WorldWideScience

Sample records for ag-rich fcc phases

  1. Angular distortive matrices of phase transitions in the fcc-bcc-hcp system

    OpenAIRE

    Cayron, Cyril

    2016-01-01

    This work generalizes the one-step model previously developed on fcc-bcc martensitic transformations to the larger family of phase transitions in the fcc-bcc-hcp system. The angular distortive matrices are calculated for the bcc-fcc, bcc-hcp and fcc-hcp transitions, and for fcc-fcc mechanical twinning. The analytical expressions of the continuous atomic displacements, lattice distortion and lattice correspondence matrices result directly from the orientation relationships; the unique assumpti...

  2. Phase-field-crystal model for fcc ordering.

    Science.gov (United States)

    Wu, Kuo-An; Adland, Ari; Karma, Alain

    2010-06-01

    We develop and analyze a two-mode phase-field-crystal model to describe fcc ordering. The model is formulated by coupling two different sets of crystal density waves corresponding to and reciprocal lattice vectors, which are chosen to form triads so as to produce a simple free-energy landscape with coexistence of crystal and liquid phases. The feasibility of the approach is demonstrated with numerical examples of polycrystalline and (111) twin growth. We use a two-mode amplitude expansion to characterize analytically the free-energy landscape of the model, identifying parameter ranges where fcc is stable or metastable with respect to bcc. In addition, we derive analytical expressions for the elastic constants for both fcc and bcc. Those expressions show that a nonvanishing amplitude of [200] density waves is essential to obtain mechanically stable fcc crystals with a nonvanishing tetragonal shear modulus (C11-C12)/2. We determine the model parameters for specific materials by fitting the peak liquid structure factor properties and solid-density wave amplitudes following the approach developed for bcc [K.-A. Wu and A. Karma, Phys. Rev. B 76, 184107 (2007)]. This procedure yields reasonable predictions of elastic constants for both bcc Fe and fcc Ni using input parameters from molecular dynamics simulations. The application of the model to two-dimensional square lattices is also briefly examined.

  3. First-principles calculations of free energies of unstable phases: the case of fcc W.

    Science.gov (United States)

    Ozolins, V

    2009-02-13

    Ab initio molecular dynamics simulations are used to solve the long-standing problem of calculating the free energies of unstable phases, such as fcc W. We find that fcc W is mechanically unstable with respect to long-wavelength shear at all temperatures considered (T>2500 K), while the short-wavelength phonon modes are anharmonically stabilized. The calculated fcc-bcc enthalpy and entropy differences at T=3500 K (308 meV and 0.74k_{B} per atom, respectively) agree well with the recent values derived from analysis of experimental data.

  4. Nucleation of hcp and fcc phases in bcc iron under uniform compression: classical molecular dynamics simulations.

    Science.gov (United States)

    Wang, B T; Shao, J L; Zhang, G C; Li, W D; Zhang, P

    2010-11-03

    By classical molecular dynamics simulations employing an embedded atom method potential, we have simulated the bcc to hcp/fcc structural transition in single-crystal iron under uniform compression. Results showed that the transition pressure is different from uniaxial compression and shock loading. The transformation occurs on a picosecond timescale and the transition time decreases along with the increase of pressure. The nucleation and growth of the hcp and fcc phases under constant pressure and temperature are analyzed in detail. The nucleation planes, all belonging to the {110}(bcc) family and parallel to the three compression directions [100], [010], and [001], have been observed. About 20% bcc atoms have transformed to fcc phase under pressure just over the critical point, and under higher pressure the fraction of the fcc phase increases steadily to exceed that of the hcp phase. We have investigated the transition mechanism of iron from initial bcc to hcp/fcc and found that the transition mainly consists of compression, rotation, and shuffle.

  5. Atomistic simulation of fcc-bcc phase transition in single crystal A1 under uniform compression

    Institute of Scientific and Technical Information of China (English)

    Li Li; Shao Jian-Li; Li Yan-Fang; Duan Su-Qing; [ Liang Jiu-Qing

    2012-01-01

    By molecular dynamics simulations employing an embedded atom model potential,we investigate the fcc-to-bcc phase transition in single crystal Al,caused by uniform compression.Results show that the fec structure is unstable when the pressure is over 250 GPa,in reasonable agreement with the calculated value through the density functional theory.The morphology evolution of the structural transition and the corresponding transition mechanism are analysed in detail.The bec (011) planes are transited from the fcc (11(1)) plane and the (1(1)1) plane.We suggest that the transition mechanism consists mainly of compression,shear,slid and rotation of the lattice.In addition,our radial distribution function analysis explicitly indicates the phase transition of A1 from fcc phase to bcc structure.

  6. Ferromagnetic Fe on Cu(001) throughout the fcc-like phase: arguing from the viewpoint of the electronic structure.

    Science.gov (United States)

    Donath, M; Pickel, M; Schmidt, A B; Weinelt, M

    2009-04-01

    The scientific enthusiasm for ultrathin Fe films on Cu(001) has now lasted for more than 20 years. Is there ferromagnetic iron with a face-centred cubic (fcc) structure? Does ferromagnetism in Fe hinge on the body-centred cubic (bcc) structure? In this contribution, we try to establish that the electron system gives evidence of ferromagnetic behaviour with fcc-like electronic bands. We examine a crystal-induced surface state, which is characteristic of fcc surface order. Furthermore, we compare electronic signatures of fcc and bcc: the d-band exchange splitting, image-potential-state energies and the work function. We conclude that, from the viewpoint of the electronic structure, Fe on Cu(001) is found to be ferromagnetic throughout the fcc-like phase. This result raises a new question: how much deviation from the relaxed fcc order is acceptable without losing the electronic signature of fcc?

  7. Ag-rich precipitates formation in the Cu–11%Al–10%Mn–3%Ag alloy

    Energy Technology Data Exchange (ETDEWEB)

    Silva, R.A.G., E-mail: galdino.ricardo@gmail.com [Departamento de Ciências Exatas e da Terra, UNIFESP, 09972-270 Diadema, SP (Brazil); Paganotti, A.; Jabase, L. [Departamento de Ciências Exatas e da Terra, UNIFESP, 09972-270 Diadema, SP (Brazil); Adorno, A.T.; Carvalho, T.M.; Santos, C.M.A. [Departamento de Físico-Química, Instituto de Química, UNESP, 14801-970 Araraquara, SP (Brazil)

    2014-12-05

    Highlights: • Cu-rich nanoprecipitates are formed in the presence of Ag. • Bainite precipitation is shifted to higher temperatures in the Cu–11%Al–10%Mn–3%Ag alloy. • The eutectoid α phase and bainite α{sub 1} phase compete by the Cu atoms during precipitation process. - Abstract: The formation of Ag-rich precipitates in the Cu–11%Al–10%Mn–3%Ag alloy initially quenched from 1123 K was analyzed. The results showed that nanoprecipitates of a Cu-rich phase are produced at about 523 K. In higher temperatures these nanoparticles grow and the relative fraction of Ag dissolved in it is increased, thus forming the Ag-rich phase.

  8. Similarity and Difference of Phase Transition FCC – BCC in Calcium and Strontium

    Directory of Open Access Journals (Sweden)

    V.V. Pozhivatenko

    2016-11-01

    Full Text Available Features of polymorphism in calcium and strontium from the point of view of similarity of physical processes which occur at change of pressure and temperatures are researched. The known experimental facts are added calculated (first principal and fit by results which illustrate both similarity, and difference of structural phase transitions FCC – BCC in calcium and strontium. The increase in similarity of the effects connected with polymorphism is shown, at increase both pressure, and temperatures.

  9. Kinetic Study on Liquid-Phase Hydrodesulfurization of FCC Diesel in Tubular Reactors

    Institute of Scientific and Technical Information of China (English)

    Li Hua; Yang Jinliang; Weng Huixin; Wang Jiming

    2015-01-01

    According to the characteristics of FCC diesel, a technology of liquid-phase hydrodesulfurization of the diesel in tubular reactors was proposed and lab-scale experiments were carried out. A kinetic model for the hydrodesulfurization pro-cess was developed and veriifed. The model was utilized to predict the sulfur content of products under different operating conditions. The effects of temperature, space velocity, pressure, and hydrogen concentration on the desulfurization rate were investigated.

  10. Theoretical study of the structural stability for fcc-CHx phases using density functional theory

    Directory of Open Access Journals (Sweden)

    M Dadsetani

    2011-09-01

    Full Text Available  Recently, a new carbon modification, namly n-diamond, have been reported, whose structure is still a matter of debate. It is important to note that the synthesis of n-diamond was carried out in the presence of hydrogen or methan. In this work we evaluate the structural stability of five fcc-CHx phases by means of first-principle calculation. The total energy is obtained as a function of the isotropic, tetragonal and rhombohedral deformations for the bulk structures. First, we analyze the C2H (cuprite, CH (zincblende, CH (rocksalt and CH2 (fluorite structures.It is found that the four systems show a minimum in the total energy for the isotropic and rhombohedral deformations, but are unstable against tetragonal deformation. In the second part, we explore the structural stability of CH2 in the pyrite structure. We find that CH2 (pyrite with the hydrogen atoms defined by the internal parameter u=0.35 and a lattice parameter of 3.766 Å is elastically stable, providing a possible explanation for the experimental observation of fcc-carbon in materials prepared in the presence of hydrogen or methan. In final, we calculate density of states, band structure and EELS spectrum of CH2 (pyrite and compare them with n-diamond.

  11. Electronic structure and magnetism of strained bcc phases across the fcc to bcc transition in ultrathin Fe films

    Science.gov (United States)

    Calloni, Alberto; Berti, Giulia; Bussetti, Gianlorenzo; Fratesi, Guido; Finazzi, Marco; Ciccacci, Franco; Duò, Lamberto

    2016-11-01

    We investigated the electronic structure of the bcc metastable phases involved in the fcc to bcc transition of Fe. Ultrathin Fe films were grown on a 2-monolayer (ML) Ni/W(110) substrate, where a fcc lattice is stabilized at low Fe coverages and the transition proceeds through the formation of bcc nuclei showing a specific "Kurdjumov-Sachs" orientation with the substrate. A comprehensive description of the electronic structure evolution is achieved by combining spin-resolved UV photoemission spectroscopy and ab initio calculations. According to our results, an exchange-split band structure is observed starting from 2 ML of Fe, concomitant with the formation of ferromagnetic bcc nuclei. Continuous modifications are observed in the spin-resolved photoemission spectra for increasing Fe coverage, especially for what concerns the minority states, possibly indicative of the progressive relaxation of the strained bcc phase starting from the bcc/fcc interface.

  12. Pressure-induced fcc to hcp phase transition in Ni-based high entropy solid solution alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, F. X.; Zhao, Shijun; Jin, Ke; Bei, H.; Popov, D.; Park, Changyong; Neuefeind, J. C.; Weber, W. J.; Zhang, Yanwen [Tennessee-K; (ORNL); (CIW)

    2017-01-04

    A pressure-induced phase transition from the fcc to a hexagonal close-packed (hcp) structure was found in NiCoCrFe solid solution alloy starting at 13.5 GPa. The phase transition is very sluggish and the transition did not complete at ~40 GPa. The hcp structure is quenchable to ambient pressure. Only a very small amount (<5%) of hcp phase was found in the isostructural NiCoCr ternary alloy up to the pressure of 45 GPa and no obvious hcp phase was found in NiCoCrFePd system till to 74 GPa. Ab initio Gibbs free energy calculations indicated the energy differences between the fcc and the hcp phases for the three alloys are very small, but they are sensitive to temperature. The critical transition pressure in NiCoCrFe varies from ~1 GPa at room temperature to ~6 GPa at 500 K.

  13. Hyperfine interactions on iron nuclei in the BCC and fractally decomposed BCC/FCC mixed phase iron-gold alloys

    Energy Technology Data Exchange (ETDEWEB)

    Blachowski, A. [Moessbauer Spectroscopy Division, Institute of Physics, Pedagogical University, PL-30-084 Krakow, ul. Podchorazych 2 (Poland); Ruebenbauer, K. [Moessbauer Spectroscopy Division, Institute of Physics, Pedagogical University, PL-30-084 Krakow, ul. Podchorazych 2 (Poland)], E-mail: sfrueben@cyf-kr.edu.pl; Przewoznik, J.; Zukrowski, J. [Solid State Physics Department, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, PL-30-059 Krakow, Al. Mickiewicza 30 (Poland)

    2008-06-30

    Iron-gold alloys for the gold concentration ranging from 1 at.% till 70 at.% were investigated by means of the {sup 57}Fe-14.4 keV Moessbauer spectroscopy, X-ray diffraction and scanning electron microscopy. Samples were prepared by arc melting of the elements, and investigated as cast and after annealing. A single BCC phase is obtained for the gold concentration up to about 3 at.%, while for the higher gold concentration one obtains mixed phase samples containing BCC and FCC phases both. The BCC phase is ferromagnetically ordered at room temperature. Contributions to the charge and spin density on iron atoms in the BCC phase due to the gold impurities were determined up to the second neighbors. The FCC phase is either magnetically ordered at room temperature or it is paramagnetic at the above temperature depending upon iron concentration, as the magnetic transition temperature is increasing with the increasing iron concentration. BCC/FCC mixed phase samples are characterized by very small crystallites (nanoparticles) of both phases. These nanoparticles form hierarchical fractal structures on the scale ranging from more than 1 mm till less than 30 nm.

  14. Calculated Pressure Induced BCC-FCC Phase Transitions in Alkali Metals

    OpenAIRE

    DAĞISTANLI, Hamdi; MUTLU, R. Haluk

    2008-01-01

    The partial occupation numbers and density of states (DOS), and the total DOS at the Fermi level are calculated as a function of reduced atomic volume for bcc and fcc alkali metals employing the linear-muffin-tin-orbital (LMTO) method. By means of the abrupt changes obtained in the partial and total DOS values at the Fermi level, good agreement with regard to experiment were found in predicting the bcc-fcc transition volumes of the alkali metals.

  15. Grain Size Dependence of Uniform Elongation in Single-Phase FCC/BCC Metals

    Science.gov (United States)

    Liu, Haiting; Shen, Yao; Ma, Jiawei; Zheng, Pengfei; Zhang, Lei

    2016-09-01

    We studied the dependence of uniform elongation on grain size in the range of submicron to millimeter for single-phase FCC/BCC metals by reviewing recent experimental results and applying crystal plasticity finite element method simulation. In the order of increasing grain size, uniform elongation can be divided into three stages, namely low elongation stage, nearly constant elongation stage, and decreased elongation with large scatters stage. Low elongation stage features a dramatic increase near the critical grain size at the end of the stage, which is primarily attributed to the emergence of dislocation cell size transition from ultrafine to mid-size grain. Other factors can be neglected due to their negligible influence on overall variation trend. In nearly constant elongation stage, uniform elongation remains unchanged at a high level in general. As grain size keeps growing, uniform elongation starts decreasing and becomes scattered upon a certain grain size, indicating the initiation of decreased elongation with large scatters stage. It is shown that the increase is not linear or smooth but rather sharp at the end of low elongation stage, leading to a wider range in nearly constant elongation stage. The grain size dependence of uniform elongation can serve as a guiding principle for designing small uniaxial tensile specimens for mechanical testing, where size effect matters in most cases.

  16. Computational Fluid Dynamics Simulation of Liquid-Phase FCC Diesel Hydrotreating in Tubular Reactor

    Institute of Scientific and Technical Information of China (English)

    Li Hua; Liu Ningqiang; Zeng Zhiyu; Zou Ying; Wang Jiming

    2015-01-01

    The computational lfuid dynamics (CFD) code, FLUENT, was used to simulate the liquid-phase FCC diesel hy-drotreating tubular reactor with a ceramic membrane tube dispenser. The chemical reaction and reaction heat were added to the model by user-deifned function (UDF), showing the distribution of temperature and content of sulifdes, nitrides, bicyclic aromatics and monocyclic aromatics in different parts of the reaction bed. When the pressure was 6.5 MPa, the amount of mixing hydrogen was 0.84% (m), the space velocity was 2 h-1 and the inlet temperature was 633K, the temperature reached a maximum at a height of 0.15 m, and the range of radial temperature reached its maximum (2.5 K) at a height of 0.15 m. It indicated that the proper ratio of height to diameter of catalyst bed in the tubular reactor was 5-6. The increase of inlet temperature, the mixing hydrogen and the decrease of space velocity led to the decrease in the content of bicyclic aromatics, sulifdes and nitrides, and the increase in monocyclic aromatics content, while the high temperature increased. The results were in good agreement with experimental data, indicating to the high accuracy of the model.

  17. Kinetics study of crystallization with the disorder-bcc-fcc phase transition of charged colloidal dispersions.

    Science.gov (United States)

    Zhou, Hongwei; Xu, Shenghua; Sun, Zhiwei; Du, Xuan; Liu, Lixia

    2011-06-21

    Structure transformation (disorder-bcc-fcc) in charged colloidal dispersions, as a manifestation of the Ostwald's step rule, was confirmed by means of reflection spectrum (RS) measurements in our previous study. By taking advantage of a reflection spectrum containing plenty of information about the crystallization behaviors, time-dependent changes of parameters associated with the crystal structure and composition during the disorder-bcc-fcc transition are reported by treating the data from RS in this article. In addition, Avrami's model is adopted to analyze the transition process and investigate the transition rate. On the basis of the above investigations, associated kinetic features of crystallization with the disorder-bcc-fcc transition are described.

  18. Why FCC

    Science.gov (United States)

    Angele, W.

    1972-01-01

    Summaries are given of design characteristics and various advantages of FCC use. The information is presented in tables that include the following headings: (1) mechanical design, (2) electrical design, (3) manufacturing advantages, (4) inspection and reliability, and (5) cost savings. In addition, the results are summarized of a Saturn 4B FCC-RWC comparison study.

  19. The role of fcc tetrahedral subunits in the phase behavior of medium sized Lennard-Jones clusters.

    Science.gov (United States)

    Saika-Voivod, Ivan; Poon, Louis; Bowles, Richard K

    2010-08-21

    The free energy of a 600-atom Lennard-Jones cluster is calculated as a function of surface and bulk crystallinity in order to study the structural transformations that occur in the core of medium sized clusters. Within the order parameter range studied, we find the existence of two free energy minima at temperatures near freezing. One minimum, at low values of both bulk and surface order, belongs to the liquid phase. The second minimum exhibits a highly ordered core with a disordered surface and is related to structures containing a single fcc-tetrahedral subunit, with an edge length of seven atoms (l=7), located in the particle core. At lower temperatures, a third minimum appears at intermediate values of the bulk order parameter which is shown to be related to the formation of multiple l=6 tetrahedra in the core of the cluster. We also use molecular dynamics simulations to follow a series of nucleation events and find that the clusters freeze to structures containing l=5, 6, 7, and 8 sized tetrahedra as well as those containing no tetrahedral units. The structural correlations between bulk and surface order with the size of the tetrahedral units in the cluster core are examined. Finally, the relationships between the formation of fcc tetrahedral subunits in the core, the phase behavior of medium sized clusters and the nucleation of noncrystalline global structures such as icosahedra and decahedra are discussed.

  20. Oscillatory Phase Behaviour as a Function of Film Thickness due to Confinement in fcc (100) AsB Alloy Thin Films

    Institute of Scientific and Technical Information of China (English)

    倪军; 刘华; 顾秉林

    2001-01-01

    The order-disorder phase transitions in fcc thin films are investigated by using the mean field method. The result shows that there is a significant difference in the phase transitions and surface segregation between the films of even-number and odd-number layers. There are various types of phase transitions involving several ordered phases with spatial variation for the film of even-number layers, while there is only one phase transition for the film of odd-number layers.

  1. Kinetics of Ag-rich precipitates formation in Cu-Al-Ag alloys

    Energy Technology Data Exchange (ETDEWEB)

    Adorno, A.T.; Guerreiro, M.R.; Silva, R.A.G

    2004-06-15

    The kinetics of Ag-rich precipitates formation in the Cu-2 wt.% Al alloy with additions of 2, 4, 6, 8, 10 and 12 wt.% Ag was studied using microhardness changes with temperature and time, differential scanning calorimetry (DSC), differential thermal analysis (DTA), scanning electron microscopy (SEM), optical microscopy (OM), energy dispersive X-ray analysis (EDX) and X-ray diffractometry (XRD). The results indicated that an increase in the Ag content decreases the activation energy for Ag-rich precipitates formation, and that it is possible to estimate the values of the diffusion and nucleation activation energies for the Ag precipitates.

  2. On the mechanically induced crystallization of FCC phases by mechanical milling in ZrAlNiCu bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jiang [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Dalian 116024 (China); Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, F57012 Metz Cedex (France); Grosdidier, Thierry, E-mail: grosdidier@letam.sciences.univ-metz.f [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, F57012 Metz Cedex (France); Allain-Bonasso, Nathalie [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, F57012 Metz Cedex (France); Gaffet, Eric [Nanomaterials Research Group (NRG, UMR CNRS 5060), Site de Sevenans (UTBM), F90010 Belfort Cedex (France); Dong, Chuang [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Dalian 116024 (China)

    2010-08-15

    In the present study, amorphous-nanocrystalline phase transformation induced by mechanical milling of full monolithic bulk metallic glasses (based on Zr{sub 65}Al{sub 7.5}Ni{sub 10}Cu{sub 17.5} and Zr{sub 58}Al{sub 16}Ni{sub 11}Cu{sub 15} alloys) has been investigated using X-ray diffraction as well as transmission electron microscopy. Nanocrystals having an FCC structure and a grain size of several 10 nm precipitate in the early stages of the milling process and remain stable for long milling duration. The structure changes induced by milling give a new insight on the preparation of amorphous-related alloys when using the method of mechanical milling.

  3. Electrical impedance of FCC

    Science.gov (United States)

    Liu, Y. S.

    1972-01-01

    The electrical characteristics of FCC are investigated in the context of multiple transmission lines theory. Analytical expressions for the coefficients of capacitance of conductors in a single cable are obtained. Numerical values calculated with these expressions are in good agreement with experimental data. Crosstalk, attenuation constants and phase angles of the current and voltage in flat conductor cable are also calculated.

  4. Silicide induced surface defects in FePt nanoparticle fcc-to-fct thermally activated phase transition

    Science.gov (United States)

    Chen, Shu; Lee, Stephen L.; André, Pascal

    2016-11-01

    Magnetic nanoparticles (MnPs) are relevant to a wide range of applications including high density information storage and magnetic resonance imaging to name but a few. Among the materials available to prepare MnPs, FePt is attracting growing attention. However, to harvest the strongest magnetic properties of FePt MnPs, a thermal annealing is often required to convert face-centered cubic as synthesized nPs into its tetragonal phase. Rarely addressed are the potential side effects of such treatments on the magnetic properties. In this study, we focus on the impact of silica shells often used in strategies aiming at overcoming MnP coalescence during the thermal annealing. While we show that this shell does prevent sintering, and that fcc-to-fct conversion does occur, we also reveal the formation of silicide, which can prevent the stronger magnetic properties of fct-FePt MnPs from being fully realised. This report therefore sheds lights on poorly investigated and understood interfacial phenomena occurring during the thermal annealing of MnPs and, by doing so, also highlights the benefits of developing new strategies to avoid silicide formation.

  5. Low-temperature FCC to L10 phase transformation in CoPt(Bi nanoparticles

    Directory of Open Access Journals (Sweden)

    Frank M. Abel

    2016-05-01

    Full Text Available This work is focused on the effects of Bi substitution on the synthesis of CoPt nanoparticles with the L10 structure using a modified organometallic approach. The structural and magnetic properties of the nanoparticles have been studied and compared directly with those of CoPt nanoparticles synthesized by the same technique but in the absence of Bi substitution. The as-synthesized particles at 330 °C have an average size of 11.7 nm and a partially ordered L10 phase with a coercivity of 1 kOe. The coercivity is increased to 9.3 kOe and 12.4 kOe after annealing for 1 hour at 600 and 700 °C. The structural and magnetic properties suggest that Bi promotes the formation of ordered L10 phase at low temperatures leading to the development of high coercivities.

  6. Fourth-order strain-gradient phase mixture model for nanocrystalline fcc materials

    Science.gov (United States)

    Klusemann, Benjamin; Bargmann, Swantje; Estrin, Yuri

    2016-12-01

    The proposed modeling approach for nanocrystalline materials is an extension of the local phase mixture model introduced by Kim et al (2000 Acta Mater. 48 493-504). Local models cannot account for any non-uniformities or strain patterns, i.e. such models describe the behavior correctly only as long as it is homogeneous. In order to capture heterogeneities, the phase mixture model is augmented with gradient terms of higher order, namely second and fourth order. Different deformation mechanisms are assumed to operate in grain interior and grain boundaries concurrently. The deformation mechanism in grain boundaries is associated with diffusional mass transport along the boundaries, while in the grain interior dislocation glide as well as diffusion controlled mechanisms are considered. In particular, the mechanical response of nanostructured polycrystals is investigated. The model is capable of correctly predicting the transition of flow stress from Hall-Petch behavior in conventional grain size range to an inverse Hall-Petch relation in the nanocrystalline grain size range. The consideration of second- and fourth-order strain gradients allows non-uniformities within the strain field to represent strain patterns in combination with a regularization effect. Details of the numerical implementation are provided.

  7. Simulation studies of three-phase differential protection of the converter transformer of FCC-HVDC%FCC-HVDC换流变压器三相差动保护仿真研究

    Institute of Scientific and Technical Information of China (English)

    许加柱; 白俊锋; 罗隆福; 李勇

    2011-01-01

    According to the specific wiring form of the converter transformer winding of FCC-HVDC, the action equations of three-phase protection and differential current expressions are deduced from its mathematical model. The transformer's three-phase protection model is established using Matlab/Simulink, and simulation results prove that the second order harmonic restraint principle may lead to delayed operation as internal fault of converter transformer occurs. Consequently, the simulation studies based on identification method of magnetic flux characteristics are carried out from the aspect of the action equations. The effectiveness of the proposed protection scheme in distinguishing the internal faults from the energizations of the converter transformer is validated.%根据FCC-HVDC系统中换流变压器绕组的具体接线形式,利用其数学模型推导三相保护的动作方程及差动电流表达式.用Matlab/Simulink建立变压器的三相保护模型,仿真结果验证了二次谐波制动原理在换流变压器内部故障时存在延时动作的可能.据此根据磁通特性原理鉴别法,从动作方程出发进行仿真分析,验证了该方法可以有效地区分换流变压器励磁涌流和故障电流.

  8. Phase field theory of interfaces and crystal nucleation in a eutectic system of fcc structure: I. Transitions in the one-phase liquid region.

    Science.gov (United States)

    Tóth, Gyula I; Gránásy, László

    2007-08-21

    The phase field theory (PFT) has been applied to predict equilibrium interfacial properties and nucleation barrier in the binary eutectic system Ag-Cu using double well and interpolation functions deduced from a Ginzburg-Landau expansion that considers fcc (face centered cubic) crystal symmetries. The temperature and composition dependent free energies of the liquid and solid phases are taken from CALculation of PHAse Diagrams-type calculations. The model parameters of PFT are fixed so as to recover an interface thickness of approximately 1 nm from molecular dynamics simulations and the interfacial free energies from the experimental dihedral angles available for the pure components. A nontrivial temperature and composition dependence for the equilibrium interfacial free energy is observed. Mapping the possible nucleation pathways, we find that the Ag and Cu rich critical fluctuations compete against each other in the neighborhood of the eutectic composition. The Tolman length is positive and shows a maximum as a function of undercooling. The PFT predictions for the critical undercooling are found to be consistent with experimental results. These results support the view that heterogeneous nucleation took place in the undercooling experiments available at present. We also present calculations using the classical droplet model [classical nucleation theory (CNT)] and a phenomenological diffuse interface theory (DIT). While the predictions of the CNT with a purely entropic interfacial free energy underestimate the critical undercooling, the DIT results appear to be in a reasonable agreement with the PFT predictions.

  9. Microemulsion-mediated synthesis of cobalt (pure fcc and hexagonal phases) and cobalt-nickel alloy nanoparticles.

    Science.gov (United States)

    Ahmed, Jahangeer; Sharma, Shudhanshu; Ramanujachary, Kandalam V; Lofland, Samuel E; Ganguli, Ashok K

    2009-08-15

    By choosing appropriate microemulsion systems, hexagonal cobalt (Co) and cobalt-nickel (1:1) alloy nanoparticles have been obtained with cetyltrimethylammonium bromide as a cationic surfactant at 500 degrees C. This method thus stabilizes the hcp cobalt even at sizes (fcc cobalt is predicted to be stable. On annealing the hcp cobalt nanoparticles in H(2) at 700 degrees C we could transform them to fcc cobalt nanoparticles. Microscopy studies show the formation of spherical nanoparticles of hexagonal and cubic forms of cobalt and Co-Ni (1:1) alloy nanoparticles with the average size of 4, 8 and 20 nm, respectively. Electrochemical studies show that the catalytic property towards oxygen evolution is dependent on the applied voltage. At low voltage (less than 0.65 V) the Co (hexagonal) nanoparticles are superior to the alloy (Co-Ni) nanoparticles while above this voltage the alloy nanoparticles are more efficient catalysts. The nanoparticles of cobalt (hcp and fcc) and alloy (Co-Ni) nanoparticles show ferromagnetism. The saturation magnetization of Co-Ni nanoparticles is reduced compared to the bulk possibly due to surface oxidation.

  10. Atomistic Simulation of Fcc-bcc Phase Transition in Single Crystal Al Under Uniform Deformation Compression%等变形压加载下单晶铝fcc-bcc相变的分子动力学模拟

    Institute of Scientific and Technical Information of China (English)

    郭钰; 何凯; 李莉; 梁九卿

    2012-01-01

    By molecular dynamics simulations employing an embedded atom method potential, we simulate structural transformations in single crystal Al caused by high rate uniform strain loading. The simulations show that the phase transition takes place at about 270 GPa, corresponding to the reduced volume of 0. 55V0,in reasonable agreement with the calculated value through density functional theory.%采用EAM势,利用分子动力学方法模拟了单晶铝在高速率等变形压加载条件下的fcc-bcc的结构相变.模拟结果表明,在等变形压加载条件下,单晶铝在加压至270 GPa左右,体积缩小至0.55V0时,由面心立方结构转变为体心立方结构.这一结果与第一原理计算的结果大致符合.

  11. FCC-ee Overview

    CERN Document Server

    Zimmermann, F; Benedikt, M; Burkhardt, H; Cerutti, F; Ferrari, A; Gutleber, J; Haerer, B; Holzer, B; Jensen, E; Kersevan, R; Lebrun, P; Martin, R; Mereghetti, A; Osborne, J; Papaphilippou, Y; Schulte, D; Tomas, R; Wenninger, J; Blondel, A; Koratzinos, M; Boscolo, M; Lari, L; Furukawa, K; Ohmi, K; Oide, K; White, S; Bogomyagkov, A; Koop, I; Levichev, E; Muchnoi, N; Nikitin, S; Shatilov, D; Wienands, U; Gianfelice, E; Medina, L

    2015-01-01

    The FCC-ee is a proposed circular e+e- collider installed in a new 100 km tunnel delivering high luminosity to four experiments at centre-of-mass energies ranging from 91 GeV (Z pole) over 160 GeV (W threshold) and 240 GeV (H production) to 350 GeV (t physics). The FCC-ee design is pursued as part of the global Future Circular Collider (FCC) study, which regards the FCC-ee as a potential intermediate step towards a 100-TeV hadron collider, called FCC-hh, sharing the same tunnel infrastructure. We here report the FCC-ee design status.

  12. Ion-irradiation-assisted phase selection in single crystalline Fe7Pd3 ferromagnetic shape memory alloy thin films: from fcc to bcc along the Nishiyama-Wassermann path.

    Science.gov (United States)

    Arabi-Hashemi, A; Mayr, S G

    2012-11-09

    When processing Fe-Pd ferromagnetic shape memory thin films, selection of the desired phases and their transformation temperatures constitutes one of the largest challenges from an application point of view. In the present contribution we demonstrate that irradiation with 1.8 MeV Kr(+) ions is the method of choice to achieve this goal: Single crystalline Fe(7)Pd(3) thin films that are grown with molecular beam epitaxy on MgO (001) substrates and subsequently irradiated with ions reveal a phase transformation along the whole phase transformation path ranging from fcc austenite to bcc martensite. While for 10(14) ions/cm(2) a fcc-fct phase transformation is observed, increasing the fluence to 5 × 10(14) ions/cm(2) and 5 × 10(15) ions/cm(2) leads to a phase transformation to the bcc phase. Pole figure measurements reveal an orientation relationship for the fcc-bcc phase transformation according to Nishiyama and Wassermann.

  13. Ferromagnetic properties of fcc Gd thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bertelli, T. P., E-mail: tambauh@gmail.com; Passamani, E. C.; Larica, C.; Nascimento, V. P.; Takeuchi, A. Y. [Universidade Federal do Espírito Santo, Departamento de Física, Vitória/ES 29075-910 (Brazil); Pessoa, M. S. [Universidade Federal do Espírito Santo, Departamento de Ciências Naturais, São Mateus/ES 29932-540 (Brazil)

    2015-05-28

    Magnetic properties of sputtered Gd thin films grown on Si (100) substrates kept at two different temperatures were investigated using X-ray diffraction, ac magnetic susceptibility, and dc magnetization measurements. The obtained Gd thin films have a mixture of hcp and fcc structures, but with their fractions depending on the substrate temperature T{sub S} and film thickness x. Gd fcc samples were obtained when T{sub S} = 763 K and x = 10 nm, while the hcp structure was stabilized for lower T{sub S} (300 K) and thicker film (20 nm). The fcc structure is formed on the Ta buffer layer, while the hcp phase grows on the fcc Gd layer as a consequence of the lattice relaxation process. Spin reorientation phenomenon, commonly found in bulk Gd species, was also observed in the hcp Gd thin film. This phenomenon is assumed to cause the magnetization anomalous increase observed below 50 K in stressed Gd films. Magnetic properties of fcc Gd thin films are: Curie temperature above 300 K, saturation magnetization value of about 175 emu/cm{sup 3}, and coercive field of about 100 Oe at 300 K; features that allow us to classify Gd thin films, with fcc structure, as a soft ferromagnetic material.

  14. Phase transition of 2×2 adsorbates on FCC(1 1 1) and HCP(0 0 0 1) surfaces

    Science.gov (United States)

    Sakamoto, Yoshifumi

    2003-04-01

    Order-disorder transition of adsorbates at metal surfaces is discussed based on Monte Carlo calculations for a lattice gas model on a triangular net. Repulsive interactions up to second neighbour sites and fixed concentration 1/4 of particles of lattice gas, are assumed for the 2×2 ordered structure. Calculated phase diagram and the critical exponent for susceptibility are presented. Stress is put on cases other than the second-order transition belonging to the four-state Potts universality class.

  15. High-temperature deformation of L12-FCC two-phase Ir-15Nb-Ni refractory superalloys

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The creep behaviors of the Ni-added Ir 85Nb15 alloys were investigated at 1 650~1 800 ℃ by compressi on tests in vacuum. X-ray diffractometry, transmission electron microscopy and scanning electron microscopy were conducted to characterize the microstructure and lattice misfit change by the addition of Ni in the Ir85Nb15 alloy. The results reveal that the Ni addition has a significant effect on the creep resistance of the Ir85Nb15 two-phase refractory superal loys. Basing on the results, the relationship among the Ni addition, lattice mis fit, microstructure development, and the creep behavior in the Ni-added Ir8 5Nb15 alloys is discussed.

  16. Luminosity Targets for FCC-hh

    CERN Document Server

    Zimmermann, F.; Buffat, X.; Schulte, D.

    2016-01-01

    We discuss the choice of target values for the peak and integrated luminosity of a future high-energy frontier circular hadron collider (FCC-hh). We review the arguments on the physics reach of a hadron collider. Next we show that accelerator constraints will limit the beam current and the turnaround time. Taking these limits into account, we derive an expression for the ultimate integrated luminosity per year, depending on a possible pile-up limit imposed by the physics experiments. We finally benchmark our result against the planned two phases of FCC-hh [1, 2, 3

  17. Temperature rise of installed FCC

    Science.gov (United States)

    Hankins, J. D.

    1976-01-01

    Report discusses temperature profiles of installed FCC for wood and tile surfaces. Three-conductor FCC was tested at twice nominal current-carrying capacity over bare floor and under carpet, with result indicating that temperature rise is not a linear function of current with FCC at this level.

  18. The FCC in Fiscal 1971.

    Science.gov (United States)

    Federal Communications Commission, Washington, DC.

    Fiscal 1971 saw major actions by the Federal Communications Commission (FCC) in all areas of its jurisdiction. In broadcasting, the FCC proposed new renewal rules and policies and issued a number of significant rulings on Fairness Doctrine matters. A policy statement outlining FCC cable television plans was submitted to the Congress. In the common…

  19. FCC Official Brochure - 2016

    CERN Multimedia

    Charitos, Panagiotis

    2016-01-01

    The FCC brochure describes the main scope of the study and give more information about the main scenarios explored under the study. It also highlights the R&D efforts under the study that will go into a Conceptual Design Report. Finally, it offers more information about the collaboration and a list of useful contact details.

  20. Fcc-bcc transition for Yukawa interactions determined by applied strain deformation

    OpenAIRE

    Hoy, Robert S.; Robbins, Mark O.

    2004-01-01

    Calculations of the work required to transform between bcc and fcc phases yield a high-precision bcc-fcc transition line for monodisperse point Yukawa (screened-Couloumb) systems. Our results agree qualitatively but not quantitatively with previously published simulations and phenomenological criteria for the bcc-fcc transition. In particular, the bcc-fcc-fluid triple point lies at a higher inverse screening length than previously reported.

  1. Ginzburg-Landau-type multiphase field model for competing fcc and bcc nucleation.

    Science.gov (United States)

    Tóth, G I; Morris, J R; Gránásy, L

    2011-01-28

    We address crystal nucleation and fcc-bcc phase selection in alloys using a multiphase field model that relies on Ginzburg-Landau free energies of the liquid-fcc, liquid-bcc, and fcc-bcc subsystems, and determine the properties of the nuclei as a function of composition, temperature, and structure. With a realistic choice for the free energy of the fcc-bcc interface, the model predicts well the fcc-bcc phase-selection boundary in the Fe-Ni system.

  2. Stability of the fcc structure in block copolymer systems.

    Science.gov (United States)

    Nonomura, Makiko

    2008-11-19

    The stability of the face-centered cubic (fcc) structure in microphase separated copolymers is investigated by a coarse-grained approach. Direct simulations of the equation for the microphase separation in three dimensions indicate that there is a narrow area above a certain degree of segregation in the phase diagram, where the fcc structure is the most stable structure. By employing the mode expansion, we have confirmed that the fcc structure can form as a metastable structure even in the weak segregation regime.

  3. The elastic properties and stability of fcc-Fe and fcc-FeNi alloys at inner-core conditions

    Science.gov (United States)

    Martorell, Benjamí; Brodholt, John; Wood, Ian G.; Vočadlo, Lidunka

    2015-07-01

    The agreement between shear wave velocities for the Earth's inner core observed from seismology with those derived from mineral physics is considerably worse than for any other region of the Earth. Furthermore, there is still debate as to the phase of iron present in the inner core, particularly when alloying with nickel and light elements is taken into account. To investigate the extent to which the mismatch between seismology and mineral physics is a function of either crystal structure and/or the amount of nickel present, we have used ab initio molecular dynamics simulations to calculate the elastic constants and seismic velocities (Vp and Vs) of face centred cubic (fcc) iron at Earth's inner core pressures (360 GPa) and at temperatures up to ˜7000 K. We find that Vp for fcc iron (fcc-Fe) is very similar to that for hexagonal close packed (hcp) iron at all temperatures. In contrast, Vs for fcc-Fe is significantly higher than in hcp-Fe, with the difference increasing with increasing temperature; the difference between Vs for the core (from seismology) and Vs for fcc-Fe exceeds 40 per cent. These results are consistent with previous work at lower temperatures. We have also investigated the effect of 6.5 and 13 atm% Ni in fcc-Fe. We find that Ni only slightly reduces Vp and Vs (e.g. by 2 per cent in Vs for 13 atm% Ni at 5500 K), and cannot account for the difference between the velocities observed in the core and those of pure fcc-Fe. We also tried to examine pre-melting behaviour in fcc-Fe, as reported in hcp-Fe by extending the study to very high temperatures (at which superheating may occur). However, we find that fcc-Fe spontaneously transforms to other hcp-like structures before melting; two hcp-like structures were found, both of hexagonal symmetry, which may most easily be regarded as being derived from an hcp crystal with stacking faults. That the structure did not transform to a true hcp phase is likely as a consequence of the limited size of the

  4. Phase transition from fcc to bcc structure of the Cu-clusters during nanocrystallization of Fe{sub 85.2}Si{sub 1}B{sub 9}P{sub 4}Cu{sub 0.8} soft magnetic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Nishijima, Masahiko; Matsuura, Makoto; Takenaka, Kana; Takeuchi, Akira; Makino, Akihiro [Research and Development Center for Ultra High Efficiency Nano-crystalline Soft Magnetic Material, Institute for Materials Research, Tohoku University, Sendai, Miyagi, 980 (Japan); Ofuchi, Hironori [Industrial Application Division, Japan Synchrotron Radiation Research Institute (JASRI) Kouto, Sayo, Hyogo 679-5198 (Japan)

    2014-05-15

    A role of Cu on the nanocrystallization of an Fe{sub 85.2}Si{sub 1}B{sub 9}P{sub 4}Cu{sub 0.8} alloy was investigated by X-ray absorption fine structure (XAFS) and transmission electron microscopy (TEM). The Cu K-edge XAFS results show that local structure around Cu is disordered for the as-quenched sample whereas it changes to fcc-like structure at 613 K. The fcc Cu-clusters are, however, thermodynamically unstable and begin to transform into bcc structure at 638 K. An explicit bcc structure is observed for the sample annealed at 693 K for 600 s in which TEM observation shows that precipitated bcc-Fe crystallites with ∼12 nm are homogeneously distributed. The bcc structure of the Cu-clusters transforms into the fcc-type again at 973 K, which can be explained by the TEM observations; Cu segregates at grain boundaries between bcc-Fe crystallites and Fe{sub 3}(B,P) compounds. Combining the XAFS results with the TEM observations, the structure transition of the Cu-clusters from fcc to bcc is highly correlated with the preliminary precipitation of the bcc-Fe which takes place prior to the onset of the first crystallization temperature, T{sub x1} = 707 K. Thermodynamic analysis suggests that an interfacial energy density γ between an fcc-Cu cluster and bcc-Fe matrix dominates at a certain case over the structural energy between fcc and bcc Cu, ΔG{sub fcc} {sub −} {sub bcc}, which causes phase transition of the Cu clusters from fcc to bcc structure.

  5. Neutron Scattering from fcc Pr and Pr3Tl

    DEFF Research Database (Denmark)

    Birgeneau, R. J.; Als-Nielsen, Jens Aage; Bucher, E.

    1972-01-01

    Elastic-neutron-scattering measurements on the singlet-ground-state ferromagnets fcc Pr and Pr3 Tl are reported. Both exhibit magnetic phase transitions, possibly to a simple ferromagnetic state at 20 and 11.6 °K, respectively. The transitions appear to be of second order although that in fcc Pr...... is clearly anomalous. Additional information on the inelastic scattering studies of the Γ1-Γ4 excitons in these systems is presented. dhcp Pr is also briefly discussed....

  6. The FCC: A Research Tool.

    Science.gov (United States)

    Wilson, Paul

    The numerous forms filed with the Federal Communications Commission (FCC) provide information about a variety of topics. Basic licensing information that is available concerns engineering, ownership, and equal employment opportunity. The FCC's broadcast bureau collects information about programing, the ascertainment of community needs, public…

  7. Synthesis of 4H/fcc-Au@Metal Sulfide Core-Shell Nanoribbons.

    Science.gov (United States)

    Fan, Zhanxi; Zhang, Xiao; Yang, Jian; Wu, Xue-Jun; Liu, Zhengdong; Huang, Wei; Zhang, Hua

    2015-09-02

    Although great advances on the synthesis of Au-semiconductor heteronanostructures have been achieved, the crystal structure of Au components is limited to the common face-centered cubic (fcc) phase. Herein, we report the synthesis of 4H/fcc-Au@Ag2S core-shell nanoribbon (NRB) heterostructures from the 4H/fcc Au@Ag NRBs via the sulfurization of Ag. Remarkably, the obtained 4H/fcc-Au@Ag2S NRBs can be further converted to a novel class of 4H/fcc-Au@metal sulfide core-shell NRB heterostructures, referred to as 4H/fcc-Au@MS (M = Cd, Pb or Zn), through the cation exchange. We believe that these novel 4H/fcc-Au@metal sulfide NRB heteronanostructures may show some promising applications in catalysis, surface enhanced Raman scattering, solar cells, photothermal therapy, etc.

  8. 47 CFR 2.926 - FCC identifier.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false FCC identifier. 2.926 Section 2.926... Authorizations § 2.926 FCC identifier. (a) A grant of equipment authorization issued by the Commission will list the validated FCC Identifier consisting of the grantee code assigned by the FCC pursuant to...

  9. Computer simulation of FCC riser reactors.

    Energy Technology Data Exchange (ETDEWEB)

    Chang, S. L.; Golchert, B.; Lottes, S. A.; Petrick, M.; Zhou, C. Q.

    1999-04-20

    A three-dimensional computational fluid dynamics (CFD) code, ICRKFLO, was developed to simulate the multiphase reacting flow system in a fluid catalytic cracking (FCC) riser reactor. The code solve flow properties based on fundamental conservation laws of mass, momentum, and energy for gas, liquid, and solid phases. Useful phenomenological models were developed to represent the controlling FCC processes, including droplet dispersion and evaporation, particle-solid interactions, and interfacial heat transfer between gas, droplets, and particles. Techniques were also developed to facilitate numerical calculations. These techniques include a hybrid flow-kinetic treatment to include detailed kinetic calculations, a time-integral approach to overcome numerical stiffness problems of chemical reactions, and a sectional coupling and blocked-cell technique for handling complex geometry. The copyrighted ICRKFLO software has been validated with experimental data from pilot- and commercial-scale FCC units. The code can be used to evaluate the impacts of design and operating conditions on the production of gasoline and other oil products.

  10. Virus-mediated FCC iron nanoparticle induced synthesis of uranium dioxide nanocrystals.

    Science.gov (United States)

    Ling, Tao; Yu, Huimin; Shen, Zhongyao; Wang, Hui; Zhu, Jing

    2008-03-19

    A reducing system involving M13 virus-mediated FCC Fe nanoparticles was employed to achieve uranium reduction and synthesize uranium dioxide nanocrystals. Here we show that metastable face-centered cubic (FCC) Fe nanoparticles were fabricated around the surface of the M13 virus during the specific adsorption of the virus towards Fe ions under a reduced environment. The FCC phase of these Fe nanoparticles was confirmed by careful TEM characterization. Moreover, this virus-mediated FCC Fe nanoparticle system successfully reduced contaminable U(VI) into UO(2) crystals with diameters of 2-5 nm by a green and convenient route.

  11. FCC 5 and FCC 6 (3/4)

    CERN Document Server

    CERN. Geneva; Schulte, Daniel

    2016-01-01

    Abstract: The electron-positron collider, FCC-ee, should provide collisions over a wide range of beam energies, ranging from roughly 35 GeV to almost 200 GeV. The physics goals of the FCC-ee collider call for luminosities around 1e36 cm-2s-1 per interaction point at the Z pole and several 1e34 cm-2s-1 at the ZH production peak. The beam energy should be pushed above 175 GeV, with a total synchrotron-radiation power not exceeding 100 MW. The extremely high luminosities and resulting short beam lifetime, due to radiative Bhabha scattering, can be sustained by top-up injection. The FCC-ee acce...

