2015-01-01

    The mechanism by which austenite particles coarsen in a delta-ferrite matrix was investigated in a model Al-containing steel. Special emphasis was placed on the effect of volume fraction on the coarsening kinetics as well as the ability of the particles to pin the growth of delta-ferrite grains. The specimens were heated to temperatures in the range of 1123 K to 1583 K (850 °C to 1305 °C) in the austenite plus delta-ferrite two-phase region and held for times between 5 minutes and 288 hours, followed by water quenching. When the reheating temperature was higher than 1473 K (1200 °C), the coarsening of austenite particles was found to evolve as t 1/3, which is typical of volume diffusion-controlled behavior. For lower temperatures, the particle coarsening behavior followed t 1/4 kinetics which is consistent with a grain boundary diffusion-controlled process. The observations were interpreted in terms of the modified Lifshitz-Slyozov-Wanger theory by considering multi-component diffusion, particle volume fraction, and the fact that this two-phase material is a non-ideal solid solution. Three types of interaction between particle coarsening and grain growth were observed. Grain growth was completely pinned when the particle pinning force was much larger than the driving force for grain growth. When the particle pinning force was comparable to the driving force for grain growth, the delta-ferrite grains were observed to grow at a rate which is controlled by the kinetics of coarsening of the austenite particles. Finally, when the particle pinning force was smaller than the driving force for grain growth, significant grain growth occurred but its rate was lower than that expected in the absence of particle pinning. The results point to an effective approach for controlling grain growth at high temperatures.

  4. A thermodynamic model of nickel smelting and direct high-grade nickel matte smelting processes: Part II. distribution behaviors of Ni, Cu, Co, Fe, As, Sb, and Bi

    NASA Astrophysics Data System (ADS)

    Tan, Pengfu; Neuschütz, Dieter

    2001-04-01

    A thermodynamic model has been developed to predict the distribution behavior of Ni, Cu, Co, Fe, S, As, Sb, and Bi in nickel smelting and direct high-grade nickel matte smelting processes. The model has been validated by numerous experimental data and industrial data with a wide range of operating conditions. The effect of operating conditions on the distributions of Ni, Cu, Co, As, Sb, and Bi among the gas, matte, and slag phases has been investigated. It was found that the distribution behavior of Ni, Co, Cu, As, Sb, and Bi in the nickel smelting furnace depends on process parameters such as the smelting temperature, matte grade, oxygen enrichment, Fe/SiO2 ratio in the slag, Cu/Ni ratio in charge, and oil/air ratio. The parameters also have an influence on the behavior of Fe3O4 in the slag.

  5. Aluminum Deoxidation Equilibria in Liquid Iron: Part III—Experiments and Thermodynamic Modeling of the Fe-Mn-Al-O System

    NASA Astrophysics Data System (ADS)

    Paek, Min-Kyu; Do, Kyung-Hyo; Kang, Youn-Bae; Jung, In-Ho; Pak, Jong-Jin

    2016-06-01

    Deoxidation equilibria in high-Mn- and high-Al-alloyed liquid steels were studied over the entire Fe-Mn-Al composition range by both experiments and thermodynamic modeling. Effect of Mn on the Al deoxidation equilibria in liquid iron was measured by the different experimental techniques depending on the Al content. In order to confirm the reproducibility of the experimental results, the deoxidation experiments were carried out reversibly from high oxygen state by addition of Al as a deoxidizer, and from low oxygen state by addition of Fe2O3 or MnO as an oxygen source. For the Al-rich side, CaO flux was added on top of liquid iron in order to remove suspended Al2O3 inclusions in the melt. Based on the present experimental result and available critically evaluated literature data, the Al deoxidation equilibria in Fe-Mn-Al-O liquid alloy were thermodynamically modeled. The Modified Quasichemical Model was used in order to take into account a strong short-range ordering of atoms in molten state. Deoxidation equilibria and inclusion stability diagram for entire Fe-Mn-Al melt were successfully reproduced by the present model.

  6. Numerical Simulation of Three-Dimensional Dendritic Growth of Alloy: Part II—Model Application to Fe-0.82WtPctC Alloy

    NASA Astrophysics Data System (ADS)

    Wang, Weiling; Luo, Sen; Zhu, Miaoyong

    2016-03-01

    In the second part (Part II) of the present simulation work, the three-dimensional (3D) dendritic growth of Fe-0.82wtpctC alloy is investigated with the 3D CA-FVM cellular automaton-finite volume method model developed in Part I. The influences of the melt undercooling, the interfacial anisotropy, and the forced flow on the equiaxed dendritic growth, especially the formation of secondary arms, are discussed. The comparisons of equiaxed dendritic growth in 3D and two-dimensional (2D) are also carried out. Finally, the columnar dendritic growth under different cooling conditions is investigated including the morphology and the secondary dendrite arm spacing (SDAS). The results show that the high undercooling can promote the formation of secondary arms as the anisotropy parameter is 0.04. With the increase of the anisotropy parameter, the secondary arms first reduce and then well develop again; meanwhile the tertiary arms are gradually developed. However, the secondary arms vanish at the undercooling of 5 K as the anisotropy parameter increases to 0.04. With the introduction of the forced flow with the inlet velocity of 0.001 m/s along the x axis, the secondary arms at the left (upstream) arm become more developed. However, they become slightly less developed with the forced flow intensifying. Secondary arms at the left side (upstream) of the perpendicular arms and in the y-z symmetrical plane become more and more developed as the inlet velocity increases. The competition of the secondary arms at the right side (downstream) of the perpendicular arms and at the right (downstream) arm becomes significant as the undercooling increases from 10 to 15 K. The solute-enriched envelope in 2D is much thicker than in the 3D case, so that the dendritic growth in 2D is influenced more by the melt flow and the undercooling; moreover, the secondary arms in 2D are hard to form even at the undercooling of 15 K and with the forced convection in the present article. Meanwhile, the

  7. Modeling equilibrium Fe isotope fractionation

    NASA Astrophysics Data System (ADS)

    Anbar, A.; Jarzecki, A.; Spiro, T.

    2003-04-01

    Research into the stable isotope biogeochemistry of Fe and other transition metals has been driven primarily by analytical innovations which have revealed significant isotope effects in nature and the laboratory. Further development of these new isotope systems requires complementary theoretical research to guide analytical efforts. The results of the first such studies show some discrepancies with experiments. For example, Johnson et al. (2002) report an experimentally-determined 56Fe/54Fe equilibrium fractionation factor between Fe(II) and Fe(III) aquo complexes of ˜1.0025. This effect is ˜50% smaller than predicted theoretically by Schauble et al. (2001). It is important to resolve such discrepancies. Equilibrium isotope fractionation factors can be predicted from vibrational spectroscopic data of isotopically-substituted complexes, or from theoretical predictions of some or all of these frequencies obtained using force field models. The pioneering work of Schauble et al. (2001) utilized a modified Urey-Bradley force field (MUBFF) model. This approach is limiting in at least three ways: First, it is not ab initio, requiring as input some measured vibrational frequencies. Such data are not always available, or may have significant uncertainties. Second, the MUBFF does not include potentially important effects of solvent interaction. Third, because it makes certain assumptions about molecular symmetry, the MUBFF-based approach is not able to model the spectra of mixed-ligand complexes. To address these limitations, we are evaluating the use of density functional theory (DFT) as an ab initio method to predict vibrational frequencies of isotopically-substituted complexes and, hence, equilibrium fractionation factors. In a preliminary examination of the frequency shift upon isotope substitution of the bending and asymmetric stretching modes of the tetrahedral FeCl_42- complex, we find substantial differences between MUBFF and DFT predictions. Results for other Fe

  8. A Functional Model of [Fe]-Hydrogenase.

    PubMed

    Xu, Tao; Yin, Chih-Juo Madeline; Wodrich, Matthew D; Mazza, Simona; Schultz, Katherine M; Scopelliti, Rosario; Hu, Xile

    2016-03-16

    [Fe]-Hydrogenase catalyzes the hydrogenation of a biological substrate via the heterolytic splitting of molecular hydrogen. While many synthetic models of [Fe]-hydrogenase have been prepared, none yet are capable of activating H2 on their own. Here, we report the first Fe-based functional mimic of the active site of [Fe]-hydrogenase, which was developed based on a mechanistic understanding. The activity of this iron model complex is enabled by its unique ligand environment, consisting of biomimetic pyridinylacyl and carbonyl ligands, as well as a bioinspired diphosphine ligand with a pendant amine moiety. The model complex activates H2 and mediates hydrogenation of an aldehyde. PMID:26926708

  9. Models, Part IV: Inquiry Models.

    ERIC Educational Resources Information Center

    Callison, Daniel

    2002-01-01

    Discusses models for information skills that include inquiry-oriented activities. Highlights include WebQuest, which uses Internet resources supplemented with videoconferencing; Minnesota's Inquiry Process based on the Big Six model for information problem-solving; Indiana's Student Inquiry Model; constructivist learning models for inquiry; and…

  10. Reinvestigation of the Fe-rich part of the pseudo-binary system SrO-Fe{sub 2}O{sub 3}

    SciTech Connect

    Langhof, N.; Seifert, D.; Goebbels, M.; Toepfer, J.

    2009-09-15

    The phase relations in the Fe-rich part of the pseudo-binary system SrO-Fe{sub 2}O{sub 3} (>33 mol% Fe{sub 2}O{sub 3}) were reinvestigated between 800 and 1500 deg. C in air. A combination of microscopy, electron probe micro-analysis, powder X-ray diffraction and thermal analysis was used to determine phase relations, crystal structure parameters and phase transition temperatures. M-type hexagonal ferrite SrFe{sub 12}O{sub 19} (85.71 mol% Fe{sub 2}O{sub 3}) is stable up to 1410 deg. C. No indication of a significant phase width was found; Sr{sub 4}Fe{sub 6}O{sub 13+}-{sub {delta}} appears as a second phase in compositions with <85.71+-0.2 mol% Fe{sub 2}O{sub 3}. Sr{sub 4}Fe{sub 6}O{sub 13+}-{sub {delta}} itself is stable between 800 and 1250 deg. C. Two other hexagonal ferrites were found to exist at high temperatures only: W-type SrFe{sup 2+}{sub 2}Fe{sup 3+}{sub 16}O{sub 27} is stable between 1350 and 1440 deg. C and X-type ferrite Sr{sub 2}Fe{sup 2+}{sub 2}Fe{sup 3+}{sub 28}O{sub 46} between 1350 and 1420 deg. C, respectively, which is shown here for the first time. These findings in combination with previously published data were used to derive a corrected phase diagram of the Fe-rich part of the pseudo-binary system SrO-Fe{sub 2}O{sub 3}. - Abstract: Part of the SrO-Fe{sub 2}O{sub 3} phase diagram in air

  11. Modeling the Reaction of Fe Atoms with CCl4

    SciTech Connect

    Camaioni, Donald M.; Ginovska, Bojana; Dupuis, Michel

    2009-01-05

    The reaction of zero-valent iron with carbon tetrachloride (CCl4) in gas phase was studied using density functional theory. Temperature programmed desorption experiments over a range of Fe and CCl4 coverages on a FeO(111) surface, demonstrate a rich surface chemistry with several reaction products (C2Cl4, C2Cl6, OCCl2, CO, FeCl2, FeCl3) observed. The reactivity of Fe and CCl4 was studied under three stoichiometries, one Fe with one CCl4, one Fe with two CCl4 molecules and two Fe with one CCl4, modeling the environment of the experimental work. The electronic structure calculations give insight into the reactions leading to the experimentally observed products and suggest that novel Fe-C-Cl containing species are important intermediates in these reactions. The intermediate complexes are formed in highly exothermic reactions, in agreement with the experimentally observed reactivity with the surface at low temperature (30 K). This initial survey of the reactivity of Fe with CCl4 identifies some potential reaction pathways that are important in the effort to use Fe nano-particles to differentiate harmful pathways that lead to the formation of contaminants like chloroform (CHCl3) from harmless pathways that lead to products such as formate (HCO2-) or carbon oxides in water and soil. The Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

  12. Hydrodynamic Modelling and Experimental Analysis of FE-DMFC Stacks

    NASA Astrophysics Data System (ADS)

    Kablou, Yashar

    Direct methanol fuel cells (DMFCs) present some unique features such as having liquid fuel, quick refueling process, compact design and high energy density. These characteristics make them incredibly suitable as a promising power source for portable electronic applications, such as cell phones or laptop computers. Despite of these positive aspects, the commercial development of DMFCs has nevertheless been hindered by some important issues such as, carbon dioxide formation at the anode compartment and, methanol crossover through the membrane. Many researchers have tried to model the two-phase flow behavior inside the DMFC anode compartment using the "homogenous flow modelling" approach, which has proven to be inaccurate specially when dealing with DMFC stacks. On the other hand, several strategies to prevent methanol crossover have been suggested in the literature, including the use of a flowing electrolyte between the DMFC anode and cathode compartments. Preliminary tests on flowing electrolyte direct methanol fuel cells (FE-DMFCs) have shown promising results; however, further investigation should be carried out on the stack level. In the first part of this study, a quasi two-dimensional numerical model was developed, to predict the two-phase flow behavior within the DMFC anode compartment, both in single cell and stack levels. Various types of flow modelling approaches and void fraction correlations were utilized to estimate the pressure drop across the anode compartment. It was found that the "separated flow modelling" approach, as well as CISE correlation for void fraction (developed at the CISE labs in Milan), yield the best results. In the second part, a five-cell FE-DMFC stack unit with a parallel serpentine flow bed design and U-type manifold configuration, was developed and tested at various operating conditions. It was found that, the flowing electrolyte effectively reduced methanol crossover and, improved the stack performance.

  13. Solution-phase photochemistry of a [FeFe]hydrogenase model compound: Evidence of photoinduced isomerisation

    SciTech Connect

    Kania, Rafal; Hunt, Neil T.; Frederix, Pim W. J. M.; Wright, Joseph A.; Pickett, Christopher J.; Ulijn, Rein V.

    2012-01-28

    The solution-phase photochemistry of the [FeFe] hydrogenase subsite model ({mu}-S(CH{sub 2}){sub 3}S)Fe{sub 2}(CO){sub 4}(PMe{sub 3}){sub 2} has been studied using ultrafast time-resolved infrared spectroscopy supported by density functional theory calculations. In three different solvents, n-heptane, methanol, and acetonitrile, relaxation of the tricarbonyl intermediate formed by UV photolysis of a carbonyl ligand leads to geminate recombination with a bias towards a thermodynamically less stable isomeric form, suggesting that facile interconversion of the ligand groups at the Fe center is possible in the unsaturated species. In a polar or hydrogen bonding solvent, this process competes with solvent substitution leading to the formation of stable solvent adduct species. The data provide further insight into the effect of incorporating non-carbonyl ligands on the dynamics and photochemistry of hydrogenase-derived biomimetic compounds.

  14. Comparison of Ab initio Low-Energy Models for LaFePO, LaFeAsO, BaFe2As2, LiFeAs, FeSe, and FeTe: Electron Correlation and Covalency

    NASA Astrophysics Data System (ADS)

    Miyake, Takashi; Nakamura, Kazuma; Arita, Ryotaro; Imada, Masatoshi

    2010-04-01

    Effective low-energy Hamiltonians for several different families of iron-based superconductors are compared after deriving them from the downfolding scheme based on first-principles calculations. Systematic dependences of the derived model parameters on the families are elucidated, many of which are understood from the systematic variation of the covalency between Fe-3d and pnictogen-/chalcogen-p orbitals. First, LaFePO, LaFeAsO (1111), BaFe2As2 (122), LiFeAs (111), FeSe, and FeTe (11) have overall similar band structures near the Fermi level, where the total widths of 10-fold Fe-3d bands are mostly around 4.5 eV. However, the derived effective models of the 10-fold Fe-3d bands (d model) for FeSe and FeTe have substantially larger effective onsite Coulomb interactions U˜ 4.2 and 3.4 eV, respectively, after the screening by electrons on other bands and after averaging over orbitals, as compared to ˜2.5 eV for LaFeAsO. The difference is similar in the effective models containing p orbitals of As, Se or Te (d p or d p p model), where U ranges from ˜4 eV for the 1111 family to ˜7 eV for the 11 family. The exchange interaction J has a similar tendency. The family dependence of models indicates a wide variation ranging from weak correlation regime (LaFePO) to substantially strong correlation regime (FeSe). The origin of the larger effective interaction in the 11 family is ascribed to smaller spread of the Wannier orbitals generating larger bare interaction, and to fewer screening channels by the other bands. This variation is primarily derived from the distance h between the pnictogen/chalcogen position and the Fe layer: The longer h for the 11 family generates more ionic character of the bonding between iron and anion atoms, while the shorter h for the 1111 family leads to more covalent-bonding character, the larger spread of the Wannier orbitals, and more efficient screening by the anion p orbitals. The screened interaction of the d model is strongly orbital

  15. Comparison of Fe XVIII and Fe XIX Line Emissions with Spectral Models

    NASA Astrophysics Data System (ADS)

    Desai, P.; Brickhouse, N. S.; Drake, J. J.; Edgar, R. J.; Hoogerwerf, R.; Kashyap, V.; Wargelin, B. J.; Smith, R. K.; Huenemoerder, D. P.; Liedahl, D. A.

    2005-06-01

    We discuss here the observations of Fe XVIII and XIX emission lines and compare the X-ray, EUV and FUV lines with the spectral codes widely used today (e.g. FAC and APEC). We assess the relative accuracy of these spectral models and try to identify the critical atomic data and processes. Capella with a narrow enhancement in its emission measure distribution at 6 MK provides a unique opportunity to test the Fe XVIII and Fe XIX model emissivities which peak from 6 to 8 MK. We use the summed spectra from Chandra HETG/ACIS-S and LETG/HRC-S, as well as contemporaneous EUVE and FUSE observations, to measure line ratios for comparison with predictions.

  16. Model study of CO inhibition of [NiFe]hydrogenase.

    PubMed

    Matsumoto, Takahiro; Kabe, Ryota; Nonaka, Kyoshiro; Ando, Tatsuya; Yoon, Ki-Seok; Nakai, Hidetaka; Ogo, Seiji

    2011-09-19

    We propose a modified mechanism for the inhibition of [NiFe]hydrogenase ([NiFe]H(2)ase) by CO. We present a model study, using a NiRu H(2)ase mimic, that demonstrates that (i) CO completely inhibits the catalytic cycle of the model compound, (ii) CO prefers to coordinate to the Ru(II) center rather than taking an axial position on the Ni(II) center, and (iii) CO is unable to displace a hydrido ligand from the NiRu center. We combine these studies with a reevaluation of previous studies to propose that, under normal circumstances, CO inhibits [NiFe]H(2)ase by complexing to the Fe(II) center. PMID:21853978

  17. Elastic and Piezoelectric Properties of Boron Nitride Nanotube Composites. Part II; Finite Element Model

    NASA Technical Reports Server (NTRS)

    Kim, H. Alicia; Hardie, Robert; Yamakov, Vesselin; Park, Cheol

    2015-01-01

    This paper is the second part of a two-part series where the first part presents a molecular dynamics model of a single Boron Nitride Nanotube (BNNT) and this paper scales up to multiple BNNTs in a polymer matrix. This paper presents finite element (FE) models to investigate the effective elastic and piezoelectric properties of (BNNT) nanocomposites. The nanocomposites studied in this paper are thin films of polymer matrix with aligned co-planar BNNTs. The FE modelling approach provides a computationally efficient way to gain an understanding of the material properties. We examine several FE models to identify the most suitable models and investigate the effective properties with respect to the BNNT volume fraction and the number of nanotube walls. The FE models are constructed to represent aligned and randomly distributed BNNTs in a matrix of resin using 2D and 3D hollow and 3D filled cylinders. The homogenisation approach is employed to determine the overall elastic and piezoelectric constants for a range of volume fractions. These models are compared with an analytical model based on Mori-Tanaka formulation suitable for finite length cylindrical inclusions. The model applies to primarily single-wall BNNTs but is also extended to multi-wall BNNTs, for which preliminary results will be presented. Results from the Part 1 of this series can help to establish a constitutive relationship for input into the finite element model to enable the modeling of multiple BNNTs in a polymer matrix.

  18. Isotropic hysteresis modeling of Fe-Co-B alloys

    NASA Astrophysics Data System (ADS)

    Hauser, Hans; Grössinger, Roland

    1999-04-01

    The energetic model of ferromagnetic hysteresis calculates the magnetic state of materials by minimizing the total energy function for statistical domain behavior. The physical constants of this model are derived from anisotropy energy constants, initial susceptibility, coercivity, and saturation magnetization. The approach shows a good agreement to the magnetization curves of FeCoB strips, also in dependence of applied stress.

  19. Toxicological Models Part B: Environmental Models

    NASA Astrophysics Data System (ADS)

    Garric, Jeanne; Thybaud, Eric

    Assessment of ecotoxicological risks due to chemical substances is based in part on establishing concentration-response relationships for different organisms, including plants, invertebrates, and vertebrates living on land, fresh water, or sea water. European regulations for assessing the risks due to chemical products thus recommend the measurement of toxic effects on at least three taxons (algae, crustacea, fish) [1]. The assessment becomes more relevant when based upon a variety of different organisms, with a range of different biological and ecological features (autotrophic or heterotrophic, benthic or pelagic habitat, and different modes of reproduction, growth, respiration, or feeding, etc.), but also when it describes the effects of contaminants on sensitive physiological functions such as growth and reproduction, which determine the balance of populations of terrestrial and aquatic species in their environment.

  20. Atomic Resolution Modeling of the Ferredoxin:[FeFe] Hydrogenase Complex from Chlamydomonas reinhardtii

    PubMed Central

    Chang, Christopher H.; King, Paul W.; Ghirardi, Maria L.; Kim, Kwiseon

    2007-01-01

    The [FeFe] hydrogenases HydA1 and HydA2 in the green alga Chlamydomonas reinhardtii catalyze the final reaction in a remarkable metabolic pathway allowing this photosynthetic organism to produce H2 from water in the chloroplast. A [2Fe-2S] ferredoxin is a critical branch point in electron flow from Photosystem I toward a variety of metabolic fates, including proton reduction by hydrogenases. To better understand the binding determinants involved in ferredoxin:hydrogenase interactions, we have modeled Chlamydomonas PetF1 and HydA2 based on amino-acid sequence homology, and produced two promising electron-transfer model complexes by computational docking. To characterize these models, quantitative free energy calculations at atomic resolution were carried out, and detailed analysis of the interprotein interactions undertaken. The protein complex model we propose for ferredoxin:HydA2 interaction is energetically favored over the alternative candidate by 20 kcal/mol. This proposed model of the electron-transfer complex between PetF1 and HydA2 permits a more detailed view of the molecular events leading up to H2 evolution, and suggests potential mutagenic strategies to modulate electron flow to HydA2. PMID:17660315

  1. Hexaferrites and phase relations in the iron-rich part of the system Sr-La-Co-Fe-O

    SciTech Connect

    Langhof, N.; Goebbels, M.

    2009-10-15

    The iron rich part of the system was examined in the temperature range of 1200-1380 deg. C in air, with focus on the solid solutions of M-type hexaferrites. Samples of suitable compositions were studied by electronprobe microanalysis (EPMA). Substituted Sr-hexaferrites in the system Sr-La-Co-Fe-O do not follow the 1:1 substitution mechanism of La/Co in M-type ferrites. Due to the presence and limited Co{sup 2+}-incorporation Fe{sup 3+}-ions are reduced to Fe{sup 2+} within the crystal lattice to obtain charge balance. In all examined M-type ferrites divalent iron is formed, even at 1200 deg. C. The substitution principle Sr{sup 2+}+Fe{sup 3+}reversibleLa{sup 3+}+(Fe{sup 2+}, Co{sup 2+}) yields to the general substitution formula for the M-type hexaferrite Sr{sup 2+}{sub 1-x}La{sup 3+}{sub x}Fe{sup 2+}{sub x-y}Co{sup 2+}{sub y}Fe{sup 3+}{sub 12-x}O{sup 19} (0<=x<=1 and 0<=y<=x). In addition Sr/La-perovskite{sub SS} ({sub SS}=solid solution), Co/Fe-spinel{sub SS}, hematite and magnetite are formed. Sr-hexaferrite exhibits at 1200 deg. C a limited solid solution with small amounts of Fe{sup 2+} (SrFe{sub 12}O{sub 19}reversibleSr{sub 0.3}La{sub 0.7}Co{sub 0.5}Fe{sup 2+}{sub 0.2}Fe{sub 11.3}O{sub 19}). At 1300 and 1380 deg. C a continuous solid solution series of the M-type hexaferrite is stable. SrFe{sub 12}O{sub 19} and LaCo{sub 0.4}Fe{sup 2+}{sub 0.6}Fe{sub 11}O{sub 19} are the end members at 1300 deg. C. The maximum Fe{sup 2+}O content is about 13 mol% in the M-type ferrite at 1380 deg. C (LaCo{sub 0.1}Fe{sup 2+}{sub 0.9}Fe{sub 11}O{sub 19}). - Graphical abstract: M-type hexaferrite solid solution series Sr{sub 1-x}La{sub x}Fe{sup 2+}{sub x-y}Co{sup 2+}{sub y}Fe{sup 3+}{sub 12-x}O{sup 19} (0<=x<=1 and 0<=y<=0.40) at 1300 deg. C; M-type contains significant amounts of FeO even at 1200 deg. C; blue=data from electronprobe microanalyses; SF{sub 6}=SrFe{sup 3+}{sub 12}O{sub 19}; LCoFf{sub 6}=LaCo{sub 0.4}Fe{sup 2+}{sub 0.6}Fe{sup 3+}{sub 11}O{sub 19}; S=SrO; L=La{sub 2

  2. Evaluation of the nucleation and coarsening kinetic behavior of the secondary hardening carbide of Fe-HCo-10Ni-1Mo-0.16C steel at two chromium levels, using an analytical and modeling approach: Part II

    NASA Astrophysics Data System (ADS)

    Oh, Y.; Machmeier, P. M.; Matuszewski, T.; Ayer, R.

    1997-06-01

    The effect of 1 % Cr addition on the resistivity during preaging and peak aging of an AF1410 based steel was examined by analytical and modeling approaches. The increased kinetics of aging resulting from a chromium addition, due to a variety of complex microstructural changes,was analyzed by Avrami-Mehl and Wert-Zener formulations, which were modified so that the exponent was a function of time. Using a eneralized Avrami equation, it was shown that the nucleation rate, N(t), at short aging times was large but became a rapidly declining function as N(t) approaches zero in a supersaturated system. A mathematical solution, using AF1410 steel carbide growth data at 510 °C, confirmed reported experimental evidence of second-stage carbide nucleation at 1 to 2 h.

  3. Spectral models for early time SN 2011fe observations

    NASA Astrophysics Data System (ADS)

    Baron, E.; Hoeflich, P.; Friesen, Brian; Sullivan, M.; Hsiao, E.; Ellis, R. S.; Gal-Yam, A.; Howell, D. A.; Nugent, P. E.; Dominguez, I.; Krisciunas, K.; Phillips, M. M.; Suntzeff, N.; Wang, L.; Thomas, R. C.

    2015-12-01

    We use observed UV through near-IR spectra to examine whether SN 2011fe can be understood in the framework of Branch-normal Type Ia supernovae (SNe Ia) and to examine its individual peculiarities. As a benchmark, we use a delayed-detonation model with a progenitor metallicity of Z⊙/20. We study the sensitivity of features to variations in progenitor metallicity, the outer density profile, and the distribution of radioactive nickel. The effect of metallicity variations in the progenitor have a relatively small effect on the synthetic spectra. We also find that the abundance stratification of SN 2011fe resembles closely that of a delayed-detonation model with a transition density that has been fit to other Branch-normal SNe Ia. At early times, the model photosphere is formed in material with velocities that are too high, indicating that the photosphere recedes too slowly or that SN 2011fe has a lower specific energy in the outer ≈0.1 M⊙ than does the model. We discuss several explanations for the discrepancies. Finally, we examine variations in both the spectral energy distribution and in the colours due to variations in the progenitor metallicity, which suggests that colours are only weak indicators for the progenitor metallicity, in the particular explosion model that we have studied. We do find that the flux in the U band is significantly higher at maximum light in the solar metallicity model than in the lower metallicity model and the lower metallicity model much better matches the observed spectrum.

  4. Redox response model for partly substituted cuprates

    SciTech Connect

    Oesterreicher, H. . Dept. of Chemistry)

    1994-05-01

    Inhomogeneous substitutions (e.g. clustering and preferential site occupations) in compounds such as YBa[sub 2](Cu[sub 1[minus]x]M[sub x])[sub 3]O[sub y] with M = Fe, Co, Ni, etc. are an unavoidable response to the changing redox environments in these O intercalation compounds. The authors collect here experimental evidence for various types of inhomogeneous distributions predicted on a thermodynamic model which considers the preferential desorption'' of O from various local environments. The parameter organizing the redox environment is [Delta]H* (incremental enthalpy of oxygen desorption per mol O[sub 2]). Theory suggests a sequence of discernible states represented by the acronym CLUSTER. With decreasing [Delta]H*, indications for several of these states are obtained from Moessbauer and other experiments. These states are characteristically shifted in [Delta]H* for different M. Also, further substitutions according to (YX)(BaZ)[sub 2](CuM)[sub 3]O[sub y] with X = Ca, Z = Sr, La can change the relevant [Delta]H* for these states, allowing prediction of their preparation conditions. Aspects of the complex electronic phase diagram as a function of redox preparation are discussed.

  5. A kinetic model for bacterial Fe(III) oxide reduction in batch cultures

    NASA Astrophysics Data System (ADS)

    Hacherl, Eric L.; Kosson, David S.; Cowan, Robert M.

    2003-04-01

    A model has been developed describing the microbial reduction of solid-phase electron acceptors (Fe(III) oxides) as well as dissolved electron acceptors (chelated Fe(III) or organic electron shuttles) in Shewanella alga BrY. The model utilized a multiple-substrate, Monod kinetics formulation. The Monod description of solid Fe(III) reduction requires a normalization of surface Fe concentration to biomass concentration in order to describe the "bioavailable" Fe(III) concentration. The model also contains provisions for irreversible sorption of Fe(II) to Fe(III) oxide surfaces and for the precipitation of Fe(III) carbonates. The loss of bioavailable Fe(III) due to sorption of Fe(II) was found to be minor, even for highly sorptive amorphous Fe(III) oxyhydroxides. However, the final extent of microbial reduction is very sensitive to the rate of siderite precipitation, assuming that siderite precipitation could partially occlude Fe(III) surface sites. The use of a multisubstrate Monod kinetics model enabled an evaluation of the effects of electron shuttles on solid Fe(III) reduction. Because the electron shuttle is recycled, very small additions can greatly increase the overall rate of solid Fe(III) reduction.

  6. Reaction-based reactive transport modeling of Fe(III)

    SciTech Connect

    Kemner, K.M.; Kelly, S.D.; Burgos, Bill; Roden, Eric

    2006-06-01

    This research project (started Fall 2004) was funded by a grant to Argonne National Laboratory, The Pennsylvania State University, and The University of Alabama in the Integrative Studies Element of the NABIR Program (DE-FG04-ER63914/63915/63196). Dr. Eric Roden, formerly at The University of Alabama, is now at the University of Wisconsin, Madison. Our project focuses on the development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. This work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and is directly aligned with the Scheibe et al. NABIR FRC Field Project at Area 2.

  7. Moessbauer spectroscopic investigations of bimetallic FeCo, FeNi, and FeRu model catalysts supported on magnesium hydroxide carbonate

    SciTech Connect

    Nagorny, K.; Bubert, S.

    1987-11-01

    FeCo, FeNi, and FeRu alloys supported on basic magnesium carbonate have been prepared by precipitation from salt solutions at 340 K onto the support using ion exchange and have been subsequently annealed for 20 h under argon. The reduction, oxidation, and sintering behavior of the samples under H/sub 2/ or CO exposure has been investigated at 723 K by means of Moessbauer spectroscopy. The comparison of the resonance absorption areas of the spectra taken at 4 and 295 K allowed the calculation of the Debye temperatures and Debye-Waller factors of the different components. From the Debye-Waller factors the relative fractions could be extrapolated to the conditions at 0 K. The kinetics of the H/sub 2/ exposure showed an increase in the reduction velocity as well as in the degree of reduction in the sequence FeCo < FeNi < FeRu. Above a critical particle diameter a phase separation occurred because of the segregation of an iron-rich phase at the surface of the alloy particles. The kinetics of the CO exposure demonstrated that with FeCo clusters iron(III) surface oxide layers form, whereas with FeNi clusters iron(II) surface oxide layers are generated. FeCo clusters with a cobalt content of 25% form only unstable surface carbides, whereas clusters with a cobalt content of about 5% form stable bulk carbides. The velocity of carbide formation increases with decreasing particle size. Based on the present data a model is proposed which explains the behavior of FeMe/magnesium hydroxide carbonates catalysts in H/sub 2/ and CO atmospheres.

  8. 12 CFR Appendix A to Part 573 - Model Privacy Form

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... the model form under this part, must comply with section 624 of the FCRA and 12 CFR part 571, subpart... 12 Banks and Banking 6 2013-01-01 2012-01-01 true Model Privacy Form A Appendix A to Part 573... INFORMATION Pt. 573, App. A Appendix A to Part 573—Model Privacy Form A. The Model Privacy Form...

  9. 12 CFR Appendix A to Part 573 - Model Privacy Form

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... the model form under this part, must comply with section 624 of the FCRA and 12 CFR part 571, subpart... 12 Banks and Banking 5 2011-01-01 2011-01-01 false Model Privacy Form A Appendix A to Part 573... INFORMATION Pt. 573, App. A Appendix A to Part 573—Model Privacy Form A. The Model Privacy Form...

  10. 12 CFR Appendix A to Part 573 - Model Privacy Form

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... the model form under this part, must comply with section 624 of the FCRA and 12 CFR part 571, subpart... 12 Banks and Banking 6 2012-01-01 2012-01-01 false Model Privacy Form A Appendix A to Part 573... INFORMATION Pt. 573, App. A Appendix A to Part 573—Model Privacy Form A. The Model Privacy Form...

  11. 12 CFR Appendix A to Part 573 - Model Privacy Form

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... the model form under this part, must comply with section 624 of the FCRA and 12 CFR part 571, subpart... 12 Banks and Banking 6 2014-01-01 2012-01-01 true Model Privacy Form A Appendix A to Part 573... INFORMATION Pt. 573, App. A Appendix A to Part 573—Model Privacy Form A. The Model Privacy Form...

  12. 12 CFR Appendix A to Part 573 - Model Privacy Form

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... the model form under this part, must comply with section 624 of the FCRA and 12 CFR part 571, subpart... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Model Privacy Form A Appendix A to Part 573... INFORMATION Pt. 573, App. A Appendix A to Part 573—Model Privacy Form A. The Model Privacy Form...

  13. The Model [NiFe]-Hydrogenases of Escherichia coli.

    PubMed

    Sargent, F

    2016-01-01

    In Escherichia coli, hydrogen metabolism plays a prominent role in anaerobic physiology. The genome contains the capability to produce and assemble up to four [NiFe]-hydrogenases, each of which are known, or predicted, to contribute to different aspects of cellular metabolism. In recent years, there have been major advances in the understanding of the structure, function, and roles of the E. coli [NiFe]-hydrogenases. The membrane-bound, periplasmically oriented, respiratory Hyd-1 isoenzyme has become one of the most important paradigm systems for understanding an important class of oxygen-tolerant enzymes, as well as providing key information on the mechanism of hydrogen activation per se. The membrane-bound, periplasmically oriented, Hyd-2 isoenzyme has emerged as an unusual, bidirectional redox valve able to link hydrogen oxidation to quinone reduction during anaerobic respiration, or to allow disposal of excess reducing equivalents as hydrogen gas. The membrane-bound, cytoplasmically oriented, Hyd-3 isoenzyme is part of the formate hydrogenlyase complex, which acts to detoxify excess formic acid under anaerobic fermentative conditions and is geared towards hydrogen production under those conditions. Sequence identity between some Hyd-3 subunits and those of the respiratory NADH dehydrogenases has led to hypotheses that the activity of this isoenzyme may be tightly coupled to the formation of transmembrane ion gradients. Finally, the E. coli genome encodes a homologue of Hyd-3, termed Hyd-4, however strong evidence for a physiological role for E. coli Hyd-4 remains elusive. In this review, the versatile hydrogen metabolism of E. coli will be discussed and the roles and potential applications of the spectrum of different types of [NiFe]-hydrogenases available will be explored. PMID:27134027

  14. Landau-Heisenberg Hamiltonian model for FeRh

    NASA Astrophysics Data System (ADS)

    Derlet, P. M.

    2012-05-01

    An empirical model is developed for the FeRh system with the view of gaining further insight into the first-order antiferromagnetic-ferromagnetic (AFM-FM) and volume phase transition known to occur at 370 K. A volume-per-atom dependent minimal nearest neighbor Landau-Heisenberg Hamiltonian is employed in which longitudinal and transverse moment fluctuations are considered for both the Fe and Rh atoms. As a function of volume-per-atom, the corresponding onsite Landau function coefficients and the nearest-neighbor exchange parameters are fitted directly to a wide range of existing colinear and noncolinear density functional theory calculations. Using a developed Monte Carlo strategy the thermal properties of the AFM and FM phases are investigated, as well as the phase transition. It is found that the model is able to describe well the thermal expansion, heat capacities and the associated entropy increase that accompanies the magnetic/volume phase transition. The model suggests an equally important role for the magnetic and volume fluctuations in driving the phase transition.

  15. Modeling the sublattice magnetizations for the layered bcc nanojunction … Fe[Fe1-cCoc ] ℓ Fe … systems

    NASA Astrophysics Data System (ADS)

    Ashokan, V.; Abou Ghantous, M.; Khater, A.

    2015-12-01

    Ferromagnetic nanojunctions … Fe[Fe1-cCoc ] ℓ Fe …, with ℓ is the number of layers which constitute the nanojunction, based on Fe/Co alloy are considered for the first time in this work. We model the salient magnetic properties of the layered ferromagnetic nanostructures between magnetically ordered iron leads. The effective field theory (EFT) Ising spin method is used to compute reliable Jav exchange values for the VCA Fe/Co alloy materials in comparison with experimental data and compared to existing DFT calculated exchange interactions. The new set of exchange interaction values between pairs of nearest neighbors atom in the alloy are deduced and agree with previous known measurement of lattice constant for this alloy. Using the combined EFT and mean field theory (MFT) spin methods, the sublattice magnetizations of the Fe and Co sites on the individual bcc basal planes of the layered nanostructures, are calculated and analyzed. The sublattice magnetizations, effective magnetic moments per site, and the possible ferromagnetic order of the layers [Fe1-cCoc ] ℓ on the individual bcc atomic planes of the embedded nanostructures for all temperatures and in particular for TcFe ≤ T ≤Tα→γ are presented as a function of temperature and thicknesses of the layered ferromagnetic nanostructures, for different stable concentrations c=0.25, 0.5 and 0.75. In the absence of first principles calculations for these basic physical variables for the layered nanostructures between iron leads, the combined EFT and MFT approach yields the only available information for them at present in the absence of a possible Curie temperature for these alloys. These variables are necessary for certain spin dynamic computations, as for the ballistic magnon transport across embedded nanojunctions in magnonics. The model is general, and may applied directly to other composite magnetic elements and embedded nanostructures.

  16. Five forest harvesting simulation models, part 1: modeling characteristics

    SciTech Connect

    Goulet, D.V.; Iff, R.H.; Sirois, D.L.

    1980-01-01

    This paper is the first of two describing the conclusions from a study to determine the state of the art in timber harvesting computer simulation modeling. Five models were evaluated -- Forest Harvesting Simulation Model (FHSM), Full Tree Field Chipping (FTFC), Harvesting System Simulator (HSS), Simulation Applied to Logging Systems (SAPLOS), and Timber Harvesting and Transport Simulator (THATS) -- for their potential use in southern forest harvesting operations. In Part I, modeling characteristics and overall model philosophy are identified and illustrated. This includes a detailed discussion of the wood flow process in each model, accounting strategies for productive/non-productive times, performance variables, and the different types of harvesting systems modelable. In Part II we discuss user implementation problems. Those dealt with in detail are: What questions can be asked of the model. What are the modeling tradeoffs, and how do they impact on the analysis. What are the computer skills necessary to effectively work with the model. What computer support is needed. Are the models operational. The results provide a good picture of the state of the art in timber harvesting computer simulation. Much learning has occurred in the generation of these models, and many modeling and implementation problems have been uncovered, some of which remain unsolved. Hence, the user needs to examine closely the model and the intended application so that results will represent usable, valid data. It is recommended that the development of timber harvesting computer simulation modeling continue, so that existing and proposed timber harvesting strategies can be adequately evaluated. A set of design criteria are proposed. (Refs. 21).

  17. 12 CFR Appendix A to Part 716 - Model Privacy Form

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... the model form under this part, must comply with section 624 of the FCRA and 12 CFR part 717, subpart... 12 Banks and Banking 7 2012-01-01 2012-01-01 false Model Privacy Form A Appendix A to Part 716... CONSUMER FINANCIAL INFORMATION Pt. 716, App. A Appendix A to Part 716—Model Privacy Form A.The...

  18. 12 CFR Appendix A to Part 716 - Model Privacy Form

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... the model form under this part, must comply with section 624 of the FCRA and 12 CFR part 717, subpart... 12 Banks and Banking 7 2013-01-01 2013-01-01 false Model Privacy Form A Appendix A to Part 716... CONSUMER FINANCIAL INFORMATION Pt. 716, App. A Appendix A to Part 716—Model Privacy Form A.The...

  19. 12 CFR Appendix A to Part 716 - Model Privacy Form

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... the model form under this part, must comply with section 624 of the FCRA and 12 CFR part 717, subpart... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Model Privacy Form A Appendix A to Part 716... CONSUMER FINANCIAL INFORMATION Pt. 716, App. A Appendix A to Part 716—Model Privacy Form A.The...

  20. 12 CFR Appendix A to Part 716 - Model Privacy Form

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... the model form under this part, must comply with section 624 of the FCRA and 12 CFR part 717, subpart... 12 Banks and Banking 6 2011-01-01 2011-01-01 false Model Privacy Form A Appendix A to Part 716... CONSUMER FINANCIAL INFORMATION Pt. 716, App. A Appendix A to Part 716—Model Privacy Form A.The...

  1. JPEG-2000 Part 10 Verification Model

    Energy Science and Technology Software Center (ESTSC)

    2003-03-04

    VM10 is a research software implementation of the ISO/IEC JPEG-2000 Still Image Coding standard (ISO international Standard 15444). JPEG-2000 image coding involves subband codiing and compression of digital raster images to facilitate storage and transmission of such imagery. Images are decomposed into space/scale subbands using cascades of two-dimensional (tensor product) discrete wavelet transforms. The wavelet transforms can be either reversible (integer-to-integer) transforms or irreversible (integer-to-float). The subbands in each resolution level are quantized by uniformmore » scalar quantization in the irreversible case. The resulting integer subbands in each resolution level are partitioned into spatially localized code blocks to facilitate localized entropy decoding. Code blocks are encoded and packaged into an embedded bitstream using binary arithmetic bitplane coding (the MQ Coder algorithm applied to hierarchical bitplane coding (the MQ coder algorithm applied to hierachical bitplane context modeling). The resultant compressed bitstream is configured for use with the JPIP interactive client-server protocol (JPEG-2000 part 9). VM10 is written in ANSI C++ using the Biltz++ array class library. To enable development of multidimensional image coding algorithms, VM10 is templated on the dimension of the array containers. It was developed with the GNU g++ compiler on both Linux (Red Hat) and Windows/cygwin platforms, although it should compile and run under other ANSI C++ compilers as well. Software design is highly modular and object-oriented in order to facilitate rapid development and frequent revision and experimentation. No attempt has been made to optimize the run-time performance of the code. The software performs both the encoding and decoding operations involved in JPEG-2000 image coding, as implemented in apps/compress/main.cpp and apps/expand/main.cpp. VM10 implements all of the JPEG-2000 baseline (Part 1, ISO 15444-1) and portions of the

  2. JPEG-2000 Part 10 Verification Model

    SciTech Connect

    Mniszewski, Susan; Rivenburgh, Reid; Brislawn, Chris

    2003-03-04

    VM10 is a research software implementation of the ISO/IEC JPEG-2000 Still Image Coding standard (ISO international Standard 15444). JPEG-2000 image coding involves subband codiing and compression of digital raster images to facilitate storage and transmission of such imagery. Images are decomposed into space/scale subbands using cascades of two-dimensional (tensor product) discrete wavelet transforms. The wavelet transforms can be either reversible (integer-to-integer) transforms or irreversible (integer-to-float). The subbands in each resolution level are quantized by uniform scalar quantization in the irreversible case. The resulting integer subbands in each resolution level are partitioned into spatially localized code blocks to facilitate localized entropy decoding. Code blocks are encoded and packaged into an embedded bitstream using binary arithmetic bitplane coding (the MQ Coder algorithm applied to hierarchical bitplane coding (the MQ coder algorithm applied to hierachical bitplane context modeling). The resultant compressed bitstream is configured for use with the JPIP interactive client-server protocol (JPEG-2000 part 9). VM10 is written in ANSI C++ using the Biltz++ array class library. To enable development of multidimensional image coding algorithms, VM10 is templated on the dimension of the array containers. It was developed with the GNU g++ compiler on both Linux (Red Hat) and Windows/cygwin platforms, although it should compile and run under other ANSI C++ compilers as well. Software design is highly modular and object-oriented in order to facilitate rapid development and frequent revision and experimentation. No attempt has been made to optimize the run-time performance of the code. The software performs both the encoding and decoding operations involved in JPEG-2000 image coding, as implemented in apps/compress/main.cpp and apps/expand/main.cpp. VM10 implements all of the JPEG-2000 baseline (Part 1, ISO 15444-1) and portions of the published

  3. Photocatalytic hydrogen production from a simple water-soluble [FeFe]-hydrogenase model system.

    PubMed

    Cao, Wei-Ning; Wang, Feng; Wang, Hong-Yan; Chen, Bin; Feng, Ke; Tung, Chen-Ho; Wu, Li-Zhu

    2012-08-21

    Combined with a simple water soluble [FeFe]-hydrogenase mimic 1, Ru(bpy)(3)(2+) and ascorbic acid enable hydrogen production photocatalytically. More than 88 equivalents of H(2) were achieved in water, which is much better than that obtained in an organic solvent or a mixture of organic solvent and water. PMID:22772838

  4. Refined model of the {Fe9} magnetic molecule from low-temperature inelastic neutron scattering studies

    SciTech Connect

    Engelhardt, Larry; Demmel, Franz; Luban, Marshall; Timco, Grigore A; Tuna, Floriana; Winpenny, Richard E

    2014-06-01

    We present a refined model of the {Fe9} tridiminished icosahedron magnetic molecule system. This molecule was originally modeled as being composed of two ({Fe3} and {Fe6}) clusters, with the Fe3+ ions within each cluster being coupled via exchange interactions, but with no coupling between the clusters. The present inelastic neutron scattering (INS) measurements were used to probe the low-lying energy spectrum of {Fe9}, and these results demonstrate that the previously published model of two uncoupled clusters is incomplete. To achieve agreement between the experiment and theory, we have augmented the model with relatively small exchange coupling between the clusters. A combination of Lanczos matrix diagonalization and quantum Monte Carlo simulations have been used to achieve good agreement between the experimental data and the improved model of the full {Fe9} system despite the complexity of this model (with Hilbert space dimension >107).

  5. Hydrogen Production Catalyzed by Bidirectional, Biomimetic Models of the [FeFe]-Hydrogenase Active Site.

    PubMed

    Lansing, James C; Camara, James M; Gray, Danielle E; Rauchfuss, Thomas B

    2014-10-27

    Active site mimics of [FeFe]-hydrogenase are shown to be bidirectional catalysts, producing H2 upon treatment with protons and reducing equivalents. This reactivity complements the previously reported oxidation of H2 by these same catalysts in the presence of oxidants. The complex Fe2(adt(Bn))(CO)3(dppv)(PFc*(Et2) ) ([1](0); adt(Bn) = (SCH2)2NBn, dppv = cis-1,2-bis(diphenylphosphino)ethylene, PFc*(Et2) = Et2PCH2C5Me4FeCp*) reacts with excess [H(OEt2)2]BAr(F) 4 (BAr(F) 4 (-) = B(C6H3-3,5-(CF3)2)4 (-)) to give ∼0.5 equiv of H2 and [Fe2(adt(Bn)H)(CO)3(dppv)(PFc*(Et2) )](2+) ([1H](2+)). The species [1H](2+) consists of a ferrocenium ligand, an N-protonated amine, and an Fe(I)Fe(I) core. In the presence of additional reducing equivalents in the form of decamethylferrocene (Fc*), hydrogen evolution is catalytic, albeit slow. The related catalyst Fe2(adt(Bn))(CO)3(dppv)(PMe3) (3) behaves similarly in the presence of Fc*, except that in the absence of excess reducing agent it converts to the catalytically inactive μ-hydride derivative [μ-H3](+). Replacement of the adt in [1](0) with propanedithiolate (pdt) results in a catalytically inactive complex. In the course of synthesizing [FeFe]-hydrogenase mimics, new routes to ferrocenylphosphine ligands and nonamethylferrocene were developed. PMID:25364093

  6. Aluminum Deoxidation Equilibria in Liquid Iron: Part II. Thermodynamic Modeling

    NASA Astrophysics Data System (ADS)

    Paek, Min-Kyu; Pak, Jong-Jin; Kang, Youn-Bae

    2015-10-01

    Al deoxidation equilibria in liquid iron over the whole composition range from very low Al ([pct Al] = 0.0027) to almost pure liquid Al were thermodynamically modeled for the first time using the Modified Quasichemical Model in the pair approximation for the liquid phase. The present modeling is distinguished from previous approaches in many ways. First, very strong attractions between metallic components, Fe and Al, and non-metallic component, O, were taken into account explicitly in terms of Short-Range Ordering. Second, the present thermodynamic modeling does not distinguish solvent and solutes among metallic components, and the model calculation can be applied from pure liquid Fe to pure liquid Al. Therefore, this approach is thermodynamically self-consistent, contrary to the previous approaches using interaction parameter formalism. Third, the present thermodynamic modeling describes an integral Gibbs energy of the liquid alloy in the framework of CALPHAD; therefore, it can be further used to develop a multicomponent thermodynamic database for liquid steel. Fourth, only a small temperature-independent parameter for ternary liquid was enough to account for the Al deoxidation over wide concentration (0.0027 < [pct Al] < 100) and wide temperature range [1823 K to 2139 K (1550 °C to 1866 °C)]. Gibbs energies of Fe-O and Al-O binary liquid solutions at metal-rich region (up to oxide saturation) were modeled, and relevant model parameters were optimized. By merging these Gibbs energy descriptions with that of Fe-Al binary liquid modeled by the same modeling approach, the Gibbs energy of ternary Fe-Al-O solution at metal-rich region was obtained along with one small ternary parameter. It was shown that the present model successfully reproduced all available experimental data for the Al deoxidation equilibria. Limit of previously used interaction parameter formalism at high Al concentration is discussed.

  7. A biochemical/biophysical 3D FE intervertebral disc model.

    PubMed

    Schroeder, Y; Huyghe, J M; van Donkelaar, C C; Ito, K

    2010-10-01

    Present research focuses on different strategies to preserve the degenerated disc. To assure long-term success of novel approaches, favorable mechanical conditions in the disc tissue are essential. To evaluate these, a model is required that can determine internal mechanical conditions which cannot be directly measured as a function of assessable biophysical characteristics. Therefore, the objective is to evaluate if constitutive and material laws acquired on isolated samples of nucleus and annulus tissue can be used directly in a whole-organ 3D FE model to describe intervertebral disc behavior. The 3D osmo-poro-visco-hyper-elastic disc (OVED) model describes disc behavior as a function of annulus and nucleus tissue biochemical composition, organization and specific constituent properties. The description of the 3D collagen network was enhanced to account for smaller fibril structures. Tissue mechanical behavior tests on isolated nucleus and annulus samples were simulated with models incorporating tissue composition to calculate the constituent parameter values. The obtained constitutive laws were incorporated into the whole-organ model. The overall behavior and disc properties of the model were corroborated against in vitro creep experiments of human L4/L5 discs. The OVED model simulated isolated tissue experiments on confined compression and uniaxial tensile test and whole-organ disc behavior. This was possible, provided that secondary fiber structures were accounted for. The fair agreement (radial bulge, axial creep deformation and intradiscal pressure) between model and experiment was obtained using constitutive properties that are the same for annulus and nucleus. Both tissue models differed in the 3D OVED model only by composition. The composition-based modeling presents the advantage of reducing the numbers of material parameters to a minimum and to use tissue composition directly as input. Hence, this approach provides the possibility to describe internal

  8. Assessment of Experimental Data and Thermodynamic Modeling in the Zr-Fe-O System

    NASA Astrophysics Data System (ADS)

    Fabrichnaya, Olga; Pavlyuchkov, Dmytro

    2016-01-01

    The thermodynamic parameters of the ZrO2-FeO-Fe2O3 system were assessed based on experimental data for the ZrO-FeO and ZrO2-Fe3O4 systems for the first time. The solubility of FeO and Fe2O3 in the ZrO2-based solid solutions and the solubility of ZrO2 in the Fe2O3 and Fe3O4 phases were taken into account and described by compound energy formalism. A partially ionic liquid model was used to describe the liquid phase. The isothermal section and liquidus surface of the ZrO2-FeO-Fe2O3 system were calculated. Data on binary systems were combined with the description of the ZrO2-FeO-Fe2O3 system. Phase diagrams were calculated using a thermodynamic description based on advanced models. An equilibrium between the metallic liquid and solid ZrO2 was calculated and compared with experimental data. Substantial differences between the calculations and the results of experiments were found, as in the calculations of previous research.

  9. Hydrogen Production Catalyzed by Bidirectional, Biomimetic Models of the [FeFe]-Hydrogenase Active Site

    PubMed Central

    2015-01-01

    Active site mimics of [FeFe]-hydrogenase are shown to be bidirectional catalysts, producing H2 upon treatment with protons and reducing equivalents. This reactivity complements the previously reported oxidation of H2 by these same catalysts in the presence of oxidants. The complex Fe2(adtBn)(CO)3(dppv)(PFc*Et2) ([1]0; adtBn = (SCH2)2NBn, dppv = cis-1,2-bis(diphenylphosphino)ethylene, PFc*Et2 = Et2PCH2C5Me4FeCp*) reacts with excess [H(OEt2)2]BArF4 (BArF4– = B(C6H3-3,5-(CF3)2)4–) to give ∼0.5 equiv of H2 and [Fe2(adtBnH)(CO)3(dppv)(PFc*Et2)]2+ ([1H]2+). The species [1H]2+ consists of a ferrocenium ligand, an N-protonated amine, and an FeIFeI core. In the presence of additional reducing equivalents in the form of decamethylferrocene (Fc*), hydrogen evolution is catalytic, albeit slow. The related catalyst Fe2(adtBn)(CO)3(dppv)(PMe3) (3) behaves similarly in the presence of Fc*, except that in the absence of excess reducing agent it converts to the catalytically inactive μ-hydride derivative [μ-H3]+. Replacement of the adt in [1]0 with propanedithiolate (pdt) results in a catalytically inactive complex. In the course of synthesizing [FeFe]-hydrogenase mimics, new routes to ferrocenylphosphine ligands and nonamethylferrocene were developed. PMID:25364093

  10. Charge Exchange-induced X-Ray Emission of Fe xxv and Fe xxvI via a Streamlined Model

    NASA Astrophysics Data System (ADS)

    Mullen, P. D.; Cumbee, R. S.; Lyons, D.; Stancil, P. C.

    2016-06-01

    Charge exchange (CX) is an important process for the modeling of X-ray spectra obtained by the Chandra, XMM-Newton, and Suzaku X-ray observatories, as well as the anticipated Astro-H mission. The understanding of the observed X-ray spectra produced by many astrophysical environments is hindered by the current incompleteness of available atomic and molecular data—especially for CX. Here, we implement a streamlined program set that applies quantum defect methods and the Landau–Zener theory to generate total, n-resolved, and n{\\ell }S-resolved cross sections for any given projectile ion/target CX collision. By using these data in a cascade model for X-ray emission, theoretical spectra for such systems can be predicted. With these techniques, Fe25+ and Fe26+ CX collisions with H, He, H2, N2, H2O, and CO are studied for single-electron capture (SEC). These systems have been selected because they illustrate computational difficulties for high projectile charges. Furthermore, Fe xxv and Fe xxvi emission lines have been detected in the Galactic center and Galactic ridge. Theoretical X-ray spectra for these collision systems are compared to experimental data generated by an electron-beam ion trap study. Several ℓ-distribution models have been tested for Fe25+ and Fe26+ SEC. Such analyses suggests that commonly used ℓ-distribution models struggle to accurately reflect the true distribution of electron capture as understood by more advanced theoretical methods.

  11. 31 CFR Appendix A to Part 132 - Model Notice

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... one another can be found at part 233 of title 12 of the U.S. Code of Federal Regulations (12 CFR part 233) and part 132 of title 31 of the U.S. Code of Federal Regulations (31 CFR part 132). ... INTERNET GAMBLING Pt. 132, App. A Appendix A to Part 132—Model Notice Re: U.S. Unlawful Internet...

  12. 12 CFR Appendix A to Part 233 - Model Notice

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Federal Regulations (12 CFR part 233) and part 132 of title 31 of the U.S. Code of Federal Regulations (31 CFR part 132). ... FUNDING OF UNLAWFUL INTERNET GAMBLING (REGULATION GG) Part 233, App. A Appendix A to Part 233—Model...

  13. 12 CFR Appendix A to Part 233 - Model Notice

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Federal Regulations (12 CFR part 233) and part 132 of title 31 of the U.S. Code of Federal Regulations (31 CFR part 132). ... FUNDING OF UNLAWFUL INTERNET GAMBLING (REGULATION GG) Part 233, App. A Appendix A to Part 233—Model...

  14. Modeling and FE Simulation of Quenchable High Strength Steels Sheet Metal Hot Forming Process

    NASA Astrophysics Data System (ADS)

    Liu, Hongsheng; Bao, Jun; Xing, Zhongwen; Zhang, Dejin; Song, Baoyu; Lei, Chengxi

    2011-08-01

    High strength steel (HSS) sheet metal hot forming process is investigated by means of numerical simulations. With regard to a reliable numerical process design, the knowledge of the thermal and thermo-mechanical properties is essential. In this article, tensile tests are performed to examine the flow stress of the material HSS 22MnB5 at different strains, strain rates, and temperatures. Constitutive model based on phenomenological approach is developed to describe the thermo-mechanical properties of the material 22MnB5 by fitting the experimental data. A 2D coupled thermo-mechanical finite element (FE) model is developed to simulate the HSS sheet metal hot forming process for U-channel part. The ABAQUS/explicit model is used conduct the hot forming stage simulations, and ABAQUS/implicit model is used for accurately predicting the springback which happens at the end of hot forming stage. Material modeling and FE numerical simulations are carried out to investigate the effect of the processing parameters on the hot forming process. The processing parameters have significant influence on the microstructure of U-channel part. The springback after hot forming stage is the main factor impairing the shape precision of hot-formed part. The mechanism of springback is advanced and verified through numerical simulations and tensile loading-unloading tests. Creep strain is found in the tensile loading-unloading test under isothermal condition and has a distinct effect on springback. According to the numerical and experimental results, it can be concluded that springback is mainly caused by different cooling rats and the nonhomogengeous shrink of material during hot forming process, the creep strain is the main factor influencing the amount of the springback.

  15. ATOMIC DATA AND SPECTRAL MODEL FOR Fe III

    SciTech Connect

    Bautista, Manuel A.; Ballance, Connor P.; Quinet, Pascal

    2010-08-01

    We present new atomic data (radiative transitions rates and collision strengths) from large-scale calculations and a non-LTE spectral model for Fe III. This model is in very good agreement with observed astronomical emission spectra, in contrast with previous models that yield large discrepancies in observations. The present atomic computations employ a combination of atomic physics methods, e.g., relativistic Hartree-Fock, the Thomas-Fermi-Dirac potential, and Dirac-Fock computation of A-values and the R-matrix with intermediate coupling frame transformation and the Dirac R-matrix. We study advantages and shortcomings of each method. It is found that the Dirac R-matrix collision strengths yield excellent agreement with observations, much improved over previously available models. By contrast, the transformation of the LS-coupling R-matrix fails to yield accurate effective collision strengths at around 10{sup 4} K, despite using very large configuration expansions, due to the limited treatment of spin-orbit effects in the near-threshold resonances of the collision strengths. The present work demonstrates that accurate atomic data for low-ionization iron-peak species are now within reach.

  16. 12 CFR Appendix A to Part 704 - Model Forms

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 6 2011-01-01 2011-01-01 false Model Forms A Appendix A to Part 704 Banks and... Pt. 704, App. A Appendix A to Part 704—Model Forms This appendix contains sample forms intended for... Prioritization and Model Forms Part I—Optional Capital Prioritization Notwithstanding any other provision in...