  12. Structural transformation between bcc and fcc in Fe-Ni nanoparticle during heating process

    Science.gov (United States)

    Li, Guojian; Sui, Xudong; Qin, Xuesi; Ma, Yonghui; Wang, Kai; Wang, Qiang

    2016-10-01

    Phase transformation between bcc and fcc in Fe-Ni nanoparticle has been studied by using molecular dynamics simulation with an embedded atom method. The transformation has been explored by designing the nanoparticles with different initial structures, sizes and elemental distributions at various Ni concentrations. The results show that the structural transformation is strongly related to the Ni content and elemental distribution. Initial fcc structure transforms to bcc for a lower Ni content and bcc transforms to fcc for a higher Ni content. The transformation is accompanied with a sharp reduction in energy even for the nanoparticle with a large size. Furthermore, lattice distortion first occurs before the transformation. The transformation from fcc to bcc is occurred by elongating fcc (100) to bcc (110) and that from bcc to fcc by compressing bcc (110) to fcc (100). The reason is that the nanoparticle has a low energy state for bcc structure with a lower Ni content and also for fcc structure with a higher Ni content. The coexistence of bcc and fcc phases appears with the change of elemental distribution.

  13. Lattice Dynamics of fcc Ca

    DEFF Research Database (Denmark)

    Stassis, C.; Zaretsky, J.; Misemer, D. K.;;

    1983-01-01

    to the propagation of elastic waves. The frequencies of the T1[ξξ0] branch for ξ between approximately 0.5 and 0.8 are slightly above the velocity-of-sound line determined from the low-frequency measurements. Since a similar effect has been observed in FCC Yb, it is natural to assume that the anomalous dispersion......A large single crystal of FCC Ca was grown and was used to study the lattice dynamics of this divalent metal by coherent inelastic neutron scattering. The phonon dispersion curves were measured, at room temperature, along the [ξ00], [ξξ0], [ξξξ], and [0ξ1] symmetry directions. The dispersion curves...... bear a striking resemblance to those of FCC Yb, which is also a divalent metal with an electronic band structure similar to that of Ca. In particular, the shear moduli c44 and (c11-c 12)/2 differ by a factor of 3.4, which implies that FCC Ca (like FCC Yb) is very anisotropic with regard...

  14. FCC-ee: Energy Calibration

    Energy Technology Data Exchange (ETDEWEB)

    Koratzinos, M. [Univ. of Geneva (Switzerland); Blondel, A. [Univ. of Geneva (Switzerland); Gianfelice-Wendt, E. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Zimmermann, F. [European Organization for Nuclear Research (CERN), Geneva (Switzerland)

    2015-06-02

    The FCC-ee aims to improve on electroweak precision measurements, with goals of 100 ke V on the Z mass and width, and a fraction of MeV on the W mass. Compared to LEP, this implies a much improved knowledge of the center-of-mass energy when operating at the Z peak and WW threshold. This can be achieved by making systematic use of resonant depolarization. A number of issues have been identified, due in particular to the long polarization times. However the smaller emittance and energy spread of FCC-ee with respect to LEP should help achieve a much improved performance.

  15. FCC-ee: Energy calibration

    CERN Document Server

    Koratzinos, M; Gianfelice-Wendt, E; Zimmermann, F

    2015-01-01

    The FCC-ee aims to improve on electroweak precision measurements, with goals of 100 keV on the Z mass and width, and a fraction of MeV on the W mass. Compared to LEP, this implies a much improved knowledge of the centre-of-mass energy when operating at the Z peak and WW threshold. This can be achieved by making systematic use of resonant depolarization. A number of issues have been identified, due in particular to the long polarization times. However the smaller emittance and energy spread of FCC-ee with respect to LEP should help achieve a much improved performance.

  16. New developments in FCC catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Kelkar, C.P. [BASF Corporation, Iselin, NJ (United States)

    2011-07-01

    Fluid catalytic cracking (FCC) unit is one of the primary boiling point reduction units in the refinery that converts longer chain crude oil to useful products such as distillate, gasoline and LPG. As the quality of feedstock deteriorates, while specifications on the product side are becoming more and more stringent, the FCC unit is being severely challenged. Over the past few years BASF has introduced two new platform technologies that will assist in this challenge. This paper will present an overview of those platforms and also provide a brief update on the research underway to mitigate the current REO crisis. (orig.)

  17. FCC 3 and FCC 4 (2/4)

    CERN Document Server

    CERN. Geneva; Dam, Mogens

    2016-01-01

    Abstract: Owing to its specific interaction region design, the FCC-ee will be able to deliver unprecedented luminosities at centre-of-mass energies ranging from below the Z pole to the ttbar threshold and above. Operation at four energy regimes - at the Z pole, at the WW threshold, at 240 GeV for Higgs production, and at the ttbar thre...

  18. FCC and the Sunshine Act.

    Science.gov (United States)

    Weiss, Kenneth

    The Sunshine Act, designed to encourage open meetings to increase public understanding of the governmental decision-making process, went into effect in March 1977. A total of 50 agencies, including the Federal Communications Commission (FCC), are subject to the provisions of the Sunshine Act. The act lists 10 exemptions, any of which can result in…

  19. Radiation damage in fcc metals

    NARCIS (Netherlands)

    Lindgreen, Ronald Julius Theodorus

    1984-01-01

    In dit proefschrift worden de structuurveranderingen ten gevolge van stralingsschade behandeld, in het bijzonder schade ontstaan door implantatie van zware deeltjes in fcc metalen. Gedetailleerde kennis van deze structuurveranderingen is van belang gezien de grote en soms gunstige invloed hiervan op

  20. Phase field theory of interfaces and crystal nucleation in a eutectic system of fcc structure: II. Nucleation in the metastable liquid immiscibility region.

    Science.gov (United States)

    Tóth, Gyula I; Gránásy, László

    2007-08-21

    In the second part of our paper, we address crystal nucleation in the metastable liquid miscibility region of eutectic systems that is always present, though experimentally often inaccessible. While this situation resembles the one seen in single component crystal nucleation in the presence of a metastable vapor-liquid critical point addressed in previous works, it is more complex because of the fact that here two crystal phases of significantly different compositions may nucleate. Accordingly, at a fixed temperature below the critical point, six different types of nuclei may form: two liquid-liquid nuclei: two solid-liquid nuclei; and two types of composite nuclei, in which the crystalline core has a liquid "skirt," whose composition falls in between the compositions of the solid and the initial liquid phases, in addition to nuclei with concentric alternating composition shells of prohibitively high free energy. We discuss crystalline phase selection via exploring/identifying the possible pathways for crystal nucleation.

  1. THE DEVELOPMENT OF FCC STRIPPING TECHNOLOGY

    Institute of Scientific and Technical Information of China (English)

    ZHANGZhen-qian

    2003-01-01

    This article briefly describes the major patents domestic and the abroad,and the current situation and achievements of FCC stripping technology in China.The develping trend of FCC stripping technology is presented,including further developments of FCC stripper to improve unit performance,combination of the stripper and pre-stripper within disengager to from a complete high-efficiency FCC stripping system.In addition to high efficiency,simple structure and easiness of installation and maintenance for a new FCC stripper are all of consideration.

  2. Ab initio lattice stability of fcc and hcp Fe-Mn random alloys.

    Science.gov (United States)

    Gebhardt, T; Music, D; Hallstedt, B; Ekholm, M; Abrikosov, I A; Vitos, L; Schneider, J M

    2010-07-28

    We have studied the lattice stability of face centred cubic (fcc) versus hexagonal close packed (hcp) Fe-Mn random alloys using ab initio calculations. In the calculations we considered the antiferromagnetic order of local moments, which for fcc alloys models the magnetic configuration of this phase at room temperature (below its Néel temperature) as well as their complete disorder, corresponding to paramagnetic fcc and hcp alloys. For both cases, the results are consistent with our thermodynamic calculations, obtained within the Calphad approach. For the room temperature magnetic configuration, the cross-over of the total energies of the hcp phase and the fcc phase of Fe-Mn alloys is at the expected Mn content, whereas for the magnetic configuration above the fcc Néel temperature, the hcp lattice is more stable within the whole composition range studied. The increase of the total energy difference between hcp and antiferromagnetic fcc due to additions of Mn as well as the stabilizing effect of antiferromagnetic ordering on the fcc phase are well displayed. These results are of relevance for understanding the deformation mechanisms of these random alloys.

  3. Antiferromagnetic resonance in the Mott insulator fcc-Cs3C60.

    Science.gov (United States)

    Suzuki, Yuta; Shibasaki, Seiji; Kubozono, Yoshihiro; Kambe, Takashi

    2013-09-11

    The magnetic ground state of the fcc phase of the Mott insulator Cs3C60 was studied using a low-temperature electron spin resonance technique, and antiferromagnetic resonance (AFMR) below 1.57 K was directly observed at ambient pressure. The AFMR modes for the fcc phase of Cs3C60 were investigated using a conventional two-sublattice model with uniaxial anisotropy, and the spin-flop field was determined to be 4.7 kOe at 1.57 K. The static magnetic exchange interactions and anisotropy field for fcc-Cs3C60 were also estimated.

  4. Role of five-fold twin boundary on the enhanced mechanical properties of fcc Fe nanowires.

    Science.gov (United States)

    Wu, J Y; Nagao, S; He, J Y; Zhang, Z L

    2011-12-14

    The role of 5-fold twin boundary on the structural and mechanical properties of fcc Fe nanowire under tension is explored by classical molecular dynamics. Twin-stabilized fcc nanowire with various diameters (6-24 nm) are examined by tension tests at several temperatures ranging from 0.01 to 1100 K. Significant increase in the Young's modulus of the smaller nanowires is revealed to originate from the central area of quinquefoliolate-like stress-distribution over the 5-fold twin, rather than from the surface tension that is often considered as the main source of such size-effects found in nanostructures. Because of the excess compressive stress caused by crossing twin-boundaries, the atoms in the center behave stiffer than those in bulk and even expand laterally under axial tension, providing locally negative Poisson's ratio. The yield strength of nanowire is also enhanced by the twin boundary that suppresses dislocation nucleation within a fcc twin-domain; therefore, the plasticity of nanowire is initiated by strain-induced fcc→bcc phase transformation that destroys the twin structure. After the yield, the nucleated bcc phase immediately spreads to the entire area, and forms a multigrain structure to realize ductile deformation followed by necking. As temperature elevated close to the critical temperature between bcc and fcc phases, the increased stability of fcc phase competes with the phase transformation under tension, and hence dislocation nucleations in fcc phase are observed exclusively at the highest temperature in our study.

  5. Phase transition from fcc to bcc structure of the Cu-clusters during nanocrystallization of Fe85.2Si1B9P4Cu0.8 soft magnetic alloy

    OpenAIRE

    Masahiko Nishijima; Makoto Matsuura; Kana Takenaka; Akira Takeuchi; Hironori Ofuchi; Akihiro Makino

    2014-01-01

    A role of Cu on the nanocrystallization of an Fe85.2Si1B9P4Cu0.8 alloy was investigated by X-ray absorption fine structure (XAFS) and transmission electron microscopy (TEM). The Cu K-edge XAFS results show that local structure around Cu is disordered for the as-quenched sample whereas it changes to fcc-like structure at 613 K. The fcc Cu-clusters are, however, thermodynamically unstable and begin to transform into bcc structure at 638 K. An explicit bcc structure is observed for the sample an...

  6. QCD and $\\gamma\\,\\gamma$ studies at FCC-ee

    CERN Document Server

    Skands, Peter

    2016-01-01

    The Future Circular Collider (FCC) is a post-LHC project aiming at searches for physics beyond the SM in a new 80--100~km tunnel at CERN. Running in its first phase as a very-high-luminosity electron-positron collider (FCC-ee), it will provide unique possibilities for indirect searches of new phenomena through high-precision tests of the SM. In addition, by collecting tens of ab$^{-1}$ integrated luminosity in the range of center-of-mass energies $\\sqrt{s}$~=90--350~GeV, the FCC-ee also offers unique physics opportunities for precise measurements of QCD phenomena and of photon-photon collisions through, literally, billions of hadronic final states as well as unprecedented large fluxes of quasireal $\\gamma$'s radiated from the $\\rm e^+e^-$ beams. We succinctly summarize the FCC-ee perspectives for high-precision extractions of the QCD coupling, for detailed analyses of parton radiation and fragmentation, and for SM and BSM studies through $\\gamma\\gamma$ collisions.

  7. Effect of hydrotreating FCC feedstock on product distribution

    Energy Technology Data Exchange (ETDEWEB)

    Salazar-Sotelo, D.; Maya-Yescas, R.; Mariaca-Dominguez, E.; Rodriguez-Salomon, S.; Aguilera-Lopez, M. [Programa de Tratamiento de Crudo Maya, Instituto Mexicano del Petroleo, Lazaro Cardenas 152, San Bartolo Atepehuacan, 07730 Mexico, D.F. (Mexico)

    2004-11-24

    The demand of low-sulfur fuels has been increasing during the last 20 years due to environmental concerns about SO{sub x} emissions from processing plants and engines. Due to its high contribution to the gasoline pool, hydrotreating fluid catalytic cracking (FCC) feedstock offers several advantages, such as the increase of conversion and yields of gasoline and liquid-phase gas, meanwhile sulfur content in fuels is diminished. However, there are more important factors to be considered when hydrotreating FCC feedstock.In this work, two FCC feedstocks, typical and hydrotreated, were converted in a microactivity test (MAT) reactor, as described by ASTM D-3907-92, at different severities and using two commercial catalysts. Feedstock conversion, product yields and selectivity to valuable products were compared against industrial-scale results predicted by using commercial FCC simulation software. Expected increment in conversion and yield to profitable products was observed when hydrotreated feedstock was used; simulation results follow acceptably MAT results. Some recommendations are given for looking closely at the overall behavior (riser-regenerator), using reliable kinetic models and simulation programs.

  8. 47 CFR 73.878 - Station inspections by FCC; availability to FCC of station logs and records.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Station inspections by FCC; availability to FCC... (LPFM) § 73.878 Station inspections by FCC; availability to FCC of station logs and records. (a) The... FCC during the station's business hours, and at any time it is in operation. In the course of...

  9. The FCC and the Electric Church.

    Science.gov (United States)

    Abrams, Michael F.

    This newsletter focuses on the relationship between the Federal Communications Commission (FCC) and religious broadcasters. It traces the history of that relationship and discusses some of the pressures put on both. It includes a discussion of a recent avalanche of mail at the FCC supporting the church on the airways. It also summarizes some of…

  10. 47 CFR 2.936 - FCC inspection.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false FCC inspection. 2.936 Section 2.936 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL... Authorization § 2.936 FCC inspection. Upon reasonable request, each responsible party shall submit the...

  11. Epitaxial Growth of Metastable hcp-Ni and hcp-NiFe Thin Films on Au(100)fcc Single-Crystal Underlayers and Their Structure Characterization

    Science.gov (United States)

    Ohtake, Mitsuru; Sato, Yoichi; Higuchi, Jumpei; Tanaka, Takahiro; Kirino, Fumiyoshi; Futamoto, Masaaki

    2011-10-01

    Metastable hcp-Ni and hcp-NiFe epitaxial thin films are prepared on Au(100)fcc single-crystal underlayers by molecular beam epitaxy. The epitaxial growth and the transformation from metastable hcp to more stable fcc phase are studied by in-situ reflection high-energy electron diffraction. In an early stage of film growth, hcp(1120) crystal is stabilized through hetero-epitaxial growth. The epitaxial orientation relationship between the film and the underlayer is determined to be hcp(1120)[0001], hcp(1120)[1100] ∥ Au(100)[001]fcc. With increasing the film thickness, the hcp structure starts to transform into fcc structure. High-resolution transmission electron microscopy shows that the film consists of a mixture of hcp and fcc crystals and that a large number of stacking faults exist parallel to the close-packed plane. The results suggest that the hcp structure starts to transform from these stacking faults into fcc structure in the lateral direction by atomic displacement parallel to the hcp(0001) close-packed plane. The crystallographic orientation relationships between the hcp and transformed fcc crystals are determined to be fcc(110)[111], fcc(110)[111] ∥ hcp(1120)[0001] and fcc(110)[112], fcc(110)[112] ∥ hcp(1120)[1100].

  12. DETERMINATION OF IDEAL PARTITIONING-RATIOS AND-PARAMETERS OF SUBSTITUTIONAL ELEMENTS AND LATTICE CELL NUMBER OF TWO-PHASE ALLOYS WITH FCC,BCC AND HCP STRUCTURES%FCC,BCC和HCP结构两相合金中置换型元素理想分配比和分配系数及晶胞比的确定

    Institute of Scientific and Technical Information of China (English)

    彭志方; 任遥遥

    2001-01-01

    从原子分数及晶胞原子数的角度导出FCC,BCC及HCP结构两相合金中元素分配比和分配系数.通过对上述3种典型合金相结构的9种组合计算发现,任意两相之间存在一致的元素分配比和元素分配系数;两相各自的晶胞数及其比值与合金及其组成相成分之间存在特征关系;采用合金元素分配系数法算得的合金相成分与其观测值或采用统计回归法算得的相应值吻合程度较好.

  13. Magnetism in bcc and fcc Fe with carbon and manganese.

    Science.gov (United States)

    Medvedeva, N I; Van Aken, D; Medvedeva, J E

    2010-08-11

    Density functional theory calculations were performed to study the structure and magnetic properties of bcc (α) and fcc (γ) Fe with 3 at.% carbon and manganese impurities. We find that all bcc-based Fe, Fe-C and Fe-Mn-C phases exhibit a ferromagnetic (FM) ground state, while the antiferromagnetic double-layer (AFMD) state is lowest in energy within the collinear spin approach in fcc Fe, Fe-C and Fe-Mn-C phases. However, the carbon and manganese impurities affect the local magnetic interactions significantly. The states with opposite manganese magnetic moments are quasi-degenerate in bcc Fe-Mn alloy, whereas octa-site carbon stabilizes ferromagnetic coupling of the nearest manganese atom with the Fe host. We demonstrate that the antiferromagnetic (AFM) fcc Fe-C and Fe-Mn-C alloys are intrinsically inhomogeneous magnetic systems. Carbon frustrates the local magnetic order by reorientation of magnetic moments of the nearest Mn and Fe atoms, and favors their ferromagnetic coupling. The competition between ferromagnetic and antiferromagnetic Fe-Fe and Fe-Mn interactions and the local magnetovolume instability near carbon may give rise to the spin-glass-like regions observed in austenitic Fe-Mn-C alloys.

  14. Magnetism in bcc and fcc Fe with carbon and manganese

    Energy Technology Data Exchange (ETDEWEB)

    Medvedeva, N I [Institute of Solid State Chemistry, Yekaterinburg 620990 (Russian Federation); Van Aken, D [Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409 (United States); Medvedeva, J E [Department of Physics, Missouri University of Science and Technology, Rolla, MO 65409 (United States)

    2010-08-11

    Density functional theory calculations were performed to study the structure and magnetic properties of bcc ({alpha}) and fcc ({gamma}) Fe with 3 at.% carbon and manganese impurities. We find that all bcc-based Fe, Fe-C and Fe-Mn-C phases exhibit a ferromagnetic (FM) ground state, while the antiferromagnetic double-layer (AFMD) state is lowest in energy within the collinear spin approach in fcc Fe, Fe-C and Fe-Mn-C phases. However, the carbon and manganese impurities affect the local magnetic interactions significantly. The states with opposite manganese magnetic moments are quasi-degenerate in bcc Fe-Mn alloy, whereas octa-site carbon stabilizes ferromagnetic coupling of the nearest manganese atom with the Fe host. We demonstrate that the antiferromagnetic (AFM) fcc Fe-C and Fe-Mn-C alloys are intrinsically inhomogeneous magnetic systems. Carbon frustrates the local magnetic order by reorientation of magnetic moments of the nearest Mn and Fe atoms, and favors their ferromagnetic coupling. The competition between ferromagnetic and antiferromagnetic Fe-Fe and Fe-Mn interactions and the local magnetovolume instability near carbon may give rise to the spin-glass-like regions observed in austenitic Fe-Mn-C alloys.

  15. Martensitic transformation fcc(γ)→hcp(ε)

    Institute of Scientific and Technical Information of China (English)

    徐祖耀

    1997-01-01

    Criteria of the thermoelastic martensitic transformation are suggested, on the basis of which the martensitic transformation fcc(γ)→hcp(ε) in Fe-Mn-Si based alloys is classified as a semi-thermoelastic transformation In contrast with the martensitic transformation fcc(γ)→bct(bcc)α’ in iron-based alloys, the thermoelastic transformation in Cu-based alloys and the t→m transformation in ceramics containing ZrO2, in γ→ε of Fe-Mn-Si, the strengthening and grain size of the parent phase will not markedly affecl the Ms and the internal friction peak indicating the martensitic Transformation does not correspond to a significant lowering of the elastic modulus, implying that the nucleation of ε-martensite may occur directly through the stacking fault and may not strongly depend on soft mode. A comparison between the thermal and stress induced ε martensites is made and a brief discussion is given.

  16. Study on Commercial Application of FCC with Auxiliary Gasoline Reactor for Improving FCC Naphtha Quality

    Institute of Scientific and Technical Information of China (English)

    Wei Qiang

    2007-01-01

    This article introduces the commercial application of FCC technology equipped with a gasoline auxiliary reactor in the RFCC unit at PetroChina Harbin Petrochemical Branch Company.Test results have shown the excellent outcome for commercial application of the gasoline upgrading in the auxiliary reactor to reduce the olefin content in FCC naphtha.Application of this technology can reduce the olefin content in FCC naphtha to less than 35v%.Adjustment of the FCC operation towards more severg conditions can further reduce the olefin content in FCC naphtha to less than 20 v%.so that the FCC naphtha can meet the current standard or meet more stringent specification requirements in the future to achieve compelling economic and social benefits.

  17. 47 CFR 1.8001 - FCC Registration Number (FRN).

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false FCC Registration Number (FRN). 1.8001 Section 1.8001 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE FCC Registration Number § 1.8001 FCC Registration Number (FRN). (a) The FCC Registration Number (FRN) is a...

  18. 47 CFR 80.417 - FCC Rules and Regulations.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false FCC Rules and Regulations. 80.417 Section 80... STATIONS IN THE MARITIME SERVICES Station Documents § 80.417 FCC Rules and Regulations. The Commission's... available on the Commission's web site at www.fcc.gov or ftp.fcc.gov....

  19. Discussions on the Feasibility of Using FCC Offgas for Atomization of FCC Feed

    Institute of Scientific and Technical Information of China (English)

    Cao Dongxue

    2005-01-01

    The consumption of steam as a traditional means for feedstock atomization accounts for a relatively large share in the process energy use and makes up the main part of sulfur containing wastewater. This article on the basis of comprehensive analysis puts forward a proposition on using the FCC offgas as the medium for atomizing the FCC feed, which would play a realistic role for energy conservation and environmental protection of FCC process.

  20. Military and aerospace applications of FCC

    Science.gov (United States)

    Swanson, C.

    1972-01-01

    Military and NASA programs are discussed in which FCC were used. Included are Saturn 4, Pegasus satellites solar, array for Skylab orbital workshop, Poseidon missiles, MK 48 torpedo fire control, and Lunar Surveyor.

  1. Beam dynamics issues in the FCC

    CERN Document Server

    AUTHOR|(CDS)2067437; Benedikt, Michael; Besana, Maria Ilaria; Bruce, Roderik; Bruning, Oliver; Buffat, Xavier; Burkart, Florian; Burkhardt, Helmut; Calatroni, Sergio; Cerutti, Francesco; Fartoukh, Stephane; Fiascaris, Maria; Garion, Cedric; Goddard, Brennan; Hofle, Wolfgang; Holzer, Bernhard; Jowett, John; Kersevan, Roberto; Martin, Roman; Mether, Lotta Maria; Milanese, Attilio; Pieloni, Tatiana; Redaelli, Stefano; Rumolo, Giovanni; Salvant, Benoit; Schaumann, Michaela; Schulte, Daniel; Chapochnikova, Elena; Stoel, Linda; Tambasco, Claudia; Tomas Garcia, Rogelio; Tommasini, Davide; Zimmermann, Frank; Guillermo Canton, Gerardo; Kornilov, Vladimir; Boine-Frankenheim, Oliver; Niedermayer, Uwe; Mitsuhashi, Toshiyuki; Ohmi, Kazuhito; Chance, Antoine; Dalena, Barbara; Payet, Jacques; Bambade, Philip; Faus-Golfe, Angeles; Molson, James; Biarrotte, Jean-Luc; Lachaize, Antoine; Fox, John D; Stupakov, Gennady; Abelleira, Jose; Cruz Alaniz, Emilia; Seryi, Andrei; Appleby, Robert Barrie; Boscolo, Manuela; Collamati, Francesco; Drago, Alessandro; Barranco Garcia, Javier; Khan, Shaukat; Riemann, Bernhard

    2016-01-01

    The international Future Circular Collider (FCC) study is designing hadron, lepton and lepton-hadron colliders based on a new 100 km tunnel in the Geneva region. The main focus and ultimate goal of the study are high luminosity proton-proton collisions at a centre-of-mass energy of 100 TeV, using 16 T Nb3Sn dipole magnets. Specific FCC beam dynamics issues are related to the large circumference, the high brightness—made available by radiation damping —, the small geometric emittance, unprecedented collision energy and luminosity, the huge amount of energy stored in the beam, large synchrotron radiation power, plus the injection scenarios. In addition to the FCC-hh proper, also a High-Energy LHC (HE-LHC) is being explored, using the FCC-hh magnet technology in the existing LHC tunnel, which can yield a centre-of-mass energy around 25 TeV.

  2. The hcp to fcc transformation path of scandium trihydride under high pressure.

    Science.gov (United States)

    Pakornchote, T; Pinsook, U; Bovornratanaraks, T

    2014-01-15

    We used density functional theory to calculate the phase stability of the hcp (hexagonal close packed) and the fcc (face centered cubic) structures of ScH3. The hcp form is stable up to 22 GPa according to the generalized gradient approximation calculation. Then the fcc form becomes energetically more stable. In order to provide insight into the phase transition mechanism, we modeled the hcp to fcc transition by sliding the hcp basal planes, i.e. (001)h planes, in such a way that the ABABAB sequence of the hcp form is altered into the ABCABC sequence of the fcc form. This sliding was suggested by the experiment. The configurations of these sliding steps are our proposed intermediate configurations, whose symmetry group is the Cm group. By using the Cm crystallography, we can match the d-spacings from the lattice planes of the hcp and fcc forms and the intermediate planes measured from the experiment. We also calculated the enthalpy per step, from which the energy barrier between the two phases at various pressures was derived. The barrier at 35 GPa is 0.370 eV per formula or 0.093 eV/atom. The movements of the hydrogen atoms during the hcp to intermediate phase transition are consistent with the result from the Raman spectra.

  3. 78 FR 66357 - Proposed Changes to FCC Form 499-A, FCC Form 499-Q, and Accompanying Instructions

    Science.gov (United States)

    2013-11-05

    ... COMMISSION Proposed Changes to FCC Form 499-A, FCC Form 499-Q, and Accompanying Instructions AGENCY: Federal... annual Telecommunications Reporting Worksheet, FCC Form 499-A (Form 499-A) and accompanying instructions... Telecommunications Reporting Worksheet, FCC Form 499-Q (Form 499-Q) and accompanying instructions (Form...

  4. 78 FR 69415 - Proposed Changes to FCC Form 499-A, FCC Form 499-Q, and Accompanying Instructions.

    Science.gov (United States)

    2013-11-19

    ... COMMISSION Proposed Changes to FCC Form 499-A, FCC Form 499-Q, and Accompanying Instructions. AGENCY: Federal... to (1) the annual Telecommunications Reporting Worksheet, FCC Form 499-A (Form 499-A) and... quarterly Telecommunications Reporting Worksheet, FCC Form 499-Q (Form 499-Q) and accompanying...

  5. Synthesis of 4H/fcc Noble Multimetallic Nanoribbons for Electrocatalytic Hydrogen Evolution Reaction.

    Science.gov (United States)

    Fan, Zhanxi; Luo, Zhimin; Huang, Xiao; Li, Bing; Chen, Ye; Wang, Jie; Hu, Yanling; Zhang, Hua

    2016-02-03

    Noble multimetallic nanomaterials, if only consisting of Au, Ag, Pt, and Pd, typically adopt the high-symmetry face-centered cubic (fcc) structure. Here for the first time, by using the 4H/fcc Au@Ag nanoribbons (NRBs) as seeds, we report the synthesis of 4H/fcc trimetallic Au@PdAg core-shell NRBs via the galvanic reaction method under ambient conditions. Moreover, this strategy can also be used to synthesize 4H/fcc trimetallic Au@PtAg and quatermetallic Au@PtPdAg core-shell NRBs. Impressively, for the first time, these alloy shells, i.e., PdAg, PtAg, and PtPdAg, epitaxially grown on the 4H/fcc Au core with novel 4H hexagonal phase were successfully synthesized. Remarkably, the obtained 4H/fcc Au@PdAg NRBs exhibit excellent electrocatalytic activity toward the hydrogen evolution reaction, which is even quite close to that of the commercial Pt black. We believe that our findings here may provide a novel strategy for the crystal-structure-controlled synthesis of advanced functional noble multimetallic nanomaterials with various promising applications.

  6. Theoretical and experimental study of metastable solid solutions and phase stability within the immiscible Ag-Mo binary system

    Science.gov (United States)

    Sarakinos, K.; Greczynski, G.; Elofsson, V.; Magnfält, D.; Högberg, H.; Alling, B.

    2016-03-01

    Metastable solid solutions are phases that are synthesized far from thermodynamic equilibrium and offer a versatile route to design materials with tailor-made functionalities. One of the most investigated classes of metastable solid solutions with widespread technological implications is vapor deposited ternary transition metal ceramic thin films (i.e., nitrides, carbides, and borides). The vapor-based synthesis of these ceramic phases involves complex and difficult to control chemical interactions of the vapor species with the growing film surface, which often makes the fundamental understanding of the composition-properties relations a challenging task. Hence, in the present study, we investigate the phase stability within an immiscible binary thin film system that offers a simpler synthesis chemistry, i.e., the Ag-Mo system. We employ magnetron co-sputtering to grow Ag1-xMox thin films over the entire composition range along with x-ray probes to investigate the films structure and bonding properties. Concurrently, we use density functional theory calculations to predict phase stability and determine the effect of chemical composition on the lattice volume and the electronic properties of Ag-Mo solid solutions. Our combined theoretical and experimental data show that Mo-rich films (x ≥ ˜0.54) form bcc Mo-Ag metastable solid solutions. Furthermore, for Ag-rich compositions (x ≤ ˜0.21), our data can be interpreted as Mo not being dissolved in the Ag fcc lattice. All in all, our data show an asymmetry with regards to the mutual solubility of Ag and Mo in the two crystal structures, i.e., Ag has a larger propensity for dissolving in the bcc-Mo lattice as compared to Mo in the fcc-Ag lattice. We explain these findings in light of isostructural short-range clustering that induces energy difference between the two (fcc and bcc) metastable phases. We also suggest that the phase stability can be explained by the larger atomic mobility of Ag atoms as compared to that

  7. Appropriate deposition parameters for formation of fcc Co-Ni alloy nanowires during electrochemical deposition process

    Science.gov (United States)

    Mukhtar, Aiman; Shahzad Khan, Babar; Mehmood, Tahir

    2016-12-01

    The effect of deposition potential on the crystal structure and composition of Co-Ni alloy nanowires is studied by XRD, FE-SEM and EDX. The alloy nanowires deposited at -3.2 V are metastable fcc phase Co-Ni. The alloy nanowires deposited at -1.8 V are hcp phase Co-Ni. The formation of the metastable fcc alloy nanowires can be attributed to smaller critical clusters formed at the high potential as the smaller critical clusters favor fcc structure because of the significant surface energy effect. The content of Co inside nanowires increases with increasing potential. This can be understood by the polarization curves of depositing Co and Ni nanowires, which show that the current density ratio of Ni to Co at low potential has larger value than that at high potential.

  8. Photocatalytic Denitrogenation over Modiifed Waste FCC Catalyst

    Institute of Scientific and Technical Information of China (English)

    Zheng Liuping; Lin Mei; Huang Yingying; Yan Guiyang; Zheng Binquan; Li Ling

    2013-01-01

    The strontium modiifed waste FCC catalyst was prepared by magnetic stirring method and characterized by X-ray diffractometry (XRD), UV-Vis diffuse relfectance spectrometry (DRS), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Meanwhile, its photocatalytic denitrogenation performance was evaluated in terms of its ability to degrade the N-containing simulation oil under visible light. A mixture of strontium nitrate solution (with a concentration of 0.5 mol/L) and waste FCC catalyst was calcined at 400℃for 5 h prior to taking part in the photocatalytic denitrogenation reaction. The test results showed that the photocatalytic degradation rate of pyridine contained in simulation oil in the presence of the strontium modiifed FCC catalyst could reach 92.0%under visible light irradiation for 2.5 h.

  9. Status and Challenges for FCC-ee

    CERN Document Server

    Benedikt, Michael; Zimmermann, Frank; Bogomyagkov, Anton; Levichev, Eugene; Migliorati, Mauro; Wienands, Uli

    2015-01-01

    We report the design status and beam dynamics challenges for the electron-positron branch of the Future Circular Collider (FCC) study, as of August 2015. After recalling motivation and physics requirements for the FCC-ee, we briefly discuss configurations and parameters, collider layout, the superconducting RF system, possible staging scenarios, final-focus optics, interaction-region (IR) issues, machine detector interface and IR synchrotron radiation, dynamic aperture, beam-beam effects, top-up injection, mono-chromatization option, impedances, instabilities, energy calibration and polarization, and SuperKEKB as a key demonstrator, before presenting conclusions and outlook.

  10. FCC Fe2NiSi prepared by mechanical alloying and stabilization effect of L21B disorder on BCC Heusler structure

    Science.gov (United States)

    Luo, Hongzhi; Xin, Yuepeng; Ma, Yuexing; Liu, Bohua; Meng, Fanbin; Liu, Heyan; Liu, Enke; Wu, Guangheng

    2016-12-01

    Fe2NiSi FCC phase has been prepared by ball-milling successfully, which is different from the BCC Heusler phase prepared by arc-melting in previous literatures. The FCC Fe2NiSi is a ferromagnet with a lattice constant of 3.58 Å. The phase stability of the FCC and BCC Fe2NiSi has been compared by first-principles calculations. It has been found that the FCC structure has a lower total energy compared with the highly-ordered Heusler structures XA and L21, that is the reason why the FCC phase can be prepared by ball-milling. However, the Fe (A)-Ni (C) disorder in the BCC XA structure can lower its total energy further and make it smaller than the FCC phase. So the most stable structure in Fe2NiSi is L21B, as has been observed in the arc-melting sample. This can be explained from their DOS structures. The calculated total moments for the FCC and BCC phases agree with their Ms at 5 K quite well.

  11. Stacking fault energy in FCC plutonium with multiple reference states in the modified embedded atom method

    Science.gov (United States)

    Valone, S. M.; Baskes, M. I.; Rudin, S. P.

    2012-03-01

    Basic concepts from the multi-reference state formalism for determining the functions for the modified embedded atom method (MEAM) are adopted to modeling elemental plutonium (Pu). In the case of elemental Pu, the focus is on the background electron density. Here we utilize a portion of the formalism that determines the structure of the background density necessary to capture correct phase ordering between fcc and ideal hcp crystal structures. The critical information comes from cold curves, that is the energy/volume relationships, for these phases. Practically speaking, the energy difference between these two phases determines the stacking fault energy of the material. At the same time, the simple monoclinic phase of elemental Pu also becomes higher in energy at the equilibrium volume of the fcc phase. The new model is based on first-principles electronic structure calculations and captures the basic phase ordering of those calculations.

  12. Observation of the fcc-to-hcp transition in ensembles of argon nanoclusters.

    Science.gov (United States)

    Krainyukova, N V; Boltnev, R E; Bernard, E P; Khmelenko, V V; Lee, D M; Kiryukhin, V

    2012-12-14

    Macroscopic ensembles of weakly interacting argon nanoclusters are studied using x-ray diffraction in low vacuum. As the clusters grow by fusion with increasing temperature, their structure transforms from essentially face-centered cubic (fcc) to hexagonal close packed as the cluster size approaches ~10(5) atoms. The transformation involves intermediate orthorhombic phases. These data confirm extant theoretical predictions. They also indicate that growth kinetics and spatial constraints might play an important role in the formation of the fcc structure of bulk rare-gas solids, which still remains puzzling.

  13. Academic Training Lectures | FCC | 2-5 February

    CERN Multimedia

    2016-01-01

    Please note that the next series of Academic Training Lectures will take place from 2 to 5 February 2016.   Tuesday, 2 February 2016 from 10.30 a.m. to 12.30 p.m. in the Filtration Plant (Building 222-R-001) FCC 1: Introduction to FCC by Michael Benedikt FCC 2: FCC Physics - Challenges and Potentials by Christophe Grojean, Michelangelo Mangano https://indico.cern.ch/event/472105/   Wednesday, 3 February 2016 from 10.30 a.m. to 12.30 p.m in the Filtration Plant (Building 222-R-001) FCC 3: FCC hh Detectors and Experiments by Werner Riegler FCC 4: Experimental Measurements and Detectors for the FCC-ee by Mogens Dam https://indico.cern.ch/event/472106/   Thursday, 4 February 2016 from 10.30 a.m. to 12.30 p.m in the Filtration Plant (Building 222-R-001) FCC 5: FCC Hadron Collider Design by Daniel Schulte FCC 6: FCC Lepton Collider Design by Frank Zimmermann https://indico...

  14. 78 FR 49126 - Modernizing the FCC Form 477 Data Program

    Science.gov (United States)

    2013-08-13

    ... COMMISSION 47 CFR Parts 0, 1, and 43 Modernizing the FCC Form 477 Data Program AGENCY: Federal Communications... Docket No. 11-10, FCC 13-87, released on June 27, 2013. The complete text of this document is available for public inspection during regular business hours in the FCC Reference Information Center, Room...

  15. 47 CFR 95.117 - Where to contact the FCC.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Where to contact the FCC. 95.117 Section 95.117... SERVICES General Mobile Radio Service (GMRS) § 95.117 Where to contact the FCC. Additional GMRS information may be obtained from any of the following sources: (a) FCC National Call Center at 1-888-225-5322....

  16. 47 CFR 73.1225 - Station inspections by FCC.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Station inspections by FCC. 73.1225 Section 73... BROADCAST SERVICES Rules Applicable to All Broadcast Stations § 73.1225 Station inspections by FCC. (a) The... FCC during the station's business hours, or at any time it is in operation. (b) In the course of...

  17. 47 CFR 74.3 - FCC inspections of stations.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false FCC inspections of stations. 74.3 Section 74.3... Services in Part 74 § 74.3 FCC inspections of stations. (a) The licensee of a station authorized under this part must make the station available for inspection by representatives of the FCC during the...

  18. 76 FR 10827 - Modernizing the FCC Form 477 Data Program

    Science.gov (United States)

    2011-02-28

    ... COMMISSION 47 CFR Parts 1, 20, and 43 Modernizing the FCC Form 477 Data Program AGENCY: Federal... submitting comments. Federal Communications Commission's Web Site: http://fjallfoss.fcc.gov/ecfs2/ . Follow the instructions for submitting comments. People with Disabilities: Contact the FCC to...

  19. STUDIES OF FCC HEISENBERG ANTIFERROMAGNETS BY MONTE CARLO SIMULATION ON LARGE SPIN ARRAYS

    OpenAIRE

    Minor, W.; Giebultowicz, T.

    1988-01-01

    We report Monte Carlo studies of fcc Heisenberg antiferromagnets carried out on arrays with 108,000 spins. A lattice with only JNN ≠ 0 was found to exhibit a Type I AF order despite the disordered nature of its ground state. Contrary to previous reports, our data indicate in this case a first order phase transition.

  20. Interface effect of magnetic properties in Ni nanoparticles with a hcp core and fcc shell structure.

    Science.gov (United States)

    Choo, Seongmin; Lee, Kyujoon; Jo, Younghun; Yoon, Seon-Mi; Choi, Jae-Young; Kim, Jea-Young; Park, Jea-Hoon; Lee, Kyung-Jin; Lee, Jong-Heun; Jung, Myung-Hwa

    2011-07-01

    We have fabricated hexagonal close-packed (hcp) Ni nanoparticles covered by a face-centered cubic (fcc) Ni surface layer by polyol method. The magnetic properties have been investigated as a function of temperature and applied magnetic field. The magnetic behavior reveals that the system should be divided magnetically into three distinct phases with different origins. The fcc Ni phase on the shell contributes to the superparamagnetism through a wide temperature range up to 360 K. The hcp Ni phase at the core is associated with antiferromagnetic nature below 12 K. These observations are in good agreement with the X-ray absorption spectroscopy and magnetic circular dichroism measurements. In our particular case, the unique hcp core and fcc shell structure gives rise to an additional anomaly at 20 K in the zero-field-cooled magnetization curve. Its position is barely affected by the magnetic field but its structure disappears above 30 kOe, showing a metamagnetic transition in the magnetization versus magnetic field curve. This new phase originates from the magnetic exchange at the interface between the hcp and fcc Ni sublattices.

  1. Large difference in the elastic properties of fcc and hcp hard-sphere crystals

    NARCIS (Netherlands)

    Pronk, S.; Frenkel, D.

    2003-01-01

    We report a numerical calculation of the elastic constants of the fcc and hcp crystal phases of monodisperse hard-sphere colloids. Surprisingly, some of these elastic constants are very different (up to 20%), even though the free-energy, pressure, and bulk compressibility of the two crystal structur

  2. Defect Studies in bcc and fcc Iron

    OpenAIRE

    Ghorai, A.; Arjun Das

    2012-01-01

    Variation of vacancy formation energy (EF1v) with rc of Ashcroft's empty core model potential (AECMP) model for different exchange and correlation functions (ECFs) show almost independent nature but slight variation with ECF for both bcc α iron and fcc γ iron.

  3. Diffusion behavior and atomic mobilities for fcc Cu–Cr–Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Gaochi [School of Materials and Energy, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Liu, Yajun, E-mail: yajunliu@gatech.edu [School of Materials and Energy, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Lei, Fuyue [School of Materials and Energy, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Sheng, Guang [Scientific Forming Technologies Corporation, Columbus, OH 43235 (United States); Kang, Zhitao [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2015-11-15

    In this work, diffusion couples of fcc Cu–Cr–Ni alloys annealed at 1373 K for 80 h are investigated. The interdiffusion coefficients are retrieved from common compositions of two diffusion couples, which are then combined with thermodynamic descriptions to explore atomic mobilities of Cu, Cr and Ni in fcc Cu–Cr–Ni alloys within the CALPHAD framework. In order to confirm the quality of such kinetic characteristics, a comparison between calculated and experimentally measured concentration profiles of diffusion couples and diffusion paths in Gibbs triangle is made, where the agreement is excellent. The results of this study contribute to the establishment of a general Ni-based mobility database for alloy design. - Highlights: • Atomic mobilities of fcc Cu–Cr–Ni phases were determined. • Experimental interdiffusivities were critically evaluated. • Main and cross interdiffusivities show their peculiarities. • The profiles reveal kinetic importance for alloy microstructures.

  4. 47 CFR 95.428 - (CB Rule 28) How do I contact the FCC?

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false (CB Rule 28) How do I contact the FCC? 95.428... (CB Rule 28) How do I contact the FCC? (a) FCC National Call Center at 1-888-225-5322. (b) FCC World Wide Web homepage: http://www.fcc.gov. (c) In writing, to FCC, Attention: CB, 1270 Fairfield...

  5. Regeneration of Hydrotreating and FCC Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    CM Wai; JG Frye; JL Fulton; LE Bowman; LJ Silva; MA Gerber

    1999-09-30

    Hydrotreating, hydrocracking, and fluid catalytic cracking (FCC) catalysts are important components of petroleum refining processes. Hydrotreating and hydrocracking catalysts are used to improve the yield of high-quality light oil fractions from heavier crude oil and petroleum feedstocks containing high levels of impurities. FCC catalysts improve the yield of higher octane gasoline from crude oil. Residuum hydrotreating and cracking catalysts are susceptible to irreversible deactivation caused by adsorption of sulfur and by metals impurities, such as vanadium and nickel. The gradual buildup of these impurities in a hydrotreating catalyst eventually plugs the pores and deactivates it. Nickel and vanadium adversely affect the behavior of cracking catalysts, reducing product yield and quality. Replacing deactivated catalysts represents a significant cost in petroleum refining. Equally important are the costs and potential liabilities associated with treating and disposing spent catalysts. For example, recent US Environmental Protection Agency rulings have listed spent hydrotreating and hydrorefining catalysts as hazardous wastes. FCC catalysts, though more easily disposed of as road-base or as filler in asphalt and cement, are still an economic concern mainly because of the large volumes of spent catalysts generated. New processes are being considered to increase the useful life of catalysts or for meeting more stringent disposal requirements for spent catalysts containing metals. This report discusses a collaborative effort between Pacific Northwest National Laboratory (PNNL) and Phillips Petroleum, Inc., to identify promising chemical processes for removing metals adhered to spent hydrodesulfurization (HDS, a type of hydrotreating catalyst) and FCC catalysts. This study, conducted by PNNL, was funded by the US Department of Energy's Bartlesville Project Office. Fresh and spent catalysts were provided by Phillips Petroleum. The FCC catalyst was a rare

  6. Accurate Monte Carlo simulations on FCC and HCP Lennard-Jones solids at very low temperatures and high reduced densities up to 1.30.

    Science.gov (United States)

    Adidharma, Hertanto; Tan, Sugata P

    2016-07-07

    Canonical Monte Carlo simulations on face-centered cubic (FCC) and hexagonal closed packed (HCP) Lennard-Jones (LJ) solids are conducted at very low temperatures (0.10 ≤ T(∗) ≤ 1.20) and high densities (0.96 ≤ ρ(∗) ≤ 1.30). A simple and robust method is introduced to determine whether or not the cutoff distance used in the simulation is large enough to provide accurate thermodynamic properties, which enables us to distinguish the properties of FCC from that of HCP LJ solids with confidence, despite their close similarities. Free-energy expressions derived from the simulation results are also proposed, not only to describe the properties of those individual structures but also the FCC-liquid, FCC-vapor, and FCC-HCP solid phase equilibria.

  7. ADVANCE IN FCC TECHNOLOGY FOR RESID UPGRADING

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In order to treat residual oil in conventional FCC units, various aspects of catalyst improvement must be considered, such as how to get effective bottoms crackbility, lower selectivity of dry gas/coke or higher metals tolerance. Because residual oil contains many kinds of metals (Ni, V, Na), Conrandson carbon residue and asphaltene or basic nitrogen compunds, there are a lot of problems in FCC operation.   A new catalyst has been developed by means of modifying zeolite or matrix in our laboratory. The developed catalyst has a excellent bottoms crackbility, lower hydrogen / coke selectivity and higher metal tolerance. The features of the catalyst and the actual performance in our commercial units will be shown in this paper. The liquid product yield has been improved and the catalyst consumption has reduced.

  8. BSM searches at FCC-ee

    CERN Document Server

    Tay, Jala

    2016-01-01

    The discovery of the Higgs boson in 2012 was a great triumph for the LHC. The challenge now is to study it’s properties. In order to that an FCC project was proposed, such that at the beginning it will be used for ee collisions which will be a great deal in studying the Higgs properties because of it’s clean experimental environment and high luminosity, and then will be used for pp collisions to explore physics at higher energies. Here we will show how to generate events and plot graphs which will show how is the FCC beneficial for the Higgs study. We used delphes, pythia and ROOT to generate and analyze the events.

  9. Electrical Power Budget for FCC-ee

    CERN Document Server

    Aull, S.; Bozzini, D.; Brunner, O.; Burnet, J.-P.; Butterworth, A.; Calaga, R.; Jensen, E.; Mertens, V.; Milanese, A.; Nonis, M.; Oide, K.; Schwerg, N.; Tavian, L.; Wenninger, J.; Zimmermann, F.; Rinolfi, L; Blondel, A.; Koratzinos, M.; Gorgi Zadeh, S.

    2016-01-01

    We present a first rough estimate for the electrical power consumption of the FCC-ee lepton collider. This electrical power is dominated by the RF system, which provides the motivation for the ongoing R&D on highly efficient RF power sources. Other contributions come from the warm arc magnets, the cryogenics systems, cooling, ventilation, general services, the particle-physics detectors, and the injector complex.

  10. Beam Dynamics Challenges for FCC-ee

    CERN Document Server

    AUTHOR|(SzGeCERN)442987; Benedikt, Michael; Oide, Katsunobu; Bogomyagkov, Anton; Levichev, Evgeny; Migliorati, Mauro; Wienands, Uli

    2015-01-01

    The goals of FCC-ee include reaching luminosities of up to a few 1036 cm-2s-1 per interaction point at the Z pole or some 1034 cm-2s-1 at the ZH production peak, and pushing the beam energy up to ≥175 GeV, in a ring of 100 km circumference, with a total synchrotron-radiation power not exceeding 100 MW. A parameter baseline as well as high-luminosity crab-waist options were described in [1] and [2], respectively. The extremely high luminosity and resulting short beam lifetime (due to radiative Bhabha scattering) are sustained by top-up injection. The FCC-ee design status and typical beam parameters for different modes of operation are reported in [3]. One distinct feature of the FCC-ee design is its conception as a double ring, with separate beam pipes for the two counter-rotating (electron and positron) beams, resembling, in this aspect, the high-luminosity B factories PEP-II, KEKB and SuperKEKB as well as the LHC. The two separate rings do not only permit operation with a large number of bunches, up to a f...

  11. FCC riser quick separation system: a review

    Directory of Open Access Journals (Sweden)

    Zhi Li

    2016-10-01

    Full Text Available Abstract The riser reactor is the key unit in the fluid catalytic cracking (FCC process. As the FCC feedstocks become heavier, the product mixture of oil, gas and catalysts must be separated immediately at the outlet of the riser to avoid excessive coking. The quick separation system is the core equipment in the FCC unit. China University of Petroleum (Beijing has developed many kinds of separation system including the fender-stripping cyclone and circulating-stripping cyclone systems, which can increase the separation efficiency and reduce the pressure drop remarkably. For the inner riser system, a vortex quick separation system has been developed. It contains a vortex quick separator and an isolated shell. In order to reduce the separation time, a new type of separator called the short residence time separator system was developed. It can further reduce the separation time to less than 1 s. In this paper, the corresponding design principles, structure and industrial application of these different kinds of separation systems are reviewed. A system that can simultaneously realize quick oil gas separation, quick oil gas extraction and quick pre-stripping of catalysts at the end of the riser is the trend in the future.

  12. Orientation dependence of structural transition in fcc Al driven under uniaxial compression by atomistic simulations

    Institute of Scientific and Technical Information of China (English)

    Li Li; Shao Jian-Li; Duan Su-Qing; Liang Jiu-Qing

    2011-01-01

    By molecular dynamics simulations employing an embedded atom method potential, we have investigated structural transformations in single crystal Al caused by uniaxial strain loading along the[001],[011]and[111]directions.We find that the structural transition is strongly dependent on the crystal orientations. The entire structure phase transition only occurs when loading along the[001]direction, and the increased amplitude of temperature for[001]loading is evidently lower than that for other orientations. The morphology evolutions of the structural transition for [011]and[111]loadings are analysed in detail. The results indicate that only 20% of atoms transit to the hcp phase for[011]and[111]loadings, and the appearance of the hcp phase is due to the partial dislocation moving forward on {111}fcc family. For[011]loading, the hcp phase grows to form laminar morphology in four planes, which belong to the{111}fcc family;while for[111]loading, the hcp phase grows into a laminar structure in three planes, which belong to the {111}fcc family except for the(111)plane. In addition, the phase transition is evaluated by using the radial distribution functions.

  13. Catalyst fines behavior among FCC flue gas turbine blade rows -Effect of gaseous phase flow field distribution%烟气轮机叶片间隙中FCC催化剂细粉运动规律——气相流场分布的影响

    Institute of Scientific and Technical Information of China (English)

    杜玉朋; 赵辉; 杨朝合; 胡仁波; 张云

    2012-01-01

    针对近年来炼厂中出现的催化裂化烟气轮机内结垢严重的问题,首先采用数值模拟方法,探讨了烟机内部气相流场的分布.模拟结果表明:在动叶片的压力面上,气相速度分布较低、水气浓度分布较大以及温度分布较高的特点,使得随烟气进入烟机的催化剂颗粒极易在叶片压力面上堆积和熔融.此外,通过采用仪器分析的方法对新鲜剂、平衡剂和垢物进行了微观形貌(SEM)与矿物组成(XRD)等分析,结果表明:烟机叶片上的结垢主要是由催化剂颗粒堆积与颗粒中某些物质生成了低熔点共熔物共同作用的结果.所得结论可为进一步研究催化剂颗粒在烟机内的流动情况和揭示结垢机理等后续工作提供理论基础.%According to the problem of serious scale formation in the FCC flue gas turbines in many refineries, the distribution of gaseous phase flow field in flue gas turbines was studied by using a CFD-based numerical simulation method. The simulation shows that the distribution is characterized by low gas velocity, high humidity, and high temperature on the pressure-side of rotors, which makes the catalyst particles entrained by exhaust gases more readily accumulate and melt there. By means of instrumental analyses to fresh catalyst, equilibrium catalyst and scaling catalyst, including scanning electron microscope ( SEM) for micro-morphology analysis, and X-ray diffraction (XRD) for phase analysis, the catalyst scaling on the surface of blade is proved to be the concurrent consequence of particle accumulation and low-melting eutectic matter formation. The results provide a theoretical basis for further study on the catalyst particles behavior and the scaling mechanism in FCC flue gas turbines.

  14. 78 FR 28217 - Sunshine Act Meeting: FCC To Hold Open Commission Meeting

    Science.gov (United States)

    2013-05-14

    ... COMMISSION Sunshine Act Meeting: FCC To Hold Open Commission Meeting Thursday, May 9, 2013. The Federal... minute requests will be accepted, but may be impossible to fill. Send an email to: fcc504@fcc.gov fcc504@fcc.gov or call the Consumer & Governmental Affairs Bureau at 202-418-0530 (voice), 202-418-0432...

  15. PURIFIED WASTE FCC CATALYST AS A CEMENT REPLACEMENT MATERIAL

    Directory of Open Access Journals (Sweden)

    Danute Vaiciukyniene

    2015-06-01

    Full Text Available Zeolites are commonly used in the fluid catalytic cracking process. Zeolite polluted with oil products and became waste after some time used. The quantity of this waste inevitably rises by expanding rapidly oil industry. The composition of these catalysts depends on the manufacturer and on the process that is going to be used. The main factors retarding hydration process of cement systems and modifying them strength are organic compounds impurities in the waste FCC catalyst. The present paper shows the results of using purified waste FCC catalyst (pFCC from Lithuania oil refinery, as Portland cement replacement material. For this purpose, the purification of waste FCC catalyst (FCC samples was treated with hydrogen peroxide. Hydrogen peroxide (H2O2 is one of the most powerful oxidizers known. By acting of waste with H2O2 it can eliminate the aforementioned waste deficiency, and the obtained product becomes one of the most promising ingredients, in new advanced building materials. Hardened cement paste samples with FCC or pFCC were formed. It was observed that the pFCC blended cements developed higher strength, after 28 days, compared to the samples with FCC or reference samples. Typical content of Portland cement substituting does not exceed 30 % of mass of Portland cement in samples. Reducing the consumption of Portland cement with utilizing waste materials is preferred for reasons of environmental protection.

  16. FCC DeSOx and DeNOx additive technology

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The fluid catalytic cracking(FCC) is the principal gasoline-producing process in the refinery. Considerable amounts of harmful sulfur oxides and nitrogen oxides (SOx and NOx ) are generated with the FCC operation. Impacted by strengthening environmental regulations and the current global emphasis on environmental protection and pollution abatement, refiners have been meaning to look for effective ways to control and reduce SOx and NOx emissions. FCC DeSOx and DeNOx additives is the most promising measure. The present paper reviews the developments in FCC DeSOx and DeNOx additive technology based on the respective authors' works, the future directions of the technology are also discussed.

  17. Molecular dynamics simulations of hcp/fcc nucleation and growth in bcc iron driven by uniaxial compression.

    Science.gov (United States)

    Wang, B T; Shao, J L; Zhang, G C; Li, W D; Zhang, P

    2009-12-02

    Molecular dynamics simulations have been performed to study the structural transition in bcc iron under uniaxial strain loading. We found that the transition pressures are less dependent on the crystal orientations, ∼14 GPa for [001], [011], and [111] loadings. However, the pressure interval of a mixed phase for [011] loading is much shorter than loading along other orientations. In addition, the temperature increased amplitude for [001] loading is evidently lower than other orientations. The nucleation and growth of the hcp/fcc phases, and their crystal orientation dependence, were analyzed in detail, where the atom structure was presented by the topological medium-range-order analysis. For [001] compression, the hcp structure occurs first and grows into a laminar morphology in the (011)(bcc) plane with some fcc atoms as an intermediate structure. For loading along [011] and [111] directions, both hcp and fcc structure nucleation and growth along the {110}(bcc) planes are observed; their morphology is also discussed.

  18. Age-hardenability and related microstructural changes during and after phase transformation in an Au-Ag-Cu-based dental alloy

    Directory of Open Access Journals (Sweden)

    Hyung-Il Kim

    2013-02-01

    Full Text Available The aim of this study was to clarify how the microstructural changes during and after phase transformation determine the age-hardenability of an Au-Ag-Cu-based dental alloy. The rapid increase in hardness in the initial stage was the result of rapid atomic diffusion by spinodal decomposition into metastable Ag-rich' and Cu-rich' phases. The constant hardening after apparent initial hardening was the result of a subsequent transformation of the metastable Ag-rich' and Cu-rich' phases to the stable Ag-rich α1phase and AuCu I phase through the metastable AuCu I' phase. During the increase in hardness, fine block-like structure with high coherency formed in the grain interior, which changed to a fine cross-hatched structure. A relatively coarse lamellar structure composed of Ag-rich α1and AuCu I phases grew from the grain boundaries, initiating softening before the grain interior reached its maximum hardness. As a result, the spinodal decomposition attributed to rapid hardening by forming the fine block-like structure, and the subsequent ordering into AuCu I, which is a famous hardening mechanism, weakened its hardening effect by accelerating the lamellar-forming grain boundary reaction.

  19. Age-hardenability and related microstructural changes during and after phase transformation in an Au-Ag-Cu-based dental alloy

    Directory of Open Access Journals (Sweden)

    Hyung-Il Kim

    2012-01-01

    Full Text Available The aim of this study was to clarify how the microstructural changes during and after phase transformation determine the age-hardenability of an Au-Ag-Cu-based dental alloy. The rapid increase in hardness in the initial stage was the result of rapid atomic diffusion by spinodal decomposition into metastable Ag-rich' and Cu-rich' phases. The constant hardening after apparent initial hardening was the result of a subsequent transformation of the metastable Ag-rich' and Cu-rich' phases to the stable Ag-rich α1phase and AuCu I phase through the metastable AuCu I' phase. During the increase in hardness, fine block-like structure with high coherency formed in the grain interior, which changed to a fine cross-hatched structure. A relatively coarse lamellar structure composed of Ag-rich α1and AuCu I phases grew from the grain boundaries, initiating softening before the grain interior reached its maximum hardness. As a result, the spinodal decomposition attributed to rapid hardening by forming the fine block-like structure, and the subsequent ordering into AuCu I, which is a famous hardening mechanism, weakened its hardening effect by accelerating the lamellar-forming grain boundary reaction.

  20. REACTION CHEMISTRY RELATED TO FCC GASOLINE QUALITY

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    About 80% of the gasoline pool as a whole in China for supplying the domestic market at current stage directly originates from FCC units. Obviously, FCC gasoline quality is critical for refiners to meet the nations more and more stringent gasoline specifications. FCC process is expected to produce gasoline with reduced contents of olefins, aromatics, benzene, sulfur, and, contradictorily, still with high octane number.   Catalytic cracking process involves a series of acid catalyzed reactions. Bronsted acid sites dominate the surface of the catalyst used for FCC process. All the reactions of hydrocarbons in FCC process are based on carbonium ions of penta-coordinated, or carbenium ions of tri-coordinated. The monomolecular beta scission mechanism for alkane cracking explains that the cracking of carbon-carbon bonding occurs at the beta position to the carbon atom bearing positive charge, and hence forms two small hydrocarbon molecules: one alkane molecule and one olefin molecule. The molar ratio of alkane to olefin for the primary cracking product will be 1 and it will be less than 1 if the cracking reaction proceeds.   However, it is proved that bimolecular reaction pathways exist between surface carbenium ions and the feed molecules. The products of this bimolecular disproportionation reaction could be an alkane molecule and a newly formed carbenium ion. The better understanding of the reaction chemistry of FCC process based on monomolecular pathways and bimolecular pathways should be the basis for searching approaches to the improvement of FCC gasoline quality. In the complicated reaction scheme of the FCC process, the isomerization reaction leading to the formation of iso-alkanes is obviously a target reaction, which favors both olefin reduction and octane enhancement.   The cracking of small paraffin molecules, due to its limited number of reaction pathways and products, has been used to investigate cracking mechanism. In the present work the

  1. Tracking Simulation for Beam Loss Studies with Application to FCC

    CERN Document Server

    Boscolo, M

    2015-01-01

    We present first results on FCC-ee beam losses using a tracking simulation tool originally developed and successfully applied to Flav or Factories designs. After a brief description of the tool, we discuss first results obtained for FCC-ee at top energy, both for the Touschek effect and radiative Bhabha scattering.

  2. Major Technical Measures for Revamp of FCC Units in China

    Institute of Scientific and Technical Information of China (English)

    Li Wenjie

    2003-01-01

    FCC units are playing an important role at refineries, in particular at Chinese refineries. To cope with the current demand for better economic benefits, environmental protection and product slate adjustment, a host of FCC units need to be technically revamped. This article describes the practical processes, technologies and equipment to serve different revamp targets with analysis of two examples on revamp of commercial units.

  3. 47 CFR 76.1714 - FCC rules and regulations.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false FCC rules and regulations. 76.1714 Section 76.1714 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES MULTICHANNEL VIDEO AND CABLE TELEVISION SERVICE Documents to be Maintained for Inspection § 76.1714 FCC...

  4. 47 CFR 73.4000 - Listing of FCC policies.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Listing of FCC policies. 73.4000 Section 73... BROADCAST SERVICES Rules Applicable to All Broadcast Stations § 73.4000 Listing of FCC policies. The following sections list, solely for the purpose of reference and convenience, certain Policies of the...

  5. 47 CFR 95.225 - (R/C Rule 25) How do I contact the FCC?

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false (R/C Rule 25) How do I contact the FCC? 95.225... (R/C Rule 25) How do I contact the FCC? (a) FCC National Call Center at 1-888-225-5322. (b) FCC World Wide Web homepage: http://www.fcc.gov. (c) In writing, to FCC, Attention: R/C, 1270 Fairfield...

  6. Precision measurements of the top quark couplings at the FCC

    CERN Document Server

    AUTHOR|(CDS)2051271

    2015-01-01

    The design study of the Future Circular Colliders (FCC) in a 100-km ring in the Geneva area has started at CERN at the beginning of 2014, as an option for post-LHC particle accelerators. The study has an emphasis on proton-proton and electron-positron high-energy frontier machines. In the current plans, the first step of the FCC physics programme would exploit a high-luminosity e+e- collider called FCC-ee, with centre-of-mass energies ranging from below the Z pole to the t-tbar threshold and beyond, followed by 100\\,TeV proton-proton collisions as ultimate goal. When combined, these two steps offer a large palette of complementary measurements and sensitivity for new physics. In particular, the association of the FCC-ee and the FCC-hh allows measurements of the top-quark electroweak and Yukawa couplings to be performed with unrivaled precision.

  7. Adaptive GPC controller applied to FCC units; Controlador GPC adaptativo aplicado em unidades FCC

    Energy Technology Data Exchange (ETDEWEB)

    Melo Junior, Wilson S.; Rodrigues, Luiz Carlos A.; Arruda, L. Valeria R.; Neves Junior, Flavio [Centro Federal de Educacao Tecnologica do Parana, Curitiba, PR (Brazil). Programa de Pos-graduacao em Engenharia Eletrica e Informatica Industrial]. E-mail: melo, lcar, arruda, neves@cpgei.cefetpr.br

    2003-07-01

    This paper presents a predictive controller implementation applied on FCC unit. It is based on GPC (Generalized Predictive Control) algorithm and uses an adaptive model generated by real time identification using RLS (Recursive Least Squares) algorithm. A Kellogg Orthoflow F unit model is used to validate this implementation. In a FCC unit, the main reactions happen in riser and there are two regeneration stages. The controller is tuning to two manipulated variables and two controlled variables. The manipulated variables are the regenerated catalytic flow and the airflow rate to regenerator. The controlled variables are the riser temperature and the second stage regenerator temperature. The controller performance is evaluated by simulation and the obtained results assert the applicability of the proposed approach. (author)

  8. The influence of additions of Al and Si on the lattice stability of fcc and hcp Fe-Mn random alloys.

    Science.gov (United States)

    Gebhardt, T; Music, D; Ekholm, M; Abrikosov, I A; Vitos, L; Dick, A; Hickel, T; Neugebauer, J; Schneider, J M

    2011-06-22

    We have studied the influence of additions of Al and Si on the lattice stability of face-centred-cubic (fcc) versus hexagonal-closed-packed (hcp) Fe-Mn random alloys, considering the influence of magnetism below and above the fcc Néel temperature. Employing two different ab initio approaches with respect to basis sets and treatment of magnetic and chemical disorder, we are able to quantify the predictive power of the ab initio methods. We find that the addition of Al strongly stabilizes the fcc lattice independent of the regarded magnetic states. For Si a much stronger dependence on magnetism is observed. Compared to Al, almost no volume change is observed as Si is added to Fe-Mn, indicating that the electronic contributions are responsible for stabilization/destabilization of the fcc phase.

  9. Realizing high magnetic moments in fcc Fe nanoparticles through atomic structure stretch.

    Science.gov (United States)

    Baker, S H; Roy, M; Thornton, S C; Binns, C

    2012-05-02

    We describe the realization of a high moment state in fcc Fe nanoparticles through a controlled change in their atomic structure. Embedding Fe nanoparticles in a Cu(1-x)Au(x) matrix causes their atomic structure to switch from bcc to fcc. Extended x-ray absorption fine structure (EXAFS) measurements show that the structure in both the matrix and the Fe nanoparticles expands as the amount of Au in the matrix is increased, with the data indicating a tetragonal stretch in the Fe nanoparticles. The samples were prepared directly from the gas phase by co-deposition, using a gas aggregation source and MBE-type sources respectively for the nanoparticle and matrix materials. The structure change in the Fe nanoparticles is accompanied by a sharp increase in atomic magnetic moment, ultimately to values of ~2.5 ± 0.3 μ(B)/atom .

  10. 9th FCC-ee (TLEP) Physics Workshop

    CERN Document Server

    2015-01-01

    This is the 9th in the series of FCCee/TLEP-related workshops. It follows on from the sucessful 8th TLEP workshop that took place in Paris on 27-29 October 2014, and the FCC kick-off meeting held on 12-15 February 2014 at University of Geneva. The workshop is open to all FCC-ee /TLEP design study members, and more generally to all interested in a precision Z, W, H, top factory. The focus will be on physics and experiments at the FCC-ee, but a more general session is organized the first day (Tuesday 3 February afternoon) with presentations about the FCC design study as a whole, and on machine and physics for the FCC-ee and the FCC-hh, with synergies and complementarities. This session is aimed at a larger audience, towards improving the project visibility in Italy. It will be followed by a social dinner in the evening. The workshop starts on Tuesday at 13:30 and ends on Thursday 16:00. Registration is now open, please proceed at your earliest convenience! Please visit the FCC-ee / TLEP web site, and subscrib...

  11. FCC-ee Physics workshop | 19-21 June 2014

    CERN Multimedia

    2014-01-01

    The 7th FCC-ee/TLEP workshop, the first after the FCC kick-off in February 2014, will be focused on physics and experiments.     It will take place on 19-21 June at CERN in the TH auditorium. The registration is open and the agenda is available on the indico web page: http://indico.cern.ch/event/313708/. You are all cordially invited to attend! This will be the first in a series of workshops that will lead us to the first FCC-ee physics milestone, a document defining the physics landscape and study plans, required for March 2015. More information can be found here. FCC-ee is a high-luminosity Z, W, Higgs and top factory, to be hosted in a 100km tunnel, possibly as the first step towards a 100 TeV pp collider FCC-hh. These two machines are being studied within the FCC design study. High precision, high statistics and a clean environment are the tools available in FCC-ee to shed light on the unknown physics that underlies present mysteries: dark matter, the baryon asymmetry of th...

  12. 75 FR 62818 - Sunshine Act Meeting; FCC To Hold Open Commission Meeting Thursday, October 14, 2010

    Science.gov (United States)

    2010-10-13

    ... COMMISSION Sunshine Act Meeting; FCC To Hold Open Commission Meeting Thursday, October 14, 2010 October 7... consider a Third Report and Order and Order on Reconsideration that will make changes to the FCC's Cable... be accepted, but may be impossible to fill. Send an e-mail to: fcc504@fcc.gov or call the...

  13. 47 CFR 95.422 - (CB Rule 22) How do I answer correspondence from the FCC?

    Science.gov (United States)

    2010-10-01

    ... from the FCC? 95.422 Section 95.422 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED... You Need to Know § 95.422 (CB Rule 22) How do I answer correspondence from the FCC? (a) If it appears to the FCC that you have violated the Communications Act or these rules, the FCC may send you...

  14. 76 FR 6473 - Sunshine Act; FCC To Hold Open Commission Meeting Tuesday, February 8, 2011

    Science.gov (United States)

    2011-02-04

    ... COMMISSION Sunshine Act; FCC To Hold Open Commission Meeting Tuesday, February 8, 2011 February 1, 2011. The... Competition Title: Reform of the FCC Form 477 Data Program (WC Docket No. 11-10); Development of Nationwide... impossible to fill. Send an e-mail to: fcc504@fcc.gov or call the Consumer & Governmental Affairs Bureau...

  15. 76 FR 20976 - Wireline Competition Bureau Releases 2011 Annual Telecommunications Reporting Worksheet (FCC Form...

    Science.gov (United States)

    2011-04-14

    ... COMMISSION Wireline Competition Bureau Releases 2011 Annual Telecommunications Reporting Worksheet (FCC Form... Reporting Worksheet (FCC Form 499-A) and accompanying instructions. Filers may now submit their FCC Form 499-A to the Universal Service Administrative Company. DATES: Filers must submit the FCC Form...

  16. Study on Reduction of Sulfur Content in FCC Gasoline

    Institute of Scientific and Technical Information of China (English)

    Hou Dianguo

    2003-01-01

    Reduction of sulfur content in FCC gasoline was studied in a fixed fluid bed (FFB) unit by using metal-modified LV-23 FCC catalyst. The results showed that the sulfur content in FCC gasoline could be reduced with LV-23 catalyst modified with zinc, palladium, zinc-palladium, zinc-cobalt, and zinc-nickel. Among these metals or metal combinations, palladium-containing catalyst was the most effective. Desulfurization of the heavy fraction of FCC gasoline was more effective than full-range gasoline under the same conditions with palladium-containing catalysts. A high reaction temperature was favorable to desulfurization, but it would reduce the yield of liquid product. After desulfurization reaction, the olefin content of product gasoline decreased while the aromatic and iso-alkane contents increased. Removal of thiophene and benzothiophene is higher.

  17. Selective Hydrodesulfurization of FCC Gasoline Using LH-07 Catalyst

    Institute of Scientific and Technical Information of China (English)

    Da Jianwen; Han Xinzhu; Liu Aihua; Xu Xinzhong

    2002-01-01

    @@ 1.Introduction Since the environmental regulations are increasingly strin gent than ever, the production of clean automobile fuel is a vital target in China, especially after China has become a WTO member. However, the sulfur content in gasoline pool of China is still very high. Over 95% of the sulfur in gaso line pool comes from FCC naphtha. It is necessary to remove sulfur in FCC naphtha.

  18. Spent FCC catalyst for improving early strength Portland cement

    OpenAIRE

    Borrachero Rosado, María Victoria; Monzó Balbuena, José Mª; Paya Bernabeu, Jorge Juan; Vunda, Christian; VELÁZQUEZ RODRÍGUEZ, SERGIO; Soriano Martinez, Lourdes

    2014-01-01

    Spent fluid catalytic cracking (FCC) catalyst from the petrol industry has proven to be a very active pozzolanic material. This behavior leads to an additional increase in the strength of the mortar that contains this catalyst. Pozzolanic effects tend to be considered for periods above three days, whereas in shorter times, the influence of pozzolan is usually negligible. The reactivity of FCC is so high, however, that both pozzolanic effects and acceleration of cement hydration are evident in...

  19. FCC Catalysts to Meet Demand of New Era

    Institute of Scientific and Technical Information of China (English)

    Yu Daping

    2008-01-01

    The CGP series FCC catalysts for manufacture of clean gasoline and propylene and the catalyst RSC-2006 for processing inferior residuum with high yield of light distillates are novel catalysts jointly developed by Qilu Catalyst Branch Company of SINOPEC Corp. and the Research Institute of Petroleum Processing (RIPP). The results of commercial application of these catalysts have revealed that they can satisfactorily meet the requirements for environmental protection, good economic benefits and capability for processing inferior FCC feed under new circumstances.

  20. Diffusion behavior of Cr diluted in bcc and fcc Fe: Classical and quantum simulation methods

    Energy Technology Data Exchange (ETDEWEB)

    Ramunni, Viviana P., E-mail: vpram@cnea.gov.ar [CONICET, Avda. Rivadavia 1917, Cdad. de Buenos Aires C.P. 1033 (Argentina); Comisión Nacional de Energía Atómica, Gerencia Materiales, Av. Del Libertador 8250, C1429BNP Ciudad de Buenos Aires (Argentina); Rivas, Alejandro M.F. [CONICET, Avda. Rivadavia 1917, Cdad. de Buenos Aires C.P. 1033 (Argentina); Comisión Nacional de Energía Atómica, Departamento de Física Teórica, Tandar, Av. Del Libertador 8250, C1429BNP Ciudad de Buenos Aires (Argentina)

    2015-07-15

    We characterize the atomic mobility behavior driven by vacancies, in bcc and fcc Fe−Cr diluted alloys, using a multi-frequency model. We calculate the full set of the Onsager coefficients and the tracer self and solute diffusion coefficients in terms of the mean jump frequencies. The involved jump frequencies are calculated using a classical molecular static (CMS) technique. For the bcc case, we also perform quantum calculations based on the density functional theory (DFT). There, we show that, in accordance with Bohr's correspondence principle, as the size of the atomic cell (total number of atoms) is increased, quantum results with DFT recover the classical ones obtained with CMS calculations. This last ones, are in perfect agreement with available experimental data for both, solute and solvent diffusion coefficients. For high temperatures, in the fcc phase where no experimental data are yet available, our CMS calculations predict the expected solute and solvent diffusion coefficients. - Graphical abstract: Display Omitted - Highlights: • Comparison of diffusion coefficients obtained from classical and quantum methods. • We perform our calculations in diluted bcc/fcc Fe–Cr alloy. • Magnetic and phonon effects must be taken into account. • Classical calculations are in perfect agreement with experimental data.

  1. Comparing the structural stability of PbS nanocrystals assembled in fcc and bcc superlattice allotropes.

    Science.gov (United States)

    Bian, Kaifu; Wang, Zhongwu; Hanrath, Tobias

    2012-07-04

    We investigated the structural stability of colloidal PbS nanocrystals (NCs) self-assembled into superlattice (SL) allotropes of either face-centered cubic (fcc) or body-centered cubic (bcc) symmetry. Small-angle X-ray scattering analysis showed that the NC packing density is higher in the bcc than in the fcc SL; this is a manifestation of the cuboctahedral shape of the NC building block. Using the high-pressure rock-salt/orthorhombic phase transition as a stability indicator, we discovered that the transition pressure for NCs in a bcc SL occurs at 8.5 GPa, which is 1.5 GPa higher than the transition pressure (7.0 GPa) observed for a fcc SL. The higher structural stability in the bcc SL is attributed primarily to the effective absorption of loading force in specific SL symmetry and to a lesser extent to the surface energy of the NCs. The experimental results provide new insights into the fundamental relationship between the symmetry of the self-assembled SL and the structural stability of the constituent NCs.

  2. Development of OCDMA system based on Flexible Cross Correlation (FCC) code with OFDM modulation

    Science.gov (United States)

    Aldhaibani, A. O.; Aljunid, S. A.; Anuar, M. S.; Arief, A. R.; Rashidi, C. B. M.

    2015-03-01

    The performance of the OCDMA systems is governed by numerous quantitative parameters such as the data rate, simultaneous number of users, the powers of transmitter and receiver, and the type of codes. This paper analyzes the performance of the OCDMA system using OFDM technique to enhance the channel data rate, to save power and increase the number of user of OSCDMA systems compared with previous hybrid subcarrier multiplexing/optical spectrum code division multiplexing (SCM/OSCDM) system. The average received signal to noise ratio (SNR) with the nonlinearity of subcarriers is derived. The theoretical results have been evaluated based on BER and number of users as well as amount of power saved. The proposed system gave better performance and save around -6 dBm of the power as well as increase the number of users twice compare to SCM/OCDMA system. In addition it is robust against interference and much more spectrally efficient than SCM/OCDMA system. The system was designed based on Flexible Cross Correlation (FCC) code which is easier construction, less complexity of encoder/decoder design and flexible in-phase cross-correlation for uncomplicated to implement using Fiber Bragg Gratings (FBGs) for the OCDMA systems for any number of users and weights. The OCDMA-FCC_OFDM improves the number of users (cardinality) 108% compare to SCM/ODCMA-FCC system.

  3. Orbitide Composition of the Flax Core Collection (FCC).

    Science.gov (United States)

    Burnett, Peta-Gaye Gillian; Olivia, Clara Marisa; Okinyo-Owiti, Denis Paskal; Reaney, Martin John Tarsisius

    2016-06-29

    The flax (Linum usitatissimum L.) core collection (FCC) was regenerated in Saskatoon, Saskatchewan and Morden, Manitoba in 2009. Seed orbitide content and composition from successfully propagated plants of 391 accessions were analyzed using high-throughput analyses employing high-performance liquid chromatography (HPLC) with reverse-phase monolithic HPLC columns and diode array detection (HPLC-DAD). Seed from plants regenerated in Morden had comparatively higher orbitide content than those grown in Saskatoon. Concentrations of orbitides encoded by contig AFSQ01016651.1 (1, 3, and 8) were higher than those encoded by AFSQ01025165.1 (6, 13, and 17) for most accessions in both locations. The cultivar 'Primus' from Poland and an unnamed accession (CN 101580 of unknown origin) exhibited the highest ratio of sum of [1,3,8] to a sum of [6,13,17]. Conversely, the lowest orbitide concentrations and ratio of [1,3,8] to [6,13,17] were observed in cultivars 'Hollandia' and 'Z 11637', both from The Netherlands. Orbitide expression did not correlate with flax morphological and other chemical traits.

  4. Nanotwinned fcc metals: Strengthening versus softening mechanisms

    Science.gov (United States)

    Stukowski, A.; Albe, K.; Farkas, D.

    2010-12-01

    The strengthening effect of twins in nanocrystalline metals has been reported both in experiment and simulation. While twins are mostly considered as effective barriers to dislocation slip transfer, they can also provide nucleation sites for dislocations or migrate during the deformation process, thereby contributing to plasticity. By comparing twinned and nontwinned samples, we study the effect of twins on the deformation behavior of nanocrystalline Cu and Pd using atomistic simulations. While Cu shows hardening due to the presence of twins, Pd shows the opposite effect. A quantitative dislocation analysis method is applied, which allows to analyze dislocation interactions with twin planes and grain boundaries and to measure dislocation, stacking fault, and twin-boundary densities as functions of strain. A statistical analysis of the occurring dislocation types provides direct evidence for the role of twin boundaries as effective sources for twinning dislocations, which are the reason for the observed softening in some fcc materials. In addition, we discuss how the orientation of the loading direction with respect to the twin planes affects the response of nanotwinned Cu and Pd.

  5. Investigation on Modification of NaY Zeolite and Its Behaviors in Selective Adsorptive Desulfurization of FCC gasoline

    Institute of Scientific and Technical Information of China (English)

    Zhu Heli; Song Lijuan; Gao Xiang; Wang Hongguo; Zhang Xiaotong; Sun Zhaolin

    2009-01-01

    NaY zeolite was modified with oxalic acid, and Ce(Ⅳ)Y(1) zeolite was obtained via liquid phase ion exchange between the modified NaY zeolite and cerium nitrate. The Ce(Ⅳ)Y(2) zeolite was obtained via liquid phase ion exchange between NaY zeolite and cerium nitrate. The performance of two Y zeolites ICe(Ⅳ)Y(1) and Ce(Ⅳ)Y(2)] was compared through static selective adsorptive desulfurization of FCC gasoline at room tem-perature and normal pressure. The sulfur compounds and contents of the FCC gasoline were analyzed by microcoulometry and GC-SCD chromatogram. The results showed that the effect of adsorptive desulfurization of FCC gasoline achieved by Ce(Ⅳ)Y(1) zeolite was better than that of Ce(Ⅳ)Y(2) zeolite. The rate for adsorp-tive desulfurization of FCC gasoline by Ce(Ⅳ)Y(1) zeolite and Ce(Ⅳ)Y(2) zeolite was 85.0% and 62.4%, respectively. The Ce(Ⅳ)Y(1) zeolite could adsorb DMTs, which could not be adsorbed by Ce(Ⅳ)Y(2) zeolite. The rate of regeneration of extruded Ce(Ⅳ)Y(1)zeolite was 95.5%.

  6. The fcc-bcc crystallographic orientation relationship in AlxCoCrFeNi high-entropy alloys

    NARCIS (Netherlands)

    Rao, J. C.; Ocelik, V.; Vainchtein, D.; Tang, Z.; Liaw, P. K.; De Hosson, J. Th. M.

    2016-01-01

    This paper concentrates on the crystallographic-orientation relationship between the various phases in the Al-Co-Cr-Fe-Ni high-entropy alloys. Two types of orientation relationships of bcc phases (some with ordered B2 structures) and fcc matrix were observed in Al0.5CoCrFeNi and Al0.7CoCrFeNi alloys

  7. Outline and Status of the FCC-ee Design Study

    CERN Document Server

    Zimmermann, Frank

    2015-01-01

    The Update of the European Strategy for Particle Physics in 2013 [1] declared as its second highest priority that “…to propose an ambitious post-LHC accelerator project….., CERN should undertake design studies for accelerator projects in a global context,…with emphasis on proton-proton and electron-positron high-energy frontier machines…”. In response to this request, the global Future Circular Collider (FCC) study is designing a 100-TeV proton collider (FCC-hh) in a new ~100 km tunnel near Geneva, a high-luminosity electron-positron collider (FCC-ee) as a potential intermediate step, and a lepton-hadron option (FCC-he). The FCC study comprises accelerators, technology, infrastructure, detector, physics, concepts for worldwide data services, international governance models, and implementation scenarios. The FCC study is mandated to deliver a Conceptual Design Report and preliminary cost estimate by the time of the next European Strategy Update expected for 2019. As of July 2015, 58 institutes from...

  8. Downflow - the FCC of the future; Downflow - o FCC do futuro

    Energy Technology Data Exchange (ETDEWEB)

    Pinho, Andrea de Rezende; Huziwara, Wilson Kenzo [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES). Tecnologias de FCC]. E-mail: gerla@cenpes.petrobras.com.br; Ramos, Jose Geraldo Furtado; Silva, Mauro [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES). Engenharia Basica de FCC, Coque e Separacao]. E-mail: jgramos@cenpes.petrobras.com.br

    2002-03-01

    Thermal cracking reactions are not selective in prime products such as naphtha and LPG, which favors the formation of coke and fuel gas in the RISER reactor of the FCC. For this reason, thermal cracking is gradually being reduced and, consequently, the participation of catalytic cracking in this process is being increased. One of the ways to minimize thermal cracking in the reactor is to promote flow the closest possible to plug flow, through downward flow reactors, more commonly known as DOWNER or DOWNFLOW. Innumerable studies already done at CENPES in hot pilot units have demonstrated the attractiveness of this technology, through the utilization of cold demonstration units and through a complete knowledge of fluidization and Engineering techniques at PETROBRAS. The DOWNFLOW presents significant conversion gains, of 2.2% wt, basically due to the increase in gasoline and LPG production, resulting in a specific profitability increase of 6.7 US$/t of feed. This is possible due to the low selectivity of the DOWNFLOW to the coke. This technology offers a promising alternative for the future, keeping in mind the gradual increase in the participation of national petroleum from the Campos Basin in the list of feeds processed at the FCC units. (author)

  9. 47 CFR 95.219 - (R/C Rule 19) How do I answer correspondence from the FCC?

    Science.gov (United States)

    2010-10-01

    ... from the FCC? 95.219 Section 95.219 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED... You Need to Know § 95.219 (R/C Rule 19) How do I answer correspondence from the FCC? (a) If it appears to the FCC that you have violated the Communications Act or FCC rules, the FCC may send you...

  10. Color Octet Electron Search Potential of the FCC Based e-p Colliders

    CERN Document Server

    Acar, Y C; Oner, B B; Sultansoy, S

    2016-01-01

    Resonant production of color octet electron, e_{8}, at the FCC based ep colliders has been analyzed. It is shown that e-FCC will cover much a wider region of e_{8} masses compared to the LHC. Moreover, with highest electron beam energy, e_{8} search potential of the e-FCC exceeds that of FCC pp collider. If e_{8} is discovered earlier by the FCC pp collider, e-FCC will give opportunity to handle very important additional information. For example, compositeness scale can be probed up to hundreds TeV region.

  11. Effect of the Heusler phase formation on the magnetic behavior of the Cu–10 wt.%Mn alloy with Al and Ag additions

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, T.M., E-mail: thaisa.mary@gmail.com [Instituto de Química – UNESP, Caixa Postal 355, 14801-970 Araraquara, SP (Brazil); Adorno, A.T.; Santos, C.M.A. [Instituto de Química – UNESP, Caixa Postal 355, 14801-970 Araraquara, SP (Brazil); Silva, R.A.G. [Departamento de Ciências Exatas e da Terra – UNIFESP, 09972-270 Diadema, SP (Brazil); Magnani, M. [Instituto de Química – UNESP, Caixa Postal 355, 14801-970 Araraquara, SP (Brazil)

    2015-09-15

    Highlights: • The presence of the Cu{sub 2}MnAl phase was observed in annealed alloys. • Al and Ag additions shift the equilibrium concentration to higher Al values. • There is a correlation between the Ag-rich phase and the Cu{sub 2}MnAl phase. - Abstract: In this work, the formation of the Cu{sub 2}AlMn Heusler phase and its influence on the magnetic behavior of the Cu–Mn–Al–Ag alloys in the range of 8–10 wt.% of aluminum and 2–4 wt.% of silver were studied using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and saturation magnetization measurements at 4 K. The results showed that there is a correlation between the presence of the Ag-rich phase and the formation of the Cu{sub 2}MnAl phase.

  12. Topological Dirac nodal lines and surface charges in fcc alkaline earth metals

    Science.gov (United States)

    Hirayama, Motoaki; Okugawa, Ryo; Miyake, Takashi; Murakami, Shuichi

    2017-01-01

    In nodal-line semimetals, the gaps close along loops in k space, which are not at high-symmetry points. Typical mechanisms for the emergence of nodal lines involve mirror symmetry and the π Berry phase. Here we show via ab initio calculations that fcc calcium (Ca), strontium (Sr) and ytterbium (Yb) have topological nodal lines with the π Berry phase near the Fermi level, when spin-orbit interaction is neglected. In particular, Ca becomes a nodal-line semimetal at high pressure. Owing to nodal lines, the Zak phase becomes either π or 0, depending on the wavevector k, and the π Zak phase leads to surface polarization charge. Carriers eventually screen it, leaving behind large surface dipoles. In materials with nodal lines, both the large surface polarization charge and the emergent drumhead surface states enhance Rashba splitting when heavy adatoms are present, as we have shown to occur in Bi/Sr(111) and in Bi/Ag(111).

  13. Impact of FCC regenerator design in the NOx emissions

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Hugo Borges; Sandes, Emanuel Freire; Gilbert, William Richard; Roncolatto, Rodolfo Eugenio; Gobbo, Rodrigo; Casavechia, Luiz Carlos; Candido, William Victor Carlos [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil); Bridi, Patricia Elaine [Possebon Engenharia, Sao Mateus do Sul, PR (Brazil)

    2012-07-01

    Fluid Catalytic Cracking (FCC) is the main point source of NOx in the refinery and it is responsible for at least 20% of the total NOx emissions from the refineries. The thermal NOx formation in the FCC regenerator is negligible. However, half of the feed nitrogen is converted to coke, and is burned in the regenerator. The majority of coke nitrogen is reduced to N2 and less than 10% is converted to NOx. This number may vary significantly with the oxygen excess in the flue gas and other operational conditions. With the purpose of evaluating the impact of different regenerator designs in NOx formation, several tests were carried out in the PETROBRAS FCC prototype unit. The test unit is equipped with adiabatic insulation and a CO boiler, allowing it to reproduce the heat balance of a commercial FCC and to operate either in full combustion or partial combustion. Two different designs of FCC regenerators were evaluated: single stage regenerator (the existing configuration) and two stage regenerator, with the catalyst bed divided into two sections by a structured packing baffle. It was observed in the tests that the combustion regime had a very strong effect on NOx formation. In full combustion, the effect of the FCC operating variables: excess oxygen, combustion promoter content in catalyst and regenerator design could be identified. The two stage configuration was capable of decreasing NOx emissions by 30%. In partial combustion, the effect of the CO-boiler variables on NOx emissions was overwhelming, but the use of the structured packing baffle was able to improve the catalyst regeneration.(author)

  14. FCC FAMILY TECHNOLOGY BRIDGING PETROLEUM REFINING WITH PETROCHEMICAL INDUSTRY

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    FCC family technologies,such as DCC,MGG and CPP,take the advantages of both thermal and catalytic reactions. A zeolite containing material is acted as heat carrier and catalyst as well. Versatile objectives can be achieved through regulating the catalyst formulation and optimizing the process variables. The ethylene,propylene and isobutylene yields from these FCC family technologies can be 24.3%, 22.9% and 6.1%,respectively,with heavy feeds. The cracked naphtha is rich in toluene and xylenes.

  15. Impact of magnetic fluctuations on lattice excitations in fcc nickel.

    Science.gov (United States)

    Körmann, Fritz; Ma, Pui-Wai; Dudarev, Sergei L; Neugebauer, Jörg

    2016-02-24

    The spin-space averaging formalism is applied to compute atomic forces and phonon spectra for magnetically excited states of fcc nickel. Transverse and longitudinal magnetic fluctuations are taken into account by a combination of magnetic special quasi random structures and constrained spin-density-functional theory. It turns out that for fcc Ni interatomic force constants and phonon spectra are almost unaffected by both kinds of spin fluctuations. Given the computational expense to simulate coupled magnetic and atomic fluctuations, this insight facilitates computational modeling of magnetic alloys such as Ni-based superalloys.

  16. Quantitative comparison between simulated and experimental FCC rolling textures

    DEFF Research Database (Denmark)

    Wronski, M.; Wierzbanowski, K.; Leffers, Torben

    2015-01-01

    The degree of similarity between simulated and experimental fcc rolling textures is characterized by a single scalar parameter. The textures are simulated with a relatively simple and efficient 1-point model which allows us to vary the strength of the interaction between the grains and the surrou......The degree of similarity between simulated and experimental fcc rolling textures is characterized by a single scalar parameter. The textures are simulated with a relatively simple and efficient 1-point model which allows us to vary the strength of the interaction between the grains...

  17. Dynamic simulation of industrial Fluidized-bed Catalytic Cracking - FCC unit

    Energy Technology Data Exchange (ETDEWEB)

    Secchi, Argimiro R.; Neumann, Gustavo A.; Trierweiler, Jorge O. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Dept. de Engenharia Quimica]. E-mail: arge@enq.ufrgs.br; gneumann@enq.ufrgs.br; jorge@enq.ufrgs.br; Santos, Marlova G. [PETROBRAS S.A., Canoas, RS (Brazil). Refinaria Alberto Pasqualini]. E-mail: marlova@petrobras.com.br

    2000-07-01

    In this work a mathematical model for the dynamic simulation of the Fluidized-bed Catalytic Cracking (FCC) Reactor, to be used in the analysis, control, and optimization of this system is developed. Based on the full range of published data in FCC performance and kinetic rates, and adapted to the industrial unit of the PETROBRAS' Alberto Pasqualini Refinery (REFAP), an integrated dynamic model is build up. The model is sufficiently complex to capture the major dynamics effects that occur in this system. The regenerator is modeled as emulsion and bubble phases that exchange mass and heat. The riser is modeled as an adiabatic plug flow reactor. The fluid dynamic is taking into account for the catalyst circulation, and the dynamics of the gas phase and the riser are also considered into the model. The model, represented by a non-linear system of differential-algebraic equations, was written in language C and implemented in MATLAB/SIMULINK. The results are compared with the data obtained from the industrial plant of REFAP. (author)

  18. Phenomenological study of monomer adsorption on fcc (335) surfaces with application to CO, O, and N(2) adsorption on Pt(335).

    Science.gov (United States)

    Phares, Alain J; Grumbine, David W; Wunderlich, Francis J

    2009-01-20

    We extend our recent study of adsorption on fcc (112) to fcc (335) surfaces, still considering only first- and second-neighbor interactions with repulsive first-neighbors. We consider the adsorbate-substrate interaction on the step sites of one of the two edges of the infinitely long terraces to be different from that on the remaining sites. The adsorption features on fcc (335) surfaces are richer than those on fcc (112), which can be attributed to the fact that the equilateral triangular terraces are now four-atoms wide rather than three. Our approach is independent of the chemical composition of the substrate and adsorbates and consequently may be applied to a variety of adsorption systems on fcc (335) surfaces which satisfy the limitations of our model. The basic question that our phenomenological approach intends to answer is: what are the constraints that can be obtained on the interaction energies from the experimental observation of one or more phases? This question is answered in the cases of CO, O, and N(2) adsorbed on Pt(335).