  17. Positron annihilation study of Fe-ion irradiated reactor pressure vessel model alloys

    NASA Astrophysics Data System (ADS)

    Chen, L.; Li, Z. C.; Schut, H.; Sekimura, N.

    2016-01-01

    The degradation of reactor pressure vessel steels under irradiation, which results from the hardening and embrittlement caused by a high number density of nanometer scale damage, is of increasingly crucial concern for safe nuclear power plant operation and possible reactor lifetime prolongation. In this paper, the radiation damage in model alloys with increasing chemical complexity (Fe, Fe-Cu, Fe-Cu-Si, Fe-Cu-Ni and Fe-Cu-Ni-Mn) has been studied by Positron Annihilation Doppler Broadening spectroscopy after 1.5 MeV Fe-ion implantation at room temperature or high temperature (290 oC). It is found that the room temperature irradiation generally leads to the formation of vacancy-type defects in the Fe matrix. The high temperature irradiation exhibits an additional annealing effect for the radiation damage. Besides the Cu-rich clusters observed by the positron probe, the results show formation of vacancy-Mn complexes for implantation at low temperatures.

  18. A [NiFe]hydrogenase model that catalyses the release of hydrogen from formic acid.

    PubMed

    Nguyen, Nga T; Mori, Yuki; Matsumoto, Takahiro; Yatabe, Takeshi; Kabe, Ryota; Nakai, Hidetaka; Yoon, Ki-Seok; Ogo, Seiji

    2014-11-11

    We report the decomposition of formic acid to hydrogen and carbon dioxide, catalysed by a NiRu complex originally developed as a [NiFe]hydrogenase model. This is the first example of H2 evolution, catalysed by a [NiFe]hydrogenase model, which does not require additional energy. PMID:25234420

  19. Exchange-bias phenomena and modeling in nanocrystalline powders of MnO/FeCo and NiO/Fe

    NASA Astrophysics Data System (ADS)

    Cornejo, D. R.; Padrón Hernández, E.; Azevedo, A.; Rezende, S. M.

    2005-05-01

    An approach towards the modeling of the magnetic behavior in heterogeneous systems of exchange-coupled antiferromagnetic (AF) and ferromagnetic (FM) particles with composition (AF)x+(FM)1-x is presented. The model is based on the Preisach hysteresis model and correctly predicts the correlation between the exchange-bias field and the mean grain size of the material, as established from the measurements of the hysteresis loops in mechanically alloyed (MnO)+(α-FeCo). The model was also used to calculate the unidirectional anisotropy interface energies in both this and (NiO)x+(α-Fe)1-x system; in the latter case, the predicted value was in full agreement with that reported for antiferromagnetic layers of NiO.

  20. Modeling of surface myoelectric signals--Part I: Model implementation.

    PubMed

    Merletti, R; Lo Conte, L; Avignone, E; Guglielminotti, P

    1999-07-01

    The relationships between the parameters of active motor units (MU's) and the features of surface electromyography (EMG) signals have been investigated using a mathematical model that represents the surface EMG as a summation of contributions from the single muscle fibers. Each MU has parallel fibers uniformly scattered within a cylindrical volume of specified radius embedded in an anisotropic medium. Two action potentials, each modeled as a current tripole, are generated at the neuromuscular junction, propagate in opposite directions and extinguish at the fiber-tendon endings. The neuromuscular junctions and fiber-tendon endings are uniformly scattered within regions of specified width. Muscle fiber conduction velocity and average fiber length to the right and left of the center of the innervation zone are also specified. The signal produced by MU's with different geometries and conduction velocities are superimposed. Monopolar, single differential and double differential signals are computed from electrodes placed in equally spaced locations on the surface of the muscle and are displayed as functions of any of the model's parameters. Spectral and amplitude variables and conduction velocity are estimated from the surface signals and displayed as functions of any of the model's parameters. The influence of fiber-end effects, electrode misalignment, tissue anisotropy, MU's location and geometry are discussed. Part II of this paper will focus on the simulation and interpretation of experimental signals. PMID:10396899

  1. 12 CFR Appendix B to Part 202 - Model Application Forms

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 2 2013-01-01 2013-01-01 false Model Application Forms B Appendix B to Part... CREDIT OPPORTUNITY ACT (REGULATION B) Pt. 202, App. B Appendix B to Part 202—Model Application Forms 1. This appendix contains five model credit application forms, each designated for use in a...

  2. 12 CFR Appendix A to Part 213 - Model Forms

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 2 2011-01-01 2011-01-01 false Model Forms A Appendix A to Part 213 Banks and Banking FEDERAL RESERVE SYSTEM BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM CONSUMER LEASING (REGULATION M) Pt. 213, App. A Appendix A to Part 213—Model Forms A-1Model Open-End or Finance Vehicle...

  3. 12 CFR Appendix B to Part 1002 - Model Application Forms

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 8 2013-01-01 2013-01-01 false Model Application Forms B Appendix B to Part... B) Pt. 1002, App. B Appendix B to Part 1002—Model Application Forms 1. This appendix contains five model credit application forms, each designated for use in a particular type of consumer...

  4. 12 CFR Appendix B to Part 202 - Model Application Forms

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 2 2014-01-01 2014-01-01 false Model Application Forms B Appendix B to Part... CREDIT OPPORTUNITY ACT (REGULATION B) Pt. 202, App. B Appendix B to Part 202—Model Application Forms 1. This appendix contains five model credit application forms, each designated for use in a...

  5. 12 CFR Appendix A to Part 213 - Model Forms

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 2 2013-01-01 2013-01-01 false Model Forms A Appendix A to Part 213 Banks and Banking FEDERAL RESERVE SYSTEM BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM CONSUMER LEASING (REGULATION M) Pt. 213, App. A Appendix A to Part 213—Model Forms A-1Model Open-End or Finance Vehicle...

  6. 12 CFR Appendix A to Part 213 - Model Forms

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 2 2014-01-01 2014-01-01 false Model Forms A Appendix A to Part 213 Banks and Banking FEDERAL RESERVE SYSTEM BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM CONSUMER LEASING (REGULATION M) Pt. 213, App. A Appendix A to Part 213—Model Forms A-1Model Open-End or Finance Vehicle...

  7. 12 CFR Appendix B to Part 1002 - Model Application Forms

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 8 2014-01-01 2014-01-01 false Model Application Forms B Appendix B to Part... B) Pt. 1002, App. B Appendix B to Part 1002—Model Application Forms 1. This appendix contains five model credit application forms, each designated for use in a particular type of consumer...

  8. 12 CFR Appendix A to Part 213 - Model Forms

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 2 2012-01-01 2012-01-01 false Model Forms A Appendix A to Part 213 Banks and Banking FEDERAL RESERVE SYSTEM BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM CONSUMER LEASING (REGULATION M) Pt. 213, App. A Appendix A to Part 213—Model Forms A-1Model Open-End or Finance Vehicle...

  9. 12 CFR Appendix B to Part 1002 - Model Application Forms

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 8 2012-01-01 2012-01-01 false Model Application Forms B Appendix B to Part... B) Pt. 1002, App. B Appendix B to Part 1002—Model Application Forms 1. This Appendix contains five model credit application forms, each designated for use in a particular type of consumer...

  10. 12 CFR Appendix B to Part 202 - Model Application Forms

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 2 2012-01-01 2012-01-01 false Model Application Forms B Appendix B to Part... CREDIT OPPORTUNITY ACT (REGULATION B) Pt. 202, App. B Appendix B to Part 202—Model Application Forms 1. This appendix contains five model credit application forms, each designated for use in a...

  11. 12 CFR Appendix B to Part 202 - Model Application Forms

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 2 2011-01-01 2011-01-01 false Model Application Forms B Appendix B to Part... CREDIT OPPORTUNITY ACT (REGULATION B) Pt. 202, App. B Appendix B to Part 202—Model Application Forms 1. This appendix contains five model credit application forms, each designated for use in a...

  12. 10 CFR Appendix K to Part 50 - ECCS Evaluation Models

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false ECCS Evaluation Models K Appendix K to Part 50 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF PRODUCTION AND UTILIZATION FACILITIES Pt. 50, App. K Appendix K to Part 50—ECCS Evaluation Models I. Required and Acceptable Features of Evaluation Models. II. Required Documentation. I. Required...

  13. 12 CFR Appendix B to Part 202 - Model Application Forms

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 2 2010-01-01 2010-01-01 false Model Application Forms B Appendix B to Part 202 Banks and Banking FEDERAL RESERVE SYSTEM BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM EQUAL CREDIT OPPORTUNITY ACT (REGULATION B) Pt. 202, App. B Appendix B to Part 202—Model Application Forms 1. This appendix contains five model...

  14. Combining acid-base, redox and substrate binding functionalities to give a complete model for the [FeFe]-hydrogenase

    PubMed Central

    Camara, James M.; Rauchfuss, Thomas B.

    2012-01-01

    Some enzymes function by coupling substrate turnover with electron transfer from a redox cofactor such as ferredoxin. In the [FeFe]-hydrogenases, nature’s fastest catalysts for the production and oxidation of H2, the one-electron redox by a ferredoxin complements the one-electron redox by the diiron active site. In this Article, we replicate the function of the ferredoxins with the redox-active ligand Cp*Fe(C5Me4CH2PEt2) (FcP*). FcP* oxidizes at mild potentials, in contrast to most ferrocene-based ligands, which suggests that it might be a useful mimic of ferredoxin cofactors. The specific model is Fe2[(SCH2)2NBn](CO)3(FcP*)(dppv) (1), which contains the three functional components of the active site: a reactive diiron centre, an amine as a proton relay and, for the first time, a one-electron redox module. By virtue of the synthetic redox cofactor, [1]2+ exhibits unique reactivity towards hydrogen and CO. In the presence of excess oxidant and base, H2 oxidation by [1]2+ is catalytic. PMID:22169868

  15. Modeling of Iron K Lines: Radiative and Auger Decay Data for Fe II-Fe IX

    NASA Technical Reports Server (NTRS)

    Palmeri, P.; Mendoza, C.; Kallman, T. R.; Bautista, M. A.; Melendez, M.

    2003-01-01

    A detailed analysis of the radiative and Auger de-excitation channels of K-shell vacancy states in Fe II-Fe IX has been carried out. Level energies, wavelengths, A-values, Auger rates and fluorescence yields have been calculated for the lowest fine-structure levels populated by photoionization of the ground state of the parent ion. Different branching ratios, namely K alpha 2/K alpha 1, K beta/K alpha, KLM/KLL, KMM/KLL, and the total K-shell fluorescence yields, omega(sub k), obtained in the present work have been compared with other theoretical data and solid-state measurements, finding good general agreement with the latter. The Kalpha 2/K alpha l ratio is found to be sensitive to the excitation mechanism. From these comparisons it has been possible to estimate an accuracy of approx.10% for the present transition probabilities.

  16. Thermodynamic Modeling and Experimental Study of the Fe-Cr-Zr System

    SciTech Connect

    Yang, Ying; Tan, Lizhen; Bei, Hongbin; Busby, Jeremy T

    2013-01-01

    Wide applications of zircaloys, stainless steels and their interactions in nuclear reactors require the knowledge on phase stability and thermodynamic property of the Fe-Cr-Zr system. This knowledge is also important to develop new Zr-contained Fe-Cr ferritic steels. This work aims at developing thermodynamic models for describing phase stability and thermodynamic property of the Fe-Cr-Zr system using the Calphad approach coupled with experimental study. Thermodynamic descriptions of the Fe-Cr and Cr-Zr systems were either directly adopted or slightly modified from literature. The Fe-Zr system has been remodeled to accommodate recent ab-initio calculation of formation enthalpies of various Fe-Zr compounds. Reliable ternary experimental data and thermodynamic models were mainly available in the Zr-rich region. Therefore, selected ternary alloys located in the vicinity of the eutectic valley of (Fe,Cr,Zr) and (Fe,Cr)2Zr laves phase in the Fe-rich region have been experimentally investigated in this study. Microstructure has been examined by using scanning electron microscope, energy-dispersive Xray spectroscopy and X-ray diffraction. These experimental results, along with the literature data were then used to develop thermodynamic models for phases in the Fe-Cr-Zr system. Calculated phase equilibria and thermodynamic properties of the ternary system yield satisfactory agreements with available experimental data, which gives the confidence to use these models as building blocks for developing a Zr, Fe and Cr contained multicomponent thermodynamic database for broader applications in nuclear reactors.

  17. 12 CFR Appendix A to Part 1013 - Model Forms

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 8 2014-01-01 2014-01-01 false Model Forms A Appendix A to Part 1013 Banks and... A to Part 1013—Model Forms A-1—Model Open-End or Finance Vehicle Lease Disclosures A-2—Model Closed-End or Net Vehicle Lease Disclosures A-3—Model Furniture Lease Disclosures ER19DE11.010...

  18. 12 CFR Appendix to Part 1016 - Model Privacy Form

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 8 2014-01-01 2014-01-01 false Model Privacy Form Appendix to Part 1016 Banks... (REGULATION P) Pt. 1016, App. Appendix to Part 1016—Model Privacy Form A. The Model Privacy Form ER21DE11.058.... How the Model Privacy Form Is Used (a) The model form may be used, at the option of a...

  19. 12 CFR Appendix A to Part 40 - Model Privacy Form

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 1 2014-01-01 2014-01-01 false Model Privacy Form A Appendix A to Part 40... INFORMATION Pt. 40, App. A Appendix A to Part 40—Model Privacy Form A. The Model Privacy Form ER01DE09.000.... How the Model Privacy Form Is Used (a) The model form may be used, at the option of a...

  20. 12 CFR Appendix A to Part 1013 - Model Forms

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 8 2013-01-01 2013-01-01 false Model Forms A Appendix A to Part 1013 Banks and... A to Part 1013—Model Forms A-1—Model Open-End or Finance Vehicle Lease Disclosures A-2—Model Closed-End or Net Vehicle Lease Disclosures A-3—Model Furniture Lease Disclosures ER19DE11.010...

  1. 12 CFR Appendix to Part 1016 - Model Privacy Form

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 8 2012-01-01 2012-01-01 false Model Privacy Form Appendix to Part 1016 Banks... (REGULATION P) Pt. 1016, App. Appendix to Part 1016—Model Privacy Form A. The Model Privacy Form ER21DE11.058.... How the Model Privacy Form Is Used (a) The model form may be used, at the option of a...

  2. 12 CFR Appendix A to Part 1013 - Model Forms

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 8 2012-01-01 2012-01-01 false Model Forms A Appendix A to Part 1013 Banks and... A to Part 1013—Model Forms A-1—Model Open-End or Finance Vehicle Lease Disclosures A-2—Model Closed-End or Net Vehicle Lease Disclosures A-3—Model Furniture Lease Disclosures ER19DE11.010...

  3. 12 CFR Appendix A to Part 40 - Model Privacy Form

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 1 2011-01-01 2011-01-01 false Model Privacy Form A Appendix A to Part 40... INFORMATION Pt. 40, App. A Appendix A to Part 40—Model Privacy Form A. The Model Privacy Form ER01DE09.000.... How the Model Privacy Form Is Used (a) The model form may be used, at the option of a...

  4. 12 CFR Appendix A to Part 40 - Model Privacy Form

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 1 2012-01-01 2012-01-01 false Model Privacy Form A Appendix A to Part 40... INFORMATION Pt. 40, App. A Appendix A to Part 40—Model Privacy Form A. The Model Privacy Form ER01DE09.000.... How the Model Privacy Form Is Used (a) The model form may be used, at the option of a...

  5. 12 CFR Appendix A to Part 40 - Model Privacy Form

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 1 2013-01-01 2013-01-01 false Model Privacy Form A Appendix A to Part 40... INFORMATION Pt. 40, App. A Appendix A to Part 40—Model Privacy Form A. The Model Privacy Form ER01DE09.000.... How the Model Privacy Form Is Used (a) The model form may be used, at the option of a...

  6. 12 CFR Appendix to Part 1016 - Model Privacy Form

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 8 2013-01-01 2013-01-01 false Model Privacy Form Appendix to Part 1016 Banks... (REGULATION P) Pt. 1016, App. Appendix to Part 1016—Model Privacy Form A. The Model Privacy Form ER21DE11.058.... How the Model Privacy Form Is Used (a) The model form may be used, at the option of a...

  7. Application of damping mechanism model and stacking fault probability in Fe-Mn alloy

    SciTech Connect

    Huang, S.K.; Wen, Y.H.; Li, N. Teng, J.; Ding, S.; Xu, Y.G.

    2008-06-15

    In this paper, the damping mechanism model of Fe-Mn alloy was analyzed using dislocation theory. Moreover, as an important parameter in Fe-Mn based alloy, the effect of stacking fault probability on the damping capacity of Fe-19.35Mn alloy after deep-cooling or tensile deformation was also studied. The damping capacity was measured using reversal torsion pendulum. The stacking fault probability of {gamma}-austenite and {epsilon}-martensite was determined by means of X-ray diffraction (XRD) profile analysis. The microstructure was observed using scanning electronic microscope (SEM). The results indicated that with the strain amplitude increasing above a critical value, the damping capacity of Fe-19.35Mn alloy increased rapidly which could be explained using the breakaway model of Shockley partial dislocations. Deep-cooling and suitable tensile deformation could improve the damping capacity owning to the increasing of stacking fault probability of Fe-19.35Mn alloy.

  8. The effectiveness of FE model for increasing accuracy in stretch forming simulation of aircraft skin panels

    NASA Astrophysics Data System (ADS)

    Kono, A.; Yamada, T.; Takahashi, S.

    2013-12-01

    In the aerospace industry, stretch forming has been used to form the outer surface parts of aircraft, which are called skin panels. Empirical methods have been used to correct the springback by measuring the formed panels. However, such methods are impractical and cost prohibitive. Therefore, there is a need to develop simulation technologies to predict the springback caused by stretch forming [1]. This paper reports the results of a study on the influences of the modeling conditions and parameters on the accuracy of an FE analysis simulating the stretch forming of aircraft skin panels. The effects of the mesh aspect ratio, convergence criteria, and integration points are investigated, and better simulation conditions and parameters are proposed.

  9. Reconstitution of [Fe]-hydrogenase using model complexes

    NASA Astrophysics Data System (ADS)

    Shima, Seigo; Chen, Dafa; Xu, Tao; Wodrich, Matthew D.; Fujishiro, Takashi; Schultz, Katherine M.; Kahnt, Jörg; Ataka, Kenichi; Hu, Xile

    2015-12-01

    [Fe]-Hydrogenase catalyses the reversible hydrogenation of a methenyltetrahydromethanopterin substrate, which is an intermediate step during the methanogenesis from CO2 and H2. The active site contains an iron-guanylylpyridinol cofactor, in which Fe2+ is coordinated by two CO ligands, as well as an acyl carbon atom and a pyridinyl nitrogen atom from a 3,4,5,6-substituted 2-pyridinol ligand. However, the mechanism of H2 activation by [Fe]-hydrogenase is unclear. Here we report the reconstitution of [Fe]-hydrogenase from an apoenzyme using two FeGP cofactor mimics to create semisynthetic enzymes. The small-molecule mimics reproduce the ligand environment of the active site, but are inactive towards H2 binding and activation on their own. We show that reconstituting the enzyme using a mimic that contains a 2-hydroxypyridine group restores activity, whereas an analogous enzyme with a 2-methoxypyridine complex was essentially inactive. These findings, together with density functional theory computations, support a mechanism in which the 2-hydroxy group is deprotonated before it serves as an internal base for heterolytic H2 cleavage.

  10. 12 CFR Appendix A to Part 213 - Model Forms

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 2 2010-01-01 2010-01-01 false Model Forms A Appendix A to Part 213 Banks and Banking FEDERAL RESERVE SYSTEM BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM CONSUMER LEASING (REGULATION M) Pt. 213, App. A Appendix A to Part 213—Model Forms A-1Model Open-End or Finance Vehicle Lease Disclosures A-2Model Closed-End or...

  11. Integrating O/S models during conceptual design, part 2

    NASA Technical Reports Server (NTRS)

    Ebeling, Charles E.

    1994-01-01

    This report documents the procedures for utilizing and maintaining the Reliability & Maintainability Model (RAM) developed by the University of Dayton for the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) under NASA research grant NAG-1-1327. The purpose of the grant is to provide support to NASA in establishing operational and support parameters and costs of proposed space systems. As part of this research objective, the model described here was developed. Additional documentation concerning the development of this model may be found in Part 1 of this report. This is the 2nd part of a 3 part technical report.

  12. 12 CFR Appendix A to Part 704 - Model Forms

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Model Forms A Appendix A to Part 704 Banks and Banking NATIONAL CREDIT UNION ADMINISTRATION REGULATIONS AFFECTING CREDIT UNIONS CORPORATE CREDIT UNIONS Pt. 704, App. A Appendix A to Part 704—Model Forms This appendix contains sample forms intended...

  13. 29 CFR Appendix A to Part 4011 - Model Participant Notice

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 9 2011-07-01 2011-07-01 false Model Participant Notice A Appendix A to Part 4011 Labor Regulations Relating to Labor (Continued) PENSION BENEFIT GUARANTY CORPORATION CERTAIN REPORTING AND DISCLOSURE REQUIREMENTS DISCLOSURE TO PARTICIPANTS Pt. 4011, App. A Appendix A to Part 4011—Model...

  14. 31 CFR Appendix A to Part 132 - Model Notice

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance: Treasury 1 2014-07-01 2014-07-01 false Model Notice A Appendix A to Part 132... 132—Model Notice Re: U.S. Unlawful Internet Gambling Enforcement Act Notice Dear : On , U.S... U.S. Code of Federal Regulations (12 CFR part 233) and part 132 of title 31 of the U.S. Code...

  15. 12 CFR Appendix A to Part 233 - Model Notice

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 4 2012-01-01 2012-01-01 false Model Notice A Appendix A to Part 233 Banks and...—Model Notice Re: U.S. Unlawful Internet Gambling Enforcement Act Notice Dear : On , U.S. government... Federal Regulations (12 CFR part 233) and part 132 of title 31 of the U.S. Code of Federal Regulations...

  16. 12 CFR Appendix A to Part 233 - Model Notice

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 4 2014-01-01 2014-01-01 false Model Notice A Appendix A to Part 233 Banks and...—Model Notice Re: U.S. Unlawful Internet Gambling Enforcement Act Notice Dear : On , U.S. government... Federal Regulations (12 CFR part 233) and part 132 of title 31 of the U.S. Code of Federal Regulations...

  17. 31 CFR Appendix A to Part 132 - Model Notice

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance: Treasury 1 2012-07-01 2012-07-01 false Model Notice A Appendix A to Part 132... 132—Model Notice Re: U.S. Unlawful Internet Gambling Enforcement Act Notice Dear : On , U.S... U.S. Code of Federal Regulations (12 CFR part 233) and part 132 of title 31 of the U.S. Code...

  18. 31 CFR Appendix A to Part 132 - Model Notice

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance: Treasury 1 2013-07-01 2013-07-01 false Model Notice A Appendix A to Part 132... 132—Model Notice Re: U.S. Unlawful Internet Gambling Enforcement Act Notice Dear : On , U.S... U.S. Code of Federal Regulations (12 CFR part 233) and part 132 of title 31 of the U.S. Code...

  19. 12 CFR Appendix A to Part 233 - Model Notice

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 4 2013-01-01 2013-01-01 false Model Notice A Appendix A to Part 233 Banks and...—Model Notice Re: U.S. Unlawful Internet Gambling Enforcement Act Notice Dear : On , U.S. government... Federal Regulations (12 CFR part 233) and part 132 of title 31 of the U.S. Code of Federal Regulations...

  20. Nucleation and phase selection in undercooled Fe-Cr-Ni melts. Part 2: Containerless solidification experiments

    SciTech Connect

    Volkmann, T.; Herlach, D.M.; Loeser, W.

    1997-02-01

    The solidification behavior of undercooled Fe-Cr-Ni melts of different compositions is investigated with respect to the competitive formation of {delta}-bcc (ferrite) and {gamma}-fcc phase (austenite). Containerless solidification experiments, electromagnetic levitation melting and drop tube experiments of atomized particles, show that {delta} (bcc) solidification is preferred in the highly undercooled melt even at compositions where {delta} is metastable. Time-resolved detection of the recalescence events during crystallization at different undercooling levels enable the determination of a critical undercooling for the transition to metastable bcc phase solidification in equilibrium fcc-type alloys. Measurements of the growth velocities of stable and metastable phases, as functions of melt undercooling prior to solidification, reveal that phase selection is controlled by nucleation. Phase selection diagrams for solidification processes as function of alloy composition and melt undercooling are derived from two types of experiments: X-ray phase analysis of quenched samples and in situ observations of the recalescence events of undercooled melts. The experimental results fit well with the theoretical predictions of the metastable phase diagram and the improved nucleation theory presented in an earlier article. In particular, the tendency of metastable {delta} phase formation in a wide composition range is confirmed.

  1. Modeling of the solubilities of NiO/NiAl2O4 and FeO/FeAl2O4 in cryolite melts at 1300 K

    NASA Astrophysics Data System (ADS)

    Zhang, Yunshu; Wu, Xiaoxia; Rapp, Robert A.

    2004-02-01

    Experiments to measure the solubilities of NiO/NiAl2O4 and FeO/FeAl2O4 were performed, and the results confirmed existing literature values. The solubilities of NiAl2O4 and FeAl2O4 in Al2O3-saturated cryolite melts at 1300 K were modeled thermodynamically in terms of the Ni-containing complexes Na2NiF4 and Na4NiF6, and the Fe-containing solutes FeF2, Na2FeF4, and Na4FeF6. The experimental solubility data were fitted to multiple simultaneous equilibria. Equilibrium constants and ΔG f 0 values for the formation reactions of the these solutes were thereby estimated. The solubilities of NiO/NiAl2O4 and FeO/FeAl2O4 and solute distributions in Al2O3-undersaturated cryolite melts were calculated for a number of melt compositions from the present model. The existence of several competitive solute species is inherent to highly buffered ionic cryolite solutions where the traditional log-log methodology had previously failed to identify dominant single solutes. In such solutions, individual solutes of oxides are not likely to dominate over a wide composition range so that a more global modeling is required. The principal solute species identified in the present study exhibit reasonable three-dimensional (3-D) anion geometries.

  2. A Minimal Two-band Model for the Superconducting Fe-pnictides

    SciTech Connect

    Raghu, S.

    2010-03-25

    Following the discovery of the Fe-pnictide superconductors, LDA band structure calculations showed that the dominant contributions to the spectral weight near the Fermi energy came from the Fe 3d orbitals. The Fermi surface is characterized by two hole surfaces around the {Lambda} point and two electron surfaces around the M point of the 2 Fe/cell Brillouin zone. Here, we describe a 2-band model that reproduces the topology of the LDA Fermi surface and exhibits both ferromagnetic and q = ({pi}, 0) spin density wave (SDW) fluctuations. We argue that this minimal model contains the essential low energy physics of these materials.

  3. The bonding of FeN2, FeCO, and Fe2N2 - Model systems for side-on bonding of CO and N2

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Pettersson, Lars G. M.; Siegbahn, Per E. M.

    1987-01-01

    Qualitative calculations are performed to elucidate the nature of the side-on interaction of both N2 and CO with a single Fe atom. The systems are found to be quite similar, with bonding leading to an increase in the CO or N2 bond length and a decrease in the vibrational frequency. The CO or N2 stretching modes lead to a large dipole derivative along the metal-ligand bond axis. The populations show an almost identical, large donation from the Fe 3d orbitals into the CO or N2 Pi-asterisk. The larger system Fe2N2 is then considered, with the N2 bridging the Fe2, both parallel and perpendicular to the Fe2 bond axis for two different Fe-Fe distances. For FeN2, the shift in the observed N2 frequency is smaller than observed for the alpha state of N2/Fe(111). The shift in the N2 vibrational frequency increases when the N2 interacts with two Fe atoms, either at the Fe-Fe nearest neighbor distance or at the first layer Fe-Fe distance, when the side-on N2 axis is oriented perpendicular to an Fe-Fe bond.

  4. 12 CFR Appendix A to Part 216 - Model Privacy Form

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 2 2012-01-01 2012-01-01 false Model Privacy Form A Appendix A to Part 216... CONSUMER FINANCIAL INFORMATION (REGULATION P) Pt. 216, App. A Appendix A to Part 216—Model Privacy Form A. The Model Privacy Form ER01DE09.007 ER01DE09.008 ER01DE09.009 ER01DE09.010 ER01DE09.011...

  5. 12 CFR Appendix A to Part 332 - Model Privacy Form

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 4 2011-01-01 2011-01-01 false Model Privacy Form A Appendix A to Part 332... PRIVACY OF CONSUMER FINANCIAL INFORMATION Pt. 332, App. A Appendix A to Part 332—Model Privacy Form A. The Model Privacy Form ER01DE09.014 ER01DE09.015 ER01DE09.016 ER01DE09.017 ER01DE09.018...

  6. 12 CFR Appendix A to Part 216 - Model Privacy Form

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 2 2011-01-01 2011-01-01 false Model Privacy Form A Appendix A to Part 216... CONSUMER FINANCIAL INFORMATION (REGULATION P) Pt. 216, App. A Appendix A to Part 216—Model Privacy Form A. The Model Privacy Form ER01DE09.007 ER01DE09.008 ER01DE09.009 ER01DE09.010 ER01DE09.011...

  7. 12 CFR Appendix A to Part 332 - Model Privacy Form

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 5 2013-01-01 2013-01-01 false Model Privacy Form A Appendix A to Part 332... PRIVACY OF CONSUMER FINANCIAL INFORMATION Pt. 332, App. A Appendix A to Part 332—Model Privacy Form A. The Model Privacy Form ER01DE09.014 ER01DE09.015 ER01DE09.016 ER01DE09.017 ER01DE09.018...

  8. 12 CFR Appendix A to Part 332 - Model Privacy Form

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 5 2014-01-01 2014-01-01 false Model Privacy Form A Appendix A to Part 332... PRIVACY OF CONSUMER FINANCIAL INFORMATION Pt. 332, App. A Appendix A to Part 332—Model Privacy Form A. The Model Privacy Form ER01DE09.014 ER01DE09.015 ER01DE09.016 ER01DE09.017 ER01DE09.018...

  9. 12 CFR Appendix A to Part 216 - Model Privacy Form

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 2 2013-01-01 2013-01-01 false Model Privacy Form A Appendix A to Part 216... CONSUMER FINANCIAL INFORMATION (REGULATION P) Pt. 216, App. A Appendix A to Part 216—Model Privacy Form A. The Model Privacy Form ER01DE09.007 ER01DE09.008 ER01DE09.009 ER01DE09.010 ER01DE09.011...

  10. 12 CFR Appendix A to Part 216 - Model Privacy Form

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 2 2014-01-01 2014-01-01 false Model Privacy Form A Appendix A to Part 216... CONSUMER FINANCIAL INFORMATION (REGULATION P) Pt. 216, App. A Appendix A to Part 216—Model Privacy Form A. The Model Privacy Form ER01DE09.007 ER01DE09.008 ER01DE09.009 ER01DE09.010 ER01DE09.011...

  11. 12 CFR Appendix A to Part 332 - Model Privacy Form

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 5 2012-01-01 2012-01-01 false Model Privacy Form A Appendix A to Part 332... PRIVACY OF CONSUMER FINANCIAL INFORMATION Pt. 332, App. A Appendix A to Part 332—Model Privacy Form A. The Model Privacy Form ER01DE09.014 ER01DE09.015 ER01DE09.016 ER01DE09.017 ER01DE09.018...

  12. Enhanced Stability of the Fe(II)/Mn(II) State in a Synthetic Model of Heterobimetallic Cofactor Assembly.

    PubMed

    Kerber, William D; Goheen, Joshua T; Perez, Kaitlyn A; Siegler, Maxime A

    2016-01-19

    Heterobimetallic Mn/Fe cofactors are found in the R2 subunit of class Ic ribonucleotide reductases (R2c) and R2-like ligand binding oxidases (R2lox). Selective cofactor assembly is due at least in part to the thermodynamics of M(II) binding to the apoprotein. We report here equilibrium studies of Fe(II)/Mn(II) discrimination in the biomimetic model system H5(F-HXTA) (5-fluoro-2-hydroxy-1,3-xylene-α,α'-diamine-N,N,N',N'-tetraacetic acid). The homobimetallic F-HXTA complexes [Fe(H2O)6][1]2·14H2O and [Mn(H2O)6][2]2·14H2O (1 = [Fe(II)2(F-HXTA)(H2O)4](-); 2 = [Mn(II)2(F-HXTA)(H2O)4](-)) were characterized by single crystal X-ray diffraction. NMR data show that 1 retains its structure in solution (2 is NMR silent). Metal exchange is facile, and the heterobimetallic complex [Fe(II)Mn(II)(F-HXTA)(H2O)4](-) (3) is formed from mixtures of 1 and 2. (19)F NMR was used to quantify 1 and 3 in the presence of excess M(II)(aq) at various metal ratios, and equilibrium constants for Fe(II)/Mn(II) discrimination were calculated from these data. Fe(II) is preferred over Mn(II) with K1 = 182 ± 13 for complete replacement (2 ⇌ 1). This relatively modest preference is attributed to a hard-soft acid-base mismatch between the divalent cations and the polycarboxylate ligand. The stepwise constants for replacement are K2 = 20.1 ± 1.3 (2 ⇌ 3) and K3 = 9.1 ± 1.1 (3 ⇌ 1). K2 > K3 demonstrates enhanced stability of the heterobimetallic state beyond what is expected for simple Mn(II) → Fe(II) replacement. The relevance to Fe(II)/Mn(II) discrimination in R2c and R2lox proteins is discussed. PMID:26709740

  13. Astronaut Bone Medical Standards Derived from Finite Element (FE) Models of QCT Scans from Population Studies

    NASA Technical Reports Server (NTRS)

    Sibonga, J. D.; Feiveson, A. H.

    2014-01-01

    This work was accomplished in support of the Finite Element [FE] Strength Task Group, NASA Johnson Space Center [JSC], Houston, TX. This group was charged with the task of developing rules for using finite-element [FE] bone-strength measures to construct operating bands for bone health that are relevant to astronauts following exposure to spaceflight. FE modeling is a computational tool used by engineers to estimate the failure loads of complex structures. Recently, some engineers have used this tool to characterize the failure loads of the hip in population studies that also monitored fracture outcomes. A Directed Research Task was authorized in July, 2012 to investigate FE data from these population studies to derive these proposed standards of bone health as a function of age and gender. The proposed standards make use of an FE-based index that integrates multiple contributors to bone strength, an expanded evaluation that is critical after an astronaut is exposed to spaceflight. The current index of bone health used by NASA is the measurement of areal BMD. There was a concern voiced by a research and clinical advisory panel that the sole use of areal BMD would be insufficient to fully evaluate the effects of spaceflight on the hip. Hence, NASA may not have a full understanding of fracture risk, both during and after a mission, and may be poorly estimating in-flight countermeasure efficacy. The FE Strength Task Group - composed of principal investigators of the aforementioned population studies and of FE modelers -donated some of its population QCT data to estimate of hip bone strength by FE modeling for this specific purpose. Consequently, Human Health Countermeasures [HHC] has compiled a dataset of FE hip strengths, generated by a single FE modeling approach, from human subjects (approx.1060) with ages covering the age range of the astronauts. The dataset has been analyzed to generate a set of FE strength cutoffs for the following scenarios: a) Qualify an

  14. High-resolution measurements, line identification, and spectral modeling of K-alpha transitions in Fe XVIII-Fe XXV

    NASA Technical Reports Server (NTRS)

    Beiersdorfer, P.; Phillips, T.; Jacobs, V. L.; Hill, K. W.; Bitter, M.; Von Goeler, S.; Kahn, S. M.

    1993-01-01

    A detailed analysis of the iron K-alpha emission spectrum covering the wavelength region from 1.840 to 1.940 A is presented. Measurements are made with a high-resolution Bragg crystal spectrometer on the Princeton Large Torus (PLT) tokamak for plasma conditions which closely resemble those of solar flares. A total of 40 features are identified, consisting of either single or multiple lines from eight charge states in iron, Fe XVIII - Fe XXV, and their wavelengths are determined with an accuracy of 0.1-0.4 mA. Many of these features are identified for the first time. In the interpretation of our observations we rely on model calculations that determine the ionic species abundances from electron density and temperature profiles measured independently with nonspectroscopic techniques and that incorporate theoretical collisional excitation and dielectronic recombination rates resulting in the excitation of the 1s2sr2ps configurations. The model calculations also include the effect of diffusive ion transport. Good overall agreement between the model calculations and the observations is obtained, which gives us confidence in our line identifications and spectral modeling capabilities. The results are compared with earlier analyses of the K-alpha emission from the Sun.

  15. Multistage growth of Fe-Mg-carpholite and Fe-Mg-chloritoid, from field evidence to thermodynamic modelling

    NASA Astrophysics Data System (ADS)

    Pourteau, Amaury; Bousquet, Romain; Vidal, Olivier; Plunder, Alexis; Duesterhoeft, Erik; Candan, Osman; Oberhänsli, Roland

    2015-04-01

    We provide new insights into the prograde evolution of HP/LT meta-sedimentary rocks on the basis of detailed petrologic examination, element-partitioning analysis, and thermodynamic modelling of well-preserved Fe-Mg-carpholite- and chloritoid-bearing rocks from the Afyon zone (Anatolia). Study samples, stemming from three different areas of the metamorphic belt, include typical quartz-carpholite veins as well as quartz-free and quartz-bearing phyllites. All samples exhibit multiple stages of carpholite, whereas zoning was until now rarely documented in this type of rocks. We document continuous, and discontinuous compositional (ferro-magnesian substitution) zoning of carpholite (overall XMg = 0.27-0.73) and chloritoid (overall XMg = 0.07-0.30), as well as clear equilibrium, and disequilibrium (i.e. reaction-related) textures involving carpholite and chloritoid, which consistently account for the consistent enrichment in Mg of both minerals through time, and the progressive replacement of carpholite by chloritoid. Mg/Fe distribution coefficients calculated between carpholite and chloritoid vary widely within samples (2.2-20.0). Among this range, only values of 7-11 correlate with equilibrium textures, in agreement with data from the literature. Equilibrium phase diagrams for (NaK)FMASH rock compositions are calculated using a newly modified thermodynamic dataset, including most recent data for carpholite, chloritoid, chlorite, and white mica, as well as further refinements for Fe-carpholite, and both chloritoid end-members, as required to reproduce accurately petrologic observations (phase relations, experimental constraints, Mg/Fe partitioning). Modelling reveals that Mg/Fe partitioning between carpholite and chloritoid is greatly sensitive to temperature, and calls for a future evaluation of possible use as a thermometer, valid for blueschist-facies conditions, which has so far been missing. In addition, calculations show significant effective bulk composition

  16. Development of Simultaneous Corrosion Barrier and Optimized Microstructure in FeCrAl Heat-Resistant Alloy for Energy Applications. Part 1: The Protective Scale

    NASA Astrophysics Data System (ADS)

    Pimentel, G.; Aranda, M. M.; Chao, J.; González-Carrasco, J. L.; Capdevila, C.

    2015-09-01

    Coarse-grained Fe-based oxide dispersion-strengthened (ODS) steels are a class of advanced materials for combined cycle gas turbine systems to deal with operating temperatures and pressures of around 1100°C and 15-30 bar in aggressive environments, which would increase biomass energy conversion efficiencies up to 45% and above. This two-part paper reports the possibility of the development of simultaneous corrosion barrier and optimized microstructure in a FeCrAl heat-resistant alloy for energy applications. The first part reports the mechanism of generating a dense, self-healing α-alumina layer by thermal oxidation, during a heat treatment that leads to a coarse-grained microstructure with a potential value for high-temperature creep resistance in a FeCrAl ODS ferritic alloy, which will be described in more detail in the second part.

  17. Precise Opacities for Astrophysics (Fe and Ni) and ICF modeling

    NASA Astrophysics Data System (ADS)

    Klapisch, Marcel; Gilles, Dominique; Busquet, Michel

    2015-11-01

    Opacities of FeIII - FeXV at Te =15-20 eV and densities 1.e16-1.e23 cm-3 have been computed with an improved version of the HULLAC code. More than 109 transitions have been computed, with different ways to account for configuration interactions (CI). Spectra with CI limited to each non-relativistic configuration (CIinNRC) are compared to more extended full Relativistic CI (RCI). The effect of increasing the size of the CI basis is investigated. These comparisons enable optimizing the method for each temperature/density regime. With powerful computers, HULLAC -generated opacity databases could then be envisioned, bypassing the need for statistical approximations.

  18. Fe-Radiation-Induced Alterations in Circulating Leukocyte Populations in the ApoE Mouse Atherosclerosis Model are Temporary

    NASA Astrophysics Data System (ADS)

    Yu, Tao; Yu, Shaohua; Parks, Brian W.; Gupta, Kiran; Wu, Xing; Khaled, Saman; Chang, Polly Y.; Srivastava, Roshni; Kabarowski, Janusz H. S.; Kucik, Dennis F.

    2008-06-01

    Radiation is associated with an increased risk of heart disease and stroke, likely due in part to vascular inflammation. One model used to understand this is the apoE mouse, where gamma irradiation accelerates development of atherosclerosis. Less is known, though, about the effects of high linear energy transfer (LET) radiation, such as 56Fe, likely to be encountered by astronauts in deep space. Radiation, however, also affects leukocyte numbers. For example, whole-body 56Fe irradiation has been shown to decrease circulating B-cells and T-cells, but whether this was due to radiation of the thymus, of the bone marrow, or both was not determined. We irradiated ApoE mice with 56Fe focused to the aorta and carotids to determine how irradiation of the thymus with 56Fe affects circulating lymphocyte number, and ultimately to determine the effect of iron ion irradiation on development of atherosclerosis. We found that only T-cells were affected at 13 weeks post-irradiation, but even these recovered at 40 weeks, suggesting that effects on the immune system are limited and temporary. Analysis of atherosclerosis development is pending sacrifice and histological analysis of irradiated mice.

  19. Reaction Mechanisms of Metals with Hydrogen Sulfide and Thiols in Model Wine. Part 2: Iron- and Copper-Catalyzed Oxidation.

    PubMed

    Kreitman, Gal Y; Danilewicz, John C; Jeffery, David W; Elias, Ryan J

    2016-05-25

    Sulfidic off-odors arising during wine production are frequently removed by Cu(II) fining. In part 1 of this study ( 10.1021/acs.jafc.6b00641 ), the reaction of H2S and thiols with Cu(II) was examined; however, the interaction of iron and copper is also known to play an important synergistic role in mediating non-enzymatic wine oxidation. The interaction of these two metals in the oxidation of H2S and thiols (cysteine, 3-sulfanylhexan-1-ol, and 6-sulfanylhexan-1-ol) was therefore examined under wine-like conditions. H2S and thiols (300 μM) were reacted with Fe(III) (100 or 200 μM) alone and in combination with Cu(II) (25 or 50 μM), and concentrations of H2S and thiols, oxygen, and acetaldehyde were monitored over time. H2S and thiols were shown to be slowly oxidized in the presence of Fe(III) alone and were not bound to Fe(III) under model wine conditions. However, Cu(II) added to model wine containing Fe(III) was quickly reduced by H2S and thiols to form Cu(I) complexes, which then rapidly reduced Fe(III) to Fe(II). Oxidation of Fe(II) in the presence of oxygen regenerated Fe(III) and completed the iron redox cycle. In addition, sulfur-derived oxidation products were observed, and the formation of organic polysulfanes was demonstrated. PMID:27133088

  20. Materials Chemistry of BaFe2As2: A Model Platform for Unconventional Superconductivity

    SciTech Connect

    Mandrus, David; Safa-Sefat, Athena; McGuire, Michael A; Sales, Brian C

    2010-01-01

    BaFe{sub 2}As{sub 2} is the parent compound of a family of unconventional superconductors with critical temperatures approaching 40 K. BaFe{sub 2}As{sub 2} is structurally simple, available as high-quality large crystals, can be both hole and electron doped, and is amenable to first-principles electronic structure calculations. BaFe{sub 2}As{sub 2} has a rich and flexible materials chemistry that makes it an ideal model platform for the study of unconventional superconductivity. The key properties of this family of materials are briefly reviewed.

  1. Model evaporation of FeO-bearing liquids: Application to chondrules

    NASA Astrophysics Data System (ADS)

    Ebel, Denton S.

    2005-06-01

    Models for thermodynamic behavior of FeO-bearing liquids are required for understanding the separate roles of evaporation, condensation and crystallization in the formation of free-floating silicate liquid droplets in the early solar nebula. These droplets, frozen as chondrules, are common in chondritic meteorites. Evaporation coefficients for Fe and FeO of ˜0.2 are calculated here from existing data using silicate liquid activity models. These models, used to describe gas-liquid-solid equilibria and to constrain kinetic processes, are compared and found similar, and the effects of liquid non-ideality are assessed. A general approach is presented for predicting the evaporation behavior of FeO-bearing Al 2O 3-CaO-SiO 2-MgO liquids in H 2-rich gas above 1400 K at low total pressure. Results are vapor pressure curves for Fe, FeO and other gas species above typical chondrule liquids, suitable for predicting compositional trajectories of residual liquids evaporating in a hydrogen-dominated vapor. These predictions are consistent with chondrule formation in the protoplanetary disk in heating events of short duration, such as those expected from shock wave or current sheet models.

  2. A joint model for boundaries of multiple anatomical parts

    NASA Astrophysics Data System (ADS)

    Kerr, Grégoire; Kurtek, Sebastian; Srivastava, Anuj

    2011-03-01

    The use of joint shape analysis of multiple anatomical parts is a promising area of research with applications in medical diagnostics, growth evaluations, and disease characterizations. In this paper, we consider several features (shapes, orientations, scales, and locations) associated with anatomical parts and develop probability models that capture interactions between these features and across objects. The shape component is based on elastic shape analysis of continuous boundary curves. The proposed model is a second order model that considers principal coefficients in tangent spaces of joint manifolds as multivariate normal random variables. Additionally, it models interactions across objects using area-interaction processes. Using given observations of four anatomical parts: caudate, hippocampus, putamen and thalamus, on one side of the brain, we first estimate the model parameters and then generate random samples from them using the Metropolis-Hastings algorithm. The plausibility of these random samples validates the proposed models.

  3. Radiation transport phenomena and modeling. Part A: Codes; Part B: Applications with examples

    SciTech Connect

    Lorence, L.J. Jr.; Beutler, D.E.

    1997-09-01

    This report contains the notes from the second session of the 1997 IEEE Nuclear and Space Radiation Effects Conference Short Course on Applying Computer Simulation Tools to Radiation Effects Problems. Part A discusses the physical phenomena modeled in radiation transport codes and various types of algorithmic implementations. Part B gives examples of how these codes can be used to design experiments whose results can be easily analyzed and describes how to calculate quantities of interest for electronic devices.

  4. Catalytic conversion of nitrogen to ammonia by a molecular Fe model complex

    PubMed Central

    Anderson, John S.; Rittle, Jonathan; Peters, Jonas C.

    2013-01-01

    The reduction of N2 to NH3 is a requisite transformation for life.1 While it is widely appreciated that the iron-rich cofactors of nitrogenase enzymes facilitate this transformation,2-5 how they do so remains poorly understood. A central element of debate has been the exact site(s) of nitrogen coordination and reduction.6,7 The synthetic inorganic community placed an early emphasis on Mo8, because Mo was thought to be an essential element of nitrogenases3 and because pioneering work by Chatt and coworkers established that well-defined Mo model complexes could mediate the stoichiometric conversion of N2 to NH3.9 This chemical transformation can be performed in a catalytic fashion by two well-defined molecular systems that feature Mo centres.10,11 However, it is now thought that Fe is the only transition metal essential to all nitrogenases,3 and recent biochemical and spectroscopic data has implicated Fe instead of Mo as the site of N2 binding in the FeMo-cofactor.12 In this work, we describe a tris(phosphine)borane-supported Fe complex that catalyzes the reduction of N2 to NH3 under mild conditions, wherein >40% of the H+/e- equivalents are delivered to N2. Our results indicate that a single Fe site may be capable of stabilizing the various NxHy intermediates generated en route to catalytic NH3 formation. Geometric tunability at Fe imparted by a flexible Fe-B interaction in our model system appears to be important for efficient catalysis.13-15 We propose that the interstitial light C-atom recently assigned in the nitrogenase cofactor may play a similar role,16,17 perhaps by enabling a single Fe site to mediate the enzymatic catalysis via a flexible Fe-C interaction.18 PMID:24005414

  5. 16 CFR Appendix A to Part 313 - Model Privacy Form

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Model Privacy Form A Appendix A to Part 313... FINANCIAL INFORMATION Pt. 313, App. A Appendix A to Part 313—Model Privacy Form A. The Model Privacy Form ER01DE09.035 ER01DE09.036 ER01DE09.037 ER01DE09.038 ER01DE09.039 ER01DE09.041 1. How the Model Privacy...

  6. 16 CFR Appendix A to Part 313 - Model Privacy Form

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Model Privacy Form A Appendix A to Part 313... FINANCIAL INFORMATION Pt. 313, App. A Appendix A to Part 313—Model Privacy Form A. The Model Privacy Form ER01DE09.035 ER01DE09.036 ER01DE09.037 ER01DE09.038 ER01DE09.039 ER01DE09.041 1. How the Model Privacy...

  7. 16 CFR Appendix A to Part 313 - Model Privacy Form

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 1 2013-01-01 2013-01-01 false Model Privacy Form A Appendix A to Part 313... FINANCIAL INFORMATION Pt. 313, App. A Appendix A to Part 313—Model Privacy Form A. The Model Privacy Form ER01DE09.035 ER01DE09.036 ER01DE09.037 ER01DE09.038 ER01DE09.039 ER01DE09.041 1. How the Model Privacy...

  8. 16 CFR Appendix A to Part 313 - Model Privacy Form

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 1 2012-01-01 2012-01-01 false Model Privacy Form A Appendix A to Part 313... FINANCIAL INFORMATION Pt. 313, App. A Appendix A to Part 313—Model Privacy Form A. The Model Privacy Form ER01DE09.035 ER01DE09.036 ER01DE09.037 ER01DE09.038 ER01DE09.039 ER01DE09.041 1. How the Model Privacy...

  9. 16 CFR Appendix A to Part 313 - Model Privacy Form

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Model Privacy Form A Appendix A to Part 313... FINANCIAL INFORMATION Pt. 313, App. A Appendix A to Part 313—Model Privacy Form A. The Model Privacy Form ER01DE09.035 ER01DE09.036 ER01DE09.037 ER01DE09.038 ER01DE09.039 ER01DE09.041 1. How the Model Privacy...

  10. Self-Consistent Model for Planar Ferrite Growth in Fe-C-X Alloys

    NASA Astrophysics Data System (ADS)

    Zurob, H. S.; Panahi, D.; Hutchinson, C. R.; Brechet, Y.; Purdy, G. R.

    2013-08-01

    A self-consistent model for non-partitioning planar ferrite growth from alloyed austenite is presented. The model captures the evolution with time of interfacial contact conditions for substitutional and interstitial solutes. Substitutional element solute drag is evaluated in terms of the dissipation of free energy within the interface, and an estimate is provided for the rate of buildup of the alloying element "spike" in austenite. The transport of the alloying elements within the interface region is modeled using a discrete-jump model, while the bulk diffusion of C is treated using a standard continuum treatment. The model is validated against ferrite precipitation and decarburization kinetics in the Fe-Ni-C, Fe-Mn-C, and Fe-Mo-C systems.

  11. Integrating O/S models during conceptual design, part 1

    NASA Technical Reports Server (NTRS)

    Ebeling, Charles E.

    1994-01-01

    The University of Dayton is pleased to submit this report to the National Aeronautics and Space Administration (NASA), Langley Research Center, which integrates a set of models for determining operational capabilities and support requirements during the conceptual design of proposed space systems. This research provides for the integration of the reliability and maintainability (R&M) model, both new and existing simulation models, and existing operations and support (O&S) costing equations in arriving at a complete analysis methodology. Details concerning the R&M model and the O&S costing model may be found in previous reports accomplished under this grant (NASA Research Grant NAG1-1327). In the process of developing this comprehensive analysis approach, significant enhancements were made to the R&M model, updates to the O&S costing model were accomplished, and a new simulation model developed. This is the 1st part of a 3 part technical report.

  12. SHM-Based Probabilistic Fatigue Life Prediction for Bridges Based on FE Model Updating.

    PubMed

    Lee, Young-Joo; Cho, Soojin

    2016-01-01

    Fatigue life prediction for a bridge should be based on the current condition of the bridge, and various sources of uncertainty, such as material properties, anticipated vehicle loads and environmental conditions, make the prediction very challenging. This paper presents a new approach for probabilistic fatigue life prediction for bridges using finite element (FE) model updating based on structural health monitoring (SHM) data. Recently, various types of SHM systems have been used to monitor and evaluate the long-term structural performance of bridges. For example, SHM data can be used to estimate the degradation of an in-service bridge, which makes it possible to update the initial FE model. The proposed method consists of three steps: (1) identifying the modal properties of a bridge, such as mode shapes and natural frequencies, based on the ambient vibration under passing vehicles; (2) updating the structural parameters of an initial FE model using the identified modal properties; and (3) predicting the probabilistic fatigue life using the updated FE model. The proposed method is demonstrated by application to a numerical model of a bridge, and the impact of FE model updating on the bridge fatigue life is discussed. PMID:26950125

  13. SHM-Based Probabilistic Fatigue Life Prediction for Bridges Based on FE Model Updating

    PubMed Central

    Lee, Young-Joo; Cho, Soojin

    2016-01-01

    Fatigue life prediction for a bridge should be based on the current condition of the bridge, and various sources of uncertainty, such as material properties, anticipated vehicle loads and environmental conditions, make the prediction very challenging. This paper presents a new approach for probabilistic fatigue life prediction for bridges using finite element (FE) model updating based on structural health monitoring (SHM) data. Recently, various types of SHM systems have been used to monitor and evaluate the long-term structural performance of bridges. For example, SHM data can be used to estimate the degradation of an in-service bridge, which makes it possible to update the initial FE model. The proposed method consists of three steps: (1) identifying the modal properties of a bridge, such as mode shapes and natural frequencies, based on the ambient vibration under passing vehicles; (2) updating the structural parameters of an initial FE model using the identified modal properties; and (3) predicting the probabilistic fatigue life using the updated FE model. The proposed method is demonstrated by application to a numerical model of a bridge, and the impact of FE model updating on the bridge fatigue life is discussed. PMID:26950125

  14. 17 CFR Appendix A to Part 160 - Model Privacy Form

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 1 2013-04-01 2013-04-01 false Model Privacy Form A Appendix... Part 160—Model Privacy Form A. The Model Privacy Form ER28DE12.003 ER28DE12.004 ER28DE12.005 ER28DE12.006 ER28DE12.007 ER28DE12.008 ER28DE12.009 B. General Instructions 1. How the Model Privacy Form...

  15. Modelling of stamping of DP steel automotive part accounting for the effect of hard components in the microstructure

    NASA Astrophysics Data System (ADS)

    Ambrozinski, Mateusz; Bzowski, Krzysztof; Mirek, Michal; Rauch, Lukasz; Pietrzyk, Maciej

    2013-05-01

    The paper presents simulations of the manufacturing of the automotive part, which has high influence on improvement of passengers safety. Two approaches to the Finite Element (FE) modelling of stamping of a part that provides extra stiffening of construction subassemblies in the back of a car were considered. The first is conventional simulation, which assumes that the material is a continuum with flow stress model and anisotropy coefficients determined from the tensile tests. In the second approach two-phase microstructure of the DP steel is accounted for in simulations. The FE2 method, which belongs to upscaling techniques, is used. Representative Volume Element (RVE), which is the basis of the upscaling approach and reflects the real microstructure, was obtained by the image analysis of the micrograph of the DP steel. However, since FE2 simulations with the real picture of the microstructure in the micro scale, are extremely time consuming, the idea of the Statistically Similar Representative Volume Element (SSRVE) was applied. SSRVE obtained for the DP steel, used for production of automotive part, is presented in the paper in the form of 3D inclusion. The macro scale model of the simulated part is described in details, as well as the results obtained for macro and micro-macro simulations.

  16. Decoupling of As and Fe release to Bangladesh groundwater under reducing conditions. Part I: Evidence from sediment profiles

    NASA Astrophysics Data System (ADS)

    Horneman, A.; van Geen, A.; Kent, D. V.; Mathe, P. E.; Zheng, Y.; Dhar, R. K.; O'Connell, S.; Hoque, M. A.; Aziz, Z.; Shamsudduha, M.; Seddique, A. A.; Ahmed, K. M.

    2004-09-01

    This study reexamines the notion that extensive As mobilization in anoxic groundwater of Bangladesh is intimately linked to the dissolution of Fe oxyhydroxides on the basis of analyses performed on a suite of freshly collected samples of aquifer material. Detailed sediment profiles extending to 40 to 70 m depth below the surface were obtained at six sites where local groundwater As concentrations were known to span a wide range. The sediment properties that were measured include (1) the proportion of Fe(II) in the Fe fraction leached in hot 1.2 N HCl, (2) diffuse spectral reflectance, and (3) magnetic susceptibility. In parallel with local concentrations of dissolved As ranging from <5 to 600 μg/L, Fe(II)/Fe ratios in shallow (gray) Holocene sands tended to gradually increase with depth from values of 0.3 to 0.5 to up to 0.9. In deeper (orange) aquifers of presumed Pleistocene age that were separated from shallow sands by a clay layer and contained <5 μg/L dissolved As, leachable Fe(II)/Fe ratios averaged ˜0.2. There was no consistent relation between sediment Fe(II)/Fe and dissolved Fe concentrations in groundwater in nearby wells. The reflectance measurements indicate a systematic linear relation (R 2 of 0.66; n = 151) between the first derivative transform of the reflectance at 520 nm and Fe(II)/Fe. The magnetic susceptibility of the shallow aquifer sands ranged from 200 to 3600 (x 10 -9 m 3/kg SI) and was linearly related (R 2 of 0.75; n = 29) to the concentrations of minerals that could be magnetically separated (0.03 to 0.79% dry weight). No systematic depth trends in magnetic susceptibility were observed within the shallow sands, although the susceptibility of deeper low-As aquifers was low (up to ˜200 × 10 -9 m 3/kg SI). This set of observations, complemented by incubation results described in a companion paper by van Geen et al. (this volume), suggests that the release of As is linked to the transformation of predominantly Fe (III) oxyhydroxide

  17. Synthetic Active Site Model of the [NiFeSe] Hydrogenase

    PubMed Central

    Wombwell, Claire; Reisner, Erwin

    2015-01-01

    A dinuclear synthetic model of the [NiFeSe] hydrogenase active site and a structural, spectroscopic and electrochemical analysis of this complex is reported. [NiFe(‘S2Se2’)(CO)3] (H2‘S2Se2’=1,2-bis(2-thiabutyl-3,3-dimethyl-4-selenol)benzene) has been synthesized by reacting the nickel selenolate complex [Ni(‘S2Se2’)] with [Fe(CO)3bda] (bda=benzylideneacetone). X-ray crystal structure analysis confirms that [NiFe(‘S2Se2’)(CO)3] mimics the key structural features of the enzyme active site, including a doubly bridged heterobimetallic nickel and iron center with a selenolate terminally coordinated to the nickel center. Comparison of [NiFe(‘S2Se2’)(CO)3] with the previously reported thiolate analogue [NiFe(‘S4’)(CO)3] (H2‘S4’=H2xbsms=1,2-bis(4-mercapto-3,3-dimethyl-2-thiabutyl)benzene) showed that the selenolate groups in [NiFe(‘S2Se2’)(CO)3] give lower carbonyl stretching frequencies in the IR spectrum. Electrochemical studies of [NiFe(‘S2Se2’)(CO)3] and [NiFe(‘S4’)(CO)3] demonstrated that both complexes do not operate as homogenous H2 evolution catalysts, but are precursors to a solid deposit on an electrode surface for H2 evolution catalysis in organic and aqueous solution. PMID:25847470

  18. Intergenerational Educational Encounters: Part 2--Counseling Implications of the Model

    ERIC Educational Resources Information Center

    Gamliel, Tova; Reichental, Yael; Eyal, Nitza

    2007-01-01

    This second paper commences where Part 1 concluded in volume 33, number 1, 2006. The paper describes the relations reflected in the Model-of-Knowledge between all partners of the intergenerational encounters at school--children, old adults, and teachers. The Model-of-Knowledge represents a relatively balanced approach toward the generations'…

  19. Twin nucleation in Fe-based bcc alloys—modeling and experiments

    NASA Astrophysics Data System (ADS)

    Ojha, A.; Sehitoglu, H.; Patriarca, L.; Maier, H. J.

    2014-10-01

    We develop an analytical expression for twin nucleation stress in bcc metal and alloys considering generalized planar fault energy and the dislocations bounding the twin nucleus. We minimize the total energy to predict the twinning stress relying only on parameters that are obtained through atomistic calculations, thus excluding the need for any empirical constants. We validate the present approach by means of precise measurements of the onset of twinning in bcc Fe-50at% Cr single crystals showing excellent agreement. The experimental observations of the three activated slip systems of symmetric configuration in relation to the twinning mechanism are demonstrated via transmission electron microscopy techniques along with digital image correlation. We then confirm the validity of the model for Fe, Fe-25at% Ni and Fe-3at% V alloys compared with experiments from the literature to show general applicability.