  19. 47 CFR 97.27 - FCC modification of station license grant.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false FCC modification of station license grant. 97... RADIO SERVICES AMATEUR RADIO SERVICE General Provisions § 97.27 FCC modification of station license grant. (a) The FCC may modify a station license grant, either for a limited time or for the duration...

  20. Congress, the FCC and Children's Television Regulation: A Shift in the Balance of Power.

    Science.gov (United States)

    Markin, Karen

    The Federal Communications Commission (FCC) of the late 1980s appeared to pursue its own agenda of broadcast deregulation, notwithstanding congressional pressures. The apparent power shift is evident in a case study of the interactions between Congress and the FCC on the subject of children's television. In the early 1970s, the FCC tended to…

  1. Commercial Test of Multi-functional Desulfurizing Agent TS-01 for Gasoline in FCC Process

    Institute of Scientific and Technical Information of China (English)

    Cai Zhi; Wu Yingjian; Yu Weisheng

    2003-01-01

    Experimental use of multi-functional desulfurizing agent TS-01 for FCC gasoline in the FCC unitof SINOPEC Jiujiang Company shows that the multi-functional desulfurizing agent can effectivelyremove various kinds of sulfur in FCC gasoline and diesel fuel and fulfill passivation on heavy metals.

  2. 47 CFR 11.21 - State and Local Area plans and FCC Mapbook.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false State and Local Area plans and FCC Mapbook. 11... (EAS) General § 11.21 State and Local Area plans and FCC Mapbook. EAS plans contain guidelines which... are consistent with national plans, FCC regulations, and EAS operation. (a) The State plan...

  3. 47 CFR 73.1226 - Availability to FCC of station logs and records.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Availability to FCC of station logs and records... Availability to FCC of station logs and records. The following shall be made available to any authorized representative of the FCC upon request: (a) Station records and logs shall be made available for inspection...

  4. 47 CFR 0.409 - Commission policy on private printing of FCC forms.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Commission policy on private printing of FCC... ORGANIZATION General Information General § 0.409 Commission policy on private printing of FCC forms. The Commission has established a policy regarding the printing of blank FCC forms by private companies if...

  5. 76 FR 12308 - Modernizing the FCC Form 477 Data Program; Correction

    Science.gov (United States)

    2011-03-07

    ... COMMISSION 47 CFR Parts 1, 20, and 43 Modernizing the FCC Form 477 Data Program; Correction AGENCY: Federal... FCC Form 477. Inadvertently the Comment Filing Procedures section of the February 28, 2011 publication... February 28, 2011 (76 FR 10827) relating to the modernization of the FCC Form 477. The document (FR...

  6. Deformation microstructure and orientation of F.C.C. crystals

    DEFF Research Database (Denmark)

    Liu, Q.; Hansen, N.

    1995-01-01

    The effect of crystallographic orientation on the microstructural evolution in f.c.c. metals with medium to high stacking fault energy is analyzed. This analysis is based on a literature review of the behaviour of single crystals and polycrystals supplemented with an experimental study of cold...

  7. DISLOCATION STRUCTURE OF FCC COPPER/BCC IRON INTERPHASE INTERFACES

    OpenAIRE

    C Forwood

    1990-01-01

    The Burgers vectors and geometry of the interfacial dislocation structure in fcc/bcc interfaces in a Cu+25 wt.% Fe alloy are analysed using TEM and the technique of image matching. The Burgers vectors are shown to be differences of the Cu and Fe lattice vectors and the interfacial structure is interpreted in terms of a CSL/DSC model.

  8. Cross-twinning model of fcc crystal growth

    NARCIS (Netherlands)

    Waal, van de Benjamin W.

    1996-01-01

    The theory developed in 1960 by Wagner, Hamilton and Seidensticker (WHS-theory) to explain observed crystal growth phenomena in Ge is critically reviewed and shown to be capable of explaining preservation of ABC stacking order in two dimensions in fcc crystals of effectively spherical closed shell m

  9. FCC-hh Hadron Collider - Parameter Scenarios and Staging Options

    CERN Document Server

    Benedikt, Michael; Schulte, Daniel; Zimmermann, F; Syphers, M J

    2015-01-01

    FCC-hh is a proposed future energy-frontier hadron collider, based on dipole magnets with a field around 16 T installed in a new tunnel with a circumference of about 100 km, which would provide proton collisions at a centre-of-mass energy of 100 TeV, as well as heavy-ion collisions at the equivalent energy. The FCC-hh should deliver a high integrated proton-proton luminosity at the level of several 100 fb−1 per year, or more. The challenges for operating FCC-hh with high beam current and at high luminosity include the heat load from synchrotron radiation in a cold environment, the radiation from collision debris around the interaction region, and machine protection. In this paper, starting from the FCC-hh design baseline parameters we explore different approaches for increasing the integrated luminosity, and discuss the impact of key individual pa- rameters, such as the turnaround time. We also present some injector considerations and options for early hadron-collider operation.

  10. Development of the Novel Grid Type Multi-stage Regeneration Technology for FCC Unit

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhenqian; Tian Geng

    2006-01-01

    Based on the results of cold model tests, LPEC has developed a technology for regeneration of FCC catalyst in a regenerator with novel grid type internals in order to intensify the contact between gas and solid and enhance the coke burning efficiency in the regenerator. Test results have revealed that the density change in the fluidized bed equipped with grid internals is relatively homogeneous and the bubbling frequency is obviously reduced with apparent improvements in the dead fluidized zone adjacent to the regenerator wall, and this device can be applied to the intensified regeneration of catalyst in the FCC regenerator.The commercial application of this device in a 0.8 Mt/a RFCCU at the refinery A had indicated that the carbon content of regenerated catalyst was reduced to 0.03% from 0.18%, and the amount of coke burned was increased by 5% with a definite reduction in main air consumption of the regenerator and some density reduction in the dilute phase section of the regenerator.

  11. The FCC-ee design study: luminosity and beam polarization

    CERN Document Server

    Koratzinos, M

    2015-01-01

    The FCC-ee accelerator is considered within the FCC design study as a possible first step towards the ultimate goal of a 100 TeV hadron collider. It is a high luminosity e+e- storage ring collider, designed to cover energies of around 90, 160, 240 and 350GeV ECM (for the Z peak, the WW threshold, the ZH and ttbar cross-section maxima respectively) leading to different operating modes. We report on the current status of the design study, on the most promising concepts and relevant challenges. The expected luminosity performance at all energies, and first studies on transverse polarization for beam energy calibrations will be presented.

  12. Volume variation of Gruneisen parameters of fcc transition metals

    Indian Academy of Sciences (India)

    C V Pandya; P R Vyas; T C Pandya; V B Gohel

    2002-02-01

    The volume variation of the Gruneisen parameters of ten fcc transition metals, up to 40% compression, has been studied on the basis of a model approach proposed by Antonov et al. The results are reasonably good for six metals except for Rh, Ag, Au and Ni when compared with available experimental and other theoretical values. The model requires an appropriate modification for Rh, Ag, Au and Ni.

  13. FCC-ee final focus with chromaticity correction

    CERN Document Server

    Garcia, H; Tomás, R

    2014-01-01

    A 100 km circular electron-positron collider is considered as one of the possible future high energy facilities. In order to achieve a high luminosity, strong beam focusing at the Interaction Point (IP) is used requiring the correction of the chromatic aberrations. In this paper we study preliminary designs of a Final Focus System (FFS) for the FCC-ee collider with chromatic correction. Beam orbit stability and dynamic aperture calculations are also presented.

  14. Dynamic Aperture Studies for the FCC-ee

    CERN Document Server

    Medina, L; Tomas, R; Zimmermann, F

    2015-01-01

    Dynamic aperture (DA) studies have been conducted on the latest Future Circular Collider – ee (FCC-ee) lattices as a function of momentum deviation.Two different schemes for the interaction region are used, which are connected to the main arcs: the crab waist approach, developed by BINP, and an update to the CERN design where the use of crab cavities is envisioned. The results presented show an improvement in the performance of both designs.

  15. First results for a FCC-hh ring optics design

    CERN Document Server

    Chance, Antoine; Payet, Jacques; Alemany Fernandez, Reyes; Holzer, Bernhard; Schulte, Daniel

    2015-01-01

    The first order considerations of the optics for the FCC-hh ring are presented. The arc cell is generated taking into account some general considerations like the whole circumference, maximum gradients and lengths of the elements in the cell. The integration of the insertion regions started. Three types of Dispersion Suppressors (DIS) are studied. The sensitivity of the arc parameters to these layout considerations is studied in more detail. An alternative layout is shown as well.

  16. Thermal stability and hcp-fcc allotropic transformation in supported Co metal catalysts probed near operando by ferromagnetic NMR.

    Science.gov (United States)

    Andreev, Andrey S; d'Espinose de Lacaillerie, Jean-Baptiste; Lapina, Olga B; Gerashenko, Alexander

    2015-06-14

    Despite the fact that cobalt based catalysts are used at the industrial scale for Fischer-Tropsch synthesis, it is not yet clear which cobalt metallic phase is actually at work under operando conditions and what is its state of dispersion. As it turns out, the different phases of metallic cobalt, fcc and hcp, give rise to distinct ferromagnetic nuclear magnetic resonance. Furthermore, within one Co metal particle, the occurrence of several ferromagnetic domains of limited sizes can be evidenced by the specific resonance of Co in multi-domain particles. Consequently, by ferromagnetic NMR, one can follow quantitatively the sintering and phase transitions of dispersed Co metal particles in supported catalysts under near operando conditions. The minimal size probed by ferromagnetic Co NMR is not precisely known but is considered to be in the order of 10 nm for supported Co particles at room temperature and increases to about 35 nm at 850 K. Here, in Co metal Fischer-Tropsch synthesis catalysts supported on β-SiC, the resonances of the fcc multi-domain, fcc single-domain and hcp Co were clearly distinguished. A careful rationalization of their frequency and width dependence on temperature allowed a quantitative analysis of the spectra in the temperature range of interest, thus reflecting the state of the catalysts under near operando conditions that is without the uncertainty associated with prior quenching. The allotropic transition temperature was found to start at 600-650 K, which is about 50 K below the bulk transition temperature. The phase transition was fully reversible and a significant part of the hcp phase was found to be stable up to 850 K. This anomalous behavior that was observed without quenching might prove to be crucial to understand and model active species not only in catalysts but also in battery materials.

  17. Structure and magnetic properties of hcp and fcc nanocrystalline thin Ni films and nanoparticles produced by radio frequency magnetron sputtering.

    Science.gov (United States)

    Kapaklis, Vassilios; Pappas, Spiridon D; Poulopoulos, Panagiotis; Trachylis, Dimitrios; Schweiss, Peter; Politis, Constantin

    2010-09-01

    We report on the growth of thin Ni films by radio frequency magnetron sputtering in Ar-plasma. The growth temperature was about 350 K and the films were deposited on various substrates such as glass, silicon, sapphire and alumina. The thickness of the thinnest films was estimated by the appearance of Kiessig fringes up to about 2theta = 8 degrees in the small-angle X-ray diffraction pattern, as expected for high-quality atomically-flat thin films. With the help of this, a quartz balance system was calibrated and used for measuring the thickness of thicker samples with an accuracy of better than 5%. Structural characterization via X-ray diffraction and high resolution transmission electron microscopy revealed an Ar-gas pressure window, where single phase hcp Ni films may be grown. The magnetic response of the Ni films was checked at room temperature via a newly established and fully automatic polar magneto-optic Kerr effect magnetometer. The hcp films show no magnetic response. Interestingly, the magnetic saturation field of fcc films deposited at low Ar pressure is comparable to the one of bulk Ni, while the one of fcc films deposited at high Ar pressures is decreased, revealing the presence of residual strain in the films. Finally, it is shown that it is possible to form films which contain magnetic Ni fcc nanoparticles in a non-magnetic hcp matrix, i.e., a system interesting for technological applications demanding a single Ni target for its production.

  18. Attrition Resistant Fischer-Tropsch Catalysts Based on FCC Supports

    Energy Technology Data Exchange (ETDEWEB)

    Adeyiga, Adeyinka

    2010-02-05

    Commercial spent fluid catalytic cracking (FCC) catalysts provided by Engelhard and Albemarle were used as supports for Fe-based catalysts with the goal of improving the attrition resistance of typical F-T catalysts. Catalysts with the Ruhrchemie composition (100 Fe/5 Cu/4.2 K/25 spent FCC on mass basis) were prepared by wet impregnation. XRD and XANES analysis showed the presence of Fe{sub 2}O{sub 3} in calcined catalysts. FeC{sub x} and Fe{sub 3}O{sub 4} were present in the activated catalysts. The metal composition of the catalysts was analyzed by ICP-MS. F-T activity of the catalysts activated in situ in CO at the same conditions as used prior to the attrition tests was measured using a fixed bed reactor at T = 573 K, P = 1.38 MPa and H{sub 2}:CO ratio of 0.67. Cu and K promoted Fe supported over Engelhard provided spent FCC catalyst shows relatively good attrition resistance (8.2 wt% fines lost), high CO conversion (81%) and C{sub 5}+ hydrocarbons selectivity (18.3%).

  19. Formation of bcc and fcc during the coalescence of free and supported Fe and Ni clusters.

    Science.gov (United States)

    Li, Guojian; Wang, Qiang; Sui, Xudong; Wang, Kai; Wu, Chun; He, Jicheng

    2015-09-07

    The formation of bcc and fcc during the coalescence of free and supported Fe and Ni clusters has been studied by molecular dynamics simulation using an embedded atom method. Structural evolution of the clusters, coalesced under varying temperature, Ni content and substrate conditions, was explored by interatomic energy, snapshots, pair distribution functions and bond order parameters. The results show that the formation of bcc and fcc is strongly related to Ni content, substrate and coalescence temperature. Free clusters coalesced at 1200 K form bcc at lower Ni contents with fcc forming at higher Ni concentrations and no observable coexistence of bcc and fcc. Differences in coalescence at 1000 K result from the coexistence of bcc and fcc within the Ni range of 50-70%. Free clusters supported on disordered Ni substrates were shown to transform from spherical morphology to islands of supported clusters with preferred epitaxial orientation. The Ni content required to form bcc and fcc coexistence on supported clusters at 1000 K decreased to 30-50% Ni. Free clusters possessing bcc and fcc generally stacked along the bcc (110) and fcc (111) facets, whereas supported clusters stacked along the (111) bcc and (100) fcc planes. Structural transformation was induced by clusters containing greater numbers of atoms. Spread over the substrate enhanced interatomic energy, order substrates affect the epitaxial growth direction and increase the melting points of the supported clusters. This study can be used to predict the nature of fcc and bcc formation in Fe-Ni films.

  20. FCC/HCP martensitic transformation and shape memory effect in Co-Al binary system%Co-Al二元系中的fcc/hcp马氏体相变和形状记忆效应

    Institute of Scientific and Technical Information of China (English)

    大森俊洋

    2005-01-01

    It is known that pure Co undergoes martensitic transformation from γ phase (fcc) to ε phase (hcp) by the movement of a/6 Shockley partial dislocations at around 400 ℃, however, there have been few systematic works on the SM effect in Co and Co-based alloys. In this study, the fcc/hcp martensitic transformation and the SM effect were investigated in Co-Al binary alloys(mole fraction of Al=0~16%).The γ/ε martensitic transformation temperatures were found from the DSC measurements to decrease with increasing Al content, while the transformation temperature hystereses were observed to increase from 60 ℃ at x(Al)=0 to 150 ℃at x(Al)= 16%. The SM effect evaluated by a conventional bending test was enhanced by the addition of Al over 4%(mole fraction) and Co-Al alloys containing over 10%(mole fraction) exhibit a good SM effect associated with the hcp →fcc reverse transformation above 200 ℃. The SM effect was significantly improved by precipitation ofβ (B2) phase and the maximal shape recovery strain of 2. 2% was obtained, which can be explained by precipitation hardening. The crystallographic orientations between theβ, ε and γ phases were also determined. Finally, the magnetic properties were investigated and it was found that the Curie temperature and saturation magnetization of Co-14% Al(mole fraction) are 690 ℃and 120 emu/g, respectively. It is concluded that the Co-Al alloys hold promise as new high-temperature and ferromagnetic SM alloys.

  1. Isomorphic phase transformation in shocked cerium using molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Dupont, Virginie [Los Alamos National Laboratory; Germann, Timothy C [Los Alamos National Laboratory; Chen, Shao - Ping [Los Alamos National Laboratory

    2010-08-12

    Cerium (Ce) undergoes a significant ({approx}16%) volume collapse associated with an isomorphic fcc-fcc phase transformation when subject to compressive loading. We present here a new Embedded Atom Method (EAM) potential for Cerium that models two minima for the two fcc phases. We show results from its use in Molecular Dynamics (MD) simulations of Ce samples subjected to shocks with pressures ranging from 0.5 to 25 GPa. A split wave structure is observed, with an elastic precursor followed by a plastic wave. The plastic wave causes the expected fcc-fcc phase transformation. Comparisons to experiments and MD simulations on Cesium (Cs) indicate that three waves could be observed. The construction of the EAM potential may be the source of the difference.

  2. Isomorphic phase transformation in shocked Cerium using molecular dynamics

    Directory of Open Access Journals (Sweden)

    Germann T.C.

    2011-01-01

    Full Text Available Cerium (Ce undergoes a significant (∼16% volume collapse associated with an isomorphic fcc-fcc phase transformation when subject to compressive loading. We present here a new Embedded Atom Method (EAM potential for Cerium that models two minima for the two fcc phases. We show results from its use in Molecular Dynamics (MD simulations of Ce samples subjected to shocks with pressures ranging from 0.5 to 25 GPa. A split wave structure is observed, with an elastic precursor followed by a plastic wave. The plastic wave causes the expected fcc-fcc phase transformation. Comparisons to experiments and MD simulations on Cesium (Cs indicate that three waves could be observed. The construction of the EAM potential may be the source of the difference.

  3. Prototyping a coherent framework for full, fast and parameteric detector simulation for the FCC project

    CERN Document Server

    Hrdinka, Julia; Salzburger, Andreas; Hegner, Benedikt

    2015-01-01

    The outstanding success of the physics program of the Large Hadron Collider (LHC) including the discovery of the Higgs boson shifted the focus of part of the high energy physics community onto the planning phase for future circular collider (FCC) projects. A proton-proton collider is in consideration, as well as an electron-positron ring and an electron-proton option as potential LHC successor projects. Common to all projects is the need for a coherent software framework in order to carry out simulation studies to establish the potential physics reach or to test different technol- ogy approaches. Detector simulation is a particularly necessary tool needed for design studies of different detector concepts and to allow establishing the relevant performance parameters. In ad- dition, it allows to generate data as input for the development of reconstruction algorithms needed to cope with the expected future environments. We present a coherent framework that combines full, fast and parametric detector simulation e...

  4. CFD Study of Industrial FCC Risers: The Effect of Outlet Configurations on Hydrodynamics and Reactions

    Directory of Open Access Journals (Sweden)

    Gabriela C. Lopes

    2012-01-01

    Full Text Available Fluid catalytic cracking (FCC riser reactors have complex hydrodynamics, which depend not only on operating conditions, feedstock quality, and catalyst particles characteristics, but also on the geometric configurations of the reactor. This paper presents a numerical study of the influence of different riser outlet designs on the dynamic of the flow and reactor efficiency. A three-dimensional, three-phase flow model and a four-lump kinetic scheme were used to predict the performance of the reactor. The phenomenon of vaporization of the liquid oil droplets was also analyzed. Results showed that small changes in the outlet configuration had a significant effect on the flow patterns and consequently, on the reaction yields.

  5. Spin-driven symmetry breaking in the frustrated fcc pyrite MnS2.

    Science.gov (United States)

    Kimber, Simon A J; Chatterji, Tapan

    2015-06-10

    We report the characterisation of natural samples of the cubic pyrite mineral MnS2 using very high resolution synchrotron x-ray diffraction techniques. At low temperatures we find a new low temperature polymorph, which results from coupling between magnetic and lattice degrees of freedom. Below the magnetic ordering temperature T(N) = 48 K, we detect a pseudo-tetragonal distortion with a tiny c/a ratio of 1.0006. The structure can be refined in the space group Pbca The symmetry lowering reduces magnetic frustration in the fcc Mn(2+) lattice and is likely responsible for the previously reported lock-in of the magnetic propagation vector. This behaviour is similar to the spin-Peierls phase transitions reported in other three-dimensional Heisenberg magnets like the chromate spinels.

  6. Properties of FeNiB-based metallic glasses with primary BCC and FCC crystallisation products

    Energy Technology Data Exchange (ETDEWEB)

    Uriarte, J.L. E-mail: euronano@ltpcm.inpg.fr; Yavari, A.R.; Surinach, S.; Rizzi, P.; Heunen, G.; Baricco, M.; Baro, M.D.; Kvick, A

    2003-01-01

    FeSiB tapes have long been commercialised for their excellent soft-magnetic properties but do not manifest a glass transition temperature T{sub g} as crystallisation intervenes. In this work, we present the crystallisation and properties of two Fe-based glasses, which show a glass transition before crystallisation. Using Ni and Co substitution, we can design glasses that form primary FCC or BCC FeNiCo solutions in their first stage of crystallisation followed by the formation of the metastable (FeNiCo){sub 4}B (C{sub 6}Cr{sub 23}-type cF116) intermetallic phase. Thermal and structural and magnetic properties were compared during heat treatment.

  7. The microstructure and phase relationships in rapidly solidified type 304 stainless steel powders

    Science.gov (United States)

    Wright, Richard N.; Flinn, John E.; Korth, Gary E.; Bae, Jung Chan; Kelly, Thomas F.

    1988-10-01

    The microstructure and relative amounts of fcc and bcc phases have been studied for rapidly solidified Type 304 stainless steel powders produced by vacuum gas atomization (VGA) and centrifugal atomization (CA). The VGA powder solidifies with a cellular microstructure while the CA powder has a dendritic microstructure. The volume fraction of fcc phase in the CA powder is found to increase from 40 Pct to 97 Pct with increasing particle size from 30 to 125 µm. In the VGA powder, the volume fraction of fcc phase is found to decrease from about 90 Pct to 77 Pct over the same range of particle sizes. The origins of the fcc and bcc phases in each powder are considered. It is concluded that bcc is present as both a primary crystallization phase in the smaller CA particles (<75 µm) and as compositionally stabilized eutectic ferrite at the cell walls of particles of both CA and VGA powders in which fcc was the primary crystallization phase.

  8. On the Convergence of the Electronic Structure Properties of the FCC Americium (001) Surface

    OpenAIRE

    Gao, Da; Ray, Asok K.

    2006-01-01

    Electronic and magnetic properties of the fcc Americium (001) surface have been investigated via full-potential all-electron density-functional electronic structure calculations at both scalar and fully relativistic levels. Effects of various theoretical approximations on the fcc Am (001) surface properties have been thoroughly examined. The ground state of fcc Am (001) surface is found to be anti-ferromagnetic with spin-orbit coupling included (AFM-SO). At the ground state, the magnetic mome...

  9. Can the Lennard-Jones solid be expected to be fcc?

    OpenAIRE

    Waal, de, SAJ Bas

    1991-01-01

    The structure of the Lennard-Jones solid, obtained by molecular-dynamics simulation of crystallization in the supercooled liquid, may be fcc, although the hcp structure is energetically more favorable. This could derive from the cubic symmetry of the fcc lattice, allowing lattice defects that are not possible in the hcp arrangement, but are essential to crystal growth in the simulated liquid. Two crossing stacking faults in a small fcc crystallite can produce nonvanishing, growth-promoting, b...

  10. FLEXIBLE NEW FCC TECHNOLOGY TO MEET THE EVER CHANGING MARKET DEMAND

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Being a main conversion process,FCC is evolving toward processing more heavier and dirtier feeds,and to produce varied product slates to meet the local market demands.Frequently many of the product demands made on the FCC process operator are seemingly contradictory.However,with the advance of FCC process and catalyst manufacture technology over the past few years,these contradictories can be solved profitbaly.Daqing VR FCC,maximized distillate production(MDP) technique and the maximizing gas and distillate(MGD) process are the examples.Specific data of each example will be revealed and shown on the poster.

  11. Enhanced propylene production in FCC by novel catalytic materials

    Energy Technology Data Exchange (ETDEWEB)

    Kelkar, C.P.; Harris, D.; Xu, M.; Fu, J. [BASF Catalyst LLC, Iselin, NJ (United States)

    2007-07-01

    Fluid catalytic cracking is expected to increasingly supply the additional incremental requirements for propylene. The most efficient route to increase propylene yield from an FCC unit is through the use of medium pore zeolites such as ZSM-5. ZSM-5 zeolite cracks near linear olefins in the gasoline range to LPG olefins such as propylene and butylenes. This paper will describe catalytic approaches to increase gasoline range olefins and the chemistry of ZSM-5 to crack those olefins. The paper will also describe novel catalytic materials designed to increase propylene. (orig.)

  12. Polarization Issues in the $e\\pm$ FCC

    Energy Technology Data Exchange (ETDEWEB)

    Gianfelice-Wendt, E.

    2015-08-10

    After the Higgs boson discovery at LHC, the international physics community is considering the next energy frontier circular collider (FCC). A pp collider of 100 km with a center of mass energy of about 100 TeV is believed to have the necessary discovery potential. The same tunnel could host first a e+e- collider with beam energy ranging between 45 and 175 GeV. In this paper preliminary considerations on the possibility of self-polarization for the e± beams are presented.

  13. Effect of vanadium on the deactivation of FCC catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Roncolatto, R.E.; Lam, Y.L. [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas. Div. de Catalisadores]. E-mail: roncolatto@cenpes.petrobras.com.br; y12@cenpes.petrobras.com.br

    1998-06-01

    This work provides concrete evidence that causes the destruction of the zeolite in the FCC catalysts by a mechanism of acid attack or solid-solid transformation, as well as additional dealumination of the zeolite framework in the presence of steam and at high temperature. While these effects resulted in the reduction in crystallinity (zeolite Y content), specific area and unit cell size of the Y zeolite as the amount of vanadium in the catalysts increased, the reduction in activity was the most pronounced. The differences in these behaviors were interpreted and the model can be used for better catalyst formulation or screening. (author)

  14. Polarization at TLEP/FCC-ee: ideas and estimates

    CERN Document Server

    Mane, S R

    2014-01-01

    I examine various ideas for radiative polarization at TLEP/FCC-ee and formulate some estimates for the polarization buildup time and the asymptotic polarization. Using wigglers, a useful degree of polarization (for energy calibration), with a time constant of about 1 h, may be possible up to the threshold of $W$ pair production. At higher energies such as the threshold of Higgs production, attaining a useful level of polarization may be difficult in a planar ring. With Siberian Snakes, wigglers and some imagination, polarization of reasonable magnitude, with a reasonable time constant (of not more than about 1 h), may be achievable at very high energies.

  15. Alkali cation specific adsorption onto fcc(111) transition metal electrodes.

    Science.gov (United States)

    Mills, J N; McCrum, I T; Janik, M J

    2014-07-21

    The presence of alkali cations in electrolyte solutions is known to impact the rate of electrocatalytic reactions, though the mechanism of such impact is not conclusively determined. We use density functional theory (DFT) to examine the specific adsorption of alkali cations to fcc(111) electrode surfaces, as specific adsorption may block catalyst sites or otherwise impact surface catalytic chemistry. Solvation of the cation-metal surface structure was investigated using explicit water models. Computed equilibrium potentials for alkali cation adsorption suggest that alkali and alkaline earth cations will specifically adsorb onto Pt(111) and Pd(111) surfaces in the potential range of hydrogen oxidation and hydrogen evolution catalysis in alkaline solutions.

  16. EFFECT OF VANADIUM ON THE DEACTIVATION OF FCC CATALYSTS

    Directory of Open Access Journals (Sweden)

    Roncolatto R.E

    1998-01-01

    Full Text Available This work provides concrete evidence that vanadium causes the destruction of the zeolite in the FCC catalysts by a mechanism of acid attack or solid-solid transformation, as well as additional dealumination of the zeolite framework in the presence of steam and at high temperature. While these effects resulted in the reduction in crystallinity (zeolite Y content, specific area and unit cell size of the Y zeolite as the amount of vanadium in the catalysts increased, the reduction in activity was the most pronounced. The differences in these behaviors were interpreted and the model can be used for better catalyst formulation or screening.

  17. Analysis of fluid dynamics to the riser of a FCC cold pilot plant aided with response surface methodology; Analise da fluidodinamica em um riser de FCC de uma unidade piloto a frio com auxilio da metodologia de superficie de resposta

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Kamylla A.L. dos; Luna-Finkler, Christine L.; Lima Filho, Hilario J.B. de [Universidade Federal de Pernambuco (UFPE), Vitoria de Santo Antao, PE (Brazil); Benachour, Mohand; Dantas, Carlos Costa; Santos, Valdemir A. dos [Universidade Catolica de Pernambuco (UNICAP), Recife, PE (Brazil)

    2012-07-01

    It was planned and executed the implementation of a Central Composite Rotatable Design (CCRD) to the riser of a FCC (Fluid Catalytic Cracking) cold pilot plant, to identify the basic fluid dynamic characteristics of this type of reactor. The Fluid Catalytic Cracking is the major process in oil refineries in the world. It is realized in a vertical cylindrical reactor called riser, with a short contact time between the cracking catalyst and vacuum gas oil vapors. The constant evolution of the FCC process has required the analysis of fluid dynamics using computational fluid dynamics (CFD) software. However, analysis of images produced by the application of CFD to study of risers requires preliminary concepts of the relationship between response variables and independent variables. With the CCRD implementation was performed a total of 12 experiments, being 4 full factorial, 4 axial points and 4 central points. The dependent variables were the velocities of the components (cracking catalyst and compressed air) and the pressure drop in the riser. There was a great contribution of solids flow rate for the solid phase velocity and for the pressure drop. The effects of interaction between the flow rate phases are considerably senses in pressure drop through the riser, however, for the velocities of both phases this interaction becomes negligible. (author)

  18. Monitoring of mass flux of catalyst FCC in a Cold Pilot Unit by gamma radiation transmission; Monitoramento da taxa de fluxo do catalisador FCC em uma unidade piloto a frio por medicao de transmissao gama

    Energy Technology Data Exchange (ETDEWEB)

    Brito, Marcio Fernando Paixao de

    2014-09-01

    This paper proposes a model for monitoring the mass flow of catalyst FCC - Fluid Catalytic Cracking - in a CPU - Cold Pilot unit - due to the injection of air and solid by gamma radiation transmission. The CPU simplifies the process of FCC, which is represented by the catalyst cycle, and it was constructed of acrylic, so that the flow can be visualized. The CPU consists of riser separation chamber and return column, and simulates the riser reactor of the FCC process. The catalyst is injected into the column back to the base of the riser, an inclined tube, where the compressed air means that there fluidization along the riser. When the catalyst comes in the separation chamber, the solid phase is sent to the return column, and the gas phase exits the system through one of the four cyclones at the top of the separation chamber. The transmission gamma of measures will be made by means of three test sections that have source and detector shielded. Pressure drop in the riser measurements are made through three pressure gauges positioned on the riser. The source used was Am-241 gamma ray with energy of 60 keV, and detector used was a scintillator of NaI (Tl) of 2 {sup x} 2{sup .} Measures the mass flow of catalyst are made by varying the seal of the catalyst, and density of solid in the riser because with the combination of these measures can determine the speed of the catalyst in the riser. The results show that the transmission gamma is a suitable technique for monitoring the flow of catalyst, flow model in CPU is annular, tomography third generation is more appropriate to study the CPU and the density variation in circulation in the CPU decreases linearly with increasing air flow. (author)

  19. Topological Dirac nodal lines and surface charges in fcc alkaline earth metals

    Science.gov (United States)

    Hirayama, Motoaki; Okugawa, Ryo; Miyake, Takashi; Murakami, Shuichi

    2017-01-01

    In nodal-line semimetals, the gaps close along loops in k space, which are not at high-symmetry points. Typical mechanisms for the emergence of nodal lines involve mirror symmetry and the π Berry phase. Here we show via ab initio calculations that fcc calcium (Ca), strontium (Sr) and ytterbium (Yb) have topological nodal lines with the π Berry phase near the Fermi level, when spin–orbit interaction is neglected. In particular, Ca becomes a nodal-line semimetal at high pressure. Owing to nodal lines, the Zak phase becomes either π or 0, depending on the wavevector k, and the π Zak phase leads to surface polarization charge. Carriers eventually screen it, leaving behind large surface dipoles. In materials with nodal lines, both the large surface polarization charge and the emergent drumhead surface states enhance Rashba splitting when heavy adatoms are present, as we have shown to occur in Bi/Sr(111) and in Bi/Ag(111). PMID:28074835

  20. Constitutive Model for an FCC Single-Crystal Material

    Institute of Scientific and Technical Information of China (English)

    DING Zhi-ping; LIU Yi-lun; YIN Ze-yong; YANG Zhi-guo; CHENG Xiao-ming

    2006-01-01

    Talking into account the effects that the components of tension stresses couple with components of torsion stresses when off-axis loads are applied to orthotropic materials.Hill's yield criterion for plastically orthotropic solids is modified by adding an invariant that is composed of the product item of quadratic components of the deviatoric siress tensor,and a new yield criteflon is put forward in terms of the characteristics of the face-centered cubic(FCC) single-crystal material.The correlation of prediction and experiments is very good.and the new criterion is used to predict the yield stresses of an intemal single-crystal,Nickel-based superalloy,DD3,which is more accurate than that Of Hill's at 760°C.Equivalent stress and strain that adapt to the new criterion are defined.Thinking of the yield function as a plastic potential function from the associated flow rule.the elastic-plastic constitutive model for the FCC single-crystal material is constructed,and the corresponding elastic-plastic matrix iseduced.The new yield criterion and its equivalent stress and strain will be reduced to Von Mises' yield criterion and corresponding equivalent stress and strain for isotropic materials.

  1. Electronic Structure of Crystalline Buckyballs: fcc-C60

    Science.gov (United States)

    Jalali-Asadabadi, Saeid; Ghasemikhah, E.; Ouahrani, T.; Nourozi, B.; Bayat-Bayatani, M.; Javanbakht, S.; Aliabad, H. A. Rahnamaye; Ahmad, Iftikhar; Nematollahi, J.; Yazdani-Kachoei, M.

    2016-01-01

    The electronic properties of pristine fcc-C60 are calculated by utilizing a variety of density functional theory (DFT) approaches including the Perdew-Burke-Ernzerhof generalized gradient approximation (PBE-GGA), PBE-GGA+DFT-D3(vdW), Engel and Vosko GGA (EV-GGA), GGA plus Hubbard U parameter (GGA+U), hybrids Becke-Perdew-Wang hybrid functional (B3PW91), Becke-Lee-Yang-Parr hybrid functional (B3LYP), the PBE exchange-correlation functional (PBE0), and Tran and Blaha regular and non-regular modified Becke and Johnson (TB-mBJ) potential within a DFT frame work using augmented plane waves plus local orbital method. The comparison of the calculated results with the experimental values shows that the non-regular TB-mBJ method reproduces a correct experimental direct band gap of 2.12 eV at X symmetry for this compound. The effectiveness of this theoretical approach in the reproduction of the experimental band gap is due to the proper treatment of the electrons in the interstitial region of the crystal. Our results show that the C60 clusters are weakly interacting with each other in the fcc crystal. This study also reveals that the five-fold degeneracies of the isolated C60 molecule due to its icosahedral symmetry are completely lifted at an X symmetry point by the crystal field.

  2. A method to measure vacuum birefringence at FCC-ee

    CERN Document Server

    Uggerhøj, Ulrik I

    2016-01-01

    It is well-known that the Heisenberg-Euler-Schwinger effective Lagrangian predicts that a vacuum with a strong static electromagnetic field turns birefringent. We propose a scheme that can be implemented at the planned FCC-ee, to measure the nonlinear effect of vacuum birefringence in electrodynamics arising from QED corrections. Our scheme employs a pulsed laser to create Compton backscattered photons off a high energy electron beam, with the FCC-ee as a particularly interesting example. These photons will pass through a strong static magnetic field, which changes the state of polarization of the radiation - an effect proportional to the photon energy. This change will be measured by the use of an aligned single-crystal, where a large difference in the pair production cross-sections can be achieved. In the proposed experimental setup the birefringence effect gives rise to a difference in the number of pairs created in the analyzing crystal, stemming from the fact that the initial laser light has a varying st...

  3. Operation of FCC with mixtures of regenerated and deactivated catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Spretz, R.; Sedran, U. [INCAPE, FIQ, UNL - CONICET, Instituto de Investigaciones en Catalisis y Petroquimica, Santiago del Estero 2654, 3000 Santa Fe (Argentina)

    2001-07-13

    The operation of FCC with mixtures of coked and regenerated catalyst was studied with a riser simulator reactor on two equilibrium catalysts at 550C. The coked catalysts maintain an activity level that enables them to be used in the mixtures. The catalytic performances of the regenerated catalysts were used as references against which the behaviors of 25:75 and 50:50 (coked:regenerated) mixtures were compared. It was observed that overall catoil has to be increased to maintain conversion. While the yields of gases, gasoline and LCO showed to be independent of the operative mode, changes were observed in the selectivity to light olefins C4-C6 that are mainly due to changes in the yields of the isoparaffins in the groups. In turn, these changes could be the consequence of the resulting density of paired acid sites in the zeolite components on hydrogen transfer reactions, due to the contributions by the coked and regenerated portions of catalysts. Coke yields in mixtures of coked and regenerated catalysts are not higher, which would allow increasing catalyst circulation without impacting on heat balance. The particularities of this new operation of FCC are very dependent on catalyst properties.

  4. Iron Contamination Mechanism and Reaction Performance Research on FCC Catalyst

    Directory of Open Access Journals (Sweden)

    Zhaoyong Liu

    2015-01-01

    Full Text Available FCC (Fluid Catalytic Cracking catalyst iron poisoning would not only influence units’ product slate; when the poisoning is serious, it could also jeopardize FCC catalysts’ fluidization in reaction-regeneration system and further cause bad influences on units’ stable operation. Under catalytic cracking reaction conditions, large amount of iron nanonodules is formed on the seriously iron contaminated catalyst due to exothermic reaction. These nodules intensify the attrition between catalyst particles and generate plenty of fines which severely influence units’ smooth running. A dense layer could be formed on the catalysts’ surface after iron contamination and the dense layer stops reactants to diffuse to inner structures of catalyst. This causes extremely negative effects on catalyst’s heavy oil conversion ability and could greatly cut down gasoline yield while increasing yields of dry gas, coke, and slurry largely. Research shows that catalyst’s reaction performance would be severely deteriorated when iron content in E-cat (equilibrium catalyst exceeds 8000 μg/g.

  5. Multivariable Control and Online State Estimation of an FCC Unit

    Directory of Open Access Journals (Sweden)

    A. T. Boum

    2015-10-01

    Full Text Available The purpose of this paper is to realize multivariable control , tuning and online state estimation of some parameters of the FCC unit . We implemented two control structures with the manipulated variables being the air inlet flow rate in the regenerator, the regenerated catalyst flow rate and the feed flow rate and, the controlled variable being the temperatures in the riser and in the densed bed of the regenerator. A novel four transfer function is built and used for controllability studies. Hard constraints are imposed with respect to the manipulated variables. Simulation results show that the configuration made of two inputs and two outputs is more easy to tune for control purposes. Althought there are important dynamic interactions between the components of the FCC and important nonlinearities, linear model predictive control is able to maintain a smooth multivariable control of the plant, while taking into account the different constraints. Tuning strategy is implemented to improve the tracking of the set point. Online state estimation is carried out with the use of the extended Kalman filter. The estimation gives results that can be used for monitoring purposes even in the presence of model mismatch.

  6. Ru Nanoframes with an fcc Structure and Enhanced Catalytic Properties.

    Science.gov (United States)

    Ye, Haihang; Wang, Qingxiao; Catalano, Massimo; Lu, Ning; Vermeylen, Joseph; Kim, Moon J; Liu, Yuzi; Sun, Yugang; Xia, Xiaohu

    2016-04-13

    Noble-metal nanoframes are of great interest to many applications due to their unique open structures. Among various noble metals, Ru has never been made into nanoframes. In this study, we report for the first time an effective method based on seeded growth and chemical etching for the facile synthesis of Ru nanoframes with high purity. The essence of this approach is to induce the preferential growth of Ru on the corners and edges of Pd truncated octahedra as the seeds by kinetic control. The resultant Pd-Ru core-frame octahedra could be easily converted to Ru octahedral nanoframes of ∼2 nm in thickness by selectively removing the Pd cores through chemical etching. Most importantly, in this approach the face-centered cubic (fcc) crystal structure of Pd seeds was faithfully replicated by Ru that usually takes an hcp structure. The fcc Ru nanoframes showed higher catalytic activities toward the reduction of p-nitrophenol by NaBH4 and the dehydrogenation of ammonia borane compared with hcp Ru nanowires with roughly the same thickness.

  7. Precision Electroweak measurements at the FCC-ee

    CERN Document Server

    Dam, Mogens

    2016-01-01

    Because of a luminosity of up to five orders of magnitude larger than at LEP, electroweak precision measurements at the FCC-ee -- the Future Circular Collider with electron-positron beams -- would provide improvements by orders of magnitude over the present status and constitute a broad search for the existence of new, weakly interacting particles up to very high energy scales. The FCC-ee will address centre-of-mass energies ranging from below the Z pole to the $\\mathrm{t\\bar{t}}$ threshold and above. At energies around the Z pole, the Z-boson mass and width can be measured to better than 100 keV each. Asymmetry measurements at the Z pole allow improvements in the determination of the weak mixing angle by at least a factor 30 to $\\delta\\sin^2\\theta\\mathrm{_W^{eff}}\\simeq 6\\times 10^{-6}$. A determination of the electromagnetic coupling constant at the Z energy scale, $\\alpha_\\mathrm{QED}(m_\\mathrm{Z}^2)$, to a relative precision of $3\\times 10^{-5}$ can be obtained via measurement of the forward-backward asym...

  8. First Principles on Spinodal Decomposition of Fcc-Cr1-xSixN%第一性原理计算Fcc-Cr1-xSixN的调幅分解

    Institute of Scientific and Technical Information of China (English)

    高巍; 谢飞

    2010-01-01

    基于通过第一性原理计算方法,计算了三元固溶体Fcc-Cr1-xSixN总能,在此基础上计算了其分离能和调幅分解线.结果说明,Fcc-Cr1-xSixN是亚稳相,能够经调幅分解机制分解为Fcc-CrN和Fcc-SiN.组元相形成的应变能小于分离能,不会抑制Fcc-Cr1-xSixN的调幅分解.Fcc-Cr1-xSixN的Si含量为渗透阈值时,不会发生调幅分解.Fcc-Cr1-xSixN可能经调幅分解生成Fcc-SiN.

  9. Cellular Phone Towers - TOWERS_CELLUAR_FCC_ULS_IN: Cellular Towers in Indiana (Bernardin, Lochmueller & Associates, Derived from FCC ULS, Point Shapefile)

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This dataset is a point shapefile of licensed cellular towers downloaded as part of the FCC ULS database of cellular towers in Indiana. The ground condition of this...

  10. On Campus Web-Monitoring Rules, Colleges and the FCC Have a Bad Connection

    Science.gov (United States)

    Hartle, Terry W.

    2006-01-01

    A regulation issued by the US Federal Communications Commission (FCC) requires facilities-based Internet services providers who operate their own equipment, including colleges, to make their Internet systems compliant with a statute known as the Communications Assistance for Law Enforcement Act (Calea) by April 2007. However, the FCC does not…

  11. The FCC, The Coverage Principle of the Fairness Doctrine and the First Amendment.

    Science.gov (United States)

    Chamberlin, Bill F.

    This review of the history of the coverage principle developed by the Federal Communications Commission (FCC) concludes that government regulation of mass media program content can be dangerous and that the coverage principle needs to be abolished. The first section of the report discusses the FCC's interpretation of the 1934 Communications Act…

  12. Inequities in Mass Communication Law: The FCC's Application of the Duopoly Rule to Public Broadcasting.

    Science.gov (United States)

    Avery, Robert K.

    A three-part petition was filed in December 1974 with the Federal Communications Commission (FCC) which presented the first serious threat to public broadcasters' exemption from the FCC's multiple-ownership rules. The petition requested a revision of the rules that permit multiple ownership of noncommercial educational stations within a single…

  13. 47 CFR Appendix A to Subpart A of... - Locations Where GMRS Is Regulated by the FCC

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Locations Where GMRS Is Regulated by the FCC A Appendix A to Subpart A of Part 95 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY.... A, App. A Appendix A to Subpart A of Part 95—Locations Where GMRS Is Regulated by the FCC In...

  14. Can the Lennard-Jones solid be expected to be fcc?

    NARCIS (Netherlands)

    Waal, van de Benjamin W.

    1991-01-01

    The structure of the Lennard-Jones solid, obtained by molecular-dynamics simulation of crystallization in the supercooled liquid, may be fcc, although the hcp structure is energetically more favorable. This could derive from the cubic symmetry of the fcc lattice, allowing lattice defects that are no

  15. Theory of alkali-metal-induced reconstructions of fcc(100) surfaces

    DEFF Research Database (Denmark)

    Christensen, Ole Bøssing; Jacobsen, Karsten Wedel

    1992-01-01

    Calculations of missing-row reconstruction energies of the fcc(100) surfaces of the metals Al, Ni, Pd, Pt, Cu, Ag, and Au have been performed with the effective-medium theory with and without the presence of a potassium overlayer. It is shown that the tendency to reconstruct in the presence......-metal-induced reconstruction of fcc(110) surfaces are pointed out....

  16. 47 CFR 64.1110 - State notification of election to administer FCC rules.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false State notification of election to administer FCC rules. 64.1110 Section 64.1110 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED... Telecommunications Service Providers § 64.1110 State notification of election to administer FCC rules. (a)...

  17. 47 CFR 2.1076 - FCC inspection and submission of equipment for testing.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false FCC inspection and submission of equipment for testing. 2.1076 Section 2.1076 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY... Declaration of Conformity § 2.1076 FCC inspection and submission of equipment for testing. (a)...

  18. 78 FR 34099 - FCC Extends Pleading Cycle for Indecency Cases Policy

    Science.gov (United States)

    2013-06-06

    ... COMMISSION FCC Extends Pleading Cycle for Indecency Cases Policy AGENCY: Federal Communications Commission.... until 11:30 a.m. on Friday at the FCC Reference Information Center, Portals II, Room CY- A257, 445 12th...-B402, Washington, DC 20554, telephone (800) 378- 3160, facsimile (202) 488-5563, email...

  19. 47 CFR 2.956 - FCC inspection and submission of equipment for testing.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false FCC inspection and submission of equipment for testing. 2.956 Section 2.956 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY... Verification § 2.956 FCC inspection and submission of equipment for testing. (a) Each responsible party...

  20. 76 FR 69738 - Revised 2011 Annual Telecommunications Reporting Worksheet (FCC Form 499-A) and Accompanying...

    Science.gov (United States)

    2011-11-09

    ... COMMISSION Revised 2011 Annual Telecommunications Reporting Worksheet (FCC Form 499-A) and Accompanying... Competition Bureau released the revised Telecommunications Reporting Worksheet (FCC Form 499-A) and... Competition Bureau, Telecommunications Access Policy Division, at (202) 418-7400 or via the Internet...

  1. 78 FR 49480 - Proposed Information Collection; Comment Request; NTIA/FCC Web-based Frequency Coordination System

    Science.gov (United States)

    2013-08-14

    ...; NTIA/FCC Web- based Frequency Coordination System AGENCY: National Telecommunications and Information... coordination will be required by the Federal Communications Commission (FCC) and NTIA. III. Data OMB Control...

  2. FCC Based Lepton-Hadron and Photon-Hadron Colliders: Luminosity and Physics

    CERN Document Server

    Acar, Y C; Beser, S; Karadeniz, H; Kaya, U; Oner, B B; Sultansoy, S

    2016-01-01

    Construction of future electron-positron colliders (or dedicated electron linac) and muon colliders (or dedicated muon ring) tangential to Future Circular Collider (FCC) will give opportunity to utilize highest energy proton and nucleus beams for lepton-hadron and photon-hadron collisions. Luminosity values of FCC based ep, \\mup, eA, \\muA, \\gammap and \\gammaA colliders are estimated. Multi-TeV center of mass energy ep colliders based on the FCC and linear colliders (LC) are considered in detail. Parameters of upgraded versions of the FCC proton beam are determined to optimize luminosity of electron-proton collisions keeping beam-beam effects in mind. Numerical calculations are performed using a currently being developed collision point simulator. It is shown that L_{ep}\\sim10^{32}\\,cm^{-2}s^{-1} can be achieved with LHeC-like upgrade of the FCC parameters.

  3. Solution based synthesis of simple fcc Si nano-crystals under ambient conditions.

    Science.gov (United States)

    Balcı, Mustafa H; Sæterli, Ragnhild; Maria, Jerome; Lindgren, Mikael; Holmestad, Randi; Grande, Tor; Einarsrud, Mari-Ann

    2013-02-28

    We demonstrate for the first time that simple face-centered cubic (fcc) silicon nano-crystals can be produced by a solution based bottom-up synthesis route under ambient conditions. Simple fcc Si nano-crystals (2-7 nm) were prepared at room temperature by using sodium cyclopentadienide as a reducing agent for silicon tetrachloride. Photoluminescence emission at 550 nm was observed for the fcc silicon nano-crystals upon excitation at 340 nm, indicating that fcc Si nano-crystals were exhibiting direct bandgap like semiconductor properties with very fast radiative recombination rates. The new synthesis route makes possible the production and study of simple fcc polymorphs of Si nano-crystals with an easy alteration of surface termination groups.

  4. Temperature-pressure-induced solid-solid to reorientation in FCC metallic nanowire: a molecular dynamic study.

    Science.gov (United States)

    Sutrakar, Vijay Kumar; Roy Mahapatra, D; Pillai, A C R

    2012-01-11

    Atomistic simulation of initial oriented FCC Cu nanowires shows a novel coupled temperature-pressure dependent reorientation from to phase. A temperature-pressure-induced solid-solid to reorientation diagram is generated for Cu nanowire with varying cross-sectional sizes. A critical pressure is reported for Cu nanowires with varying cross-sectional sizes, above which an initial oriented nanowire shows temperature independent reorientation into the phase. The effect of surface stresses on the to reorientation is also studied. The results indicate that above a critical cross-sectional size for a given temperature-pressure, to reorientation is not possible. It is also reported here that for a given applied pressure, an increase in temperature is required for the to reorientation with increasing cross-sectional size of the nanowire. The temperature-pressure-induced solid-solid to reorientation diagram reported in the present paper could further be used as guidelines for controlling the reorientations/shape memory in nano-scale applications of FCC metallic nanowires.

  5. 47 CFR Appendix 1 to Part 97 - Places Where the Amateur Service is Regulated by the FCC

    Science.gov (United States)

    2010-10-01

    ... by the FCC 1 Appendix 1 to Part 97 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED... the Amateur Service is Regulated by the FCC In ITU Region 2, the amateur service is regulated by the FCC within the territorial limits of the 50 United States, District of Columbia, Caribbean...

  6. 78 FR 23563 - FCC Reduces Backlog of Broadcast Indecency Complaints by 70% (More Than One Million Complaints...

    Science.gov (United States)

    2013-04-19

    ... COMMISSION FCC Reduces Backlog of Broadcast Indecency Complaints by 70% (More Than One Million Complaints...., Monday through Thursday or from 8 a.m. until 11:30 a.m. on Friday at the FCC Reference Information Center... (202) 488-5563, email FCC@BCPIWEB.com , or you may contact BCPI via its Web site,...

  7. Isomorphic phase transformation in shocked Cerium using molecular dynamics

    OpenAIRE

    Germann T.C.; Chen S.-P.; Dupont V.

    2011-01-01

    Cerium (Ce) undergoes a significant (∼16%) volume collapse associated with an isomorphic fcc-fcc phase transformation when subject to compressive loading. We present here a new Embedded Atom Method (EAM) potential for Cerium that models two minima for the two fcc phases. We show results from its use in Molecular Dynamics (MD) simulations of Ce samples subjected to shocks with pressures ranging from 0.5 to 25 GPa. A split wave structure is observed, with an elastic precursor followed by a plas...

  8. Lattice mechanical properties of some fcc f-shell metals

    Indian Academy of Sciences (India)

    J K Baria; A R Jani

    2003-06-01

    A pseudopotential depending on an effective core radius is proposed to study the binding energy, equation of state, ion–ion interaction, phonon dispersion curves (q-space and r-space analysis), mode Gr¨uneisen parameters and dynamical elastic constants of some fcc f-shell metals La, Yb, Ce and Th. The contribution of the s-like electrons is calculated in the second-order perturbation theory for the potential while d- and f-like electron is taken into account by introducing repulsive short-range Born–Mayer term. The parameter of the potential is evaluated by zero pressure condition. An excellent agreement between theoretical investigations and experimental findings is achieved which confirms the present formalism.

  9. The FCC-ee Interaction Region Magnet Design

    CERN Document Server

    Koratzinos, M; Bogomyagkov, A; Sinyatkin, S; Benedikt, M; Holzer, B; van Nugteren, J; Zimmermann, F; Oide, K

    2016-01-01

    The design of the region close to the interaction point of the FCC-ee experiments is especially challenging. The beams collide at an angle (+-15 mrad) in the high-field region of the detector solenoid. Moreover, the very low vertical beta_y* of the machine necessitates that the final focusing quadrupoles have a distance from the IP (L*) of around 2 m and therefore are inside the main detector solenoid. The beams should be screened from the effect of the detector magnetic field, and the emittance blow-up due to vertical dispersion in the interaction region should be minimized, while leaving enough space for detector components. Crosstalk between the two final focus quadrupoles, only about 6 cm apart at the tip, should also be minimized.

  10. Electrical conductance through nanocontacts between fcc(100) electrodes of gold

    Energy Technology Data Exchange (ETDEWEB)

    Koudela, Daniela; Lopez-Acevedo, Olga; Walter, Michael [Department of Physics, Nanoscience Center, P.O. Box 35, FIN-40014 University of Jyvaeskylae (Finland); Haekkinen, Hannu [Department of Physics, Nanoscience Center, P.O. Box 35, FIN-40014 University of Jyvaeskylae (Finland); Department of Chemistry, P.O. Box 35, FIN-40014 University of Jyvaeskylae (Finland)

    2008-07-01

    Both experimental and theoretical work has been done to explain conductance curves for metal nanowires, giving presently a good model that allows to explain experimental results microscopically. For one atom contacts it has moreover been shown, theoretically and experimentally, a strong relation between the number of valence orbitals of the single atom and the maximum value of the conductance that can be obtained. We have studied Au nanowires of different lengths connected to fcc(100) tips corresponding to possible configurations in the elongation process. For those systems we have calculated the self-consistent potential obtained with Density Functional Theory and used it to calculate the conductance using the recursion-transfer-matrix method. Our results show that though gold has formally only one valence electron (6s), for wires shorter than 3 atoms there are 3 (partially) open eigenmodes.

  11. Diffusion and segregation of niobium in fcc-nickel.

    Science.gov (United States)

    Connétable, Damien; Ter-Ovanessian, Benoît; Andrieu, Éric

    2012-03-01

    Niobium is one of the major alloying elements, among the refractory elements, contributing to the strengthening of superalloys. Consequently, data about its behavior and its migration mechanism in fcc-Ni are essential knowledge to understand and control the strengthening in such alloys. We present in this work Nb interactions, solubility and diffusion in Ni performed by using the GGA approximation of the density functional theory. The substituted site is found to be the most favorable configuration in comparison to the tetrahedral and octahedral sites. The effect of temperature on solubility is discussed taking into account the thermal expansion of the lattice parameter and the vibrational contribution. Its diffusion mechanism is also discussed and compared to the literature. We finally discuss the segregation of Nb atoms on a Σ(5)-(012) symmetric tilt grain boundary.

  12. Effect of the Vibrational Modes on the Ag-Cu Phase Diagram

    Institute of Scientific and Technical Information of China (English)

    DUAN Su-Qing; ZHAO Xian-Geng; LIU Shao-Jun; MA Ben-Kun

    2000-01-01

    We calculated the vibrational free energies of the selected ordered compounds in the Ag-Cu system by using two kinds of methods: (1) calculating the phonon dispersion and density of states and the consequently vibrational free energies by using the method of ab initio inverted interatomic potentials and dynamic matrix; (2) the vibrational free energies determined by a Debye-Griineisen approximation. The Ag-Cu phase diagram is calculated by the cluster variation method. The results show that the solubility at Ag-rich end of the calculated phase diagram considering vibrational modes by using the first method is in better agreement with the experimental.

  13. The enthalpy change of the hcp {yields} fcc martensitic transformation in Fe-Mn-Co alloys: composition dependence and thermal cycling effects

    Energy Technology Data Exchange (ETDEWEB)

    Marinelli, P.; Fernandez Guillermet, A.; Sade, M

    2004-05-25

    Extending a recent calorimetric study of the Fe-Mn system the enthalpy change associated with the fcc{yields}hcp martensitic transformation in the Fe-Mn-Co system has been determined in alloys with 13{<=}at.% Mn{<=}30 and up to 9 at.% Co. The heat effect has been measured by differential scanning calorimetry, whereas the fraction of material that transformed martensitically was determined by combining a dilatometric technique with the known molar volume versus composition relations. A detailed description of the various experimental and data processing procedures is reported. The enthalpy change is discussed as a function of composition and of the number of thermal cycles of transformation and retransformation. The picture of the energetics of the fcc{yields}hcp martensitic transformation emerging from the present study should be useful in future attempts to model the thermodynamics and phase stability relations in the Fe-Mn-Co system.

  14. Separating the strengthening phase in nickel-cobalt alloys doped with tantalum

    Science.gov (United States)

    Shaipov, R. Kh.; Kerimov, E. Yu.; Slyusarenko, E. M.

    2017-02-01

    The hardness values of monophasic (fcc solid solution) and biphasic (fcc solid solution and separated phase) nickel-cobalt alloys doped with tantalum are determined using the Vickers method. Based on the resulting data, a composition-structure-hardness diagram is devised for the Co-Ni-Ta system.

  15. On Groups Whose Proper Quotients Are FCc-Groups with the Maximal Condition%其真商群为满足极大条件的FCc-群的群

    Institute of Scientific and Technical Information of China (English)

    张志让; 邢世奇

    2012-01-01

    如果FCc-群满足极大条件,那么称之为(FCc) max群;如果群G的所有真商群都是(FCc) max-群,但是G本身不是(FCc) max-群,那么称群G为外(FCc)-max群.主要利用外FNc-群的结果,给出外(FCc)max群的结构描述,同时还推广了群的上下中心列的有限性条件.%A group is an (FCc )max-group if it is an FCc-group with the maximal condition. Group G is said to be a just non-(FCc )max-group if all of its proper quotients are (FCc )max-groups, but G itself is not. The main purpose of this article is to give a description of the structure of just non-(FCc )max-groups by making use of the results of just non-FNc-groups. Hall on finiteness conditions of upper and lower central series of groups is given.

  16. 催化裂化汽提技术的发展%THE DEVELOPMENT OF FCC STRIPPING TECHNOLOGY

    Institute of Scientific and Technical Information of China (English)

    张振千

    2003-01-01

    This article briefly describes the major patents domestic and the abroad, and the current situation and achievements of FCC stripping technology in China. The developing trend of FCC stripping technology is presented, including further developments of FCC stripper to improve unit performance, combination of the stripper and pre-stripper within disengager to form a complete high-efficiency FCC stripping system. In addition to high efficiency, simple structure and easiness of installation and maintenance for a new FCC stripper are all of consideration.

  17. Controlled FCC/on-top binding of H/Pt(111) using surface stress

    Science.gov (United States)

    Shuttleworth, I. G.

    2016-08-01

    The preferred binding site of H/Pt(111) has been shown to be change from the on-top to FCC as the Pt(111) surface goes approximately from a state of compressive to tensile strain. A chemical analysis of the system has shown that for both FCC and on-top bound cases the H ssbnd Pt s and H ssbnd Pt d interactions have a similar importance in determining the preferred binding position. It has been seen that FCC-bound H forms a distinct state below the Pt d-band, whereas the on-top bound H does not.

  18. Study on Metal-Passivating Elements in FCC Operation and Their Migration

    Institute of Scientific and Technical Information of China (English)

    Liu Xiaodong; Cui Yan; Zhang Ruichi; Chen Zupi

    2004-01-01

    Elements including P, Sb, Ce, La, B, Sn, Ti, Bi and Mg that could passivate Ni and V were studied on their migration on FCC catalysts and carriers under simulated commercial FCC operating conditions.Test results had shown that P, Sb, B and Sn compounds exhibited migration activity. The effects of temperature, fluidizing medium and contact time on migration of antimony compounds were investigated,and the mechanism regarding antimony migration was proposed. Meanwhile, it was disclosed that Ni on catalyst could stimulate Sb contained in the metal passivator to move onto FCC catalyst in tandem with the interaction between nickel and antimony.

  19. Nonlinearities in composition dependence of structure parameters and magnetic properties of nanocrystalline fcc/bcc-mixed Co-Ni-Fe thin films

    NARCIS (Netherlands)

    Chechenin, N. G.; Khomenko, E. V.; Vainchtein, D. I.; De Hosson, J. Th. M.

    2008-01-01

    In this report, the nonlinearities are analyzed in fcc-to-bcc (fcc/bcc) population ratio, lattice parameters (a(exp)(fcc)/a(ideal)(fcc) and a(exp)(bcc)/a(ideal)(bcc)) and saturation magnetization (I(S)(obs)/I(S)(a)) of the electrodeposited thin Co-Fe-Ni films as a function of average number of elect

  20. Development of New Generation Catalysts for Selective Hydrodesulfurization of FCC Naphtha

    Institute of Scientific and Technical Information of China (English)

    Chu Yang; Li Mingfeng; Li Huifeng; Qu Jinhua; Nie Hong; Li Dadong

    2009-01-01

    The influence of active metal components of catalyst, additives and catalyst preparation method on the reactiv-ity of catalyst for selective hydrodesulfurization (HDS) of FCC naphtha was investigated, and the RSDS-21 catalyst with high HDS performance and the RSDS-22 catalyst with high selectivity were developed by RIPP. The composite loading of a new series of catalysts for selective HDS of FCC gasoline has demonstrated excellent desulfurization activity and selectivity and can under conventional hydrotreating conditions manufacture clean gasoline product meeting the national Ⅳ emission standard and the Euro Ⅴ emission standard with less loss in antiknock index. The finalized new series of FCC catalysts upon being adopted for selective HDS of FCC naphtha have good adaptability to different feedstocks along with good stability.

  1. Metastable fcc-Fe film epitaxially grown on Cu(100) single-crystal underlayer

    Science.gov (United States)

    Ohtake, Mitsuru; Shimamoto, Kohei; Futamoto, Masaaki

    2013-05-01

    Fe film of 40 nm thickness is prepared on fcc-Cu(100) single-crystal underlayer at room temperature by ultra-high vacuum molecular beam epitaxy. The film growth and the detailed structure are investigated by reflection high-energy electron diffraction, cross-sectional high-resolution transmission electron microscopy (HR-TEM), and x-ray diffraction (XRD). An Fe single-crystal with metastable fcc structure nucleates on the underlayer. The HR-TEM shows that fcc lattice is formed from the Fe/Cu interface up to the film surface. A large number of misfit dislocations are introduced around the Fe/Cu interface due to an accommodation of lattice mismatch. Dislocations exist up to the film near surface. The lattice constant is estimated by XRD to be a = 0.3607 nm. The film shows a ferromagnetic property, which reflects the property of fcc-Fe crystal with high-spin ferromagnetic state.

  2. Workshop summary, future prospects and FCC-ee impact on $\\alpha_s$

    CERN Document Server

    d'Enterria, David

    2015-01-01

    The workshop on “High-precision α s measurements from LHC to FCC-ee” –organized in the con- text of the preparation of the Future Circular Collider (FCC) Conceptual Design Report, within the FCC-e + e − “QCD and photon-photon” physics working group activities– discussed the latest advances in the measurement of the strong interaction coupling α s . The meeting brought together leading experts in the field to explore in depth recent theoretical and experimental developments on the determination of α s , new ways to measure this coupling in lepton-lepton, lepton-hadron and hadron-hadron collisions, and in particular the improvements expected at the proposed Future Circular Collider e + e − (FCC-ee) facility.

  3. Relative stability of the FCC and HCP polymorphs with interacting polymers.

    Science.gov (United States)

    Mahynski, Nathan A; Kumar, Sanat K; Panagiotopoulos, Athanassios Z

    2015-01-14

    Recent work [Mahynski et al., Nat. Commun., 2014, 5, 4472] has demonstrated that the addition of long linear homopolymers thermodynamically biases crystallizing hard-sphere colloids to produce the hexagonal close-packed (HCP) polymorph over the closely related face-centered cubic (FCC) structure when the polymers and colloids are purely repulsive. In this report, we investigate the effects of thermal interactions on each crystal polymorph to explore the possibility of stabilizing the FCC crystal structure over the HCP. We find that the HCP polymorph remains at least as stable as its FCC counterpart across the entire range of interactions we explored, where interactions were quantified by the reduced second virial coefficient, -1.50 0, its tetrahedral voids produce a similar effect when B FCC crystals are elusive in these binary mixtures.

  4. The FCC Flue Gas SOx Transfer Additive RFS Developed by RIPP

    Institute of Scientific and Technical Information of China (English)

    Chen Beiyan; Jiang Wenbin; Song Haitao; Shen Ningyuan; Tian Huiping; He Mingyuan

    2007-01-01

    The present paper introduces the development of FCC flue gas SOx transfer additives by RIPP with a brief discussion of SOx transfer mechanism. The second-generation SOx transfer additives of the RFS series are RIPP's proprietary additives with significantly improved performances. The results of commercial tests indicate that the RFS additive can effectively control SOx emission of the FCC regenerator while maintaining product yields and product quality when the additive is used in a proper concentration range.

  5. Growth and micromagnetism of self-assembled epitaxial fcc(111) cobalt dots.

    Science.gov (United States)

    Fruchart, O; Masseboeuf, A; Toussaint, J C; Bayle-Guillemaud, P

    2013-12-11

    We develop the self-assembly of epitaxial submicrometer-sized face-centered-cubic (fcc) Co(111) dots using pulsed laser deposition. The dots display atomically flat facets, from which the ratios of surface and interface energies for fcc Co are deduced. Zero-field magnetic structures are investigated with magnetic force and Lorentz microscopies, revealing vortex-based flux-closure patterns. A good agreement is found with micromagnetic simulations.

  6. Main changes to LHC layout for reuse as FCC-hh High Energy Booster

    CERN Document Server

    AUTHOR|(SzGeCERN)396044; Wolfgang Bartmann; Werner Herr; Philippe Lebrun; Attilio Milanese

    2015-01-01

    Reuse of the LHC is one option being investigated for a High Energy Booster for injection of 3.3 TeV protons (and heavy ions at equivalent rigidity) into the proposed 100 TeV centre of mass FCC-hh collider. In this note the major changes required to the LHC layout are listed, assuming beam transfer to the FCC collider is required from both LHC Points 1 and 8.

  7. Structural and magnetic studies of fcc Fe films with self-organized lateral modulation on striped Cu(110)-O(2x1) substrates.

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.

    1998-09-21

    Fcc Fe wedges of 0-12 monolayer (ML) were grown by means of molecular beam epitaxy onto a novel substrate: flat Cu(110) with an oxygen-induced, long-range ordered striped phase, and studied in-situ with medium energy electron diffraction (MEED) and the surface magneto-optical Kerr effect (SMOKE). In contrast to Fe growth on either clean or oxygen-saturated Cu(110), the films on the striped substrates retain a layer-by-layer growth mode up to 6-7 ML and are fcc at least up to 12 ML. In addition, satellite peaks were observed on both sides of the MEED (0,0) streak, indicating a long-range-ordered lateral modulation of the Fe surface. We postulate that the Fe films grow conformally onto the original striped substrate. SMOKE studies show that these fcc Fe wedges are ferromagnetic with an easy axis along the original stripes for Fe thickness > 4ML and a remnant magnetization that increases linearly with thickness beyond 4 ML.

  8. Post-riser Regeneration Technology in FCC Unit

    Institute of Scientific and Technical Information of China (English)

    Liu Xiancheng; Lu Chunxi; Shi Mingxian

    2007-01-01

    In our present work,a post-riser regeneration technology (PRRT) for fluid catalytic cracking (FCC) units was developed to deal with increasingly heavier feedstock and hereby the larger amount of coke deposited on the catalyst particles during reaction.This technology can make full use of the advantages of riser regenerator,such as high coke-burning efficiency and low residual carbon,and at the same time overcome its disadvantages,such as difficulty in starting combustion.The average particles concentration on the cross section of the system was studied on a large scale cold model experimental set-up.Also a necessary software was developed by combining the hydrodynamics research results in our work with the coke-burning kinetics model and the heat and mass transfer model developed by previous researchers.The simulation results showed that the PRRT could increase regeneration capability by 16.28%-26.24% over the conventional turbulent fluidized bed regenerator under the similar operation conditions,and that the residual carbon could be kept below 0.1 wt%.

  9. Precision Natural SUSY at CEPC, FCC-ee, and ILC

    CERN Document Server

    Fan, JiJi; Wang, Lian-Tao

    2014-01-01

    Testing the idea of naturalness is and will continue to be one of the most important goals of high energy physics experiments. It will play a central role in the physics program of future colliders. In this paper, we present projections of the reach of natural SUSY at future lepton colliders: CEPC, FCC-ee and ILC. We focus on the observables which give the strongest reach, the electroweak precision observables (for left-handed stops), and Higgs to gluon and photon decay rates (for both left- and right-handed stops). There is a "blind spot" when the stop mixing parameter Xt is approximately equal to the average stop mass. We argue that in natural scenarios, bounds on the heavy Higgs bosons from tree-level mixing effects that modify the bottom Yukawa coupling together with bounds from b to s gamma play a complementary role in probing the blind spot region. For specific natural SUSY scenarios such as folded SUSY in which the top partners do not carry Standard Model color charges, electroweak precision observable...

  10. Scenario for Precision Beam Energy Calibration in FCC-ee

    CERN Document Server

    Koop, I A

    2015-01-01

    The resonance depolarization method was very successfully used in the experiments at LEP, where the mass of the Z-boson was determined with the relative uncertainty [1, 2]. In the future FCC-ee circular electron-positron collider the luminosity at Z-peak (beam energy 45.5 GeV) is expected be 4-5 orders of magnitude higher and one goal is to perform the same experiments as at LEP, but with much greater accuracy, approaching the level of [3]. Obviously this can be done only by measuring the spin precession frequency. But there are many problems which still need to be solved on the way towards a complete design. The first one: the self-polarization takes too long a time. The Sokolov-Ternov polarization time is about 250 hours at Z-peak. One approach is to install the special field-asymmetric polarizing wigglers to make the self-polarization time much shorter [4, 5] and to utilize only few percent of the polarization degree to measure the resonance spin precession frequency. But these very strong wigglers substan...

  11. Scaling Laws and Critical Properties for fcc and hcp Metals.

    Science.gov (United States)

    Desgranges, Caroline; Widhalm, Leanna; Delhommelle, Jerome

    2016-06-16

    The determination of the critical parameters of metals has remained particularly challenging both experimentally, because of the very large temperatures involved, and theoretically, because of the many-body interactions that take place in metals. Moreover, experiments have shown that these systems exhibit an unusually strong asymmetry of their binodal. Recent theoretical work has led to new similarity laws, based on the calculation of the Zeno line and of the underlying Boyle parameters, which provided results for the critical properties of atomic and molecular systems in excellent agreement with experiments. Using the recently developed expanded Wang-Landau (EWL) simulation method, we evaluate the grand-canonical partition function, over a wide range of conditions, for 11 fcc and hcp metals (Ag, Al, Au, Be, Cu, Ir, Ni, Pb, Pd, Pt, and Rh), modeled with a many-body interaction potential. This allows us to calculate the binodal, Zeno line, and Boyle parameters and, in turn, obtain the critical properties for these systems. We also propose two scaling laws for the enthalpy and entropy of vaporization, and identify critical exponents of 0.4 and 1.22 for these two laws, respectively.

  12. Microcalorimetry of oxygen adsorption on fcc Co{110}.

    Science.gov (United States)

    Liao, Kristine; Fiorin, Vittorio; Jenkins, Stephen J; King, David A

    2012-05-28

    The coverage dependent heats of adsorption and sticking probabilities for oxygen on fcc Co{110} have been measured at 300 K using single crystal adsorption calorimetry (SCAC). Initial adsorption is consistent with dissociative chemisorption at low coverage followed by oxide formation above 0.6 ML coverage. The initial heat of adsorption of 633 kJ mol(-1) is similar to heat values calorimetrically measured on other ferromagnetic metal surfaces, such as nickel and iron. As the coverage increases, the heat of adsorption and sticking probability drop very rapidly up to the onset of oxidation. As already observed for other oxygen-metal surface systems, strong lateral adatom repulsions are responsible for the transition from the chemisorption regime to oxide film formation at higher coverage. The heat of oxide formation at the onset is 475 kJ mol(-1), which is consistent with the formation of CoO crystallites. The oxide film formation is discussed in terms of nucleation and island growth, and the Mott-Cabrera mechanisms, the latter being evidenced by the relatively constant heat of adsorption and sticking probability in contrast to the nickel and iron oxidation cases.

  13. Phase diagram of power law and Lennard-Jones systems: Crystal phases

    Energy Technology Data Exchange (ETDEWEB)

    Travesset, Alex [Ames Laboratory

    2014-10-28

    An extensive characterization of the low temperature phase diagram of particles interacting with power law or Lennard-Jones potentials is provided from Lattice Dynamical Theory. For power law systems, only two lattice structures are stable for certain values of the exponent (or softness) (A15, body centered cube (bcc)) and two more (face centered cubic (fcc), hexagonal close packed (hcp)) are always stable. Among them, only the fcc and bcc are equilibrium states. For Lennard-Jones systems, the equilibrium states are either hcp or fcc, with a coexistence curve in pressure and temperature that shows reentrant behavior. The hcp solid never coexists with the liquid. In all cases analyzed, for both power law and Lennard-Jones potentials, the fcc crystal has higher entropy than the hcp. The role of anharmonic terms is thoroughly analyzed and a general thermodynamic integration to account for them is proposed.

  14. Lattice dynamics and phase diagram of aluminum at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kudasov, Yu. B., E-mail: yu_kudasov@yahoo.com; Surdin, O. M.; Korshunov, A. S.; Pavlov, V. N. [National Research Nuclear University ' MEPhI,' , Sarov State Institute of Physics and Technology (Russian Federation); Frolova, N. V.; Kuzin, R. S. [Russian Federal Nuclear Center-All-Russian Research Institute of Experimental Physics (Russian Federation)

    2013-10-15

    The dispersion of phonons in the fcc, hcp, and bcc phases of aluminum is calculated at ultrahigh pressures by the method of small displacements in a supercell. The stability of the phonon subsystem is studied. The thermodynamic characteristics are calculated in the quasi-harmonic approximation, and a phase diagram of aluminum is plotted. As compared to the Debye model, the use of a phonon spectrum calculated in the quasi-harmonic approximation significantly broadens the hcp phase field and strongly shifts the phase boundary between the fcc and bcc phases. The normal isentrope is calculated at megabar pressures. It is shown to intersect the fcc-hcp and hcp-bcc phase boundaries. The sound velocity along the normal isentrope is calculated. It is shown to have a nonmonotonic character.

  15. Long-Lived Metastable bcc Phase during Ordering of Micelles

    Science.gov (United States)

    Bang, Joona; Lodge, Timothy P.

    2005-03-01

    We report a metastable bcc phase that intervenes between a disordered micellar suspension and an fcc crystal in a block copolymer solution. A symmetric poly(styrene-b-isoprene) diblock copolymer in the isoprene-selective solvent squalane at a volume fraction of 0.20 was investigated using small angle x-ray scattering and rheology. Upon heating, the metastable bcc phase nucleates first, and then transforms over the course of hours to the stable fcc phase. At still higher temperatures the fcc phase transforms to an equilibrium bcc phase. The metastability of the bcc phase was confirmed by oscillatory shear and annealing using small angle x-ray scattering. These results constitute an interesting experimental manifestation of Ostwald's step rule, and also support recent theory and simulation results whereby bcc nucleates more readily from a melt of spheres.

  16. 降低FCC汽油烯烃的措施%MEASURES FOR DECREASING OLEFINE OF FCC GASOLINE

    Institute of Scientific and Technical Information of China (English)

    郝代军

    2001-01-01

    The measures for decreasing olefin of FCC gasoline were introduced. Selecting FCC feed stock, improving FCCU process schemes, using FCC catalyst or co-catalyst which have function for decreasing FCC gasoline olefin are the effective measure to decrease olefin of FCC gasoline. Etherification of FCC light gasoline and hydrodesulfurization (HDS) of FCC heave gasoline , or hydrodesulfurization of FCC gasoline are also the effective measures for producing clean gasoline.%介绍了降低催化裂化(FCC)汽油烯烃的几项措施。从FCC技术自身来讲,优化原料结构、改善装置操作条件、选择降烯烃催化剂和使用降烯烃助剂等方法是简单易行的。如洛阳石油化工工程公司开发的LAP降低烯烃助剂可降低烯烃10个百分点,且辛烷值略有提高。另外,对FCC轻汽油进行醚化并对重汽油加氢脱硫,或者FCC汽油全馏分加氢脱硫降烯烃,也是降低FCC汽油烯烃的有效措施。

  17. Unique Bonding Properties of the Au36(SR)24 Nanocluster with FCC-Like Core.

    Science.gov (United States)

    Chevrier, Daniel M; Chatt, Amares; Zhang, Peng; Zeng, Chenjie; Jin, Rongchao

    2013-10-03

    The recent discovery on the total structure of Au36(SR)24, which was converted from biicosahedral Au38(SR)24, represents a surprising finding of a face-centered cubic (FCC)-like core structure in small gold-thiolate nanoclusters. Prior to this finding, the FCC feature was only expected for larger (nano)crystalline gold. Herein, we report results on the unique bonding properties of Au36(SR)24 that are associated with its FCC-like core structure. Temperature-dependent X-ray absorption spectroscopy (XAS) measurements at the Au L3-edge, in association with ab initio calculations, show that the local structure and electronic behavior of Au36(SR)24 are of more molecule-like nature, whereas its icosahedral counterparts such as Au38(SR)24 and Au25(SR)18 are more metal-like. Moreover, site-specific S K-edge XAS studies indicate that the bridging motif for Au36(SR)24 has different bonding behavior from the staple motif from Au38(SR)24. Our findings highlight the important role of "pseudo"-Au4 units within the FCC-like Au28 core in interpreting the bonding properties of Au36(SR)24 and suggest that FCC-like structure in gold thiolate nanoclusters should be treated differently from its bulk counterpart.

  18. Te-centric view of the phase change mechanism in Ge-Sb-Te alloys.

    Science.gov (United States)

    Sen, S; Edwards, T G; Cho, J-Y; Joo, Y-C

    2012-05-11

    The short-range structure of amorphous and fcc Ge1Sb2Te4 and Ge2Sb2Te5 phase-change alloys is investigated using 125Te NMR spectroscopy. Both amorphous and fcc structures consist solely of heteropolar Ge/Sb-Te bonds that may enable rapid displacive phase transformation without the need for extensive atomic rearrangement. The vacancy distribution is random in microcrystalline fcc phases while significant clustering is observed in their nanocrystalline counterparts that may result in the formation of tetrahedrally coordinated Ge atoms in the latter. This structural commonality may further facilitate the kinetics of transformation between amorphous and nanocrystalline fcc phases, a situation relevant for high-density memory storage.

  19. Bulk Nanostructured FCC Steels With Enhanced Radiation Tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xinghang; Hartwig, K. Ted; Allen, Todd; Yang, Yong

    2012-10-27

    The objective of this project is to increase radiation tolerance in austenitic steels through optimization of grain size and grain boundary (GB) characteristics. The focus will be on nanocrystalline austenitic Fe-Cr-Ni alloys with an fcc crystal structure. The long-term goal is to design and develop bulk nanostructured austenitic steels with enhanced void swelling resistance and substantial ductility, and to enhance their creep resistance at elevated temperatures via GB engineering. The combination of grain refinement and grain boundary engineering approaches allows us to tailor the material strength, ductility, and resistance to swelling by 1) changing the sink strength for point defects, 2) by increasing the nucleation barriers for bubble formation at GBs, and 3) by changing the precipitate distributions at boundaries. Compared to ferritic/martensitic steels, austenitic stainless steels (SS) possess good creep and fatigue resistance at elevated temperatures, and better toughness at low temperature. However, a major disadvantage of austenitic SS is that they are vulnerable to significant void swelling in nuclear reactors, especially at the temperatures and doses anticipated in the Advanced Burner Reactor. The lack of resistance to void swelling in austenitic alloys led to the switch to ferritic/martensitic steels as the preferred material for the fast reactor cladding application. Recently a type of austenitic stainless steel, HT-UPS, was developed at ORNL, and is expected to show enhanced void swelling resistance through the trapping of point defects at nanometersized carbides. Reducing the grain size and increasing the fraction of low energy grain boundaries should reduce the available radiation-produced point defects (due to the increased sink area of the grain boundaries), should make bubble nucleation at the boundaries less likely (by reducing the fraction of high-energy boundaries), and improve the strength and ductility under radiation by producing a higher

  20. Precision measurement of the top quark mass at threshold with the FCC-ee

    CERN Document Server

    Foppiani, Nicolo

    2016-01-01

    The project concerns the study of the sensitivity in measuring the Top quark mass at threshold at the FCC-ee, using a Montecarlo analysis. In particular it has been developed within the FCC software framework, using a fast simulation. The work focused firstly on developing a b-tagging algorithm inside of the FCC fast simulation, managing to obtain results comparable with the ALEPH ones, and new results with a futuristic detector like ILD. Afterwards the selection of the tt events at energy close to the pair production threshold has been studied, obtaining a selection efficiency of 55 % and a background rejection at the level of 99.4 %. In the end, a list of points that can be achieved in the future, to complete the analysis, has been identified.

  1. Direct measurement of alpha_QED(mZ)at the FCC-ee

    CERN Document Server

    Janot, Patrick

    2015-01-01

    When the measurements from the FCC-ee become available, an improved determination of the standard-model "input" parameters will be needed to fully exploit the new precision data towards either constraining or fitting the parameters of beyond-the-standard-model theories. Among these input parameters is the electromagnetic coupling constant estimated at the Z mass scale, alpha_QED(mZ). The measurement of the muon forward- backward asymmetry at the FCC-ee, just below and just above the Z pole, can be used to make a direct determination of alpha_QED(mZ) with an accuracy deemed adequate for an optimal use of the FCC-ee precision data.

  2. Preparation and Cracking Performance of FCC Co-Catalyst for Enhancing Light Oil Production

    Institute of Scientific and Technical Information of China (English)

    Wu Feiyue; Shi Li; Weng Huixin; Wang Xin

    2008-01-01

    In this paper,a FCC co-catalyst for enhancing the light oil production was prepared by the sol-gel method,and its effect on the performance of residue cracking catalysts was evaluated in a CCFFB reactor.The test results indicated that the liquid product yield increased obviously,after the surface of FCC equilibrium catalyst was impregnated with the co-catalyst.The yields of dry gas,slurry and coke decreased,while the diesel yield changed slightly.And the crackability of residue was increased; the rate of coke deposition on catalyst surface was decreased,with the thermal cracking reactions inhibited.All these results showed that the co-catalyst could improve the density of acid sites and change the catalyst acidity,which could promote to prolong the catalyst activity by depositing the co-catalyst on the surface of FCC equilibrium catalysts.

  3. First Design of a Proton Collimation System for 50 TeV FCC-hh

    CERN Document Server

    Fiascaris, Maria; Mirarchi, Daniele; Redaelli, Stefano

    2016-01-01

    We present studies aimed at defining a first conceptual solution for a collimation system for the hadron-hadron option for the Future Circular Collider (FCC-hh). The baseline collimation layout is based on the scaling of the present LHC collimation system to the FCC-hh energy. It currently includes a dedicated betatron cleaning insertion as well as collimators in the experimental insertions to protect the inner triplets. An aperture model for the FCC-hh is defined and the geometrical acceptance is calculated at top energy taking into account mechanical and optics imperfections. Based on these studies the collimator settings needed to protect the machine are defined. The performance of the collimation system is then assessed with particle tracking simulation tools assuming a perfect machine.

  4. A Technical and Economical Evaluation of CO2 Capture from Fluidized Catalytic Cracking (FCC Flue Gas

    Directory of Open Access Journals (Sweden)

    Digne Romina

    2014-11-01

    Full Text Available Environmental issues, related to greenhouse gas and among them CO2, are becoming short term challenges. Pressure on industries and therefore on refining to limit and manage CO2 emissions will be reinforced in next few years. Refining industry is responsible for about 2.7% of global CO2 emissions. Fluidized Catalytic Cracking unit (FCC, one of the main process in refining, represents by itself 20% of the refinery CO2 emissions. As FCC unit is present in half of the refining schemes, it is challenging to find technologies to manage its emissions. Based on an industrial case, the aims of the presented work are to determine if amine technology HiCapt+, developed for power plant, might be a relevant solution to manage FCC CO2 emissions and to evaluate the additional cost to be supported by refiners.

  5. The temperature behaviour of the elastic and thermodynamic properties of fcc thorium

    Energy Technology Data Exchange (ETDEWEB)

    Jaroszewicz, S., E-mail: jaroszew@tandar.cnea.gov.ar [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica, Av. Gral. Paz 1499, San Martin (Argentina); Instituto de Tecnologia Jorge A. Sabato, UNSAM-CNEA (Argentina); Mosca, H.O. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica, Av. Gral. Paz 1499, San Martin (Argentina); Instituto de Tecnologia Jorge A. Sabato, UNSAM-CNEA (Argentina); Garces, J.E. [DAEE, Centro Atomico Bariloche, Comisin Nacional de Energia Atomica, Av. Bustillo 9500, Bariloche, Rio Negro (Argentina)

    2012-10-15

    The temperature behaviour of the structural, elastical and thermal properties of fcc thorium have been calculated from a free-parameter Helmholtz free energy developed by computing the cohesive energy from first principles calculations coupled to the Chen-Moebius lattice inversion method and the Debye-Grueneisen quasiharmonic model. The elastic constants, shear modulus, Young modulus, Poisson's ratio and thermodynamic properties of fcc Th as the entropy, the harmonic specific heat, the (P, V, T) equation of state and the thermal lattice expansion are found to be in a very good agreement with experiments and ab initio phonon calculations. The results of this work show the potentiality of the Chen-Moebius method coupled to ab initio calculation of the cohesive energy to develop a free-parameter pair potential capable of giving an overall description of fcc Th properties at T = 0 K with an error similar to ab initio calculations.

  6. Towards a Monochromatization Scheme for Direct Higgs Production at FCC-ee

    CERN Document Server

    Valdivia Garcia, Marco Alan; Zimmermann, Frank

    2016-01-01

    Direct Higgs production in e+e− collisions at the FCC is of interest if the centre-of-mass energy spread can be reduced by at least an order of magnitude. A monochromatization scheme, to accomplish this, can be realized with horizontal dispersion of opposite sign for the two colliding beams at the interaction point (IP). We recall historical approaches to monochromatization, then derive a set of IP parameters which would provide the required performance in FCC e+e− collisions at 62.5 GeV beam energy, compare these with the baseline optics parameters at neighbouring energies (45.6 and 80 GeV), comment on the effect of beamstrahlung, and indicate the modifications of the FCC-ee final-focus optics needed to obtain the required parameters.

  7. Crystallographic dependence of CO activation on cobalt catalysts: HCP versus FCC.

    Science.gov (United States)

    Liu, Jin-Xun; Su, Hai-Yan; Sun, Da-Peng; Zhang, Bing-Yan; Li, Wei-Xue

    2013-11-06

    Identifying the structure sensitivity of catalysts in reactions, such as Fischer-Tropsch synthesis from CO and H2 over cobalt catalysts, is an important yet challenging issue in heterogeneous catalysis. Based on a first-principles kinetic study, we find for the first time that CO activation on hexagonal close-packed (HCP) Co not only has much higher intrinsic activity than that of face centered-cubic (FCC) Co but also prefers a different reaction route, i.e., direct dissociation with HCP Co but H-assisted dissociation on the FCC Co. The origin is identified from the formation of various denser yet favorable active sites on HCP Co not available for FCC Co, due to their distinct crystallographic structure and morphology. The great dependence of the activity on the crystallographic structure and morphology of the catalysts revealed here may open a new avenue for better, stable catalysts with maximum mass-specific reactivity.

  8. Interdiffusion and Diffusion Mobility for fcc Ni-Co-Al Alloys

    Science.gov (United States)

    Wang, Yang; Zhu, Naqiong; Wang, Hao; Lu, Xiao-Gang

    2016-12-01

    Ternary fcc Ni-Co-Al diffusion couples annealed at 1173 K (900 °C), 1373 K (1100 °C), and 1573 K (1300 °C) have been studied by using electron probe microanalysis. The interdiffusion coefficients were extracted using the Sauer-Freise and Whittle-Green methods from the measured concentration profiles of binary and ternary diffusion couples, respectively. Based on the diffusion coefficients reported in the literature and those determined in the present work, the diffusion mobilities for fcc Ni-Co-Al alloys were assessed. In general, reasonable agreements were reached and the resulted mobility database can be used to study the diffusion behavior of the ternary fcc Ni-Co-Al alloys in a wide composition range.

  9. Reducing the formation of FIB-induced FCC layers on Cu-Zn-Al austenite.

    Science.gov (United States)

    Zelaya, Eugenia; Schryvers, Dominique

    2011-01-01

    The irradiation effects of thinning a sample of a Cu-Zn-Al shape memory alloy to electron transparency by a Ga(+) focused ion beam were investigated. This thinning method was compared with conventional electropolishing and Ar(+) ion milling. No implanted Ga was detected but surface FCC precipitation was found as a result of the focused ion beam sample preparation. Decreasing the irradiation dose by lowering the energy and current of the Ga(+) ions did not lead to a complete disappearance of the FCC structure. The latter could only be removed after gentle Ar(+) ion milling of the sample. It was further concluded that the precipitation of the FCC is independent of the crystallographic orientation of the surface.

  10. Progress towards next generation hadron colliders: FCC-hh, HE-LHC, and SPPC

    Science.gov (United States)

    Zimmermann, Frank; EuCARD-2 Extreme Beams Collaboration; Future Circular Collider (FCC) Study Collaboration

    2017-01-01

    A higher-energy circular proton collider is generally considered to be the only path available in this century for exploring energy scales well beyond the reach of the Large Hadron Collider (LHC) presently in operation at CERN. In response to the 2013 Update of the European Strategy for Particle Physics and aligned with the 2014 US ``P5'' recommendations, the international Future Circular Collider (FCC) study, hosted by CERN, is designing such future frontier hadron collider. This so-called FCC-hh will provide proton-proton collisions at a centre-of-mass energy of 100 TeV, with unprecedented luminosity. The FCC-hh energy goal is reached by combining higher-field, 16 T magnets, based on Nb3Sn superconductor, and a new 100 km tunnel connected to the LHC complex. In addition to the FCC-hh proper, the FCC study is also exploring the possibility of a High-Energy LHC (HE-LHC), with a centre-of-mass energy of 25-27 TeV, as could be achieved in the existing 27 km LHC tunnel using the FCC-hh magnet technology. A separate design effort centred at IHEP Beijing aims at developing and constructing a similar collider in China, with a smaller circumference of about 54 km, called SPPC. Assuming even higher-field 20 T magnets, by relying on high-temperature superconductor, the SPPC could reach a c.m. energy of about 70 TeV. This presentation will report the motivation and the present status of the R&D for future hadron colliders, a comparison of the three designs under consideration, the major challenges, R&D topics, the international technology programs, and the emerging global collaboration. Work supported by the European Commission under Capacities 7th Framework Programme project EuCARD-2, Grant Agreement 312453, and the HORIZON 2020 project EuroCirCol, Grant Agreement 654305.

  11. Effects of Co doping on the metamagnetic states of the ferromagnetic fcc Fe-Co alloy.

    Science.gov (United States)

    Ortiz-Chi, Filiberto; Aguayo, Aarón; de Coss, Romeo

    2013-01-16

    The evolution of the metamagnetic states in the ferromagnetic face centered cubic (fcc) Fe(1-x)Co(x) alloy as a function of Co concentration has been studied by means of first-principles calculations. The ground state properties were obtained using the full-potential linear augmented plane wave method and the generalized gradient approximation for the exchange-correlation functional. The alloying was modeled using the virtual crystal approximation and the magnetic states were obtained from the calculations of the total energy as a function of the spin moment, using the fixed spin moment method. For ferromagnetic fcc Fe, the binding-energy curve shows metamagnetic behavior, with two minima corresponding to a small-volume, low-spin (LS) state and a large-volume, high-spin (HS) state, which are separated by a small energy (E(LS) ≲ E(HS)). The evolution of the magnetic moment, the exchange integral (J), and the binding-energy curve is analyzed in the whole range of Co concentrations (x). The magnetic moment corresponding to the HS state decreases monotonically from 2.6 μ(B)/atom in fcc Fe to 1.7 μ(B)/atom in fcc Co. In contrast, the exchange integral for the HS state shows a maximum at around x = 0.45. The thermal dependence of the lattice parameter is evaluated with a method based on statistical mechanics using the binding-energy curve as an effective potential. It is observed that the behavior of the lattice parameter with temperature is tuned by Co doping, from negative thermal expansion in fcc Fe to positive thermal expansion in fcc Co, through the modification of the energetics of the metamagnetic states.

  12. Calculation of the surface energy of fcc metals with modified embedded-atom method

    Institute of Scientific and Technical Information of China (English)

    Zhang Jian-Min; Ma Fei; Xu Ke-Wei

    2004-01-01

    The surface energies for 38 surfaces of fcc metals Cu, Ag, Au, Ni, Pd, Pt, Al, Pb, Rh and Ir have been calculated by using the modified embedded-atom method. The results show that, for Cu, Ag, Ni, Al, Pb and Ir, the average values of the surface energies are very close to the polycrystalline experimental data. For all fcc metals, as predicted, the close-packed (111) surface has the lowest surface energy. The surface energies for the other surfaces increase linearly with increasing angle between the surfaces (hkl) and (111). This can be used to estimate the relative values of the surface energy.