  20. Reaction-Based Reactive Transport Modeling of Fe(III) and U(V) Reduction

    SciTech Connect

    Burgos, William D.; Roden, Eric E.; Yeh, Gour-Tsyh

    2005-06-01

    Our new research project (started Fall 2004) was funded by a grant to The Pennsylvania State University, University of Central Florida, and The University of Alabama in the Integrative Studies Element of the NABIR Program (DE-FG04-ER63914/63915/63196). Our previous NABIR project (DE-FG02-01ER63180/63181/63182, funded within the Biotransformation Element) focused on (1) microbial reduction of Fe(III) and U(VI) individually, and concomitantly in natural sediments, (2) Fe(III) oxide surface chemistry, specifically with respect to reactions with Fe(II) and U(VI), (3) the influence of humic substances on Fe(III) and U(VI) bioreduction, and on U(VI) complexation, and (4) the development of reaction-based reactive transport biogeochemical models to numerically simulate our experimental results. The new project focuses on the development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. This work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and is directly aligned with the Scheibe et al. NABIR FRC Field Project at Area 2.

  1. H2 binding and splitting on a new-generation [FeFe]-hydrogenase model featuring a redox-active decamethylferrocenyl phosphine ligand: a theoretical investigation.

    PubMed

    Greco, Claudio

    2013-02-18

    [FeFe]-hydrogenases are dihydrogen-evolving metalloenzymes that are able to combine substrate binding and redox functionalities, a feature that has important bearing on their efficiency. New-generation bioinspired systems such as Fe(2)[(SCH(2))(2)NBn](CO)(3)(Cp*Fe(C(5)Me(4)CH(2)PEt(2)))(dppv) were shown to mimic H(2) oxidation and splitting processes performed by the [FeFe]-hydrogenase/ferredoxin system, and key mechanistic aspects of such reaction are theoretically investigated in the present contribution. We found that H(2) binding and heterolytic cleavage take place concomitantly on DFT models of the synthetic catalyst, due to a substrate-dependent intramolecular redox process that promotes dihydrogen activation. Therefore, formation of an iron-dihydrogen complex as a reaction intermediate is excluded in the biomimetic system, at variance with the case of the enzyme. H(2) uptake at the synthetic system also requires an energetically disfavored isomerization of the amine group acting as a base during splitting. A possible strategy to stabilize the conformation competent for H(2) binding is proposed, along with an analysis of the reactivity of a triiron complex in which di(thiomethyl)amine--the chelating group naturally occurring in [FeFe]-hydrogenases--substitutes the benzyl-containing dithiolate ligand. PMID:23374093

  2. Phase-field Model for Interstitial Loop Growth Kinetics and Thermodynamic and Kinetic Models of Irradiated Fe-Cr Alloys

    SciTech Connect

    Li, Yulan; Hu, Shenyang Y.; Sun, Xin; Khaleel, Mohammad A.

    2011-06-15

    strength of interstitial loop for interstitials. In part II, we present a generic phase field model and discuss the thermodynamic and kinetic properties in phase-field models including the reaction kinetics of radiation defects and local free energy of irradiated materials. In particular, a two-sublattice thermodynamic model is suggested to describe the local free energy of alloys with irradiated defects. Fe-Cr alloy is taken as an example to explain the required thermodynamic and kinetic properties for quantitative phase-field modeling. Finally the great challenges in phase-field modeling will be discussed.

  3. Multi-view and 3D deformable part models.

    PubMed

    Pepik, Bojan; Stark, Michael; Gehler, Peter; Schiele, Bernt

    2015-11-01

    As objects are inherently 3D, they have been modeled in 3D in the early days of computer vision. Due to the ambiguities arising from mapping 2D features to 3D models, 3D object representations have been neglected and 2D feature-based models are the predominant paradigm in object detection nowadays. While such models have achieved outstanding bounding box detection performance, they come with limited expressiveness, as they are clearly limited in their capability of reasoning about 3D shape or viewpoints. In this work, we bring the worlds of 3D and 2D object representations closer, by building an object detector which leverages the expressive power of 3D object representations while at the same time can be robustly matched to image evidence. To that end, we gradually extend the successful deformable part model [1] to include viewpoint information and part-level 3D geometry information, resulting in several different models with different level of expressiveness. We end up with a 3D object model, consisting of multiple object parts represented in 3D and a continuous appearance model. We experimentally verify that our models, while providing richer object hypotheses than the 2D object models, provide consistently better joint object localization and viewpoint estimation than the state-of-the-art multi-view and 3D object detectors on various benchmarks (KITTI [2] , 3D object classes [3] , Pascal3D+ [4] , Pascal VOC 2007 [5] , EPFL multi-view cars[6] ). PMID:26440264

  4. Microstructure Modeling of a Ni-Fe-Based Superalloy During the Rotary Forging Process

    NASA Astrophysics Data System (ADS)

    Loyda, A.; Hernández-Muñoz, G. M.; Reyes, L. A.; Zambrano-Robledo, P.

    2016-06-01

    The microstructure evolution of Ni-Fe superalloys has a great influence on the mechanical behavior during service conditions. The rotary forging process offers an alternative to conventional bulk forming processes where the parts can be rotary forged with a fraction of the force commonly needed by conventional forging techniques. In this investigation, a numerical modeling of microstructure evolution for design and optimization of the hot forging operations has been used to manufacture a heat-resistant nickel-based superalloy. An Avrami model was implemented into finite element commercial platform DEFORM 3D to evaluate the average grain size and recrystallization during the rotary forging process. The simulations were carried out considering three initial temperatures, 980, 1000, and 1050 °C, to obtain the microstructure behavior after rotary forging. The final average grain size of one case was validated by comparing with results of previous experimental work of disk forging operation. This investigation was aimed to explore the influence of the rotary forging process on microstructure evolution in order to obtain a homogenous and refined grain size in the final component.

  5. Modeling of aircraft unsteady aerodynamic characteristics. Part 1: Postulated models

    NASA Technical Reports Server (NTRS)

    Klein, Vladislav; Noderer, Keith D.

    1994-01-01

    A short theoretical study of aircraft aerodynamic model equations with unsteady effects is presented. The aerodynamic forces and moments are expressed in terms of indicial functions or internal state variables. The first representation leads to aircraft integro-differential equations of motion; the second preserves the state-space form of the model equations. The formulations of unsteady aerodynamics is applied in two examples. The first example deals with a one-degree-of-freedom harmonic motion about one of the aircraft body axes. In the second example, the equations for longitudinal short-period motion are developed. In these examples, only linear aerodynamic terms are considered. The indicial functions are postulated as simple exponentials and the internal state variables are governed by linear, time-invariant, first-order differential equations. It is shown that both approaches to the modeling of unsteady aerodynamics lead to identical models.

  6. Modeling of the magnetic free energy of self-diffusion in bcc Fe

    NASA Astrophysics Data System (ADS)

    Sandberg, N.; Chang, Z.; Messina, L.; Olsson, P.; Korzhavyi, P.

    2015-11-01

    A first-principles based approach to calculating self-diffusion rates in bcc Fe is discussed with particular focus on the magnetic free energy associated with diffusion activation. First, the enthalpies and entropies of vacancy formation and migration in ferromagnetic bcc Fe are calculated from standard density functional theory methods in combination with transition state theory. Next, the shift in diffusion activation energy when going from the ferromagnetic to the paramagnetic state is estimated by averaging over random spin states. Classical and quantum mechanical Monte Carlo simulations within the Heisenberg model are used to study the effect of spin disordering on the vacancy formation and migration free energy. Finally, a quasiempirical model of the magnetic contribution to the diffusion activation free energy is applied in order to connect the current first-principles results to experimental data. The importance of the zero-point magnon energy in modeling of diffusion in bcc Fe is stressed.

  7. Synthetic and structural studies on L-cysteinyl group-containing diiron/triiron azadithiolates as active site models of [FeFe]-hydrogenases.

    PubMed

    Song, Li-Cheng; Yan, Jing; Li, Yu-Long; Wang, De-Fu; Hu, Qing-Mei

    2009-12-01

    Five new L-cysteinyl group-containing diiron/triiron azadithiolate complexes (3-6, 10), which could be regarded as the active site models of [FeFe]-hydrogenases, have been successfully synthesized. Treatment of L-cysteinyl sodium mercaptide CytSNa (1, Cyt = CH(2)CH(CO(2)Et)NH(CO(2)Bu-t) with complex [(mu-SCH(2))(2)NCH(2)CH(2)Br]Fe(2)(CO)(6) (2) in THF at room temperature resulted in formation of model complex [(mu-SCH(2))(2)NCH(2)CH(2)SCyt]Fe(2)(CO)(6) (3). Further treatment of 3 with decarbonylating agent Me(3)NO in MeCN at room temperature afforded model complex [(mu-SCH(2))(2)NCH(2)CH(2)SCyt]Fe(2)(CO)(5) (4). Similarly, treatment of 3 with an equimolar mixture of Me(3)NO and Ph(3)P gave model complex [(mu-SCH(2))(2)NCH(2)CH(2)SCyt]Fe(2)(CO)(5)(Ph(3)P) (5) and further treatment of 5 with Me(3)NO produced model complex [(mu-SCH(2))(2)NCH(2)CH(2)SCyt]Fe(2)(CO)(4)(Ph(3)P) (6). More interestingly, model complex [(mu-SCH(2))(2)NCH(CO(2)Et)CH(2)SFe(CO)(2)Cp]Fe(2)(CO)(5) (10) could be synthesized by a "one pot" reaction of the in situ prepared (mu-HS)(2)Fe(2)(CO)(6) (9) with 37% aqueous formaldehyde followed by treatment with the N-deprotected L-cysteinyl iron mercaptide Cp(CO)(2)FeSCH(2)CH(CO(2)Et)NH(2) (8). Complex 8 is new, which was prepared by treatment of complex Cp(CO)(2)FeSCyt (7) with CF(3)CO(2)H followed by 25% aqueous NH(3). All the new complexes 3-6, 8, and 10 were characterized by elemental analysis and various spectroscopic techniques, whereas complexes 5 and 10 were further characterized by X-ray crystallography. PMID:19860376

  8. Fe doped TiO2-graphene nanostructures: synthesis, DFT modeling and photocatalysis.

    PubMed

    Farhangi, Nasrin; Ayissi, Serge; Charpentier, Paul A

    2014-08-01

    In this work, Fe-doped TiO(2) nanoparticles ranging from a 0.2 to 1 weight % were grown from the surface of graphene sheet templates containing -COOH functionalities using sol-gel chemistry in a green solvent, a mixture of water/ethanol. The assemblies were characterized by a variety of analytical techniques, with the coordination mechanism examined theoretically using the density functional theory (DFT). Scanning electron microscopy and transmission electron microscopy images showed excellent decoration of the Fe-doped TiO(2) nanoparticles on the surface of the graphene sheets >5 nm in diameter. The surface area and optical properties of the Fe-doped photocatalysts were measured by BET, UV and PL spectrometry and compared to non-graphene and pure TiO(2) analogs, showing a plateau at 0.6% Fe. Interactions between graphene and Fe-doped anatase TiO(2) were also studied theoretically using the Vienna ab initio Simulation Package based on DFT. Our first-principles theoretical investigations validated the experimental findings, showing the strength in the physical and chemical adsorption between the graphene and Fe-doped TiO(2). The resulting assemblies were tested for photodegradation under visible light using 17β-estradiol (E2) as a model compound, with all investigated catalysts showing significant enhancements in photocatalytic activity in the degradation of E2. PMID:25002220

  9. Fe doped TiO2-graphene nanostructures: synthesis, DFT modeling and photocatalysis

    NASA Astrophysics Data System (ADS)

    Farhangi, Nasrin; Ayissi, Serge; Charpentier, Paul A.

    2014-08-01

    In this work, Fe-doped TiO2 nanoparticles ranging from a 0.2 to 1 weight % were grown from the surface of graphene sheet templates containing -COOH functionalities using sol-gel chemistry in a green solvent, a mixture of water/ethanol. The assemblies were characterized by a variety of analytical techniques, with the coordination mechanism examined theoretically using the density functional theory (DFT). Scanning electron microscopy and transmission electron microscopy images showed excellent decoration of the Fe-doped TiO2 nanoparticles on the surface of the graphene sheets >5 nm in diameter. The surface area and optical properties of the Fe-doped photocatalysts were measured by BET, UV and PL spectrometry and compared to non-graphene and pure TiO2 analogs, showing a plateau at 0.6% Fe. Interactions between graphene and Fe-doped anatase TiO2 were also studied theoretically using the Vienna ab initio Simulation Package based on DFT. Our first-principles theoretical investigations validated the experimental findings, showing the strength in the physical and chemical adsorption between the graphene and Fe-doped TiO2. The resulting assemblies were tested for photodegradation under visible light using 17β-estradiol (E2) as a model compound, with all investigated catalysts showing significant enhancements in photocatalytic activity in the degradation of E2.

  10. Experimental Validation of Modeled Fe Opacities at Conditions Approaching the Base of the Solar Convection Zone

    NASA Astrophysics Data System (ADS)

    Nagayama, Taisuke

    2013-10-01

    Knowledge of the Sun is a foundation for other stars. However, after the solar abundance revision in 2005, standard solar models disagree with helioseismic measurements particularly at the solar convection zone base (CZB, r ~ 0 . 7 ×RSun) [Basu, et al., Physics Reports 457, 217 (2008)]. One possible explanation is an underestimate in the Fe opacity at the CZB [Bailey et al., Phys. Plasmas 16, 058101 (2009)]. Modeled opacities are important physics inputs for plasma simulations (e.g. standard solar models). However, modeled opacities are not experimentally validated at high temperatures because of three challenging criteria required for reliable opacity measurements: 1) smooth and strong backlighter, 2) plasma condition uniformity, and 3) simultaneous measurements of plasma condition and transmission. Fe opacity experiments are performed at the Sandia National Laboratories (SNL) Z-machine aiming at conditions close to those at the CZB (i.e. Te = 190 eV, ne = 1 ×1023 cm-3). To verify the quality of the experiments, it is critical to investigate how well the three requirements are satisfied. The smooth and strong backlighter is provided by the SNL Z-pinch dynamic hohlraum. Fe plasma condition is measured by mixing Mg into the Fe sample and employing Mg K-shell line transmission spectroscopy. Also, an experiment is designed and performed to measure the level of non-uniformity in the Fe plasma by mixing Al and Mg dopants on the opposite side of the Fe sample and analyzing their spectra. We will present quantitative results on these investigations as well as the comparison of the measured opacity to modeled opacities. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000.

  11. Deformable part models for object detection in medical images

    PubMed Central

    2014-01-01

    Background Object detection in 3-D medical images is often necessary for constraining a segmentation or registration task. It may be a task in its own right as well, when instances of a structure, e.g. the lymph nodes, are searched. Problems from occlusion, illumination and projection do not arise, making the problem simpler than object detection in photographies. However, objects of interest are often not well contrasted against the background. Influence from noise and other artifacts is much stronger and shape and appearance may vary substantially within a class. Methods Deformable models capture the characteristic shape of an anatomic object and use constrained deformation for hypothesing object boundaries in image regions of low or non-existing contrast. Learning these constraints requires a large sample data base. We show that training may be replaced by readily available user knowledge defining a prototypical deformable part model. If structures have a strong part-relationship, or if they may be found based on spatially related guiding structures, or if the deformation is rather restricted, the supporting data information suffices for solving the detection task. We use a finite element model to represent anatomic variation by elastic deformation. Complex shape variation may be represented by a hierarchical model with simpler part variation. The hierarchy may be represented explicitly as a hierarchy of sub-shapes, or implicitly by a single integrated model. Data support and model deformation of the complete model can be represented by an energy term, serving as quality-of-fit function for object detection. Results The model was applied to detection and segmentation tasks in various medical applications in 2- and 3-D scenes. It has been shown that model fitting and object detection can be carried out efficiently by a combination of a local and global search strategy using models that are parameterized for the different tasks. Conclusions A part-based elastic

  12. 17 CFR Appendix A to Part 160 - Model Privacy Form

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 2 2014-04-01 2014-04-01 false Model Privacy Form A Appendix... Appendix A to Part 160—Model Privacy Form A. The Model Privacy Form ER28DE12.003 ER28DE12.004 ER28DE12.005 ER28DE12.006 ER28DE12.007 ER28DE12.008 ER28DE12.009 B. General Instructions 1. How the Model Privacy...

  13. An internally consistent model for the thermodynamic properties of Fe-Mg-titanomagnetite-aluminate spinels

    NASA Astrophysics Data System (ADS)

    Sack, Richard O.; Ghiorso, Mark S.

    1991-02-01

    A model is developed for the thermodynamic properties of Fe2+-Mg2+-aluminate-titanate-ferrite spinels of space group Fd3m. The model incorporates an expression for the configurational entropy of mixing which accounts for long-range order over tetrahedral and octahedral sites. Short-range order or departures from cubic symmetry are not considered. The non-configurational Gibbs energy is formulated as a second degree Taylor expansion in six linearly independent composition and ordering variables. The model parameters are calibrated to reproduce miscibility gap constraints, order-disorder phenomena in MgAl2O4 and MgFe2O4, and Fe2+-Mg2+ partitioning data between olivine and: (1) aluminate spinels; (2) ferrite spinels; (3) titanate spinels; (4) mixed aluminate-ferrite spinels. This calibration is achieved without invoking non-configurational excess entropies of mixing. The model predicts that the ordering state of FeAl2O4 is more normal than that of MgAl2O4. It also successfully accounts for heat of solution measurements and activity-composition relations in the constituent binaries. Phase equilibrium constraints require that the structure of Fe3O4 is more inverse than random at all temperatures and that Mg2+ has a strong tetrahedral site preference with respect to that of Fe2+. The analysis suggests that in the titanates short range order on octahedral sites may be significant at temperatures as high as 1300° C. Constraints developed from calibrating the thermodynamic properties of Fe2+-Mg2+-aluminatetitanate-ferrite spinel solid solutions permit extension of the database of Berman (1988) to include estimates of the end-member properties of hercynite (FeAl2O4), ulvöspinel (Fe2TiO4), MgFe2O4 and cubic Mg2TiO4. In constructing these estimates, provision is made for low-temperature magnetic entropy contributions and the energetic consequences of disordering the aluminates and the ferrites. These estimates are consistent with all of the available low

  14. Ab Initio Modeling of Fe(II) Adsorption and Interfacial Electron Transfer at Goethite (α-FeOOH) Surfaces

    SciTech Connect

    Alexandrov, Vitali Y.; Rosso, Kevin M.

    2015-01-01

    Goethite (α-FeOOH) surfaces represent one of the most ubiquitous redox-active interfaces in the environment, playing an important role in biogeochemical metal cycling and contaminant residence in the subsurface. Fe(II)-catalyzed recrystallization of goethite is a fundamental process in this context, but the proposed Fe(II)aq-Fe(III)goethite electron and iron atom exchange mechanism of recrystallization remains poorly understood at the atomic level. We examine the adsorption of aqueous Fe(II) and subsequent interfacial electron transfer (ET) between adsorbed Fe(II) and structural Fe(III) at the (110) and (021) goethite surfaces using density functional theory calculations including Hubbard U corrections (DFT+U) aided by ab initio molecular dynamics simulations. We investigate various surface sites for the adsorption of Fe2+(H2O)6 in different coordination environments. Calculated energies for adsorbed complexes at both surfaces favor monodentate complexes with reduced 4- and 5-fold coordination over higher-dentate structures and 6- fold coordination. The hydrolysis of H2O ligands is observed for some pre-ET adsorbed Fe(II) configurations. ET from the adsorbed Fe(II) into the goethite lattice is calculated to be energetically uphill always, but simultaneous proton transfer from H2O ligands of the adsorbed complexes to the surface oxygen species stabilizes post-ET states. We find that surface defects such as oxygen vacancies near the adsorption site also can stabilize post-ET states, enabling the Fe(II)aq-Fe(III)goethite interfacial electron transfer reaction implied from experiments to proceed.

  15. Solubility of Fe(III) and Al in AMD by modelling and experimtn

    SciTech Connect

    Mitchell, K.G.; Wildeman, T.R.

    1995-12-01

    Studies of Fe(III) and Al species in acid mine drainage (AMD) alone and in contact with limestone were conducted by MINTEQA2 and by experiments. Using Fe(OH){sub 3} as the primary species and the standard values for MINTEQ, Fe(III) precipitates at pH 2.90 when the concentration is 453 mg/L. Al precipitates at a pH of 4.00 when the concentration is 108 mg/L. Experiments found that over 90 % of Fe(III) and 45 % of Al were precipitated at these pH`s. Experimental verification of Fe(III) concentrations at pH`s from 2.90 to 4.0 found that modelling agreed with experiment when ferrihydrite is the primary solid and the log Ksp is -38.9. For Al, gibbsite would be the primary solid and log Ksp is -34.1. For AMD in contact with CaCO{sub 3} when CO{sub 2} is conserved, final alkalinity is higher when mineral acidity is higher even though pH of the final solution is lower. This modelling result was confirmed by experiment. Higher mineral acidity causes generation of more CO{sub 2} that reacts with CaCO{sub 3} to generate more dissolved HCO{sub 3-}.

  16. Reactive Transport Modeling of Microbe-mediated Fe (II) Oxidation for Enhanced Oil Recovery

    NASA Astrophysics Data System (ADS)

    Surasani, V.; Li, L.

    2011-12-01

    Microbially Enhanced Oil Recovery (MEOR) aims to improve the recovery of entrapped heavy oil in depleted reservoirs using microbe-based technology. Reservoir ecosystems often contain diverse microbial communities those can interact with subsurface fluids and minerals through a network of nutrients and energy fluxes. Microbe-mediated reactions products include gases, biosurfactants, biopolymers those can alter the properties of oil and interfacial interactions between oil, brine, and rocks. In addition, the produced biomass and mineral precipitates can change the reservoir permeability profile and increase sweeping efficiency. Under subsurface conditions, the injection of nitrate and Fe (II) as the electron acceptor and donor allows bacteria to grow. The reaction products include minerals such as Fe(OH)3 and nitrogen containing gases. These reaction products can have large impact on oil and reservoir properties and can enhance the recovery of trapped oil. This work aims to understand the Fe(II) oxidation by nitrate under conditions relevant to MEOR. Reactive transport modeling is used to simulate the fluid flow, transport, and reactions involved in this process. Here we developed a complex reactive network for microbial mediated nitrate-dependent Fe (II) oxidation that involves both thermodynamic controlled aqueous reactions and kinetic controlled Fe (II) mineral reaction. Reactive transport modeling is used to understand and quantify the coupling between flow, transport, and reaction processes. Our results identify key parameter controls those are important for the alteration of permeability profile under field conditions.

  17. Accurate wavelength measurements and modeling of FeXV to FeXIX spectra recorded in high density plasmas between 13.5 to 17 A.

    SciTech Connect

    May, M; Beiersdorfer, P; Dunn, J; Jordan, N; Osterheld, A; Faenov, A; Pikuz, T; Skobelev, I; Fora, F; Bollanti, S; Lazzaro, P D; Murra, D; Reale, A; Reale, L; Tomassetti, G; Ritucci, A; Francucci, M; Martellucci, S; Petrocelli, G

    2004-09-28

    Iron spectra have been recorded from plasmas created at three different laser plasma facilities, the Tor Vergata University laser in Rome (Italy), the Hercules laser at ENEA in Frascati (Italy), and the Compact Multipulse Terawatt (COMET) laser at LLNL in California (USA). The measurements provide a means of identifying dielectronic satellite lines from FeXVI and FeXV in the vicinity of the strong 2p {yields} 3d transitions of FeXVII. About 80 {Delta}n {ge} 1 lines of FeXV (Mg-like) to FeXIX (O-like) were recorded between 13.8 to 17.1 {angstrom} with a high spectral resolution ({lambda}/{Delta}{lambda} {approx} 4000), about thirty of these lines are from FeXVI and FeXV. The laser produced plasmas had electron temperatures between 100 to 500 eV and electron densities between 10{sup 20} to 10{sup 22} cm{sup -3}. The Hebrew University Lawrence Livermore Atomic Code (HULLAC) was used to calculate the atomic structure and atomic rates for FeXV to FeXIX. HULLAC was used to calculate synthetic line intensities at T{sub e} = 200 eV and n{sub e} = 10{sup 21}cm{sup -3} for three different conditions to illustrate the role of opacity: optically thin plasmas with no excitation-autoionization/dielectronic recombination (EA/DR) contributions to the line intensities, optically thin plasmas that included EA/DR contributions to the line intensities, and optically thick plasmas (optical depth {approx} 200 {micro}m) that included EA/DR contributions to the line intensities. The optically thick simulation best reproduced the recorded spectrum from the Hercules laser. However some discrepancies between the modeling and the recorded spectra remain.

  18. Micrometer-size Nd-Fe-B dots as model systems for the study of intergranular phase engineering in Nd-Fe-B permanent magnets

    NASA Astrophysics Data System (ADS)

    Le Roy, Damien; Akdogan, Ozan; Ciuta, Georgeta; Dempsey, Nora; Givord, Dominique

    2014-05-01

    Nd-Fe-B micrometer-size dots were prepared by optical lithography and sputtering. It is proposed to use such structures as model systems to study intergranular phase engineering in Nd-Fe-B permanent magnets. The influence of Ta, Nd, Dy, and Gd coatings on the magnetization reversal of such Nd-Fe-B dot arrays are compared, after different heat treatments. A very thin layer of Dy (tNdFeB/tDy = 120) was found to lead to a significant increase of the coercive field, up to 80% for a total equivalent Dy content of less than 5 at. % of all the Nd. A coercivity increase of up to 20% was found with Gd coating which is attributed to the so-called superferrimagnetic coupling phenomenon. Nd and Ta coating are neutral or detrimental to the magnetic hardness.

  19. Precursors to [FeFe]-Hydrogenase Models: Syntheses of Fe2(SR)2(CO)6 from CO-Free Iron Sources

    PubMed Central

    Chen, Jinzhu; Boyke, Christine; Rauchfuss, Thomas B.; Volkers, Phillip I.; Whaley, C. Matthew; Wilson, Scott R.; Yao, Haijun

    2008-01-01

    This report describes routes to iron dithiolato carbonyls that do not require preformed iron carbonyls. The reaction of FeCl2, Zn, and Q2S2CnH2n (Q+ = Na+, Et3NH+) under an atmosphere of CO affords Fe2(S2CnH2n)(CO)6 (n = 2, 3) in yields >70%. The method was employed to prepare Fe2(S2C2H4)(13CO)6. Treatment of these carbonylated mixtures with tertiary phosphines gave the ferrous species Fe3(S2C3H6)3(CO)4(PR3)2, for R = Et, Bu, and Ph. Like the related complex Fe3(SPh)6(CO)6, these compounds consist of a linear arrangement of three conjoined face-shared octahedral centers. Omitting the phosphine but with an excess of dithiolate, we obtained the related mixed-valence triiron species [Fe3(S2CnH2n)4(CO)4]−. The highly reducing all-ferrous species [Fe3(S2CnH2n)4(CO)4]2− is implicated as an intermediate in this transformation. Reactive forms of iron, prepared by the method of Rieke, also combined with dithiols under a CO atmosphere to give Fe2(S2CnH2n)(CO)6 in modest yields under mild conditions. Studies on the order of addition indicate that ferrous thiolates are formed prior to the onset of carbonylation. Crystallographic characterization demonstrated that the complexes Fe3(S2C3H6)3(CO)4(PEt3)2 and PBnPh3[Fe3(S2C3H6)4(CO)4] feature high spin ferrous and low spin ferric as the central metal, respectively. PMID:18610969

  20. Precursors to [FeFe]-hydrogenase models: syntheses of Fe2(SR)2(CO)6 from CO-free iron sources.

    PubMed

    Volkers, Phillip I; Boyke, Christine A; Chen, Jinzhu; Rauchfuss, Thomas B; Whaley, C Matthew; Wilson, Scott R; Yao, Haijun

    2008-08-01

    This report describes routes to iron dithiolato carbonyls that do not require preformed iron carbonyls. The reaction of FeCl 2, Zn, and Q 2S 2C n H 2 n (Q (+) = Na (+), Et 3NH (+)) under an atmosphere of CO affords Fe 2(S 2C n H 2 n )(CO) 6 ( n = 2, 3) in yields >70%. The method was employed to prepare Fe 2(S 2C 2H 4)( (13)CO) 6. Treatment of these carbonylated mixtures with tertiary phosphines, instead of Zn, gave the ferrous species Fe 3(S 2C 3H 6) 3(CO) 4(PR 3) 2, for R = Et, Bu, and Ph. Like the related complex Fe 3(SPh) 6(CO) 6, these compounds consist of a linear arrangement of three conjoined face-shared octahedral centers. Omitting the phosphine but with an excess of dithiolate, we obtained the related mixed-valence triiron species [Fe 3(S 2C n H 2 n ) 4(CO) 4] (-). The highly reducing all-ferrous species [Fe 3(S 2C n H 2 n ) 4(CO) 4] (2-) is implicated as an intermediate in this transformation. Reactive forms of iron, prepared by the method of Rieke, also combined with dithiols under a CO atmosphere to give Fe 2(S 2C n H 2 n )(CO) 6 in modest yields under mild conditions. Studies on the order of addition indicate that ferrous thiolates are formed prior to the onset of carbonylation. Crystallographic characterization demonstrated that the complexes Fe 3(S 2C 3H 6) 3(CO) 4(PEt 3) 2 and PBnPh 3[Fe 3(S 2C 3H 6) 4(CO) 4] feature high-spin ferrous and low-spin ferric as the central metal, respectively. PMID:18610969

  1. Solubility of Fe(III) Al in AMD by modelling and experiment

    SciTech Connect

    Mitchell, K.G.; Wildeman, T.R.

    1996-12-31

    Studies of Fe(III) and Al species in acid mine drainage (AMD) alone and in contact with limestone were conducted by MINTEQA2 modelling and by experiments. The objectives of these studies were to: (1) determine at what pH Fe(III) and Al would be in solution in AMD such that the water would be harmful to an anoxic limestone drain (ALD), and (2) evaluate the theoretical limits to the amount of alkalinity that could be generated by an ALD. Using Fe(OH){sub 3} as the primary species and the standard values for MINTEQA2, Fe(III) precipitates at pH 2.90 when the concentration is over 453 mg/L. Al precipitates at a pH of 4.00 when the concentration is over 108 mg/L. Experiments found that over 90 % of Fe(III) and 45% of Al were precipitated at these pH`s. Experimental verification of Fe(III) concentrations of pH`s from 2.90 to 4.0 found that modelling agreed with experiment when ferrihydrite is the primary solid and the log Ksp (solubility product) is -38.9. For Al, gibbsite would be the primary solid and log Ksp is -34.1. For AMD in contact with CaCO{sub 3} when CO{sub 2} is conserved, final alkalinity is higher when mineral acidity is higher even though pH of the final solution is lower. This modelling result was confirmed by experiment. Higher mineral acidity causes generation of more CO{sub 2} that reacts with CaCO{sub 3} to generate more dissolved HCO{sub -3}.

  2. 52. KEWANEE BOILER, MODEL FE561L. INSTALLED C. 1960 TO SUPPLEMENT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    52. KEWANEE BOILER, MODEL FE-561-L. INSTALLED C. 1960 TO SUPPLEMENT THE HARTLEY BOILERS (SEE PREVIOUS PHOTOS 50 AND 51). LOCATED IN BOILER ROOM ADDITION WEST OF MAIN BOILER ROOM. - Prattville Manufacturing Company, Number One, 242 South Court Street, Prattville, Autauga County, AL

  3. CONSTRAINING TYPE Ia SUPERNOVA MODELS: SN 2011fe AS A TEST CASE

    SciTech Connect

    Roepke, F. K.; Seitenzahl, I. R.; Kromer, M.; Taubenberger, S.; Ciaraldi-Schoolmann, F.; Hillebrandt, W.; Benitez-Herrera, S.; Pakmor, R.; Sim, S. A.; Aldering, G.; Childress, M.; Fakhouri, H. K.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Baltay, C.; Buton, C.; Chotard, N.; Copin, Y. [Universite de Lyon, F-69622, Lyon; Universite de Lyon 1, Villeurbanne; CNRS and others

    2012-05-01

    The nearby supernova SN 2011fe can be observed in unprecedented detail. Therefore, it is an important test case for Type Ia supernova (SN Ia) models, which may bring us closer to understanding the physical nature of these objects. Here, we explore how available and expected future observations of SN 2011fe can be used to constrain SN Ia explosion scenarios. We base our discussion on three-dimensional simulations of a delayed detonation in a Chandrasekhar-mass white dwarf and of a violent merger of two white dwarfs (WDs)-realizations of explosion models appropriate for two of the most widely discussed progenitor channels that may give rise to SNe Ia. Although both models have their shortcomings in reproducing details of the early and near-maximum spectra of SN 2011fe obtained by the Nearby Supernova Factory (SNfactory), the overall match with the observations is reasonable. The level of agreement is slightly better for the merger, in particular around maximum, but a clear preference for one model over the other is still not justified. Observations at late epochs, however, hold promise for discriminating the explosion scenarios in a straightforward way, as a nucleosynthesis effect leads to differences in the {sup 55}Co production. SN 2011fe is close enough to be followed sufficiently long to study this effect.

  4. Lidar Observations and Numerical Modeling Studies of Thermospheric Metal Layers and Solar Effects on Mesospheric Fe Layers

    NASA Astrophysics Data System (ADS)

    Yu, Zhibin

    By blocking extreme hazards from space and regulating radio wave propagation, the space-atmosphere interaction region (SAIR) -- our window to open space -- is essential for life on Earth and modern society. However, the physical and chemical processes governing the SAIR are not sufficiently understood due to the woefully incomplete measurements of neutral properties in this region, especially between 100 and 200 km altitude. Thermospheric Fe layers extending from ~70 to 170 km discovered by the Fe Boltzmann lidar at McMurdo, Antarctica have opened a new door to observing the neutral thermosphere and mesosphere. This thesis is aimed at revealing such new discoveries, and advancing our understanding of the thermospheric Fe layer formation, through analyzing the lidar data collected by the author in Antarctic winter and developing the first thermospheric Fe/Fe+ model. A one-dimensional high-latitude Fe/Fe+ model based on physical and chemical first principles has been developed to quantitatively explore the source, formation and evolution of thermospheric Fe layers. We demonstrate that the observed Fe layers are produced by neutralization of converged Fe+, mainly through the direct electron-Fe+ recombination. We find that the polar electric field is capable of uplifting Fe+ ions from the main deposition region into the thermosphere, supplying the source of neutral Fe. Both gravity-wave-induced wind shears and the polar electric field can converge Fe+ layers. Vertical wind plays a key role in transporting Fe to form the observed wave structures, but horizontal divergence can largely offset the vertical convergence effects. These theoretical studies lay the foundation for exploring the thermosphere by resonance lidars. The diurnal variations of Fe layers in the mesopause region are characterized with our lidar observations at McMurdo. A new finding is the solar effect on the Fe layer bottomside --- daytime downward extension and nighttime upward contraction. We explain

  5. Controlled Nonlinear Stochastic Delay Equations: Part I: Modeling and Approximations

    SciTech Connect

    Kushner, Harold J.

    2012-08-15

    This two-part paper deals with 'foundational' issues that have not been previously considered in the modeling and numerical optimization of nonlinear stochastic delay systems. There are new classes of models, such as those with nonlinear functions of several controls (such as products), each with is own delay, controlled random Poisson measure driving terms, admissions control with delayed retrials, and others. There are two basic and interconnected themes for these models. The first, dealt with in this part, concerns the definition of admissible control. The classical definition of an admissible control as a nonanticipative relaxed control is inadequate for these models and needs to be extended. This is needed for the convergence proofs of numerical approximations for optimal controls as well as to have a well-defined model. It is shown that the new classes of admissible controls do not enlarge the range of the value functions, is closed (together with the associated paths) under weak convergence, and is approximatable by ordinary controls. The second theme, dealt with in Part II, concerns transportation equation representations, and their role in the development of numerical algorithms with much reduced memory and computational requirements.

  6. GSTARS computer models and their applications, Part II: Applications

    USGS Publications Warehouse

    Simoes, F.J.M.; Yang, C.T.

    2008-01-01

    In part 1 of this two-paper series, a brief summary of the basic concepts and theories used in developing the Generalized Stream Tube model for Alluvial River Simulation (GSTARS) computer models was presented. Part 2 provides examples that illustrate some of the capabilities of the GSTARS models and how they can be applied to solve a wide range of river and reservoir sedimentation problems. Laboratory and field case studies are used and the examples show representative applications of the earlier and of the more recent versions of GSTARS. Some of the more recent capabilities implemented in GSTARS3, one of the latest versions of the series, are also discussed here with more detail. ?? 2008 International Research and Training Centre on Erosion and Sedimentation and the World Association for Sedimentation and Erosion Research.

  7. A Material Model for FE-Simulation of UD Composites

    NASA Astrophysics Data System (ADS)

    Fischer, Sebastian

    2016-04-01

    Composite materials are being increasingly used for industrial applications. CFRP is particularly suitable for lightweight construction due to its high specific stiffness and strength properties. Simulation methods are needed during the development process in order to reduce the effort for prototypes and testing. This is particularly important for CFRP, as the material is costly. For accurate simulations, a realistic material model is needed. In this paper, a material model for the simulation of UD-composites including non-linear material behaviour and damage is developed and implemented in Abaqus. The material model is validated by comparison with test results on a range of test specimens.

  8. Irradiation-enhanced α' precipitation in model FeCrAl alloys

    DOE PAGESBeta

    Edmondson, Philip D.; Briggs, Samuel A.; Yamamoto, Yukinori; Howard, Richard H.; Sridharan, Kumar; Terrani, Kurt A.; Field, Kevin G.

    2016-02-17

    Model FeCrAl alloys with varying compositions (Fe(10–18)Cr(10–6)Al at.%) have been neutron irradiated at ~ 320 to damage levels of ~ 7 displacements per atom (dpa) to investigate the compositional influence on the formation of irradiation-induced Cr-rich α' precipitates using atom probe tomography. In all alloys, significant number densities of these precipitates were observed. Cluster compositions were investigated and it was found that the average cluster Cr content ranged between 51.1 and 62.5 at.% dependent on initial compositions. This is significantly lower than the Cr-content of α' in binary FeCr alloys. As a result, significant partitioning of the Al from themore » α' precipitates was also observed.« less

  9. Modeling of Ultrafast Heat- and Field-Assisted Magnetization Dynamics in FePt

    NASA Astrophysics Data System (ADS)

    Nieves, P.; Chubykalo-Fesenko, O.

    2016-01-01

    The switching of magnetization by ultrafast lasers alone in FePt could open a technological perspective for magnetic recording technology. Recent experimental results [D. Lambert et al., Science 345, 1337 (2014)] indicate a dynamical magnetization response in FePt under circularly polarized laser pulses. Using high-temperature micromagnetic modeling, based on the stochastic Landau-Lifshitz-Bloch equation, we investigate the possibility of magnetization switching in FePt under the action of an ultrafast heat pulse assisted by either a constant or optomagnetic field. We evaluate the necessary magnitude and duration of the inverse Faraday field to produce a reliable switching. Our results also reproduce experimentally observed magnetization patterns originated from the nonhomogeneous temperature distribution.

  10. Thermo-mechanical modelling of aluminium cast parts during solution treatment

    NASA Astrophysics Data System (ADS)

    Bellini, A.; Hattel, J. H.; Thorborg, J.

    2006-06-01

    The increasing interest of the automotive industry in reducing the weight of cars has resulted in increasing replacement of steel with aluminium parts as well as in an optimization of the design of the components, through structural analysis by FE-codes. The design and manufacturing of these components are important for the lifetime and reliability of the final parts. It is common practice to do load analyses in order to evaluate component lifetime and to do design optimization. However, in order to improve these structural analyses it is important to include the full load history of the material including the influence of the casting process and the subsequent solution treatment phase, quenching and artificial ageing. These manufacturing stages can have a high influence on the deformation and development of residual stresses which are important as initial conditions for subsequent load analysis during service. This paper presents a 3D numerical procedure capable of modelling the development of deformations and stresses from the full thermal history starting from mould filling through solidification to cooling and subsequent reheating for solution treatment, quenching and artificial ageing. However, in the present work the focus is on the modelling of the solution treatment only. The mechanical material model is described by a unified creep model to include rate effects and inelastic behaviour. An industrial component is used as an example to present the influence of creep at high temperature and calculated results with regard to deformations are compared with measurements.

  11. Slot spiral antenna modeling using hybrid/mixed FE-BI technique

    NASA Technical Reports Server (NTRS)

    Gong, Jian; Volakis, John L.

    1995-01-01

    This report is concerned with the numerical simulation of the printed slot spiral antenna (SSA) using the finite element - boundary integral (FE-BI) analysis. It has been reported that the FE-BI technique is suited for modeling microstrip patch antennas of any shape, printed on layered planar structure or cylindrical platform and fed with a coaxial cable or a microstripline network underneath the radiating elements. However, direct application of the hybrid FE-BI technique to thin slot spirals requires excessive sampling rates to accurately simulate the geometry. To alleviate the meshing/modeling difficulties encountered with cavity-backed slot antennas, we describe a mixed finite element-boundary integral formulation. As in the past, the boundary integral is used to describe the radiation of the slot above the cavity. However the cavity is now modeled using a suitable mix of edge and node elements. The latter are used only at the aperture of the thin slot so that the nodes follow the center line of the slot. In this manner, regular size elements can be used regardless of the slot's width and any meshing restrictions are substantially relaxed. The proposed mixed element FE-BI formulation introduces three different computational regions and as expected this complicates the generation of the discrete system.

  12. Integrating O/S models during conceptual design, part 3

    NASA Technical Reports Server (NTRS)

    Ebeling, Charles E.

    1994-01-01

    Space vehicles, such as the Space Shuttle, require intensive ground support prior to, during, and after each mission. Maintenance is a significant part of that ground support. All space vehicles require scheduled maintenance to ensure operability and performance. In addition, components of any vehicle are not one-hundred percent reliable so they exhibit random failures. Once detected, a failure initiates unscheduled maintenance on the vehicle. Maintenance decreases the number of missions which can be completed by keeping vehicles out of service so that the time between the completion of one mission and the start of the next is increased. Maintenance also requires resources such as people, facilities, tooling, and spare parts. Assessing the mission capability and resource requirements of any new space vehicle, in addition to performance specification, is necessary to predict the life cycle cost and success of the vehicle. Maintenance and logistics support has been modeled by computer simulation to estimate mission capability and resource requirements for evaluation of proposed space vehicles. The simulation was written with Simulation Language for Alternative Modeling II (SLAM II) for execution on a personal computer. For either one or a fleet of space vehicles, the model simulates the preflight maintenance checks, the mission and return to earth, and the post flight maintenance in preparation to be sent back into space. THe model enables prediction of the number of missions possible and vehicle turn-time (the time between completion of one mission and the start of the next) given estimated values for component reliability and maintainability. The model also facilitates study of the manpower and vehicle requirements for the proposed vehicle to meet its desired mission rate. This is the 3rd part of a 3 part technical report.

  13. Models for the active site in [FeFe] hydrogenase with iron-bound ligands derived from bis-, tris-, and tetrakis(mercaptomethyl)silanes.

    PubMed

    Apfel, Ulf-Peter; Troegel, Dennis; Halpin, Yvonne; Tschierlei, Stefanie; Uhlemann, Ute; Görls, Helmar; Schmitt, Michael; Popp, Jürgen; Dunne, Peter; Venkatesan, Munuswamy; Coey, Michael; Rudolph, Manfred; Vos, Johannes G; Tacke, Reinhold; Weigand, Wolfgang

    2010-11-01

    A series of multifunctional (mercaptomethyl)silanes of the general formula type R(n)Si(CH(2)SH)(4-n) (n = 0-2; R = organyl) was synthesized, starting from the corresponding (chloromethyl)silanes. They were used as multidentate ligands for the conversion of dodecacarbonyltriiron, Fe(3)(CO)(12), into iron carbonyl complexes in which the deprotonated (mercaptomethyl)silanes act as μ-bridging ligands. These complexes can be regarded as models for the [FeFe] hydrogenase. They were characterized by elemental analyses (C, H, S), NMR spectroscopic studies ((1)H, (13)C, (29)Si), and single-crystal X-ray diffraction. Their electrochemical properties were investigated by cyclic voltammetry to disclose a new mechanism for the formation of dihydrogen catalyzed by these compounds, whereby one sulfur atom was protonated in the catalytic cycle. The reaction of the tridentate ligand MeSi(CH(2)SH)(3) with Fe(3)(CO)(12) yielded a tetranuclear cluster compound. A detailed investigation by X-ray diffraction, electrochemical, Raman, Mössbauer, and susceptibility techniques indicates that for this compound initially [Fe(2){μ-MeSi(CH(2)S)(2)CH(2)SH}(CO)(6)] is formed. This dinuclear complex, however, is slowly transformed into the tetranuclear species [Fe(4){μ-MeSi(CH(2)S)(3)}(2)(CO)(8)]. PMID:20873759

  14. Development of an FE model of the rat head subjected to air shock loading.

    PubMed

    Zhu, Feng; Mao, Haojie; Dal Cengio Leonardi, Alessandra; Wagner, Christina; Chou, Clifford; Jin, Xin; Bir, Cynthia; Vandevord, Pamela; Yang, King H; King, Albert I

    2010-11-01

    As early as the 1950's, Gurdjian and colleagues (Gurdjian et al. 1955) observed that brain injuries could occur by direct pressure loading without any global head accelerations. This pressure-induced injury mechanism was "forgotten" for some time and is being rekindled due to the many mild traumatic brain injuries attributed to blast overpressure. The aim of the current study was to develop a finite element (FE) model to predict the biomechanical response of rat brain under a shock tube environment. The rat head model, including more than 530,000 hexahedral elements with a typical element size of 100 to 300 microns was developed based on a previous rat brain model for simulating a blunt controlled cortical impact. An FE model, which represents gas flow in a 0.305-m diameter shock tube, was formulated to provide input (incident) blast overpressures to the rat model. It used an Eulerian approach and the predicted pressures were verified with experimental data. These two models were integrated and an arbitrary Lagrangian-Eulerian (ALE) fluid-structure coupling algorithm was then utilized to simulate the interaction of the shock wave with the rat head. The FE model-predicted pressure-time histories at the cortex and in the lateral ventricle were in reasonable agreement with those obtained experimentally. Further examination of the FE model predictions revealed that pressure amplification, caused by shock wave reflection at the interface of the materials with distinct wave impedances, was found in the skull. The overpressures in the anterior and posterior regions were 50% higher than those at the vertex and central regions, indicating a higher possibility of injuries in the coup and contrecoup sites. At an incident pressure of 85 kPa, the shear stress and principal strain in the brain remained at a low level, implying that they are not the main mechanism causing injury in the current scenario. PMID:21512910

  15. The subthalamic nucleus part II: modelling and simulation of activity.

    PubMed

    Heida, Tjitske; Marani, Enrico; Usunoff, Kamen G

    2008-01-01

    Part I of The Subthalamic Nucleus (volume 198) (STN) accentuates the gap between experimental animal and human information concerning subthalamic development, cytology, topography and connections.The light and electron microscopical cytology focuses on the open nucleus concept and the neuronal types present in the STN. The cytochemistry encompasses enzymes, NO, glial fibrillary acidic protein (GFAP), calcium binding proteins, and receptors (dopamine, cannabinoid, opioid, glutamate, gamma-aminobutyric acid (GABA), serotonin, cholinergic, and calcium channels). The ontogeny of the subthalamic cell cord is also reviewed. The topography concerns the rat, cat, baboon and human STN. The descriptions of the connections are also given from a historical point of view. Recent tracer studies on the rat nigro-subthalamic connection revealed contralateral projections. This monograph (Part II of the two volumes) on the subthalamic nucleus (STN) starts with a systemic model of the basal ganglia to evaluate the position of the STN in the direct, indirect and hyperdirect pathways. A summary of in vitro studies is given, describing STN spontaneous activity as well as responses to depolarizing and hyperpolarizing inputs and high-frequency stimulation. STN bursting activity and the underlying ionic mechanisms are investigated. Deep brain stimulation used for symptomatic treatment of Parkinson's disease is discussed in terms of the elements that are influenced and its hypothesized mechanisms. This part of the monograph explores the pedunculopontine-subthalamic connections and summarizes attempts to mimic neurotransmitter actions of the pedunculopontine nucleus in cell cultures and high-frequency stimulation on cultured dissociated rat subthalamic neurons. STN cell models - single- and multi-compartment models and system-level models are discussed in relation to subthalamic function and dysfunction. Parts I and II are compared. PMID:18727495

  16. Effect of layer thickness in selective laser melting on microstructure of Al/5 wt.%Fe2O3 powder consolidated parts.

    PubMed

    Dadbakhsh, Sasan; Hao, Liang

    2014-01-01

    In situ reaction was activated in the powder mixture of Al/5 wt.%Fe2O3 by using selective laser melting (SLM) to directly fabricate aluminium metal matrix composite parts. The microstructural characteristics of these in situ consolidated parts through SLM were investigated under the influence of thick powder bed, 75  μm layer thickness, and 50  μm layer thickness in various laser powers and scanning speeds. It was found that the layer thickness has a strong influence on microstructural outcome, mainly attributed to its impact on oxygen content of the matrix. Various microstructural features (such as granular, coralline-like, and particulate appearance) were observed depending on the layer thickness, laser power, and scanning speed. This was associated with various material combinations such as pure Al, Al-Fe intermetallics, and Al(-Fe) oxide phases formed after in situ reaction and laser rapid solidification. Uniformly distributed very fine particles could be consolidated in net-shape Al composite parts by using lower layer thickness, higher laser power, and lower scanning speed. The findings contribute to the new development of advanced net-shape manufacture of Al composites by combining SLM and in situ reaction process. PMID:24526879

  17. Effect of Layer Thickness in Selective Laser Melting on Microstructure of Al/5 wt.%Fe2O3 Powder Consolidated Parts

    PubMed Central

    Hao, Liang

    2014-01-01

    In situ reaction was activated in the powder mixture of Al/5 wt.%Fe2O3 by using selective laser melting (SLM) to directly fabricate aluminium metal matrix composite parts. The microstructural characteristics of these in situ consolidated parts through SLM were investigated under the influence of thick powder bed, 75 μm layer thickness, and 50 μm layer thickness in various laser powers and scanning speeds. It was found that the layer thickness has a strong influence on microstructural outcome, mainly attributed to its impact on oxygen content of the matrix. Various microstructural features (such as granular, coralline-like, and particulate appearance) were observed depending on the layer thickness, laser power, and scanning speed. This was associated with various material combinations such as pure Al, Al-Fe intermetallics, and Al(-Fe) oxide phases formed after in situ reaction and laser rapid solidification. Uniformly distributed very fine particles could be consolidated in net-shape Al composite parts by using lower layer thickness, higher laser power, and lower scanning speed. The findings contribute to the new development of advanced net-shape manufacture of Al composites by combining SLM and in situ reaction process. PMID:24526879

  18. Slag Behavior in Gasifiers. Part II: Constitutive Modeling of Slag

    SciTech Connect

    Massoudi, Mehrdad; Wang, Ping

    2013-02-07

    The viscosity of slag and the thermal conductivity of ash deposits are among two of the most important constitutive parameters that need to be studied. The accurate formulation or representations of the (transport) properties of coal present a special challenge of modeling efforts in computational fluid dynamics applications. Studies have indicated that slag viscosity must be within a certain range of temperatures for tapping and the membrane wall to be accessible, for example, between 1,300 °C and 1,500 °C, the viscosity is approximately 25 Pa·s. As the operating temperature decreases, the slag cools and solid crystals begin to form. Since slag behaves as a non-linear fluid, we discuss the constitutive modeling of slag and the important parameters that must be studied. We propose a new constitutive model, where the stress tensor not only has a yield stress part, but it also has a viscous part with a shear rate dependency of the viscosity, along with temperature and concentration dependency, while allowing for the possibility of the normal stress effects. In Part I, we reviewed, identify and discuss the key coal ash properties and the operating conditions impacting slag behavior.

  19. Modeling Fe0 permeable reactive barriers for groundwater remediation

    NASA Astrophysics Data System (ADS)

    Carniato, Luca; Schoups, Gerrit; Seuntjens, Piet; Bastiaens, Leen

    2010-05-01

    Remediation of groundwater pollution has traditionally been achieved by energy-intensive and drastic methods such as pump and treat (P&T) systems. Recently, more economically viable and less invasive methods such as permeable reactive barriers have been used to clean up a wide variety of groundwater pollutants (volatile organic compounds, VOCl). Permeable reactive barriers are installed in the subsurface and the naturally present hydraulic gradient makes the groundwater flow through the barrier where the contaminants are removed by different removal processes (biodegradation, sorption, precipitation, chemical destruction). Effective application of these techniques requires a solid understanding of the site-specific hydrogeological and biochemical conditions, as well as a predictive assessment of long-term remediation efficiency. For example, secondary mineral precipitation has been shown to reduce reactivity and efficiency of permeable reactive barriers and the interactions between biological and chemical processes may also influence the long-term efficiency of such systems. In this study a multi-component transport model based on PHAST USGS has been developed to simulate the removal processes in the barrier and to make quantitative predictions about the long-term efficiency of the system. In particular the modelling approach will be presented together with the model application in lab-scale experiments and in field.

  20. Critical Assessment and Thermodynamic Modeling of the Al-Fe-O System

    NASA Astrophysics Data System (ADS)

    Shishin, Denis; Prostakova, Viktoria; Jak, Evgueni; Decterov, Sergei A.

    2016-02-01

    A complete literature review, critical evaluation, and thermodynamic modeling of the phase diagrams and thermodynamic properties of phases in the Al-Fe-O system at 1 atm total pressure are presented. Optimized model equations for the thermodynamic properties of all phases are obtained, which reproduce all available thermodynamic and phase-equilibrium data within experimental error limits from 298.15 K (25 °C) to above the liquidus temperatures at all compositions and oxygen partial pressures from metal saturation to 1 atm. The complex phase relationships in the system have been elucidated, and discrepancies among the data have been resolved. The database of the model parameters can be used along with software for Gibbs-energy minimization in order to calculate all thermodynamic properties and any type of phase diagram section. The modified quasichemical model was used for the liquid oxide phase. A sublattice model, based upon the Compound Energy Formalism, was developed for spinel, which expands from magnetite, Fe3O4, to hercynite, FeAl2O4. The distribution of cations between octahedral and tetrahedral sites and oxygen nonstoichiometry in spinel are taken into account. The model for metallic liquid assumes random mixing of associates: Fe, Al, O, AlO, and Al2O. It describes well the minimum that is observed on the solubility of oxygen in liquid iron as a function of the Al content. The solid solution between hematite and corundum exhibiting a miscibility gap, as well as a small solubility of Al2O3 in wüstite are quantitatively described by a simple Bragg-Williams model.

  1. Spin excitations in a model of FeSe with orbital ordering

    NASA Astrophysics Data System (ADS)

    Kreisel, A.; Mukherjee, Shantanu; Hirschfeld, P. J.; Andersen, Brian M.

    2015-12-01

    We present a theoretical study of the dynamical spin susceptibility for the intriguing Fe-based superconductor FeSe, based on a tight-binding model developed to account for the temperature-dependent band structure in this system. The model allows for orbital ordering in the dx z/dy z channel below the structural transition and presents a strongly C4-symmetry-broken Fermi surface at low temperatures which accounts for the nematic properties of this material. The calculated spin excitations are peaked at wave vector (π ,0 ) in the 1-Fe Brillouin zone, with a broad maximum at energies of order a few meV. In this range, the occurrence of superconductivity sharpens this peak in energy, creating a (π ,0 ) "neutron resonance" as seen in recent experiments. With the exception of the quite low energy scale of these fluctuations, these results are roughly similar to standard behavior in Fe pnictide systems. At higher energies, however, intensity increases and shifts to wave vectors along the (π ,0 )-(π ,π ) line. We compare with existing inelastic neutron experiments and NMR data, and give predictions for further studies.

  2. The catalytic ozonization of model lignin compounds in the presence of Fe(III) ions

    NASA Astrophysics Data System (ADS)

    Ben'ko, E. M.; Mukovnya, A. V.; Lunin, V. V.

    2007-05-01

    The ozonization of several model lignin compounds (guaiacol, 2,6-dimethoxyphenol, phenol, and vanillin) was studied in acid media in the presence of iron(III) ions. It was found that Fe3+ did not influence the initial rate of the reactions between model phenols and ozone but accelerated the oxidation of intermediate ozonolysis products. The metal concentration dependences of the total ozone consumption and effective rate constants of catalytic reaction stages were determined. Data on reactions in the presence of oxalic acid as a competing chelate ligand showed that complex formation with Fe3+ was the principal factor that accelerated the ozonolysis of model phenols at the stage of the oxidation of carboxylic dibasic acids and C2 aldehydes formed as intermediate products.

  3. Fe–N2/CO complexes that model a possible role for the interstitial C atom of FeMo-cofactor (FeMoco)

    PubMed Central

    Rittle, Jonathan; Peters, Jonas C.

    2013-01-01

    We report here a series of four- and five-coordinate Fe model complexes that feature an axial tri(silyl)methyl ligand positioned trans to a substrate-binding site. This arrangement is used to crudely model a single-belt Fe site of the FeMo-cofactor that might bind N2 at a position trans to the interstitial C atom. Reduction of a trigonal pyramidal Fe(I) complex leads to uptake of N2 and subsequent functionalization furnishes an open-shell Fe–diazenido complex. A related series of five-coordinate Fe–CO complexes stable across three redox states is also described. Spectroscopic, crystallographic, and Density Functional Theory (DFT) studies of these complexes suggest that a decrease in the covalency of the Fe–Calkyl interaction occurs upon reduction and substrate binding. This leads to unusually long Fe–Calkyl bond distances that reflect an ionic Fe–C bond. The data presented are contextualized in support of a hypothesis wherein modulation of a belt Fe–C interaction in the FeMo-cofactor facilitates substrate binding and reduction. PMID:24043796

  4. Hydrogen Activation by Biomimetic [NiFe]-Hydrogenase Model Containing Protected Cyanide Cofactors

    PubMed Central

    Manor, Brian C.; Rauchfuss, Thomas B.

    2013-01-01

    Described are experiments that allow incorporation of cyanide cofactors and hydride substrate into active site models [NiFe]-hydrogenases (H2ases). Complexes of the type (CO)2(CN)2Fe(pdt)Ni(dxpe), (dxpe = dppe, 1; dxpe = dcpe, 2) bind the Lewis acid B(C6F5)3 (BArF3) to give the adducts (CO)2(CNBArF3)2Fe(pdt)Ni(dxpe), (1(BArF3)2, 2(BArF3)2). Upon decarbonylation using amine oxides, these adducts react with H2 to give hydrido derivatives Et4N[(CO)(CNBArF3)2Fe(H)(pdt)Ni(dxpe)], (dxpe = dppe, Et4N[H3(BArF3)2]; dxpe = dcpe, Et4N[H4(BArF3)2]). Crystallographic analysis shows that Et4N[H3(BArF3)2] generally resembles the active site of the enzyme in the reduced, hydride-containing states (Ni-C/R). The Fe-H…Ni center is unsymmetrical with rFe-H = 1.51(3) and rNi-H = 1.71(3) Å. Both crystallographic and 19F NMR analysis show that the CNBArF3− ligands occupy basal and apical sites. Unlike cationic Ni-Fe hydrides, [H3(BArF3)2]− and [H4(BArF3)2]− oxidize at mild potentials, near the Fc+/0 couple. Electrochemical measurements indicate that in the presence of base, [H3(BArF3)2]− catalyzes the oxidation of H2. NMR evidence indicates dihydrogen bonding between these anionic hydrides and ammonium salts, which is relevant to the mechanism of hydrogenogenesis. In the case of Et4N[H3(BArF3)2], strong acids such as HCl induce H2 release to give the chloride Et4N[(CO)(CNBArF3)2Fe(pdt)(Cl)Ni(dppe)]. PMID:23899049

  5. Purified glycosaminoglycans from cooked haddock may enhance Fe uptake via endocytosis in a Caco-2 cell culture model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study aims to understand the enhancing effect of glycosaminoglycans (GAGs), such as chondroitin/dermatan structures, on Fe uptake to Caco-2 cells. High sulfated GAGs were selectively purified from cooked haddock. An in vitro digestion/Caco-2 cell culture model was used to evaluate Fe uptake (ce...

  6. Test of level density models from reactions of {sup 6}Li on {sup 58}Fe and {sup 7}Li on {sup 57}Fe

    SciTech Connect

    Oginni, B. M.; Grimes, S. M.; Voinov, A. V.; Adekola, A. S.; Brune, C. R.; Carter, D. E.; Heinen, Z.; Jacobs, D.; Massey, T. N.; O'Donnell, J. E.; Schiller, A.