  13. Study on Reaction Mechanism for Cracking FCC Gasoline on Acid Catalyst

    Institute of Scientific and Technical Information of China (English)

    Xu Youhao; Wang Xieqing

    2004-01-01

    This article is based on the experimental data on reaction of FCC naphtha in the presence of acid catalysts. The data published in the literature were reprocessed and compared with experimental data and the relationship of hydrogen and methane contained in the dry gas with the conversion rate was identified.The similarity between the route for cracking of olefin enriched FCC gasoline and the route for reaction of individual hydrocarbons was deduced, while the route for formation of ethylene in dry gas was also proposed to identify the relationship between the reaction path for formation of ethylene and the conversion rate.

  14. Esfuerzo triaxial ideal de Ti, Zr y Hf con estructura fcc: un estudio de primeros principios

    OpenAIRE

    A. Bautista Hernández; J.H. Camacho García; M. Salazar Villanueva; E. Chigo Anota; A. Macias Cervantes

    2011-01-01

    A temperatura y presión ambiente el Ti, Zr y Hf cristalizan en la fase hexagonal compacta. Recientemente se ha reportado que estos elementos son élasticamente metaestables [14] en la estructura cúbica centrada en las caras (fcc). En este trabajo presentamos el esfuerzo triaxial ideal de los metales Ti, Zr y Hf con estructura fcc, obtenido mediante cálculos de primeros principios usando la teoría del funcional de la densidad. Se usó la aproximación de gradiente generalizado y local de la densi...

  15. Micromagnetic simulations of interacting dipoles on an fcc lattice: application to nanoparticle assemblies.

    Science.gov (United States)

    Plumer, M L; van Lierop, J; Southern, B W; Whitehead, J P

    2010-07-28

    Micromagnetic simulations are used to examine the effects of cubic and axial anisotropy, magnetostatic interactions and temperature on M-H loops for a collection of magnetic dipoles on fcc and sc lattices. We employ a simple model of interacting dipoles that represent single-domain particles in an attempt to explain recent experimental data on ordered arrays of magnetoferritin nanoparticles that demonstrate the crucial role of interactions between particles in an fcc lattice. Significant agreement between the simulation and experimental results is achieved, and the impact of intra-particle degrees of freedom and surface effects on thermal fluctuations is investigated.

  16. Determination of Sulfides in FCC Gasoline by Using the Potentiometric Titration of Lead Tetraacetate

    Institute of Scientific and Technical Information of China (English)

    罗立文; 夏道宏

    2004-01-01

    Compared with conventional method of violet spectrum, determination of the content of sulfides in fluid catalytic cracking (FCC) gasoline by using the potentiometric titration of lead tetraacetate has some advantages such as clear potentiometric abrupt change at the stoichiometric point, stable potentiometric value, exact and credible results, and simple operation. The content of sulfides in FCC gasoline of Shenghua refinery is 0.136% by this method. The standard deviation about this method is less than 0.01% and the relative standard deviation is less than 2.42%.

  17. Ultrasonic Products FCC PART 18 Test Methods%超声波产品FCC PART 18的测试方法

    Institute of Scientific and Technical Information of China (English)

    吴建宏

    2015-01-01

    针对超声波产品出口美国的FCC认证要求,对此类产品FCC Part 18的测试进行了解读,阐述了详细技术要求以及跟其它产品测试方法的不同,并对此注意事项进行了分析.

  18. Increase of propylene production and recovery in a PETROBRAS FCC units; Aumento da producao e recuperacao de propeno em uma Unidade de FCC da PETROBRAS

    Energy Technology Data Exchange (ETDEWEB)

    Penna, Elisangela Melo; Pinho, Andrea de Rezende; Wolff, Marcelo Straubel [Petroleo Brasileiro S.A (PETROBRAS), Rio de Janeiro, RJ (Brazil)

    2012-07-01

    Propylene is one of the major petrochemical raw materials and its demand has been growing rapidly in recent years. Projections for future years indicate that the growth in propylene production via pyrolysis tends to be lower than the growth in the demand for ethylene, creating a supply deficit of this product. The FCC units are in a unique position to meet this increase in propylene demand due to its operational flexibility. Although their primary function in recent decades has been the gasoline production, FCC units are often operated for maximizing other products, such as LPG or distillates. At the FCC conversion section, the increase of propylene yield requires some increase in reaction severity, which can be obtained by increasing reactor riser temperature, and the use of catalyst additives based on ZSM-5. However, besides maximizing the propylene production in the reactor, a second objective should be pursued: the propylene recovery increase in the gas recovery section. In this section, the yield is affected by the gas compressor performance, the equipment design and process scheme. Eventually, new equipment may be installed, such as chillers, aimed at improving the absorption system. Predicting a real increase in propylene demand in the Brazilian market, this study aims to evaluate the adequacy of the gas recovery section of a PETROBRAS FCC unit, analyzing the impacts that a new products yields profile, which bend the propylene production compared to a conventional operation, would cause on this unit. In this paper, the main limitations and modifications that would be needed for an operation were identified, aiming at maximizing the propylene production, as well as proposed changes in the hardware of the unit. (author)

  19. Maximizing light olefins production in fluid catalytic cracking (FCC) units; Maximizacao de olefinas leves em unidades de craqueamento catalitico fluido

    Energy Technology Data Exchange (ETDEWEB)

    Pimenta, Ricardo D.M.; Pinho, Andrea de Rezende [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2004-07-01

    The Fluid Catalytic Cracking (FCC) process is widely spread over the ten PETROBRAS refineries in its thirteen industrial units. The importance of the FCC process resides on its high gasoline output, being the main supplier of this important product to the system. Additionally, FCC process is the main source of light hydrocarbons in the LPG range, including light olefins. The increasing demand for ethylene, propylene and butylenes was encouraging to concentrate the research efforts on studies about alternatives for the traditional FCC process. In the present work, the proposals from main licensors (UOP, KBR, Stone and Webster) for a light-olefins-driven FCC process (Petrochemical FCC) will be compared. Furthermore, the catalytic route for light olefins production in FCC units is also described. An additive based on ZSM- 5 zeolite, which is produced following a PETROBRAS proprietary technology, is being largely applied into the catalyst inventories of all FCC units. An analysis of different scenarios was performed to estimate the maximum potential of light olefins production from the highest possible ZSM-5 additive usage. More specifically for the case of ethylene, which production is also boosted by the same type of additive, studies are being conducted with the objective of recovering it from a C2 stream using specific units to do the splitting (UPGR). The search for increasing light olefins production in the refining processes is in line with PETROBRAS strategic plan which targeted for the company a more intense activity in the Brazilian petrochemical market (author)

  20. La{sub 2}NiTiO{sub 6}: A 3D S=1 fcc Heisenberg antiferromagnet

    Energy Technology Data Exchange (ETDEWEB)

    Karolak, Michael; Edelmann, Martin; Sangiovanni, Giorgio [Institut fuer Theoretische Physik und Astrophysik, Universitaet Wuerzburg (Germany)

    2015-07-01

    A DFT+DMFT analysis of the double perovskite La{sub 2}NiTiO{sub 6} reveals the crystal to exhibit a nearly unfrustrated three-dimensional ordering of local magnetic moments of S=1 on an fcc sublattice. In DFT, La{sub 2}NiTiO{sub 6} shows a peculiar bandstructure in which the Ni e{sub g} bands are half-filled and split from bands of other character by at least 0.5 eV. The bandwidth of Ni e{sub g} is around 0.8 eV, which is attributed to strongly reduced hopping amplitudes caused by the Ti sites. By Wannier projection on the correlated subspace of only Ni e{sub g}, an effective direct exchange model is derived to obtain quantitative values for the superexchange coupling between Ni sites. Comparing nearest-neighbour to next-nearest-neighbour coupling, the latter exceeds the former by a factor of 4 at minimum. This causes a nearly unfrustrated antiferromagnetic ordering of the local moments, whose Neel temperature is low not as a result of frustration but of strong correlation, as is revealed by an investigation of the kinetic and potential energy differences between ordered an unordered phase. The double perovskite La{sub 2}NiTiO{sub 6} is identified as an interesting S=1 quantum antiferromagnet on a three-dimensional fcc sublattice. By means of Density Functional Theory (DFT) in combination with Dynamical Mean Field Theory (DMFT) it is demonstrated that this material is a high-spin d-electron system deep in the Heisenberg limit and established that its paramagnetic Mott phase persists down to low temperatures not because of frustration effects but rather for the strong coupling physics. Our many-body calculations on an ab initio-derived multi-orbital basis predict indeed a kinetic energy gain when entering the magnetically ordered phase. The strong-coupling nature is assessed from a multi-orbital DFT+DMFT analysis of the energetic balance between the ordered and disordered phase, which reveals a kinetic-energy-driven ordering. La{sub 2}NiTiO{sub 6} emerges thus as a

  1. Critical driving force for martensitic transformation fcc (γ)→hcp(ε) in Fe-Mn-Si shape memory alloys

    Institute of Scientific and Technical Information of China (English)

    金学军; 徐祖耀; 李麟

    1999-01-01

    By the application of Chou’s new geometry model and the available data from binary Fe-Mn, Fe-Si and Mn-Si systems, as well as SGTE DATA for lattice stability parameters of three elements from Dinsdale, the Gibbs free energy as a function of temperature of the fcc(γ) and hep(ε) phases in the Fe-Mn-Si system is reevaluated. The relationship between the Neel temperature of the γ phase and concentration of constituents in mole fraction, is fitted and verified by the experimental results. The critical driving force for the martensitic transformation fcc (γ)→ hep (ε), △ GCγ→ε, defined as the free energy difference between γ and ε phases at Ms of various alloys can also be obtained with a known Ms. It is found that the driving force varies with the composition of alloys, e. g. △ GCγ→ε = - 100.99 J/mol in Fe-27.0Mn-6.0Si and △ GCγ→ε = - 122.11 J/mol in Fe-26.9Mn-3.37Si. The compositional dependence of critical driving force accorded with the expression formulated by Hsu of the

  2. Fluid Catalytic Cracking Feed Hydrotreatment and its Impact on Distribution of Sulfur and Nitrogen Compounds in FCC Diesel

    Institute of Scientific and Technical Information of China (English)

    Bai Rui; Chai Yongming; Zhang Chengtao; Liu Chenguang

    2015-01-01

    The sulfides and nitrogen compounds in FCC diesel were analyzed by gas chromatography equipped with a pulsed lfame photometric detector (GC-PFPD) and gas chromatography coupled with nitrogen chemiluminescence detection (GC-NCD). And the variation of sulifdes and nitrogen compounds in FCC diesel produced from gas oil feed hydrotreated at different temperatures was investigated. The test results showed that two main types of sulfur compounds, i.e. benzothio-phenes (BTs) and dibenzothiophenes (DBTs) were found in diesel. Nitrogen compounds are mainly composed of non-basic nitrogen compounds, and indoles and carbazoles account for about 98% of the total nitrogen contents. The sulifdes in FCC diesel obtained from hydrotreated feed are mainly BTs with a small amount of 4-MDBT and 4,6-DMDBT. With the increase in FCC feed hydrotreating temperature, indoles content in FCC diesel increases, while carbazoles content decreases.

  3. 5 CFR 3902.102 - Employees required to submit FCC Form A54A, “Confidential Supplemental Statement of Employment...

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 3 2010-01-01 2010-01-01 false Employees required to submit FCC Form... REQUIREMENTS FOR EMPLOYEES OF THE FEDERAL COMMUNICATIONS COMMISSION § 3902.102 Employees required to submit FCC... file FCC Form A54A, “Confidential Supplemental Statement of Employment and Financial Interests.”...

  4. 47 CFR 3.53 - FCC notification of refusal to provide telecommunications service to U.S. registered vessel(s).

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false FCC notification of refusal to provide...-SATELLITE RADIO SERVICES Settlement Operations § 3.53 FCC notification of refusal to provide telecommunications service to U.S. registered vessel(s). An accounting authority must inform the FCC...

  5. Nitrogen Chemistry and Coke Transformation of FCC Coked Catalyst during the Regeneration Process

    Science.gov (United States)

    Shi, Junjun; Guan, Jianyu; Guo, Dawei; Zhang, Jiushun; France, Liam John; Wang, Lefu; Li, Xuehui

    2016-01-01

    Regeneration of the coked catalyst is an important process of fluid catalytic cracking (FCC) in petroleum refining, however, this process will emit environmentally harmful gases such as nitrogen and carbon oxides. Transformation of N and C containing compounds in industrial FCC coke under thermal decomposition was investigated via TPD and TPO to examine the evolved gaseous species and TGA, NMR and XPS to analyse the residual coke fraction. Two distinct regions of gas evolution are observed during TPD for the first time, and they arise from decomposition of aliphatic carbons and aromatic carbons. Three types of N species, pyrrolic N, pyridinic N and quaternary N are identified in the FCC coke, the former one is unstable and tends to be decomposed into pyridinic and quaternary N. Mechanisms of NO, CO and CO2 evolution during TPD are proposed and lattice oxygen is suggested to be an important oxygen resource. Regeneration process indicates that coke-C tends to preferentially oxidise compared with coke-N. Hence, new technology for promoting nitrogen-containing compounds conversion will benefit the in-situ reduction of NO by CO during FCC regeneration. PMID:27270486

  6. Formation of deformation substructures in FCC crystals under the influence of point defect fluxes

    OpenAIRE

    Matveev, M. V.; Selivanikova, Olga Valerievna; Cherepanov, Dmitry Nikolaevich

    2016-01-01

    The article deals with sub-structural transformations in FCC crystals under the influence of point defect fluxes. Different relationships between accumulation of point defects in crystal and substructure transformations, in particular during the process of fragmented dislocation structure formation have been received.

  7. Rheological Modeling with Hookean Bead-Spring Cubes (SC, BBC and FCC)

    NARCIS (Netherlands)

    Denneman, A.I.M.; Jongschaap, R.J.J.; Mellema, J.

    1998-01-01

    In this study a general bead-spring model is used for predicting some rheological properties of a cubic bead-spring structure of arbitrary size immersed in a Newtonian solvent. The topology of this bead-spring structure is based upon the well-known cubic crystals (SC, BCC or FCC) and it consists of

  8. Towards an unbiased comparison of CC, BCC, and FCC lattices in terms of prealiasing

    KAUST Repository

    Vad, Viktor

    2014-06-01

    In the literature on optimal regular volume sampling, the Body-Centered Cubic (BCC) lattice has been proven to be optimal for sampling spherically band-limited signals above the Nyquist limit. On the other hand, if the sampling frequency is below the Nyquist limit, the Face-Centered Cubic (FCC) lattice was demonstrated to be optimal in reducing the prealiasing effect. In this paper, we confirm that the FCC lattice is indeed optimal in this sense in a certain interval of the sampling frequency. By theoretically estimating the prealiasing error in a realistic range of the sampling frequency, we show that in other frequency intervals, the BCC lattice and even the traditional Cartesian Cubic (CC) lattice are expected to minimize the prealiasing. The BCC lattice is superior over the FCC lattice if the sampling frequency is not significantly below the Nyquist limit. Interestingly, if the original signal is drastically undersampled, the CC lattice is expected to provide the lowest prealiasing error. Additionally, we give a comprehensible clarification that the sampling efficiency of the FCC lattice is lower than that of the BCC lattice. Although this is a well-known fact, the exact percentage has been erroneously reported in the literature. Furthermore, for the sake of an unbiased comparison, we propose to rotate the Marschner-Lobb test signal such that an undue advantage is not given to either lattice. © 2014 The Eurographics Association and John Wiley & Sons Ltd. Published by John Wiley & Sons Ltd.

  9. Nitrogen Chemistry and Coke Transformation of FCC Coked Catalyst during the Regeneration Process.

    Science.gov (United States)

    Shi, Junjun; Guan, Jianyu; Guo, Dawei; Zhang, Jiushun; France, Liam John; Wang, Lefu; Li, Xuehui

    2016-06-08

    Regeneration of the coked catalyst is an important process of fluid catalytic cracking (FCC) in petroleum refining, however, this process will emit environmentally harmful gases such as nitrogen and carbon oxides. Transformation of N and C containing compounds in industrial FCC coke under thermal decomposition was investigated via TPD and TPO to examine the evolved gaseous species and TGA, NMR and XPS to analyse the residual coke fraction. Two distinct regions of gas evolution are observed during TPD for the first time, and they arise from decomposition of aliphatic carbons and aromatic carbons. Three types of N species, pyrrolic N, pyridinic N and quaternary N are identified in the FCC coke, the former one is unstable and tends to be decomposed into pyridinic and quaternary N. Mechanisms of NO, CO and CO2 evolution during TPD are proposed and lattice oxygen is suggested to be an important oxygen resource. Regeneration process indicates that coke-C tends to preferentially oxidise compared with coke-N. Hence, new technology for promoting nitrogen-containing compounds conversion will benefit the in-situ reduction of NO by CO during FCC regeneration.

  10. An alternative explanation for epitaxial growth. The case of fcc(111) on bcc(110)

    DEFF Research Database (Denmark)

    Grey, F.; Bohr, J.

    1993-01-01

    Starting from basic observations concerning commensurate structures, a simple explanation is given for the existence of energetically stable states of an fcc(111) adsorbate on a bcc(110) substrate, as a function of the mismatch and relative orientation of the two lattices. Numerical simulations...

  11. Band structure of fcc-C60 solid state crystal study

    Directory of Open Access Journals (Sweden)

    S Javanbakht

    2009-09-01

    Full Text Available We studied the architecture of the C60 cluster to drive its atomic positions which can be seen at room temperature. We then used the obtained carbon positions as a basis set for the fcc structure to construct the fcc-C60 compound. Self consistent calculations were performed based on the density functional theory (DFT utilizing the accurate WIEN2K code to solve the single-particle Kohen-Sham equation within the augmented plane waves plus local orbital (APW+lo method. The cohesive energy has been found to be 1.537 eV for the fcc-C60 . The calculated small cohesive energy that results from the weak Van der Waals-London interactions among a C60 cluster with its nearest neighbors is in good agreement with experiment. The electron densities of states (DOSs were calculated for a C60 macromolecule as well as the fcc-C60 compound and the results were compared with each other. The band gap from DOS calculations has been found to be 0.7 eV. Band structures were also calculated within the generalized gradient approximation (GGA. The band structure calculation results in 1.04 eV for the direct band gap. Two kinds of σ and π bonds were determined in the band structure. Our results are in good agreement with experiment and pseudopotential calculations.

  12. 78 FR 44121 - FCC Extends Reply Comment Dates for Indecency Cases Policy

    Science.gov (United States)

    2013-07-23

    ... COMMISSION FCC Extends Reply Comment Dates for Indecency Cases Policy AGENCY: Federal Communications... concerns. Therefore, the extended deadline for filing reply comments is August 2, 2013. DATES: Reply... file reply comments on or before the date indicated on the first page of this document. Reply...

  13. Nitrogen Chemistry and Coke Transformation of FCC Coked Catalyst during the Regeneration Process

    Science.gov (United States)

    Shi, Junjun; Guan, Jianyu; Guo, Dawei; Zhang, Jiushun; France, Liam John; Wang, Lefu; Li, Xuehui

    2016-06-01

    Regeneration of the coked catalyst is an important process of fluid catalytic cracking (FCC) in petroleum refining, however, this process will emit environmentally harmful gases such as nitrogen and carbon oxides. Transformation of N and C containing compounds in industrial FCC coke under thermal decomposition was investigated via TPD and TPO to examine the evolved gaseous species and TGA, NMR and XPS to analyse the residual coke fraction. Two distinct regions of gas evolution are observed during TPD for the first time, and they arise from decomposition of aliphatic carbons and aromatic carbons. Three types of N species, pyrrolic N, pyridinic N and quaternary N are identified in the FCC coke, the former one is unstable and tends to be decomposed into pyridinic and quaternary N. Mechanisms of NO, CO and CO2 evolution during TPD are proposed and lattice oxygen is suggested to be an important oxygen resource. Regeneration process indicates that coke-C tends to preferentially oxidise compared with coke-N. Hence, new technology for promoting nitrogen-containing compounds conversion will benefit the in-situ reduction of NO by CO during FCC regeneration.

  14. Insulating fcc YH3-δ stabilized by MgH2

    NARCIS (Netherlands)

    Molen, van der S.J.; Nagengast, D.G.; Gogh, van A.T.M.; Kalkman, J.; Kooij, E.S.; Rector, J.H.; Griessen, R.

    2001-01-01

    We study the structural, optical, and electrical properties of MgzY1-z switchable mirrors upon hydrogenation. It is found that the alloys disproportionate into essentially pure YH3-δ and MgH2 with the crystal structure of YH3-δ dependent on the Mg concentration z. For 0fcc YH3-δ

  15. Structural Changes of α Phase in Furnace Cooled Eutectoid Zn-Al Based Alloy

    Institute of Scientific and Technical Information of China (English)

    Y.H. Zhu; K.C. Chan; G.K.H. Pang; T.M. Yue; W.B. Lee

    2007-01-01

    Furnace cooling is a slow cooling process. It is of importance to study structural evolution and its effects on the properties of alloys during the furnace cooling. Decomposition of aluminium rich α phase in a furnace cooled eutectoid Zn-Al based alloy was studied by transmission electron microscopy. Two kinds of precipitates in the α phase were detected in the FCZA22 alloy during ageing at 170℃. One was the hcp transitional α"m phase which appears as directional rods and the round precipitates. The other was the fcc α'm phase.It was found that the transitional phase α'm grew in three preferential directions of , and . The orientation relationship between the α phase and transitional phase α'm was determined as (02-2)α'm(fcc)//(02-2)α(fcc), [-111]α'm(fcc)//[-233]α(fcc). The non-equilibrium phase decomposition of the α phase is discussed in correlation with the equilibrium phase relationships.

  16. Molecular dynamics simulations of stress-induced phase transformations and grain nucleation at crack tips in Fe

    Science.gov (United States)

    Latapie, A.; Farkas, D.

    2003-09-01

    The molecular dynamics simulation technique is used to study a stress-induced new grain formation mechanism at the crack tip of a nanocrystalline alpha-iron sample at temperatures ranging from 100 to 600 K. The stress-induced formation of new bcc grains, created inside existing grains, is found to occur through a metastable bcc to fcc phase transformation at the crack tip of the sample. A Nishiyama-Wassermann orientation relationship is found between the original bcc grain and the fcc phase and a Kurdjumov-Sachs orientation relationship is found between the new bcc grain created and the fcc transition phase. The new grain nucleation is observed to increase with increasing temperature and stacking faults associated with the fcc phase are observed at the higher temperatures.

  17. Boron fullerenes B(32+8k) with four-membered rings and B32 solid phases: geometrical structures and electronic properties.

    Science.gov (United States)

    Sheng, Xian-Lei; Yan, Qing-Bo; Zheng, Qing-Rong; Su, Gang

    2009-11-14

    Based on ab initio calculations, we have studied the geometrical, electronic properties and chemical bonding of boron fullerenes B(32+8k) (0 cubic (sc), face-centered cubic (fcc), body-centered cubic (bcc), and body-centered tetragonal (bct) structures, where the bct phase is observed to be the most stable. Electronic structure calculations reveal that the sc, fcc and bcc phases of B(32) solids are metallic, but the bct phase is a semimetal.

  18. X-ray diffraction and Mössbauer spectroscopy study of fcc iron hydride FeH at high pressures and implications for the composition of the Earth's core

    Science.gov (United States)

    Narygina, Olga; Dubrovinsky, Leonid S.; McCammon, Catherine A.; Kurnosov, Alexander; Kantor, Innokenty Yu.; Prakapenka, Vitali B.; Dubrovinskaia, Natalia A.

    2011-07-01

    The phase fcc FeH x (x ~ 1) was synthesized at pressures over 30 GPa and temperatures over 1600(50) K. At room temperature this iron hydride is stable at pressures from 19(1) GPa up to at least 68(2) GPa (the highest pressure achieved in this study). A fit of the PV data collected for fcc FeH x at room temperature gives the following parameters for the equation of state: V 0 = 53.8(3) Å 3, K 0 = 99(5) GPa, K' = 11.7(5). Using this data the amount of H required to match the density of the Earth's core was estimated to be 0.5-1 wt.% hydrogen in the outer core and 0.08-0.16 wt.% hydrogen in the inner core. Our results also suggest that hydrogen and carbon do not occur together in the Earth's core.

  19. Microstructural investigation of Nd-rich phase in sintered Nd-Fe-B magnets through electron microscopy

    Institute of Scientific and Technical Information of China (English)

    付新; 韩小磊; 杜志伟; 冯海波; 李岩峰

    2013-01-01

    The distribution, morphologies and structures of intergranular Nd-rich phase in sintered Nd-Fe-B magnets were studied through electron microscopy. Backscattered electron (BSE) imaging revealed that Nd-rich particles with various morphologies and sizes were randomly distributed at the grain boundaries and the triple junctions of the tetragonal Nd2Fe14B matrix. Through selected area electron diffraction (SAED) analysis under a systematic tilting condition, most intergranular Nd-rich phase particles, with sizes ranging from hundreds of nanometres to several micrometres, were identified as face-centred cubic (FCC) structure. Such particles possessed several approximate orientation relationships with their adjacent Nd2Fe14B matrix grains, such as (002)Nd2Fe14B//(200)FCC_Nd-rich [120] Nd2Fe14B//[001]FCC_Nd-rich, (002)Nd2Fe14B//( 220 )FCC_Nd-rich [110] Nd2Fe14B//[112]FCC_Nd-rich, as well as (011)Nd2Fe14B//(131)FCC_Nd-rich [111] Nd2Fe14B//[114]FCC_Nd-rich, which could be attributed to minimising interfacial energy. The combination of high-resolution electron microscopy with energy-dispersive X-ray spectroscopy revealed the internal inhomogeneous nature of Nd-rich phases. The large lattice distortion and nanoscale-ordered structures within a single Nd-rich grain were observed.

  20. Diffusivities and atomic mobilities in disordered fcc and ordered L1{sub 2} Ni–Al–W alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chong [State Key Lab of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Zhang, Lijun, E-mail: xueyue168@gmail.com [State Key Lab of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Xin, Jinghua; Wang, Yaru [State Key Lab of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Du, Yong, E-mail: yong-du@csu.edu.cn [State Key Lab of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Luo, Fenghua [State Key Lab of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Zhang, Zhongjian; Xu, Tao; Long, Jianzhan [State Key Lab of Cemented Carbides, Zhuzhou, Hunan 412000 (China)

    2015-10-05

    Highlights: • The atomic mobilities for fcc Al–W, fcc Ni–W, fcc Ni–Al–W and L1{sub 2} Ni–Al–W alloys were critically assessed. • The impurity diffusivity of W in fcc-Al was obtained via first-principles calculations. • The calculated results agree well with the diffusivities available in the literature. • Two fcc/L1{sub 2}-type diffusion couples were prepared and the concentration-distance profiles were measured. • The model-predicted concentration profiles agree well with the experimental data in the literature and in the present work. - Abstract: Based on various experimentally measured diffusivities available in the literature together with the reported thermodynamic parameters, the atomic mobilities for disordered fcc and ordered L1{sub 2} Ni–Al–W alloys were assessed on the basis of a recently developed phenomenological model incorporated in the DICTRA software. In order to provide the missing impurity diffusion coefficients of W in fcc-Al, first-principles calculations were utilized in the present work. Comprehensive comparisons between the calculated and experimental diffusion coefficients show that all the experimental data can be well reproduced by the atomic mobilities obtained in the present work. In order to further verify the reliability of the presently obtained atomic mobilities, two fcc/L1{sub 2}-type diffusion couples (i.e., Ni–5 at.% Al–5 at.% W/Ni–20 at.% Al–4 at.% W and Ni/Ni–22 at.% Al–2 at.% W) were prepared and the concentration-distance profiles after annealing at 1323 K for 86.4 ks were measured. The excellent agreement between the model-predicted concentration-distance profiles and the experimental data indicates that the presently obtained atomic mobilities in fcc/L1{sub 2} Ni–Al–W alloys are reliable.

  1. Communication government agencies: the case of FCC/ Organismos de regulación y control de las comunicaciones: el caso de la FCC

    Directory of Open Access Journals (Sweden)

    Dra. Ana I. Segovia Alonso; asegovia@ccinf.ucm.es

    2009-01-01

    Full Text Available The Federal Communications Commission (FCC is one of the pioneering regulatory agencies in relation to the communication system within the capitalist model. From a general perspective, beginning with its constitution, plan of action, and regulatory decisions, we carry out a research of the historical, political and economic conditions under which this commission operates and was created. The main objective is to outline the reasons for the failures and mistakes of the FCC, that has been accused –since its origins- of acting in defence of the industry interests it seemingly regulates, and not in the public interest; and of being a creature of Congress, with no real independence from the politic, economic, and judiciary power. The final purpose of this essay is to suggest the necessary democratization of the communicative space, which needs an agency transformation that could change the current defence of the existing status quo. La Comisión Federal de Comunicaciones (FCC es uno de los organismos pioneros en el control y regulación del sistema comunicativo en el modelo capitalista. Desde una mirada general a partir de su composición, formas de actuación, y decisiones normativas, se realiza un estudio de los condicionamientos históricos, políticos y económicos bajo los cuales se crea y desarrolla su labor esta Comisión. El objetivo fundamental es delinear las razones de los errores y negligencias de la FCC, acusada desde sus inicios de actuar en defensa de los intereses de la industria a la que pretende regular, y no en interés del público; y de ser una criatura del Congreso sin independencia del poder político, ni económico, ni judicial. El propósito final del presente artículo es plantear la necesaria democratización del espacio comunicativo, que pasa por una transformación de estos organismos y su defensa del status quo existente.

  2. Transition-sized Au92 nanoparticle bridging non-fcc-structured gold nanoclusters and fcc-structured gold nanocrystals.

    Science.gov (United States)

    Liao, Lingwen; Chen, Jishi; Wang, Chengming; Zhuang, Shengli; Yan, Nan; Yao, Chuanhao; Xia, Nan; Li, Lingling; Bao, Xiaoli; Wu, Zhikun

    2016-10-04

    Herein, we report the intriguing structure, optical absorption and electrochemical properties of the transition-sized Au92(TBBT)44 (Au92 for short, TBBT = 4-tert-butylbenzenethiolate) nanoparticle. An interesting observation is the 4H phase array of Au92 nanoparticles in the unit cells of single crystals.

  3. Structural and magnetic phase formation in nanophase brass–iron electron compounds

    Indian Academy of Sciences (India)

    A K Mishra; C Bansal

    2005-11-01

    Starting with Cu0.65Zn0.35 with an e/a ratio of 1.35 we studied the phase formation in nanophase (Cu0.65Zn0.35)1−Fe alloys in the concentration range 0.1 ≤ ≤ 0.7 to see the effect of altering the electron concentration. The evolution of bcc phase from the fcc phase as a function of Fe concentration was investigated by Mössbauer spectroscopy and X-ray diffraction. The grain size, lattice parameters, and average hyperfine magnetic field distributions were estimated for the nanophase alloys. The fcc phase was observed to persist up to 40 atomic per cent Fe substitutions, a mixed (fcc + bcc) phase region up to 70 atomic per cent Fe and bcc phase beyond 70 atomic per cent Fe. The magnetic state of the alloys changed from nonmagnetic for ≤ 0.3 to magnetically ordered state at room temperature for ≥ 0.33, which lies in the fcc phase region. The fcc phase alloys of Fe with non-magnetic metals have very low magnetic transition temperatures. However, in this system the room temperature state is unusually magnetic.

  4. Cloning and Sequence analysis of LDH gene of Plasmodium Falciparum isolate FCC1/HN.%恶性疟原虫FCC1/HN株LDH基因的克隆及序列分析

    Institute of Scientific and Technical Information of China (English)

    单志新; 余新炳; 马长玲; 陈守义; 卞国武

    2001-01-01

    目的克隆并测定恶性疟原虫海南(FCC1/HN)株LDN基因序列,比较FCC1/HN株与国外分离株LDH基因序列的差异.方法根据LDH基因已知序列设计合成一对引物,应用PCR技术从FCC1/HN株基因组DNA中扩增LDH基因,并将其克隆入pMD18-T载体.用双脱氧链末端终止法进行基因序列测定,并用分子生物学软件进行不同分离株LDH基因序列的同源性比较.结果 PCR扩增得到特异的FCC1/HN株LDH基因片段并构建了pT-LDH重组质粒.恶性疟原虫FCC1/HN株LDH基因全长951bp,编码316个氨基酸.序列分析表明,我国恶性疟原虫FCC1/HN株与国外的3D7、Honduras 1株LDH基因编码氨基酸序列完全一致.结论成功克隆恶性疟原虫FCC1/HN株LDH基因.序列测定及同源性分析表明,FCC1/HN株与其它分离株的LDH基因序列高度保守.

  5. Coexistence of charge and ferromagnetic order in fcc Fe.

    Science.gov (United States)

    Hsu, Pin-Jui; Kügel, Jens; Kemmer, Jeannette; Parisen Toldin, Francesco; Mauerer, Tobias; Vogt, Matthias; Assaad, Fakher; Bode, Matthias

    2016-03-14

    Phase coexistence phenomena have been intensively studied in strongly correlated materials where several ordered states simultaneously occur or compete. Material properties critically depend on external parameters and boundary conditions, where tiny changes result in qualitatively different ground states. However, up to date, phase coexistence phenomena have exclusively been reported for complex compounds composed of multiple elements. Here we show that charge- and magnetically ordered states coexist in double-layer Fe/Rh(001). Scanning tunnelling microscopy and spectroscopy measurements reveal periodic charge-order stripes below a temperature of 130 K. Close to liquid helium temperature, they are superimposed by ferromagnetic domains as observed by spin-polarized scanning tunnelling microscopy. Temperature-dependent measurements reveal a pronounced cross-talk between charge and spin order at the ferromagnetic ordering temperature about 70 K, which is successfully modelled within an effective Ginzburg-Landau ansatz including sixth-order terms. Our results show that subtle balance between structural modifications can lead to competing ordering phenomena.

  6. 75 FR 42376 - Proposed Information Collection; Comment Request; NTIA/FCC Web-based Frequency Coordination System

    Science.gov (United States)

    2010-07-21

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE National Telecommunications and Information Administration Proposed Information Collection; Comment Request; NTIA/FCC Web- based Frequency Coordination System AGENCY: National Telecommunications and...

  7. A MODIFIED FCC PROCESS FOR MAXIMIZING ISOPARAFFINS (MIP) IN CRACKED NAPHTHA

    Institute of Scientific and Technical Information of China (English)

    XUYou-hao; ZHANGJiu-shun; LONGJun; HEMing-yuan; XUhui

    2003-01-01

    A concept of two different reaction zones was proposed based on the FCC reaction mechanism.The concept was used to design a novel reactor with corresponding operation measures.Experiments were conducted on the newly designed pilot-plant riser reactor.In comparison with the conventional FCC at relatively equivalent conversion,the pilot-plant test results showed that the olefin content in the cracked naphtha dropped by 12.4% ,and both cintents of iso-paraffin and aromatic increased by 6%,and its MON increased by 1.3 units while maintaining the RON of the naphtha unchanged,and its sulfur content reduced by 15% with a significant extension of its induction period for Shengli VGO+VR.The run test results of commercial trial were conformable with the results of pilot -plant test.

  8. Hard Corrections in Precision QCD for LHC and FCC Physics: A New Approach

    CERN Document Server

    Ward, B F L

    2016-01-01

    With an eye toward the usual unphysical divergence of hard fixed-order corrections in predictions for the processes probed in high energy colliding hadron beam devices as one approaches the soft limit, we present a new approach to the realization of such corrections, with some emphasis on the LHC and the future FCC devices. We show that the respective divergence is removed in our approach. This means that we would render the standard results to be closer to the observed exclusive distributions. While we stress that the approach has general applicability, we use the single Z and virtual gamma production and decay to lepton pairs as our prototypical example. Accordingly, our work opens another part of the way to rigorous baselines for the determination of the theoretical precision tags for LHC physics, with an attendant generalization to the future FCC.

  9. Further discussion of orientation relationships, surface reliefs and FCC-BCC transformations in steels

    Energy Technology Data Exchange (ETDEWEB)

    Dahmen, U. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials and Molecular Research Division; Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

    1981-04-01

    In response to a recent discussion in this journal concerning tent-shaped surface-relief effects and the mechanism of formation of Widmanstätten ferrite and lower bainite, it was shown that Bhadeshia's (1) explanation of surface reliefs is in error. A degeneracy of the fcc → hcp type does not exist for an fcc → bcc transformation. Based on a distinction between the symmetries of the matrix, the transformation product and the strain (5), a general rule was derived for the occurrence of the type of crystallographic degeneracies described by Bhadeshia. The present paper confirmed Aaronson's (4) contention that the transformation is not shear-like (martensitic) in nature but diffusion controlled. Finally, it was argued, however, that the formal treatment of diffusional transformations may involve a shear.

  10. A New FCC Process MIP for Production of Clean Gasoline Component

    Institute of Scientific and Technical Information of China (English)

    Xu Youhao; Zhang Jiushun; Long Jun; Wang Xieqing

    2001-01-01

    A concept of two different reaction zones was proposed based on the FCC reaction mechanism,and verified by the experimental results of a fixed fluidized bed reactor. The concept was used to design a novel reactor with corresponding operation measures. Further experiments were conducted on the newly designed pilot scale riser reactor. In comparison with the conventional FCC at relatively equivalent conversion,the pilot test results had shown that the olefin content in the cracked naphtha dropped by 12.4%, and both of iso-paraffin and aromatics increased by 6%, and its MON increased by 1.3 units while maintaining the RON of the naphtha unchanged, and its sulfur content was reduced by 15% with a significant extension of its induction period for Shengli VGO + VR.

  11. Dependency of deformation twinning on grain orientation in an FCC and a HCP metal

    Institute of Scientific and Technical Information of China (English)

    YANG Ping

    2007-01-01

    Twinning plays important roles in HCP metals and those FCC metals with low stacking fault energy.The structural difierence of two types of metals makes quite different contributions of twinning to plasticity The variety of grain orientation in polycrystalline metals causes the inhomogeneous occurrence of twinning and further distinct transformation kinetics of twinning as strain increases and texture develops.This changes finally the work hardening behavior and mechanical properties.This Paper reveals the dependency of twinning on grain orientation in an FCC TWIP(twinning induced plasticity)steel with high Mn content and in a magnesium alloy using electron-backscatter-difiraction(EBSD) technique,and analyzes the characteristies of twinning in the two types of metals by Schmid factor calculation.In addition,the relation of twinning and shear banding, as well as their influence on properties are discussed.

  12. Study on Commercial Application of FP-DSN Sulfur Transfer Additive in FCC Unit

    Institute of Scientific and Technical Information of China (English)

    Gao Siming; Han Rongxian; Chen Desheng

    2009-01-01

    The FCC unit with addition of various inventories of the FP-DSN type sulfur transfer additive was tested in a commercial scale. The effect of the sulfur transfer additive was analyzed by investigating the indicators related with the regenerator flue gas composition, the dry gas composition before desulfurization, the LPG composition before desulfurization, the acid gas, and the yield of gasoline and diesel. The test results indicated that the sulfur was trans-ferred fi'om the feed stream into the dry gas, LPG and acid gas, and the sulfur transfer effect was obvious only when the inventory of sulfur transfer additive exceeded over 2.0% of total FCC catalyst inventory.

  13. A novel potential: the interlayer potential for the fcc (111) plane family.

    Science.gov (United States)

    Tian, Fu-Yang; Chen, Nan-Xian; Shen, Jiang; Vitos, Levente

    2012-02-01

    We propose a novel interlayer potential, which is different from usual interatomic potentials. The interlayer potential represents the interaction between atomic layers in a layered material. Based on the Chen-Möbius inversion method in combination with ab initio calculations, the interlayer interactions are obtained for the face centered cubic (fcc) (111) planes. In order to check the validity of our interlayer potential, we calculate the intrinsic stacking fault energy (γ(sf)) and the surface energy (γ(s)) of five metals: Al, Ni, Cu, Ag and Au. The predicted γ(sf) and γ(s) values are compared with the theoretical results obtained from direct calculations and also with the available experimental data. Using the interlayer potentials, we also investigate the phonon dispersion and phonon density of state in the fcc (111) plane family of the considered metals.

  14. Geometry and space-time extent of pion emission region at FCC energies

    CERN Document Server

    Okorokov, V A

    2016-01-01

    The energy dependence is investigated for a wide set of space-time characteristics derived from Bose - Einstein correlations of secondary pion pairs produced in proton-proton and nucleus-nucleus interactions. Analytic functions suggested for smooth approximations of energy dependence of emission region parameters demonstrate reasonable agreement with all available experimental results for proton-proton collisions while the approximations correspond to the most of experimental data for nucleus-nucleus collisions at energies above 5 GeV. Estimations for wide set of space-time quantities are obtained for energies of various mode for the Future Circular Collider (FCC) project based on the smooth approximations. The space particle densities at freeze-out are derived also from estimations for volume of emission region and for total multiplicity at FCC energies. Estimations for charged particle density and its critical value allow the possibility of lasing behavior for secondary pions in nucleus-nucleus collisions a...

  15. A Novel FCC Catalyst Based on a Porous Composite Material Synthesized via an In Situ Technique

    Directory of Open Access Journals (Sweden)

    Shu-Qin Zheng

    2015-11-01

    Full Text Available To overcome diffusion limitations and improve transport in microporous zeolite, the materials with a wide-pore structure have been developed. In this paper, composite microspheres with hierarchical porous structure were synthesized by an in situ technique using sepiolite, kaolin and pseudoboehmite as raw material. A novel fluid catalytic cracking (FCC catalyst for maximizing light oil yield was prepared based on the composite materials. The catalyst was characterized by XRD, FT-IR, SEM, nitrogen adsorption-desorption techniques and tested in a bench FCC unit. The results indicated that the catalyst had more meso- and macropores and more acid sites than the reference catalyst, and thus can increase light oil yield by 1.31 %, while exhibiting better gasoline and coke selectivity.

  16. 馏分切割在 FCC 汽油吸附脱硫中的应用%APPLICATION OF FRACTION CUTTING METHODS IN FCC GASOLINE ADSORPTION DESULFURIZATION

    Institute of Scientific and Technical Information of China (English)

    祖运; 范跃超; 秦玉才; 宋丽娟

    2016-01-01

    采用轻重馏分切割、温度点切割及等体积切割方法对 FCC 汽油进行切割,运用改性 Y 分子筛[NiY,Cu(Ⅰ)Y,CeY]吸附剂对汽油馏分进行吸附脱硫性能考察,并联合微库仑技术和色谱-硫化物发光检测(GC-SCD)偶联技术分析切割后各馏分中硫化物的脱除情况。结果表明:NiY,Cu(Ⅰ)Y,CeY 中 B 酸和 L 酸的类型和强度决定催化剂对不同馏分的脱硫性能;NiY 中的弱 B 酸和弱 L 酸中心对芳烃含量低的馏分有较好的脱硫性能,CeY 中的强 B 酸和弱 L 酸中心对烯烃少的馏分有较好的脱硫性能,而 Cu(Ⅰ)Y 中的强 B 酸和强 L酸中心对各馏分的脱硫性能均较差;在等体积切割方法中,采用 NiY 对前段馏分、CeY 对后段馏分进行吸附脱硫,可以将 FCC 汽油的脱硫率较单一吸附剂提高47.54百分点和22.40百分点。%The performances of modified Y zeolites(Cu(Ⅰ)Y,CeY,NiY)for selective adsorption desulfurization of FCC gasoline were investigated. The FCC gasoline was cut into different fractions ac-cording to three methods:two fractions of light and heavy,temperature point cutting and constant vol-ume cutting. At the same time,the sulfur content in each fraction before and after adsorption was ana-lyzed by microcoulometry and GC-SCD techniques. The results indicate that the type and intensity of Brönsted acid on Lewis acid on the NiY,Cu(Ⅰ)Y and CeY zeolites determine the desulfurization extent of the cutting fractions. The weak Brönsted acid and the weak Lewis acid on the NiY have a higher des-ulfurization performance for low aromatic fractions;the strong Brönsted acid and the weak Lewis acid in the CeY have a better desulfurization performance for low olefin fractions. However,the strong Brönsted acid and strong acid Lewis in the Cu(Ⅰ)Y has a poorer desulfurization performance for all cut-ting fractions. In equivoluminal cutting method,the combination use of NiY for

  17. Analysis of FCC sheet metal forming with rate-independent polycrystalline plasticity FEM

    Institute of Scientific and Technical Information of China (English)

    张少睿; 李大永; 罗应兵; 彭颖红

    2004-01-01

    A rate-independent polycrystalline plasticity constitutive model considering self and latent hardening was developed. Next, a new orientation probability assignment method was proposed and the crystal orientations were assigned to Ft integration points, which represent crystals and can rotate individually. Then cup drawing of FCC aluminum sheet was studied using crystalline plasticity finite element analysis. The results show that the validity of nealing aluminum sheet, due to the balance between two main textures, the flange earing tendency is not obvious.

  18. Selective Hydrogen Transfer Reaction in FCC Process:Characterization and Application

    Institute of Scientific and Technical Information of China (English)

    Chen Beiyan; He Mingyuan; Da Zhijian

    2003-01-01

    The product distribution and gasoline quality of FCC process, especially the olefin content,heavily depends on the catalyst performance in terms of selective/non-selective hydrogen transfer reaction selectivity. A reliable experimental protocol has been established by using n-dodecane as a probe molecule to characterize the selective hydrogen transfer ability of catalytic materials. The results obtained have been correlated with the performance of the practical catalysts.

  19. Simulation of dimer diffusion on metal fcc (001)surfaces by molecular dynamics

    Institute of Scientific and Technical Information of China (English)

    LIU; Qingwei; ZHUANG; Jun

    2004-01-01

    We study systematically the dimer diffusion on metal fcc (001) surfaces through molecular dynamics calculations based on embedded atom method. Besides the conventional hopping and exchange mechanisms, some other interesting diffusion mechanisms are observed, such as the exchange rotation mechanism, the cooperative hopping mechanism, and the cooperative exchange mechanism. On the different kinds of metal surfaces, we find that not only the dominant diffusion mechanism but also the physical model for the exchange mechanism is different.

  20. First Evaluation of Dynamic Aperture at Injection for FCC-hh

    CERN Document Server

    Dalena, Barbara; Chancé, Antoine; Holzer, Bernhard; Martin, Roman; Payet, Jacques; Schulte, Daniel

    2016-01-01

    In the hadron machine option, proposed in the context of the Future Circular Colliders (FCC) study, the dipole field quality is expected to play an important role, as in the LHC. A preliminary evaluation of the field quality of dipoles, based on the Nb3Sn technology, has been provided by the magnet group. The effect of these field imperfections on the dynamic aperture, using the present lattice design, is presented and first tolerances on the main multipole components are evaluated.

  1. Preliminary Study on Reducing Olefin Content of FCC Gasoline over Cracking Catalyst

    Institute of Scientific and Technical Information of China (English)

    梁咏梅; 杨海峰; 刘耀芳; 徐春明

    2003-01-01

    Using fixed bed micro-reactor and cracking catalyst, re-cracking of fluid catalytic cracking (FCC) gasoline at lower temperature than conventional cracking condition has been studied. The results reveal that at lower temperature from 350℃-450℃ and catalyst to feed ratio of 3, the olefin content is reduced from 49% to 27%(by mass) over the catalyst whose micro-reacting activation index is 53, and the octane number is kept on high level.

  2. Split feed injection: Another tool for increasing FCC light olefin yields and gasoline octanes

    Energy Technology Data Exchange (ETDEWEB)

    Krishna, A.S. (Chevron U.S.A., El Segundo, CA (United States)); Skocpol, R.C. (Chevron Research and Technology Co., Richmond, CA (United States)); English, A.R. (Chevron U.S.A., Philadelphia, PA (United States)); Sadeghbeigi, R. (BP Oil Co., Houston, TX (United States))

    1994-01-01

    Split Feed Injection (SFI) is Chevron's patented technology for increasing the flexibility of fluid catalytic cracking units. The process improvement, which requires a relatively simple, low-cost hardware modification, results in conversion of a portion of the gasoline into lighter products (primarily olefins), and higher gasoline research and motor octanes. The technology has been extensively tested in Chevron Research Technology Company's pilot plants, and in two commercial FCC units; additional commercial tests are planned.

  3. Geometry and Space-Time Extent of Pion Emission Region at FCC Energies

    Directory of Open Access Journals (Sweden)

    V. A. Okorokov

    2016-01-01

    Full Text Available The energy dependence is investigated for a wide set of space-time characteristics derived from Bose–Einstein correlations of secondary pion pairs produced in proton-proton and nucleus-nucleus interactions. Analytic functions suggested for smooth approximations of the energy dependence of emission region parameters demonstrate reasonable agreement with all available experimental results for proton-proton collisions while the approximations correspond to most of experimental data for nucleus-nucleus collisions at energies above 5 GeV. Estimations for a wide set of space-time quantities are obtained for energies for the Future Circular Collider (FCC project based on the smooth approximations. The space particle densities at freeze-out are derived also from estimations for the volume of the emission region and for total multiplicity at FCC energies. Estimations for charged particle density and its critical value allow the possibility of lasing behavior for secondary pions in nucleus-nucleus collisions at FCC energy. The mathematical formalism is presented for study of the peak shape of correlation function for general case of central-symmetrical Lévy–Feldheim distribution.

  4. Effect of Olefins on Formation of Sulfur Compounds in FCC Gasoline

    Institute of Scientific and Technical Information of China (English)

    Tang Jinlian; Xu Youhao; Gong Jianhong; Wang Xieqing

    2008-01-01

    The effect of olefins on formation of sulfur compounds in FCC gasoline was studied in a small-scale fixed fluidized bed (FFB) unit at temperatures ranging from 400℃ to 500℃, a weight hourly space velocity (WHSV) of 10 h-1, and a catalyst/oil ratio of 6. The results showed that C4-C6 olefins contained in the FCC gasoline could react with H2S to form predominantly thiophenes, alkyl-thiophenes as well as a fractional amount of thiols, while large molecular olefins such as heptene could react with hydrogen sulfide to form benzothiophenes. The amount of sulfur compounds formed at different tem-peratures over different catalysts were in proportion to the mass fractions of olefins in the feedstock,with the amount of sulfur compounds formed over REUSY catalyst exceeding those formed over the shape selective zeolite catalyst owing to the effect of catalyst performance and the impact of catalyst on the degree of olefin conversion. The amount of sulfur compounds generated and their increase reached a maximum at 450℃ and a minimum at 400℃ because of the influence of temperature on the thermody-namic and kinetic constants for formation of sulfur compound as well as on the olefin conversion degree.Based on the above-mentioned study, a reaction network and a model for prediction of sulfur com-pounds generated upon reaction of olefins in FCC gasoline with H2S were established.

  5. Formation of Superlattices of Gold Nanoparticles Using Ostwald Ripening in Emulsions: Transition from fcc to bcc Structure.

    Science.gov (United States)

    Schmitt, Julien; Hajiw, Stéphanie; Lecchi, Amélie; Degrouard, Jéril; Salonen, Anniina; Impéror-Clerc, Marianne; Pansu, Brigitte

    2016-06-30

    An efficient method to form 3D superlattices of gold nanoparticles inside oil emulsion droplets is presented. We demonstrate that this method relies on Ostwald ripening, a well-known phenomenon occurring during the aging of emulsions. The key point is that the nanoparticle concentration inside the smaller droplets is increasing very slowly with time, thus inducing the crystallization of the nanoparticles into superlattices. Using oil-in-water emulsions doped with hydrophobic gold nanoparticles, we demonstrate that this method is efficient for different types of oils (toluene, cyclohexane, dodecane, and hexadecane). 3D superlattices of the nanoparticles are obtained, with dimensions reaching a hundred nanometers. The kinetics of the crystallization depends on the solubility of the oil in water but also on the initial concentration of the gold nanoparticles in oil. This method also provides an innovative way to obtain the complete phase diagram of nanoparticle suspensions with concentration. Indeed, during this slow crystallization process, a transition from a disordered suspension to a fcc structure is observed, followed by a transition toward a bcc structure. This evolution with time provides key results to understand the role played by the ligands located at the surface of the nanoparticles in order to control the type of superlattices which are formed.

  6. Cellular Phone Towers, FCC registered communications towers. Points were generated from FCC data latlong. Originally created as a basis of comparison for Appraiser's cell tower points, bu comparison was inconclusive. Represented all registered FCC sites as of 6/26/2003. No, Published in 2003, 1:1200 (1in=100ft) scale, Sedgwick County, Kansas.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Cellular Phone Towers dataset, published at 1:1200 (1in=100ft) scale, was produced all or in part from Other information as of 2003. It is described as 'FCC...

  7. Nucleation of the diamond phase in aluminium-solid solutions

    Science.gov (United States)

    Hornbogen, E.; Mukhopadhyay, A. K.; Starke, E. A., Jr.

    1993-01-01

    Precipitation was studied from fcc solid solutions with silicon, germanium, copper and magnesium. Of all these elements only silicon and germanium form diamond cubic (DC) precipitates in fcc Al. Nucleation of the DC structure is enhanced if both types of atom are dissolved in the fcc lattice. This is interpreted as due to atomic size effects in the prenucleation stage. There are two modes of interference of fourth elements with nucleation of the DC phase in Al + Si, Ge. The formation of the DC phase is hardly affected if the atoms (for example, copper) are rejected from the (Si, Ge)-rich clusters. If additional types of atom are attracted by silicon and/or germanium, DC nuclei are replaced by intermetallic compounds (for example Mg2Si).

  8. Nanoscale heterogeneity, premartensitic nucleation, and a new plutonium structure in metastable δ fcc Pu-Ga alloys

    Science.gov (United States)

    Conradson, Steven D.; Bock, Nicolas; Castro, Julio M.; Conradson, Dylan R.; Cox, Lawrence E.; Dmowski, Wojciech; Dooley, David E.; Egami, Takeshi; Espinosa-Faller, Francisco J.; Freibert, Franz J.; Garcia-Adeva, Angel J.; Hess, Nancy J.; Holmström, Erik K.; Howell, Rafael C.; Katz, Barbara; Lashley, Jason C.; Martinez, Raymond J.; Moore, David P.; Morales, Luis A.; Olivas, J. David; Pereyra, Ramiro A.; Ramos, Michael; Rudin, Sven P.; Villella, Phillip M.

    2014-06-01

    The scientifically fascinating question of the spatial extent and bonding of the 5f orbitals of Pu and its six different phases extends to its δ-retained alloys and the mechanism by which Ga and a number of other unrelated elements stabilize its low density face-centered-cubic (fcc) structure. This issue of phase stability is also important technologically because of its significance to Science-Based Stockpile Stewardship. Answering these questions requires information on the local order and structure around the Ga and its effects on the Pu. We have addressed this by characterizing the structures of a large number of Pu-Ga and two Pu-In and one Pu-Ce δ alloys, including a set of high purity δ Pu1-xGax materials with 1.7 ≤ x ≤ 6.4 at. % Ga that span the low [Ga] portion of the δ region of the phase diagram across the ˜3.3 at. % Ga metastability boundary, with extended x-ray absorption fine structure (EXAFS) spectroscopy that probes the element specific local structure, supplemented by x-ray pair distribution function analysis that gives the total local structure to longer distances, and x-ray diffraction that gives the long-range average structure of the periodic component of the materials. Detailed analyses indicate that the alloys at and below a nominal composition of ˜3.3 at. % Ga are heterogeneous and in addition to the δ phase also contain up to ˜20% of a novel, coexisting "σ" structure for Pu that forms in nanometer scale domains that are locally depleted in Ga. The invariance of the Ga EXAFS with composition indicates that this σ structure forms in Ga-depleted domains that result from the Ga atoms in the δ phase self-organizing into a quasi-intermetallic with a stoichiometry of Pu25-35Ga so that δ Pu-Ga is neither a random solid solution nor the more stable Pu3Ga + α. Above this 3.3 at. % Ga nominal composition, the δ Pu-Ga alloy is homogeneous, and no σ phase is present. These results that demonstrate that collective and cooperative

  9. Sequence determination of exp-1 Gene of Plasmodium Falciparum Isolate FCC1/HN(英文)%Sequence determination of exp-1 Gene of Plasmodium Falciparum Isolate FCC1/HN

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    目的测定恶性疟原虫FCC1/HN株exp-1基因序列.方法根据exp-1基因已知序列设计合成1对引物,用PCB技术从FCC1/HN株基因组DNA中扩增exp-1基因;将exp-1基因克隆入pMD-18T载体,转化大肠杆菌JM109感受态细胞,铺x-gal LB平板;挑取阳性茵落,用酶切,PCR扩增进行鉴定.以正确的重组质粒为模板,用双脱氧链末端终止法测定exp-1基因序列.结果从恶性疟原虫FCC1/HN株基因组DNA中获取exp-1基因,成功克隆入pMD-18T载体;测序表明FCC1/HN株exp-1基因全长937bp,编码162个氨基酸.结论克隆了恶性疟原虫FCC1/HN株exp-1基因,并测定了其核苷酸序列,为进一步研究其功能奠定基础.%Objective To determine the sequence of exported protein 1 (exp-1 )gene of Plasmodium falciparum ( P. F ) isolate FCC1/HN. Methods According to the known sequence of a pair of primers were designed and synthesized. The exp-1 gene was amplified by polymerase chain reaction (PCR)from genomic DNA of isolate FCC1/HN and cloned into the pMD-18T vector. Then the recombinant plasmid pT-exp-1 was transformed into E. Coli JM109. The positive clones were screened and identified by agarose gel electrophoresis , endonuclease digestion and PCR technique. The correct recombinant plasmid pT-exp-1 was used as template , and the nucleotide sequence of exp-1 gene was determined by the dideoxy chain termination method. Results The exp-I gene from genomic DNA of P. Falcipamm isolate FCC1/HN was specifically amplified, and the correct recombinant plasmid pT-exp-1 was constructed .The full length of exp-1 gene of isolate FCC1/HN, encoding 162 amino acids , is 937 base pairs . Conclusion The exp-1 gene of P. Falciparum was cloned and sequenced , and a foundation was laid for further study on the function of exp-1 gene.

  10. 47 CFR 95.423 - (CB Rule 23) What must I do if the FCC tells me that my CB station is causing interference?

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false (CB Rule 23) What must I do if the FCC tells me...) Radio Service Other Things You Need to Know § 95.423 (CB Rule 23) What must I do if the FCC tells me that my CB station is causing interference? (a) If the FCC tells you that your CB station is...

  11. 47 CFR 95.220 - (R/C Rules 20) What must I do if the FCC tells me that my R/C station is causing interference?

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false (R/C Rules 20) What must I do if the FCC tells.../C) Radio Service Other Things You Need to Know § 95.220 (R/C Rules 20) What must I do if the FCC tells me that my R/C station is causing interference? (a) If the FCC tells you that your R/C station...

  12. TEMPERATURE DEPENDENCES OF ATOM STATES AND PHYSICAL PROPERTIES OF fcc-, METASTABLE hcp- AND bcc- Cu%fcc-,亚稳hcp-和bcc-Cu的原子状态及物理性质随温度的变化关系

    Institute of Scientific and Technical Information of China (English)

    陶辉锦; 谢佑卿; 彭红建; 余方新; 刘锐锋; 李晓波

    2006-01-01

    结合纯金属单原子(OA)理论和Debye-Grüneisen模型,采用CALPHAD方法确定的晶格稳定参数,研究了SGTE纯单质数据库中fcc-,hcp-和bcc-Cu的原子状态及物理性质(原子势能、原子动能、原子体积、体弹性模量和热膨胀系数等)随温度的变化关系.结果表明:电子结构计算结果与第一原理方法非常接近.3种晶体结构的电子结构差别不大,单键半径非常接近.原子体积顺序为:Va(bcc)>Va(hcp)>Va(fcc);共价电子浓度顺序为:nc(fcc)>nc(hcp)>nc(bcc);原子势能大小顺序为:εp(fcc)<εp(hcp)<εp(bcc);晶格稳定性顺序为:△G(fcc)>△G(hcp)>△G(bcc).原子动能随温度的增加幅度约为势能的3-4倍.

  13. Analysis of phase formation in multi-component alloys

    Energy Technology Data Exchange (ETDEWEB)

    Raghavan, R.; Hari Kumar, K.C. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai (India); Murty, B.S., E-mail: murty@iitm.ac.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai (India)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer CALPHAD approach appears to predict BCC phase formation more accurately than FCC phase formation. Black-Right-Pointing-Pointer Solid solution is favored when the {Delta}S{sub config}/{Delta}S{sub fusion} > 1 for equiatomic alloys. Black-Right-Pointing-Pointer Solid solution is favored when the {Delta}S{sub config}/{Delta}S{sub fusion} > 1.2 for non-equiatomic alloys. Black-Right-Pointing-Pointer BCC phase is favored when atomic size difference is larger, as reflected by a higher value of {Delta}S{sub {sigma}}/k. Black-Right-Pointing-Pointer FCC and BCC phase formation appears to be governed mainly by {Delta}H{sub mix} and {Delta}S{sub {sigma}}/k, respectively. - Abstract: An attempt has been made to predict phase formation using a CALPHAD-based approach for a large number of compositions that are known to form FCC, BCC and a mixture of FCC and BCC phases. The stable phase is assumed to be the first phase that is formed upon cooling from liquid state with the highest driving force. The driving force for other phases at the transition for various compositions is also presented. A comparison between the parametric approach of phase prediction by study of thermodynamic and topological parameters on one hand and the CALPHAD approach on the other is also presented. CALPHAD approach appears to predict BCC phase formation much more accurately than the FCC phase formation. The results indicate that solid solution formation in multicomponent alloys is favored when the ratio of {Delta}S{sub config}/{Delta}S{sub fusion} is greater than 1 and 1.2 for equiatomic and non-equiatomic alloys, respectively. The results also point out that BCC phase is favored when the atomic size difference is larger, which is reflected by a higher value of {Delta}S{sub {sigma}}/k. Formation of FCC phase appears to be governed mainly by {Delta}H{sub mix}, while BCC phase governed by {Delta}S{sub {sigma}}/k, which is representative of strain in the structure.

  14. Synthesis of 4H/fcc-Au@M (M = Ir, Os, IrOs) Core-Shell Nanoribbons For Electrocatalytic Oxygen Evolution Reaction.

    Science.gov (United States)

    Fan, Zhanxi; Luo, Zhimin; Chen, Ye; Wang, Jie; Li, Bing; Zong, Yun; Zhang, Hua

    2016-08-01

    The high-yield synthesis of 4H/face-centered cubic (fcc)-Au@Ir core-shell nanoribbons (NRBs) is achieved via the direct growth of Ir on 4H Au NRBs under ambient conditions. Importantly, this method can be used to synthesize 4H/fcc-Au@Os and 4H/fcc-Au@IrOs core-shell NRBs. Significantly, the obtained 4H/fcc-Au@Ir core-shell NRBs demonstrate an exceptional electrocatalytic activity toward the oxygen evolution reaction under acidic condition, which is much higher than that of the commercial Ir/C catalyst.

  15. Proceedings, High-Precision $\\alpha_s$ Measurements from LHC to FCC-ee

    Energy Technology Data Exchange (ETDEWEB)

    d' Enterria, David [CERN; Skands, Peter Z. [Monash U.

    2015-01-01

    This document provides a writeup of all contributions to the workshop on "High precision measurements of $\\alpha_s$: From LHC to FCC-ee" held at CERN, Oct. 12--13, 2015. The workshop explored in depth the latest developments on the determination of the QCD coupling $\\alpha_s$ from 15 methods where high precision measurements are (or will be) available. Those include low-energy observables: (i) lattice QCD, (ii) pion decay factor, (iii) quarkonia and (iv) $\\tau$ decays, (v) soft parton-to-hadron fragmentation functions, as well as high-energy observables: (vi) global fits of parton distribution functions, (vii) hard parton-to-hadron fragmentation functions, (viii) jets in $e^\\pm$p DIS and $\\gamma$-p photoproduction, (ix) photon structure function in $\\gamma$-$\\gamma$, (x) event shapes and (xi) jet cross sections in $e^+e^-$ collisions, (xii) W boson and (xiii) Z boson decays, and (xiv) jets and (xv) top-quark cross sections in proton-(anti)proton collisions. The current status of the theoretical and experimental uncertainties associated to each extraction method, the improvements expected from LHC data in the coming years, and future perspectives achievable in $e^+e^-$ collisions at the Future Circular Collider (FCC-ee) with $\\cal{O}$(1--100 ab$^{-1}$) integrated luminosities yielding 10$^{12}$ Z bosons and jets, and 10$^{8}$ W bosons and $\\tau$ leptons, are thoroughly reviewed. The current uncertainty of the (preliminary) 2015 strong coupling world-average value, $\\alpha_s(m_Z)$ = 0.1177 $\\pm$ 0.0013, is about 1\\%. Some participants believed this may be reduced by a factor of three in the near future by including novel high-precision observables, although this opinion was not universally shared. At the FCC-ee facility, a factor of ten reduction in the $\\alpha_s$ uncertainty should be possible, mostly thanks to the huge Z and W data samples available.

  16. Radiation Load Optimization in the Final Focus System of FCC-hh

    CERN Document Server

    Martin, Roman; Cerutti, Francesco; Tomás, Rogelio

    2016-01-01

    With a center-of-mass energy of up to 100 TeV, FCC-hh will produce highly energetic collision debris at the Interaction Point (IP). Protecting the final focus quadrupoles from this radiation is challenging, since the required amount of shielding placed inside the magnets will reduce the free aperture, thereby limiting the β^{*} reach and luminosity. Hence, radiation mitigation strategies that make best use of the available aperture are required. In this paper, we study the possibility to split the first quadrupole Q1 into two quadrupoles with individual apertures, in order to distribute the radiation load more evenly and reduce the peak dose.

  17. Grain size and film thickness effect on the thermal expansion coefficient of FCC metallic thin films.

    Science.gov (United States)

    Hwang, Seulgi; Kim, Youngman

    2011-08-01

    Thin films are used in wide range of applications in industry, such as solar cells and LEDs. When thin films are deposited on substrates, various stresses are generated due to the mechanical difference between the film and substrate. These stresses can cause defects, such as cracking and buckling. Therefore, knowledge of the mechanical properties is important for improving their reliability and stability. In this study, the thermal expansion coefficient of FCC metallic thin films, such as Ag and Cu, which have different grain sizes and thicknesses, were calculated using the thermal cycling method. As a result, thermal expansion coefficient increased with increasing grain size. However, the film thickness had no remarkable effect.

  18. Electronic Structure of the fcc Transition Metals Ir, Rh, Pt, and Pd

    DEFF Research Database (Denmark)

    Andersen, O. Krogh

    1970-01-01

    /atom)/Ry, respectively. Spin-orbit coupling is important for all four metals and the coupling parameter varies by 30% over the d bandwidth. Detailed comparisons with de Haas—van Alphen Fermi-surface dimensions have previously been presented and the agreement was very good. Comparison with measured electronic specific......We give a complete description of a relativistic augmented-plane-wave calculation of the band structures of the paramagnetic fcc transition metals Ir, Rh, Pt, and Pd. The width and position of the d band decrease in the sequence Ir, Pt, Rh, Pd; and N(EF)=13.8,23.2,18.7, and 32.7 (states...

  19. First Considerations on Beam Optics and Lattice Design for the Future Hadron-Hadron Collider FCC

    CERN Document Server

    Alemany Fernandez, R

    2014-01-01

    The present document explains the steps carried out in order to make the first design of the Future Hadron-Hadron Collider (FCC-hh) following the base line parameters that can be found in [1]. Two lattice layouts are presented, a ring collider with 12 arcs and 12 straight sections, four of them designed as interaction points, and a racetrack like collider with two arcs and two straight sections, each of them equipped with two interaction points. The lattice design presented in the paper is modular allowing the same modules be used for both layouts. The present document addresses as well the beta star reach at the interaction points.

  20. Understanding Anharmonicity in fcc Materials: From its Origin to ab initio Strategies beyond the Quasiharmonic Approximation.

    Science.gov (United States)

    Glensk, A; Grabowski, B; Hickel, T; Neugebauer, J

    2015-05-15

    We derive the Gibbs energy including the anharmonic contribution due to phonon-phonon interactions for an extensive set of unary fcc metals (Al, Ag, Au, Cu, Ir, Ni, Pb, Pd, Pt, Rh) by combining density-functional-theory (DFT) calculations with efficient statistical sampling approaches. We show that the anharmonicity of the macroscopic system can be traced back to the anharmonicity in local pairwise interactions. Using this insight, we derive and benchmark a highly efficient approach which allows the computation of anharmonic contributions using a few T=0 K DFT calculations only.

  1. Dynamic stability of fcc crystals under isotropic loading from first principles.

    Science.gov (United States)

    Rehák, Petr; Cerný, Miroslav; Pokluda, Jaroslav

    2012-05-30

    Lattice dynamics and stability of four fcc crystals (Al, Ir, Pt and Au) under isotropic (hydrostatic) tensile loading are studied from first principles using the linear response method and the harmonic approximation. The results reveal that, contrary to former expectations, strengths of all the studied crystals are limited by instabilities related to soft phonons with finite or vanishing wavevectors. The critical strains associated with such instabilities are remarkably lower than those related to the volumetric instability. On the other hand, the corresponding reduction of the tensile strength is by 20% at the most. An analysis of elastic stability conditions is also performed and the results obtained by means of both approaches are compared.

  2. Numerical evidence for bcc ordering at the surface of a critical fcc nucleus

    OpenAIRE

    Wolde, P.R. ten; Ruiz-Montero, M. J.; Frenkel, D.

    1995-01-01

    We report a computer-simulation study of the crystal nucleation barrier and the structure of crystal nuclei in a Lennard-Jones system at moderate supercooling. The stable structure of the Lennard-Jones solid is known to be face-centered cubic. We find that the precritical nuclei are predominantly body-centered cubic ordered. But, as the nucleus grows to its critical size, the core becomes fcc ordered. Surprisingly, however, the interface of the critical nucleus retains a high degree of bcc-li...

  3. Two Types of Novel Feedstock Injection Structures of the FCC Riser Reactor

    Institute of Scientific and Technical Information of China (English)

    范怡平; 蔡飞鹏; 时铭显; 徐春明

    2004-01-01

    Based on the analysis of flow characteristics of the FCC riser feedstock injection zone, two novel feedstock injection structures are put forward. By investigating three flow parameters in the feedstock injection zone under the three different structures (the traditional and the novel No. 1, No. 2 structures): the local density, the particle backmixng ratio, and the jet eigen-concentration, the flow feature under three structures were obtained. The experimental results demonstrate that the flow features under both proposed structures are obviously improved comparing with those under the traditional structure. Especially, the performance of the deflector-structured No. 2 is more desirable than that of No. 1.

  4. First Evaluation of Dynamic Aperture at Injection for FCC-hh

    CERN Document Server

    Dalena, B; Chancé, A; Holzer, B; Schulte, D

    2016-01-01

    In the Hadron machine option, proposed in the context of the Future Circular Colliders (FCC) study, the dipole field quality is expected to play an important role, as in the LHC. A preliminary evaluation of the field quality of dipoles, based on the Nb$_{3}$Sn technology, has been provided by the magnet group. The effect of these field imperfections on the dynamic aperture, using the present lattice design, is presented and first tolerances on the b$_3$ and b$_5$ multipole components are evaluated.

  5. Magnetic phase diagrams from non-collinear canonical band theory

    DEFF Research Database (Denmark)

    Shallcross, Sam; Nordstrom, L.; Sharma, S.

    2007-01-01

    to construct phase diagrams of magnetic order for the fcc and bcc lattices. Several examples of non-collinear magnetism are seen to be canonical in origin, in particular, that of gamma-Fe. In this approach, the determination of magnetic stability results solely from changes in kinetic energy due to spin...

  6. Surface modification-induced phase transformation of hexagonal close-packed gold square sheets

    KAUST Repository

    Fan, Zhanxi

    2015-03-13

    Conventionally, the phase transformation of inorganic nanocrystals is realized under extreme conditions (for example, high temperature or high pressure). Here we report the complete phase transformation of Au square sheets (AuSSs) from hexagonal close-packed (hcp) to face-centered cubic (fcc) structures at ambient conditions via surface ligand exchange, resulting in the formation of (100)f-oriented fcc AuSSs. Importantly, the phase transformation can also be realized through the coating of a thin metal film (for example, Ag) on hcp AuSSs. Depending on the surfactants used during the metal coating process, two transformation pathways are observed, leading to the formation of (100)f-oriented fcc Au@Ag core-shell square sheets and (110)h/(101)f-oriented hcp/fcc mixed Au@Ag nanosheets. Furthermore, monochromated electron energy loss spectroscopy reveals the strong surface plasmon resonance absorption of fcc AuSS and Au@Ag square sheet in the infrared region. Our findings may offer a new route for the crystal-phase and shape-controlled synthesis of inorganic nanocrystals. © 2015 Macmillan Publishers Limited. All rights reserved.

  7. Ambient stable tetragonal and orthorhombic phases in penta-twinned bipyramidal au microcrystals.

    Science.gov (United States)

    Mettela, Gangaiah; Bhogra, Meha; Waghmare, Umesh V; Kulkarni, Giridhar U

    2015-03-04

    Face-centered cubic (fcc) lattice is the only known crystal structure of bulk gold. In the present work, we report the presence of body-centered tetragonal (bct) and body-centered orthorhombic (bco) phases in bipyramidal Au microcrystals with penta-twinned tips. These microcrystals have been obtained by thermolysis of (AuCl4)(-) stabilized with tetraoctylammonium bromide (ToABr) in air at about 220 °C for 30 min. Using a laboratory monochromatic X-ray source, the non-fcc phases could be readily detected. The remarkable occurrence of non-fcc phases of Au grown in the temperature window of 200-250 °C results from the geometrically induced strains in the bipyramids. Having derived first-principles theoretical support for the temperature-dependent stability of non-fcc Au structures under stress, we identify its origin in soft modes. Annealing at high temperatures relieves the stress, thus destabilizing the non-fcc phases.

  8. LatticeLibrary and BccFccRaycaster: Software for processing and viewing 3D data on optimal sampling lattices

    Directory of Open Access Journals (Sweden)

    Elisabeth Schold Linnér

    2016-01-01

    Full Text Available In this paper, we present LatticeLibrary, a C++ library for general processing of 2D and 3D images sampled on arbitrary lattices. The current implementation supports the Cartesian Cubic (CC, Body-Centered Cubic (BCC and Face-Centered Cubic (FCC lattices, and is designed to facilitate addition of other sampling lattices. We also introduce BccFccRaycaster, a plugin for the existing volume renderer Voreen, making it possible to view CC, BCC and FCC data, using different interpolation methods, with the same application. The plugin supports nearest neighbor and trilinear interpolation at interactive frame rates. These tools will enable further studies of the possible advantages of non-Cartesian lattices in a wide range of research areas.

  9. LatticeLibrary and BccFccRaycaster: Software for processing and viewing 3D data on optimal sampling lattices

    Science.gov (United States)

    Linnér, Elisabeth Schold; Morén, Max; Smed, Karl-Oskar; Nysjö, Johan; Strand, Robin

    In this paper, we present LatticeLibrary, a C++ library for general processing of 2D and 3D images sampled on arbitrary lattices. The current implementation supports the Cartesian Cubic (CC), Body-Centered Cubic (BCC) and Face-Centered Cubic (FCC) lattices, and is designed to facilitate addition of other sampling lattices. We also introduce BccFccRaycaster, a plugin for the existing volume renderer Voreen, making it possible to view CC, BCC and FCC data, using different interpolation methods, with the same application. The plugin supports nearest neighbor and trilinear interpolation at interactive frame rates. These tools will enable further studies of the possible advantages of non-Cartesian lattices in a wide range of research areas.

  10. Modulating fcc and hcp Ruthenium on the Surface of Palladium-Copper Alloy through Tunable Lattice Mismatch.

    Science.gov (United States)

    Yao, Yancai; He, Dong Sheng; Lin, Yue; Feng, Xiaoqian; Wang, Xin; Yin, Peiqun; Hong, Xun; Zhou, Gang; Wu, Yuen; Li, Yadong

    2016-04-25

    Herein, we report an epitaxial-growth-mediated method to grow face-centered cubic (fcc) Ru, which is thermodynamically unfavorable in the bulk form, on the surface of Pd-Cu alloy. Induced by the galvanic replacement between Ru and Pd-Cu alloy, a shape transformation from a Pd-Cu@Ru core-shell to a yolk-shell structure was observed during the epitaxial growth. The successful coating of the unconventional crystallographic structure is critically dependent on the moderate lattice mismatch between the fcc Ru overlayer and PdCu3 alloy substrate. Further, both fcc and hexagonal close packed (hcp) Ru can be selectively grown through varying the lattice spacing of the Pd-Cu substrate. The presented findings provide a new synthetic pathway to control the crystallographic structure of metal nanomaterials.

  11. Interaction between Ni and HZSM-5 in aromatization-enhanced reactive adsorption desulfurization catalysts for FCC gasoline upgrading.

    Science.gov (United States)

    Zhao, Jinchong; Zhang, Lulu; She, Nannan; Liu, Yunqi; Chai, Yongming; Liu, Chenguang

    A compound catalyst (RA) consisted of Ni, ZnO and HZSM-5 with functions of reactive adsorption desulfurization (RADS) and olefin aromatization for fluid catalytic cracking (FCC) gasoline upgrading was prepared. X-ray powder diffraction (XRD), temperature-programmed reduction and low-temperature N2 adsorption were used to characterize the properties of the catalysts. Performance evaluation by FCC gasoline was carried out, and the result showed that the catalyst RA performed well in desulfurization and aromatization. For comparison, RADS catalyst (represented by DS) consisted of Ni and ZnO and aromatization catalyst (represented by Ar) consisted of HZSM-5 were prepared, respectively. They were combined in different ways to help investigating interaction between Ni and HZSM-5. Performance evaluated by FCC gasoline showed that catalyst RA performed best in desulfurization with a slight octane number loss. Interaction between Ni and HZSM-5 is a significant factor which influences the performance of the catalyst.

  12. Recycling polystyrene into fuels by means of FCC. Performance of various acidic catalysts

    Energy Technology Data Exchange (ETDEWEB)

    De la Puente, Gabriela; Sedran, Ulises [Instituto de Investigaciones en Catalisis y Petroquimica, INCAPE, Santiago del Estero 2654, 3000 Santa Fe (Argentina)

    1998-12-07

    In accordance with the option of recycling plastics into fuels by dissolving them in standard feedstocks for the process of catalytic cracking of hydrocarbons, FCC, various acidic catalysts (zeolites ZSM-5, mordenite, Y, and a sulfur-promoted zirconia) were tested in the conversion of polystyrene dissolved into inert benzene at 550C in a fluidized-bed batch reactor. Experiments were performed with very short contact times of up to 12s. Main products were in the gasoline range, including benzene, toluene, ethylbenzene, styrene, and minor amounts of C{sub 9-12} aromatics and light C{sub 5-} compounds. Coke was always produced in very significant amounts. All the products can be justified with basis on the properties of each catalyst and the various possible catalytic reaction pathways: cracking after protolytic attack on the polymer fragments, styrene oligomerization and subsequent cracking, or hydrogen transfer to styrene. Styrene would be mainly produced in this system from thermal cracking of the polymer as the initial step. If present, shape selectivity effects due to catalyst structure can influence significantly the prevalence of the various reactions, because they would interfere with those undergoing bulky transition states, like styrene oligomerization or hydrogen transfer. Even though sulfur-promoted zirconia is highly acidic, the low proportion of Broensted-type acid sites does not allow the occurrence of secondary styrene reactions. It was shown that most favorable product distributions (higher yields of desirable products) are obtained on equilibrium commercial FCC catalysts

  13. Symmetry-Guaranteed and Accidental Nodal-Line Semimetals in FCC Lattice

    CERN Document Server

    Kawakami, Takuto

    2016-01-01

    We demonstrate theoretically that nodal-line semimetal (NLS) states can be realized in face-center-cubic (fcc) lattice with orbits belonging to one irreducible representation, such as [$p_x$, $p_y$, $p_z$] and/or [$d_{xy}$, $d_{xz}$, $d_{yz}$]. It is shown that the three orbits are subdivided with respect to the odd- and even-parity upon mirror reflection on high symmetry planes, which yields an analytic expression for the trajectory of NL in momentum space when a tight-binding (TB) model is adopted. It becomes clear that there are two kinds of NLs, a symmetry-guaranteed one around the surface of the first Brillouin zone (BZ), and an accidental one around the BZ center governed by the hopping integrals. As a realization of the idea, we analyze the fcc photonic crystal composed of dielectric spheres by solving the Maxwell's equations. Two symmetry-guaranteed and one accidental NLS photonic states are observed. This provides a good platform to confirm experimentally the existence of topological NLS state, and o...

  14. Strength and strain rate sensitivity for hcp and fcc nanopolycrystal metals

    Indian Academy of Sciences (India)

    P Rodriguez; R W Armstrong

    2006-12-01

    While there is overwhelming evidence that strengthening from grain size refinement persists into the nanocrystalline grain size regime consistent with extrapolation of classical Hall–Petch (H–P) behaviour, there are indications of a transition to an inverse H–P dependence, i.e. grain boundary weakening behaviour, occurring below a grain size of ∼ 10–20 nm. When Hall–Petch strengthening predominates, and the stress intensity, i.e. H–P slope value, , is thermally-activated (as is the case for pure fcc and the easy basal slip hcp metals), the strain rate sensitivity, defined as [/ ln(d/d], also is predicted to follow an H–P type dependence, thus, increasing with decrease in grain size. As a consequence, the activation volume that is inversely proportional to the strain rate sensitivity, is found to decrease by an order of magnitude, from around 1000 b3 in conventional grain size fcc Cu and Ni materials to 10–100 b3, for nanomaterials. At the smallest grain sizes, the transition to an inverse H–P dependence has been proposed to occur because of onset of effective high temperature grain boundary weakening behaviour that is well known in limiting creep property descriptions. If the inverse H–P effect (grain boundary weakening) is genuine, we predict that the strain rate sensitivity and corresponding inverse activation volume dependence on grain size should also have to show a reversal.

  15. Ab initio random structure search for 13-atom clusters of fcc elements.

    Science.gov (United States)

    Chou, J P; Hsing, C R; Wei, C M; Cheng, C; Chang, C M

    2013-03-27

    The 13-atom metal clusters of fcc elements (Al, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au) were studied by density functional theory calculations. The global minima were searched for by the ab initio random structure searching method. In addition to some new lowest-energy structures for Pd13 and Au13, we found that the effective coordination numbers of the lowest-energy clusters would increase with the ratio of the dimer-to-bulk bond length. This correlation, together with the electronic structures of the lowest-energy clusters, divides the 13-atom clusters of these fcc elements into two groups (except for Au13, which prefers a two-dimensional structure due to the relativistic effect). Compact-like clusters that are composed exclusively of triangular motifs are preferred for elements without d-electrons (Al) or with (nearly) filled d-band electrons (Ni, Pd, Cu, Ag). Non-compact clusters composed mainly of square motifs connected by some triangular motifs (Rh, Ir, Pt) are favored for elements with unfilled d-band electrons.

  16. Identifying self-interstitials of bcc and fcc crystals in molecular dynamics

    Science.gov (United States)

    Bukkuru, S.; Bhardwaj, U.; Warrier, M.; Rao, A. D. P.; Valsakumar, M. C.

    2017-02-01

    Identification of self-interstitials in molecular dynamics (MD) simulations is of critical importance. There exist several criteria for identifying the self-interstitial. Most of the existing methods use an assumed cut-off value for the displacement of an atom from its lattice position to identify the self-interstitial. The results obtained are affected by the chosen cut-off value. Moreover, these chosen cut-off values are independent of temperature. We have developed a novel unsupervised learning algorithm called Max-Space Clustering (MSC) to identify an appropriate cut-off value and its dependence on temperature. This method is compared with some widely used methods such as effective sphere (ES) method and nearest neighbor sphere (NNS) method. The cut-off radius obtained using our method shows a linear variation with temperature. The value of cut-off radius and its temperature dependence is derived for five bcc (Cr, Fe, Mo, Nb, W) and six fcc (Ag, Au, Cu, Ni, Pd, Pt) crystals. It is seen that the ratio of the cut-off values "r" to the lattice constant "a" lies between 0.23 and 0.3 at 300 K and this ratio is on an average smaller for the fcc crystals. Collision cascade simulations are carried out for Primary knock-on Atom (PKA) energies of 5 keV in Fe (at 300 K and 1000 K) and W (at 300 K and 2500 K) and the results are compared using the various methods.

  17. Dislocation creation and void nucleation in FCC ductile metals under tensile loading: a general microscopic picture.

    Science.gov (United States)

    Pang, Wei-Wei; Zhang, Ping; Zhang, Guang-Cai; Xu, Ai-Guo; Zhao, Xian-Geng

    2014-11-10

    Numerous theoretical and experimental efforts have been paid to describe and understand the dislocation and void nucleation processes that are fundamental for dynamic fracture modeling of strained metals. To date an essential physical picture on the self-organized atomic collective motions during dislocation creation, as well as the essential mechanisms for the void nucleation obscured by the extreme diversity in structural configurations around the void nucleation core, is still severely lacking in literature. Here, we depict the origin of dislocation creation and void nucleation during uniaxial high strain rate tensile processes in face-centered-cubic (FCC) ductile metals. We find that the dislocations are created through three distinguished stages: (i) Flattened octahedral structures (FOSs) are randomly activated by thermal fluctuations; (ii) The double-layer defect clusters are formed by self-organized stacking of FOSs on the close-packed plane; (iii) The stacking faults are formed and the Shockley partial dislocations are created from the double-layer defect clusters. Whereas, the void nucleation is shown to follow a two-stage description. We demonstrate that our findings on the origin of dislocation creation and void nucleation are universal for a variety of FCC ductile metals with low stacking fault energies.

  18. Molecular dynamics prediction of phonon-mediated thermal conductivity of f.c.c. Cu

    Science.gov (United States)

    Evteev, Alexander V.; Momenzadeh, Leila; Levchenko, Elena V.; Belova, Irina V.; Murch, Graeme E.

    2014-03-01

    The phonon-mediated thermal conductivity of f.c.c. Cu is investigated in detail in the temperature range 40-1300 K. The calculations are performed in the framework of equilibrium molecular dynamics making use of the Green-Kubo formalism and one of the most reliable embedded-atom method potentials for Cu. It is found that the temporal decay of the heat current autocorrelation function (HCACF) of the Cu model at low and intermediate temperatures demonstrate a more complex behaviour than the two-stage decay observed previously for the f.c.c. Ar model. After the first stage of decay, it demonstrates a peak in the temperature range 40-800 K. A decomposition model of the HCACF is introduced. In the framework of that model we demonstrate that a classical description of the phonon thermal transport in the Cu model can be used down to around one quarter of the Debye temperature (about 90 K). Also, we find that above 300 K the thermal conductivity of the Cu model varies with temperature more rapidly than ?, following an exponent close to -1.4 in agreement with previous calculations on the Ar model. Phonon thermal conductivity of Cu is found to be about one order of magnitude higher than Ar. The phonon contribution to the total thermal conductivity of Cu can be estimated to be about 0.5% at 1300 K and about 10% at 90 K.

  19. Future Circular Collider Study (FCC) kick-off meeting | 12-15 February

    CERN Multimedia

    2014-01-01

    The kick-off meeting of the international "Future Circular Collider Study" (FCC) will take place in Geneva from 12 to 15 February 2014 at the University of Geneva, Unimail site. The programme and registration details can be found on the meeting's website. This meeting is the starting point of the five-year international "Future Circular Collider Study" (FCC). The main emphasis of the conceptual design study will be on a hadron collider with a centre-of-mass energy of the order of 100 TeV in a new tunnel with a 80-100 km circumference for the purposes of studying physics at the highest energies. The study will also include a lepton collider, as a potential intermediate step towards realisation of the hadron facility. Options for e-p scenarios will also be considered. The main purpose of this meeting is to discuss the study topics and to prepare international collaborations. The meeting is a public meeting with a registration deadline closing on Friday 31 Janua...

  20. Effect of Solvothermal Reduction Process on Crystal Phase of Nickel%溶剂热制备条件对镍晶体结构的影响

    Institute of Scientific and Technical Information of China (English)

    米远祝; 刘应亮; 肖勇; 袁定胜; 张静娴

    2005-01-01

    Nickel powders were obtained after chemical reduction of nickel chloride by KBH4 using absolute ethylenediamine as solvent in a stainless autoclave. The product was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD results show that the as-prepared sample have different crystal structures at different reaction temperatures. It was face-centered cubic (fcc) nickel under 200℃, and there was only hexagonal close-packed (hcp) Ni above 300℃. At 250℃, the patterns indicate that both fcc and hcp phases of Ni coexist in the as-prepared sample. When the ethylenediamine was respectively substituted by benzene and toluene, only fcc phase nickel was obtained. SEM and TEM indicate that the fcc Ni is nano-particles with about 100 nm in diameter, and hcp nickel is nano-crystalline clusters.

  1. Orientational Phase Transition Around 274 K in C60 Single Crystal

    Institute of Scientific and Technical Information of China (English)

    徐亚伯; 何丕模; 杨宏顺; 郑萍; 余朝文; 陈兆甲; 张宣嘉; 李文铸

    1994-01-01

    The electrical conductivity of a C60 single crystal around 274 K and the specific heat of C60 crystals from 150 to 340 K have been measured.The delta-like specific heat peak at about 251 K related to the first-order phase transition has been reported.The activation energy change around 274 K and the lambda-like specific heat peak beginning at 270 K and ending at 310 K show that there is an orientational phase transition in fcc C60 crystals above 251 K.By taking the symmetry into consideration and further analyzing lambda-like specific heat peak and the activation energy change around 274 K,the conclusion has been reached that this new phase transition is an orientational structure transition from the merohedral twinning fcc to the orientationally disordered fcc.The temperature of free rotation of C60 molecules is about 281 K.

  2. A REVIEW OF SOME EXISTING DRAG MODELS DESCRIBING THE INTERACTION BETWEEN THE SOLIDGASEOUS PHASES IN A CFB

    Directory of Open Access Journals (Sweden)

    Paladi Lela Naga Ramesh,

    2010-05-01

    Full Text Available This paper examines the suitability of various drag models for predicting the hydrodynamics of the turbulent fluidization of FCC particles on the Fluent V6.2 platform. The drag models reviewed are Syamlal–O’Brien, Gidaspow, Arastoopour and Syamlal–O’Brien, . Comparison between experimental data and simulated results showed that the Syamlal–O’Brien, Arastoopour and Gidaspow models highly overestimated gas–solid momentum exchange and could not predict the formation of dense phase in the fluidized bed. The standard Syamlal–O’Brien drag model was then modified based on the minimum luidization condition. This has proved applicable for FCC particles in turbulent fluidization for the high dense phase, density solid-up phase and low density phases under fast fluidization conditions. This was finally proposed to calculate the gas–solid exchange coefficient in the turbulent fluidization of FCC particles and was validated by satisfactory agreement between prediction and experiment.

  3. Phase-dependent corrosion of titanium-to-stainless steel joints brazed by Ag-Cu eutectic alloy filler and Ag interlayer

    Science.gov (United States)

    Lee, M. K.; Park, J. J.; Lee, J. G.; Rhee, C. K.

    2013-08-01

    The electrochemical corrosion properties of Ti-STS dissimilar joints brazed by a 72Ag-28Cu alloy filler and an Ag interlayer were studied in a 3.5% NaCl solution using potentiodynamic polarization and ac impedance spectroscopy. For a joint with a layered structure of Ti(base)/TiAg/Ag solid solution/Ag-Cu eutectic/STS(base), galvanic corrosion mostly occurred in the TiAg phase with a severe material loss, indicating that the TiAg layer acted as an anode in the galvanic couple in the layered joint. The Ag-rich solid solution layer was also corroded to a certain extent, but the corrosion in this layer was dominated by the selective pitting corrosion of the eutectic Cu-rich phase. With an increase in the brazing temperature, the Cu-rich phases disappeared owing to the enhanced isothermal solidification effect, leading to an improvement of the corrosion resistance.

  4. Simulation for F.C.C. deformation texture by modified pencil glide theory[Face Centered Cubic

    Energy Technology Data Exchange (ETDEWEB)

    Masui, H.

    1999-11-26

    Inspired by the pencil glide theory for b.c.c. metal, modified pencil glide theory for f.c.c. metal was proposed, dividing the 12 glide systems of f.c.c. metal into three groups individually composed of eight {l{underscore}brace}111{r{underscore}brace}{l{underscore}angle}110{r{underscore}angle} glide systems around the principal axes X[100], Y[010] and Z[001]. These assumptions yielded two mathematical solutions {Omega}(3) and {Omega}(1). In {Omega}(3), from the three groups with four complete conjugated glide systems composed of, respectively, two glide systems of common {l{underscore}angle}110{r{underscore}angle} direction, only one group with the maximum plastic work may operate if the requirements are satisfied, otherwise glide systems in {Omega}(1) where one of the four conjugated glide systems is zero are activated. The model considering the 12 glide systems of f.c.c. as a whole explained many experimentally stable orientations in axisymmetric and rolling deformation. The differences between the two pencil glide theories for b.c.c. and f.c.c. are also discussed with data.

  5. Reduction of sulfur in gasoline using catalytic cracking; Reducao de enxofre na gasolina via craqueamento catalitico (FCC)

    Energy Technology Data Exchange (ETDEWEB)

    Roncolatto, Rodolfo E.; Gilbert, William; Chamberlain, Oscar [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas; Keyworth, Don [Akzo Nobel, Arnhem (Netherlands)

    2000-07-01

    FCC catalysts or additives can help in reducing sulfur in cracked naphta. The type of sulfur compounds in the feed has a considerable impact in the sulfur reduction, thiophenic species are less reactive while mercaptans and sulfides are more reactive. Contaminant metals like nickel and vanadium can help in the reduction of sulfur due to their dehydrogenation ability. (author)

  6. The contribution of dislocation - Impurities interaction to kinetics of martensitic transformation of quenched fcc Fe-Ni-Mo alloys

    NARCIS (Netherlands)

    Golovin, [No Value; Goncharov, S; Golovin, SA

    1996-01-01

    The kinetics of martensitic transformation in austenitic Fe-Ni-Mo alloys depends on the carbon content. Analysis of carbon redistribution between f.c.c. solid solution and dislocation has been carried out with the help of internal friction (amplitude and temperature effects) study and stress relaxat

  7. Geometry explains the large difference in the elastic properties of fcc and hcp crystals of hard spheres

    NARCIS (Netherlands)

    Sushko, N; van der Schoot, P

    2005-01-01

    As is well known, hard-sphere crystals of the fcc and hcp type differ very little in their thermodynamic properties. Nonetheless, recent computer simulations by Pronk and Frenkel indicate that the elastic response to mechanical deformation of these two types of crystal are quite different [S. Pronk

  8. Surface segregation of the metal impurity to the (100) surface of fcc metals

    Indian Academy of Sciences (India)

    Jian-Min Zhang; Bo Wang; Ke-Wei Xu

    2007-10-01

    The surface segregation energies for a single metal impurity to the (100) surface of nine fcc metals (Cu, Ag, Au, Ni, Pd, Pt, Rh, Al and Ir) have been calculated using the MAEAM and molecular dynamics (MD) simulation. The results show that the effect of the surface is down to the fourth-layer and an oscillatory or monotonic damping (|1| > |2| > |3| > |4|) phenomenon in segregation energy has been obtained. The absolute value of the segregation energy 1 for a single impurity in the first atomic layer is much higher than that in the nether layers. Thus, whether the surface segregation will work or not is mainly determined by 1 which is in good relation to the differences in surface energy between the impurity and host crystals = imp - hos. So we conclude that an impurity with lower surface energy will segregate to the surface of the host with higher surface energy.