    2009-09-15

    The reactions of {sup 6}Li on {sup 58}Fe and {sup 7}Li on {sup 57}Fe have been studied at 15 MeV beam energy. These two reactions produce the same compound nucleus, {sup 64}Cu. The charged particle spectra were measured at backward angles. The data obtained have been compared with Hauser-Feshbach model calculations. The level density parameters of {sup 63}Ni and {sup 60}Co have been obtained from the particle evaporation spectra. We also find contributions from the break up of the lithium projectiles to the low energy region of the {alpha} spectra.

  7. Experimental Investigation and Thermodynamic Modeling of the B2O3-FeO-Fe2O3-Nd2O3 System for Recycling of NdFeB Magnet Scrap

    NASA Astrophysics Data System (ADS)

    Jakobsson, Lars Klemet; Tranell, Gabriella; Jung, In-Ho

    2016-07-01

    NdFeB magnet scrap is an alternative source of neodymium that could have a significantly lower impact on the environment than current mining and extraction processes. Neodymium can be readily oxidized in the presence of oxygen, which makes it easy to recover neodymium in oxide form. Thermochemical data and phase diagrams for neodymium oxide containing systems is, however, very limited. Thermodynamic modeling of the B2O3-FeO-Fe2O3-Nd2O3 system was hence performed to obtain accurate phase diagrams and thermochemical properties of the system. Key phase diagram experiments were also carried out for the FeO-Nd2O3 system in saturation with iron to improve the accuracy of the present modeling. The modified quasichemical model was used to describe the Gibbs energy of the liquid oxide phase. The Gibbs energy functions of the liquid phase and the solids were optimized to reproduce all available and reliable phase diagram data, and thermochemical properties of the system. Finally the optimized database was applied to calculate conditions for selective oxidation of neodymium from NdFeB magnet waste.

  8. Spectral modeling of Fe XVII pumped by a free-electron x-ray laser

    NASA Astrophysics Data System (ADS)

    Clementson, Joel

    2011-09-01

    The atomic structure and x-ray pumping of neonlike Fe xvii have been calculated and modeled under free-electron laser excitation conditions using the Flexible Atomic Code. Specifically, pumping of the (2p3/23s1/2)2,1, (2p1/23s1/2)1, (2p3/23d5/2)1, and (2p1/23d3/2)1 levels that connect with the ground state (2s22p6)0 by the so-called M2, 3G, 3F, 3D, and 3C transitions have been studied. In addition, the spectrum of sodiumlike Fe xvi has been modeled to account for possible line coincidences with the neonlike spectrum. The calculations include oscillator strengths, radiative transition probability rates, autoionization rates, non-resonant photoionization cross sections, and line emissivities.

  9. Effects of two-temperature model on cascade evolution in Ni and NiFe

    DOE PAGESBeta

    Samolyuk, German D.; Xue, Haizhou; Bei, Hongbin; Weber, William J.

    2016-07-05

    We perform molecular dynamics simulations of Ni ion cascades in Ni and equiatomic NiFe under the following conditions: (a) classical molecular dynamics (MD) simulations without consideration of electronic energy loss, (b) classical MD simulations with the electronic stopping included, and (c) using the coupled two-temperature MD (2T-MD) model that incorporates both the electronic stopping and the electron-phonon interactions. Our results indicate that the electronic e ects are more profound in the higher energy cascades and that the 2T-MD model results in a smaller amount of surviving damage and smaller defect clusters, while less damage is produced in NiFe than inmore » Ni.« less

  10. Branch Flow Model: Relaxations and Convexification-Part II

    SciTech Connect

    Farivar, M; Low, SH

    2013-08-01

    We propose a branch flow model for the analysis and optimization of mesh as well as radial networks. The model leads to a new approach to solving optimal power flow (OPF) that consists of two relaxation steps. The first step eliminates the voltage and current angles and the second step approximates the resulting problem by a conic program that can be solved efficiently. For radial networks, we prove that both relaxation steps are always exact, provided there are no upper bounds on loads. For mesh networks, the conic relaxation is always exact but the angle relaxation may not be exact, and we provide a simple way to determine if a relaxed solution is globally optimal. We propose convexification of mesh networks using phase shifters so that OPF for the convexified network can always be solved efficiently for an optimal solution. We prove that convexification requires phase shifters only outside a spanning tree of the network and their placement depends only on network topology, not on power flows, generation, loads, or operating constraints. Part I introduces our branch flow model, explains the two relaxation steps, and proves the conditions for exact relaxation. Part II describes convexification of mesh networks, and presents simulation results.

  11. Branch Flow Model: Relaxations and Convexification-Part I

    SciTech Connect

    Farivar, M; Low, SH

    2013-08-01

    We propose a branch flow model for the analysis and optimization of mesh as well as radial networks. The model leads to a new approach to solving optimal power flow (OPF) that consists of two relaxation steps. The first step eliminates the voltage and current angles and the second step approximates the resulting problem by a conic program that can be solved efficiently. For radial networks, we prove that both relaxation steps are always exact, provided there are no upper bounds on loads. For mesh networks, the conic relaxation is always exact but the angle relaxation may not be exact, and we provide a simple way to determine if a relaxed solution is globally optimal. We propose convexification of mesh networks using phase shifters so that OPF for the convexified network can always be solved efficiently for an optimal solution. We prove that convexification requires phase shifters only outside a spanning tree of the network and their placement depends only on network topology, not on power flows, generation, loads, or operating constraints. Part I introduces our branch flow model, explains the two relaxation steps, and proves the conditions for exact relaxation. Part II describes convexification of mesh networks, and presents simulation results.

  12. Magnetocrystalline anisotropy energy of Fe (001) and Fe (110) slabs and nanoclusters: A detailed local analysis within a tight-binding model

    NASA Astrophysics Data System (ADS)

    Li, Dongzhe; Smogunov, Alexander; Barreteau, Cyrille; Ducastelle, François; Spanjaard, Daniel

    2013-12-01

    We report tight-binding (TB) calculations of magnetocrystalline anisotropy energy (MAE) of iron slabs and nanoclusters with a particular focus on local analysis. After clarifying various concepts and formulations for the determination of MAE, we apply our realistic TB model to the analysis of the magnetic anisotropy of Fe (001), Fe (110) slabs and of two large Fe clusters with (001) and (110) facets only: a truncated pyramid and a truncated bipyramid containing 620 and 1096 atoms, respectively. It is shown that the MAE of slabs originates mainly from outer layers; a small contribution from the subsurface gives rise, however, to an oscillatory behavior for large thicknesses. Interestingly, the MAE of the nanoclusters considered is almost solely due to (001) facets and the base perimeter of the pyramid. We believe that this fact could be used to efficiently control the anisotropy of iron nanoparticles and could also have consequences on their spin dynamics.

  13. Atomic data for a five-configuration model of Fe XIV

    NASA Technical Reports Server (NTRS)

    Bhatia, A. K.; Kastner, S. O.

    1993-01-01

    Collision strengths calculated in the distorted wave approximation are presented for electron excitation of Fe XIV at incident energies of 10, 20 and 30 Rydbergs. Configurations 3s(2)3p, 3s3p(2), 3s(2)3d, 3p(3), and 3s3p3d are included, comprising 40 levels, and wave function mixing coefficients are tabulated. Radiative transition rates are given for the same model using the Superstructure program.

  14. Magnetic, magnetocaloric properties and phenomenological model in amorphous Fe60Ru20B20 alloy

    NASA Astrophysics Data System (ADS)

    Boutahar, A.; Lassri, H.; Hlil, E. K.

    2015-11-01

    Magnetic, magnetocaloric properties and phenomenological model of amorphous Fe60Ru20B20 alloy are investigated in detail. The amorphous alloy has been synthesized using melt spinning method. The magnetic transition nature undergoes a second-order magnetic phase transition from ferromagnetic to paramagnetic states with a Curie temperature of 254 K. Basis on the thermodynamic Maxwell's relation, magnetic entropy change (-ΔSM) is calculated. Further, we also report a theoretical investigation of the magnetocaloric effect using a phenomenological model. The best model parameters and their variation with temperature and the magnetic field were determined. The theoretical predictions are found to agree closely with experimental measurements.

  15. New Light on NO Bonding in Fe(III) Heme Proteins from Resonance Raman Spectroscopy and DFT Modeling

    PubMed Central

    Soldatova, Alexandra V.; Ibrahim, Mohammed; Olson, John S.; Czernuszewicz, Roman S.; Spiro, Thomas G.

    2010-01-01

    Visible and ultraviolet resonance Raman (RR) spectra are reported for FeIII(NO) adducts of myoglobin variants with altered polarity in the distal heme pockets. The stretching frequencies of the FeIII–NO and N–O bonds, νFeN and νNO, are negatively correlated, consistent with backbonding. However, the correlation shifts to lower νNO for variants lacking a distal histidine. DFT modeling reproduces the shifted correlations, and shows the shift to be associated with the loss of a lone-pair donor interaction from the distal histidine that selectively strengthens the N–O bond. However, when the model contains strongly electron-withdrawing substituents at the heme β-positions, νFeN and νNO become positively correlated. This effect results from FeIII–N–O bending, which is induced by lone pair donation to the NNO atom. Other mechanisms for bending are discussed, which likewise lead to a positive νFeN/νNO correlation, including thiolate ligation in heme proteins and electron-donating meso-substituents in heme models. The νFeN/νNO data for the Fe(III) complexes are reporters of heme pocket polarity and the accessibility of lone pair, Lewis base donors. Implications for biologically important processes, including NO binding, reductive nitrosylation and NO reduction, are discussed. PMID:20218710

  16. Post-irradiation annealing behavior of neutron-irradiated FeCu, FeMnNi and FeMnNiCu model alloys investigated by means of small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Bergner, F.; Ulbricht, A.; Lindner, P.; Keiderling, U.; Malerba, L.

    2014-11-01

    Neutron irradiation of reactor pressure vessel steels gives rise to the formation of thermodynamically stable and unstable nano-features. The present work is focused on the stability of Cu-, Mn- and Ni-containing solute clusters in model alloys exposed to post-irradiation annealing. Fe0.1Cu, Fe1.2Mn0.7Ni and Fe1.2Mn0.7Ni0.1Cu (wt%) model alloys irradiated up to neutron exposures of 0.1 and 0.19 dpa (displacements per atom) were annealed at stepwise increasing temperatures in the range from 300 °C (i.e. near irradiation temperature) to 500 °C and characterized by means of small-angle neutron scattering (SANS). We have found characteristic differences in the annealing behavior of the alloys. In particular, there is a non-trivial (synergistic-antagonistic) interplay of Mn/Ni and Cu.

  17. The locations of recent supernovae near the Sun from modelling 60Fe transport

    NASA Astrophysics Data System (ADS)

    Breitschwerdt, D.; Feige, J.; Schulreich, M. M.; Avillez, M. A. De.; Dettbarn, C.; Fuchs, B.

    2016-04-01

    The signature of 60Fe in deep-sea crusts indicates that one or more supernovae exploded in the solar neighbourhood about 2.2 million years ago. Recent isotopic analysis is consistent with a core-collapse or electron-capture supernova that occurred 60 to 130 parsecs from the Sun. Moreover, peculiarities in the cosmic ray spectrum point to a nearby supernova about two million years ago. The Local Bubble of hot, diffuse plasma, in which the Solar System is embedded, originated from 14 to 20 supernovae within a moving group, whose surviving members are now in the Scorpius-Centaurus stellar association. Here we report calculations of the most probable trajectories and masses of the supernova progenitors, and hence their explosion times and sites. The 60Fe signal arises from two supernovae at distances between 90 and 100 parsecs. The closest occurred 2.3 million years ago at present-day galactic coordinates l = 327°, b = 11°, and the second-closest exploded about 1.5 million years ago at l = 343°, b = 25°, with masses of 9.2 and 8.8 times the solar mass, respectively. The remaining supernovae, which formed the Local Bubble, contribute to a smaller extent because they happened at larger distances and longer ago (60Fe has a half-life of 2.6 million years). There are uncertainties relating to the nucleosynthesis yields and the loss of 60Fe during transport, but they do not influence the relative distribution of 60Fe in the crust layers, and therefore our model reproduces the measured relative abundances very well.

  18. The locations of recent supernovae near the Sun from modelling (60)Fe transport.

    PubMed

    Breitschwerdt, D; Feige, J; Schulreich, M M; de Avillez, M A; Dettbarn, C; Fuchs, B

    2016-04-01

    The signature of (60)Fe in deep-sea crusts indicates that one or more supernovae exploded in the solar neighbourhood about 2.2 million years ago. Recent isotopic analysis is consistent with a core-collapse or electron-capture supernova that occurred 60 to 130 parsecs from the Sun. Moreover, peculiarities in the cosmic ray spectrum point to a nearby supernova about two million years ago. The Local Bubble of hot, diffuse plasma, in which the Solar System is embedded, originated from 14 to 20 supernovae within a moving group, whose surviving members are now in the Scorpius-Centaurus stellar association. Here we report calculations of the most probable trajectories and masses of the supernova progenitors, and hence their explosion times and sites. The (60)Fe signal arises from two supernovae at distances between 90 and 100 parsecs. The closest occurred 2.3 million years ago at present-day galactic coordinates l = 327°, b = 11°, and the second-closest exploded about 1.5 million years ago at l = 343°, b = 25°, with masses of 9.2 and 8.8 times the solar mass, respectively. The remaining supernovae, which formed the Local Bubble, contribute to a smaller extent because they happened at larger distances and longer ago ((60)Fe has a half-life of 2.6 million years). There are uncertainties relating to the nucleosynthesis yields and the loss of (60)Fe during transport, but they do not influence the relative distribution of (60)Fe in the crust layers, and therefore our model reproduces the measured relative abundances very well. PMID:27078566

  19. Signal classification using global dynamical models, Part I: Theory

    SciTech Connect

    Kadtke, J.; Kremliovsky, M.

    1996-06-01

    Detection and classification of signals is one of the principal areas of signal processing, and the utilization of nonlinear information has long been considered as a way of improving performance beyond standard linear (e.g. spectral) techniques. Here, we develop a method for using global models of chaotic dynamical systems theory to define a signal classification processing chain, which is sensitive to nonlinear correlations in the data. We use it to demonstrate classification in high noise regimes (negative SNR), and argue that classification probabilities can be directly computed from ensemble statistics in the model coefficient space. We also develop a modification for non-stationary signals (i.e. transients) using non-autonomous ODEs. In Part II of this paper, we demonstrate the analysis on actual open ocean acoustic data from marine biologics. {copyright} {ital 1996 American Institute of Physics.}

  20. On the properties of silica-supported bimetallic Fe-Cu catalysts. Part 1. Preparation and characterization

    SciTech Connect

    Wielers, A.F.H.; Hop, C.E.C.A.; van Beijnum, J.; Geus, J.W. ); van der Kraan, A.M. )

    1990-02-01

    In this work a series of silica-supported bimetallic iron-copper catalysts has been prepared and characterized. The bimetallic catalysts were prepared via homogeneous deposition-precipitation involving a procedure in which first copper ions (as copper hydrosilicate) and consecutively iron(III) ions (as goethite) are precipitated onto the support. The results show that copper facilitates the reduction of iron(III) to iron(II) (which is present as iron(II)silicate) as well as the reduction to zero-valent iron. In the reduced iron/copper catalyst zero-valent iron is present as monometallic {alpha}-Fe particles and as iron clusters in bimetallic Fe-Cu particles. The relative amounts of the various iron species vary with the overall composition. Whereas the surfaces of the freshly reduced bimetallic particles are not extensively enriched in one of the constituents, prolonged CO exposure at room temperature leads to a considerable iron enrichment.

  1. Modeling of afforestation possibilities on one part of Hungary

    NASA Astrophysics Data System (ADS)

    Bozsik, Éva; Riczu, Péter; Tamás, János; Burriel, Charles; Helilmeier, Hermann

    2015-04-01

    Agroforestry systems are part of the history of the European Union rural landscapes, but the regional increase of size of agricultural parcels had a significant effect on European land use in the 20th century, thereby it has radically reduced the coverage of natural forest. However, this cause conflicts between interest of agricultural and forestry sectors. The agroforestry land uses could be a solution of this conflict management. One real - ecological - problem with the remnant forests and new forest plantation is the partly missing of network function without connecting ecological green corridors, the other problem is verifiability for the agroforestry payment system, monitoring the arable lands and plantations. Remote sensing methods are currently used to supervise European Union payments. Nowadays, next to use satellite imagery the airborne hyperspectral and LiDAR (Light Detection And Ranging) remote sensing technologies are becoming more widespread use for nature, environmental, forest, agriculture protection, conservation and monitoring and it is an effective tool for monitoring biomass production. In this Hungarian case study we made a Spatial Decision Support System (SDSS) to create agroforestry site selection model. The aim of model building was to ensure the continuity of ecological green corridors, maintain the appropriate land use of regional endowments. The investigation tool was the more widely used hyperspectral and airborne LiDAR remote sensing technologies which can provide appropriate data acquisition and data processing tools to build a decision support system

  2. Comparisons of Na densities, Fe densities, and temperature measured over south polar cap with model predictions

    NASA Astrophysics Data System (ADS)

    Chu, X.; Gardner, C. S.; Vondrak, T.; Murray, B.; Plane, J. M.; Roble, R. G.; Espy, P. J.; Kawahara, T.

    Mesospheric Na and Fe layer densities and temperatures were measured by lidar systems at the South Pole, Syowa (69S, 39E), and Rothera (67.5S, 68.0W) during the past several years. Comparison of the wintertime temperatures measured above these sites with TIME-GCM predictions, suggests that the model over-estimates the compressional heating associated with downwelling. When simulating the winter Na and Fe densities at the pole using the UEA 1-D chemistry models, a 2-D general circulation model SOCRATES was used to predict the meridional and downward vertical transportation of O, H, etc. from the sunlit lower latitude into the polar vortex. However, the simulation indicates that the circulation, especially downward transport into the polar vortex, is overestimated by the general circulation model. Thus, the wintertime Na layer nearly disappears in the chemistry model, which does not agree with the maximum Na abundance observed in winter. In summer, the model correctly predicts the observed depletion of the metal atoms below 90 km. This results from the uptake of the metals onto ice particles, which seem to be a persistent feature of the summertime upper mesosphere at high latitudes. This paper will show that the observed seasonal behavior of the metal layers provides a rigorous test of general circulation models in the upper mesosphere.

  3. Multiaxial cyclic ratcheting in coiled tubing -- Part 1: Theoretical modeling

    SciTech Connect

    Rolovic, R.; Tipton, S.M.

    2000-04-01

    Coiled tubing is a long, continuous string of steel tubing that is used in the oil well drilling and servicing industry. Bending strains imposed on coiled tubing as it is deployed and retrieved from a well are considerably into the plastic regime and can be as high as 3%. Progressive growth of tubing diameter occurs when tubing is cyclically bent-straightened under constant internal pressure, regardless of the fact that the hoop stress imposed by typical pressure levels is well below the material's yield strength. A new incremental plasticity model is proposed in this study that can predict multiaxial cyclic ratcheting in coiled tubing more accurately than the conventional plasticity models. A new hardening rule is presented based on published experimental observations. The model also implements a new plastic modulus function. The predictions based on the new theory correlate well with experimental results presented in Part 2 of this paper. Some previously unexpected trends in coiled tubing deformation behavior were observed and correctly predicted using the proposed model.

  4. An Integrated Modeling Approach for Predicting Process Maps of Residual Stress and Distortion in a Laser Weld: A Combined CFD-FE Methodology

    NASA Astrophysics Data System (ADS)

    Turner, Richard P.; Panwisawas, Chinnapat; Sovani, Yogesh; Perumal, Bama; Ward, R. Mark; Brooks, Jeffery W.; Basoalto, Hector C.

    2016-07-01

    Laser welding has become an important joining methodology within a number of industries for the structural joining of metallic parts. It offers a high power density welding capability which is desirable for deep weld sections, but is equally suited to performing thinner welded joints with sensible amendments to key process variables. However, as with any welding process, the introduction of severe thermal gradients at the weld line will inevitably lead to process-induced residual stress formation and distortions. Finite element (FE) predictions for weld simulation have been made within academia and industrial research for a number of years, although given the fluid nature of the molten weld pool, FE methodologies have limited capabilities. An improvement upon this established method would be to incorporate a computational fluid dynamics (CFD) model formulation prior to the FE model, to predict the weld pool shape and fluid flow, such that details can be fed into FE from CFD as a starting condition. The key outputs of residual stress and distortions predicted by the FE model can then be monitored against the process variables input to the model. Further, a link between the thermal results and the microstructural properties is of interest. Therefore, an empirical relationship between lamellar spacing and the cooling rate was developed and used to make predictions about the lamellar spacing for welds of different process parameters. Processing parameter combinations that lead to regions of high residual stress formation and high distortion have been determined, and the impact of processing parameters upon the predicted lamellar spacing has been presented.

  5. Influence of lipids with hydroxyl-containing head groups on Fe2+ (Cu2+)/H2O2-mediated transformation of phospholipids in model membranes.

    PubMed

    Olshyk, Viktoriya N; Melsitova, Inna V; Yurkova, Irina L

    2014-01-01

    Under condition of ROS formation in lipid membranes, free radical reactions can proceed in both hydrophobic (peroxidation of lipids, POL) and polar (free radical fragmentation) parts of the bilayer. Free-radical fragmentation is typical for the lipids containing a hydroxyl group in β-position with respect to an ester or amide bond. The present study has been undertaken to investigate free-radical transformations of phospholipids in model membranes containing lipids able to undergo fragmentation in their polar part. Liposomes from egg yolk lecithin containing saturated or monounsaturated glycero- and sphingolipids were subjected to the action of an HO* - generating system - Fe(2+)(Cu(2+))/H2O2/Asc, and the POL products were investigated. In parallel with this, the effects of monoacylglycerols and scavengers of reactive species on Fe(2+)(Cu(2+))/H2O2/Asc - mediated free-radical fragmentation of phosphatidylglycerols were studied. Hydroxyl-containing sphingolipids and glycerolipids, which undergo free-radical fragmentation under such conditions, manifested antioxidant properties in the model membranes. In the absence of HO groups in the lipid structure, the effect was either pro-oxidant or neutral. Monoacylglycerols slowed down the rate of both peroxidation in the hydrophobic part and free-radical fragmentation in the hydrophilic part of phospholipid membrane. Scavengers of reactive species inhibited the fragmentation of phosphatidylglycerol substantially. Thus, the ability of hydroxyl-containing lipids to undergo free-radical fragmentation in polar part apparently makes a substantial contribution to the mechanism of their protector action. PMID:24189590

  6. Oxide scales formed on Fe-Cr-Al-based model alloys exposed to oxygen containing molten lead

    NASA Astrophysics Data System (ADS)

    Weisenburger, A.; Jianu, A.; Doyle, S.; Bruns, M.; Fetzer, R.; Heinzel, A.; DelGiacco, M.; An, W.; Müller, G.

    2013-06-01

    Based on the state of the art oxide maps concerning oxidation behavior of Fe-Cr-Al model alloys at 800 and 1000 °C in oxygen atmosphere, ten compositions, belonging to this alloy system, were designed in order to tap the borders of the alumina stability domain, during their exposure to oxygen (10-6 wt.%) containing lead, at 400, 500 and 600 °C. Eight alloys, Fe-6Cr-6Al, Fe-8Cr-6Al, Fe-10Cr-5Al, Fe-14Cr-4Al, Fe-16Cr-4Al, Fe-6Cr-8Al, Fe-10Cr-7Al and Fe-12Cr-5Al, were found to be protected against corrosion in oxygen containing lead, either by a duplex layer (Fe3O4 + (Fe1-x-yCrxAly)3O4) or by (Fe1-x-yCrxAly)3O4, depending on the temperature at which they were exposed. Two alloys namely Fe-12Cr-7Al and Fe-16Cr-6Al were found to form transient aluminas, κ-Al2O3 (at 400 and 500 °C) and θ-Al2O3 (at 600 °C), as protective oxide scale against corrosion in oxygen containing lead. An oxide map illustrating the stability domain of alumina, grown on Fe-Cr-Al alloys when exposed to molten, oxygen containing lead, was drawn. The map includes also additional points, extracted from literature and corresponding to alumina forming alloys, when exposed to HLMs, which fit very well with our findings. Chromium and aluminium contents of 12.5-17 wt.% and 6-7.5 wt.%, respectively, are high enough to obtain thin, stable and protective alumina scales on Fe-Cr-Al-based alloys exposed to oxygen containing lead at 400, 500 and 600 °C. For the temperature range and exposure times used during the current evaluation, the growth rate of the alumina scale was low. No area with detached scale was observed and no trace of α-Al2O3 was detected.

  7. Reaction pathways of model compounds of biomass-derived oxygenates on Fe/Ni bimetallic surfaces

    NASA Astrophysics Data System (ADS)

    Yu, Weiting; Chen, Jingguang G.

    2015-10-01

    Controlling the activity and selectivity of converting biomass-derivatives to fuels and valuable chemicals is critical for the utilization of biomass feedstocks. There are primarily three classes of non-food competing biomass, cellulose, hemicellulose and lignin. In the current work, glycolaldehyde, furfural and acetaldehyde are studied as model compounds of the three classes of biomass-derivatives. Monometallic Ni(111) and monolayer (ML) Fe/Ni(111) bimetallic surfaces are studied for the reaction pathways of the three biomass surrogates. The ML Fe/Ni(111) surface is identified as an efficient surface for the conversion of biomass-derivatives from the combined results of density functional theory (DFT) calculations and temperature programmed desorption (TPD) experiments. A correlation is also established between the optimized adsorption geometry and experimental reaction pathways. These results should provide helpful insights in catalyst design for the upgrading and conversion of biomass.

  8. Nanoscale characterization of ODS Fe-9%Cr model alloys compacted by spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Heintze, C.; Hernández-Mayoral, M.; Ulbricht, A.; Bergner, F.; Shariq, A.; Weissgärber, T.; Frielinghaus, H.

    2012-09-01

    Ferritic/martensitic high-chromium steels are leading candidates for fission and fusion reactor components. Oxide dispersion strengthening is an effective way to improve properties related to thermal and irradiation-induced creep and to extend their elevated temperature applications. An extensive experimental study focusing on the microstructural characterization of oxide-dispersion strengthened Fe-9wt%Cr model alloys is reported. Several material variants were produced by means of high-energy milling of elemental powders of Fe, Cr and commercial yttria powders. Consolidation was based on spark plasma sintering. Special emphasis is placed on the characterization of the nano-particles using transmission electron microscopy, small-angle neutron scattering and atom probe tomography. The microstructure of the investigated alloys and the role of the process parameters are discussed. Implications for the reliability of the applied characterization techniques are also highlighted.

  9. Borane-Protected Cyanides as Surrogates of H-Bonded Cyanides in [FeFe]-Hydrogenase Active Site Models

    PubMed Central

    Manor, Brian C.; Ringenberg, Mark R.; Rauchfuss, Thomas B.

    2015-01-01

    Triarylborane Lewis acids bind [Fe2(pdt)-(CO)4(CN)2]2− (pdt2− = 1,3-propanedithiolate) and [Fe2(adt)(CO)4(CN)2]2− [3]2− (adt2− = 1,3-azadithiolate, HN(CH2S−)2) to give the 2:1 adducts [Fe2(xdt)-(CO)4(CNBAr3)2]2−. Attempts to prepare the 1:1 adducts [1(BAr3)]2− (Ar = Ph, C6F5) were unsuccessful, but related 1:1 adducts were obtained using the bulky borane B(C6F4-o-C6F5)3 (BArF*3). By virtue of the N-protection by the borane, salts of [Fe2(pdt)(CO)4(CNBAr3)2]2− sustain protonation to give hydrides that are stable (in contrast to [H1]−). The hydrides [H1(BAr3)2]− are 2.5–5 pKa units more acidic than the parent [H1]−. The adducts [1(BAr3)2]2− oxidize quasi-reversibly around −0.3 V versus Fc0/+ in contrast to ca. −0.8 V observed for the [1]2−/− couple. A simplified synthesis of [1]2−, [3]2−, and [Fe2(pdt)(CO)5(CN)]− ([2]−) was developed, entailing reaction of the diiron hexacarbonyl complexes with KCN in MeCN. PMID:24992155

  10. Modelling utility-scale wind power plants. Part 1: Economics

    NASA Astrophysics Data System (ADS)

    Milligan, Michael R.

    1999-10-01

    As the worldwide use of wind turbine generators continues to increase in utility-scale applications, it will become increasingly important to assess the economic and reliability impact of these intermittent resources. Although the utility industry in the United States appears to be moving towards a restructured environment, basic economic and reliability issues will continue to be relevant to companies involved with electricity generation. This article is the first of two which address modelling approaches and results obtained in several case studies and research projects at the National Renewable Energy Laboratory (NREL). This first article addresses the basic economic issues associated with electricity production from several generators that include large-scale wind power plants. An important part of this discussion is the role of unit commitment and economic dispatch in production cost models. This paper includes overviews and comparisons of the prevalent production cost modelling methods, including several case studies applied to a variety of electric utilities. The second article discusses various methods of assessing capacity credit and results from several reliability-based studies performed at NREL.

  11. Towards a Measurement of the Half-Life of {sup 60}Fe for Stellar and Early Solar System Models

    SciTech Connect

    Ostdiek, K.; Anderson, T.; Bauder, W.; Bowers, M.; Collon, P.; Dressler, R.; Greene, J.; Kutschera, W.; Lu, W.; Paul, M.

    2015-10-15

    Radioisotopes, produced in stars and ejected into the Interstellar Medium, are important for constraining stellar and early Solar System (ESS) models. In particular, the half-life of the radioisotope, Fe-60, can have an impact on calculations for the timing for ESS events, the distance to nearby Supernovae, and the brightness of individual, non-steady-state Fe gamma ray sources in the Galaxy. A half-life measurement has been undertaken at the University of Notre Dame and measurements of the Fe-60/Fe-56 concentration of our samples using Accelerator Mass Spectrometry has begun. This result will be coupled with an activity measurement of the isomeric decay in Co-60, which is the decay product of Fe. Preliminary half-life estimates of (2.53 +/- 0.24) x 10(6) years seem to confirm the recent measurement by Rugel et al. (2009). (C) 2015 Elsevier B.V. All rights reserved.

  12. Study of perpendicular anisotropy L1{sub 0}-FePt pseudo spin valves using a micromagnetic trilayer model

    SciTech Connect

    Ho, Pin; Evans, Richard F. L.; Chantrell, Roy W.; Han, Guchang; Chow, Gan-Moog; Chen, Jingsheng

    2015-06-07

    A trilayer micromagnetic model based on the Landau-Lifshitz-Bloch equation of motion is utilized to study the properties of L1{sub 0}-FePt/TiN/L1{sub 0}-FePt pseudo spin valves (PSVs) in direct comparison with experiment. Theoretical studies give an insight on the crystallographic texture, magnetic properties, reversal behavior, interlayer coupling effects, and magneto-transport properties of the PSVs, in particular, with varying thickness of the top L1{sub 0}-FePt and TiN spacer. We show that morphological changes in the FePt layers, induced by varying the FePt layer thickness, lead to different hysteresis behaviors of the samples, caused by changes in the interlayer and intralayer exchange couplings. Such effects are important for the optimization of the PSVs due to the relationship between the magnetic properties, domain structures, and the magnetoresistance of the device.

  13. EIT image reconstruction based on a hybrid FE-EFG forward method and the complete-electrode model.

    PubMed

    Hadinia, M; Jafari, R; Soleimani, M

    2016-06-01

    This paper presents the application of the hybrid finite element-element free Galerkin (FE-EFG) method for the forward and inverse problems of electrical impedance tomography (EIT). The proposed method is based on the complete electrode model. Finite element (FE) and element-free Galerkin (EFG) methods are accurate numerical techniques. However, the FE technique has meshing task problems and the EFG method is computationally expensive. In this paper, the hybrid FE-EFG method is applied to take both advantages of FE and EFG methods, the complete electrode model of the forward problem is solved, and an iterative regularized Gauss-Newton method is adopted to solve the inverse problem. The proposed method is applied to compute Jacobian in the inverse problem. Utilizing 2D circular homogenous models, the numerical results are validated with analytical and experimental results and the performance of the hybrid FE-EFG method compared with the FE method is illustrated. Results of image reconstruction are presented for a human chest experimental phantom. PMID:27203801

  14. Discriminatively trained part based model armed with biased saliency

    NASA Astrophysics Data System (ADS)

    Yu, Huapeng; Chang, Yongxin; Lu, Pei; Xu, Zhiyong; Fu, Chengyu; Wang, Yafei

    2015-02-01

    Discriminatively trained Part based Model (DPM) is one of the state-of-the-art object detectors. However, DPM complies little with real vision procedure. In this paper, we try arming DPM with biologically inspired approaches. On the one hand, we use Gabor instead of Histogram of Oriented Gradient (HOG) as low level features to simulate the receptive fields of simple cells. We show Gabor outperforms or is on par with HOG. On the other hand, we learn biased saliency of the object with the same Gabor features to simulate the search procedure of real vision. We combine DPM and biased saliency in a single Bayesian framework, which at least partially reflects the interactions between top-down and bottom-up vision procedures. We show these biologically inspired procedures can effectively improve the performance and efficiency of DPM. We present experimental results on both challenging PASCAL VOC2007 dataset and publicly available sequences.

  15. Predictions of the Hunt-Lu array model compared with measurements for the growth undercooling of Al{sub 3}Fe dendrites in Al-Fe alloys

    SciTech Connect

    Liang, D.; Jones, H.

    1997-10-01

    Earlier contributions by the authors reported the first measurements of growth temperature as a function of growth velocity V and alloy concentration C{sub 0} for a dendritic intermetallic phase (Al{sub 3}Fe, in Al-rich Al-Fe alloys). Comparison with predictions of the model of Kurz, Giovanola and Trivedi (KGT model) of dendrite growth of a needle gave predicted {Delta}T a factor between 1.1 and 2.5 above the measured values. A subsequent paper presented evidence that the Al{sub 3}Fe dendrite tips were indeed needle-like under the conditions studied, as distinct from the plate-like morphology that develops behind the dendrite tips. The KGT model predicts T{sub G} and {Delta}T on the basis that marginal stability determines the operating condition at the dendrite tip. The present purpose is to compare the measurements with predictions of the more recently developed array model of Hunt and Lu.

  16. Epitaxial Fe/Y2O3 interfaces as a model system for oxide-dispersion-strengthened ferritic alloys

    SciTech Connect

    Kaspar, Tiffany C.; Bowden, Mark E.; Wang, Chong M.; Shutthanandan, V.; Overman, Nicole R.; Van Ginhoven, Renee M.; Wirth, Brian D.; Kurtz, Richard J.

    2015-02-01

    The fundamental mechanisms underlying the superior radiation tolerance properties of oxide-dispersion-strengthened ferritic steels and nanostructured ferritic alloys are poorly understood. Thin film heterostructures of Fe/Y2O3 can serve as a model system for fundamental studies of radiation damage. Epitaxial thin films of Y2O3 were deposited by pulsed laser deposition on 8% Y:ZrO2 (YSZ) substrates with (100), (110), and (111) orientation. Metallic Fe was subsequently deposited by molecular beam epitaxy. Characterization by x-ray diffraction and Rutherford backscattering spectrometry in the channeling geometry revealed a degree of epitaxial or axiotaxial ntation for Fe(211) deposited on Y2O3(110)/YSZ(110). In contrast, Fe on Y2O3(111)/YSZ(111) was fully polycrystalline, and Fe on Y2O3(100)/YSZ(100) exhibited out-of-plane texture in the [110] direction with little or no preferential in-plane orientation. Scanning transmission electron microscopy imaging of Fe(211)/Y2O3(110)/YSZ(110) revealed a strongly islanded morphology for the Fe film, with no epitaxial grains visible in the cross-sectional sample. Well-ordered Fe grains with no orientation to the underlying Y2O3 were observed. Well-ordered crystallites of Fe with both epitaxial and non-epitaxial orientations on Y2O3 are a promising model system for fundamental studies of radiation damage phenomena. This is illustrated with preliminary results of He bubble formation following implantation with a helium ion microscope. He bubble formation is shown to preferentially occur at the Fe/Y2O3 interface.

  17. FE Modeling of Guided Wave Propagation in Structures with Weak Interfaces

    NASA Astrophysics Data System (ADS)

    Hosten, Bernard; Castaings, Michel

    2005-04-01

    This paper describes the use of a Finite Element code for modeling the effects of weak interfaces on the propagation of low order Lamb modes. The variable properties of the interface are modeled by uniform repartitions of compression and shear springs that insure the continuity of the stresses and impose a discontinuity in the displacement field. The method is tested by comparison with measurements that were presented in a previous QNDE conference (B.W.Drinkwater, M.Castaings, and B.Hosten "The interaction of Lamb waves with solid-solid interfaces", Q.N.D.E. Vol. 22, (2003) 1064-1071). The interface was the contact between a rough elastomer with high internal damping loaded against one surface of a glass plate. Both normal and shear stiffnesses of the interface were quantified from the attenuation of A0 and S0 Lamb waves caused by leakage of energy from the plate into the elastomer and measured at each step of a compressive loading. The FE model is made in the frequency domain, thus allowing the viscoelastic properties of the elastomer to be modeled by using complex moduli as input data. By introducing the interface stiffnesses in the code, the predicted guided waves attenuations are compared to the experimental results to validate the numerical FE method.

  18. Model many-body Stoner Hamiltonian for binary FeCr alloys

    NASA Astrophysics Data System (ADS)

    Nguyen-Manh, D.; Dudarev, S. L.

    2009-09-01

    We derive a model tight-binding many-body d -electron Stoner Hamiltonian for FeCr binary alloys and investigate the sensitivity of its mean-field solutions to the choice of hopping integrals and the Stoner exchange parameters. By applying the local charge-neutrality condition within a self-consistent treatment we show that the negative enthalpy-of-mixing anomaly characterizing the alloy in the low chromium concentration limit is due entirely to the presence of the on-site exchange Stoner terms and that the occurrence of this anomaly is not specifically related to the choice of hopping integrals describing conventional chemical bonding between atoms in the alloy. The Bain transformation pathway computed, using the proposed model Hamiltonian, for the Fe15Cr alloy configuration is in excellent agreement with ab initio total-energy calculations. Our investigation also shows how the parameters of a tight-binding many-body model Hamiltonian for a magnetic alloy can be derived from the comparison of its mean-field solutions with other, more accurate, mean-field approximations (e.g., density-functional calculations), hence stimulating the development of large-scale computational algorithms for modeling radiation damage effects in magnetic alloys and steels.

  19. Final Report for Dynamic Models for Causal Analysis of Panel Data. Models for Change in Quantitative Variables, Part I Deterministic Models. Part II, Chapter 3.

    ERIC Educational Resources Information Center

    Hannan, Michael T.

    This document is part of a series of chapters described in SO 011 759. Addressing the question of effective models to measure change and the change process, the author suggests that linear structural equation systems may be viewed as steady state outcomes of continuous-change models and have rich sociological grounding. Two interpretations of the…

  20. Bacterial Pu(V) reduction in the absence and presence of Fe(III)-NTA: modeling and experimental approach.

    PubMed

    Deo, Randhir P; Rittmann, Bruce E; Reed, Donald T

    2011-09-01

    Plutonium (Pu), a key contaminant at sites associated with the manufacture of nuclear weapons and with nuclear-energy wastes, can be precipitated to "immobilized" plutonium phases in systems that promote bioreduction. Ferric iron (Fe(3+)) is often present in contaminated sites, and its bioreduction to ferrous iron (Fe(2+)) may be involved in the reduction of Pu to forms that precipitate. Alternately, Pu can be reduced directly by the bacteria. Besides Fe, contaminated sites often contain strong complexing ligands, such as nitrilotriacetic acid (NTA). We used biogeochemical modeling to interpret the experimental fate of Pu in the absence and presence of ferric iron (Fe(3+)) and NTA under anaerobic conditions. In all cases, Shewanella alga BrY (S. alga) reduced Pu(V)(PuO(2) (+)) to Pu(III), and experimental evidence indicates that Pu(III) precipitated as PuPO(4(am).) In the absence of Fe(3+) and NTA, reduction of PuO(2) (+) was directly biotic, but modeling simulations support that PuO(2) (+) reduction in the presence of Fe(3+) and NTA was due to an abiotic stepwise reduction of PuO(2) (+) to Pu(4+), followed by reduction of Pu(4+) to Pu(3+), both through biogenically produced Fe(2+). This means that PuO(2) (+) reduction was slowed by first having Fe(3+) reduced to Fe(2+). Modeling results also show that the degree of PuPO(4(am)) precipitation depends on the NTA concentration. While precipitation out-competes complexation when NTA is present at the same or lower concentration than Pu, excess NTA can prevent precipitation of PuPO(4(am)). PMID:21234648

  1. Probabilistic Voxel-Fe model for single cell motility in 3D

    PubMed Central

    Borau, Carlos; Polacheck, William J; Kamm, Roger D; García-Aznar, José Manuel

    2015-01-01

    Background Cells respond to a variety of external stimuli regulated by the environment conditions. Mechanical, chemical and biological factors are of great interest and have been deeply studied. Furthermore, mathematical and computational models have been rapidly growing over the past few years, permitting researches to run complex scenarios saving time and resources. Usually these models focus on specific features of cell migration, making them only suitable to study restricted phenomena. Methods Here we present a versatile finite element (FE) cell-scale 3D migration model based on probabilities depending in turn on ECM mechanical properties, chemical, fluid and boundary conditions. Results With this approach we are able to capture important outcomes of cell migration such as: velocities, trajectories, cell shape and aspect ratio, cell stress or ECM displacements. Conclusions The modular form of the model will allow us to constantly update and redefine it as advancements are made in clarifying how cellular events take place. PMID:26290806

  2. Synthesis and photo-catalytic H2 evolution of three novel biomimetic photocatalysts based on [FeFe]-Hases model compound

    NASA Astrophysics Data System (ADS)

    Zheng, Hui-Qin; Rao, Heng; Wang, Jun; Fan, Yao-Ting; Hou, Hong-Wei

    2015-01-01

    Three new biomimetic photocatalyts based on [2Fe2S]-Hases model compound, namely {(μ-pdte) [Fe(CO)3][Fe(CO)2L], μ-pdte = μ2-S(CH2)2CH[(CH2)3COOCH3]S-μ2, L = CO(1), L = PPh3(2)}, (μ-pdte) [Fe(CO)3] [Fe(CO) (phen)] (3), have been synthesized and characterized by elemental analysis, spectroscopy and particularly X-ray crystallography crystal structure analysis for 1. Visible-light-driven H2 evolution catalyzed by 1-3 in the presence of EY2- as PS, and TEA as electron donor, the maximum H2 yield of 136.2 μmol(17 TON vs. catalyst 2) is detected at pH 11 with 2 of 4 × 10-4 M, EY2- of 4 × 10-4 M, TEA of 10% (v:v) in CH3CN/H2O (v:v,1:1) after 4.5 h irradiation. After that, the effect of the substituent species of catalyst on H2 evolution, the stability of photo-catalytic system and the probable H2 evolution mechanism are also carefully discussed by CV, fluorescence quenching, fluorescence lifetime et al. The result illustrates 2 has been found to be a potential catalyst for conversion of solar energy to clean hydrogen energy under visible light-driven despite that the H2 evolution activity is not high enough in this stage.

  3. Model of Electronic Structure and Superconductivity in Orbitally Ordered FeSe

    NASA Astrophysics Data System (ADS)

    Mukherjee, Shantanu; Kreisel, A.; Hirschfeld, P. J.; Andersen, Brian M.

    2015-07-01

    We provide a band structure with low-energy properties consistent with recent photoemission and quantum oscillation measurements on FeSe, assuming mean-field-like site- and/or bond-centered ferro-orbital ordering at the structural transition. We show how the resulting model provides a consistent explanation of the temperature dependence of the measured Knight shift and the spin-relaxation rate. Furthermore, the superconducting gap structure obtained from spin-fluctuation theory exhibits nodes on the electron pockets, consistent with the V -shaped density of states obtained by tunneling spectroscopy on this material, and the temperature dependence of the London penetration depth.

  4. Two-Part Factor Mixture Modeling: Application to an Aggressive Behavior Measurement Instrument

    ERIC Educational Resources Information Center

    Kim, YoungKoung; Muthen, Bengt O.

    2009-01-01

    This study introduces a two-part factor mixture model as an alternative analysis approach to modeling data where strong floor effects and unobserved population heterogeneity exist in the measured items. As the names suggests, a two-part factor mixture model combines a two-part model, which addresses the problem of strong floor effects by…

  5. Modeling of field- and time-dependent resistance change phenomena under electrical stresses in Fe-O films

    NASA Astrophysics Data System (ADS)

    Eriguchi, Koji; Wei, Zhiqiang; Takagi, Takeshi; Ono, Kouichi

    2010-01-01

    An electrical stress-induced resistance change in an Fe-O film was studied in detail. Under constant voltage stress (CVS) and constant current injection, the resistance of the Fe-O film abruptly increased. The observed time-to-resistance increase (tr) was found to depend on the applied voltage as well as on the injected current density. The total input energy until tr also depended on the applied voltage. From these observations, the mechanisms of resistance change are considered to obey a field-enhanced reaction, and this resistance increase is attributed to a high-resistive Fe-O layer formation at the interface between the anode electrode and the low-resistive Fe-O layer. We proposed a simplified two-step model for the time evolution of the current under CVS [ICVS(t)]. The predicted ICVS(t) showed a good agreement with experimental results. The model also explained the field dependence of tr.

  6. 31 CFR Appendix A to Part 132 - Model Notice

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... U.S. Code of Federal Regulations (12 CFR part 233) and part 132 of title 31 of the U.S. Code of Federal Regulations (31 CFR part 132). ... THE TREASURY PROHIBITION ON FUNDING OF UNLAWFUL INTERNET GAMBLING Pt. 132, App. A Appendix A to...

  7. Radiative transfer modeling for quantifying lunar surface minerals, particle size, and submicroscopic metallic Fe

    NASA Astrophysics Data System (ADS)

    Li, Shuai; Li, Lin

    2011-09-01

    The main objective of this work is to quantify lunar surface minerals (agglutinate, clinopyroxene, orthopyroxene, plagioclase, olivine, ilmenite, and volcanic glass), particle sizes, and the abundance of submicroscopic metallic Fe (SMFe) from the Lunar Soil Characterization Consortium (LSCC) data set with Hapke's radiative transfer theory. The mode is implemented for both forward and inverse modeling. We implement Hapke's radiative transfer theory in the inverse mode in which, instead of commonly used look-up tables, Newton's method and least squares are jointly used to solve nonlinear questions. Although the effects of temperature and surface roughness are incorporated into the implementation to improve the model performance for application of lunar spacecraft data, these effects cannot be extensively addressed in the current work because of the use of lab-measured reflectance data. Our forward radiative transfer model results show that the correlation coefficients between modeled and measured spectra are over 0.99. For the inverse model, the distribution of the particle sizes is all within their measured range. The range of modeled SMFe for highland samples is 0.01%-0.5%, and for mare samples it is 0.03%-1%. The linear trend between SMFe and ferromagnetic resonance (Is) for all the LSCC samples is consistent with laboratory measurements. For quantifying lunar mineral abundances, the results show that the R squared for the training samples (Is/FeO ≤ 65) are over 0.65 with plagioclase having highest correlation (0.94) and pyroxene having the lowest correlation (0.68). In future work, the model needs to be improved for handling more mature lunar soil samples.

  8. Computer Based Learning in FE. A Staff Development Model. A Staff Development Publication.

    ERIC Educational Resources Information Center

    Further Education Unit, London (England).

    This booklet describes the development and content of a model staff development pack for use in training teachers to incorporate the techniques of computer-based learning into their subject teaching. The guide consists of three parts. Part 1 outlines the aims and objectives, content, and use of the pack. Described next are seven curriculum samples…

  9. Thermal aging modeling and validation on the Mo containing Fe-Cr-Ni alloys

    SciTech Connect

    Yang, Ying; Tan, Lizhen; Busby, Jeremy T.

    2015-04-01

    Thermodynamics of intermetallic phases in Fe-rich Fe-Cr-Ni-Mo alloys is critical knowledge to understand thermal aging effect on the phase stability of Mo-containing austenitic steels, which subsequently facilitates alloy design/improvement and degradation mitigation of these materials for reactor applications. Among the intermetallic phases, Chi (χ), Laves, and Sigma (σ) are often of concern because of their tendency to cause embrittlement of the materials. The focus of this study is thermal stability of the Chi and Laves phases as they were less studied compared to the Sigma phase. Coupled with thermodynamic modeling, thermal stability of intermetallic phases in Mo containing Fe-Cr-Ni alloys was investigated at 1000, 850 and 700 C for different annealing times. The morphologies, compositions and crystal structures of the precipitates of the intermetallic phases were carefully examined by scanning electron microscopy, electron probe microanalysis, X-ray diffraction, and transmission electron microscopy. Three key findings resulted from this study. First, the Chi phase is stable at high temperature, and with decreasing temperature it transforms into the Laves phase that is stable at low temperature. Secondly, Cr, Mo, Ni are soluble in both the Chi and Laves phases, with the solubility of Mo playing a major role in the relative stability of the intermetallic phases. Thirdly, in situ transformation from Chi phase to Laves phase was directly observed, which increased the local strain field, generated dislocations in the intermetallic phases, and altered the precipitate phase orientation relationship with the austenitic matrix. The thermodynamic models that were developed and validated were then applied to evaluating the effect of Mo on the thermal stability of intermetallic phases in type 316 and NF709 stainless steels.

  10. State-of-health estimation of LiFePO4/graphite batteries based on a model using differential capacity

    NASA Astrophysics Data System (ADS)

    Torai, Soichiro; Nakagomi, Masaru; Yoshitake, Satoshi; Yamaguchi, Shuichiro; Oyama, Noboru

    2016-02-01

    A model for expressing the differential capacity characteristics of the LiFePO4 (LFP)/graphite battery for the state-of-health (SOH) estimation was proposed. Our model was based on the deformed pseudo-Voigt peak function with several parameters which are directly associated with the phase transition behavior of the active LFP and graphite materials. Charge/discharge cycle tests for accelerated battery fading were performed under a constant high-temperature condition (40 and 45 °C). The SOH estimation was carried out at different fading point of the battery using a part of the responses for the differential capacity versus voltage (dQ/dV vs. V) against the charging process at the rate of C/5 under constant temperature of 25 °C. The changes in the variables of the model with cycling were correlated to the generally mentioned phenomena that the main factors determining the capacity fading of the LFP/graphite battery are the loss of Li+ by a side reaction and that of the active electrode materials. In addition, the robustness related to the charge/discharge history was confirmed, since the memory effect of the LFP/graphite battery, being induced by the previous condition for use, has an influence on the dQ/dV vs. V. The evaluated SOH errors were within ±3%.

  11. Modelling household finances: A Bayesian approach to a multivariate two-part model

    PubMed Central

    Brown, Sarah; Ghosh, Pulak; Su, Li; Taylor, Karl

    2016-01-01

    We contribute to the empirical literature on household finances by introducing a Bayesian multivariate two-part model, which has been developed to further our understanding of household finances. Our flexible approach allows for the potential interdependence between the holding of assets and liabilities at the household level and also encompasses a two-part process to allow for differences in the influences on asset or liability holding and on the respective amounts held. Furthermore, the framework is dynamic in order to allow for persistence in household finances over time. Our findings endorse the joint modelling approach and provide evidence supporting the importance of dynamics. In addition, we find that certain independent variables exert different influences on the binary and continuous parts of the model thereby highlighting the flexibility of our framework and revealing a detailed picture of the nature of household finances. PMID:27212801

  12. Lithium deintercalation in LiFePO4 nanoparticles via a domino-cascade model

    NASA Astrophysics Data System (ADS)

    Delmas, C.; Maccario, M.; Croguennec, L.; Le Cras, F.; Weill, F.

    2008-08-01

    Lithium iron phosphate is one of the most promising positive-electrode materials for the next generation of lithium-ion batteries that will be used in electric and plug-in hybrid vehicles. Lithium deintercalation (intercalation) proceeds through a two-phase reaction between compositions very close to LiFePO4 and FePO4. As both endmember phases are very poor ionic and electronic conductors, it is difficult to understand the intercalation mechanism at the microscopic scale. Here, we report a characterization of electrochemically deintercalated nanomaterials by X-ray diffraction and electron microscopy that shows the coexistence of fully intercalated and fully deintercalated individual particles. This result indicates that the growth reaction is considerably faster than its nucleation. The reaction mechanism is described by a `domino-cascade model' and is explained by the existence of structural constraints occurring just at the reaction interface: the minimization of the elastic energy enhances the deintercalation (intercalation) process that occurs as a wave moving through the entire crystal. This model opens new perspectives in the search for new electrode materials even with poor ionic and electronic conductivities.

  13. Lithium deintercalation in LiFePO4 nanoparticles via a domino-cascade model.

    PubMed

    Delmas, C; Maccario, M; Croguennec, L; Le Cras, F; Weill, F

    2008-08-01

    Lithium iron phosphate is one of the most promising positive-electrode materials for the next generation of lithium-ion batteries that will be used in electric and plug-in hybrid vehicles. Lithium deintercalation (intercalation) proceeds through a two-phase reaction between compositions very close to LiFePO(4) and FePO(4). As both endmember phases are very poor ionic and electronic conductors, it is difficult to understand the intercalation mechanism at the microscopic scale. Here, we report a characterization of electrochemically deintercalated nanomaterials by X-ray diffraction and electron microscopy that shows the coexistence of fully intercalated and fully deintercalated individual particles. This result indicates that the growth reaction is considerably faster than its nucleation. The reaction mechanism is described by a 'domino-cascade model' and is explained by the existence of structural constraints occurring just at the reaction interface: the minimization of the elastic energy enhances the deintercalation (intercalation) process that occurs as a wave moving through the entire crystal. This model opens new perspectives in the search for new electrode materials even with poor ionic and electronic conductivities. PMID:18641656

  14. Integrated research in constitutive modelling at elevated temperatures, part 2

    NASA Technical Reports Server (NTRS)

    Haisler, W. E.; Allen, D. H.

    1986-01-01

    Four current viscoplastic models are compared experimentally with Inconel 718 at 1100 F. A series of tests were performed to create a sufficient data base from which to evaluate material constants. The models used include Bodner's anisotropic model; Krieg, Swearengen, and Rhode's model; Schmidt and Miller's model; and Walker's exponential model.

  15. Phase chemistry and precipitation reactions in maraging steels: Part 3. Model alloys

    SciTech Connect

    Sha, W. .Department of Materials Science and Metallurgy); Cerezo, A.; Smith, G.D.W. . Department of Materials)

    1993-06-01

    This article describes studies of phase transformations during aging in a variety of model maraging steels. Atom-probe field-ion microscopy (APFIM) was the main research technique employed. Thermochemical calculation was also used during the course of the work. The composition and morphology of precipitates were compared in several maraging systems aged at different temperatures for different times to investigate the aging sequence. The APFIM results are compared with studies by other workers using different experimental techniques. In Fe-Ni(-Co)-Mo model alloys, [omega] phase and Fe[sub 7]Mo[sub 6] [mu] phase have been found to contribute to age hardening at different stages of aging; no evidence was found for the existence of Mo-rich clusters in the as-quenched Fe-Ni-Co-Mo alloy. In a high-Si Cr-containing steel, Ti[sub 6]Si[sub 7]Ni[sub 16]G phase and Ni[sub 3]Ti have been found to contribute to age hardening; reverted austenite was found after aging for 5 hours at 520 [degree]C. In a Mn-containing steel, Fe[sub 2]Mo Laves phase and a structurally uncertain phase with a composition of Fe[sub 45]Mn[sub 32]Co[sub 5]Mo[sub 19] have been found to contribute to age hardening.

  16. 12 CFR Appendix A to Part 40 - Model Privacy Form

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... under this part, must comply with section 624 of the FCRA and 12 CFR part 41, subpart C, with respect to... shares. All institutions must use the term “Social Security number” in the first bullet. (2) Institutions...)(2) or C.2(d)(3) of these Instructions. (2) For our marketing purposes. This reason...

  17. Development and Validation of a High Anatomical Fidelity FE Model for the Buttock and Thigh of a Seated Individual.

    PubMed

    Al-Dirini, Rami M A; Reed, Matthew P; Hu, Jingwen; Thewlis, Dominic

    2016-09-01

    Current practices for designing new cushions for seats depend on superficial measurements, such as pressure mapping, which do not provide sufficient information about the condition of sub-dermal tissues. Finite element (FE) modelling offers a unique alternative to integrate assessment of sub-dermal tissue condition into seat/cushion design and development processes. However, the development and validation of such FE models for seated humans requires accurate representation of the anatomy and material properties, which remain challenges that are yet to be addressed. This paper presents the development and validation of a detailed 3D FE model with high anatomical fidelity of the buttock and thigh, for a specific seated subject. The developed model consisted of 28 muscles, the pelvis, sacrum, femur, and one layer of inter-muscular fat, subcutaneous fat and skin. Validation against in vivo measurements from MRI data confirmed that the FE model can simulate the deformation of soft tissues under sitting loads with an accuracy of (mean ± SD) 4.7 ± 4.4 mm. Simulation results showed that the maximum strains (compressive, shear and von-Mises) on muscles (41, 110, 79%) were higher than fat tissues (21, 62, 41%). The muscles that experienced the highest mechanical loads were the gluteus maximus, adductor magnus and muscles in the posterior aspect of the thighs (biceps femoris, semitendinosus and semimembranosus muscles). The developed FE model contributes to the progression towards bio-fidelity in modelling the human body in seated postures by providing insight into the distribution of stresses/strains in individual muscles and inter-muscular fat in the buttock and thigh of seated individuals. Industrial applications for the developed FE model include improving the design of office and household furniture, automotive and airplane seats and wheelchairs as well as customisation and assessment of sporting and medical equipment to meet individual requirements. PMID:26857008

  18. FE Simulation Models for Hot Stamping an Automobile Component with Tailor-Welded High-Strength Steels

    NASA Astrophysics Data System (ADS)

    Tang, Bingtao; Wang, Qiaoling; Wei, Zhaohui; Meng, Xianju; Yuan, Zhengjun

    2016-05-01

    Ultra-high-strength in sheet metal parts can be achieved with hot stamping process. To improve the crash performance and save vehicle weight, it is necessary to produce components with tailored properties. The use of tailor-welded high-strength steel is a relatively new hot stamping process for saving weight and obtaining desired local stiffness and crash performance. The simulation of hot stamping boron steel, especially tailor-welded blanks (TWBs) stamping, is more complex and challenging. Information about thermal/mechanical properties of tools and sheet materials, heat transfer, and friction between the deforming material and the tools is required in detail. In this study, the boron-manganese steel B1500HS and high-strength low-alloy steel B340LA are tailor welded and hot stamped. In order to precisely simulate the hot stamping process, modeling and simulation of hot stamping tailor-welded high-strength steels, including phase transformation modeling, thermal modeling, and thermal-mechanical modeling, is investigated. Meanwhile, the welding zone of tailor-welded blanks should be sufficiently accurate to describe thermal, mechanical, and metallurgical parameters. FE simulation model using TWBs with the thickness combination of 1.6 mm boron steel and 1.2 mm low-alloy steel is established. In order to evaluate the mechanical properties of the hot stamped automotive component (mini b-pillar), hardness and microstructure at each region are investigated. The comparisons between simulated results and experimental observations show the reliability of thermo-mechanical and metallurgical modeling strategies of TWBs hot stamping process.

  19. ALTERATIONS OF FE HOMEOSTASIS IN RAT CARDIOVASCULAR DISEASE MODELS AND ITS CONTRIBUTION TO CARDIOPULMONARY TOXICITY

    EPA Science Inventory

    Introduction: Fe homeostasis can be disrupted in human cardiovascular diseases (CVD). We addressed how dysregulation of Fe homeostasis affected the pulmonary inflammation/oxidative stress response and disease progression after exposure to Libby amphibole (LA), an asbestifonn mine...

  20. HIERARCHICAL METHODOLOGY FOR MODELING HYDROGEN STORAGE SYSTEMS PART II: DETAILED MODELS

    SciTech Connect

    Hardy, B; Donald L. Anton, D

    2008-12-22

    There is significant interest in hydrogen storage systems that employ a media which either adsorbs, absorbs or reacts with hydrogen in a nearly reversible manner. In any media based storage system the rate of hydrogen uptake and the system capacity is governed by a number of complex, coupled physical processes. To design and evaluate such storage systems, a comprehensive methodology was developed, consisting of a hierarchical sequence of models that range from scoping calculations to numerical models that couple reaction kinetics with heat and mass transfer for both the hydrogen charging and discharging phases. The scoping models were presented in Part I [1] of this two part series of papers. This paper describes a detailed numerical model that integrates the phenomena occurring when hydrogen is charged and discharged. A specific application of the methodology is made to a system using NaAlH{sub 4} as the storage media.

  1. Final Report for Dynamic Models for Causal Analysis of Panel Data. Models for Change in Quantitative Variables, Part II Scholastic Models. Part II, Chapter 4.

    ERIC Educational Resources Information Center

    Hannan, Michael T.

    This document is part of a series of chapters described in SO 011 759. Stochastic models for the sociological analysis of change and the change process in quantitative variables are presented. The author lays groundwork for the statistical treatment of simple stochastic differential equations (SDEs) and discusses some of the continuities of…

  2. HIERARCHICAL METHODOLOGY FOR MODELING HYDROGEN STORAGE SYSTEMS. PART I: SCOPING MODELS

    SciTech Connect

    Hardy, B; Donald L. Anton, D

    2008-12-22

    Detailed models for hydrogen storage systems provide essential design information about flow and temperature distributions, as well as, the utilization of a hydrogen storage media. However, before constructing a detailed model it is necessary to know the geometry and length scales of the system, along with its heat transfer requirements, which depend on the limiting reaction kinetics. More fundamentally, before committing significant time and resources to the development of a detailed model, it is necessary to know whether a conceptual storage system design is viable. For this reason, a hierarchical system of models progressing from scoping models to detailed analyses was developed. This paper, which discusses the scoping models, is the first in a two part series that presents a collection of hierarchical models for the design and evaluation of hydrogen storage systems.

  3. Effect of Bridgehead Steric Bulk on the Intramolecular C-H Heterolysis of [FeFe]-Hydrogenase Active Site Models Containing a P2N2 Pendant Amine Ligand.

    PubMed

    Zheng, Dehua; Wang, Mei; Wang, Ning; Cheng, Minglun; Sun, Licheng

    2016-01-19

    A series of pendant amine-containing [FeFe]-hydrogenase models, [X(CH2S-μ)2{Fe(CO)3}{Fe(CO)(P2(Ph)N2(Bn))}] (1H, X = CH2; 2Me, C(CH3)2; 3Et, C(CH2CH3)2; and P2(Ph)N2(Bn) = 1,5-dibenzyl-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane) with different groups at the bridgehead carbon of the S-to-S linker were synthesized. The oxidations of these complexes as well as the reverse reduction reaction were studied by cyclic voltammetry and in situ IR spectroscopy. Regardless of the bridgehead steric bulk, all three complexes demonstrate intramolecular iron-mediated C(sp(3))-H bond heterolytic cleavage with the assistance of the pendant amine base within the chelating diphosphine ligand in the two-electron oxidation process. X-ray crystallographic analysis shows that the doubly oxidized products, [1'H](+), [2'Me](+), and [3'Et](+), all have a rigid FeSC three-membered ring at the open apical site of the rotated iron center. The most noticeable difference in structures of the oxidized complexes is that the single CO ligand of the rotated Fe(P2(Ph)N2(Bn))(CO) unit in [1'H](+) and [2'Me](+) is found below the Fe···Fe vector, while in [3'Et](+) an unusually rotated Fe(P2(Ph)N2(Bn))(CO) moiety positions one of the P donors within the bidentate ligand under the Fe···Fe vector. The starting Fe(I)Fe(I) complexes can be recovered from their corresponding doubly oxidized complexes by reduction in the presence of Brönsted acid. PMID:26230977

  4. Functional model for the [Fe] hydrogenase inspired by the frustrated Lewis pair concept.

    PubMed

    Kalz, Kai F; Brinkmeier, Alexander; Dechert, Sebastian; Mata, Ricardo A; Meyer, Franc

    2014-11-26

    serve as a hydride acceptor. This unprecedented functional model for the [Fe] hydrogenase, using a Lewis acidic imidazolinium salt as a biomimetic hydride acceptor in combination with an organometallic Lewis base, may provide new inspiration for biomimetic H2 activation. PMID:25353322

  5. Modeling the magnetic structure of Dy7Fe3 metallic glass

    NASA Astrophysics Data System (ADS)

    Karlsson, L.; Wannberg, A.; McGreevy, R. L.; Keen, D. A.

    2000-01-01

    Neutron diffraction measurements have been made on amorphous Dy7Fe3 at 13 temperatures between 10 and 300 K. The data have been modeled using the reverse Monte Carlo method under the assumption that the atomic structure is isomorphous with that of Dy7Ni3 [D. A. Keen and R. L. McGreevy, J. Phys. Condens. Matter 2, 7383 (1991)]. From the resulting configurations we find that the near-neighbor ordering is ferromagnetic, but the spin-spin correlation is strongly oscillatory. We also find that there is no strong radial component in the spin-spin correlations; this has previously been shown for Dy7-xYxNi3 glasses [D. A. Keen, R. L. McGreevy, R. I. Bewley, and R. Cywinski, Nucl. Instrum. Methods Phys. Res. A 354, 48 (1995); D. A. Keen, R. I. Bewley, R. Cywinski, and R. L. McGreevy, Phys. Rev. B 54, 1036 (1996)]. By integrating the first peak in the spin-spin correlation function and taking it as a function of temperature, we find a clear point of inflexion at 80 K. This signifies the ordering temperature, in good agreement with susceptibility measurements. Since this curve is derived from the near-neighbor ordering the result shows that the material orders magnetically on all length scales at the same temperature; this is quite distinct from the type of domain ordering observed in, e.g., Fe1-xBx glasses.

  6. Synthetic Models for the [FeFe]-Hydrogenase: Catalytic Proton Reduction and the Structure of the Doubly Protonated Intermediate

    PubMed Central

    Carroll, Maria E.; Barton, Bryan E.; Rauchfuss, Thomas B.; Carroll, Patrick J.

    2012-01-01

    This report compares biomimetic HER catalysts with and without the amine cofactor (adtNH): Fe2(adtNH)(CO)2(dppv)2 (1NH) and Fe2(pdt)(CO)2(dppv)2 (2; (adtNH)2− = (HN(CH2S)22−, pdt2− = 1,3-(CH2)3S22−). These compounds are spectroscopically, structurally, and stereodynamically very similar but exhibit very different catalytic properties. Protonation of 1NH and 2 each give three isomeric hydrides beginning with the kinetically favored terminal hydride, which converts sequentially to sym and unsym isomers of the bridging hydrides. In the case of the amine, the corresponding ammonium-hydrides are also observed. In the case of the terminal amine hydride [t-H1NH]BF4, the ammonium/amine-hydride equilibrium is sensitive to counteranions and solvent. The species [t-H1NH2](BF4)2 represents the first example of a crystallographically characterized terminal hydride produced by protonation. The NH--HFe distance of 1.88(7) Å indicates dihydrogen bonding. The bridging hydrides [µ-H1NH]+ and [µ-H2]+ reduce near −1.8 V, about 150 mV more negative than the reductions of the terminal hydride [t-H1NH]+ and [t-H2]+ at −1.65 V. Reductions of the amine hydrides [t-H1NH]+ and [t-H1NH2]2+ are irreversible. For the pdt analog, the [t-H2]+/0 couple is unaffected by weak acids (pKaMeCN 15.3) but exhibits catalysis with HBF4•Et2O, albeit with a TOF around 4 s−1 and an overpotential greater than 1 V. The voltammetry of [t-H1NH]+ is strongly affected by relatively weak acids and proceeds at 5000 s−1 with an overpotential of 0.7 V. The ammonium-hydride [t-H1NH2]2+ is a faster catalyst with an estimated TOF of 58,000 s−1 and an overpotential of 0.5 V. PMID:23126330

  7. Hydrothermal Fe cycling and deep ocean organic carbon scavenging: Model-based evidence for significant POC supply to seafloor sediments

    NASA Astrophysics Data System (ADS)

    German, C. R.; Legendre, L. L.; Sander, S. G.; Niquil, N.; Luther, G. W.; Bharati, L.; Han, X.; Le Bris, N.

    2015-06-01

    Submarine hydrothermal venting has recently been identified to have the potential to impact ocean biogeochemistry at the global scale. This is the case because processes active in hydrothermal plumes are so vigorous that the residence time of the ocean, with respect to cycling through hydrothermal plumes, is comparable to that of deep ocean mixing caused by thermohaline circulation. Recently, it has been argued that seafloor venting may provide a significant source of bio-essential Fe to the oceans as the result of a close coupling between Fe and organic carbon in hydrothermal plumes. But a complementary question remains to be addressed: does this same intimate Fe-Corg association in hydrothermal plumes cause any related impact to the global C cycle? To address this, SCOR-InterRidge Working Group 135 developed a modeling approach to synthesize site-specific field data from the East Pacific Rise 9°50‧ N hydrothermal field, where the range of requisite data sets is most complete, and combine those inputs with global estimates for dissolved Fe inputs from venting to the oceans to establish a coherent model with which to investigate hydrothermal Corg cycling. The results place new constraints on submarine Fe vent fluxes worldwide, including an indication that the majority of Fe supplied to hydrothermal plumes should come from entrainment of diffuse flow. While this same entrainment is not predicted to enhance the supply of dissolved organic carbon to hydrothermal plumes by more than ∼10% over background values, what the model does indicate is that scavenging of carbon in association with Fe-rich hydrothermal plume particles should play a significant role in the delivery of particulate organic carbon to deep ocean sediments, worldwide.

  8. In search of metal hydrides: an X-ray absorption and emission study of [NiFe] hydrogenase model complexes.

    PubMed

    Hugenbruch, Stefan; Shafaat, Hannah S; Krämer, Tobias; Delgado-Jaime, Mario Ulises; Weber, Katharina; Neese, Frank; Lubitz, Wolfgang; DeBeer, Serena

    2016-04-28

    Metal hydrides are invoked as important intermediates in both chemical and biological H2 production. In the [NiFe] hydrogenase enzymes, pulsed EPR and high-resolution crystallography have argued that the hydride interacts primarily at the Ni site. In contrast, in [NiFe] hydrogenase model complexes, it is observed that the bridging hydride interacts primarily with the Fe. Herein, we utilize a combination of Ni and Fe X-ray absorption (XAS) and emission (XES) spectroscopies to examine the contribution of the bridging hydride to the observed spectral features in [(dppe)Ni(μ-pdt)(μ-H)Fe(CO)3](+). The corresponding data on (dppe)Ni(μ-pdt)Fe(CO)3 are used as a reference for the changes that occur in the absence of a hydride bridge. For further interpretation of the observed spectral features, all experimental spectra were calculated using a density functional theory (DFT) approach, with excellent agreement between theory and experiment. It is found that the iron valence-to-core (VtC) XES spectra reveal clear signatures for the presence of a Fe-H interaction in the hydride bridged model complex. In contrast, the Ni VtC XES spectrum largely reflects changes in the local Ni geometry and shows little contribution from a Ni-H interaction. A stepwise theoretical analysis of the hydride contribution and the Ni site symmetry provides insights into the factors, which govern the different metal-hydride interactions in both the model complexes and the enzyme. Furthermore, these results establish the utility of two-color XES to reveal important insights into the electronic structure of various metal-hydride species. PMID:26924248

  9. Integrated research in constitutive modelling at elevated temperatures, part 1

    NASA Technical Reports Server (NTRS)

    Haisler, W. E.; Allen, D. H.

    1986-01-01

    Topics covered include: numerical integration techniques; thermodynamics and internal state variables; experimental lab development; comparison of models at room temperature; comparison of models at elevated temperature; and integrated software development.

  10. DIETARY EXPOSURES OF YOUNG CHILDREN, PART 3: MODELLING

    EPA Science Inventory

    A deterministic model was used to model dietary exposure of young children. Parameters included pesticide residue on food before handling, surface pesticide loading, transfer efficiencies and children's activity patterns. Three components of dietary pesticide exposure were includ...

  11. REVIEW OF INDOOR EMISSION SOURCE MODELS--PART 1. OVERVIEW

    EPA Science Inventory

    Indoor emission source models are mainly used as a component in indoor air quality (IAQ) and exposure modeling. They are also widely used to interpret the experimental data obtained from environmental chambers and buildings. This paper compiles 46 indoor emission source models fo...

  12. Atomic kinetic Monte Carlo modeling of multi-component Fe dilute alloys under irradiation

    NASA Astrophysics Data System (ADS)

    Domain, C.; Becquart, C. S.

    2014-06-01

    The ageing of pressure vessel steels under radiation has been correlated with the formation of more or less dilute solute clusters which are investigated in this work using a multiscale approach based on ab initio and atomistic kinetic Monte Carlo (AKMC) simulations. The microstructure evolution of Fe alloys is modeled by AKMC on a lattice, using pair interactions adjusted on DFT calculations. Several substitutional elements (Cu, Ni, Mn, Si, P) and foreign interstitials (C, N) are taken into account to describe the alloy. The point defect created by the irradiation, i.e. the vacancies and self interstitials have a tendency to form clusters. The evolution of these clusters is governed by the migration energy of the individual point defects which is very heavy in terms of computing time due to the large number of AKMC steps required. The structure of all the possible objects that can form is complex and some optimized and accelerated methods will be presented.

  13. Occupant kinematics and estimated effectiveness of side airbags in pole side impacts using a human FE model with internal organs.

    PubMed

    Hayashi, Shigeki; Yasuki, Tsuyoshi; Kitagawa, Yuichi

    2008-11-01

    When a car collides against a pole-like obstacle, the deformation pattern of the vehicle body-side tends to extend to its upper region. A possible consequence is an increase of loading to the occupant thorax. Many studies have been conducted to understand human thoracic responses to lateral loading, and injury criteria have been developed based on the results. However, injury mechanisms, especially those of internal organs, are not well understood. A human body FE model was used in this study to simulate occupant kinematics in a pole side impact. Internal organ parts were introduced into the torso model, including their geometric features, material properties and connections with other tissues. The mechanical responses of the model were validated against PMHS data in the literature. Although injury criterion for each organ has not been established, pressure level and its changes can be estimated from the organ models. Finite element simulations were conducted assuming a case where a passenger vehicle collides against a pole at 29km/h. Occupant kinematics, force-deformation responses and pressure levels were compared between cases with and without side airbag deployment. The results indicated that strain to the ribs and pressure to the organs was smaller with side airbag deployment. The side airbag widened the contact area at the torso, helping to distribute the force to the shoulder, arm and chest. Such distributed force helped generate relatively smaller deformation in the ribs. Furthermore, the side airbag deployment helped restrict the spine displacement. The smaller displacement contributed to lowering the magnitude of contact force between the torso and the door. The study also examined the correlations between the pressure levels in the internal organs, rib deflection, and V*C of chest. The study found that the V*C(t) peak appeared to be synchronized with the organ pressure peak, suggesting that the pressure level of the internal organs could be one possible

  14. Part Time Faculty Staff Development Model for the Nineties.

    ERIC Educational Resources Information Center

    Ostertag, Vesna

    The Central Texas College Europe Campus (CTCEC), in Hanau, Germany, provides associate degrees for American Armed Services personnel stationed in Europe. Between 1980 and 1990, part-time faculty at CTCEC increased from 60% to 80%. In order to meet the training needs of this growing number of adjunct faculty, a Committee for Professional…

  15. 12 CFR Appendix A to Part 332 - Model Privacy Form

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... the FCRA and 12 CFR part 334, subpart C, with respect to the initial notice and opt-out and any... information that the institution collects and shares. All institutions must use the term “Social Security...) For our marketing purposes. This reason incorporates sharing information with service providers by...

  16. 12 CFR Appendix A to Part 216 - Model Privacy Form

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... the FCRA and 12 CFR part 222, subpart C, with respect to the initial notice and opt-out and any... information that the institution collects and shares. All institutions must use the term “Social Security...) For our marketing purposes. This reason incorporates sharing information with service providers by...

  17. Modeling three-dimensional structure of two closely related Ni-Fe hydrogenases.

    PubMed

    Abdullatypov, A V; Tsygankov, A A

    2015-08-01

    The results of homology modeling of HydSL, a NiFe-hydrogenase from purple sulfur bacterium Thiocapsa roseopersicina BBS, and deep-water bacterium Alteromonas macleodii deep ecotype are presented in this work. It is shown that the models have larger confidence level than earlier published ones; full-size models of these enzymes are presented for the first time. The C-end fragment of small subunit of T. roseopersicina hydrogenase is shown to have random orientation in relation to the main protein globule. The obtained models of this enzyme have a large number of ion pairs, as well as thermostable HydSL hydrogenase from Allochromatium vinosum, in contrast to thermostable HydSL hydrogenase from Alt. macleodii and thermolabile HydAB hydrogenase from Desulfovibrio vulgaris. The possible determinant of oxygen stability of studied hydrogenases could be the lack of several intramolecular tunnels. Hydrophobic and electrostatic surfaces were mapped in order to find out possible pathways of coupling hydrogenase to electron-transferring chains, as well as methods for construction of artificial photobiohydrogen-producing systems. PMID:25572109

  18. Modeling specific heat and entropy change in La(Fe-Mn-Si)13-H compounds

    NASA Astrophysics Data System (ADS)

    Piazzi, Marco; Bennati, Cecilia; Curcio, Carmen; Kuepferling, Michaela; Basso, Vittorio

    2016-02-01

    In this paper we model the magnetocaloric effect of LaFexMnySiz-H1.65 compound (x + y + z = 13), a system showing a transition temperature finely tunable around room temperature by Mn substitution. The thermodynamic model takes into account the coupling between magnetism and specific volume as introduced by Bean and Rodbell. We find a good qualitative agreement between experimental and modeled entropy change - Δs(H , T). The main result is that the magnetoelastic coupling drives the phase transition of the system, changing it from second to first order by varying a model parameter η. It is also responsible for a decrease of - Δs at the transition, due to a small lattice contribution to the entropy counteracting the effect of the magnetic one. The role of Mn is reflected exclusively in a decrease of the strength of the exchange interaction, while the value of the coefficient β, responsible for the coupling between volume and exchange energy, is independent on the Mn content and it appears to be an intrinsic property of the La(Fe-Si)13 structure.

  19. A model of Fe speciation and biogeochemistry at the Tropical Eastern North Atlantic Time-Series Observatory site

    NASA Astrophysics Data System (ADS)

    Ye, Y.; Völker, C.; Wolf-Gladrow, D. A.

    2009-10-01

    A one-dimensional model of Fe speciation and biogeochemistry, coupled with the General Ocean Turbulence Model (GOTM) and a NPZD-type ecosystem model, is applied for the Tropical Eastern North Atlantic Time-Series Observatory (TENATSO) site. Among diverse processes affecting Fe speciation, this study is focusing on investigating the role of dust particles in removing dissolved iron (DFe) by a more complex description of particle aggregation and sinking, and explaining the abundance of organic Fe-binding ligands by modelling their origin and fate. The vertical distribution of different particle classes in the model shows high sensitivity to changing aggregation rates. Using the aggregation rates from the sensitivity study in this work, modelled particle fluxes are close to observations, with dust particles dominating near the surface and aggregates deeper in the water column. POC export at 1000 m is a little higher than regional sediment trap measurements, suggesting further improvement of modelling particle aggregation, sinking or remineralisation. Modelled strong ligands have a high abundance near the surface and decline rapidly below the deep chlorophyll maximum, showing qualitative similarity to observations. Without production of strong ligands, phytoplankton concentration falls to 0 within the first 2 years in the model integration, caused by strong Fe-limitation. A nudging of total weak ligands towards a constant value is required for reproducing the observed nutrient-like profiles, assuming a decay time of 7 years for weak ligands. This indicates that weak ligands have a longer decay time and therefore cannot be modelled adequately in a one-dimensional model. The modelled DFe profile is strongly influenced by particle concentration and vertical distribution, because the most important removal of DFe in deeper waters is colloid formation and aggregation. Redissolution of particulate iron is required to reproduce an observed DFe profile at TENATSO site

  20. Probing Bis-Fe(IV) MauG: Experimental Evidence for the Long-Range Charge-Resonance Model

    PubMed Central

    Geng, Jiafeng; Davis, Ian

    2015-01-01

    The biosynthesis of tryptophan tryptophylquinone, a protein-derived cofactor, involves a long-range reaction mediated by a bis-Fe(IV) intermediate of a di-heme enzyme, MauG. Recently, a unique charge-resonance (CR) phenomenon was discovered in this intermediate, and a biological, long-distance CR model was proposed. This model suggests that the chemical nature of the bis-Fe(IV) species is not as simple as it appears; rather, it is composed of a collection of resonance structures in a dynamic equilibrium. Here, we experimentally evaluated the proposed CR model by introducing small molecules to, and measuring the temperature dependence of, bis-Fe(IV) MauG. Spectroscopic evidence was presented to demonstrate that the selected compounds increase the decay rate of the bis-Fe(IV) species via disrupting the equilibrium of the resonance structures that constitutes the proposed CR model. The results support this new CR model and bring a fresh concept to the classical CR theory. PMID:25631460

  1. Modes of interconnected lattice trusses using continuum models, part 1

    NASA Technical Reports Server (NTRS)

    Balakrishnan, A. V.

    1991-01-01

    This represents a continuing systematic attempt to explore the use of continuum models--in contrast to the Finite Element Models currently universally in use--to develop feedback control laws for stability enhancement of structures, particularly large structures, for deployment in space. We shall show that for the control objective, continuum models do offer unique advantages. It must be admitted of course that developing continuum models for arbitrary structures is no easy task. In this paper we take advantage of the special nature of current Large Space Structures--typified by the NASA-LaRC Evolutionary Model which will be our main concern--which consists of interconnected orthogonal lattice trusses each with identical bays. Using an equivalent one-dimensional Timoshenko beam model, we develop an almost complete continuum model for the evolutionary structure. We do this in stages, beginning only with the main bus as flexible and then going on to make all the appendages also flexible-except for the antenna structure. Based on these models we proceed to develop formulas for mode frequencies and shapes. These are shown to be the roots of the determinant of a matrix of small dimension compared with mode calculations using Finite Element Models, even though the matrix involves transcendental functions. The formulas allow us to study asymptotic properties of the modes and how they evolve as we increase the number of bodies which are treated as flexible. The asymptotics, in fact, become simpler.

  2. Bacterial Pu(V) reduction in the absence and presence of Fe(III)-NTA: modeling and experimental approach

    SciTech Connect

    Deo, Randhir P; Rittmann, Bruce E; Reed, Donald T

    2013-01-10

    Plutonium (Pu), a key contaminant at sites associated with the manufacture of nuclear weapons and with nuclear-energy wastes, can be precipitated to 'immobilized' plutonium phases in systems that promote bioreduction. Ferric iron (Fe3+) is often present in contaminated sites, and its bioreduction to ferrous iron (Fe2+) may be involved in the reduction of Pu to forms that precipitate. Alternately, Pu can be reduced directly by the bacteria. Besides Fe, contaminated sites often contain strong complexing ligands, such as nitrilotriacetic acid (NTA). We used biogeochemical modeling to interpret the experimental fate of Pu in the absence and presence of ferric iron (Fe3+) and NTA under anaerobic conditions. In all cases, Shewanella alga BrY (S. alga) reduced Pu(V)(PuO2+) to Pu(III), and experimental evidence indicates that Pu(III) precipitated as PuPO4(am). In the absence of Fe3+ and NTA, reduction of PuO2+ was directly biotic, but modeling simulations support that PuO2+ reduction in the presence of Fe3+ and NTA was due to an abiotic stepwise reduction of PuO2+ to Pu4+, followed by reduction of Pu4+ to Pu3+, both through biogenically produced Fe2+. This means that PuO2+ reduction was slowed by first having Fe3+ reduced to Fe2+. Modeling results also show that the degree of PuPO4(am) precipitation depends on the NTA concentration. While precipitation out-competes complexation when NTA is present at the same or lower concentration than Pu, excess NTA can prevent precipitation of PuPO4(am).

  3. STORM WATER MANAGEMENT MODEL, VERSION 4. PART A: USER'S MANUAL

    EPA Science Inventory

    The EPA Storm Water Management Model (SWMM) is a comprehensive mathematical model for simulation of urban runoff water quality and quantity in storm and combined sewer systems. All aspects of the urban hydrologic and quality cycles are simulated, including surface and subsurface ...

  4. First-principles study of the minimal model of magnetic interactions in Fe-based superconductors

    NASA Astrophysics Data System (ADS)

    Glasbrenner, J. K.; Velev, J. P.; Mazin, I. I.

    2014-02-01

    Using noncollinear first-principles calculations, we perform a systematic study of the magnetic order in several families of ferropnictides. We find a fairly universal energy dependence on the magnetization order in all cases. Our results confirm that a simple Heisenberg model fails to account for the energy dependence of the magnetization in a couple of ways: first, a biquadratic term is present in all cases and, second, the magnetic moment softens depending on the orientation. We also find that hole doping substantially reduces the biquadratic contribution, although the antiferromagnetic stripe state remains stable within the whole range of doping concentrations, and thus the reported lack of the orthorhombicity in Na-doped BaFe2As2 is probably due to factors other than a sign reversal of the biquadratic term. Finally, we discover that even with the biquadratic term, there is a limit to the accuracy of mapping the density functional theory energetics onto Heisenberg-type models, independent of the range of the model.

  5. Conceptual Modeling in the Time of the Revolution: Part II

    NASA Astrophysics Data System (ADS)

    Mylopoulos, John

    Conceptual Modeling was a marginal research topic at the very fringes of Computer Science in the 60s and 70s, when the discipline was dominated by topics focusing on programs, systems and hardware architectures. Over the years, however, the field has moved to centre stage and has come to claim a central role both in Computer Science research and practice in diverse areas, such as Software Engineering, Databases, Information Systems, the Semantic Web, Business Process Management, Service-Oriented Computing, Multi-Agent Systems, Knowledge Management, and more. The transformation was greatly aided by the adoption of standards in modeling languages (e.g., UML), and model-based methodologies (e.g., Model-Driven Architectures) by the Object Management Group (OMG) and other standards organizations. We briefly review the history of the field over the past 40 years, focusing on the evolution of key ideas. We then note some open challenges and report on-going research, covering topics such as the representation of variability in conceptual models, capturing model intentions, and models of laws.

  6. 16 CFR Appendix A to Part 698 - Model Prescreen Opt-Out Notices

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Model Prescreen Opt-Out Notices A Appendix A to Part 698 Commercial Practices FEDERAL TRADE COMMISSION THE FAIR CREDIT REPORTING ACT MODEL FORMS AND DISCLOSURES Pt. 698, App. A Appendix A to Part 698—Model Prescreen Opt-Out Notices In order...

  7. 12 CFR Appendix A to Part 704 - Capital Prioritization and Model Forms

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 7 2012-01-01 2012-01-01 false Capital Prioritization and Model Forms A... UNIONS CORPORATE CREDIT UNIONS Pt. 704, App. A Appendix A to Part 704—Capital Prioritization and Model...) Ensure the credit union uses the appropriate initial and periodic Model Form disclosures in Part II...

  8. 16 CFR Appendix A to Part 698 - Model Prescreen Opt-Out Notices

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 1 2012-01-01 2012-01-01 false Model Prescreen Opt-Out Notices A Appendix A to Part 698 Commercial Practices FEDERAL TRADE COMMISSION THE FAIR CREDIT REPORTING ACT MODEL FORMS AND DISCLOSURES Pt. 698, App. A Appendix A to Part 698—Model Prescreen Opt-Out Notices In order...

  9. 16 CFR Appendix A to Part 698 - Model Prescreen Opt-Out Notices

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Model Prescreen Opt-Out Notices A Appendix A to Part 698 Commercial Practices FEDERAL TRADE COMMISSION THE FAIR CREDIT REPORTING ACT MODEL FORMS AND DISCLOSURES Pt. 698, App. A Appendix A to Part 698—Model Prescreen Opt-Out Notices In order...

  10. 12 CFR Appendix A to Part 704 - Capital Prioritization and Model Forms

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 7 2014-01-01 2014-01-01 false Capital Prioritization and Model Forms A... UNIONS CORPORATE CREDIT UNIONS Pt. 704, App. A Appendix A to Part 704—Capital Prioritization and Model...) Ensure the credit union uses the appropriate initial and periodic Model Form disclosures in Part II...

  11. 12 CFR Appendix A to Part 704 - Capital Prioritization and Model Forms

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 7 2013-01-01 2013-01-01 false Capital Prioritization and Model Forms A... UNIONS CORPORATE CREDIT UNIONS Pt. 704, App. A Appendix A to Part 704—Capital Prioritization and Model...) Ensure the credit union uses the appropriate initial and periodic Model Form disclosures in Part II...

  12. 16 CFR Appendix A to Part 698 - Model Prescreen Opt-Out Notices

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 1 2013-01-01 2013-01-01 false Model Prescreen Opt-Out Notices A Appendix A to Part 698 Commercial Practices FEDERAL TRADE COMMISSION THE FAIR CREDIT REPORTING ACT MODEL FORMS AND DISCLOSURES Pt. 698, App. A Appendix A to Part 698—Model Prescreen Opt-Out Notices In order...

  13. 16 CFR Appendix A to Part 698 - Model Prescreen Opt-Out Notices

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Model Prescreen Opt-Out Notices A Appendix A to Part 698 Commercial Practices FEDERAL TRADE COMMISSION THE FAIR CREDIT REPORTING ACT MODEL FORMS AND DISCLOSURES Pt. 698, App. A Appendix A to Part 698—Model Prescreen Opt-Out Notices In order...

  14. 16 CFR Appendix C to Part 698 - Model Forms for Affiliate Marketing Opt-Out Notices

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 1 2013-01-01 2013-01-01 false Model Forms for Affiliate Marketing Opt-Out Notices C Appendix C to Part 698 Commercial Practices FEDERAL TRADE COMMISSION THE FAIR CREDIT REPORTING ACT MODEL FORMS AND DISCLOSURES Pt. 698, App. C Appendix C to Part 698—Model Forms for...

  15. 16 CFR Appendix C to Part 698 - Model Forms for Affiliate Marketing Opt-Out Notices

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Model Forms for Affiliate Marketing Opt-Out Notices C Appendix C to Part 698 Commercial Practices FEDERAL TRADE COMMISSION THE FAIR CREDIT REPORTING ACT MODEL FORMS AND DISCLOSURES Pt. 698, App. C Appendix C to Part 698—Model Forms for...

  16. 16 CFR Appendix C to Part 698 - Model Forms for Affiliate Marketing Opt-Out Notices

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Model Forms for Affiliate Marketing Opt-Out Notices C Appendix C to Part 698 Commercial Practices FEDERAL TRADE COMMISSION THE FAIR CREDIT REPORTING ACT MODEL FORMS AND DISCLOSURES Pt. 698, App. C Appendix C to Part 698—Model Forms for...

  17. 16 CFR Appendix C to Part 698 - Model Forms for Affiliate Marketing Opt-Out Notices

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 1 2012-01-01 2012-01-01 false Model Forms for Affiliate Marketing Opt-Out Notices C Appendix C to Part 698 Commercial Practices FEDERAL TRADE COMMISSION THE FAIR CREDIT REPORTING ACT MODEL FORMS AND DISCLOSURES Pt. 698, App. C Appendix C to Part 698—Model Forms for...

  18. Agent-based modeling and simulation Part 3 : desktop ABMS.

    SciTech Connect

    Macal, C. M.; North, M. J.; Decision and Information Sciences

    2007-01-01

    Agent-based modeling and simulation (ABMS) is a new approach to modeling systems comprised of autonomous, interacting agents. ABMS promises to have far-reaching effects on the way that businesses use computers to support decision-making and researchers use electronic laboratories to support their research. Some have gone so far as to contend that ABMS 'is a third way of doing science,' in addition to traditional deductive and inductive reasoning (Axelrod 1997b). Computational advances have made possible a growing number of agent-based models across a variety of application domains. Applications range from modeling agent behavior in the stock market, supply chains, and consumer markets, to predicting the spread of epidemics, the threat of bio-warfare, and the factors responsible for the fall of ancient civilizations. This tutorial describes the theoretical and practical foundations of ABMS, identifies toolkits and methods for developing agent models, and illustrates the development of a simple agent-based model of shopper behavior using spreadsheets.

  19. Dimeric Fe (II, III) complex of quinoneoxime as functional model of PAP enzyme: Mössbauer, magneto-structural and DNA cleavage studies

    NASA Astrophysics Data System (ADS)

    Salunke-Gawali, Sunita; Ahmed, Khursheed; Varret, François; Linares, Jorge; Zaware, Santosh; Date, Sadgopal; Rane, Sandhya

    2008-07-01

    Purple acid phosphatase, ( PAP), is known to contain dinuclear Fe2 + 2, + 3 site with characteristic Fe + 3 ← Tyr ligand to metal charge transfer in coordination. Phthiocoloxime (3-methyl-2-hydroxy-1,4-naphthoquinone-1-oxime) ligand L, mimics (His/Tyr) ligation with controlled and unique charge transfers resulting in valence tautomeric coordination with mixed valent diiron site in model compound Fe-1: [μ-OH-Fe2 + 2, + 3 ( o-NQCH3ox) ( o-NSQCH3ox)2 (CAT) H2O]. Fe-2: [Fe + 3( o-NQCH3ox) ( p-NQCH3ox)2]2 a molecularly associated dimer of phthiocoloxime synthesized for comparison of charge transfer. 57Fe Mössbauer studies was used to quantitize unusual valences due to ligand in dimeric Fe-1 and Fe-2 complexes which are supported by EPR and SQUID studies. 57Fe Mössbauer spectra for Fe-1 at 300 K indicates the presence of two quadrupole split asymmetric doublets due to the differences in local coordination geometries of [Fe + 3]A and [Fe + 2]B sites. The hyperfine interaction parameters are δ A = 0.152, (Δ E Q)A = 0.598 mm/s with overlapping doublet at δ B = 0.410 and (Δ E Q)B = 0.468 mm/s. Due to molecular association tendency of ligand, dimer Fe-2 possesses 100% Fe + 3(h.s.) hexacoordinated configuration with isomer shift δ = 0.408 mm/s. Slightly distorted octahedral symmetry created by NQCH3ox ligand surrounding Fe + 3(h.s.) state generates small field gradient indicated by quadrupole split Δ E Q = 0.213 mm/s. Decrease of isomer shifts together with variation of quadrupole splits with temperature in Fe-1 dimer compared to Fe-2 is result of charge transfers in [Fe2 + 2, + 3 SQ] complexes. EPR spectrum of Fe-1 shows two strong signals at g 1 = 4.17 and g 2 = 2.01 indicative of S = 3/2 spin state with an intermediate spin of Fe + 3(h.s.) configuration. SQUID data of χ _m^{corr} .T were best fitted by using HDVV spin pair model S = 2, 3/2 resulting in antiferromagnetic exchange ( J = -13.5 cm - 1 with an agreement factor of R = 1.89 × 10 - 5). The lower J

  20. 59Fe(n,g)60Fe and 60Fe(n,g)61Fe Reaction Rates from Local Systematics

    SciTech Connect

    Kelley, K; Hoffman, R D; Drake, M

    2005-04-25

    We present modeled neutron capture cross sections relevant to stellar production of {sup 60}Fe. Systematics for the input parameters required by the Hauser-Feshbach statistical model are developed based on measured data in the local region of the isotopic plane (20 {le} Z {le} 29, 43 {le} A {le} 65). These parameters and used to calculate reaction cross sections and rates for select target isotopes. Modeled cross sections are compared to experimental data where available. The {sup 59}Fe(n,{gamma}){sup 60}Fe and {sup 60}Fe(n, {gamma}){sup 61}Fe rates are compared to previous calculations. A brief discussion of errors related to the modeling is provided. We conclude by investigating the sensitivity of stellar production of {sup 26}Al and {sup 60}Fe to the {sup 59}Fe(n,{gamma}){sup 60}Fe and {sup 60}Fe(n,{gamma})61Fe reaction rates using a single zone model.

  1. Superposition model calculation of zero-field splitting of Fe3+ in LiTaO3 crystal

    NASA Astrophysics Data System (ADS)

    Yeom, T. H.

    2001-11-01

    The second-order zero-field splitting (ZFS) parameter b20 of the Fe3+ ion centre at the Li site, the Ta site and the structural vacancy site in the LiTaO3 crystal are calculated using the empirical superposition model. The fourth-order ZFS parameters b40, b43 and b4-3 are also calculated at the Li and Ta site, respectively. The calculated b20 of Fe3+ ion at the Li site agrees well with the experimental one. It is concluded that the Fe3+ replaces the Li+ ion rather than the Ta5+ ion in the LiTaO3 crystal. This conclusion confirms the site assignment from the electron nuclear double resonance experiments.

  2. Phenomenological magnetic modeling of Au:Fe:Au nano-onions

    NASA Astrophysics Data System (ADS)

    Wiggins, J.; Carpenter, Everett E.; O'Connor, Charles J.

    2000-05-01

    A new type of materials, the nano-onions, has been shown to exhibit GMR. These nanostructured composites consist of a nonmagnetic core coated with a thin layer of a bulk ferromagnet with a passivating nonmagnetic surface layer. The nano-onion investigated had a 3 nm Au core, a 1 nm Fe layer, and a 2 nm Au coating; all values correspond to the radius. The materials were manufactured using a sequential reverse micelle technique, detailed elsewhere. The sample preparation method produces a powder sample was cold pressed into a pellet. Magnetic investigation of the sample indicated that the material was superparamagnetic with a blocking temperature of 52 K for particles approximately 8 nm in diameter. At 10 K, the coercivity was 420 Oe, indicating a large degree of order. The GMR was measured over the entire temperature range available. At 10 K, in 5 T, a 1% MR was observed. The GMR was modeled using a simple phenomenological magnetic model initially used to study GMR granular thin films. To more accurately match the physical parameters of reverse micelles, the conventional log-normal particle size distribution was replaced with a normal distribution. The model suggested that the system consisted of an ensemble of 1.3 nm particles with a standard deviation of 0.07. The model does not detect the entire 8 nm diam, rather it detects the individual walls of the shell. In this context, it has shown that a simple phenomenological model can accurately predict the magnetic and electronic behavior of nano-onions.

  3. Magnetic model in multiferroic NdFe 3(BO 3)4 investigated by inelastic neutron scattering

    NASA Astrophysics Data System (ADS)

    Hayashida, S.; Soda, M.; Itoh, S.; Yokoo, T.; Ohgushi, K.; Kawana, D.; Rønnow, H. M.; Masuda, T.

    2015-08-01

    We performed inelastic neutron scattering measurements on single crystals of NdFe3(BO113 )4 to explore the magnetic excitations, to establish the underlying Hamiltonian, and to reveal the detailed nature of hybridization between the 4 f and 3 d magnetism. The observed spectra exhibiting a couple of key features, i.e., anticrossing of Nd and Fe excitations and anisotropy gap at the antiferromagnetic zone center, are explained by the magnetic model including spin interaction in the framework of weakly coupled Fe3 + chains, interaction between the Fe3 + and Nd3 + moments, and single-ion anisotropy derived from the Nd3 + crystal field. The combination of the measurements and calculations reveals that the hybridization between 4 f and 3 d magnetism propagates the local magnetic anisotropy of the Nd3 + moment to the Fe3 + network, leading to the determination of the bulk structure of both electric polarization and magnetic moment in the multiferroics of the spin-dependent metal-ligand hybridization type.

  4. Random Predictor Models for Rigorous Uncertainty Quantification: Part 1

    NASA Technical Reports Server (NTRS)

    Crespo, Luis G.; Kenny, Sean P.; Giesy, Daniel P.

    2015-01-01

    This and a companion paper propose techniques for constructing parametric mathematical models describing key features of the distribution of an output variable given input-output data. By contrast to standard models, which yield a single output value at each value of the input, Random Predictors Models (RPMs) yield a random variable at each value of the input. Optimization-based strategies for calculating RPMs having a polynomial dependency on the input and a linear dependency on the parameters are proposed. These formulations yield RPMs having various levels of fidelity in which the mean and the variance of the model's parameters, thus of the predicted output, are prescribed. As such they encompass all RPMs conforming to these prescriptions. The RPMs are optimal in the sense that they yield the tightest predictions for which all (or, depending on the formulation, most) of the observations are less than a fixed number of standard deviations from the mean prediction. When the data satisfies mild stochastic assumptions, and the optimization problem(s) used to calculate the RPM is convex (or, when its solution coincides with the solution to an auxiliary convex problem), the model's reliability, which is the probability that a future observation would be within the predicted ranges, can be bounded tightly and rigorously.

  5. Friction drive of an SAW motor. Part III: modeling.

    PubMed

    Shigematsu, Takashi; Kurosawa, Minoru Kuribayashi

    2008-10-01

    A 2-layer modeling method of friction drive of a surface acoustic wave motor is proposed. The surface layer accounts for the previously proposed point-contact friction drive model, which was generalized to correspond spatially to the underlying layer that is comprised of a 3-D elasticity field. A method to determine stiffness through the use of analytical solutions of 3-D contact problems bridges the 2 layers. Because the determined stiffness expresses the accuracy of the results regarding either layer, the validity of the results concerning the stiffness and the resulting stress field was evaluated by comparison with the results of finite element analysis. Furthermore, we executed numerical simulations by using the friction drive model, which were compared with the measured displacements of the frictional surface of the slider. The simulation accurately represented the normal displacement of the frictional surface; the modeling procedure in the normal direction was found to be reliable. However, because the friction coefficient drastically changes the tangential displacement, we could not discuss the reliability of the modeling procedure in the tangential direction. A thorough discussion of the friction drive would thus require further investigation of the friction phenomena. PMID:18986874

  6. Random Predictor Models for Rigorous Uncertainty Quantification: Part 2

    NASA Technical Reports Server (NTRS)

    Crespo, Luis G.; Kenny, Sean P.; Giesy, Daniel P.

    2015-01-01

    This and a companion paper propose techniques for constructing parametric mathematical models describing key features of the distribution of an output variable given input-output data. By contrast to standard models, which yield a single output value at each value of the input, Random Predictors Models (RPMs) yield a random variable at each value of the input. Optimization-based strategies for calculating RPMs having a polynomial dependency on the input and a linear dependency on the parameters are proposed. These formulations yield RPMs having various levels of fidelity in which the mean, the variance, and the range of the model's parameter, thus of the output, are prescribed. As such they encompass all RPMs conforming to these prescriptions. The RPMs are optimal in the sense that they yield the tightest predictions for which all (or, depending on the formulation, most) of the observations are less than a fixed number of standard deviations from the mean prediction. When the data satisfies mild stochastic assumptions, and the optimization problem(s) used to calculate the RPM is convex (or, when its solution coincides with the solution to an auxiliary convex problem), the model's reliability, which is the probability that a future observation would be within the predicted ranges, is bounded rigorously.

  7. Vapor mediated droplet interactions - models and mechanisms (Part 2)

    NASA Astrophysics Data System (ADS)

    Benusiglio, Adrien; Cira, Nate; Prakash, Manu

    2014-11-01

    When deposited on clean glass a two-component binary mixture of propylene glycol and water is energetically inclined to spread, as both pure liquids do. Instead the mixture forms droplets stabilized by evaporation induced surface tension gradients, giving them unique properties such as negligible hysteresis. When two of these special droplets are deposited several radii apart they attract each other. The vapor from one droplet destabilizes the other, resulting in an attraction force which brings both droplets together. We present a flux-based model for droplet stabilization and a model which connects the vapor profile to net force. These simple models capture the static and dynamic experimental trends, and our fundamental understanding of these droplets and their interactions allowed us to build autonomous fluidic machines.

  8. A multi-scale model of dislocation plasticity in α-Fe: Incorporating temperature, strain rate and non-Schmid effects

    SciTech Connect

    Lim, H.; Hale, L. M.; Zimmerman, J. A.; Battaile, C. C.; Weinberger, C. R.

    2015-01-05

    In this study, we develop an atomistically informed crystal plasticity finite element (CP-FE) model for body-centered-cubic (BCC) α-Fe that incorporates non-Schmid stress dependent slip with temperature and strain rate effects. Based on recent insights obtained from atomistic simulations, we propose a new constitutive model that combines a generalized non-Schmid yield law with aspects from a line tension (LT) model for describing activation enthalpy required for the motion of dislocation kinks. Atomistic calculations are conducted to quantify the non-Schmid effects while both experimental data and atomistic simulations are used to assess the temperature and strain rate effects. The parameterized constitutive equation is implemented into a BCC CP-FE model to simulate plastic deformation of single and polycrystalline Fe which is compared with experimental data from the literature. This direct comparison demonstrates that the atomistically informed model accurately captures the effects of crystal orientation, temperature and strain rate on the flow behavior of siangle crystal Fe. Furthermore, our proposed CP-FE model exhibits temperature and strain rate dependent flow and yield surfaces in polycrystalline Fe that deviate from conventional CP-FE models based on Schmid's law.

  9. A multi-scale model of dislocation plasticity in α-Fe: Incorporating temperature, strain rate and non-Schmid effects

    DOE PAGESBeta

    Lim, H.; Hale, L. M.; Zimmerman, J. A.; Battaile, C. C.; Weinberger, C. R.

    2015-01-05

    In this study, we develop an atomistically informed crystal plasticity finite element (CP-FE) model for body-centered-cubic (BCC) α-Fe that incorporates non-Schmid stress dependent slip with temperature and strain rate effects. Based on recent insights obtained from atomistic simulations, we propose a new constitutive model that combines a generalized non-Schmid yield law with aspects from a line tension (LT) model for describing activation enthalpy required for the motion of dislocation kinks. Atomistic calculations are conducted to quantify the non-Schmid effects while both experimental data and atomistic simulations are used to assess the temperature and strain rate effects. The parameterized constitutive equationmore » is implemented into a BCC CP-FE model to simulate plastic deformation of single and polycrystalline Fe which is compared with experimental data from the literature. This direct comparison demonstrates that the atomistically informed model accurately captures the effects of crystal orientation, temperature and strain rate on the flow behavior of siangle crystal Fe. Furthermore, our proposed CP-FE model exhibits temperature and strain rate dependent flow and yield surfaces in polycrystalline Fe that deviate from conventional CP-FE models based on Schmid's law.« less

  10. Modeling an electro-photographic printer, part I: monochrome systems

    NASA Astrophysics Data System (ADS)

    Kriss, Michael A.

    2007-01-01

    This paper will outline a simplified model for the development of toner dots on a reflective support. Using this model and the interaction of light between the reflective support and the dot's microstructure, the physical, optical and total dot-gain will be calculated, along with the resulting tone scales, for a variety of digital halftone patterns. The resulting tone reproduction curves and dot-gain will be compared with the classical literature on dot-gain and tone reproduction curves, more modern approaches and experimental data from the literature. A comparison to a well-defined experimental system will be shown.

  11. Modeling an electro-photographic printer, part II: color systems

    NASA Astrophysics Data System (ADS)

    Kriss, Michael A.

    2007-01-01

    This paper will outline a simplified model for the development of toner dots on a reflective support in a color electro-photographic system. A model developed for a monochrome system will be adapted to a color imaging system where four pigments, each capable of scatting light, is used to form a digital halftone image. The combination of physical and optical dot gains, interlayer scattering, on-dot and off-dot digital halftones will be explored and the results demonstrated in terms color shifts due to layer order and dot gain due to halftone geometry.

  12. First-principles study of point defects in an fcc Fe-10Ni-20Cr model alloy

    NASA Astrophysics Data System (ADS)

    Piochaud, J. B.; Klaver, T. P. C.; Adjanor, G.; Olsson, P.; Domain, C.; Becquart, C. S.

    2014-01-01

    The influence of the local environment on vacancy and self-interstitial formation energies has been investigated in a face-centered-cubic (fcc) Fe-10Ni-20Cr model alloy by analyzing an extensive set of first-principle calculations based on density functional theory. Chemical disorder has been considered by designing special quasirandom structures and four different collinear magnetic structures have been investigated in order to determine a relevant reference state to perform point defect calculations at 0 K. Two different convergence methods have also been used to characterize the importance of the method on the results. Although our fcc Fe-10Ni-20Cr would be better represented in terms of applications by the paramagnetic state, we found that the antiferromagnetic single-layer magnetic structure was the most stable at 0 K and we chose it as a reference state to determine the point defect properties. Point defects have been introduced in this reference state, i.e., vacancies and Fe-Fe, Fe-Ni, Fe-Cr, Cr-Cr, Ni-Ni, and Ni-Cr dumbbell interstitials oriented either parallel or perpendicular to the single layer antiferromagnetic planes. Each point defect studied was introduced at different lattice sites to consider a sufficient variety of local environments and analyze its influence on the formation energy values. We have estimated the point defect formation energies with linear regressions using variables which describe the local environment surrounding the point defects. The number and the position of Ni and Cr first nearest neighbors to the point defects were found to drive the evolution of the formation energies. In particular, Ni is found to decrease and Cr to increase the vacancy formation energy of the model alloy, while the opposite trends are found for the dumbbell interstitials. This study suggested that, to a first approximation, the first nearest atoms to point defects can provide reliable estimates of point defect formation energies.

  13. Simulation of Ferrite Formation in Fe-C Alloys Based on a Three-Dimensional Mixed-Mode Transformation Model

    NASA Astrophysics Data System (ADS)

    van Bohemen, S. M. C.; Bos, C.; Sietsma, J.

    2011-09-01

    A three-dimensional mixed-mode (MM) transformation model accounting for both soft impingement and hard impingement was developed that calculates the growth kinetics of ferrite grains in an austenite matrix. The simulations are compared to the kinetics of ferrite formation in high-purity Fe-C alloys for which phase-transformation kinetics were measured isothermally by dilatometry at several temperatures in the range of 973 K to 1043 K (700 °C to 770 °C). The interface mobility is obtained from the best fit of the data at 1023 K (750 °C) for which the nucleus density N is estimated from the final microstructure. Subsequently, the experimental ferrite kinetics in Fe-0.36C at the other temperatures are simulated. The values of N extracted from the fits can be described with a nucleation model. The significance of the MM calculations is rationalized by comparing the results for Fe-0.17C with simulations assuming purely diffusion-controlled (DC) and purely interface-controlled (IC) growth. Comparison of simulated fraction curves for Fe-0.57C with the three models demonstrates that the transformation in high-carbon steels is essentially DC.

  14. Local environment of Fe dopants in nanoscale Fe : CeO2-x oxygen storage material

    NASA Astrophysics Data System (ADS)

    Meledina, M.; Turner, S.; Galvita, V. V.; Poelman, H.; Marin, G. B.; van Tendeloo, G.

    2015-02-01

    Nanoscale Fe : CeO2-x oxygen storage material for the process of chemical looping has been investigated by advanced transmission electron microscopy and electron energy-loss spectroscopy before and after a model looping procedure, consisting of redox cycles at heightened temperature. Separately, the activity of the nanomaterial has been tested in a toluene total oxidation reaction. The results show that the material consists of ceria nanoparticles, doped with single Fe atoms and small FeOx clusters. The iron ion is partially present as Fe3+ in a solid solution within the ceria lattice. Furthermore, enrichment of reduced Fe2+ species is observed in nanovoids present in the ceria nanoparticles, as well as at the ceria surface. After chemical looping, agglomeration occurs and reduced nanoclusters appear at ceria grain boundaries formed by sintering. These clusters originate from surface Fe2+ aggregation, and from bulk Fe3+, which ``leaks out'' in reduced state after cycling to a slightly more agglomerated form. The activity of Fe : CeO2 during the toluene total oxidation part of the chemical looping cycle is ensured by the dopant Fe in the Fe1-xCexO2 solid solution, and by surface Fe species. These measurements on a model Fe : CeO2-x oxygen storage material give a unique insight into the behavior of dopants within a nanosized ceria host, and allow to interpret a plethora of (doped) cerium oxide-based reactions.Nanoscale Fe : CeO2-x oxygen storage material for the process of chemical looping has been investigated by advanced transmission electron microscopy and electron energy-loss spectroscopy before and after a model looping procedure, consisting of redox cycles at heightened temperature. Separately, the activity of the nanomaterial has been tested in a toluene total oxidation reaction. The results show that the material consists of ceria nanoparticles, doped with single Fe atoms and small FeOx clusters. The iron ion is partially present as Fe3+ in a solid solution

  15. Demonstrations in Solute Transport Using Dyes: Part II. Modeling.

    ERIC Educational Resources Information Center

    Butters, Greg; Bandaranayake, Wije

    1993-01-01

    A solution of the convection-dispersion equation is used to describe the solute breakthrough curves generated in the demonstrations in the companion paper. Estimation of the best fit model parameters (solute velocity, dispersion, and retardation) is illustrated using the method of moments for an example data set. (Author/MDH)

  16. Chemoviscosity modeling for thermosetting resin systems, part 3

    NASA Technical Reports Server (NTRS)

    Hou, T. H.; Bai, J. M.

    1988-01-01

    A new analytical model for simulating chemoviscosity resin has been formulated. The model is developed by modifying the well established Williams-Landel-Ferry (WLF) theory in polymer rheology for thermoplastic materials. By introducing a relationship between the glass transition temperature (T sub g (t)) and the degree of cure alpha(t) of the resin system under cure, the WLF theory can be modified to account for the factor of reaction time. Temperature-dependent functions of the modified WLF theory parameters C sub 1 (T) and C sub 2 (T) were determined from the isothermal cure data. Theoretical predictions of the model for the resin under dynamic heating cure cycles were shown to compare favorably with the experimental data. This work represents a progress toward establishing a chemoviscosity model which is capable of not only describing viscosity profiles accurately under various cure cycles, but also correlating viscosity data to the changes of physical properties associated with the structural transformations of the thermosetting resin systems during cure.

  17. Automated biowaste sampling system urine subsystem operating model, part 1

    NASA Technical Reports Server (NTRS)

    Fogal, G. L.; Mangialardi, J. K.; Rosen, F.

    1973-01-01

    The urine subsystem automatically provides for the collection, volume sensing, and sampling of urine from six subjects during space flight. Verification of the subsystem design was a primary objective of the current effort which was accomplished thru the detail design, fabrication, and verification testing of an operating model of the subsystem.

  18. Piezoresistive Cantilever Performance—Part I: Analytical Model for Sensitivity

    PubMed Central

    Park, Sung-Jin; Doll, Joseph C.; Pruitt, Beth L.

    2010-01-01

    An accurate analytical model for the change in resistance of a piezoresistor is necessary for the design of silicon piezoresistive transducers. Ion implantation requires a high-temperature oxidation or annealing process to activate the dopant atoms, and this treatment results in a distorted dopant profile due to diffusion. Existing analytical models do not account for the concentration dependence of piezoresistance and are not accurate for nonuniform dopant profiles. We extend previous analytical work by introducing two nondimensional factors, namely, the efficiency and geometry factors. A practical benefit of this efficiency factor is that it separates the process parameters from the design parameters; thus, designers may address requirements for cantilever geometry and fabrication process independently. To facilitate the design process, we provide a lookup table for the efficiency factor over an extensive range of process conditions. The model was validated by comparing simulation results with the experimentally determined sensitivities of piezoresistive cantilevers. We performed 9200 TSUPREM4 simulations and fabricated 50 devices from six unique process flows; we systematically explored the design space relating process parameters and cantilever sensitivity. Our treatment focuses on piezoresistive cantilevers, but the analytical sensitivity model is extensible to other piezoresistive transducers such as membrane pressure sensors. PMID:20336183

  19. Piezoresistive Cantilever Performance-Part I: Analytical Model for Sensitivity.

    PubMed

    Park, Sung-Jin; Doll, Joseph C; Pruitt, Beth L

    2010-02-01

    An accurate analytical model for the change in resistance of a piezoresistor is necessary for the design of silicon piezoresistive transducers. Ion implantation requires a high-temperature oxidation or annealing process to activate the dopant atoms, and this treatment results in a distorted dopant profile due to diffusion. Existing analytical models do not account for the concentration dependence of piezoresistance and are not accurate for nonuniform dopant profiles. We extend previous analytical work by introducing two nondimensional factors, namely, the efficiency and geometry factors. A practical benefit of this efficiency factor is that it separates the process parameters from the design parameters; thus, designers may address requirements for cantilever geometry and fabrication process independently. To facilitate the design process, we provide a lookup table for the efficiency factor over an extensive range of process conditions. The model was validated by comparing simulation results with the experimentally determined sensitivities of piezoresistive cantilevers. We performed 9200 TSUPREM4 simulations and fabricated 50 devices from six unique process flows; we systematically explored the design space relating process parameters and cantilever sensitivity. Our treatment focuses on piezoresistive cantilevers, but the analytical sensitivity model is extensible to other piezoresistive transducers such as membrane pressure sensors. PMID:20336183

  20. The Potsdam Parallel Ice Sheet Model (PISM-PIK) - Part 1: Model description

    NASA Astrophysics Data System (ADS)

    Winkelmann, R.; Martin, M. A.; Haseloff, M.; Albrecht, T.; Bueler, E.; Khroulev, C.; Levermann, A.

    2010-08-01

    We present the Potsdam Parallel Ice Sheet Model (PISM-PIK), developed at the Potsdam Institute for Climate Impact Research to be used for simulations of large-scale ice sheet-shelf systems. It is derived from the Parallel Ice Sheet Model (Bueler and Brown, 2009). Velocities are calculated by superposition of two shallow stress balance approximations within the entire ice covered region: the shallow ice approximation (SIA) is dominant in grounded regions and accounts for shear deformation parallel to the geoid. The plug-flow type shallow shelf approximation (SSA) dominates the velocity field in ice shelf regions and serves as a basal sliding velocity in grounded regions. Ice streams naturally emerge through this approach and can be identified diagnostically as regions with a significant contribution of membrane stresses to the local momentum balance. All lateral boundaries in PISM-PIK are free to evolve, including the grounding line and ice fronts. Ice shelf margins in particular are modeled using Neumann boundary conditions for the SSA equations, reflecting a hydrostatic stress imbalance along the vertical calving face. The ice front position is modeled using a subgrid scale representation of calving front motion (Albrecht et al., 2010) and a physically motivated dynamic calving law based on horizontal spreading rates. The model is validated within the Marine Ice Sheet Model Intercomparison Project (MISMIP) and is used for a dynamic equilibrium simulation of Antarctica under present-day conditions in the second part of this paper (Martin et al., 2010).

  1. Carbon dioxide stripping in aquaculture -- part III: model verification

    USGS Publications Warehouse

    Colt, John; Watten, Barnaby; Pfeiffer, Tim

    2012-01-01

    Based on conventional mass transfer models developed for oxygen, the use of the non-linear ASCE method, 2-point method, and one parameter linear-regression method were evaluated for carbon dioxide stripping data. For values of KLaCO2 < approximately 1.5/h, the 2-point or ASCE method are a good fit to experimental data, but the fit breaks down at higher values of KLaCO2. How to correct KLaCO2 for gas phase enrichment remains to be determined. The one-parameter linear regression model was used to vary the C*CO2 over the test, but it did not result in a better fit to the experimental data when compared to the ASCE or fixed C*CO2 assumptions.

  2. Advanced geothermal hydraulics model -- Phase 1 final report, Part 2

    SciTech Connect

    W. Zheng; J. Fu; W. C. Maurer

    1999-07-01

    An advanced geothermal well hydraulics model (GEODRIL) is being developed to accurately calculate bottom-hole conditions in these hot wells. In Phase 1, real-time monitoring and other improvements were added to GEODRIL. In Phase 2, GEODRIL will be integrated into Marconi's Intelligent Drilling Monitor (IDM) that will use artificial intelligence to detect lost circulation, fluid influxes and other circulation problems in geothermal wells. This software platform has potential for significantly reducing geothermal drilling costs.

  3. Modelling of cutting tool - soil interaction - part I: contact behaviour

    NASA Astrophysics Data System (ADS)

    Nardin, A.; Zavarise, G.; Schrefler, B. A.

    The unknown interaction of the cutting tools with geological settings represents an interesting problem for the excavation machinery industry. To simplify the non-linear aspects involved in the numerical analysis of such phenomena a strategy for an accurate soil modelling has to be defined. A possible approach is the discrete one, by considering the soil as an assembly of rigid spheres. In this work this strategy is adopted. The basic idea is to concentrate at the contact level between the spheres the real mechanical behaviour of the soil. For this purpose suitable contact models have been developed, where specific elasto-plastic laws have been implemented in the node-to-segment contact formulation. The framework for the plastic behaviour consists of a failure criterion, a one-dimensional, rate-independent elasto-plastic flow rule for the normal and the tangential force and a non-linear yield criterion. The final aim of this paper is to develop mechanical models to study the behaviour of stiff soils and rocks under different loading conditions.

  4. Cancer modelling in the NGS era - Part I: Emerging technology and initial modelling.

    PubMed

    Rovigatti, Ugo

    2015-11-01

    It is today indisputable that great progresses have been made in our molecular understanding of cancer cells, but an effective implementation of such knowledge into dramatic cancer-cures is still belated and yet desperately needed. This review gives a snapshot at where we stand today in this search for cancer understanding and definitive treatments, how far we have progressed and what are the major obstacles we will have to overcome both technologically and for disease modelling. In the first part, promising 3rd/4th Generation Sequencing Technologies will be summarized (particularly IonTorrent and OxfordNanopore technologies). Cancer modelling will be then reviewed from its origin in XIX Century Germany to today's NGS applications for cancer understanding and therapeutic interventions. Developments after Molecular Biology revolution (1953) are discussed as successions of three phases. The first, PH1, labelled "Clonal Outgrowth" (from 1960s to mid 1980s) was characterized by discoveries in cytogenetics (Nowell, Rowley) and viral oncology (Dulbecco, Bishop, Varmus), which demonstrated clonality. Treatments were consequently dominated by a "cytotoxic eradication" strategy with chemotherapeutic agents. In PH2, (from the mid 1980s to our days) the description of cancer as "Gene Networks" led to targeted-gene-therapies (TGTs). TGTs are the focus of Section 3: in view of their apparent failing (Ephemeral Therapies), alternative strategies will be discussed in review part II (particularly cancer immunotherapy, CIT). Additional Pitfalls impinge on the concepts of tumour heterogeneity (inter/intra; ITH). The described pitfalls set the basis for a new phase, PH3, which is called "NGS Era" and will be also discussed with ten emerging cancer models in the Review 2nd part. PMID:26427785

  5. A General Reversible Hereditary Constitutive Model. Part 1; Theoretical Developments

    NASA Technical Reports Server (NTRS)

    Saleeb, A. F.; Arnold, S. M.

    1997-01-01

    Using an internal-variable formalism as a starting point, we describe the viscoelastic extension of a previously-developed viscoplasticity formulation of the complete potential structure type. It is mainly motivated by experimental evidence for the presence of rate/time effects in the so-called quasilinear, reversible, material response range. Several possible generalizations are described, in the general format of hereditary-integral representations for non-equilibrium, stress-type, state variables, both for isotropic as well as anisotropic materials. In particular, thorough discussions are given on the important issues of thermodynamic admissibility requirements for such general descriptions, resulting in a set of explicit mathematical constraints on the associated kernel (relaxation and creep compliance) functions. In addition, a number of explicit, integrated forms are derived, under stress and strain control to facilitate the parametric and qualitative response characteristic studies reported here, as well as to help identify critical factors in the actual experimental characterizations from test data that will be reported in Part II.

  6. AIR INGRESS ANALYSIS: PART 2 – COMPUTATIONAL FLUID DYNAMIC MODELS

    SciTech Connect

    Chang H. Oh; Eung S. Kim; Richard Schultz; Hans Gougar; David Petti; Hyung S. Kang

    2011-01-01

    The Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy, is performing research and development that focuses on key phenomena important during potential scenarios that may occur in very high temperature reactors (VHTRs). Phenomena Identification and Ranking Studies to date have ranked an air ingress event, following on the heels of a VHTR depressurization, as important with regard to core safety. Consequently, the development of advanced air ingress-related models and verification and validation data are a very high priority. Following a loss of coolant and system depressurization incident, air will enter the core of the High Temperature Gas Cooled Reactor through the break, possibly causing oxidation of the in-the core and reflector graphite structure. Simple core and plant models indicate that, under certain circumstances, the oxidation may proceed at an elevated rate with additional heat generated from the oxidation reaction itself. Under postulated conditions of fluid flow and temperature, excessive degradation of the lower plenum graphite can lead to a loss of structural support. Excessive oxidation of core graphite can also lead to the release of fission products into the confinement, which could be detrimental to a reactor safety. Computational fluid dynamic model developed in this study will improve our understanding of this phenomenon. This paper presents two-dimensional and three-dimensional CFD results for the quantitative assessment of the air ingress phenomena. A portion of results of the density-driven stratified flow in the inlet pipe will be compared with results of the experimental results.

  7. Beam Heating of Samples: Modeling and Verification. Part 2

    NASA Technical Reports Server (NTRS)

    Kazmierczak, Michael; Gopalakrishnan, Pradeep; Kumar, Raghav; Banerjee Rupak; Snell, Edward; Bellamy, Henry; Rosenbaum, Gerd; vanderWoerd, Mark

    2006-01-01

    Energy absorbed from the X-ray beam by the sample requires cooling by forced convection (i.e. cryostream) to minimize temperature increase and the damage caused to the sample by the X-ray heating. In this presentation we will first review the current theoretical models and recent studies in the literature, which predict the sample temperature rise for a given set of beam parameters. It should be noted that a common weakness of these previous studies is that none of them provide actual experimental confirmation. This situation is now remedied in our investigation where the problem of x-ray sample heating is taken up once more. We have theoretically investigated, and at the same time, in addition to the numerical computations, performed experiments to validate the predictions. We have modeled, analyzed and experimentally tested the temperature rise of a 1 mm diameter glass sphere (sample surrogate) exposed to an intense synchrotron X-ray beam, while it is being cooled in a uniform flow of nitrogen gas. The heat transfer, including external convection and internal heat conduction was theoretically modeled using CFD to predict the temperature variation in the sphere during cooling and while it was subjected to an undulator (ID sector 19) X-ray beam at the APS. The surface temperature of the sphere during the X-ray beam heating was measured using the infrared camera measurement technique described in a previous talk. The temperatures from the numerical predictions and experimental measurements are compared and discussed. Additional results are reported for the two different sphere sizes and for two different supporting pin orientations.

  8. Hydrogeologic role of geologic structures. Part 2: analytical models

    NASA Astrophysics Data System (ADS)

    Levens, Russell L.; Williams, Roy E.; Ralston, Dale R.

    1994-04-01

    This paper is the second of two papers that address the influence of geologic structures on ground water flow at various scales in fractured rocks. The ultimate purpose of this research is to investigate the feasibility of grouting preferentially permeable zones as a strategy to minimize the production of acid mine drainage in underground hard rock mines in which the major permeability is structure and fracture controlled. The aim of grouting is to reduce permeability around mined-out openings, to minimize the rate of inflow of ground water into such openings via the structurally controlled preferentially permeable pathways. A series of hydraulic stress tests were conducted to help characterize the role of geologic structures in controlling the ground water flow system in the vicinity of the Bunker Hill Mine in north Idaho. The results of these tests indicate that most of the ground water that flows from the underground drillholes used for hydraulic stress testing is derived from a few discrete, structurally produced fracture zones that are more or less connected through smaller-scale fractures. Four types of analytical models are considered as a means of analyzing the results of multiple drillhole hydraulic stress tests, as follows: cross-hole equivalent porous media; double-porosity equivalent porous media; a solution to flow in and around a single vertical fracture; leaky equivalent porous media, partial penetration. The estimation of hydraulic coefficients in complex fractured rock environments involves the combined application of a number of deterministic analytical models. The models to be used are selected dependent on the location of the drawdown observations relative to the water-producing zone and the length of the test. The result of the tests can be related to the permeability hierarchy discussed in our first paper.

  9. Models of spinal cord injury: Part 3. Dynamic load technique.

    PubMed

    Black, P; Markowitz, R S; Damjanov, I; Finkelstein, S D; Kushner, H; Gillespie, J; Feldman, M

    1988-01-01

    Having previously studied a static load model of cord injury in rats, we report here an evaluation of a dynamic (weight drop) technique. Under general anesthesia, Sprague-Dawley rats were subjected to a laminectomy at T12, after which a 10-g weight was dropped onto a force transducer and impounder resting on the spinal cord; the weight drop distances varied in different groups from 0 (control) in increments of 2.5 cm to a maximal height of 17.5 cm. A strain gauge attached to the force transducer yielded an oscilloscopic wave form from which force of impact (peak force and impulse) was calculated. Eighty-six animals were used in this parametric study. The animals were observed for 4 weeks postinjury with two tests of motor recovery (Tarlov score for locomotion and the inclined plane test). After sacrifice at 4 weeks, the spinal cords were removed and, with the use of preset criteria, qualitative histopathological scoring of the extent of tissue damage was carried out. We found that the variable height of weight drop was capable of producing a graded injury that correlated with the force of injury (as measured by the force transducer) and with the outcome parameters of functional recovery and degree of morphological damage in the spinal cord. Histopathologically, there was a tendency to central cavitation of the cord. Both the static load and the dynamic load techniques seem to be valid models of spinal cord injury. Pathologically, however, the tissue damage after static load injury involved primarily the dorsal half of the cord. By contrast, the dynamic load technique produced central cavitation comparable to that observed in human spinal cord injury. In this respect, the dynamic model seems to be superior and its use is therefore recommended for studies of therapeutic intervention for spinal cord injury. PMID:3344087

  10. GSTARS computer models and their applications, part I: theoretical development

    USGS Publications Warehouse

    Yang, C.T.; Simoes, F.J.M.

    2008-01-01

    GSTARS is a series of computer models developed by the U.S. Bureau of Reclamation for alluvial river and reservoir sedimentation studies while the authors were employed by that agency. The first version of GSTARS was released in 1986 using Fortran IV for mainframe computers. GSTARS 2.0 was released in 1998 for personal computer application with most of the code in the original GSTARS revised, improved, and expanded using Fortran IV/77. GSTARS 2.1 is an improved and revised GSTARS 2.0 with graphical user interface. The unique features of all GSTARS models are the conjunctive use of the stream tube concept and of the minimum stream power theory. The application of minimum stream power theory allows the determination of optimum channel geometry with variable channel width and cross-sectional shape. The use of the stream tube concept enables the simulation of river hydraulics using one-dimensional numerical solutions to obtain a semi-two- dimensional presentation of the hydraulic conditions along and across an alluvial channel. According to the stream tube concept, no water or sediment particles can cross the walls of stream tubes, which is valid for many natural rivers. At and near sharp bends, however, sediment particles may cross the boundaries of stream tubes. GSTARS3, based on FORTRAN 90/95, addresses this phenomenon and further expands the capabilities of GSTARS 2.1 for cohesive and non-cohesive sediment transport in rivers and reservoirs. This paper presents the concepts, methods, and techniques used to develop the GSTARS series of computer models, especially GSTARS3. ?? 2008 International Research and Training Centre on Erosion and Sedimentation and the World Association for Sedimentation and Erosion Research.

  11. Thermodynamic properties of Fe-S alloys from molecular dynamics modeling: Implications for the lunar fluid core

    NASA Astrophysics Data System (ADS)

    Kuskov, Oleg L.; Belashchenko, David K.

    2016-09-01

    Density and sound velocity of Fe-S liquids for the P-T parameters of the lunar core have not been constrained well. From the analysis of seismic wave travel time, Weber et al. (2011) proposed that the lunar core is composed of iron alloyed with ⩽6 wt% of light elements, such as S. A controversial issue in models of planetary core composition concerns whether Fe-S liquids under high pressure - temperature conditions provide sound velocity and density data, which match the seismic model. Here we report the results of molecular dynamics (MD) simulations of iron-sulfur alloys based on Embedded Atom Model (EAM). The results of calculations include caloric, thermal and elastic properties of Fe-S alloys at concentrations of sulfur 0-18 at.%, temperatures up to 2500 K and pressures up to 14 GPa. The effect of sulfur on the elastic properties of Fe-rich melts is most evident in the notably decreased density with added S content. In the MD simulation, the density and bulk modulus KT of liquid Fe-S decrease with increasing sulfur content, while the bulk modulus KS decreases as a whole but has some fluctuations with increasing sulfur content. The sound velocity increases with increasing pressure, but depends weakly on temperature and the concentration of sulfur. For a fluid Fe-S core of the Moon (∼5 GPa/2000 K) with 6-16 at.% S (3.5-10 wt%), the sound velocity and density may be estimated at the level of 4000 m s-1 and 6.25-7.0 g cm-3. Comparison of thermodynamic calculations with the results of interpretation of seismic observations shows good agreement of P-wave velocities in the liquid outer core, while the core density does not match the seismic models. At such concentrations of sulfur and a density by 20-35% higher than the model seismic density, a radius for the fluid outer core should be less than about 330 km found by Weber et al. because at the specified mass and moment of inertia values of the Moon an increase of the core density leads to a decrease of the core

  12. 12 CFR Appendix H to Part 1026 - Closed-End Model Forms and Clauses

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 9 2014-01-01 2014-01-01 false Closed-End Model Forms and Clauses H Appendix H to Part 1026 Banks and Banking BUREAU OF CONSUMER FINANCIAL PROTECTION TRUTH IN LENDING (REGULATION Z) Pt. 1026, App. H Appendix H to Part 1026—Closed-End Model Forms and Clauses H-1Credit Sale Model Form (§ 1026.18) H-2Loan Model Form (§ 1026.18)...

  13. Magnetic cluster expansion model for random and ordered magnetic face-centered cubic Fe-Ni-Cr alloys

    NASA Astrophysics Data System (ADS)

    Lavrentiev, M. Yu.; Wróbel, J. S.; Nguyen-Manh, D.; Dudarev, S. L.; Ganchenkova, M. G.

    2016-07-01

    A Magnetic Cluster Expansion model for ternary face-centered cubic Fe-Ni-Cr alloys has been developed, using DFT data spanning binary and ternary alloy configurations. Using this Magnetic Cluster Expansion model Hamiltonian, we perform Monte Carlo simulations and explore magnetic structures of alloys over the entire range of compositions, considering both random and ordered alloy structures. In random alloys, the removal of magnetic collinearity constraint reduces the total magnetic moment but does not affect the predicted range of compositions where the alloys adopt low-temperature ferromagnetic configurations. During alloying of ordered fcc Fe-Ni compounds with Cr, chromium atoms tend to replace nickel rather than iron atoms. Replacement of Ni by Cr in ordered alloys with high iron content increases the Curie temperature of the alloys. This can be explained by strong antiferromagnetic Fe-Cr coupling, similar to that found in bcc Fe-Cr solutions, where the Curie temperature increase, predicted by simulations as a function of Cr concentration, is confirmed by experimental observations. In random alloys, both magnetization and the Curie temperature decrease abruptly with increasing chromium content, in agreement with experiment.

  14. Polarimetric Signatures of Sea Ice. Part 1; Theoretical Model

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Drinkwater, M. R.

    1995-01-01

    Physical, structural, and electromagnetic properties and interrelating processes in sea ice are used to develop a composite model for polarimetric backscattering signatures of sea ice. Physical properties of sea ice constituents such as ice, brine, air, and salt are presented in terms of their effects on electromagnetic wave interactions. Sea ice structure and geometry of scatterers are related to wave propagation, attenuation, and scattering. Temperature and salinity, which are determining factors for the thermodynamic phase distribution in sea ice, are consistently used to derive both effective permittivities and polarimetric scattering coefficients. Polarimetric signatures of sea ice depend on crystal sizes and brine volumes, which are affected by ice growth rates. Desalination by brine expulsion, drainage, or other mechanisms modifies wave penetration and scattering. Sea ice signatures are further complicated by surface conditions such as rough interfaces, hummocks, snow cover, brine skim, or slush layer. Based on the same set of geophysical parameters characterizing sea ice, a composite model is developed to calculate effective permittivities and backscattering covariance matrices at microwave frequencies for interpretation of sea ice polarimetric signatures.

  15. Automated generation of uniform Group Technology part codes from solid model data

    SciTech Connect

    Ames, A.L.

    1987-01-01

    Group Technology is a manufacturing theory based on the identification of similar parts and the subsequent grouping of these parts to enhance the manufacturing process. Part classification and coding systems group parts into families based on design and manufacturing attributes. Traditionally, humans code parts by examining a blueprint of the part to find important features as defined in a set of part classification rules. This process can be difficult and time consuming due to the complexity of the classification system. Coding specifications can require considerable interpretation, making consistency a problem for organizations employing many (human) part coders. A solution to these problems is to automate the part coding process in software, using a CAD database as input. It is straightforward to translate the part classification rules into a rule based expert system. A more difficult task is the recognition of part coding features from a CAD database. Previous research in feature recognition has concentrated on material removal features (depressions such as holes, pockets and slots). Part classification requires the ability to recognize such features, plus other features such as hole patterns, symmetries and overall part shape. This paper extends feature recognition to include part classification and coding features and describes an expert system for automated part classification and coding being developed. This system accepts boundary-representation solid model data and generates a part code. Specific feature recognition problems (such as intersecting features) and the methods developed to solve these problems are presented.

  16. Anisotropic constitutive model and FE simulation of the sintering process of slip cast traditional porcelain

    NASA Astrophysics Data System (ADS)

    Sarbandi, B.; Besson, J.; Boussuge, M.; Ryckelynck, D.

    2010-06-01

    Slip cast ceramic components undergo both sintering shrinkage and creep deformation caused by gravity during the firing cycle. In addition sintering may be anisotropic due to the development of preferential directions during slip casting. Both phenomena induce complex deformations of parts which make the design of casting molds difficult. To help solving this problem, anisotropic constitutive equations are proposed to represent the behavior of the ceramic compacts during sintering. The model parameters are identified using tests allowing to characterize both sintering and creep. The model was implemented in a finite element software and used to simulate the deformation of a traditional ceramic object during sintering.

  17. Anisotropic constitutive model and FE simulation of the sintering process of slip cast traditional porcelain

    SciTech Connect

    Sarbandi, B.; Besson, J.; Boussuge, M.; Ryckelynck, D.

    2010-06-15

    Slip cast ceramic components undergo both sintering shrinkage and creep deformation caused by gravity during the firing cycle. In addition sintering may be anisotropic due to the development of preferential directions during slip casting. Both phenomena induce complex deformations of parts which make the design of casting molds difficult. To help solving this problem, anisotropic constitutive equations are proposed to represent the behavior of the ceramic compacts during sintering. The model parameters are identified using tests allowing to characterize both sintering and creep. The model was implemented in a finite element software and used to simulate the deformation of a traditional ceramic object during sintering.

  18. 57Fe Mössbauer spectroscopy used to develop understanding of a diamond preservation index model

    NASA Astrophysics Data System (ADS)

    Yambissa, M. T.; Forder, S. D.; Bingham, P. A.

    2016-12-01

    57Fe Mössbauer spectroscopy has provided precise and accurate iron redox ratios Fe2+/Fe3+ in ilmenite, FeTiO3, found within kimberlite samples from the Catoca and Camatxia kimberlite pipes from N.E. Angola. Ilmenite is one of the key indicator minerals for diamond survival and it is also one of the iron-bearing minerals with iron naturally occurring in one or both of the oxidation states Fe3+ and Fe2+. For this reason it is a good indicator for studying oxygen fugacities ( fO2) in mineral samples, which can then be related to iron redox ratios, Fe2+/Fe3+. In this paper we demonstrate that the oxidation state of the ilmenite mineral inclusion from sampled kimberlite rock is a key indicator of the oxidation state of the host kimberlite assemblage, which in turn determines the genesis of diamond, grade variation and diamond quality. Ilmenite samples from the two different diamondiferous kimberlite localities (Catoca and Camatxia) in the Lucapa graben, N.E. Angola, were studied using Mössbauer spectroscopy and X-Ray Diffractometry, in order to infer the oxidation state of their source regions in the mantle, oxygen partial pressure and diamond preservation conditions. The iron redox ratios, obtained using Mössbauer spectroscopy, show that the Catoca diamond kimberlite is more oxidised than kimberlite found in the Camatxia pipe, which is associated within the same geological tectonic structure. Here we demonstrate that57Fe Mössbauer spectroscopy can assist geologists and mining engineers to effectively evaluate and determine whether kimberlite deposits are economically feasible for diamond mining.

  19. Heterogeneous disease progression and treatment response in a C3HeB/FeJ mouse model of tuberculosis

    PubMed Central

    Lanoix, Jean-Philippe; Lenaerts, Anne J.; Nuermberger, Eric L.

    2015-01-01

    ABSTRACT Mice are the most commonly used species for non-clinical evaluations of drug efficacy against tuberculosis (TB). Unlike commonly used strains, C3HeB/FeJ mice develop caseous necrosis in the lung, which might alter the representation of drug efficacy in a way that is more like human TB. Because the development of such pathology requires time, we investigated the effect of infection incubation period on the activity of six drugs in C3HeB/FeJ and BALB/c mice. Mice were aerosol infected and held for 6, 10 or 14 weeks before receiving therapy with rifampin (RIF), rifapentine (RPT), pyrazinamide (PZA), linezolid (LZD), sutezolid (PNU) or metronidazole (MTZ) for 4-8 weeks. Outcomes included pathological assessments, pH measurements of liquefied caseum and assessment of colony-forming unit (CFU) counts from lung cultures. Remarkable heterogeneity in the timing and extent of disease progression was observed in C3HeB/FeJ mice, largely independent of incubation period. Likewise, drug efficacy in C3HeB/FeJ mice was not affected by incubation period. However, for PZA, LZD and PNU, dichotomous treatment effects correlating with the presence or absence of large caseous lesions were observed. In the case of PZA, its poor activity in the subset of C3HeB/FeJ mice with large caseous lesions might be explained by the pH of 7.36±0.09 measured in liquefied caseum. This study highlights the potential value of C3HeB/FeJ mice for non-clinical efficacy testing, especially for investigating the interaction of lesion pathology and drug effect. Careful use of this model could enhance the bridging of non-clinical results with clinical outcomes. PMID:26035868

  20. Heterogeneous disease progression and treatment response in a C3HeB/FeJ mouse model of tuberculosis.

    PubMed

    Lanoix, Jean-Philippe; Lenaerts, Anne J; Nuermberger, Eric L

    2015-06-01

    Mice are the most commonly used species for non-clinical evaluations of drug efficacy against tuberculosis (TB). Unlike commonly used strains, C3HeB/FeJ mice develop caseous necrosis in the lung, which might alter the representation of drug efficacy in a way that is more like human TB. Because the development of such pathology requires time, we investigated the effect of infection incubation period on the activity of six drugs in C3HeB/FeJ and BALB/c mice. Mice were aerosol infected and held for 6, 10 or 14 weeks before receiving therapy with rifampin (RIF), rifapentine (RPT), pyrazinamide (PZA), linezolid (LZD), sutezolid (PNU) or metronidazole (MTZ) for 4-8 weeks. Outcomes included pathological assessments, pH measurements of liquefied caseum and assessment of colony-forming unit (CFU) counts from lung cultures. Remarkable heterogeneity in the timing and extent of disease progression was observed in C3HeB/FeJ mice, largely independent of incubation period. Likewise, drug efficacy in C3HeB/FeJ mice was not affected by incubation period. However, for PZA, LZD and PNU, dichotomous treatment effects correlating with the presence or absence of large caseous lesions were observed. In the case of PZA, its poor activity in the subset of C3HeB/FeJ mice with large caseous lesions might be explained by the pH of 7.36±0.09 measured in liquefied caseum. This study highlights the potential value of C3HeB/FeJ mice for non-clinical efficacy testing, especially for investigating the interaction of lesion pathology and drug effect. Careful use of this model could enhance the bridging of non-clinical results with clinical outcomes. PMID:26035868

  1. Earth mineralogical model: Gibbs free energy minimization computation in the system MgOFeOSiO 2

    NASA Astrophysics Data System (ADS)

    Saxena, S. K.

    1996-07-01

    A thermodynamic database which is consistent with most available phase equilibrium experiments and calorimetric and physical measurements on the solids in the system MgOFeOSiO 2 is established for the phases with the compositions (Mg, Fe)SiO 3 (garnet, perovskite, pyroxene, and ilmenite), (Mg, Fe) 2SiO 4 (olivine, β, and γ phases), SiO 2 (stishovite and coesite), and (Mg, Fe)O (periclase and wustite). The data are systematized by using the high temperature Birch-Murnaghan equation of state which includes the pressure and temperature dependent bulk modulus ( K) and temperature dependent thermal expansion (α) of the solids. The systematized thermodynamic data contains heat capacity ( Cp) data, which is internally consistent with the data on α, K, volume, and temperature. Such a systematized database is used to calculate, by the method of minimization of Gibbs free energy, the mineralogical composition of the peridotitic/pyrolitic and chondritic MgOFeOSiO 2 mantles. The model corresponds closely to the seismological PREM (Preliminary Earth Reference Model) in predicting the major seismic discontinuities. However, such discontinuities resulting from reactions or phase transformation are not as sharp as the seismic ones. Calculated adiabatic geothermal gradient starting at 6 GPa and 1500 K reaches a temperature of 2046 K at the core/mantle pressure (135 GPa) in a pyrolite mantle. The model Earth parameters in the lower mantle are (PREM parameters in bracket): Ks = 308 (306) to 687 (656) GPa; φ = 70 (69) to 121 (118) km 2 s -2.

  2. Characterization of atomic-level structure in Fe-based amorphous and nanocrystalline alloy by experimental and modeling methods

    SciTech Connect

    Babilas, Rafał

    2015-09-15

    The atomic structure of Fe{sub 70}Nb{sub 10}B{sub 20} alloy in “as-cast” state and after annealing was investigated using high-energy X-ray diffraction (XRD), Mössbauer spectroscopy (MS) and high resolution transmission electron microscopy (HRTEM). The HRTEM observations allowed to indicate some medium-range order (MRO) regions about 2 nm in size and formation of some kinds of short-range order (SRO) structures represented by atomic clusters with diameter ca. 0.5 nm. The Reverse Monte Carlo (RMC) method basing on the results of XRD measurements was used in modeling the atomic structure of Fe-based alloy. The structural model was described by peak values of partial pair correlation functions and coordination numbers determined by Mössbauer spectroscopy investigations. The three-dimensional configuration box of atoms was obtained from the RMC simulation and the representative Fe-centered clusters were taken from the calculated structure. According to the Gonser et al. approach, the measured spectra of alloy studied were decomposed into 5 subspectra representing average Fe–Fe coordination numbers. Basing on the results of disaccommodation of magnetic permeability, which is sensitive to the short order of the random packing of atoms, it was stated that an occurrence of free volume is not detected after nanocrystallization process. - Highlights: • Atomic cluster model of amorphous structure was proposed for studied glassy alloy. • Short range order (ca. 0.5 nm) regions interpreted as clusters were identified by HREM. • Clusters correspond to coordination numbers (N = 4,6,8,9) calculated by using Gonser approach. • Medium-range order (ca. 2 nm) could be referred to few atomic clusters. • SRO regions are able to grow up as nuclei of crystalline bcc Fe and iron borides. • Crystalline particles have spherical morphology with an average diameter of 20 nm.

  3. Interplay between magnetism and energetics in Fe-Cr alloys from a predictive noncollinear magnetic tight-binding model

    NASA Astrophysics Data System (ADS)

    Soulairol, R.; Barreteau, C.; Fu, Chu-Chun

    2016-07-01

    Magnetism is a key driving force controlling several thermodynamic and kinetic properties of Fe-Cr systems. We present a tight-binding model for Fe-Cr, where magnetism is treated beyond the usual collinear approximation. A major advantage of this model consists in a rather simple fitting procedure. In particular, no specific property of the binary system is explicitly required in the fitting database. The present model is proved to be accurate and highly transferable for electronic, magnetic, and energetic properties of a large variety of structural and chemical environments: surfaces, interfaces, embedded clusters, and the whole compositional range of the binary alloy. The occurrence of noncollinear magnetic configurations caused by magnetic frustrations is successfully predicted. The present tight-binding approach can apply to other binary magnetic transition-metal alloys. It is expected to be particularly promising if the size difference between the alloying elements is rather small and the electronic properties prevail.

  4. High Strain Rate Deformation Modeling of a Polymer Matrix Composite. Part 2; Composite Micromechanical Model

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1998-01-01

    Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this second paper of a two part report, a three-dimensional composite micromechanical model is described which allows for the analysis of the rate dependent, nonlinear deformation response of a polymer matrix composite. Strain rate dependent inelastic constitutive equations utilized to model the deformation response of a polymer are implemented within the micromechanics method. The deformation response of two representative laminated carbon fiber reinforced composite materials with varying fiber orientation has been predicted using the described technique. The predicted results compare favorably to both experimental values and the response predicted by the Generalized Method of Cells, a well-established micromechanics analysis method.

  5. 12 CFR >appendix A to Part 239 - Mutual Holding Company Model Charter

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 4 2013-01-01 2013-01-01 false Mutual Holding Company Model Charter A >Appendix A to Part 239 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE... Part 239—Mutual Holding Company Model Charter FEDERAL MUTUAL HOLDING COMPANY CHARTER Section...

  6. 31 CFR Appendix A to Part 212 - Model Notice to Account Holder

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance: Treasury 2 2014-07-01 2014-07-01 false Model Notice to Account Holder A Appendix A to Part 212 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued... CONTAINING FEDERAL BENEFIT PAYMENTS Pt. 212, App. A Appendix A to Part 212—Model Notice to Account Holder...

  7. 12 CFR Appendix B to Part 222 - Model Notices of Furnishing Negative Information

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Model Notices of Furnishing Negative Information B Appendix B to Part 222 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM FAIR CREDIT REPORTING (REGULATION V) Pt. 222, App. B Appendix B to Part 222—Model Notices of Furnishing...

  8. 12 CFR Appendix C to Part 1022 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 8 2014-01-01 2014-01-01 false Model Forms for Opt-Out Notices C Appendix C to Part 1022 Banks and Banking BUREAU OF CONSUMER FINANCIAL PROTECTION FAIR CREDIT REPORTING (REGULATION V) Pt. 1022, App. C Appendix C to Part 1022—Model Forms for Opt-Out Notices a. Although use of the...

  9. A numerical model of aerosol scavenging: Part 1, Microphysics parameterization

    SciTech Connect

    Molenkamp, C.R.; Bradley, M.M.

    1991-09-01

    We have developed a three-dimensional numerical model (OCTET) to simulate the dynamics and microphysics of clouds and the transport, diffusion and precipitation scavenging of aerosol particles. In this paper we describe the cloud microphysics and scavenging parameterizations. The representation of cloud microphysics is a bulk- water parameterization which includes water vapor and five types of hydrometeors (cloud droplets, rain drops, ice crystals, snow, and graupel). A parallel parameterization represents the scavenging interactions between pollutant particles and hydrometeors including collection of particles because of condensation nucleation, Brownian and phoretic attachment, and inertial capture, resuspension because of evaporation and sublimation; and transfer interactions where particles collected by one type of hydrometeor are transferred to another type of freezing, melting, accretion, riming and autoconversion.

  10. Fatigue of notched fiber composite laminates. Part 1: Analytical model

    NASA Technical Reports Server (NTRS)

    Mclaughlin, P. V., Jr.; Kulkarni, S. V.; Huang, S. N.; Rosen, B. W.

    1975-01-01

    A description is given of a semi-empirical, deterministic analysis for prediction and correlation of fatigue crack growth, residual strength, and fatigue lifetime for fiber composite laminates containing notches (holes). The failure model used for the analysis is based upon composite heterogeneous behavior and experimentally observed failure modes under both static and fatigue loading. The analysis is consistent with the wearout philosophy. Axial cracking and transverse cracking failure modes are treated together in the analysis. Cracking off-axis is handled by making a modification to the axial cracking analysis. The analysis predicts notched laminate failure from unidirectional material fatique properties using constant strain laminate analysis techniques. For multidirectional laminates, it is necessary to know lamina fatique behavior under axial normal stress, transverse normal stress and axial shear stress. Examples of the analysis method are given.

  11. Quantitative modeling of the equilibration of two-phase solid-liquid Fe by atomistic simulations on diffusive time scales

    NASA Astrophysics Data System (ADS)

    Asadi, Ebrahim; Asle Zaeem, Mohsen; Nouranian, Sasan; Baskes, Michael I.

    2015-01-01

    In this paper, molecular dynamics (MD) simulations based on the modified-embedded atom method (MEAM) and a phase-field crystal (PFC) model are utilized to quantitatively investigate the solid-liquid properties of Fe. A set of second nearest-neighbor MEAM parameters for high-temperature applications are developed for Fe, and the solid-liquid coexisting approach is utilized in MD simulations to accurately calculate the melting point, expansion in melting, latent heat, and solid-liquid interface free energy, and surface anisotropy. The required input properties to determine the PFC model parameters, such as liquid structure factor and fluctuations of atoms in the solid, are also calculated from MD simulations. The PFC parameters are calculated utilizing an iterative procedure from the inputs of MD simulations. The solid-liquid interface free energy and surface anisotropy are calculated using the PFC simulations. Very good agreement is observed between the results of our calculations from MEAM-MD and PFC simulations and the available modeling and experimental results in the literature. As an application of the developed model, the grain boundary free energy of Fe is calculated using the PFC model and the results are compared against experiments.

  12. Kinetic modeling of 52Fe/52mMn-citrate at the blood-brain barrier by positron emission tomography.

    PubMed

    Calonder, C; Würtenberger, P I; Maguire, R P; Pellikka, R; Leenders, K L

    1999-11-01

    The kinetics of iron at the blood-brain barrier of the monkey were studied in vivo using positron emission tomography (PET) and the tracer 52Fe/52mMn-citrate. 52mMn is the beta(+)-emitting daughter nuclide of 52Fe and therefore contributes to the observed signal and background in the PET images and may influence the quantification of physiological relevant iron parameters. The kinetics of pure (52m)Mn-citrate at the blood-brain barrier of the monkey were studied experimentally, and the analysis of the data with a reasonable compartment model led to equal efflux and influx parameters for Mn (1.35 +/- 0.3 x 10(-2) min(-1)). By using complexes between Mn and diethylenetriaminepentaacetic acid, the validity of the proposed model could be confirmed. To describe the observed kinetics of 52Fe/(52m)Mn-citrate, the manganese model was coupled to an iron model, which finally allowed the quantification of two iron-specific parameters: an input rate into global brain tissue of 7.15 +/- 2.6 x 10(-4) min(-1) and a time delay of roughly 24 min to account for the observed activities. The simpler linearization procedure has been proposed and could be applied to all our data sets and is able to replace the complicated nonlinear iron/manganese tracer kinetic model neglecting any influence of manganese on the analysis. PMID:10537064

  13. Phase Field Modeling of Cyclic Austenite-Ferrite Transformations in Fe-C-Mn Alloys

    NASA Astrophysics Data System (ADS)

    Chen, Hao; Zhu, Benqiang; Militzer, Matthias

    2016-08-01

    Three different approaches for considering the effect of Mn on the austenite-ferrite interface migration in an Fe-0.1C-0.5Mn alloy have been coupled with a phase field model (PFM). In the first approach (PFM-I), only long-range C diffusion is considered while Mn is assumed to be immobile during the phase transformations. Both long-range C and Mn diffusions are considered in the second approach (PFM-II). In the third approach (PFM-III), long-range C diffusion is considered in combination with the Gibbs energy dissipation due to Mn diffusion inside the interface instead of solving for long-range diffusion of Mn. The three PFM approaches are first benchmarked with isothermal austenite-to-ferrite transformation at 1058.15 K (785 °C) before considering cyclic phase transformations. It is found that PFM-II can predict the stagnant stage and growth retardation experimentally observed during cycling transformations, whereas PFM-III can only replicate the stagnant stage but not the growth retardation and PFM-I predicts neither the stagnant stage nor the growth retardation. The results of this study suggest a significant role of Mn redistribution near the interface on reducing transformation rates, which should, therefore, be considered in future simulations of austenite-ferrite transformations in steels, particularly at temperatures in the intercritical range and above.

  14. Coarse Grained Approach to First Principles Modeling of Radiation Cascade in Large Fe Supercells

    NASA Astrophysics Data System (ADS)

    Odbadrakh, Kh; Nicholson, D. M.; Rusanu, A.; Samolyuk, G. D.; Stoller, R. E.; Zhang, X.-G.; Stocks, G. M.

    2012-12-01

    Classical Molecular Dynamics (MD) simulations characterizing dislocations and radiation damage typically treat 105-107 atoms. First principles techniques employed to understand systems at an atomistic level are not practical for such large systems consisting of millions of atoms. We present an efficient coarse grained (CG) approach to calculate local electronic and magnetic properties of large MD-generated structures from the first principles. Local atomic magnetic moments in crystalline Fe are perturbed by the presence of radiation generated vacancies and interstitials. The effects are most pronounced near the defect cores and decay slowly as the strain field of the defects decrease with distance. We develop the CG technique based on the Locally Self-consistent Multiple Scattering (LSMS) method that exploits the near-sightedness of the electron Green function. The atomic positions were determined by MD with an embedded atom force field. The local moments in the neighborhood of the defect cores are calculated with first-principles based on full local structure information. Atoms in the rest of the system are modeled by representative atoms with approximated properties. The calculations result in local moments near the defect centers with first-principles accuracy, while capturing coarse-grained details of local moments at greater length scales. This CG approach makes these large scale structures amenable to first principles study.

  15. A seismic free field input model for FE-SBFE coupling in time domain

    NASA Astrophysics Data System (ADS)

    Junyi, Yan; Feng, Jin; Yanjie, Xu; Guanglun, Wang; Chuhan, Zhang

    2003-06-01

    A seismic free field input formulation of the coupling procedure of the finite element (FE) and the scaled boundary finite-element (SBFE) is proposed to perform the unbounded soil-structure interaction analysis in time domain. Based on the substructure technique, seismic excitation of the soil-structure system is represented by the free-field motion of an elastic half-space. To reduce the computational effort, the acceleration unit-impulse response function of the unbounded soil is decomposed into two functions; linear and residual. The latter converges to zero and can be truncated as required. With the prescribed tolerance parameter, the balance between accuracy and efficiency of the procedure can be controlled. The validity of the model is verified by the scattering analysis of a hemi-spherical canyon subjected to plane harmonic P, SV and SH wave incidence. Numerical results show that the new procedure is very efficient for seismic problems within a normal range of frequency. The coupling procedure presented herein can be applied to linear and nonlinear earthquake response analysis of practical structures which are built on unbounded soil.

  16. Pairing Strengths for a Two Orbital Model of the Fe-pnictides

    SciTech Connect

    Qi, Xiao-Liang; Raghu, S.; Liu, Chao-Xing; Scalapino, D.J.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-03-25

    Using an RPA approximation, we have calculated the strengths of the singlet and triplet pairing interactions which arise from the exchange of spin and orbital fluctuations for a 2-orbital model of the Fe-pnictide superconductors. When the system is doped with F, the electron pockets become dominant and we find that the strongest pairing occurs in the singlet d-wave pairing and the triplet p-wave pairing channels, which compete closely. The pairing structure in the singlet d-wave channel corresponds to a superposition of near neighbor intra-orbital singlets with a minus sign phase difference between the d{sub xz} and d{sub yz} pairs. The leading pairing configuration in the triplet channel also involves a nearest neighbor intra-orbital pairing. We find that the strengths of both the singlet and triplet pairing grow, with the singlet pairing growing faster, as the onsite Coulomb interaction approaches the value where the S = 1 particle-hole susceptibility diverges.

  17. Monte Carlo study of decorated dislocation loops in FeNiMnCu model alloys

    NASA Astrophysics Data System (ADS)

    Bonny, G.; Terentyev, D.; Zhurkin, E. E.; Malerba, L.

    2014-09-01

    Radiation-induced embrittlement of bainitic steels is the lifetime limiting factor of reactor pressure vessels in existing nuclear light water reactors. The primary mechanism of embrittlement is the obstruction of dislocation motion by nano-metric defects in the bulk of the material due to irradiation. Such features are known to be solute clusters that may be attached to point defect clusters. In this work we study the thermal stability of solute clusters near edge dislocation lines and loops with Burgers vector b = ½[1 1 1] and b = [1 0 0] in FeNiMnCu model alloys by means of Metropolis Monte Carlo simulations. It is concluded that small dislocation loops may indeed act as points for heterogeneous nucleation of solute precipitates in reactor pressure vessel steels and increase their thermodynamic stability up to and above normal reactor operating temperatures. We also found that, in the presence of dislocation-type defects, the Ni content determines the thermodynamic driving force for precipitation, rather than the Mn content.

  18. Phase Field Modeling of Cyclic Austenite-Ferrite Transformations in Fe-C-Mn Alloys

    NASA Astrophysics Data System (ADS)

    Chen, Hao; Zhu, Benqiang; Militzer, Matthias

    2016-06-01

    Three different approaches for considering the effect of Mn on the austenite-ferrite interface migration in an Fe-0.1C-0.5Mn alloy have been coupled with a phase field model (PFM). In the first approach (PFM-I), only long-range C diffusion is considered while Mn is assumed to be immobile during the phase transformations. Both long-range C and Mn diffusions are considered in the second approach (PFM-II). In the third approach (PFM-III), long-range C diffusion is considered in combination with the Gibbs energy dissipation due to Mn diffusion inside the interface instead of solving for long-range diffusion of Mn. The three PFM approaches are first benchmarked with isothermal austenite-to-ferrite transformation at 1058.15 K (785 °C) before considering cyclic phase transformations. It is found that PFM-II can predict the stagnant stage and growth retardation experimentally observed during cycling transformations, whereas PFM-III can only replicate the stagnant stage but not the growth retardation and PFM-I predicts neither the stagnant stage nor the growth retardation. The results of this study suggest a significant role of Mn redistribution near the interface on reducing transformation rates, which should, therefore, be considered in future simulations of austenite-ferrite transformations in steels, particularly at temperatures in the intercritical range and above.

  19. Predictive models of safety based on audit findings: Part 2: Measurement of model validity.

    PubMed

    Hsiao, Yu-Lin; Drury, Colin; Wu, Changxu; Paquet, Victor

    2013-07-01

    Part 1 of this study sequence developed a human factors/ergonomics (HF/E) based classification system (termed HFACS-MA) for safety audit findings and proved its measurement reliability. In Part 2, we used the human error categories of HFACS-MA as predictors of future safety performance. Audit records and monthly safety incident reports from two airlines submitted to their regulatory authority were available for analysis, covering over 6.5 years. Two participants derived consensus results of HF/E errors from the audit reports using HFACS-MA. We adopted Neural Network and Poisson regression methods to establish nonlinear and linear prediction models respectively. These models were tested for the validity of prediction of the safety data, and only Neural Network method resulted in substantially significant predictive ability for each airline. Alternative predictions from counting of audit findings and from time sequence of safety data produced some significant results, but of much smaller magnitude than HFACS-MA. The use of HF/E analysis of audit findings provided proactive predictors of future safety performance in the aviation maintenance field. PMID:23384386

  20. Estimation of uncertainties in geological 3D raster layer models as integral part of modelling procedures

    NASA Astrophysics Data System (ADS)

    Maljers, Denise; den Dulk, Maryke; ten Veen, Johan; Hummelman, Jan; Gunnink, Jan; van Gessel, Serge

    2016-04-01

    applied for DGM Deep proves to be an effective way to (graphically) represent the reliability of the DGM Deep model, although the relative contribution of the various error sources needs further attention. For the DGM Shallow model a cross-validation procedure in a moving window environment has been used to calculate mean deviations and standard errors on a sub-regional scale. Subsequently, these cross validation standard errors have been rescaled to account for local data configuration and clustering. This resulted in standard deviations expressing both regional and local uncertainties. Both workflows are state-of-the-art, form an integral part of the geological modelling and result in reproducible uncertainty values. They can be considered a good starting point for incorporating other errors that contribute to uncertainties of geological 3D raster layer models. For example, the mis-positioning of data used or the error underlying mis-ties at well locations. An additional, perhaps more easy-to-read, parameter that can be calculated to visualize these uncertainties would be the information entropy, as proposed by Wellmann & Regenauer-Lieb (2012). Where a value of 0 means there is no uncertainty, and a value of 1 means there is a high uncertainty. At the moment depth uncertainty information is disseminated through our webportals (www.dinoloket.nl and www.nlog.nl) in an on-line map viewer and as downloadable GIS products.

  1. Radiation transport phenomena and modeling - part A: Codes

    SciTech Connect

    Lorence, L.J.

    1997-06-01

    The need to understand how particle radiation (high-energy photons and electrons) from a variety of sources affects materials and electronics has motivated the development of sophisticated computer codes that describe how radiation with energies from 1.0 keV to 100.0 GeV propagates through matter. Predicting radiation transport is the necessary first step in predicting radiation effects. The radiation transport codes that are described here are general-purpose codes capable of analyzing a variety of radiation environments including those produced by nuclear weapons (x-rays, gamma rays, and neutrons), by sources in space (electrons and ions) and by accelerators (x-rays, gamma rays, and electrons). Applications of these codes include the study of radiation effects on electronics, nuclear medicine (imaging and cancer treatment), and industrial processes (food disinfestation, waste sterilization, manufacturing.) The primary focus will be on coupled electron-photon transport codes, with some brief discussion of proton transport. These codes model a radiation cascade in which electrons produce photons and vice versa. This coupling between particles of different types is important for radiation effects. For instance, in an x-ray environment, electrons are produced that drive the response in electronics. In an electron environment, dose due to bremsstrahlung photons can be significant once the source electrons have been stopped.

  2. Unified Model of the rf Plasma Sheath, Part II

    NASA Astrophysics Data System (ADS)

    Riley, Merle

    1996-10-01

    By developing an approximation to the first integral of the Poisson equation, one can obtain solutions for the current-voltage characteristics of an rf plasma sheath that are valid over the whole range of inertial response of the ions to an imposed rf voltage or current. (M.E.Riley, 1995 GEC, abstract QA5, published in Bull. Am. Phys. Soc., 40, 1587 (1995).) The theory has been shown to adequately reproduce current-voltage characteristics of two extreme cases (M.A. Lieberman, IEEE Trans. Plasma Sci. 16, 638 (1988). A. Metze, D.W. Ernie, and H.J.Oskam, J.Appl.Phys., 60, 3081 (1986).) of ion response. In this work I show the effect of different conventions for connecting the sheath model to the bulk plasma. Modifications of the Mach number and a finite electric field at the Bohm point are natural choices. The differences are examined for a sheath in a high density Ar plasma and are found to be insignificant. A theoretical argument favors the electric field modification. *Work performed at Sandia National Labs and supported by US DoE under contract DE-AC04-94AL85000.

  3. 12 CFR Appendix B to Part 222 - Model Notices of Furnishing Negative Information

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 3 2014-01-01 2014-01-01 false Model Notices of Furnishing Negative... Appendix B to Part 222—Model Notices of Furnishing Negative Information a. Although use of the model... institution properly uses the model notices in this appendix (as applicable). b. A financial institution...

  4. 12 CFR Appendix C to Part 41 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., or meaningful sequence of the language in the model forms. Persons making such extensive revisions... comply with § 41.23(a)(2) of this part. C-1 Model Form for Initial Opt-out Notice (Single-Affiliate... (Single-Affiliate Notice) C-4 Model Form for Renewal Notice (Joint Notice) C-5—Model Form for...

  5. 12 CFR Appendix C to Part 229 - Model Availability Policy Disclosures, Clauses, and Notices; Model Substitute Check Policy...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Model Availability Policy Disclosures, Clauses, and Notices; Model Substitute Check Policy Disclosure and Notices C Appendix C to Part 229 Banks and... OF FUNDS AND COLLECTION OF CHECKS (REGULATION CC) Pt. 229, App. C Appendix C to Part...

  6. 12 CFR Appendix C to Part 229 - Model Availability Policy Disclosures, Clauses, and Notices; Model Substitute Check Policy...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... notices to facilitate compliance with the disclosure and notice requirements of Regulation CC (12 CFR part... OF FUNDS AND COLLECTION OF CHECKS (REGULATION CC) Pt. 229, App. C Appendix C to Part 229—Model... models C-22 through C-25) to make disclosures required by Regulation CC are deemed to be in...

  7. 12 CFR Appendix C to Part 229 - Model Availability Policy Disclosures, Clauses, and Notices; Model Substitute Check Policy...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... notices to facilitate compliance with the disclosure and notice requirements of Regulation CC (12 CFR part... OF FUNDS AND COLLECTION OF CHECKS (REGULATION CC) Pt. 229, App. C Appendix C to Part 229—Model... models C-22 through C-25) to make disclosures required by Regulation CC are deemed to be in...

  8. 12 CFR Appendix C to Part 229 - Model Availability Policy Disclosures, Clauses, and Notices; Model Substitute Check Policy...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... notices to facilitate compliance with the disclosure and notice requirements of Regulation CC (12 CFR part...) AVAILABILITY OF FUNDS AND COLLECTION OF CHECKS (REGULATION CC) Pt. 229, App. C Appendix C to Part 229—Model... models C-22 through C-25) to make disclosures required by Regulation CC are deemed to be in...

  9. 12 CFR Appendix C to Part 229 - Model Availability Policy Disclosures, Clauses, and Notices; Model Substitute Check Policy...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... notices to facilitate compliance with the disclosure and notice requirements of Regulation CC (12 CFR part...) AVAILABILITY OF FUNDS AND COLLECTION OF CHECKS (REGULATION CC) Pt. 229, App. C Appendix C to Part 229—Model... models C-22 through C-25) to make disclosures required by Regulation CC are deemed to be in...

  10. Nanostructure evolution under irradiation of Fe(C)MnNi model alloys for reactor pressure vessel steels

    NASA Astrophysics Data System (ADS)

    Chiapetto, M.; Becquart, C. S.; Domain, C.; Malerba, L.

    2015-06-01

    Radiation-induced embrittlement of bainitic steels is one of the most important lifetime limiting factors of existing nuclear light water reactor pressure vessels. The primary mechanism of embrittlement is the obstruction of dislocation motion produced by nanometric defect structures that develop in the bulk of the material due to irradiation. The development of models that describe, based on physical mechanisms, the nanostructural changes in these types of materials due to neutron irradiation are expected to help to better understand which features are mainly responsible for embrittlement. The chemical elements that are thought to influence most the response under irradiation of low-Cu RPV steels, especially at high fluence, are Ni and Mn, hence there is an interest in modelling the nanostructure evolution in irradiated FeMnNi alloys. As a first step in this direction, we developed sets of parameters for object kinetic Monte Carlo (OKMC) simulations that allow this to be done, under simplifying assumptions, using a "grey alloy" approach that extends the already existing OKMC model for neutron irradiated Fe-C binary alloys [1]. Our model proved to be able to describe the trend in the buildup of irradiation defect populations at the operational temperature of LWR (∼300 °C), in terms of both density and size distribution of the defect cluster populations, in FeMnNi model alloys as compared to Fe-C. In particular, the reduction of the mobility of point-defect clusters as a consequence of the presence of solutes proves to be key to explain the experimentally observed disappearance of detectable point-defect clusters with increasing solute content.

  11. SN 2011fe: A Laboratory for Testing Models of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Chomiuk, Laura

    2013-08-01

    SN 2011fe is the nearest supernova of Type Ia (SN Ia) discovered in the modern multi-wavelength telescope era, and it also represents the earliest discovery of an SN Ia to date. As a normal SN Ia, SN 2011fe provides an excellent opportunity to decipher long-standing puzzles about the nature of SNe Ia. In this review, we summarise the extensive suite of panchromatic data on SN 2011fe and gather interpretations of these data to answer four key questions: (1) What explodes in an SN Ia? (2) How does it explode? (3) What is the progenitor of SN 2011fe? and (4) How accurate are SNe Ia as standardisable candles? Most aspects of SN 2011fe are consistent with the canonical picture of a massive CO white dwarf undergoing a deflagration-to-detonation transition. However, there is minimal evidence for a non-degenerate companion star, so SN 2011fe may have marked the merger of two white dwarfs.

  12. Modelling phosphorus (P), sulfur (S) and iron (Fe) interactions for dynamic simulations of anaerobic digestion processes.

    PubMed

    Flores-Alsina, Xavier; Solon, Kimberly; Kazadi Mbamba, Christian; Tait, Stephan; Gernaey, Krist V; Jeppsson, Ulf; Batstone, Damien J

    2016-05-15

    This paper proposes a series of extensions to functionally upgrade the IWA Anaerobic Digestion Model No. 1 (ADM1) to allow for plant-wide phosphorus (P) simulation. The close interplay between the P, sulfur (S) and iron (Fe) cycles requires a substantial (and unavoidable) increase in model complexity due to the involved three-phase physico-chemical and biological transformations. The ADM1 version, implemented in the plant-wide context provided by the Benchmark Simulation Model No. 2 (BSM2), is used as the basic platform (A0). Three different model extensions (A1, A2, A3) are implemented, simulated and evaluated. The first extension (A1) considers P transformations by accounting for the kinetic decay of polyphosphates (XPP) and potential uptake of volatile fatty acids (VFA) to produce polyhydroxyalkanoates (XPHA) by phosphorus accumulating organisms (XPAO). Two variant extensions (A2,1/A2,2) describe biological production of sulfides (SIS) by means of sulfate reducing bacteria (XSRB) utilising hydrogen only (autolithotrophically) or hydrogen plus organic acids (heterorganotrophically) as electron sources, respectively. These two approaches also consider a potential hydrogen sulfide ( [Formula: see text] inhibition effect and stripping to the gas phase ( [Formula: see text] ). The third extension (A3) accounts for chemical iron (III) ( [Formula: see text] ) reduction to iron (II) ( [Formula: see text] ) using hydrogen ( [Formula: see text] ) and sulfides (SIS) as electron donors. A set of pre/post interfaces between the Activated Sludge Model No. 2d (ASM2d) and ADM1 are furthermore proposed in order to allow for plant-wide (model-based) analysis and study of the interactions between the water and sludge lines. Simulation (A1 - A3) results show that the ratio between soluble/particulate P compounds strongly depends on the pH and cationic load, which determines the capacity to form (or not) precipitation products. Implementations A1 and A2,1/A2,2 lead to a reduction in

  13. Treatment of non-ideality in the multiphase model SPACCIM - Part 1: Model development

    NASA Astrophysics Data System (ADS)

    Rusumdar, A. J.; Wolke, R.; Tilgner, A.; Herrmann, H.

    2015-06-01

    module) is valuable to predict the thermodynamic behavior of complex mixtures of multicomponent atmospheric aerosol particles. First simulations with a detailed chemical mechanism have demonstrated the applicability of SPACCIM-SpactMod. The simulations have implied that the treatment of non-ideality should be mandatory for modeling multiphase chemistry processes in deliquesced particles. The modeled activity coefficients implicate that turnovers of chemical processes in deliquesced particles can be both decreased and increased depending on the particular species involved in the reactions. For key ions, activity coefficients on the order of 0.1-0.8 and a strong dependency on the charge state as well as the RH conditions are modeled implicating a lowered chemical ion processing in concentrated solutions. In contrast, modeled activity coefficients of organic compounds are partly > 1 and suggest the possibility of an increased organic processing. Moreover, the model runs have shown noticeable differences in the pH values calculated with and without consideration of non-ideality. On average, the predicted pH values of the simulations considering non-ideality are -0.27 and -0.44 pH units lower under 90 and 70% RH conditions, respectively. More comprehensive results of detailed SPACCIM-SpactMod studies on the multiphase processing in organic-inorganic mixtures of deliquesced particles are described in a companion paper.

  14. Heterolytic Cleavage of Hydrogen by an Iron Hydrogenase Model: An Fe-H - - - H-N Dihydorgen Bond Characterized by Neutron Diffraction

    SciTech Connect

    Liu, Tianbiao L.; Wang, Xiaoping; Hoffmann, Christina; DuBois, Daniel L.; Bullock, R. Morris

    2014-05-19

    Use of hydrogen as a fuel by [FeFe]-hydrogenase enzymes in nature requires heterolytic cleavage of the H-H bond into a proton (H+) and hydride (H-), a reaction that is also a critical step in homogeneous catalysts for hydrogenation of C=O and C=N bonds. An understanding of the catalytic oxidation of H2 by hydrogenases provides insights into the design of synthetic catalysts that are sought as cost-effective alternatives to the use of the precious metal platinum in fuel cells. Crystallographic studies on the [FeFe]-hydrogenase enzyme were critical to understanding of its reactivity, but the key H-H cleavage step is not readily observed experimentally in natural hydrogenases. Synthetic biomimics have provided evidence for H2 cleavage leading to hydride transfer to the metal and proton transfer to an amine. Limitations on the precise location of hydrogen atoms by x-ray diffraction can be overcome by use of neutron diffraction, though its use is severely limited by the difficulty of obtaining suitable crystals and by the scarcity of neutron sources. Here we show that an iron complex with a pendant amine in the diphosphine ligand cleaves hydrogen heterolytically under mild conditions, leading to [CpC5F4NFeH(PtBu2NtBu2H)]+BArF4-, [PtBu2NtBu2 = 1,5-di(tert-butyl)-3,7-di(tert-butyl)-1,5-diaza-3,7-diphosphacyclooctane; ArF = 3,5-bis(trifluoromethyl)phenyl]. The Fe-H- - - H-N moiety has a strong dihydrogen bond, with a remarkably short H • • • H distance of 1.489(10) Å between the protic N-Hδ+ and hydridic Fe-Hδ-. The structural data for [CpC5F4NFeH(PtBu2NtBu2H)]+ provide a glimpse of how the H-H bond is oxidized or generated in hydrogenase enzymes, with the pendant amine playing a key role as a proton relay. The iron complex [CpC5F4NFeH(PtBu2NtBu2H)]+BArF4- is an electrocatalyst for oxidation of H2 (1 atm) at 22 °C, so the structural data are obtained on a complex that is a functional model for catalysis by [FeFe]-hydrogenase enzymes. This research was supported

  15. 12 CFR Appendix B to Part 230 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Model Clauses and Sample Forms B Appendix B to Part 230 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM TRUTH IN SAVINGS (REGULATION DD) Pt. 230, App. B Appendix B to Part 230—Model Clauses and Sample Forms Table of contents B-1—Model...

  16. Regression Model for Light Weight and Crashworthiness Enhancement Design of Automotive Parts in Frontal CAR Crash

    NASA Astrophysics Data System (ADS)

    Bae, Gihyun; Huh, Hoon; Park, Sungho

    This paper deals with a regression model for light weight and crashworthiness enhancement design of automotive parts in frontal car crash. The ULSAB-AVC model is employed for the crash analysis and effective parts are selected based on the amount of energy absorption during the crash behavior. Finite element analyses are carried out for designated design cases in order to investigate the crashworthiness and weight according to the material and thickness of main energy absorption parts. Based on simulations results, a regression analysis is performed to construct a regression model utilized for light weight and crashworthiness enhancement design of automotive parts. An example for weight reduction of main energy absorption parts demonstrates the validity of a regression model constructed.

  17. Microstructural evolution in NF616 (P92) and Fe-9Cr-0.1C-model alloy under heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Topbasi, Cem; Kaoumi, Djamel; Motta, Arthur T.; Kirk, Mark A.

    2015-11-01

    In this comparative study, in situ investigations of the microstructure evolution in a Fe-9Cr ferritic-martensitic steel, NF616, and a Fe-9Cr-0.1C-model alloy with a similar ferritic-martensitic microstructure have been performed. NF616 and Fe-9Cr-0.1C-model alloy were irradiated to high doses (up to ∼10 dpa) with 1 MeV Kr ions between 50 and 673 K. Defect cluster density increased with dose and saturated in both alloys. The average size of defect clusters in NF616 was constant between 50 and 573 K, on the other hand average defect size increased with dose in Fe-9Cr-0.1C-model alloy around ∼1 dpa. At low temperatures (50-298 K), alignment of small defect clusters resulted in the formation of extensive defects in Fe-9Cr-0.1C-model alloy around ∼2-3 dpa, while similar large defects in NF616 started to form at a high temperature of 673 K around ∼5 dpa. Interaction of defect clusters with the lath boundaries were found to be much more noticeable in Fe-9Cr-0.1C-model alloy. Differences in the microstructural evolution of NF616 and Fe-9Cr-0.1C-model alloy are explained by means of the defect cluster trapping by solute atoms which depends on the solute atom concentrations in the alloys.

  18. Lattice vibration spectra. Part LXXXII. Brucite-type hydroxides M(OH)2 (M = Ca, Mn, Co, Fe, Cd) — IR and Raman spectra, neutron diffraction of Fe(OH)2

    NASA Astrophysics Data System (ADS)

    Lutz, H. D.; Möller, H.; Schmidt, M.

    1994-12-01

    Fe3+-free white rust Fe(O(H,D))2 has been prepared and characterized by X-ray, neutron diffraction, and IR and Raman spectroscopic methods. The crystal structure of Fe(OH)2 (space group Poverline3ml, Z = 1, a = 326.289(1) pm and c = 460.4(1)pm; V = 42.45(1) × 106 pm3) was refined to a final RI = 5.6%. The results of IR and Raman spectra of the brucite-type M(O(H,D))2 (M = Ca, Mn, Fe, Co, Cd) are presented and discussed in terms of (i) assignment of the librational and translational modes, (ii) frequency shifts with respect to MO bond lengths, unit-cell volumes and masses of the atoms involved, and (iii) the nature of the large unit-cell group splittings of the OH stretching modes. Due to different bonding, i.e. more or less covalent, the brucite-type hydroxides can be divided into two groups of M = Ca, Mg, and M = Fe, Co, Ni, and Cd, respectively.

  19. Dynamic mechanical response and a constitutive model of Fe-based high temperature alloy at high temperatures and strain rates.

    PubMed

    Su, Xiang; Wang, Gang; Li, Jianfeng; Rong, Yiming

    2016-01-01

    The effects of strain rate and temperature on the dynamic behavior of Fe-based high temperature alloy was studied. The strain rates were 0.001-12,000 s(-1), at temperatures ranging from room temperature to 800 °C. A phenomenological constitutive model (Power-Law constitutive model) was proposed considering adiabatic temperature rise and accurate material thermal physical properties. During which, the effects of the specific heat capacity on the adiabatic temperature rise was studied. The constitutive model was verified to be accurate by comparison between predicted and experimental results. PMID:27186468

  20. Modeling of Temperature Dependence of Magnetization in TbFe Films — An Atomistic Spin Simulation Study

    NASA Astrophysics Data System (ADS)

    Jiao, Xiankai; Zhang, Zongzhi; Liu, Yaowen

    2016-04-01

    In this paper, we performed spin simulations at atomistic level to study the temperature dependent properties of perpendicularly magnetized TbFe thin films. The crystallographically amorphous feature of TbFe ferrimagnetic alloys is modeled by using a lattice system with disordered site occupation of rare earth (RE) and transition metal (TM) spins. The simulated Curie temperature (TC) is consistent well with the mean-field approximation theory. With the increase of Tb concentration, the TC decreases almost linearly, whereas the magnetization compensation temperature (TM) increases gradually until the TC value is reached. The inter-sublattice exchange coupling strength JTM-RE between the RE and TM atoms can significantly affect TM, but has less impact on TC. With the increase of Tb concentration, the TbFe sample of high JTM-RE exhibits a much faster increase in TM than the sample with low JTM-RE. Moreover, we have tested the simulation code to model the laser pulse induced ultrafast nonequilibrium spin dynamics. As an example, the femto-second pulse laser induced demagnetization and recovery process is clearly reproduced. These features are in a good agreement with the experiments, indicating that the simulation model can capture the basic physics in describing the high temperature dependent magnetic property as well as the ultrafast spin dynamics.

  1. The behavior of Fe3+/∑Fe during partial melting of spinel lherzolite

    NASA Astrophysics Data System (ADS)

    Gaetani, Glenn A.

    2016-07-01

    This study presents an internally consistent model for the behavior of Fe3+/∑Fe during partial melting of spinel lherzolite. The Fe3+/∑Fe ratio for olivine is calculated on the basis of point defect thermodynamics, and the oxidation states of iron in the other solid phases are calculated using Fe3+/Fe2+ distribution between olivine and orthopyroxene, clinopyroxene, or spinel. Conservation of mass is used to relate the Fe3+/Fe2+ ratio of partial melt to the concentrations of Fe3+ and Fe2+ in the initial and residual solids as a function of pressure, temperature, and oxygen fugacity. Results from isobaric batch melting calculations demonstrate that the Fe3+/∑Fe ratio of the partial melt decreases with increasing melt fraction. Conversely, the Fe3+/∑Fe ratio of the partial melt increases with increasing melt fraction during decompression batch melting. The relative oxygen fugacity of the upper mantle depends on both the oxidation state of iron and mantle potential temperature. Results from incremental decompression melting calculations in which 1% melt is produced for each 100 MPa of decompression and then removed from the residual solid indicate that relative oxygen fugacity calculated from the oxidation state of iron in basaltic glass does not represent a unique value for the oceanic upper mantle but, rather, reflects conditions in the lower portion of the melting regime. A 100 °C change in mantle potential temperature produces a change in relative oxygen fugacity of ∼0.8 log units, similar to the global range inferred from mid-ocean ridge basalt glasses. It is necessary, therefore, to compare relative oxygen fugacity calculated from basaltic glass with proxies for potential temperature before drawing conclusions on heterogeneity of the oxidation state of iron in the oceanic upper mantle. Results from model calculations also suggest that the sub-arc mantle is intrinsically more oxidizing than the oceanic mantle because it is cooler. The global correlation

  2. Characterisation of Cr, Si and P distribution at dislocations and grain-boundaries in neutron irradiated Fe-Cr model alloys of low purity

    NASA Astrophysics Data System (ADS)

    Kuksenko, V.; Pareige, C.; Genevois, C.; Pareige, P.

    2013-03-01

    Segregations at some dislocations and grain boundaries in Fe-5%Cr, Fe-9%Cr and Fe-12%Cr model alloys of low purity after neutron irradiation at 300 °C up to 0.6 dpa have been analyzed with atom probe tomography. All dislocation lines and low- and high-angle grain boundaries (GBs) which have been observed were enriched with Cr, Si and P. The segregations reveal the different dislocation structures associated to different type of analysed GBs. Cr and Si atoms were found to be nonhomogenously distributed around the dislocation cores because of the non isotropic stress field induced by edge dislocation lines. Concerning GBs, precipitate free zones (PFZs) are exhibited around the planar defects which were analysed in Fe-9%Cr and Fe-12%Cr model alloys. These PFZ are size dependant with the nominal level of Cr.

  3. Multiscale modeling of the influence of Fe content in a Al-Si-Cu alloy on the size distribution of intermetallic phases and micropores

    NASA Astrophysics Data System (ADS)

    Wang, Junsheng; Li, Mei; Allison, John; Lee, Peter D.

    2010-03-01

    A multiscale model was developed to simulate the formation of Fe-rich intermetallics and pores in quaternary Al-Si-Cu-Fe alloys. At the microscale, the multicomponent diffusion equations were solved for multiphase (liquid-solid-gas) materials via a finite difference framework to predict microstructure formation. A fast and robust decentered plate algorithm was developed to simulate the strong anisotropy of the solid/liquid interfacial energy for the Fe-rich intermetallic phase. The growth of porosity was controlled by local pressure drop due to solidification and interactions with surrounding solid phases, in addition to hydrogen diffusion. The microscale model was implemented as a subroutine in a commercial finite element package, producing a coupled multiscale model. This allows the influence of varying casting conditions on the Fe-rich intermetallics, the pores, and their interactions to be predicted. Synchrotron x-ray tomography experiments were performed to validate the model by comparing the three-dimensional morphology and size distribution of Fe-rich intermetallics as a function of Fe content. Large platelike Fe-rich β intermetallics were successfully simulated by the multiscale model and their influence on pore size distribution in shape castings was predicted as a function of casting conditions.

  4. Simplified electrochemical multi-particle model for LiFePO4 cathodes in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Mastali Majdabadi, Mehrdad; Farhad, Siamak; Farkhondeh, Mohammad; Fraser, Roydon A.; Fowler, Michael

    2015-02-01

    A simplified physics-based model is developed to predict the performance of an LiFePO4 cathode at various operating and design conditions. Newman's full-order porous-electrode model is simplified using polynomial approximations for electrolyte variables at the electrode-level while a multi-particle model featuring variable solid-state diffusivity is employed at the particle level. The computational time of this reduced-order model is decreased by almost one order of magnitude compared to the full-order model without sacrificing the accuracy of the results. The model is general and can be used to expedite the simulation of any composite electrode with active-material particles of non-uniform properties (e.g., size, contact resistance, material chemistry etc.). In a broader perspective, this model is of practical value for electric vehicle power train simulations and battery management systems.

  5. 12 CFR Appendix H to Part 1026 - Closed-End Model Forms and Clauses

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 8 2012-01-01 2012-01-01 false Closed-End Model Forms and Clauses H Appendix H...) Pt. 1026, App. H Appendix H to Part 1026—Closed-End Model Forms and Clauses H-1Credit Sale Model Form (§ 1026.18) H-2Loan Model Form (§ 1026.18) H-3Amount Financed Itemization Model Form (§ 1026.18(c))...

  6. 12 CFR Appendix H to Part 1026 - Closed-End Model Forms and Clauses

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 8 2013-01-01 2013-01-01 false Closed-End Model Forms and Clauses H Appendix H...) Pt. 1026, App. H Appendix H to Part 1026—Closed-End Model Forms and Clauses H-1Credit Sale Model Form (§ 1026.18) H-2Loan Model Form (§ 1026.18) H-3Amount Financed Itemization Model Form (§ 1026.18(c))...

  7. 12 CFR Appendix B to Part 1030 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 8 2013-01-01 2013-01-01 false Model Clauses and Sample Forms B Appendix B to.... 1030, App. B Appendix B to Part 1030—Model Clauses and Sample Forms 1. Modifications. Institutions that modify the model clauses will be deemed in compliance as long as they do not delete required...

  8. 12 CFR Appendix C to Part 239 - Mutual Holding Company Model Bylaws

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 4 2013-01-01 2013-01-01 false Mutual Holding Company Model Bylaws C Appendix C to Part 239 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL...—Mutual Holding Company Model Bylaws MODEL BYLAWS FOR MUTUAL HOLDING COMPANIES The term “trustees” may...

  9. 12 CFR Appendix B to Part 1030 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 9 2014-01-01 2014-01-01 false Model Clauses and Sample Forms B Appendix B to.... 1030, App. B Appendix B to Part 1030—Model Clauses and Sample Forms 1. Modifications. Institutions that modify the model clauses will be deemed in compliance as long as they do not delete required...

  10. 31 CFR Appendix A to Part 212 - Model Notice to Account Holder

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 2 2012-07-01 2012-07-01 false Model Notice to Account Holder A... CONTAINING FEDERAL BENEFIT PAYMENTS Pt. 212, App. A Appendix A to Part 212—Model Notice to Account Holder A financial institution may use the following model notice to meet the requirements of § 212.7. Although...

  11. 12 CFR Appendix B to Part 1022 - Model Notices of Furnishing Negative Information

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 8 2013-01-01 2013-01-01 false Model Notices of Furnishing Negative... REPORTING (REGULATION V) Pt. 1022, App. B Appendix B to Part 1022—Model Notices of Furnishing Negative Information a. Although use of the model notices is not required, a financial institution that is subject...

  12. 31 CFR Appendix A to Part 212 - Model Notice to Account Holder

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 2 2013-07-01 2013-07-01 false Model Notice to Account Holder A... CONTAINING FEDERAL BENEFIT PAYMENTS Pt. 212, App. A Appendix A to Part 212—Model Notice to Account Holder A financial institution may use the following model notice to meet the requirements of § 212.7. Although...

  13. 12 CFR Appendix C to Part 239 - Mutual Holding Company Model Bylaws

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 4 2012-01-01 2012-01-01 false Mutual Holding Company Model Bylaws C Appendix C to Part 239 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL...—Mutual Holding Company Model Bylaws MODEL BYLAWS FOR MUTUAL HOLDING COMPANIES The term “trustees” may...

  14. 12 CFR Appendix B to Part 230 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 4 2014-01-01 2014-01-01 false Model Clauses and Sample Forms B Appendix B to... SYSTEM (CONTINUED) TRUTH IN SAVINGS (REGULATION DD) Pt. 230, App. B Appendix B to Part 230—Model Clauses and Sample Forms Table of contents B-1—Model Clauses for Account Disclosures (Section 230.4(b))...

  15. 12 CFR Appendix B to Part 1022 - Model Notices of Furnishing Negative Information

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 8 2012-01-01 2012-01-01 false Model Notices of Furnishing Negative... REPORTING (REGULATION V) Pt. 1022, App. B Appendix B to Part 1022—Model Notices of Furnishing Negative Information a. Although use of the model notices is not required, a financial institution that is subject...

  16. 12 CFR Appendix B to Part 230 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 4 2012-01-01 2012-01-01 false Model Clauses and Sample Forms B Appendix B to... SYSTEM (CONTINUED) TRUTH IN SAVINGS (REGULATION DD) Pt. 230, App. B Appendix B to Part 230—Model Clauses and Sample Forms Table of contents B-1—Model Clauses for Account Disclosures (Section 230.4(b))...

  17. 12 CFR Appendix B to Part 230 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 4 2013-01-01 2013-01-01 false Model Clauses and Sample Forms B Appendix B to... SYSTEM (CONTINUED) TRUTH IN SAVINGS (REGULATION DD) Pt. 230, App. B Appendix B to Part 230—Model Clauses and Sample Forms Table of contents B-1—Model Clauses for Account Disclosures (Section 230.4(b))...

  18. 31 CFR Appendix A to Part 212 - Model Notice to Account Holder

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 2 2011-07-01 2011-07-01 false Model Notice to Account Holder A... CONTAINING FEDERAL BENEFIT PAYMENTS Pt. 212, App. A Appendix A to Part 212—Model Notice to Account Holder A financial institution may use the following model notice to meet the requirements of § 212.7. Although...

  19. 12 CFR Appendix C to Part 239 - Mutual Holding Company Model Bylaws

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 4 2014-01-01 2014-01-01 false Mutual Holding Company Model Bylaws C Appendix C to Part 239 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL...—Mutual Holding Company Model Bylaws MODEL BYLAWS FOR MUTUAL HOLDING COMPANIES The term “trustees” may...

  20. Characterization of the Fe Site in Iron-Sulfur-Cluster-Free Hydrogenase (Hmd) and of a Model Compound via Nuclear Resonance Vibrational Spectroscopy (NRVS)

    PubMed Central

    Guo, Yisong; Wang, Hongxin; Xiao, Yuming; vogt, Sonja; Shima, Seigo; Volkers, Phillip I.; Pelmentschikov, Vladimir; Alp, Ercan E.; Sturhahn, Wolfgang; Yada, Yoshitaka

    2009-01-01

    We have used 57Fe nuclear resonance vibrational spectroscopy (NRVS) to study the iron site in the iron-sulfur-cluster-free hydrogenase Hmd from the methanogenic archaeon Methanothermobacter marburgensis. The spectra have been interpreted by comparison with a cis-(CO)2-ligated Fe model compound, Fe(S2C2H4)(CO)2(PMe3)2, as well as by normal mode simulations of plausible active site structures. For this model complex, normal mode analyses both from an optimized Urey-Bradley force field and from complementary density functional theory (DFT) calculations produced consistent results. Previous IR spectroscopic studies found strong CO stretching modes at 1944 and 2011 cm−1, interpreted as evidence for cis-Fe(CO)2 ligation. The NRVS data provide further insight into the dynamics of the Fe site, revealing Fe-CO stretch and Fe-CO bend modes at 494, 562, 590, and 648 cm−1, consistent with the proposed cis-Fe(CO)2 ligation. The NRVS also reveals a band assigned to Fe-S stretching motion at ~311 cm−1, and another reproducible feature at ~380 cm−1. The 57Fe partial vibrational densities of states (PVDOS) for Hmd can be reasonably well simulated by a normal mode analysis based on a Urey-Bradley force field for a 5-coordinate cis-(CO)2-ligated Fe site with additional cysteine, water, and pyridone cofactor ligands. A final interpretation of the Hmd NRVS data, including DFT analysis, awaits a 3-dimensional structure for the active site. PMID:18407624

  1. A process model for the microstructure evolution in ductile cast iron. Part 1: The model

    SciTech Connect

    Onsoeien, M.I.; Gundersen, O.; Grong, O.; Skaland, T.

    1999-04-01

    In the present investigation, the multiple phase changes occurring during solidification and subsequent cooling of near-eutectic ductile cast iron have been modeled using the internal state variable approach. According to this formalism, the microstructure evolution is captured mathematically in terms of differential variation of the primary state variables with time for each of the relevant mechanisms. Separate response equations have then been developed to convert the current values of the state variables into equivalent volume fractions of constituent phases utilizing the constraints provided by the phase diagram. The results may conveniently be represented in the form of C curves and process diagrams to illuminate how changes in alloy composition, graphite nucleation potential, and thermal program affect the microstructure evolution at various stages of the process. The model can readily be implemented in a dedicated numerical code for the thermal field in real castings and used as a guiding tool in design of new treatment alloys for ductile cast irons. An illustration of this is given in an accompanying article (Part 2).

  2. Application of artificial intelligence (AI) concepts to the development of space flight parts approval model

    NASA Technical Reports Server (NTRS)

    Krishnan, G. S.

    1997-01-01

    A cost effective model which uses the artificial intelligence techniques in the selection and approval of parts is presented. The knowledge which is acquired from the specialists for different part types are represented in a knowledge base in the form of rules and objects. The parts information is stored separately in a data base and is isolated from the knowledge base. Validation, verification and performance issues are highlighted.

  3. The comparison of different approaches to the modeling of the structural properties σ-phase of Fe-Cr system

    NASA Astrophysics Data System (ADS)

    Udovsky, A. L.; Kupavtsev, M. V.

    2016-04-01

    The three- sub-lattice model (3SLM) for description of atom's distribution of two components with different coordination numbers (12, 14 and 15), into σ-phase structure depended on composition and temperature is depictured in this paper. Energetic parameters of 3SLM were calculated by fitting procedure fixed to results obtained by ab-initio calculations conducted for paramagnetic states of differently ordered complexes stayed at the sigma- phase's crystal structure for Fe-Cr system at 0 K. Respective algorithm and computer program have allowed to calculate an atom distribution of components upon the sub-lattices of σ-phase at 300 - 1100 K. The temperature dependences of filling atoms on the model three sub-lattices for alloys compositions 40, 50 and 60 at. % Fe was calculated. There is satisfactory agreement between calculated results and the experimental data obtained by neutron and structural research methods. The equilibrium between BCC solutions and σ- phase of Fe-Cr system was calculated. The satisfactory consent of results of calculation with experimental data for education temperature σ- phases from BCC- solution and some divergences with experiments is received at 800 K.

  4. Evaluation on the Effect of Composition on Radiation Hardening and Embrittlement in Model FeCrAl Alloys

    SciTech Connect

    Field, Kevin G.; Briggs, Samuel A.; Edmondson, Philip; Hu, Xunxiang; Littrell, Kenneth C.; Howard, Richard; Parish, Chad M.; Yamamoto, Yukinori

    2015-09-18

    This report details the findings of post-radiation mechanical testing and microstructural characterization performed on a series of model and commercial FeCrAl alloys to assist with the development of a cladding technology with enhanced accident tolerance. The samples investigated include model alloys with simple ferritic grain structure and two commercial alloys with minor solute additions. These samples were irradiated in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) up to nominal doses of 7.0 dpa near or at Light Water Reactor (LWR) relevant temperatures (300-400 C). Characterization included a suite of techniques including small angle neutron scattering (SANS), atom probe tomography (APT), and transmission based electron microscopy techniques. Mechanical testing included tensile tests at room temperature on sub-sized tensile specimens. The goal of this work was to conduct detailed characterization and mechanical testing to begin establishing empirical and/or theoretical structure-property relationships for radiation-induced hardening and embrittlement in the FeCrAl alloy class. Development of such relationships will provide insight on the performance of FeCrAl alloys in an irradiation environment and will enable further development of the alloy class for applications within a LWR environment. A particular focus was made on establishing trends, including composition and radiation dose. The report highlights in detail the pertinent findings based on this work. This report shows that radiation hardening in the alloys is primarily composition dependent due to the phase separation in the high-Cr FeCrAl alloys. Other radiation induced/enhanced microstructural features were less dependent on composition and when observed at low number densities, were not a significant contributor to the observed mechanical responses. Pre-existing microstructure in the alloys was found to be important, with grain boundaries and pre-existing dislocation

  5. Effect of electron- and neutron-irradiation on Fe-Cu model alloys studied by positron annihilation spectroscopy

    NASA Astrophysics Data System (ADS)

    Nagai, Y.; Takadate, K.; Tang, Z.; Ohkubo, H.; Sunaga, H.; Takizawa, H.; Hasegawa, M.

    2011-01-01

    Electron- and neutron-irradiation effects on dilute Fe-Cu model alloys of nuclear reactor pressure vessel steels are studied by positron annihilation spectroscopy. We have found that, not only by high-dose neutron-irradiation but also by low-dose electron-irradiation, the aggregation of Cu atoms and vacancies takes place and the ultrafine Cu precipitates are formed after post-irradiation annealing at 400°C. In spite of large difference in the irradiation doses between the electron- and the neutron-irradiated samples, no significant difference is observed in the isochronal annealing behaviour above 400°C of positron annihilation and micro-hardness, indicating that small amount of extra vacancies enhance the aggregation of Cu atoms in Fe during the annealing-out process of the vacancies.

  6. AERMOD: A DISPERSION MODEL FOR INDUSTRIAL SOURCE APPLICATIONS PART II: MODEL PERFORMANCE AGAINST 17 FIELD STUDY DATABASES

    EPA Science Inventory

    The formulations of the AMS/EPA Regulatory Model Improvement Committee's applied air dispersion model (AERMOD) are described. This is the second in a series of three articles. Part I describes the model's methods for characterizing the atmospheric boundary layer and complex ter...

  7. 12 CFR Appendix C to Part 222 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Model Forms for Opt-Out Notices C Appendix C to Part 222 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM FAIR CREDIT REPORTING (REGULATION V) Pt. 222, App. C Appendix C to Part 222—Model Forms for Opt-Out Notices a. Although use of the...

  8. 12 CFR Appendix G to Part 226 - Open-End Model Forms and Clauses

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Open-End Model Forms and Clauses G Appendix G to Part 226 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM TRUTH IN LENDING (REGULATION Z) Pt. 226, App. G Appendix G to Part 226—Open-End Model Forms and Clauses G-1Balance-Computation...

  9. 12 CFR Appendix G to Part 226 - Open-End Model Forms and Clauses

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 3 2011-01-01 2011-01-01 false Open-End Model Forms and Clauses G Appendix G to Part 226 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM TRUTH IN LENDING (REGULATION Z) Pt. 226, App. G Appendix G to Part 226—Open-End Model Forms and Clauses G-1Balance Computation...

  10. Surface complexation modeling of Fe3O4-H+ and Mg(II) sorption onto maghemite and magnetite.

    PubMed

    Jolsterå, Rickard; Gunneriusson, Lars; Holmgren, Allan

    2012-11-15

    The surface acid/base properties of magnetite (Fe(3)O(4)) particles and the sorption of Mg(2+) onto magnetite and maghemite (γ-Fe(2)O(3)) have been studied using high precision potentiometric titrations, batch experiments, and zeta potential measurements. The acid/base properties of magnetite were found to be very similar to maghemite except for the difference in surface site density, N(s) (sites nm(-2)), 1.50±0.08 for magnetite, and 0.99±0.05 for maghemite. The experimental proton exchange of the magnetite surface increased from pH 10 and above, indicating dissolution/transformation reactions of magnetite at alkaline conditions. Thus, magnetite with its Fe(II) content proved to be less stable toward dissolution in comparison with pure Fe(III) oxides also at high pH values. Three different ratios between surface sites and added Mg(2+) were used in the sorption experiments viz. 0.5, 1, and 2Mg(2+)site(-1). Surface complexation modeling of the Mg(2+) sorption onto maghemite and magnetite was restricted to pH conditions where the interference from Mg(OH)(2)(s) precipitation could be ruled out. The model calculations showed that Mg(2+) sorb onto the magnetite and maghemite surfaces as a mixture of mono- or bidentate surface complexes at 0.5Mg(2+)site(-1) and as monodentate complexes at 1 and 2Mg(2+)site(-1) conditions. Mg(2+) was also found to adsorb more readily at the maghemite surfaces in comparison with magnetite surfaces. For experiments with excess Mg(2+) relative to the number of surface sites, the calculations suggested the formation of polynuclear surface complexes on maghemite. PMID:22889624

  11. Synthesis of magnetic γ-Fe2O3-based nanomaterial for ultrasonic assisted dyes adsorption: Modeling and optimization.

    PubMed

    Asfaram, Arash; Ghaedi, Mehrorang; Hajati, Shaaker; Goudarzi, Alireza

    2016-09-01

    γ-Fe2O3 nanoparticles were synthesized and loaded on activated carbon. The prepared nanomaterial was characterized by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transforms infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The γ-Fe2O3 nanoparticle-loaded activated carbon (γ-Fe2O3-NPs-AC) was used as novel adsorbent for the ultrasonic-assisted removal of methylene blue (MB) and malachite green (MG). Response surface methodology and artificial neural network were applied to model and optimize the adsorption of the MB and MG in their individual and binary solutions followed by the investigation on adsorption isotherm and kinetics. The individual effects of parameters such as pH, mass of adsorbent, ultrasonication time as well as MB and MG concentrations in addition to the effects of their possible interactions on the adsorption process were investigated. The numerical optimization revealed that the optimum adsorption (>99.5% for each dye) is obtained at 0.02g, 15mgL(-1), 4min and 7.0 corresponding to the adsorbent mass, each dye concentration, sonication time and pH, respectively. The Freundlich, Langmuir, Temkin and Dubinin-Radushkevich isotherms were studied. The Langmuir was found to be most applicable isotherm which predicted maximum monolayer adsorption capacities of 195.55 and 207.04mgg(-1) for the adsorption of MB and MG, respectively. The pseudo-second order model was found to be applicable for the adsorption kinetics. Blank experiments (without any adsorbent) were run to investigate the possible degradation of the dyes studied in presence of ultrasonication. No dyes degradation was observed. PMID:27150788

  12. A General Reversible Hereditary Constitutive Model. Part 2; Application to a Titanium Alloy

    NASA Technical Reports Server (NTRS)

    Arnold, S. M.; Saleeb, A. F.; Castelli, M. G.

    1997-01-01

    Given the mathematical framework and specific viscoelastic model in Part 1 our primary goal in this second part is focused on model characterization and assessment for the specific titanium alloy, TIMETAL 21S. The model is motivated by experimental evidence suggesting the presence of significant rate/time effects in the so-called quasilinear, reversible, material response range. An explanation of the various experiments performed and their corresponding results are also included. Finally, model correlations and predictions are presented for a wide temperature range.

  13. Mathematical modelling of part voltage and weld current in resistance welders

    SciTech Connect

    Destefan, D.E.

    1990-09-11

    A mathematical model is presented to describe the part voltage and weld current that occur in a single-phase resistance welder. Developing an accurate model of part voltage and current is the first step toward understanding instrumentation, testing, calibration, and measurement requirements. Measurement requirements for dynamic part resistance, calculated from these basic process variables, can ultimately be determined using this analysis. This model utilizes electrical characteristics of the welder, power system, and parts, as well as geometric parameters of voltage-sensing wires to describe the resultant time functions. The complete equivalent circuit involves many resistive and inductive components in the welder primary and secondary circuits. These components are reduced to a simple equivalent circuit to obtain a closed-form solution for part voltage and weld current time functions. Actual measurements were acquired from a welder using a constant resistance load to verify accuracy of the model. Accuracy of the model is estimated to be within the measurement uncertainty and is, in general, approximately {plus minus}3% for current and {plus minus}5% for part voltage. Pertinent limitations of the model's accuracy and range of applications are also discussed briefly. 28 refs., 10 figs.

  14. COLLOIDAL FE2O3 TRANSPORT STUDIES IN LABORATORY MODEL SYSTEMS USING SHALLOW AQUIFER MATERIAL

    EPA Science Inventory

    The stability and transport of radio-labeled Fe2O3 colloids were studied using laboratory batch and column techniques. ore material collected from a shallow sand and gravel aquifer near Globe, Arizona was used as the column matrix material. scintillation counting and laser light ...

  15. SEM-EBSD based Realistic Modeling and Crystallographic Homogenization FE Analyses of LDH Formability Tests

    NASA Astrophysics Data System (ADS)

    Kuramae, Hiroyuki; Ngoc Tam, Nguyen; Nakamura, Yasunori; Sakamoto, Hidetoshi; Morimoto, Hideo; Nakamachi, Eiji

    2007-05-01

    Homogenization algorithm is introduced to the elastic/crystalline viscoplastic finite element (FE) procedure to develop multi-scale analysis code to predict the formability of sheet metal in macro scale, and simultaneously the crystal texture and hardening evolutions in micro scale. The isotropic and kinematical hardening lows are employed in the crystalline plasticity constitutive equation. For the multi-scale structure, two scales are considered. One is a microscopic polycrystal structure and the other a macroscopic elastic plastic continuum. We measure crystal morphologies by using the scanning electron microscope (SEM) with electron back scattered diffraction (EBSD), and define a three dimensional representative volume element (RVE) of micro ploycrystal structure, which satisfy the periodicity condition of crystal orientation distribution. Since nonlinear multi-scale FE analysis requires large computation time, development of parallel computing technique is needed. To realize the parallel analysis on PC cluster system, the dynamic explicit FE formulations are employed. Applying the domain partitioning technique to FE mesh of macro continuum, homogenized stresses based on micro crystal structures are computed in parallel without solving simultaneous linear equation. The parallel FEM code is applied to simulate the limit dome height (LDH) test problem and hemispherical cup deep drawing problem of aluminum alloy AL6022, mild steel DQSK, high strength steel HSLA, and dual phase steel DP600 sheet metals. The localized distribution of thickness strain and the texture evolution are obtained.

  16. 12 CFR Appendix B to Part 230 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 3 2011-01-01 2011-01-01 false Model Clauses and Sample Forms B Appendix B to... SYSTEM TRUTH IN SAVINGS (REGULATION DD) Pt. 230, App. B Appendix B to Part 230—Model Clauses and Sample Forms Table of contents B-1—Model Clauses for Account Disclosures (Section 230.4(b)) B-2—Model...

  17. 12 CFR Appendix B to Part 1030 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 9 2014-01-01 2014-01-01 false Model Clauses and Sample Forms B Appendix B to.... 1030, App. B Appendix B to Part 1030—Model Clauses and Sample Forms Table of Contents B-1—Model Clauses for Account Disclosures (Section 1030.4(b)) B-2—Model Clauses for Change in Terms (Section...

  18. 12 CFR Appendix C to Part 222 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 3 2014-01-01 2014-01-01 false Model Forms for Opt-Out Notices C Appendix C to... SYSTEM (CONTINUED) FAIR CREDIT REPORTING (REGULATION V) Pt. 222, App. C Appendix C to Part 222—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms...

  19. 12 CFR Appendix C to Part 1022 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 8 2013-01-01 2013-01-01 false Model Forms for Opt-Out Notices C Appendix C to...) Pt. 1022, App. C Appendix C to Part 1022—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms in this appendix (as applicable) complies with...

  20. 12 CFR Appendix H to Part 226 - Closed-End Model Forms and Clauses

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Closed-End Model Forms and Clauses H Appendix H... RESERVE SYSTEM TRUTH IN LENDING (REGULATION Z) Pt. 226, App. H Appendix H to Part 226—Closed-End Model Forms and Clauses H-1—Credit Sale Model Form (§ 226.18) H-2—Loan Model Form (§ 226.18)...

  1. 12 CFR Appendix C to Part 334 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 5 2012-01-01 2012-01-01 false Model Forms for Opt-Out Notices C Appendix C to... POLICY FAIR CREDIT REPORTING Pt. 334, App. C Appendix C to Part 334—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms in this Appendix (as...

  2. 12 CFR Appendix C to Part 717 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 7 2012-01-01 2012-01-01 false Model Forms for Opt-Out Notices C Appendix C to... FAIR CREDIT REPORTING Pt. 717, App. C Appendix C to Part 717—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms in this appendix (as...

  3. 12 CFR Appendix H to Part 226 - Closed-End Model Forms and Clauses

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 3 2011-01-01 2011-01-01 false Closed-End Model Forms and Clauses H Appendix H... RESERVE SYSTEM TRUTH IN LENDING (REGULATION Z) Pt. 226, App. H Appendix H to Part 226— Closed-End Model Forms and Clauses H-1Credit Sale Model Form (§ 226.18) H-2Loan Model Form (§ 226.18) H-3Amount...

  4. 12 CFR Appendix C to Part 571 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 5 2011-01-01 2011-01-01 false Model Forms for Opt-Out Notices C Appendix C to... REPORTING Pt. 571, App. C Appendix C to Part 571—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms in this Appendix (as applicable) complies with...

  5. 12 CFR Appendix C to Part 222 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 3 2011-01-01 2011-01-01 false Model Forms for Opt-Out Notices C Appendix C to... SYSTEM FAIR CREDIT REPORTING (REGULATION V) Pt. 222, App. C Appendix C to Part 222—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms in...

  6. 12 CFR Appendix B to Part 1030 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 8 2012-01-01 2012-01-01 false Model Clauses and Sample Forms B Appendix B to.... 1030, App. B Appendix B to Part 1030—Model Clauses and Sample Forms Table of Contents B-1—Model Clauses for Account Disclosures (Section 1030.4(b)) B-2—Model Clauses for Change in Terms (Section...

  7. 12 CFR Appendix H to Part 226 - Closed-End Model Forms and Clauses

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 3 2012-01-01 2012-01-01 false Closed-End Model Forms and Clauses H Appendix H... RESERVE SYSTEM TRUTH IN LENDING (REGULATION Z) Pt. 226, App. H Appendix H to Part 226— Closed-End Model Forms and Clauses H-1Credit Sale Model Form (§ 226.18) H-2Loan Model Form (§ 226.18) H-3Amount...

  8. 12 CFR Appendix C to Part 41 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 1 2011-01-01 2011-01-01 false Model Forms for Opt-Out Notices C Appendix C to... Pt. 41, App. C Appendix C to Part 41—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms in this appendix (as applicable) complies with...

  9. 12 CFR Appendix C to Part 571 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 6 2012-01-01 2012-01-01 false Model Forms for Opt-Out Notices C Appendix C to... REPORTING Pt. 571, App. C Appendix C to Part 571—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms in this Appendix (as applicable) complies with...

  10. 12 CFR Appendix C to Part 717 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Model Forms for Opt-Out Notices C Appendix C to... FAIR CREDIT REPORTING Pt. 717, App. C Appendix C to Part 717—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms in this appendix (as...

  11. 12 CFR Appendix C to Part 1022 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 8 2012-01-01 2012-01-01 false Model Forms for Opt-Out Notices C Appendix C to...) Pt. 1022, App. C Appendix C to Part 1022—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms in this appendix (as applicable) complies with...

  12. 12 CFR Appendix C to Part 222 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 3 2012-01-01 2012-01-01 false Model Forms for Opt-Out Notices C Appendix C to... SYSTEM FAIR CREDIT REPORTING (REGULATION V) Pt. 222, App. C Appendix C to Part 222—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms in...

  13. 12 CFR Appendix B to Part 1030 - Model Clauses and Sample Forms

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 8 2013-01-01 2013-01-01 false Model Clauses and Sample Forms B Appendix B to.... 1030, App. B Appendix B to Part 1030—Model Clauses and Sample Forms Table of Contents B-1—Model Clauses for Account Disclosures (Section 1030.4(b)) B-2—Model Clauses for Change in Terms (Section...

  14. 12 CFR Appendix C to Part 571 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Model Forms for Opt-Out Notices C Appendix C to... REPORTING Pt. 571, App. C Appendix C to Part 571—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms in this Appendix (as applicable) complies with...

  15. 12 CFR Appendix C to Part 41 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 1 2013-01-01 2013-01-01 false Model Forms for Opt-Out Notices C Appendix C to... Pt. 41, App. C Appendix C to Part 41—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms in this appendix (as applicable) complies with...

  16. 12 CFR Appendix C to Part 334 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 4 2011-01-01 2011-01-01 false Model Forms for Opt-Out Notices C Appendix C to... POLICY FAIR CREDIT REPORTING Pt. 334, App. C Appendix C to Part 334—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms in this Appendix (as...

  17. 12 CFR Appendix C to Part 717 - Model Forms for Opt-Out Notices

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 6 2011-01-01 2011-01-01 false Model Forms for Opt-Out Notices C Appendix C to... FAIR CREDIT REPORTING Pt. 717, App. C Appendix C to Part 717—Model Forms for Opt-Out Notices a. Although use of the model forms is not required, use of the model forms in this appendix (as...

  18. Modelling the Peak Elongation of Nylon6 and Fe Powder Based Composite Wire for FDM Feedstock Filament

    NASA Astrophysics Data System (ADS)

    Garg, Harish Kumar; Singh, Rupinder

    2016-06-01

    In the present work, to increase the application domain of fused deposition modelling (FDM) process, Nylon6-Fe powder based composite wire has been prepared as feed stock filament. Further for smooth functioning of feed stock filament without any change in the hardware and software of the commercial FDM setup, the mechanical properties of the newly prepared composite wire must be comparable/at par to the existing material i.e. ABS, P-430. So, keeping this in consideration; an effort has been made to model the peak elongation of in house developed feedstock filament comprising of Nylon6 and Fe powder (prepared on single screw extrusion process) for commercial FDM setup. The input parameters of single screw extruder (namely: barrel temperature, temperature of the die, speed of the screw, speed of the winding machine) and rheological property of material (melt flow index) has been modelled with peak elongation as the output by using response surface methodology. For validation of model the result of peak elongation obtained from the model equation the comparison was made with the results of actual experimentation which shows the variation of ±1 % only.

  19. Transient PVT measurements and model predictions for vessel heat transfer. Part II.

    SciTech Connect

    Felver, Todd G.; Paradiso, Nicholas Joseph; Winters, William S., Jr.; Evans, Gregory Herbert; Rice, Steven F.

    2010-07-01

    Part I of this report focused on the acquisition and presentation of transient PVT data sets that can be used to validate gas transfer models. Here in Part II we focus primarily on describing models and validating these models using the data sets. Our models are intended to describe the high speed transport of compressible gases in arbitrary arrangements of vessels, tubing, valving and flow branches. Our models fall into three categories: (1) network flow models in which flow paths are modeled as one-dimensional flow and vessels are modeled as single control volumes, (2) CFD (Computational Fluid Dynamics) models in which flow in and between vessels is modeled in three dimensions and (3) coupled network/CFD models in which vessels are modeled using CFD and flows between vessels are modeled using a network flow code. In our work we utilized NETFLOW as our network flow code and FUEGO for our CFD code. Since network flow models lack three-dimensional resolution, correlations for heat transfer and tube frictional pressure drop are required to resolve important physics not being captured by the model. Here we describe how vessel heat transfer correlations were improved using the data and present direct model-data comparisons for all tests documented in Part I. Our results show that our network flow models have been substantially improved. The CFD modeling presented here describes the complex nature of vessel heat transfer and for the first time demonstrates that flow and heat transfer in vessels can be modeled directly without the need for correlations.

  20. Seismic response analysis and test of CHASNUPP steam generator lower part model

    SciTech Connect

    Liang, H.; Jinkang, X.; Jingxian, Z.; Yinbiao, H.; Peizhu, W.

    1996-12-01

    The seismic response analysis and test of CHASNUPP steam generator lower part model has been performed. The lower part model consists of a tube sheet, 441 U-shaped rods (modeled on U-shaped tubes), 9 tie rods, a tube bundle wrapper, a lower shell and some position bolts between the lower shell and the wrapper. The analytical and experimental data show that the steam generator lower part model is stiffer than the previous pure tube bundle model. The movement of the lower part model appears in a systematic mode in earthquake condition. The fundamental natural frequency of this model is higher than that of the tube bundle model and lower than that of the lower shell. The global frequency components are absolutely dominant. The local frequency components are insignificant. The experimental data are in good agreement with FEM results. The effectiveness of the mathematical model is verified. The effects of the contained water in the lower shell and the added water of the rod are both considered. The research work is practical in reactor engineering.

  1. Bayesian two-part spatial models for semicontinuous data with application to emergency department expenditures.

    PubMed

    Neelon, Brian; Zhu, Li; Neelon, Sara E Benjamin

    2015-07-01

    In health services research, it is common to encounter semicontinuous data characterized by a point mass at zero and a continuous distribution of positive values. Examples include medical expenditures, in which the zeros represent patients who do not use health services, while the continuous distribution describes the level of expenditures among users. Semicontinuous data are customarily analyzed using two-part mixture models. In the spatial analysis of semicontinuous data, two-part models are especially appealing because they provide a joint picture of how health services utilization and associated expenditures vary across geographic regions. However, when applying these models, careful attention must be paid to distributional choices, as model misspecification can lead to biased and imprecise inferences. This paper introduces a broad class of Bayesian two-part models for the spatial analysis of semicontinuous data. Specific models considered include two-part lognormal, log skew-elliptical, and Bayesian non-parametric models. Multivariate conditionally autoregressive priors are used to link model components and provide spatial smoothing across neighboring regions, resulting in a joint spatial modeling framework for health utilization and expenditures. We develop a fully conjugate Gibbs sampling scheme, leading to efficient posterior computation. We illustrate the approach using data from a recent study of emergency department expenditures. PMID:25649743

  2. Magnetic state of K0.8Fe1.6Se2 from a five-orbital Hubbard model in the Hartree-Fock approximation

    NASA Astrophysics Data System (ADS)

    Luo, Qinlong; Nicholson, Andrew; Riera, José; Yao, Dao-Xin; Moreo, Adriana; Dagotto, Elbio

    2011-10-01

    Motivated by the recent discovery of Fe-based superconductors close to an antiferromagnetic insulator in the experimental phase diagram, here the five-orbital Hubbard model (without lattice distortions) is studied using the real-space Hartree-Fock approximation, employing a 10×10 Fe cluster with Fe vacancies in a 5×5 pattern. Varying the Hubbard and Hund couplings, and at electronic density n=6.0, the phase diagram contains an insulating state with the same spin pattern as observed experimentally, involving 2×2 ferromagnetic plaquettes coupled with one another antiferromagnetically. The presence of local ferromagnetic tendencies is in qualitative agreement with Lanczos results for the three-orbital model also reported here. The magnetic moment ˜3μB/Fe is in good agreement with experiments. Several other phases are also stabilized in the phase diagram, in agreement with recent calculations using phenomenological models.

  3. Magnetic state of K0.8Fe1.6Se2 from a five-orbital Hubbard model in the Hartree-Fock approximation

    SciTech Connect

    Luo, Qinlong; Nicholson, Andrew D; Riera, J. A.; Yao, Dao-Xin; Moreo, Adriana; Dagotto, Elbio R

    2011-01-01

    Motivated by the recent discovery of Fe-based superconductors close to an antiferromagnetic insulator in the experimental phase diagram, here the five-orbital Hubbard model (without lattice distortions) is studied using the real-space Hartree-Fock approximation, employing a 10 10 Fe cluster with Fe vacancies in a5 5 pattern. Varying the Hubbard and Hund couplings, and at electronic density n = 6.0, the phase diagram contains an insulating state with the same spin pattern as observed experimentally, involving 2 2 ferromagnetic plaquettes coupled with one another antiferromagnetically. The presence of local ferromagnetic tendencies is in qualitative agreement with Lanczos results for the three-orbital model also reported here. The magnetic moment 3 B /Fe is in good agreement with experiments. Several other phases are also stabilized in the phase diagram, in agreement with recent calculations using phenomenological models.

  4. Effect of irrigation on Fe(III)-SO42- redox cycling and arsenic mobilization in shallow groundwater from the Datong basin, China: Evidence from hydrochemical monitoring and modeling

    NASA Astrophysics Data System (ADS)

    Xie, Xianjun; Wang, Yanxin; Li, Junxia; Yu, Qian; Wu, Ya; Su, Chunli; Duan, Mengyu

    2015-04-01

    Seasonal hydrochemical monitoring has been conducted at a well-known arsenic (As) contaminated site to understand the critical controlling processes on As mobilization and enrichment in groundwater. The hydrochemical results indicate that the water chemistry at the studied site is mainly controlled by evaporates dissolution, and redox reactions during irrigation and non-irrigation periods, respectively. The measured redox-sensitive components indicate that the groundwater experienced periodic redox changes from irrigation to non-irrigation periods and that an enhanced reducing environment prevailed during the non-irrigation period. The observed high As concentration and the strong positive correlation between As and Fe support the conclusion that the Fe oxides/hydroxides reduction and Fe sulfide oxidation releases As during the irrigation period. However, the relatively low As concentration and the close inverse correlation between As, Fe and SO42- show that Fe(III) and SO42- reduction accompanied by the formation of Fe sulfide precipitates, retains As during the non-irrigation periods. The geochemical inverse modeling performed for the selected wells confirms that Fe oxide/hydroxide and Fe sulfide dissolution as well as siderite precipitation are the dominant processes related to the mobilization of As during the water evolution from the pre-irrigation to irrigation period, while Fe sulfide precipitation immobilize As during the groundwater evolution from the irrigation to the post-irrigation period. In general, the combined results of the hydrochemical monitoring and the geochemical inverse modeling support the conclusion that the Fe(III)-SO42- redox cycling induced by periodic irrigation practices controls the mobilization of As in groundwater at this site.

  5. Microstructural Evolution and Compressive Properties of Two-Phase Nb-Fe Alloys Containing the C14 Laves Phase NbFe2 Intermetallic Compound

    NASA Astrophysics Data System (ADS)

    Li, K. W.; Wang, X. B.; Wang, W. X.; Li, S. M.; Gong, D. Q.; Fu, H. Z.

    2016-02-01

    Microstructural evolution and compressive properties of two-phase Nb-Fe binary alloys based on the C14 Laves phase NbFe2 were characterized at both the hypo- and hypereutectic compositions. The experimental results indicated that the microstructures of the two alloys consisted of fully eutectics containing Fe and NbFe2 phases at the bottom of the ingots corresponding to the largest solidification rates. With the decrease of solidification rate, the microstructures developed into primary Fe (NbFe2) dendrites plus eutectics in the middle and top parts of the ingots. The microstructural evolutions along the axis of the ingots were analyzed by considering the competitive growth between the primary phase and eutectic as well as using microstructure selection models based on the maximum interface temperature criterion. Furthermore, the compressive properties of the two alloys were measured and the enhancements were explained in terms of the second Fe phase and halo toughening mechanisms.

  6. Microstructural characterization of selected AEA/UCSB model FeCuMn alloys

    SciTech Connect

    Rice, P.M.; Stoller, R.E.

    1996-06-01

    A set of 22 model ferritic alloys was purchased as part of a collaborative research program by the AEA Harwell Laboratory and the University of California at Santa Barbara. Nine of these alloys were selected by the Oak Ridge National Laboratory for use in a series of ion irradiation experiments investigating dispersed barrier hardening. These nine alloys contain varying amounts of copper, manganese, titanium, carbon, and nitrogen. The alloys have been characterized by transmission electron microscopy in the as-received condition to provide a baseline for comparison with the irradiated specimens. A description of the microstructural observations is provided for future reference. This summary focuses on the type and size distributions of the precipitates present; grain size and dislocation measurements are also included.

  7. Spin fluctuations and superconductivity in a 3D tight-binding model for BaFe2As2

    SciTech Connect

    Graser, Siegfried; Kemper, Alexander F; Maier, Thomas A; Cheng, Hai-Ping; Hirschfeld, Peter; Scalapino, Douglas

    2010-01-01

    Despite the wealth of experimental data on the Fe-pnictide compounds of the KFe2As2 type, K=Ba, Ca, or Sr, the main theoretical work based on multiorbital tight-binding models has been restricted so far to the study of the related 1111 compounds. This can be ascribed to the more three-dimensional electronic structure found by ab initio calculations for the 122 materials, making this system less amenable to model development. In addition, the more complicated Brillouin zone BZ of the body-centered tetragonal symmetry does not allow a straightforward unfolding of the electronic band structure into an effective 1Fe/unit cell BZ. Here we present an effective five-orbital tight-binding fit of the full density functional theory band structure for BaFe2As2 including the kz dispersions. We compare the five-orbital spin fluctuation model to one previously studied for LaOFeAs and calculate the random-phase approximation enhanced susceptibility. Using the fluctuation ex- change approximation to determine the leading pairing instability, we then examine the differences between a strictly two-dimensional model calculation over a single kz cut of the BZ and a completely three-dimensional approach. We find pairing states quite similar to the 1111 materials, with generic quasi-isotropic pairing on the hole sheets and nodal states on the electron sheets at kz=0, which however are gapped as the system is hole doped. On the other hand, a substantial kz dependence of the order parameter remains, with most of the pairing strength deriving from processes near kz=?. These states exhibit a tendency for an enhanced anisotropy on the hole sheets and a reduced anisotropy on the electron sheets near the top of the BZ.

  8. Polymersomes containing iron sulfide (FeS) as primordial cell model : for the investigation of energy providing redox reactions.

    PubMed

    Alpermann, Theodor; Rüdel, Kristin; Rüger, Ronny; Steiniger, Frank; Nietzsche, Sandor; Filiz, Volkan; Förster, Stephan; Fahr, Alfred; Weigand, Wolfgang

    2011-04-01

    According to Wächtershäuser's "Iron-Sulfur-World" one major requirement for the development of life on the prebiotic Earth is compartmentalization. Vesicles spontaneously formed from amphiphilic components containing a specific set of molecules including sulfide minerals may have lead to the first autotrophic prebiotic units. The iron sulfide minerals may have been formed by geological conversions in the environment of deep-sea volcanos (black smokers), which can be observed even today. Wächtershäuser postulated the evolution of chemical pathways as fundamentals of the origin of life on earth. In contrast to the classical Miller-Urey experiment, depending on external energy sources, the "Iron-Sulfur-World" is based on the catalytic and energy reproducing redox system FeS+H2S-->FeS2+H2. The energy release out of this redox reaction (∆RG°=-38 kJ/mol, pH 0) could be the cause for the subsequent synthesis of complex organic molecules and the precondition for the development of more complex units similar to cells known today. Here we show the possibility for precipitating iron sulfide inside vesicles composed of amphiphilic block-copolymers as a model system for a first prebiotic unit. Our findings could be an indication for a chemoautotrophic FeS based origin of life. PMID:20697814

  9. Polymersomes Containing Iron Sulfide (FeS) as Primordial Cell Model. For the investigation of energy providing redox reactions

    NASA Astrophysics Data System (ADS)

    Alpermann, Theodor; Rüdel, Kristin; Rüger, Ronny; Steiniger, Frank; Nietzsche, Sandor; Filiz, Volkan; Förster, Stephan; Fahr, Alfred; Weigand, Wolfgang

    2011-04-01

    According to Wächtershäuser's "Iron-Sulfur-World" one major requirement for the development of life on the prebiotic Earth is compartmentalization. Vesicles spontaneously formed from amphiphilic components containing a specific set of molecules including sulfide minerals may have lead to the first autotrophic prebiotic units. The iron sulfide minerals may have been formed by geological conversions in the environment of deep-sea volcanos (black smokers), which can be observed even today. Wächtershäuser postulated the evolution of chemical pathways as fundamentals of the origin of life on earth. In contrast to the classical Miller-Urey experiment, depending on external energy sources, the "Iron-Sulfur-World" is based on the catalytic and energy reproducing redox system FeS + {H_2}S to FeS{}_2 + {H_2} . The energy release out of this redox reaction (∆RG° = -38 kJ/mol, pH 0) could be the cause for the subsequent synthesis of complex organic molecules and the precondition for the development of more complex units similar to cells known today. Here we show the possibility for precipitating iron sulfide inside vesicles composed of amphiphilic block-copolymers as a model system for a first prebiotic unit. Our findings could be an indication for a chemoautotrophic FeS based origin of life.

  10. 12 CFR Appendix A to Part 239 - Mutual Holding Company Model Charter

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 4 2012-01-01 2012-01-01 false Mutual Holding Company Model Charter A Appendix A to Part 239 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL...—Mutual Holding Company Model Charter FEDERAL MUTUAL HOLDING COMPANY CHARTER Section 1: Corporate...

  11. 12 CFR Appendix A to Part 239 - Mutual Holding Company Model Charter

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 4 2014-01-01 2014-01-01 false Mutual Holding Company Model Charter A Appendix A to Part 239 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL...—Mutual Holding Company Model Charter FEDERAL MUTUAL HOLDING COMPANY CHARTER Section 1: Corporate...

  12. Efficacy of Different Concrete Models for Teaching the Part-Whole Construct for Fractions

    ERIC Educational Resources Information Center

    Cramer, Kathleen; Wyberg, Terry

    2009-01-01

    The effectiveness of different concrete and pictorial models on students' understanding of the part-whole construct for fractions was investigated. Using interview data from fourth and fifth grade students from three different districts that adopted the "Mathematics Trailblazers" series, authors identified strengths and limitations of models used.…

  13. 12 CFR Appendix H to Part 226 - Closed-End Model Forms and Clauses

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... RESERVE SYSTEM (CONTINUED) TRUTH IN LENDING (REGULATION Z) Pt. 226, App. H Appendix H to Part 226— Closed... Summary Model Clause (§ 226.18(s)) H-4(F)—Adjustable-Rate Mortgage or Step-Rate Mortgage Interest Rate and Payment Summary Model Clause (§ 226.18(s)) H-4(G)—Mortgage with Negative Amortization Interest Rate...

  14. 42 CFR Appendix to Part 54a - Model Notice of Individuals Receiving Substance Abuse Services

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., ET SEQ., FOR SUBSTANCE ABUSE PREVENTION AND TREATMENT SERVICES Pt. 54a, App. Appendix to Part 54a—Model Notice of Individuals Receiving Substance Abuse Services Model Notice to Individuals Receiving Substance Abuse Services No provider of substance abuse services receiving Federal funds from the...

  15. 42 CFR Appendix to Part 54a - Model Notice of Individuals Receiving Substance Abuse Services

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., et seq., FOR SUBSTANCE ABUSE PREVENTION AND TREATMENT SERVICES Pt. 54a, App. Appendix to Part 54a—Model Notice of Individuals Receiving Substance Abuse Services Model Notice to Individuals Receiving Substance Abuse Services No provider of substance abuse services receiving Federal funds from the...

  16. 42 CFR Appendix to Part 54a - Model Notice of Individuals Receiving Substance Abuse Services

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., ET SEQ., FOR SUBSTANCE ABUSE PREVENTION AND TREATMENT SERVICES Pt. 54a, App. Appendix to Part 54a—Model Notice of Individuals Receiving Substance Abuse Services Model Notice to Individuals Receiving Substance Abuse Services No provider of substance abuse services receiving Federal funds from the...

  17. 42 CFR Appendix to Part 54a - Model Notice of Individuals Receiving Substance Abuse Services

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., et seq., FOR SUBSTANCE ABUSE PREVENTION AND TREATMENT SERVICES Pt. 54a, App. Appendix to Part 54a—Model Notice of Individuals Receiving Substance Abuse Services Model Notice to Individuals Receiving Substance Abuse Services No provider of substance abuse services receiving Federal funds from the...

  18. Observed and modeled seasonal trends in dissolved and particulate Cu, Fe, Mn, and Zn in a mining-impacted stream.

    PubMed

    Butler, Barbara A; Ranville, James F; Ross, Philippe E

    2008-06-01

    North Fork Clear Creek (NFCC) in Colorado, an acid-mine drainage (AMD) impacted stream, was chosen to examine the distribution of dissolved and particulate Cu, Fe, Mn, and Zn in the water column, with respect to seasonal hydrologic controls. NFCC is a high-gradient stream with discharge directly related to snowmelt and strong seasonal storms. Additionally, conditions in the stream cause rapid precipitation of large amounts of hydrous iron oxides (HFO) that sequester metals. Because AMD-impacted systems are complex, geochemical modeling may assist with predictions and/or confirmations of processes occurring in these environments. This research used Visual-MINTEQ to determine if field data collected over a two and one-half year study would be well represented by modeling with a currently existing model, while limiting the number of processes modeled and without modifications to the existing model's parameters. Observed distributions between dissolved and particulate phases in the water column varied greatly among the metals, with average dissolved fractions being >90% for Mn, approximately 75% for Zn, approximately 30% for Cu, and <10% for Fe. A strong seasonal trend was observed for the metals predominantly in the dissolved phase (Mn and Zn), with increasing concentrations during base-flow conditions and decreasing concentrations during spring-runoff. This trend was less obvious for Cu and Fe. Within hydrologic seasons, storm events significantly influenced in-stream metals concentrations. The most simplified modeling, using solely sorption to HFO, gave predicted percentage particulate Cu results for most samples to within a factor of two of the measured values, but modeling data were biased toward over-prediction. About one-half of the percentage particulate Zn data comparisons fell within a factor of two, with the remaining data being under-predicted. Slightly more complex modeling, which included dissolved organic carbon (DOC) as a solution phase ligand

  19. Chemical modeling of backfill composed of quartz sand, lime and an Fe-phase

    SciTech Connect

    Meike, A.; Glassley, W.E.

    1997-01-01

    The area adjacent to the waste package is an important component of the engineered barrier system in a high level radioactive waste repository. The combination of lime, quartz sand, and a phase containing reduced iron is investigated whether it can achieve reduction of oxygen in the waste emplacement drift (thereby reducin corrosion rates) and increase the pH. The simulations conducted to date have examined the following backfill options: Fe metal only, Fe metal and lime, and iron metal/lime/quartz sand in equal volume ratios. Each option was simulated under two environments: limited and unlimited air exchange with the atmosphere. Results suggest that the most important variable during the process of chemical conditioning is the amount of air exchange that occurs in the emplacement drift. The desired chemical conditioing (both oxidation potential and pH) will be far less effective in an emplacement that experiences an unlimited exchange of air with the atmosphere.

  20. Atomistic modeling of the interaction of cladding elements (Fe, Ni, Cr) with U-Zr fuel

    NASA Astrophysics Data System (ADS)

    Bozzolo, G.; Mosca, H. O.; Yacout, A. M.; Hofman, G. L.

    2011-07-01

    Atomistic simulations of U-Zr fuel and its interaction with Fe, Ni, and Cr using the BFS method for alloys are presented. Results for the γU-βZr solid solution are discussed, including the behavior of the lattice parameter and coefficient of thermal expansion as a function of concentration and temperature. Output from these calculations is used to study the surface structure of γU-βZr for different crystallographic orientations, determining the concentration profiles, surface energy, and segregation behavior. The analysis is completed with simulations of the deposition of Fe, Ni and Cr on U-Zr substrates with varying Zr concentration. All results are discussed and interpreted by means of the concepts of strain and chemical energy underlying the BFS method, thus obtaining a simple explanation for the observed Zr segregation and its influence in allowing for cladding elements diffusion into the U-Zr fuel.

  1. Radiation tolerance of neutron-irradiated model Fe-Cr-Al alloys

    NASA Astrophysics Data System (ADS)

    Field, Kevin G.; Hu, Xunxiang; Littrell, Kenneth C.; Yamamoto, Yukinori; Snead, Lance L.

    2015-10-01

    The Fe-Cr-Al alloy system has the potential to form an important class of enhanced accident-tolerant cladding materials in the nuclear power industry owing to the alloy system's higher oxidation resistance in high-temperature steam environments compared with traditional zirconium-based alloys. However, radiation tolerance of Fe-Cr-Al alloys has not been fully established. In this study, a series of Fe-Cr-Al alloys with 10-18 wt % Cr and 2.9-4.9 wt % Al were neutron irradiated at 382 °C to 1.8 dpa to investigate the irradiation-induced microstructural and mechanical property evolution as a function of alloy composition. Dislocation loops with Burgers vector of a/2<111> and a<100> were detected and quantified. Results indicate precipitation of Cr-rich α‧ is primarily dependent on the bulk chromium composition. Mechanical testing of sub-size-irradiated tensile specimens indicates the hardening response seen after irradiation is dependent on the bulk chromium composition. A structure-property relationship was developed; it indicated that the change in yield strength after irradiation is caused by the formation of these radiation-induced defects and is dominated by the large number density of Cr-rich α‧ precipitates at sufficiently high chromium contents after irradiation.

  2. Radiation tolerance of neutron-irradiated model Fe-Cr-Al alloys

    DOE PAGESBeta

    Field, Kevin G.; Hu, Xunxiang; Littrell, Kenneth C.; Yamamoto, Yukinori; Snead, Lance Lewis

    2015-07-14

    The Fe Cr Al alloy system has the potential to form an important class of enhanced accident-tolerant cladding materials in the nuclear power industry owing to the alloy system's higher oxidation resistance in high-temperature steam environments compared with traditional zirconium-based alloys. However, radiation tolerance of Fe Cr Al alloys has not been fully established. In this study, a series of Fe Cr Al alloys with 10 18 wt % Cr and 2.9 4.9 wt % Al were neutron irradiated at 382 C to 1.8 dpa to investigate the irradiation-induced microstructural and mechanical property evolution as a function of alloy composition.more » Dislocation loops with Burgers vector of a/2 111 and a 100 were detected and quantified. Results indicate precipitation of Cr-rich is primarily dependent on the bulk chromium composition. Mechanical testing of sub-size-irradiated tensile specimens indicates the hardening response seen after irradiation is dependent on the bulk chromium composition. Furthermore, a structure property relationship was developed; it indicated that the change in yield strength after irradiation is caused by the formation of these radiation-induced defects and is dominated by the large number density of Cr-rich α' precipitates at sufficiently high chromium contents after irradiation.« less

  3. Radiation tolerance of neutron-irradiated model Fe-Cr-Al alloys

    NASA Astrophysics Data System (ADS)

    Field, Kevin G.; Hu, Xunxiang; Littrell, Kenneth C.; Yamamoto, Yukinori; Snead, Lance L.

    2015-10-01

    The Fe-Cr-Al alloy system has the potential to form an important class of enhanced accident-tolerant cladding materials in the nuclear power industry owing to the alloy system's higher oxidation resistance in high-temperature steam environments compared with traditional zirconium-based alloys. However, radiation tolerance of Fe-Cr-Al alloys has not been fully established. In this study, a series of Fe-Cr-Al alloys with 10-18 wt % Cr and 2.9-4.9 wt % Al were neutron irradiated at 382 °C to 1.8 dpa to investigate the irradiation-induced microstructural and mechanical property evolution as a function of alloy composition. Dislocation loops with Burgers vector of a/2<111> and a<100> were detected and quantified. Results indicate precipitation of Cr-rich α‧ is primarily dependent on the bulk chromium composition. Mechanical testing of sub-size-irradiated tensile specimens indicates the hardening response seen after irradiation is dependent on the bulk chromium composition. A structure-property relationship was developed; it indicated that the change in yield strength after irradiation is caused by the formation of these radiation-induced defects and is dominated by the large number density of Cr-rich α‧ precipitates at sufficiently high chromium contents after irradiation.

  4. Radiation tolerance of neutron-irradiated model Fe-Cr-Al alloys

    SciTech Connect

    Field, Kevin G.; Hu, Xunxiang; Littrell, Kenneth C.; Yamamoto, Yukinori; Snead, Lance Lewis

    2015-07-14

    The Fe Cr Al alloy system has the potential to form an important class of enhanced accident-tolerant cladding materials in the nuclear power industry owing to the alloy system's higher oxidation resistance in high-temperature steam environments compared with traditional zirconium-based alloys. However, radiation tolerance of Fe Cr Al alloys has not been fully established. In this study, a series of Fe Cr Al alloys with 10 18 wt % Cr and 2.9 4.9 wt % Al were neutron irradiated at 382 C to 1.8 dpa to investigate the irradiation-induced microstructural and mechanical property evolution as a function of alloy composition. Dislocation loops with Burgers vector of a/2 111 and a 100 were detected and quantified. Results indicate precipitation of Cr-rich is primarily dependent on the bulk chromium composition. Mechanical testing of sub-size-irradiated tensile specimens indicates the hardening response seen after irradiation is dependent on the bulk chromium composition. Furthermore, a structure property relationship was developed; it indicated that the change in yield strength after irradiation is caused by the formation of these radiation-induced defects and is dominated by the large number density of Cr-rich α' precipitates at sufficiently high chromium contents after irradiation.

  5. AERMOD: A DISPERSION MODEL FOR INDUSTRIAL SOURCE APPLICATIONS PART I: GENERAL MODEL FORMULATION AND BOUNDARY LAYER CHARACTERIZATION

    EPA Science Inventory

    The formulations of the AMS/EPA Regulatory Model Improvement Committee's applied air dispersion model (AERMOD) as related to the characterization of the planetary boundary layer are described. This is the first in a series of three articles. Part II describes the formulation of...

  6. The iron-site structure of [Fe]-hydrogenase and model systems: an X-ray absorption near edge spectroscopy study†‡

    PubMed Central

    Salomone-Stagni, Marco; Stellato, Francesco; Whaley, C. Matthew; Vogt, Sonja; Morante, Silvia; Shima, Seigo; Rauchfuss, Thomas B.; Meyer-Klaucke, Wolfram

    2012-01-01

    The [Fe]-hydrogenase is an ideal system for studying the electronic properties of the low spin iron site that is common to the catalytic centres of all hydrogenases. Because they have no auxiliary iron-sulfur clusters and possess a cofactor containing a single iron centre, the [Fe]-hydrogenases are well suited for spectroscopic analysis of those factors required for the activation of molecular hydrogen. Specifically, in this study we shed light on the electronic and molecular structure of the iron centre by XAS analysis of [Fe]-hydrogenase from Methanocaldococcus jannashii and five model complexes (Fe(ethanedithiolate)-(CO)2(PMe3)2, [K(18-crown-6)]2[Fe(CN)2(CO)3], K[Fe(CN)(CO)4], K3[Fe(iii)(CN)6], K4[Fe(ii)(CN)6]). The different electron donors have a strong influence on the iron absorption K-edge energy position, which is frequently used to determine the metal oxidation state. Our results demonstrate that the K-edges of Fe(ii) complexes, achieved with low-spin ferrous thiolates, are consistent with a ferrous centre in the [Fe]-hydrogenase from Methanocaldococcus jannashii. The metal geometry also strongly influences the XANES and thus the electronic structure. Using in silico simulation, we were able to reproduce the main features of the XANES spectra and describe the effects of individual donor contributions on the spectra. Thereby, we reveal the essential role of an unusual carbon donor coming from an acyl group of the cofactor in the determination of the electronic structure required for the activity of the enzyme. PMID:20221540

  7. Magnetic correlations beyond the Heisenberg model in an Fe monolayer on Rh(0 0 1)

    NASA Astrophysics Data System (ADS)

    Deák, A.; Palotás, K.; Szunyogh, L.; Szabó, I. A.

    2015-04-01

    Motivated by a recent experimental observation of a complex magnetic structure (Takada et al 2013 J. Magn. Magn. Mater. 329 95) we present a theoretical study of the magnetic structure of an Fe monolayer deposited on Rh(0 0 1). We use a classical spin Hamiltonian with parameters obtained from ab initio calculations and go beyond the usual anisotropic Heisenberg model by including isotropic biquadratic interactions. Zero-temperature Landau-Lifshitz-Gilbert spin dynamics simulations lead to a complex collinear spin configuration that, however, contradicts experimental findings. We thus conclude that higher order multi-spin interactions are likely needed to account for the magnetic ordering of the system.

  8. Model assessment of protective barriers: Part 4, Status of FY 1992 work

    SciTech Connect

    Fayer, M.J.

    1993-03-01

    Protective barriers are being considered for use at the Hanford Site to enhance the isolation of radioactive wastes from water, plant, and animal intrusion. This study is part of an ongoing effort to assess the effectiveness of protective barriers for isolation of wastes from water. Part I of this study was the original modeling assessment by Pacific Northwest Laboratory of various protective barrier designs (e.g., soil type, vegetation). In Part 11 of this study, additional barrier designs were reviewed and several barrier modeling assumptions were tested. A test plan was then produced that detailed the requirement for hydrologic modeling of protective barriers. Part III of this study summarized the status of work in FY 1990 dealing with two-dimensional flow beneath the barrier and with validation testing using lysimeter data. This report (Part IV) addresses the application of a calibrated model to a much longer data set, the application of the calibrated model to a lysimeter that received a different treatment, and the effect of hysteresis on the behavior of water in the protective barrier.

  9. Model Simulation of Ionosphere Electron Density with Dynamic Transportation and Mechanism of Sporadic E Layers in Lower Part of Ionosphere

    NASA Astrophysics Data System (ADS)

    Lin, Y. C.; Chu, Y. H.

    2015-12-01

    There are many physical theories responsible for explanation the generation mechanism of sporadic E (Es) plasma irregularities. In middle latitude, it's generally believed that sporadic E layers occur in vertical ion convergent areas driven by horizontal neutral wind shear. The sporadic E layers appear characteristic of abundant metallic ion species (i.e., Fe+, Mg+, Na+), that lifetime are longer than molecular ions by a factor of several orders, have been demonstrated by rocket-borne mass spectrometric measurements. On the basic of the GPS Radio Occultation (RO), using the scintillations of the GPS signal-to-noise ratio and intense fluctuation of excess phase, the global and seasonal sporadic E layers occurrence rates could be retrieved. In our previous study we found there is averaged 10 kilometers shift in height between the COSMIC-retrieved sporadic E layer occurrence rate and the sporadic E occurrence rate modeled from considering the convergence/divergence of Fe+ vertical flux. There are many reasons that maybe result in the altitude differences, e.g., tidal wind with phase shift, electric field driven force, iron species distributions. In this research, the quantitative analyses for electric field drives Es layers translations in vertical direction are presented. The tidal wind driven sporadic E layers have been simulating by modeling several nonmetallic ions (O+(4S), O+(2D), O+(2p), N+, N2+, O2+, NO+) and metallic ions (Fe+, FeO2+, FeN2+, FeO+) with wind shear transportation. The simulation result shows the Fe+ particles accumulate at zonal wind shear convergent regions and form the thin sporadic E layers. With the electric field taking into account, the whole shape of sporadic E layers vertical shift 2~5 km that depending on what magnitude and direction of electric field is added.

  10. Synthesis of Au-Fe3O4 heterostructured nanoparticles for in vivo computed tomography and magnetic resonance dual model imaging

    NASA Astrophysics Data System (ADS)

    Zhu, Jing; Lu, Yinjie; Li, Yonggang; Jiang, Jiang; Cheng, Liang; Liu, Zhuang; Guo, Liang; Pan, Yue; Gu, Hongwei

    2013-12-01

    Water-soluble Au-Fe3O4 heterostructured nanoparticles with high biocompatibility were synthesized and applied as a dual modality contrast agent. These nanoparticles present strong CT/MRI contrast enhancement in a rabbit model. Low concentrations of Au-Fe3O4 were found to obtain a similar effect to high concentrations of a commercial iodine agent in the CT image.Water-soluble Au-Fe3O4 heterostructured nanoparticles with high biocompatibility were synthesized and applied as a dual modality contrast agent. These nanoparticles present strong CT/MRI contrast enhancement in a rabbit model. Low concentrations of Au-Fe3O4 were found to obtain a similar effect to high concentrations of a commercial iodine agent in the CT image. Electronic supplementary information (ESI) available: Details of general experimental procedures, XRD patterns, UV-vis absorption spectra, phase contrast imaging, and CT imaging. See DOI: 10.1039/c3nr04730j

  11. A thermodynamic model for di-trioctahedral chlorite from experimental and natural data in the system MgO-FeO-Al2O3-SiO2-H2O: applications to P- T sections and geothermometry

    NASA Astrophysics Data System (ADS)

    Lanari, Pierre; Wagner, Thomas; Vidal, Olivier

    2014-02-01

    We present a new thermodynamic activity-composition model for di-trioctahedral chlorite in the system FeO-MgO-Al2O3-SiO2-H2O that is based on the Holland-Powell internally consistent thermodynamic data set. The model is formulated in terms of four linearly independent end-members, which are amesite, clinochlore, daphnite and sudoite. These account for the most important crystal-chemical substitutions in chlorite, the Fe-Mg, Tschermak and di-trioctahedral substitution. The ideal part of end-member activities is modeled with a mixing-on-site formalism, and non-ideality is described by a macroscopic symmetric (regular) formalism. The symmetric interaction parameters were calibrated using a set of 271 published chlorite analyses for which robust independent temperature estimates are available. In addition, adjustment of the standard state thermodynamic properties of sudoite was required to accurately reproduce experimental brackets involving sudoite. This new model was tested by calculating representative P- T sections for metasediments at low temperatures (<400 °C), in particular sudoite and chlorite bearing metapelites from Crete. Comparison between the calculated mineral assemblages and field data shows that the new model is able to predict the coexistence of chlorite and sudoite at low metamorphic temperatures. The predicted lower limit of the chloritoid stability field is also in better agreement with petrological observations. For practical applications to metamorphic and hydrothermal environments, two new semi-empirical chlorite geothermometers named Chl(1) and Chl(2) were calibrated based on the chlorite + quartz + water equilibrium (2 clinochlore + 3 sudoite = 4 amesite + 4 H2O + 7 quartz). The Chl(1) thermometer requires knowledge of the (Fe3+/ΣFe) ratio in chlorite and predicts correct temperatures for a range of redox conditions. The Chl(2) geothermometer which assumes that all iron in chlorite is ferrous has been applied to partially recrystallized

  12. Rhodospirillium rubrum CO-dehydrogenase. Part 1. Spectroscopic studies of CODH variant C531A indicate the presence of a binuclear [FeNi] cluster

    SciTech Connect

    Staples, C.R.; Heo, J.; Spangler, N.J.; Kerby, R.L.; Roberts, G.P.; Ludden, P.W.

    1999-12-08

    A variant of the carbon monoxide dehydrogenase (CODH) from Rhodospirillum rubrum was constructed by site-directed mutagenesis of the cooS gene to yield a CODH with ala in place of cys-531. This variant form of CODH (C531A) has a metal content identical to that of wild-type CODH but has an extremely slow turnover rate. Cys-531 is not essential for construction of the [Fe{sub 4}S{sub 4}] clusters or for incorporation of nickel. The K{sub m} for methyl viologen is identical to that of wild-type CODH, but the K{sub m} for CO is approximately 30% that of wild-type CODH. The data suggest that in C531A CODH a rate-limiting step has been introduced at the point of electron transfer from the Ni site to an associated [Fe{sub 4}S{sub 4}]{sub C} cluster. Examination of indigo carmine-poised, CO-pretreated C531A CODH revealed the presence of a paramagnetic species (g = 2.33, 2.10, 2.03; g{sub ave} = 2.16), which was also observed in dithionite-treated samples. This species was shown to represent as much as 0.90 {+-} 0.10 spins/molecule, yet production of the species from fully oxidized C531A CODH did not involve a concurrent decrease in the molar extinction coefficient at 420 nm, indicating that the [Fe{sub 4}S{sub 4}] clusters remained in the 2+ oxidation state. {sup 61}Ni-substituted CO-pretreated C531A CODH, when poised with indigo carmine, showed no broadening of the resonances, indicating that no detectable spin density resides upon Ni. Comparisons of the EPR spectrum of the g{sub ave} = 2.16 species to Ni-C(CO) and Ni-C of Alcaligenes eutrophus [NiFe] hydrogenase are presented. On the basis of these comparisons and on the lack of {sup 61}Ni broadening, the g{sub ave} = 2.16 resonance is interpreted as arising from a [(CO{sub L})Fe{sup 3+}-Ni{sup 2+}-H{sup {minus}}]{sup 4+} (S = 1/2) system, where CO{sub L} is an activating nonsubstrate CO ligand. On the basis of the absence of spectroscopic features present in wild-type CODH, and representing coupled forms of the putative

  13. Detecting Controller Malfunctions in Electromagnetic Environments. Part 1; Modeling and Estimation of Nominal System Function

    NASA Technical Reports Server (NTRS)

    Weinstein, Bernice

    1999-01-01

    A strategy for detecting control law calculation errors in critical flight control computers during laboratory validation testing is presented. This paper addresses Part I of the detection strategy which involves the use of modeling of the aircraft control laws and the design of Kalman filters to predict the correct control commands. Part II of the strategy which involves the use of the predicted control commands to detect control command errors is presented in the companion paper.

  14. Reaction mechanism of WGS and PROX reactions catalyzed by Pt/oxide catalysts revealed by an FeO(111)/Pt(111) inverse model catalyst.

    PubMed

    Xu, Lingshun; Wu, Zongfang; Jin, Yuekang; Ma, Yunsheng; Huang, Weixin

    2013-08-01

    We have employed XPS and TDS to study the adsorption and surface reactions of H2O, CO and HCOOH on an FeO(111)/Pt(111) inverse model catalyst. The FeO(111)-Pt(111) interface of the FeO(111)/Pt(111) inverse model catalyst exposes coordination-unsaturated Fe(II) cations (Fe(II)CUS) and the Fe(II)CUS cations are capable of modifying the reactivity of neighbouring Pt sites. Water facilely dissociates on the Fe(II)CUS cations at the FeO(111)-Pt(111) interface to form hydroxyls that react to form both water and H2 upon heating. Hydroxyls on the Fe(II)CUS cations can react with CO(a) on the neighbouring Pt(111) sites to produce CO2 at low temperatures. Hydroxyls act as the co-catalyst in the CO oxidation by hydroxyls to CO2 (PROX reaction), while they act as one of the reactants in the CO oxidation by hydroxyls to CO2 and H2 (WGS reaction), and the recombinative reaction of hydroxyls to produce H2 is the rate-limiting step in the WGS reaction. A comparison of reaction behaviors between the interfacial CO(a) + OH reaction and the formate decomposition reaction suggest that formate is the likely surface intermediate of the CO(a) + OH reaction. These results provide some solid experimental evidence for the associative reaction mechanism of WGS and PROX reactions catalyzed by Pt/oxide catalysts. PMID:23576093

  15. Effectiveness of a regional model calibrated to different parts of a flow regime in regionalisation

    NASA Astrophysics Data System (ADS)

    Kim, H. S.

    2015-07-01

    The objective of this study was to reduce the parameter uncertainty which has an effect on the identification of the relationship between the catchment characteristics and the catchment response dynamics in ungauged catchments. A water balance model calibrated to represent the rainfall runoff characteristics over long time scales had a potential limitation in the modelling capacity to accurately predict the hydrological effects of non-stationary catchment response dynamics under different climate conditions (distinct wet and dry periods). The accuracy and precision of hydrological modelling predictions was assessed to yield a better understanding for the potential improvement of the model's predictability. In the assessment of model structure suitability to represent the non-stationary catchment response characteristics, there was a flow-dependent bias in the runoff simulations. In particular, over-prediction of the streamflow was dominant for the dry period. The poor model performance during the dry period was associated with the largely different impulse response estimates for the entire period and the dry period. The refined calibration approach was established based on assessment of model deficiencies. The rainfall-runoff models were separately calibrated to different parts of the flow regime, and the calibrated models for the separated time series were used to establish the regional models of relevant parts of the flow regime (i.e. wet and dry periods). The effectiveness of the parameter values for the refined approach in regionalisation was evaluated through investigating the accuracy of predictions of the regional models. The predictability was demonstrated using only the dry period to highlight the improvement in model performance easily veiled by the performance of the model for the whole period. The regional models from the refined calibration approach clearly enhanced the hydrological behaviour by improving the identification of the relationships between

  16. Experimental and molecular modeling studies of the interaction of the polypyridyl Fe(II) and Fe(III) complexes with DNA and BSA

    NASA Astrophysics Data System (ADS)

    Behnamfar, Mohammad Taghi; Hadadzadeh, Hassan; Simpson, Jim; Darabi, Farivash; Shahpiri, Azar; Khayamian, Taghi; Ebrahimi, Malihe; Amiri Rudbari, Hadi; Salimi, Mona

    2015-01-01

    Two mononuclear iron complexes, [Fe(tppz)2](PF6)2·H2O (1) and Fe(tppz)Cl3·2CHCl3 (2) where tppz is (2,3,5,6-tetra(2-pyridyl)pyrazine), have been synthesized and characterized by elemental analysis, spectroscopic methods (UV-Vis and IR) and single crystal X-ray structure analysis. The interaction of (1) as the nitrate salt ([Fe(tppz)2](NO3)2) with calf-thymus DNA (CT-DNA) has been monitored by UV-Vis spectroscopy, competitive fluorescence titration, circular dichroism (CD), voltammetric techniques, viscosity measurement, and gel electrophoresis. Gel electrophoresis of DNA with [Fe(tppz)2](NO3)2 demonstrated that the complex also has the ability to cleave supercoiled plasmid DNA. The results have indicated that the complex binds to CT-DNA by three binding modes, viz., electrostatic, groove and partial insertion of the pyridyl rings between the base stacks of double-stranded DNA. Molecular docking of [Fe(tppz)2](NO3)2 with the DNA sequence d(ACCGACGTCGGT)2 suggests the complex fits into the major groove. The water-insoluble complex (2) can catalyze the cleavage of BSA at 40 °C. There are no reports of the catalytic effect of polypyridyl metal complexes on the BSA cleavage. Molecular docking of (2) with BSA suggests that, when the chloro ligands in the axial positions are replaced by water molecules, the BSA can interact with the Fe(III) complex more easily.

  17. A generic discriminative part-based model for geospatial object detection in optical remote sensing images

    NASA Astrophysics Data System (ADS)

    Zhang, Wanceng; Sun, Xian; Wang, Hongqi; Fu, Kun

    2015-01-01

    Detecting geospatial objects with complex structure has been explored for years and it is still a challenging task in high resolution optical remote sensing images (RSI) interpretation. In this paper, we mainly focus on the problem of rotation variance in detecting geospatial objects and propose a generic discriminative part-based model (GDPBM) to build a practical object detection framework. In our model, a geospatial object with arbitrary orientation is divided into several parts and represented via three terms: the appearance features, the spatial deformation features and the rotation deformation features. The appearance features characterize the local patch appearance of the object and parts, and we propose a new kind of rotation invariant feature to represent the appearance using the local intensity gradients. The spatial deformation features capture the geometric deformation of parts by representing the relative displacements among parts. The rotation deformation features define the pose variances of the parts relative to the objects based on their dominant orientations. In generating the two deformation features, we introduce the statistic methods to encode the features in the category level. Concatenating the three terms of the features, a classifier based on the support vector machine is learned to detect geospatial objects. In the experiments, two datasets in optical RSI are used to evaluate the performance of our model and the results demonstrate its robustness and effectiveness.

  18. EMGD-FE: an open source graphical user interface for estimating isometric muscle forces in the lower limb using an EMG-driven model

    PubMed Central

    2014-01-01

    Background This paper describes the “EMG Driven Force Estimator (EMGD-FE)”, a Matlab® graphical user interface (GUI) application that estimates skeletal muscle forces from electromyography (EMG) signals. Muscle forces are obtained by numerically integrating a system of ordinary differential equations (ODEs) that simulates Hill-type muscle dynamics and that utilises EMG signals as input. In the current version, the GUI can estimate the forces of lower limb muscles executing isometric contractions. Muscles from other parts of the body can be tested as well, although no default values for model parameters are provided. To achieve accurate evaluations, EMG collection is performed simultaneously with torque measurement from a dynamometer. The computer application guides the user, step-by-step, to pre-process the raw EMG signals, create inputs for the muscle model, numerically integrate the ODEs and analyse the results. Results An example of the application’s functions is presented using the quadriceps femoris muscle. Individual muscle force estimations for the four components as well the knee isometric torque are shown. Conclusions The proposed GUI can estimate individual muscle forces from EMG signals of skeletal muscles. The estimation accuracy depends on several factors, including signal collection and modelling hypothesis issues. PMID:24708668

  19. Preparation of nanoparticulate Fe 2O 3—polymaleic monoester alternating Langmuir—Blodgett films with functional organic hydrophobic part

    NASA Astrophysics Data System (ADS)

    Peng, Xiao-Gang; Gao, Man-Lai; Zhao, Ying-Ying; Kang, Shi-Hai; Zhang, Yun-Hang; Zhang, Yan; Wang, De-Jun; Xiao, Liang-Zhi; Li, Tie-Jin; Chen, Hai-Yan

    1993-07-01

    An organic functional group was introduced into the inorganic nanoparticle—organic alternating LB films by the use of the polymaleic monoester with a functional lateral chain ? to replace a fatty acid. Using the polymer (PMANN), the distance between adjacent nanoparticles in the LB films is apparently decreased and the distribution of the nanoparticles in the monolayer is more homegeneous than that in the nanoparticulate Fe 2O 3—stearate monolayer. All these phenomena are ascribed to the carboxylate groups of a polymer molecule bound to two or more nanoparticles. The photovoltage response of n-type (p-type) silicon coated with a monolayer of nanoparticulate Fe 2O 3—PMANN LB films increases (decreases) for two orders.

  20. Nanostructure evolution under irradiation in FeMnNi alloys: A "grey alloy" object kinetic Monte Carlo model

    NASA Astrophysics Data System (ADS)

    Chiapetto, M.; Malerba, L.; Becquart, C. S.

    2015-07-01

    This work extends the object kinetic Monte Carlo model for neutron irradiation-induced nanostructure evolution in Fe-C binary alloys developed in [1], introducing the effects of substitutional solutes like Mn and Ni. The objective is to develop a model able to describe the nanostructural evolution of both vacancy and self-interstitial atom (SIA) defect cluster populations in Fe(C)MnNi neutron-irradiated model alloys at the operational temperature of light water reactors (∼300 °C), by simulating specific reference irradiation experiments. To do this, the effects of the substitutional solutes of interest are introduced, under simplifying assumptions, using a "grey alloy" scheme. Mn and Ni solute atoms are not explicitly introduced in the model, which therefore cannot describe their redistribution under irradiation, but their effect is introduced by modifying the parameters that govern the mobility of both SIA and vacancy clusters. In particular, the reduction of the mobility of point-defect clusters as a consequence of the presence of solutes proved to be key to explain the experimentally observed disappearance of detectable defect clusters with increasing solute content. Solute concentration is explicitly taken into account in the model as a variable determining the slowing down of self-interstitial clusters; small vacancy clusters, on the other hand, are assumed to be significantly slowed down by the presence of solutes, while for clusters bigger than 10 vacancies their complete immobility is postulated. The model, which is fully based on physical considerations and only uses a few parameters for calibration, is found to be capable of reproducing the experimental trends in terms of density and size distribution of the irradiation-induced defect populations with dose, as compared to the reference experiment, thereby providing insight into the physical mechanisms that influence the nanostructural evolution undergone by this material during irradiation.

  1. Simulation of upper-ocean biogeochemistry with a flexible-composition phytoplankton model: C, N and Si cycling and Fe limitation in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Mongin, Mathieu; Nelson, David M.; Pondaven, Philippe; Tréguer, Paul

    2006-03-01

    We previously reported the application of an upper-ocean biogeochemical model in which the elemental composition of the phytoplankton is flexible and responds to changes in light and nutrient availability [Mongin, M., Nelson, D., Pondaven, P., Brzezinski, M., Tréguer, P., 2003. Simulation of upper-ocean biogeochemistry with a flexible-composition phytoplankton model: C, N and Si cycling in the western Sargasso Sea. Deep-Sea Research I 50, 1445-1480]. That model, applied in the western Sargasso Sea, considered the cycles of C, N and Si in the upper 400 m and limitation of phytoplankton growth by N, Si and light. We now report a new version of this model that includes Fe cycling and Fe limitation and its application in the Southern Ocean. The model includes two phytoplankton groups, diatoms and non-siliceous forms. Uptake of NO 3- by phytoplankton is light dependent, but NH 4+, Si(OH) 4 and Fe uptake are not and can therefore continue through the night. The model tracks the resulting C/N and Fe/C ratios of both groups and Si/N ratio of diatoms, and permits uptake of C, N, Fe and Si to proceed independently when those ratios are close to those of nutrient-replete phytoplankton. When they indicate a deficiency cellular C, N, Fe or Si, uptake of the non-limiting elements is controlled by the content of the limiting element in accordance with the cell-quota formulation of [Droop, M., 1974. The nutrient status of algal cell in continuous culture. Journal of the Marine Biological Association of the United Kingdom 54, 825-855]. The model thus identifies the growth-limiting element and quantifies the degree of limitation from the elemental composition of the phytoplankton. We applied this model at the French KERFIX site in the Indian Ocean sector of the Southern Ocean, using meteorological forcing for that site from 1991 to 1995. As in the Sargasso Sea application, the flexible-composition structure provides simulations that are consistent with field data with only minimal

  2. A Correlation-Based Transition Model using Local Variables. Part 1; Model Formation

    NASA Technical Reports Server (NTRS)

    Menter, F. R.; Langtry, R. B.; Likki, S. R.; Suzen, Y. B.; Huang, P. G.; Volker, S.

    2006-01-01

    A new correlation-based transition model has been developed, which is based strictly on local variables. As a result, the transition model is compatible with modern computational fluid dynamics (CFD) approaches, such as unstructured grids and massive parallel execution. The model is based on two transport equations, one for intermittency and one for the transition onset criteria in terms of momentum thickness Reynolds number. The proposed transport equations do not attempt to model the physics of the transition process (unlike, e.g., turbulence models) but from a framework for the implementation of correlation-based models into general-purpose CFD methods.

  3. Transportation Sector Model of the National Energy Modeling System. Volume 2 -- Appendices: Part 1

    SciTech Connect

    1998-01-01

    This volume contains input data and parameters used in the model of the transportation sector of the National Energy Modeling System. The list of Transportation Sector Model variables includes parameters for the following: Light duty vehicle modules (fuel economy, regional sales, alternative fuel vehicles); Light duty vehicle stock modules; Light duty vehicle fleet module; Air travel module (demand model and fleet efficiency model); Freight transport module; Miscellaneous energy demand module; and Transportation emissions module. Also included in these appendices are: Light duty vehicle market classes; Maximum light duty vehicle market penetration parameters; Aircraft fleet efficiency model adjustment factors; and List of expected aircraft technology improvements.

  4. Sequential Monte Carlo filter for state estimation of LiFePO4 batteries based on an online updated model

    NASA Astrophysics Data System (ADS)

    Li, Jiahao; Klee Barillas, Joaquin; Guenther, Clemens; Danzer, Michael A.

    2014-02-01

    Battery state monitoring is one of the key techniques in battery management systems e.g. in electric vehicles. An accurate estimation can help to improve the system performance and to prolong the battery remaining useful life. Main challenges for the state estimation for LiFePO4 batteries are the flat characteristic of open-circuit-voltage over battery state of charge (SOC) and the existence of hysteresis phenomena. Classical estimation approaches like Kalman filtering show limitations to handle nonlinear and non-Gaussian error distribution problems. In addition, uncertainties in the battery model parameters must be taken into account to describe the battery degradation. In this paper, a novel model-based method combining a Sequential Monte Carlo filter with adaptive control to determine the cell SOC and its electric impedance is presented. The applicability of this dual estimator is verified using measurement data acquired from a commercial LiFePO4 cell. Due to a better handling of the hysteresis problem, results show the benefits of the proposed method against the estimation with an Extended Kalman filter.

  5. Forest Fires, Oil Spills, and Fractal Geometry: An Investigation in Two Parts. Part 2: Using Fractal Complexity to Analyze Mathematical Models.

    ERIC Educational Resources Information Center

    Biehl, L. Charles

    1999-01-01

    Presents an activity that utilizes the mathematical models of forest fires and oil spills that were generated (in the first part of this activity, published in the November 1998 issue) by students using probability and cellular automata. (ASK)

  6. Multiaxial yield surface of transversely isotropic foams: Part I-Modeling

    NASA Astrophysics Data System (ADS)

    Ayyagari, Ravi Sastri; Vural, Murat

    2015-01-01

    A new yield criterion is proposed for transversely isotropic solid foams. Its derivation is based on the hypothesis that the yielding in foams is driven by the total strain energy density, rather than a completely phenomenological approach. This allows defining the yield surface with minimal number of parameters and does not require complex experiments. The general framework used leads to the introduction of new scalar measures of stress and strain (characteristic stress and strain) for transversely isotropic foams. Furthermore, the central hypothesis that the total strain energy density drives yielding in foams ascribes to the characteristic stress an analogous role of von Mises stress in metal plasticity. Unlike the overwhelming majority of yield models in literature the proposed model recognizes the tension-compression difference in yield behavior of foams through a linear mean stress term. Predictions of the proposed yield model are in excellent agreement with the results of uniaxial, biaxial and triaxial FE analyses implemented on both isotropic and transversely isotropic Kelvin foam models.

  7. DEVELOPMENT OF A LAND-SURFACE MODEL PART I: APPLICATION IN A MESOSCALE METEOROLOGY MODEL

    EPA Science Inventory

    Parameterization of land-surface processes and consideration of surface inhomogeneities are very important to mesoscale meteorological modeling applications, especially those that provide information for air quality modeling. To provide crucial, reliable information on the diurn...

  8. A semimetal model of the normal state magnetic susceptibility and transport properties of Ba(Fe1-xCox)2As2

    SciTech Connect

    Sales, Brian C; McGuire, Michael A; Sefat, A. S.; Mandrus, David

    2010-01-01

    A simple two band model is used to describe the magnitude and temperature dependence of the magnetic susceptibility, Hall coefficient, resistivity and Seebeck data from undoped and Co doped BaFe2As2. Overlapping rigid parabolic electron and hole bands are considered as a model of the electronic structure of the FeAs-based semimetals. The model has only three parameters: the electron and hole effective masses and the position of the valence band maximum with respect to the conduction band minimum. The model is able to reproduce in a semiquantitative fashion the magnitude and temperature dependence of many of the normal state magnetic and transport data from the FeAs-type materials, including the ubiquitous increase in the magnetic susceptibility with increasing temperature.

  9. Phase at Nd/Nd-Fe-B Interface: A First-Principles Modeling

    NASA Astrophysics Data System (ADS)

    Chen, Ying; Saengdeejing, Arkapol; Matsuura, Masashi; Sugimoto, Satoshi

    2014-07-01

    The development of advanced Nd-Fe-B permanent magnet materials with high coercivity draws much attention to the relation between coercivity and microstructure at the grain boundaries of the magnets. A disordered face-centered cubic (fcc)-NdO x phase formed at the interface of Nd/Nd-Fe-B is observed, and it is believed to take an important role in coercivity generation. To have a thorough understanding of the formation mechanism of this particular oxide and its relation to the surface coercivity, a ground state analysis for whole oxygen concentration in Nd-O has been performed by combining the LSDA + U and the cluster expansion method. Systematic calculations revealed that a sequent fcc-based structure formed by introducing oxygen vacancies into NdO is stable in almost all the 0-50% oxygen concentration range, whereas in a series of hexagonal close-packed (hcp)-based structures developed from hP5-Nd2O3 no stable structure is observed, which coincides with the experimental measurement very well. A further analysis of formation energies and relevant changes in electronic structures of single oxygen vacancy in various structures revealed the insight of such fcc-based phase formation and further explained the relation between the phase stability and coercivity.

  10. Synthesis, characterization and application of iron (II, III) oxide (Fe3O4) magnetic nanoparticles in mimic of wound healing model

    NASA Astrophysics Data System (ADS)

    Konyala, Divya

    The research study focused on synthesis, characterization and applications of Fe3O4 core-shelled magnetic nanomaterials. This Fe3O4 magnetic nanomaterials will be prepared by using cost effective and convenient wet-chemistry method and will encapsulated using aqueous extracts of medicinal natural products. Three natural products namely Symplocos racemosa, Picrorhiza kurroa and Butea monosperma used to encapsulate Fe3O 4 MNMs due to their scope to reduce the risk of cancer, improves health, increase energy and enhance the immunity. These three medicinal natural products are synthesize by using water as a solvents to derive its active constituents, which will further used to functionalize the magnetic nanomaterials. The magnetic nanoparticles characterization studies performed using X-ray powder diffraction, Scanning electron microscope, Transmission electron microscope, Ultraviolet-visible spectroscopy, Fourier Transform Infrared spectroscopy (FT-IR) and Magnetic property. Fe3O4 magnetic nanomaterials biological activity was tested on Gram-negative bacteria (Escherichia coli). The results pointed out that, due to the adequate coating of Fe 3O4 (Iron Oxide) core by the medicinal chemical constituents from the natural products, the absorption of Fe3O4 magnetic nanomaterials was not detected in the UV-VIS Spectroscopy. TEM images showed that Fe3O4 coated with natural product extract in core-shelled structure, and the size of the particle ranges from 6 nm to 10 nm. Fourier Transform Infrared spectroscopy (FT-IR) was performed to determine the nature of chemicals present in natural extracts and functionalized Fe3O 4 magnetic nanomaterials. The model of wound healing mimic and antibacterial activity performed on gram-negative (Escherichia coli), indicating steady increasing cell growth after adding Fe3O4 MNMs. It was also found that MNMs synthesized at high temperatures shows less wound healing activity, when compared to MNMs prepared at room temperature due to formation

  11. Transportation Sector Model of the National Energy Modeling System. Volume 2 -- Appendices: Part 2

    SciTech Connect

    1998-01-01

    The attachments contained within this appendix provide additional details about the model development and estimation process which do not easily lend themselves to incorporation in the main body of the model documentation report. The information provided in these attachments is not integral to the understanding of the model`s operation, but provides the reader with opportunity to gain a deeper understanding of some of the model`s underlying assumptions. There will be a slight degree of replication of materials found elsewhere in the documentation, made unavoidable by the dictates of internal consistency. Each attachment is associated with a specific component of the transportation model; the presentation follows the same sequence of modules employed in Volume 1. The following attachments are contained in Appendix F: Fuel Economy Model (FEM)--provides a discussion of the FEM vehicle demand and performance by size class models; Alternative Fuel Vehicle (AFV) Model--describes data input sources and extrapolation methodologies; Light-Duty Vehicle (LDV) Stock Model--discusses the fuel economy gap estimation methodology; Light Duty Vehicle Fleet Model--presents the data development for business, utility, and government fleet vehicles; Light Commercial Truck Model--describes the stratification methodology and data sources employed in estimating the stock and performance of LCT`s; Air Travel Demand Model--presents the derivation of the demographic index, used to modify estimates of personal travel demand; and Airborne Emissions Model--describes the derivation of emissions factors used to associate transportation measures to levels of airborne emissions of several pollutants.

  12. Mathematical modeling of cement paste microstructure by mosaic pattern. Part II. Application

    SciTech Connect

    Tennis, P.D.; Xi, Y.; Jennings, H.M.

    1997-07-01

    A model based on mosaic pattern analysis is shown to have the potential to describe the complex shapes and spatial distribution of phases in the microstructures of multiphase materials. Several characteristics of both micrographs of portland cement pastes and images generated using the few parameters of the model are determined and, for the most part, agreement is good. The advantage is that spatial features of the microstructures can be captured by a few parameters. {copyright} {ital 1997 Materials Research Society.}

  13. Investigation of the Fe3+ centers in perovskite KMgF3 through a combination of ab initio (density functional theory) and semi-empirical (superposition model) calculations

    NASA Astrophysics Data System (ADS)

    Emül, Y.; Erbahar, D.; Açıkgöz, M.

    2015-08-01

    Analyses of the local crystal and electronic structure in the vicinity of Fe3+ centers in perovskite KMgF3 crystal have been carried out in a comprehensive manner. A combination of density functional theory (DFT) and a semi-empirical superposition model (SPM) is used for a complete analysis of all Fe3+ centers in this study for the first time. Some quantitative information has been derived from the DFT calculations on both the electronic structure and the local geometry around Fe3+ centers. All of the trigonal (K-vacancy case, K-Li substitution case, and normal trigonal Fe3+ center case), FeF5O cluster, and tetragonal (Mg-vacancy and Mg-Li substitution cases) centers have been taken into account based on the previously suggested experimental and theoretical inferences. The collaboration between the experimental data and the results of both DFT and SPM calculations provides us to understand most probable structural model for Fe3+ centers in KMgF3.

  14. On a Model-Independent Representation for the Real Part of the Elastic Hadron Amplitude

    SciTech Connect

    Fagundes, D. A.; Menon, M. J.

    2010-11-12

    The applicability of Martin's Real Part Formula in model-independent analysis of elastic proton-proton scattering is discussed. Good reproduction of all the differential cross section data at high-energies (19.4-62.5 GeV) is obtained through an empirical parametrization for the imaginary part of the amplitude and the use of a representation for the Martin's formula without the scaling property. According to the fit results, the scattering amplitude is predominantly imaginary, except at the dip region. One zero (change of sign) is observed in the imaginary part of the amplitude (dip region) and two zeros in the real part (at small and intermediate values of the momentum transfer).

  15. Aeroservoelastic Testing of Free Flying Wind Tunnel Models Part 2: A Centerline Supported Fullspan Model Tested for Gust Load Alleviation

    NASA Technical Reports Server (NTRS)

    Scott, Robert C.; Vetter, Travis K.; Penning, Kevin B.; Coulson, David A.; Heeg, Jennifer

    2014-01-01

    This is part 2 of a two part document. Part 1 is titled: "Aeroservoelastic Testing of Free Flying Wind Tunnel Models Part 1: A Sidewall Supported Semispan Model Tested for Gust Load Alleviation and Flutter Suppression." A team comprised of the Air Force Research Laboratory (AFRL), Boeing, and the NASA Langley Research Center conducted three aeroservoelastic wind tunnel tests in the Transonic Dynamics Tunnel to demonstrate active control technologies relevant to large, flexible vehicles. In the first of these three tests, a full-span, aeroelastically scaled, wind tunnel model of a joined wing SensorCraft vehicle was mounted to a force balance to acquire a basic aerodynamic data set. In the second and third tests, the same wind tunnel model was mated to a new, two degree of freedom, beam mount. This mount allowed the full-span model to translate vertically and pitch. Trimmed flight at10 percent static margin and gust load alleviation were successfully demonstrated. The rigid body degrees of freedom required that the model be flown in the wind tunnel using an active control system. This risky mode of testing necessitated that a model arrestment system be integrated into the new mount. The safe and successful completion of these free-flying tests required the development and integration of custom hardware and software. This paper describes the many systems, software, and procedures that were developed as part of this effort. The balance and free flying wind tunnel tests will be summarized. The design of the trim and gust load alleviation control laws along with the associated results will also be discussed.

  16. Optical and radiometric models of the NOMAD instrument part II: the infrared channels - SO and LNO.

    PubMed

    Thomas, I R; Vandaele, A C; Robert, S; Neefs, E; Drummond, R; Daerden, F; Delanoye, S; Ristic, B; Berkenbosch, S; Clairquin, R; Maes, J; Bonnewijn, S; Depiesse, C; Mahieux, A; Trompet, L; Neary, L; Willame, Y; Wilque, V; Nevejans, D; Aballea, L; Moelans, W; De Vos, L; Lesschaeve, S; Van Vooren, N; Lopez-Moreno, J-J; Patel, M R; Bellucci, G

    2016-02-22

    NOMAD is a suite of three spectrometers that will be launched in 2016 as part of the joint ESA-Roscosmos ExoMars Trace Gas Orbiter mission. The instrument contains three channels that cover the IR and UV spectral ranges and can perform solar occultation, nadir and limb observations, to detect and map a wide variety of Martian atmospheric gases and trace species. Part I of this work described the models of the UVIS channel; in this second part, we present the optical models representing the two IR channels, SO (Solar Occultation) and LNO (Limb, Nadir and Occultation), and use them to determine signal to noise ratios (SNRs) for many expected observational cases. In solar occultation mode, both the SO and LNO channel exhibit very high SNRs >5000. SNRs of around 100 were found for the LNO channel in nadir mode, depending on the atmospheric conditions, Martian surface properties, and observation geometry. PMID:27333621

  17. Knowledge representation and qualitative simulation of salmon redd functioning. Part I: qualitative modeling and simulation.

    PubMed

    Guerrin, F; Dumas, J

    2001-02-01

    This work aims at representing empirical knowledge of freshwater ecologists on the functioning of salmon redds (spawning areas of salmon) and its impact on mortality of early stages. For this, we use Qsim, a qualitative simulator. In this first part, we provide unfamiliar readers with the underlying qualitative differential equation (QDE) ontology of Qsim: representing quantities, qualitative variables, qualitative constraints, QDE structure. Based on a very simple example taken of the salmon redd application, we show how informal biological knowledge may be represented and simulated using an approach that was first intended to analyze qualitatively ordinary differential equations systems. A companion paper (Part II) gives the full description and simulation of the salmon redd qualitative model. This work was part of a project aimed at assessing the impact of the environment on salmon populations dynamics by the use of models of processes acting at different levels: catchment, river, and redds. Only the latter level is dealt with in this paper. PMID:11267737

  18. Coupled Model for Carbon Partitioning from Martensite into Austenite During the Quenching Process in Fe-C Steels

    NASA Astrophysics Data System (ADS)

    Liu, Peixing; Zhu, Bin; Wang, Yilin; Zhang, Yisheng

    2016-08-01

    In this paper, a coupled model for carbon partitioning from martensite into austenite during the quenching process in Fe-C steels is constructed where the carbon is permitted to partition while the martensite is continuously forming. A diffusion model of carbon at the `martensite/austenite interface' is created where the interface does not move during the carbon partitioning process, and the driving force for carbon partitioning originates from the chemical potential difference. The results show that the martensitic transformation and carbon partitioning affect each other, and that the cooling rate between the martensite start temperature ( M s) and room temperature has a major effect on the volume fraction of the final retained austenite. The simulation results are shown to be in good agreement with experiments.

  19. Coupled Model for Carbon Partitioning from Martensite into Austenite During the Quenching Process in Fe-C Steels

    NASA Astrophysics Data System (ADS)

    Liu, Peixing; Zhu, Bin; Wang, Yilin; Zhang, Yisheng

    2016-05-01

    In this paper, a coupled model for carbon partitioning from martensite into austenite during the quenching process in Fe-C steels is constructed where the carbon is permitted to partition while the martensite is continuously forming. A diffusion model of carbon at the `martensite/austenite interface' is created where the interface does not move during the carbon partitioning process, and the driving force for carbon partitioning originates from the chemical potential difference. The results show that the martensitic transformation and carbon partitioning affect each other, and that the cooling rate between the martensite start temperature (M s) and room temperature has a major effect on the volume fraction of the final retained austenite. The simulation results are shown to be in good agreement with experiments.

  20. Reduction of N2 by Fe2+ via Homogeneous and Heterogeneous Reactions Part 2: The Role of Metal Binding in Activating N2 for Reduction; a Requirement for Both Pre-biotic and Biological Mechanisms

    NASA Astrophysics Data System (ADS)

    Wander, Matthew C. F.; Kubicki, James D.; Schoonen, Martin A. A.

    2008-06-01

    Nitrogen reduction by ferrous iron has been suggested as an important mechanism in the formation of ammonia on pre-biotic Earth. This paper examines the effects of adsorption of ferrous iron onto a goethite (α-FeOOH) substrate on the thermodynamic driving force and rate of a ferrous iron-mediated reduction of N2 as compared with the homogeneous aqueous reaction. Utilizing density functional theory and Marcus Theory of proton coupled electron transfer reactions, the following two reactions were studied: {text{Fe}}^{2 + } _{left( {{text{aq}}} right)} + {text{N}}_{2left( {{text{aq}}} right)} + {text{H}}_2 {text{O}}_{left( {{text{aq}}} right)} to {text{N}}_2 {text{H}}^ bullet + {text{FeOH}}^{2 + } _{left( {{text{aq}}} right)} and equiv {text{Fe}}^{2 + } _{left( {{text{ads}}} right)} + {text{N}}_{2left( {{text{aq}}} right)} + 2{text{H}}_2 {text{O}}_{left( {{text{aq}}} right)} to {text{N}}_2 {text{H}}^ bullet + α - {text{FeOOH}}_{left( {text{s}} right)} + 2{text{H}}^ + _{left( {{text{aq}}} right)} Although the rates of both reactions were calculated to be approximately zero at 298 K, the model results suggest that adsorption alters the thermodynamic driving force for the reaction but has no other effect on the direct electron transfer kinetics. Given that simply altering the thermodynamic driving force will not reduce dinitrogen, we can make mechanistic connections between possible prebiotic pathways and biological N2 reduction. The key to reduction in both cases is N2 adsorption to multiple transition metal centers with competitive H2 production.

  1. A Four-Part Model of Autonomy during Emerging Adulthood: Associations with Adjustment

    ERIC Educational Resources Information Center

    Lamborn, Susie D.; Groh, Kelly

    2009-01-01

    We found support for a four-part model of autonomy that links connectedness, separation, detachment, and agency to adjustment during emerging adulthood. Based on self-report surveys of 285 American college students, expected associations among the autonomy variables were found. In addition, agency, as measured by self-reliance, predicted lower…

  2. 40 CFR Appendix W to Part 51 - Guideline on Air Quality Models

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... clear from the needs expressed by the States and EPA Regional Offices, by many industries and trade... 51—Guideline on Air Quality Models Preface a. Industry and control agencies have long expressed a....0Bibliography 12.0References Appendix A to Appendix W of 40 CFR Part 51—Summaries of Preferred Air...

  3. 40 CFR Appendix W to Part 51 - Guideline on Air Quality Models

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... clear from the needs expressed by the States and EPA Regional Offices, by many industries and trade... 51—Guideline on Air Quality Models Preface a. Industry and control agencies have long expressed a....0Bibliography 12.0References Appendix A to Appendix W of 40 CFR Part 51—Summaries of Preferred Air...

  4. 40 CFR Appendix W to Part 51 - Guideline on Air Quality Models

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... clear from the needs expressed by the States and EPA Regional Offices, by many industries and trade... 51—Guideline on Air Quality Models Preface a. Industry and control agencies have long expressed a....0Bibliography 12.0References Appendix A to Appendix W of 40 CFR Part 51—Summaries of Preferred Air...

  5. 40 CFR Appendix W to Part 51 - Guideline on Air Quality Models

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... clear from the needs expressed by the States and EPA Regional Offices, by many industries and trade... 51—Guideline on Air Quality Models Preface a. Industry and control agencies have long expressed a....0Bibliography 12.0References Appendix A to Appendix W of 40 CFR Part 51—Summaries of Preferred Air...

  6. 31 CFR Appendix A to Part 208 - Model Disclosure for Use Until ETA SM Becomes Available

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Model Disclosure for Use Until ETA SM Becomes Available A Appendix A to Part 208 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) FISCAL SERVICE, DEPARTMENT OF THE TREASURY FINANCIAL MANAGEMENT SERVICE MANAGEMENT OF FEDERAL AGENCY DISBURSEMENTS Pt....

  7. 31 CFR Appendix B to Part 208 - Model Disclosure for Use After ETA SM Becomes Available

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Model Disclosure for Use After ETA SM Becomes Available B Appendix B to Part 208 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) FISCAL SERVICE, DEPARTMENT OF THE TREASURY FINANCIAL MANAGEMENT SERVICE MANAGEMENT OF FEDERAL AGENCY DISBURSEMENTS Pt....

  8. 42 CFR Appendix to Part 54a - Model Notice of Individuals Receiving Substance Abuse Services

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Model Notice of Individuals Receiving Substance Abuse Services Appendix to Part 54a Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS CHARITABLE CHOICE REGULATIONS APPLICABLE TO STATES, LOCAL GOVERNMENTS AND RELIGIOUS ORGANIZATIONS RECEIVING DISCRETIONARY...

  9. High-resolution measurements, line identification, and spectral modeling of K{alpha} transitions in Fe XVIII-XXV

    SciTech Connect

    Beiersdorfer, P.; Phillips, T.; Jacobs, V.L.; Hill, K.W.; Bitter, M.; von Goeler, S.; Kahn, S.M.

    1992-11-01

    The iron K{alpha} emission spectrum covering the wavelength region from 1.840 to 1.940 {Angstrom} is analyzed. Measurements are made with a high-resolution Bragg crystal spectrometer on the Princeton Large Torus (PLT) tokamak for plasma conditions which closely resemble those of solar flares. A total of 40 features are identified consisting of either single or multiple lines from eight charge states in iron, Fe XVIII through Fe XXV, and their wavelengths are determined with an accuracy of 0.1--0.4 m{Angstrom}. Many of these features are identified for the first time. In the interpretation of our observations we rely on model calculations that determine the ionic species abundances from electron density and temperature profiles measured independently with non-spectroscopic techniques and that incorporate theoretical collisional excitation and dielectronic recombination rates resulting in the excitation of the 1s2s{sup r}2p{sup s} configurations. The model calculations also include the effect of diffusive ion transport. Good overall agreement between the model calculations and the observations is obtained, which gives us confidence in our line identifications and spectral modeling capabilities. The results are compared with earlier analyses of the K{alpha} emission from the Sun. While many similarities are found, a few differences arise from the somewhat higher electron density in tokamak plasmas (10{sup 13} cm{sup {minus}3}), which affects the fine-structure level populations of the ground states of the initial ion undergoing electron-impact excitation or dielectronic recombination. We also find that several spectral features are comprised of different transitions from those reported in earlier analyses of solar data.

  10. High-resolution measurements, line identification, and spectral modeling of K[alpha] transitions in Fe XVIII-XXV

    SciTech Connect

    Beiersdorfer, P.; Phillips, T. ); Jacobs, V.L. . Condensed Matter and Radiation Sciences Div.); Hill, K.W.; Bitter, M.; von Goeler, S. . Plasma Physics Lab.); Kahn, S.M. )

    1992-11-01

    The iron K[alpha] emission spectrum covering the wavelength region from 1.840 to 1.940 [Angstrom] is analyzed. Measurements are made with a high-resolution Bragg crystal spectrometer on the Princeton Large Torus (PLT) tokamak for plasma conditions which closely resemble those of solar flares. A total of 40 features are identified consisting of either single or multiple lines from eight charge states in iron, Fe XVIII through Fe XXV, and their wavelengths are determined with an accuracy of 0.1--0.4 m[Angstrom]. Many of these features are identified for the first time. In the interpretation of our observations we rely on model calculations that determine the ionic species abundances from electron density and temperature profiles measured independently with non-spectroscopic techniques and that incorporate theoretical collisional excitation and dielectronic recombination rates resulting in the excitation of the 1s2s[sup r]2p[sup s] configurations. The model calculations also include the effect of diffusive ion transport. Good overall agreement between the model calculations and the observations is obtained, which gives us confidence in our line identifications and spectral modeling capabilities. The results are compared with earlier analyses of the K[alpha] emission from the Sun. While many similarities are found, a few differences arise from the somewhat higher electron density in tokamak plasmas (10[sup 13] cm[sup [minus]3]), which affects the fine-structure level populations of the ground states of the initial ion undergoing electron-impact excitation or dielectronic recombination. We also find that several spectral features are comprised of different transitions from those reported in earlier analyses of solar data.

  11. 37 CFR 1.91 - Models or exhibits not generally admitted as part of application or patent.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... paragraph (a) of this section, a model, working model, or other physical exhibit may be required by the... admitted as part of application or patent. (a) A model or exhibit will not be admitted as part of the... including: (i) The fee set forth in § 1.17(h); and (ii) An explanation of why entry of the model or...

  12. 37 CFR 1.91 - Models or exhibits not generally admitted as part of application or patent.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... paragraph (a) of this section, a model, working model, or other physical exhibit may be required by the... admitted as part of application or patent. (a) A model or exhibit will not be admitted as part of the... including: (i) The fee set forth in § 1.17(h); and (ii) An explanation of why entry of the model or...

  13. Tutorial on agent-based modeling and simulation. Part 2 : how to model with agents.

    SciTech Connect

    Macal, C. M.; North, M. J.; Decision and Information Sciences

    2006-01-01

    Agent-based modeling and simulation (ABMS) is a new approach to modeling systems comprised of interacting autonomous agents. ABMS promises to have far-reaching effects on the way that businesses use computers to support decision-making and researchers use electronic laboratories to do research. Some have gone so far as to contend that ABMS is a new way of doing science. Computational advances make possible a growing number of agent-based applications across many fields. Applications range from modeling agent behavior in the stock market and supply chains, to predicting the spread of epidemics and the threat of bio-warfare, from modeling the growth and decline of ancient civilizations to modeling the complexities of the human immune system, and many more. This tutorial describes the foundations of ABMS, identifies ABMS toolkits and development methods illustrated through a supply chain example, and provides thoughts on the appropriate contexts for ABMS versus conventional modeling techniques.

  14. Development of a model electronic Hamiltonian for understanding electronic relaxation dynamics of [Fe(bpy){sub 3}]{sup 2+} through molecular dynamics simulations

    SciTech Connect

    Iuchi, Satoru; Koga, Nobuaki

    2015-12-31

    A model electronic Hamiltonian of [Fe(bpy){sub 3}]{sup 2+}, which was recently refined for use in molecular dynamics simulations, is reviewed with some additional results. In particular, the quality of the refined model Hamiltonian is examined in terms of the vibrational frequencies and solvation structures of the lowest singlet and quintet states.

  15. Towards a Predictive Thermodynamic Model of Oxidation States of Uranium Incorporated in Fe (hydr) oxides

    SciTech Connect

    Bagus, Paul S.

    2013-01-01

    The theoretical research in this project has been directed toward the interpretation of core-level spectroscopies for systems relevant to the project. For the initial efforts, the focus of our theoretical simulations has been the interpretation of laboratory and synchrotron X-Ray Photoemission Spectra, XPS. In more recent efforts, an increasing emphasis has been placed on developing transparent understandings of X-Ray Adsorption Spectra, XAS . For the XAS, the principal concern is for the near-edge features, either just below or just above, an ionization limit or edge, which are described as Near-Edge X-Ray Adsorption Fine Structure, NEXAFS. In particular, a priority has involved the analysis and interpretation of XPS and NEXAFS spectra, especially of Fe and U systems, as measured by our PNNL collaborators. The overall objective of our theoretical studies is to establish connections between features of the spectra and their origin in the electronic structure of the materials. The efforts for the analysis of XPS have been reviewed in a paper by the PI, C. J. Nelin, and E. S. Ilton from PNNL on “The interpretation of XPS spectra: Insights into materials properties”, Surf. Sci. Reports, 68, 273 (2013). Two materials properties of special interest have been the degree of ionicity and the character of the covalent bonding in a range of oxides formed with transition metal, lanthanide, and actinide cations. Since the systems treated have electrons in open shells, it has been necessary to determine the energetics and the character of the angular momentum coupling of the open shell electrons. In particular, we have established methods for the treatment of the “intermediate coupling” which arises when the system is between the limit of Russell-Saunders multiplets, and the limit of j-j coupling where the spin-orbit splittings of single electrons dominate. A recent paper by the PI, and M. J. Sassi, and K. M. Rosso, (both at PNNL) “Intermediate Coupling For Core

  16. NEAMS-ATF M3 Milestone Report: Literature Review of Modeling of Radiation-Induced Swelling in Fe-Cr-Al Steels

    SciTech Connect

    Bai, Xianming; Biner, Suleyman Bulent; Jiang, Chao

    2015-12-01

    Fe-Cr-Al steels are proposed as accident-tolerant-fuel (ATF) cladding materials in light water reactors due to their excellent oxidation resistance at high temperatures. Currently, the understanding of their performance in reactor environment is still limited. In this review, firstly we reviewed the experimental studies of Fe-Cr-Al based alloys with particular focus on the radiation effects in these alloys. Although limited data are available in literature, several previous and recent experimental studies have shown that Fe-Cr-Al based alloys have very good void swelling resistance at low and moderate irradiation doses but the growth of dislocation loops is very active. Overall, the behavior of radiation damage evolution is similar to that in Fe-Cr ferritic/martensitic alloys. Secondly, we reviewed the rate theory-based modeling methods for modeling the coevolution of voids and dislocation loops in materials under irradiation such as Frenkel pair three-dimensional diffusion model (FP3DM) and cluster dynamics. Finally, we summarized and discussed our review and proposed our future plans for modeling radiation damage in Fe-Cr-Al based alloys.

  17. Growth of FePt encapsulated carbon nanotubes by thermal chemical vapor deposition

    SciTech Connect

    Fujiwara, Yuji Kaneko, Tetsuya; Hori, Kenta; Takase, Sho; Sato, Hideki; Maeda, Kohji; Kobayashi, Tadashi; Kato, Takeshi; Iwata, Satoshi; Jimbo, Mutsuko

    2014-03-15

    FePt encapsulated carbon nanotubes (CNTs) were grown by thermal chemical vapor deposition using an Fe/Pt bilayer catalyst. The CNTs were grown according to the base growth model. Selected area electron diffraction results revealed that the encapsulated particles were A1-FePt, L1{sub 0}-FePt, and Fe{sub 3}PtC. The crystal structures of particles found at the root parts of CNTs were not able to be identified, however. The layered structure of catalytic films seemed to be responsible for the difference in Pt content between particles found at tip and root parts of CNTs. Approximately 60% of CNTs grown at 800 °C had particles at their tip parts, compared to only 30% when the growth temperature was 700 °C, indicating that higher process temperatures promote particle encapsulation in CNTs.

  18. Exchange coupling and magnetic anisotropy at Fe/FePt interfaces

    NASA Astrophysics Data System (ADS)

    Aas, C. J.; Hasnip, P. J.; Cuadrado, R.; Plotnikova, E. M.; Szunyogh, L.; Udvardi, L.; Chantrell, R. W.

    2013-11-01

    We perform fully relativistic first-principles calculations of the exchange interactions and the magnetocrystalline anisotropy energy (MAE) in an Fe/FePt/Fe sandwich system in order to elucidate how the presence of Fe/FePt (soft/hard magnetic) interfaces impacts on the magnetic properties of Fe/FePt/Fe multilayers. Throughout our study we make comparisons between a geometrically unrelaxed system and a geometrically relaxed system. We observe that the Fe layer at the Fe/FePt interface plays a crucial role inasmuch as its (isotropic) exchange coupling to the soft (Fe) phase of the system is substantially reduced. Moreover, this interfacial Fe layer has a substantial impact on the MAE of the system. We show that the MAE of the FePt slab, including the contribution from the Fe/FePt interface, is dominated by anisotropic intersite exchange interactions. Our calculations indicate that the change in the MAE of the FePt slab with respect to the corresponding bulk value is negative, i.e., the presence of Fe/FePt interfaces appears to reduce the perpendicular MAE of the Fe/FePt/Fe system. However, for the relaxed system, this reduction is marginal. It is also shown that the relaxed system exhibits a reduced interfacial exchange. Using a simple linear chain model, we demonstrate that the reduced exchange leads to a discontinuity in the magnetization structure at the interface.

  19. A model for plasticity kinetics and its role in simulating the dynamic behavior of Fe at high strain rates

    SciTech Connect

    Colvin, J D; Minich, R W; Kalantar, D H

    2007-03-29

    The recent diagnostic capability of the Omega laser to study solid-solid phase transitions at pressures greater than 10 GPa and at strain rates exceeding 10{sup 7} s{sup -1} has also provided valuable information on the dynamic elastic-plastic behavior of materials. We have found, for example, that plasticity kinetics modifies the effective loading and thermodynamic paths of the material. In this paper we derive a kinetics equation for the time-dependent plastic response of the material to dynamic loading, and describe the model's implementation in a radiation-hydrodynamics computer code. This model for plasticity kinetics incorporates the Gilman model for dislocation multiplication and saturation. We discuss the application of this model to the simulation of experimental velocity interferometry data for experiments on Omega in which Fe was shock compressed to pressures beyond the {alpha}-to-{var_epsilon} phase transition pressure. The kinetics model is shown to fit the data reasonably well in this high strain rate regime and further allows quantification of the relative contributions of dislocation multiplication and drag. The sensitivity of the observed signatures to the kinetics model parameters is presented.

  20. Modelling Escherichia coli concentration in a wastewater reservoir using an operational parameter MRT%FE and first order kinetics.

    PubMed

    Cirelli, Giuseppe Luigi; Consoli, Simona; Juanicó, Marcelo

    2009-01-01

    The operational parameter MRT%FE, representing the mean residence time of different ages fractions of effluent within a completely mixed reactor, was evaluated and integrated with first order kinetics. The parameter was used to model Escherichia coli concentrations in a municipal wastewater reservoir managed under different operating conditions (continuous and discontinuous). The study was conducted during 2004-2005 in a reservoir receiving effluents from the activated sludge treatment plant of Caltagirone (Eastern Sicily - Italy). The analytical approach is applied to the hydraulic state variables of the system (daily stored volumes, inlet and outlet flows), and the physical-chemical (pH, temperature, EC, TSS, BOD(5), COD) and bacteriological wastewater parameters (E. coli, FC, FS). In order to evaluate the reliability of the proposed approach, predicted E. coli concentrations within the reservoir were compared with measured ones by the correlation coefficient, F-test and Sperman's index. The study included the evaluation of die-off coefficient K(T) (d(-1)), light extinction coefficient K (m(-1)) and their relationships with climatic factors. Results of the study confirm that E. coli removal is related to the fractions of fresh effluent remaining each day within the reservoir with MRT%FE of about 5-8d, significantly lower than the nominal detention time (about 27d). The E. coli die-off coefficient (K(T)) was higher during system discontinuous operations and correlated with incident solar radiation and water temperature. PMID:18222594