  9. Effect of CO Combustion Promoters on Combustion Air Partition in FCC under Nearly Complete Combustion

    Institute of Scientific and Technical Information of China (English)

    王锐; 罗雄麟; 许锋

    2014-01-01

    With CO combustion promoters, the role of combustion air flow rate for concerns of economics and control is important. The combustion air is conceptually divided to three parts:the air consumed by coke burning, the air consumed by CO combustion and the air unreacted. A mathematical model of a fluid catalytic cracking (FCC) unit, which includes a quantitative correlation of CO heterogeneous combustion and the amount of CO combustion promoters, is introduced to investigate the effects of promoters on the three parts of combustion air. The results show that the air consumed by coke burning is almost linear to combustion air flow rate, while the air consumed by CO combustion promoters tends to saturate as combustion air flow rate increases, indicating that higher air flow rate can only be used as a manipulated variable to control the oxygen content for an economic concern.

  10. Application of Olefin-Reducing Catalyst in FCC Unit at Daqing Petrochemical Company

    Institute of Scientific and Technical Information of China (English)

    Liu Xinfeng; Yang Daoxue; Zhang Guojing; Yao Hua

    2003-01-01

    This article refers to the application of DOCO olefin-reducing catalyst developed by RIPP and manufactured by the Catalyst Factory of Changling Refining and Chemical Company in the 1.4 Mt/a RFCCU at Daqing Petrochemical Company. Results of operation over two months had revealed that this catalyst had good olefin-reducing ability and heavy oil converting ability adapted to paraffinic feedstock. The gasoline olefin yield had been reduced to 36.1 v% from 54.2 v% with gasoline RON rating decreased by 1.4 units. The induction period of gasoline had significantly increased to 952 mm, while the coke yield was increased by 0.05 percentage point with light oil yield dropping by only 0.02 percentage point. The FCC product distribution is favorable.

  11. Reaction Mechanism of Thiophene on Vanadium Oxides under FCC Operating Conditions

    Institute of Scientific and Technical Information of China (English)

    Wang Peng; Zheng Aiguo; Tian Huiping; Long Jun

    2004-01-01

    The reaction mechanism of thiophene on vanadium oxides under FCC operating conditions had been preliminary studied using in-situ FT-IR analysis of thiophene and atmospheric pressure continuous fixed-bed reaction, followed by characterization via pyridine adsorption-temperature programmed desorption method, and FT-IR and XPS spectra. The research had discovered that, under 500C thiophene could undergo the redox reaction with V2O5, while being converted into CO, CO2 as well as SO2 with its conversion rate reaching 41.2%. At the same time the oxidation number of vanadium decreased. The existence of a few Bronsted acid centers on V2O5 could lead to an increase of H2S yield among the products derived from the reaction with thiophene.

  12. A simple model for large-scale simulations of fcc metals with explicit treatment of electrons

    Science.gov (United States)

    Mason, D. R.; Foulkes, W. M. C.; Sutton, A. P.

    2010-01-01

    The continuing advance in computational power is beginning to make accurate electronic structure calculations routine. Yet, where physics emerges through the dynamics of tens of thousands of atoms in metals, simplifications must be made to the electronic Hamiltonian. We present the simplest extension to a single s-band model [A.P. Sutton, T.N. Todorov, M.J. Cawkwell and J. Hoekstra, Phil. Mag. A 81 (2001) p.1833.] of metallic bonding, namely, the addition of a second s-band. We show that this addition yields a reasonable description of the density of states at the Fermi level, the cohesive energy, formation energies of point defects and elastic constants of some face-centred cubic (fcc) metals.

  13. Effect of acid density of HZSM-5 on the oligomerization of ethylene in FCC dry gas

    Institute of Scientific and Technical Information of China (English)

    Xue Ding; Shan Geng; Chunyi Li; Chaohe Yang; Guohui Wang

    2009-01-01

    The oligomerization of ethylene in FCC dry gas over HZSM-5 catalyst with different Si/Al2 ratios was studied. The effect of acid density of catalyst on the oligomerization of ethylene was discussed. By increasing the acid density of catalyst, ethylene conversion showed a linear increase, while the yields of olefins decreased when the acid density of catalyst exceeded 0.14 mmolNH3/g owing to a promotion of hydrogen transfer reaction. Through comparing the average distance between acid sites on catalyst with kinetic diameters of olefins, it was found that the dimerization of ethylene was not restrained by the sparse distribution of acid sites, while the hydrogen transfer reaction of C3 and C4 olefins was limited. On these bases, a conclusion is proposed that the dimerization of ethylene proceeded via Eley-Rideal mechanism, while the hydrogen transfer reaction of C3 and C4 olefins followed the Langmuir-Hinshelwood mechanism.

  14. Laboratory evaluation of FCC commercial catalysts. Analysis of products of industrial importance

    Energy Technology Data Exchange (ETDEWEB)

    Passamonti, Francisco J.; De la Puente, Gabriela; Sedran, Ulises [Instituto de Investigaciones en Catalisis y Petroquimica (INCAPE, FIQ, UNL-CONICET), Santiago del Estero 2654, 3000 Santa Fe (Argentina)

    2008-04-15

    The results of the conversion of a VGO over six equilibrium commercial FCC catalysts with different formulations in a batch CREC Riser Simulator laboratory reactor at 500 and 550 C, catalyst to oil ratio 6.1 and reaction times from 3 to 30 s, were analyzed. It was possible to define the main catalyst characteristics in terms of various evaluation items, such as activity, gasoline yield and quality, LPG yield and coke yield, or the yields of particular compounds like, e.g., isobutane. Important differences in activity between catalysts were not observed, but catalyst properties reflected clearly as significant differences in gasoline, LPG or coke selectivities. Particularly, catalyst's hydrogen transfer properties impacted on gasoline composition and isobutane yield. The results showed that the CREC Riser Simulator reactor is an important tool for the evaluation of both commercial catalysts and feedstocks and process conditions. (author)

  15. Temperature dependence of dynamic deformation in FCC metals, aluminum and invar

    Science.gov (United States)

    Chen, Laura; Swift, D. C.; Austin, R. A.; Florando, J. N.; Hawreliak, J.; Lazicki, A.; Saculla, M. D.; Eakins, D.; Bernier, J. V.; Kumar, M.

    2017-01-01

    Laser-driven shock experiments were performed on fcc metals, aluminum and invar, at a range of initial temperatures from approximately 120-800 K to explore the effect of initial temperature on dynamic strength properties at strain rates reaching up to 107 s-1. In aluminum, velocimetry data demonstrated an increase of peak stress of the elastic wave, σE, with initial temperature. Alternatively, for invar, σE exhibits little-to-no decrease over the same initial temperature range. Aluminum's unusual deformation behavior is found to primarily be due to anharmonic vibrational effects. Differences in the magnetic structure of aluminum and invar can account for discrepancies in high rate deformation behavior.

  16. Assessment and Mitigation of the Proton-Proton Collision Debris Impact on the FCC Triplet

    CERN Document Server

    Besana, Maria Ilaria; Fartoukh, Stephane; Martin, Roman; Tomás, Rogelio

    2016-01-01

    The Future Circular hadron Collider (FCC-hh), which is designed to operate at a centre-of-mass energy of 100 TeV and to deliver ambitious targets in terms of both instantaneous and integrated luminosity, poses extreme challenges in terms of machine protection during operation and with respect to long-term damages. Energy deposition studies are a crucial ingredient for its design. One of the relevant radiation sources are collision debris particles, which de- posit their energy in the interaction region elements and in particular in the superconducting magnet coils of the final focus triplet quadrupoles, to be protected from the risk of quenching and deterioration. In this contribution, the collision debris will be characterised and expectations obtained with FLUKA will be presented, including magnet lifetime considerations. New techniques including crossing angle gymnastics for peak dose deposition mitigation (as recently introduced in the framework of the LHC operation), will be discussed.

  17. Indium-defect interactions in FCC and BCC metals studied using the modified embedded atom method

    Science.gov (United States)

    Zacate, M. O.

    2016-12-01

    With the aim of developing a transferable potential set capable of predicting defect formation, defect association, and diffusion properties in a wide range of intermetallic compounds, the present study was undertaken to test parameterization strategies for determining empirical pair-wise interaction parameters in the modified embedded atom method (MEAM) developed by Baskes and coworkers. This report focuses on indium-solute and indium-vacancy interactions in FCC and BCC metals, for which a large set of experimental data obtained from perturbed angular correlation measurements is available for comparison. Simulation results were found to be in good agreement with experimental values after model parameters had been adjusted to reproduce as best as possible the following two sets of quantities: (1) lattice parameters, formation enthalpies, and bulk moduli of hypothetical equiatomic compounds with the NaCl crystal structure determined using density functional theory and (2) dilute solution enthalpies in metals as predicted by Miedema's semi-empirical model.

  18. Twinning in fcc lattice creates low-coordinated catalytically active sites in porous gold.

    Science.gov (United States)

    Krajčí, Marian; Kameoka, Satoshi; Tsai, An-Pang

    2016-08-28

    We describe a new mechanism for creation of catalytically active sites in porous gold. Samples of porous gold prepared by de-alloying Al2Au exhibit a clear correlation between the catalytic reactivity towards CO oxidation and structural defects in the fcc lattice of Au. We have found that on the stepped {211} surfaces quite common twin boundary defects in the bulk structure of porous gold can form long close-packed rows of atoms with the coordination number CN = 6. DFT calculations confirm that on these low-coordinated Au sites dioxygen chemisorbs and CO oxidation can proceed via the Langmuir-Hinshelwood mechanism with the activation energy of 37 kJ/mol or via the CO-OO intermediate with the energy barrier of 19 kJ/mol. The existence of the twins in porous gold is stabilized by the surface energy.

  19. When magnetic catalyst meets magnetic reactor: etherification of FCC light gasoline as an example.

    Science.gov (United States)

    Cheng, Meng; Xie, Wenhua; Zong, Baoning; Sun, Bo; Qiao, Minghua

    2013-01-01

    The application of elaborately designed magnetic catalysts has long been limited to ease their separation from the products only. In this paper, we for the first time employed a magnetic sulphonated poly(styrene-divinylbenzene) resin catalyst on a magnetically stabilized-bed (MSB) reactor to enhance the etherification of fluidized catalytic cracking (FCC) light gasoline, one of the most important reactions in petroleum refining industry. We demonstrated that the catalytic performance of the magnetic acid resin catalyst on the magnetic reactor is substantially enhanced as compared to its performance on a conventional fixed-bed reactor under otherwise identical operation conditions. The magnetic catalyst has the potential to be loaded and unloaded continuously on the magnetic reactor, which will greatly simplify the current complex industrial etherification processes.

  20. Effect of vacancy defects on generalized stacking fault energy of fcc metals.

    Science.gov (United States)

    Asadi, Ebrahim; Zaeem, Mohsen Asle; Moitra, Amitava; Tschopp, Mark A

    2014-03-19

    Molecular dynamics (MD) and density functional theory (DFT) studies were performed to investigate the influence of vacancy defects on generalized stacking fault (GSF) energy of fcc metals. MEAM and EAM potentials were used for MD simulations, and DFT calculations were performed to test the accuracy of different common parameter sets for MEAM and EAM potentials in predicting GSF with different fractions of vacancy defects. Vacancy defects were placed at the stacking fault plane or at nearby atomic layers. The effect of vacancy defects at the stacking fault plane and the plane directly underneath of it was dominant compared to the effect of vacancies at other adjacent planes. The effects of vacancy fraction, the distance between vacancies, and lateral relaxation of atoms on the GSF curves with vacancy defects were investigated. A very similar variation of normalized SFEs with respect to vacancy fractions were observed for Ni and Cu. MEAM potentials qualitatively captured the effect of vacancies on GSF.

  1. Conversion of pine sawdust bio-oil (raw and thermally processed) over equilibrium FCC catalysts.

    Science.gov (United States)

    Bertero, Melisa; Sedran, Ulises

    2013-05-01

    A raw bio-oil from pine sawdust, the liquid product from its thermal conditioning and a synthetic bio-oil composed by eight model compounds representing the main chemical groups in bio-oils, were converted thermally and over a commercial equilibrium FCC catalyst. The experiments were performed in a fixed bed reactor at 500 °C. The highest hydrocarbon yield (53.5 wt.%) was obtained with the conditioned liquid. The coke yields were significant in all the cases, from 9 to 14 wt.%. The synthetic bio-oil produced lesser hydrocarbons and more oxygenated compounds and coke than the authentic feedstocks from biomass. The previous thermal treatment of the raw bio-oil had the positive effects of increasing 25% the yield of hydrocarbons, decreasing 55% the yield of oxygenated compounds and decreasing 20% the yield of coke, particularly the more condensed coke.

  2. A Selective Octane-Enhancing FCC Catalyst Using ZRP Zeolite as an Active Component

    Institute of Scientific and Technical Information of China (English)

    Huang Dayang; Shu Xingtian; He Mingyuan; Yang Xiaoming; Wang Dianzhong; Zong Baoning

    2001-01-01

    A hetero-crystalline seeding method to prepare a unique MFI type zeolite with mesopores of ca. 4 nm diameter designated as the ZRP zeolite, which possesses high stability and selectivity and is used as component of FCC catalysts to produce high-octane gasoline and light olefins, was developed. With the DOCR and DOCP catalysts containing the ZRP zeolite modified by phosphorus-incorporation as the octaneenhancing catalysts, the commercial trial was carried out in a 0.8Mt/a RFCC unit with a feedstock composed of Daqing atmospheric residue. As compared to the base catalyst, the LPG+gasoline+LCO product yield obtained from this catalyst was increased by 0.53m%. Meanwhile, the RON and MON of gasoline was increased by 1.4 and 2.4 units, respectively. The higher increment of MON is attributable to the higher isoparaffines content in gasoline. This result indicates that the ZRP zeolite possesses higher isomerization selectivity.

  3. Probing Charged Higgs Boson Couplings at the FCC-hh Collider

    CERN Document Server

    Cakir, I T; Saygin, H; Senol, A; Cakir, O

    2015-01-01

    Many of the new physics models predicts a light Higgs boson similar to the Higgs boson of the Standard Model (SM) and also extra scalar bosons. Beyond the search channels for a SM Higgs boson, the future collider experiments will explore additional channels that are specific to extended Higgs sectors. We study the charged Higgs boson production within the framework of two Higgs doublet models (THDM) in the proton-proton collisions at the FCC-hh collider. With an integrated luminosity of 500 fb$^{-1}$ at very high energy frontier, we obtain a significant coverage of the parameter space and distinguish the charged Higgs-top-bottom interaction within the THDM or other new physics models with charged Higgs boson mass up to 1 TeV.

  4. 催化裂化油浆溶剂抽提及其中间相沥青%EXTRACTION OF FCC SLURRY WITH SOLVENT AND THE MESOPHASE PITCH DERIVED FROM EXTRACT

    Institute of Scientific and Technical Information of China (English)

    查庆芳; 张玉贞; 巩春伟; 刘国祥; 吴明铂

    2001-01-01

    The properties of the catalytic cracking slurry(FCC slurry)extracted with furfurol at different temperatures and in solvent-slurry ratio were determined.The optimum conditions for solvent extraction are 50 ℃ and 2∶1 solvent-slurry ratio.The selectivity calculated shows that furfurol is an excellent extraction solvent for separating FCC slurry.The mesophase pitch derived from the extract with high content of soluble mesophase constituents will improve the molecular orientation and exhibit optically coarse fibrous texture with better fluidity during liquid phase carbonization that is good for making graphitizing carbon.The mesophase pitch obtained from the extraciton residue oil with coarse mosaic texture and lower soluble mesophase constituents is not a good precursor for excellent carbon material,but it is a good feedstock for FCC instead.%考察了FCC油浆及其在不同温度、不同剂油比条件下抽出油的组成和性质。确定了最佳抽提条件为50 ℃,剂油比为2∶1。计算所得选择性表明糠醛是分离FCC油浆的有效溶剂。抽出油形成的中间相沥青,具有良好的可溶性,显现广域流线型大融并体,分子排列规整,具有较佳的流动性,是一种易石墨化炭。抽余油形成的中间相沥青,显示粗镶嵌结构,可溶性较差,难以制取上佳炭材料,但可回收作催化裂化原料。

  5. From Kepler's conjecture and fcc lattice to modelling of crowding in living matter.

    Science.gov (United States)

    Del Monte, Ugo; Caiani, Enrico G

    2013-01-01

    Up to now, sphere packing has been investigated without any reference to living matter. This study focuses on the void space (VS) of sphere packing to mimic the extracellular spaces of living tissues. It was inspired by the importance of the extracellular matrix, the vehicle of micro and macromolecules involved in cell metabolism, intercellular communication and drug delivery. The analysis of sphere packing evidenced that in uniform random packing VS is about 1.9 times greater than in the face centered cubic (fcc) lattice (thus being very close to the 1.9 volume ratio of the cube to the sphere). This datum is a good reference for cell packing in vivo. The disproportionate increase of VS per sphere in loose packing in vitro is analyzed having in mind the variability in volume and composition of the interstitial spaces in vivo and cell trafficking. Arrangements of lymphocytes mimicking a two-dimensional hexagonal pattern and dense packing of disks generated by numerical procedures, are described in 7 micro m-thick haematoxylin and eosin-stained histological slices from a human lymph node. In narrow tubes simulating roundish cells arranged in limited compartments of the interstice, sphere packing is characterized by noticeable increases of VS. The VS of this packing in vitro is compatible with variability in volume and composition of the interstitial spaces and with cell trafficking in vivo. This paper stresses that in mammalian tissues and organs cells can be packed quite more densely than spheres in the fcc lattice. As to pathology, attention is focused: (i) on overcrowding of cell organelles in some diseases, (ii) on shrinking or swelling of high amplitude, whose opposite effects are to concentrate or dilute intracellular structures and crowding of macromolecules, and (iii) on neoplastic tissues.

  6. Mechanism of unique hardening of dental Ag-Pd-Au-Cu alloys in relation with constitutional phases

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yonghwan [Department of Materials Science, Graduate School of Engineering, Tohoku University, 6-6 Aoba, Aramaki Aza, Aoba-ku, Sendai 980-8579 (Japan); Niinomi, Mitsuo, E-mail: niinomi@imr.tohoku.ac.jp [Department of Biomaterials Science, Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Nakai, Masaaki; Akahori, Toshikazu [Department of Biomaterials Science, Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Kanno, Toru [Department of Materials Science, Graduate School of Engineering, Tohoku University, 6-6 Aoba, Aramaki Aza, Aoba-ku, Sendai 980-8579 (Japan); Fukui, Hisao [Department of Dental Materials Science, School of Dentistry, Aichi-Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya 464-8650 (Japan)

    2012-04-05

    Highlights: Black-Right-Pointing-Pointer The unique hardening behavior on Ag-Pd-Au-Cu alloys by solution treatment was investigated. Black-Right-Pointing-Pointer The Cu-rich {alpha}{sub 1} phase and Ag-rich {alpha}{sub 2} phase decomposed by solution treatment contributed weakly to the change of hardness. Black-Right-Pointing-Pointer The fine {beta} phases precipitated by aging treatment caused great increase in hardness. Black-Right-Pointing-Pointer The fine L1{sub 0}-type ordered {beta} Prime phase precipitated by solution treatment may contribute to the unique hardening behavior. - Abstract: The objective of this research was to investigate the effect of constitutional phases on the unique hardening behavior of as-solutionized dental Ag-Pd-Au-Cu alloy fabricated by cold rolling. The commercial dental Ag-Pd-Au-Cu alloy fabricated by cold rolling consists of Cu-rich {alpha}{sub 1}, Ag-rich {alpha}{sub 2}, and {beta} phases. On the other hand, the Ag-Pd-Au-Cu alloy fabricated by the liquid rapid solidification (LRS) method consists of single {alpha} phase. They were subjected to various heat treatments, respectively. The microstructures were observed by scanning electron microscope, transmission electron microscope and X-ray diffraction. The hardness was evaluated by a Vickers micro-hardness tester. In the Ag-Pd-Au-Cu alloy fabricated by cold rolling, the fine L1{sub 0}-type-ordered {beta} Prime phase is precipitated and the coarse {beta} phase is remained after solution treatment at 1123 K. The hardness increases drastically. On the other hand, in the Ag-Pd-Au-Cu alloy fabricated by LRS method, the single {alpha} phase was decomposed into the {alpha}{sub 1} phase and the {alpha}{sub 2} phase after solution treatment at 1023 K and its hardness change was small. However, after aging treatment at 673 K, the fine {beta} phase is precipitated in the {alpha} phase and the hardness increases greatly even in the Ag-Pd-Au-Cu alloy fabricated by LRS method. It is considered

  7. Study of the physics potential of the FCC-hh machine to measure the coupling of the Higgs boson to b quarks

    CERN Document Server

    Rodríguez, Arturo

    2016-01-01

    The FCC project as well as the Pythia + Delphes analysis within the FCC software are introduced. The ROOT analysis carried out to reconstruct main observables, such the invariant mass of the bb system, transverse mass and momentum of the W boson together with the lepton pT and distribution is explained. The resulting reconstructed invariant mass of the bb system showed a peak near the 125 GeV in correspondence with the Higgs boson. Future steps towards estimating the physics potential of the FCC-hh machine in this channel are discussed.

  8. The phase diagram and the magnetic structure of nuclear spins in elemental copper below 60 nK

    DEFF Research Database (Denmark)

    Siemensmeyer, K.; Steiner, M.; Weinfurther, H.;

    1992-01-01

    The phase diagram for nuclear magnetic order is elemental copper and the corresponding ordering vectors were investigated by neutron diffraction at nanokelvin temperatures. The intermediate phase is characterized by an ordering vector (O 2/3 2/3). This is the first time that this type of order is...... is observed in an fcc antiferromagnet....

  9. Effect of alloying element nickel on structural stability of FCC Fe-Cu precipitates studied by first-principles calculations%合金元素镍对FCC Fe-Cu析出相结构稳定性的影响

    Institute of Scientific and Technical Information of China (English)

    温玉锋; 孙坚

    2013-01-01

    采用基于投影缀加波赝势和广义梯度近似的第一性原理和特殊准随机结构模型计算FCC结构Fe-25Cu、Fe-31.25Cu、Fe-3.125Ni-25Cu和Fe-3.125Ni-31.25Cu无序固溶体的基态性质、弹性常数以及电子结构,其中无序固溶体晶胞结构建立在由特殊准随机结构方法所产生的结构模型基础上。计算结果表明:FCC 结构Fe-Ni-Cu无序固溶体存在无磁性与铁磁性两种状态,其中铁磁性 Fe-Cu 和 Fe-Ni-Cu 无序固溶体的能量相对较低;铁磁性Fe-25Cu和Fe-3.125Ni-25Cu无序固溶体不满足Born弹性稳定性准则,而Fe-31.25Cu和Fe-3.125Ni-31.25Cu无序固溶体满足Born弹性稳定性准则,以亚稳态形式存在,合金元素Ni的加入显著提高了铁磁性FCC结构Fe-31.25Cu无序固溶体的结构稳定性。%The first-principles method based on projector augmented wave pseudo-potential and generalized gradient approximation was employed to calculate the ground state properties, elastic constants and electronic structures of FCC structured Fe-25Cu, Fe-31.25Cu, Fe-3.125Ni-25Cu and Fe-3.125Ni-31.25Cu random solid solutions. The cells of the random solid solutions were established based on the special quasirandom structure (SQS) models. The calculated results show that nonmagnetic and ferromagnetic states exist in FCC Fe-Ni-Cu random solid solutions, and Fe-Cu and Fe-Ni-Cu random solid solutions in the ferromagnetic state have lower energy. The ferromagnetic Fe-25Cu and Fe-3.125Ni-25Cu random solid solutions do not satisfy Born criterion of elastic stability, whereas the Fe-31.25Cu and Fe-3.125Ni-31.25Cu random solid solutions satisfy Born criterion of elastic stability and can exist as a metastable phase. The addition of alloying element of nickel can significantly improve the structural stability of FCC Fe-31.25Cu random solid solution.

  10. 典型晶格结构FCC/BCC钢的剧烈塑性变形研究现状%Research progress on severe plastic deformation of steels with BCC/FCC crystal structures

    Institute of Scientific and Technical Information of China (English)

    马明; 蔡明晖; 唐正友; 丁桦

    2015-01-01

    晶格结构(体心立方BCC、面心立方FCC及其复合形式)类型对金属材料剧烈塑性变形过程中的晶粒细化机制产生重要影响。本文以不同晶格结构的钢铁材料为对象,重点阐述和总结了不同晶格结构类型及其变形模式差异对剧烈塑性变形过程中晶粒细化理论、组织形貌和力学性能的影响规律,其结果有望为探索剧烈塑性变形工艺过程中的组织细化理论提供一个新途径。%The crystal-structure types of metallic materials such as face-centered cubic ( FCC) and body-centered cubic ( BCC) play a crucial role on ultra-grain refinement during severe plastic deformation ( SPD) . This work will focus on three different types of steels with BCC, FCC, and BCC/FCC crystal structures, and comprehensively discuss and summarize the influence of different crystal - structure types on deformation modes, ultra - grain refinement, microstructure and properties, which will provide a new route to apply and develop this theory to ultra - grain refinement of metallic materials through SPD processing.

  11. Simulating Proton Synchrotron Radiation in the Arcs of the LHC, HL-LHC, and FCC-hh

    CERN Document Server

    Guillermo Cantón, Gerardo; Zimmermann, Frank

    2016-01-01

    At high proton-beam energies, beam-induced synchrotron radiation is an important source of heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can give rise to an electron cloud. We use the Synrad3D code developed at Cornell to simulate the photon distributions in the arcs of the LHC, HL-LHC, and FCC-hh. Specifically, for the LHC we study the effect of the “sawtooth” chamber, for the HL-LHC the consequences of the ATS optics with large beta beating in the arcs, and for the FCC-hh the effect of a novel beam-screen design, with a long slit surrounded by a “folded” antechamber.

  12. Correlation effects in fcc-Fe(x)Ni(1-x) alloys investigated by means of the KKR-CPA.

    Science.gov (United States)

    Minár, J; Mankovsky, S; Šipr, O; Benea, D; Ebert, H

    2014-07-09

    The electronic structure and magnetic properties of the disordered alloy system fcc-FexNi1-x (fcc: face centered cubic) have been investigated by means of the KKR-CPA (Korringa-Kohn-Rostoker coherent potential approximation) band structure method. To investigate the impact of correlation effects, the calculations have been performed on the basis of the LSDA (local spin density approximation), the LSDA + U as well as the LSDA + DMFT (dynamical mean field theory). It turned out that the inclusion of correlation effects hardly changed the spin magnetic moments and the related hyperfine fields. The spin-orbit induced orbital magnetic moments and hyperfine fields, on the other hand, show a pronounced and element-specific enhancement. These findings are in full accordance with the results of a recent experimental study.

  13. Prospects for $\\gamma \\gamma \\to H$ and $\\gamma \\gamma \\to W^{+}W^{-}$ measurements at the FCC-ee

    CERN Document Server

    Teles, Patricia Rebello

    2015-01-01

    We study the possibilities for the measurement of two-photon production of the Higgs boson (in the $b \\bar{b}$ decay channel), and of $W^{+}W^{-}$ pairs (decaying into four jets) in $e^{+}e^{-}$ collisions at the the Future Circular Collider (FCC-ee). The processes are simulated with the PYTHIA and MADGRAPH 5 Monte Carlo codes, using the effective photon approximation for the $e^{+}e^{-}$ photon fluxes, at center-of-mass energies $\\sqrt{s} = $ 160 GeV and 240 GeV. The analyses include electron-positron tagging, realistic acceptance and reconstruction efficiencies for the final-state jets, and selection criteria to remove the backgrounds. Observation of both channels is achievable with the expected few ab$^{-1}$ integrated luminosities at FCC-ee.

  14. NCTA v. FCC - Do Commercial Free Speech Justifications Trump Consumers' Personal Data Protection Rights? Answer To Shape Mobile Advertising Industry

    DEFF Research Database (Denmark)

    Cleff, Evelyne Beatrix; King, Nancy J.

    2010-01-01

    requiring carriers to obtain customers' advance approval before releasing their telephone record information for marketing purposes. NCTA claimed the FCC's new opt-in rule violates companies' First Amendment right to engage in commercial speech. At stake in this appeal was the constitutionally required...... balance between protecting consumers' information privacy in an era of pervasive data processing and protecting the rights of marketers to engage in protected commercial free speech that involves using customers' personal information. A ruling against the FCC would have limited the use of government......'s right to communicate with their customers. Considering privacy risks associated with advances in computer technology, the complexities of modern information processing and evolving mobile advertising (m-advertising) practices, privacy regulations should not be equated with unwarranted speech regulations...

  15. Influence of carbon, nitrogen and oxygen impurities on the ductility and electronic properties of fcc iridium: First-principles study

    Science.gov (United States)

    Bannikov, V. V.; Shein, I. R.; Ivanovskii, A. L.

    2009-11-01

    Unusual changes in mechanical and electronic properties of fcc Ir in the presence of light sp elements (carbon, nitrogen and oxygen) as interstitial impurities have been predicted. By means of the ab initio calculations we found that, in contrast to the majority of other d metals, the ductility of iridium increases in the presence of the above impurities simultaneously with its "metallization" — owing to appreciable growth of the near-Fermi density of states.

  16. ESTUDIO COMPARATIVO DE PASTAS DE CEMENTO ADICIONADAS CON CATALIZADOR DE CRAQUEO CATALÍTICO USADO (FCC, Y METACAOLIN (MK

    Directory of Open Access Journals (Sweden)

    Janneth Torres Agredo

    2012-01-01

    Full Text Available Este artículo es parte de un proyecto de investigación cuyo objetivo principal es evaluar el desempeño de un residuo de una refinería de petróleo, como adición al cemento Portland con el fin de establecer la viabilidad de su aplicación en materiales de construcción. Este residuo denominado catalizador usado a partir del proceso de craqueo catalítico (fcc procede de las unidades de ruptura catalítica en lecho fluido y está compuesto principalmente por sílice y alúmina. Se analizó la hidratación en pastas de cemento adicionadas con el fcc, y se hizo una comparación con la adición de metacaolín (mk. Para realizar el estudio, se prepararon pastas de cemento Portland Ordinario (opc, adicionadas en porcentajes del 10 y 20% de fcc y mk como reemplazo de cemento. La actividad puzolánica de las adiciones y el tipo de productos de hidratación se determinaron mediante las técnicas de difracción de rayos X (drx y del análisis termogravimétrico (tg/dtg. Como fases principales del proceso de hidratación en las pastas adicionadas con fcc se encontraron silicatos cálcicos hidratados (csh, aluminatos cálcicos hidratados (cah, y silico aluminatos cálcicos (cash, productos similares a los obtenidos en pastas adicionadas con metacaolín.

  17. Graphene oxide-templated synthesis of ultrathin or tadpole-shaped au nanowires with alternating hcp and fcc domains.

    Science.gov (United States)

    Huang, Xiao; Li, Shaozhou; Wu, Shixin; Huang, Yizhong; Boey, Freddy; Gan, Chee Lip; Zhang, Hua

    2012-02-14

    Ultrathin Au nanowires (AuNWs) and tadpole-shaped nanowires are synthesized on graphene oxide (GO) sheet templates. For the first time, 1.6 nm-diameter AuNWs are shown to contain hexagonal close-packed (hcp) crystal domains, and the tadpole-shaped nanowires exhibit alternating sets of hcp and face-centered cubic (fcc) structures, associated with variation in wire thickness.

  18. Quench Protection Study of the Eurocircol 16 T cosθ Dipole for the Future Circular Collider (FCC)

    CERN Document Server

    Marinozzi, Vittorio; Caiffi, Barbara; Fabbricatore, Pasquale; Farinon, Stefania; Salmi, Tiina-Mari; Sorbi, Massimo Leone; Stenvall, Antti; Volpini, Giovanni

    2016-01-01

    After LHC will be turned off, a new, more energetic machine will be needed in order to explore unknown regions of the high-energy physics. For this reason, the project Future Circular Collider (FCC) has started, with the goal of developing a 100 km circumference collider of 50 TeV proton beams. The Eurocircol collaboration is part of the FCC study under the European Community leadership, and it aims to develop a conceptual design of FCC within 2019. One of the main targets is to design a bending dipole able to reach 16 T operation magnetic field, in order to accomplish the size and energy constraints. Such a magnetic field can be reached using Nb3Sn conductors at their highest performance. One option under exploration is the Cosθ dipole, by INFN of Milano and Genova. One of the aspects to be taken into consideration is the amount of conductor needed, because of the relatively high cost of superconducting cables involving Nb3Sn. The amount of superconductor in the cross-section conductor area is a discriminan...

  19. Self-energy and interaction energy of stacking fault in fcc metals calculated by embedded-atom method

    Institute of Scientific and Technical Information of China (English)

    何刚; 戎咏华; 徐祖耀

    2000-01-01

    The stacking fault energies of five fcc metals (Cu, Ag, Au, Ni and Al) with various quan-tivalences have been calculated by embedded-atom method (EAM). It indicated that the stacking fault energy is mainly determined by the metallic bond-energy and the lattice constant. Thus, monovalent fcc metals should have different stacking fault energies, contrary to Attree’s conclusion. The interaction energy between stacking faults one I 111 I layer apart in a fcc metal is found to be 1/40-1/250 of its self-energy, while it becomes zero when the two stacking faults are two layers apart. The twin energy is just half of the energy of intrinsic stacking fault energy without the consideration of lattice relaxation and the energy of a single intrinsic stacking fault is almost the same as that of extrinsic stacking fault, which are consistent with the results from the calculation of Lennard-Jones force between atoms, but differ from Attree’s result.

  20. Effects of dopants on the amorphous-to-fcc transition in Ge{sub 2}Sb{sub 2}Te{sub 5} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Privitera, S. [R and D Department, Micro, Power, Analog (MPA) Group, STMicroelectronics, MP8, Stradale Primosole 50, 95121 Catania (Italy)]. E-mail: stefania.privitera@st.com; Rimini, E. [Istituto di Microelettronica e Microsistemi (IMM), Consiglio Nazionale delle Ricerche (CNR), Stradale Primosole 50, 95121 Catania (Italy); Bongiorno, C. [Istituto di Microelettronica e Microsistemi (IMM), Consiglio Nazionale delle Ricerche (CNR), Stradale Primosole 50, 95121 Catania (Italy); Pirovano, A. [FTM, Advanced R and D, NVMTD, STMicroelectronics, Via Olivetti 2, 20041, Agrate Brianza (Italy); Bez, R. [FTM, Advanced R and D, NVMTD, STMicroelectronics, Via Olivetti 2, 20041, Agrate Brianza (Italy)

    2007-04-15

    The amorphous-to-crystal transition has been studied through in situ resistance measurements in Ge{sub 2}Sb{sub 2}Te{sub 5} thin films doped by ion implantation with nitrogen, oxygen or fluorine at different concentrations. Enhancement of the thermal stability has been observed in O and N amorphous doped Ge{sub 2}Sb{sub 2}Te{sub 5}. Larger effects have been found in the case of nitrogen doping. On the contrary, doping with Fluorine produced a decrease in the crystallization temperature. The electrical properties have been related to the structural phase change through in situ transmission electron microscopy analysis. The comparison between undoped and doped Ge{sub 2}Sb{sub 2}Te{sub 5} shows that the introduction of oxygen or nitrogen modifies in a different way the kinetics of the amorphous-to-fcc transition and gives new insight on the effects of doping with light elements in GeSbTe alloys.

  1. Prediction of gasoline yield in a fluid catalytic cracking (FCC riser using k-epsilon turbulence and 4-lump kinetic models: A computational fluid dynamics (CFD approach

    Directory of Open Access Journals (Sweden)

    Muhammad Ahsan

    2015-07-01

    Full Text Available Fluid catalytic cracking (FCC is an essential process for the conversion of gas oil to gasoline. This study is an effort to model the phenomenon numerically using commercial computational fluid dynamics (CFD software, heavy density catalyst and 4-lump kinetic model. Geometry, boundary conditions and dimensions of industrial riser for catalytic cracking unit are conferred for 2D simulation using commercial CFD code FLUENT 6.3. Continuity, momentum, energy and species transport equations, applicable to two phase solid and gas flow, are used to simulate the physical phenomenon as efficient as possible. This study implements and predicts the use of the granular Eulerian multiphase model with species transport. Time accurate transient problem is solved with the prediction of mass fraction profiles of gas oil, gasoline, light gas and coke. The output curves demonstrate the breaking of heavy hydrocarbon in the presence of catalyst. An approach proposed in this study shows good agreement with the experimental and numerical data available in the literature.

  2. Paramagnetic atom number and paramagnetic critical pressure of the sc, bcc and fcc Ising nanolattices

    Science.gov (United States)

    Şarlı, Numan

    2015-01-01

    The effects of the magnetic atom number in the unit volume on the magnetic properties are investigated by using sc (n=8), bcc (n=9) and fcc (n=14) Ising NLs within the effective field theory with correlations. We find that the magnetic properties expand as the magnetic atom number increases in the unit volume and this expanding constitutes an elliptical path at TC. The effect of the magnetic atom number (n) in the unit volume on the magnetic properties (mp) appear as nscconstant is directly proportional with the atom number in the unit volume (C α n). Hence, by using the slopes of the paramagnetic hysteresis curves of any nanosystem, it can be predicted that the number of particles in its unit volume. Moreover, the magnetic atoms in the paramagnetic region can be considered as particles in the gas. Because of the absence of an external magnetic field, the spin orientations of these atoms are random and free to rotate. Hence, they act on individually with no mutual interaction between two nearest-neighbor magnetic atoms. Therefore, we use the statistical mechanics form of the ideal gas law in the paramagnetic region and we obtain the critical paramagnetic pressure (PC=npkBTC) of the Ising NLs at TC. We define the paramagnetic magnetic atom number in the unit volume as np=n(1-M(T)).

  3. The complex nature of the nuclear star cluster in FCC 277

    CERN Document Server

    Lyubenova, Mariya; Cote, Patrick; Kuntschner, Harald; van de Ven, Glenn; Ferrarese, Laura; Jordan, Andres; Infante, Leopoldo

    2013-01-01

    Recent observations have shown that compact nuclear star clusters (NSCs) are present in up to 80% of galaxies. However, detailed studies of their dynamical and chemical properties are confined mainly to spiral galaxy hosts, where they are more easily observed. In this paper we present our study of the NSC in FCC 277, a nucleated elliptical galaxy in the Fornax cluster. We use a combination of adaptive optics assisted near-infrared integral field spectroscopy, Hubble Space Telescope imaging, and literature long slit data. We show that while the NSC does not appear to rotate within our detection limit of ~6 km/s, rotation is detected at larger radii, where the isophotes appear to be disky, suggesting the presence of a nuclear disk. We also observe a distinct central velocity dispersion drop that is indicative of a dynamically cold rotating sub-system. Following the results of orbit-based dynamical modelling, co-rotating as well as counter-rotating stellar orbits are simultaneously needed to reproduce the observ...

  4. Quasi-static crack tip fields in rate-sensitive FCC single crystals

    Indian Academy of Sciences (India)

    P Biswas; R Narasimhan

    2012-02-01

    In this work, the effects of loading rate, material rate sensitivity and constraint level on quasi-static crack tip fields in a FCC single crystal are studied. Finite element simulations are performed within a mode I, plane strain modified boundary layer framework by prescribing the two term $(K −T)$ elastic crack tip field as remote boundary conditions. The material is assumed to obey a rate-dependent crystal plasticity theory. The orientation of the single crystal is chosen so that the crack surface coincides with the crystallographic (010) plane and the crack front lies along $[10\\bar{1}]$ direction. Solutions corresponding to different stress intensity rates $\\dot{K}$, -stress values and strain rate exponents are obtained. The results show that the stress levels ahead of the crack tip increase with $\\dot{K}$ which is accompanied by gradual shrinking of the plastic zone size. However, the nature of the shear band patterns around the crack tip is not affected by the loading rate. Further, it is found that while positive -stress enhances the opening and hydrostatic stress levels ahead of crack tip, they are considerably reduced with imposition of negative -stress. Also, negative -stress promotes formation of shear bands in the forward sector ahead of the crack tip and suppresses them behind the tip.

  5. Laboratory evaluation of the impact of the addition of resid in FCC

    Energy Technology Data Exchange (ETDEWEB)

    Devard, Alejandra; de la Puente, Gabriela; Sedran, Ulises [Instituto de Investigaciones en Catalisis y Petroquimica (INCAPE, FIQ, UNL-CONICET), Santiago del Estero 2654 (3000) Santa Fe (Argentina)

    2009-01-15

    The conversion and product distributions from a mixture of 10% atmospheric tower bottom resid and a DO hydrocarbon cut similar to LCO that represented commercial feedstocks were assessed over two equilibrium commercial FCC catalysts in a laboratory CREC Riser Simulator reactor. The reaction temperature was 550 C, the catalyst to oil ratio was 5.8 and the reaction times were up to 25 s. The conversion of the mixture as compared to the DO base feed was higher in the case of the most active, conventional catalyst, and remained very similar on the resid catalyst. Since the yields of the main hydrocarbon groups dry gas, LPG, gasoline and coke followed very similar trends when the two pure feedstocks were converted, the corresponding yields from the mixture also obeyed that behaviour, and were the consequence of the conversion reached. The impact of the different catalyst formulations was observed in, for example, the selectively different yields obtained from the conversion of the resid, and in the composition of the gasoline. Independently of the catalyst, the gasoline was more olefinic and less aromatic when the resid was present. It was shown that in order to evaluate properly a given combination of feeds, catalysts and conditions, they must be considered together. (author)

  6. The theoretical tensile strength of fcc crystals predicted from shear strength calculations

    Science.gov (United States)

    Černý, M.; Pokluda, J.

    2009-04-01

    This work presents a simple way of estimating uniaxial tensile strength on the basis of theoretical shear strength calculations, taking into account its dependence on a superimposed normal stress. The presented procedure enables us to avoid complicated and time-consuming analyses of elastic stability of crystals under tensile loading. The atomistic simulations of coupled shear and tensile deformations in cubic crystals are performed using first principles computational code based on pseudo-potentials and the plane wave basis set. Six fcc crystals are subjected to shear deformations in convenient slip systems and a special relaxation procedure controls the stress tensor. The obtained dependence of the ideal shear strength on the normal tensile stress seems to be almost linearly decreasing for all investigated crystals. Taking these results into account, the uniaxial tensile strength values in three crystallographic directions were evaluated by assuming a collapse of the weakest shear system. Calculated strengths for \\langle 001\\rangle and \\langle 111\\rangle loading were found to be mostly lower than previously calculated stresses related to tensile instability but rather close to those obtained by means of the shear instability analysis. On the other hand, the strengths for \\langle 110\\rangle loading almost match the stresses related to tensile instability.

  7. Rethinking the Kang Custer v. FCC%康卡斯特诉FCC案再思考

    Institute of Scientific and Technical Information of China (English)

    赵康

    2013-01-01

    本文对康卡斯特诉FCC案进行了梳理,分析了上诉法院的判决依据。从传媒经营的角度来看,传媒企业具有两重性:政治属性和经济属性。这要求对于与传媒有关的判例,既要照顾到传媒企业的盈利动机,又不能妨碍传媒肩负表达自由的社会功能。网络中立原则并不能兼顾两个属性,所以不适合做强制性立法。%This paper summarizes Con Kast v. FCC, analyzes the appeal court decision basis. From the point of view of media management, media companies with duality:political and economic attribute. The requirements for the media and the relevant case, not only to take care of the profit motive of media enterprise, and not hinder the media shoulder the expression of social function of the freedom. The principle of network neutrality does not take into account the two attributes, so it is not suitable for mandatory legislation.

  8. Single beam collective effects in FCC-ee due to beam coupling impedance

    CERN Document Server

    Belli, Eleonora; Persichelli, Serena; Zobov, Mikhail

    2016-01-01

    The Future Circular Collider study, hosted by CERN to design post-LHC particle accelerator options in a worldwide context, is focused on proton-proton high-energy and electron-positron high-luminosity frontier machines. This new accelerator complex represents a great challenge under several aspects, which involve R&D on beam dynamics and new technologies. One very critical point in this context is represented by collective effects, generated by the interaction of the beam with self-induced electromagnetic fields, called wake fields, which could produce beam instabilities, thus reducing the machines performance and limiting the maximum stored current. It is therefore very important to be able to predict these effects and to study in detail potential solutions to counteract them. In this paper the resistive wall and some other important geometrical sources of impedance for the FCC electron-positron accelera- tor are identified and evaluated, and their impact on the beam dynamics, which in some cases could l...

  9. Crystal-momentum dispersion of ultrafast spin change in fcc Co.

    Science.gov (United States)

    Si, M S; Li, J Y; Yang, D Z; Xue, D S; Zhang, G P

    2014-05-23

    Nearly twenty years ago, Beaurepaire and coworkers showed that when an ultrafast laser impinges on a ferromagnet, its spin moment undergoes a dramatic change, but how it works remains a mystery. While the current experiment is still unable to resolve the minute details of the spin change, crystal momentum-resolved techniques have long been used to analyze the charge dynamics in superconductors and strongly correlated materials. Here we extend it to probe spin moment change in the entire three-dimensional Brillouin zone for fcc Co. Our results indeed show a strong spin activity along the Δ line, supporting a prior experimental finding. The spin active pockets coalesce into a series of spin surfaces that follow the Fermi surfaces. We predict two largest spin change pockets which have been elusive to experiments: one pocket is slightly below the Δ line and the other is along the Λ line and close to the L point. Our theory presents an opportunity for the time-, spin- and momentum-resolve photoemission technique.

  10. Pressure induced manifold enhancement of Li-kinetics in FCC fullerene.

    Science.gov (United States)

    Das, Deya; Han, Sang Soo; Lee, Kwang-Ryeol; Singh, Abhishek K

    2014-10-21

    The reduction of the diffusion energy barrier for Li in electrodes is one of the required criteria to achieve better performances in Li ion batteries. Using density functional theory based calculations, we report a pressure induced manifold enhancement of Li-kinetics in bulk FCC fullerene. Scanning of the potential energy surface reveals a diffusion path with a low energy barrier of 0.62 eV, which reduces further under the application of hydrostatic pressure. The pressure induced reduction in the diffusion barrier continues till a uniform volume strain of 17.7% is reached. Further enhancement of strain increases the barrier due to the repulsion caused by C-C bond formation between two neighbouring fullerenes. The decrease in the barrier is attributed to the combined effect of charge transfer triggered by the enhanced interaction of Li with the fullerene as well as the change in profile of the local potential, which becomes more attractive for Li. The lowering of the barrier leads to an enhancement of two orders of magnitude in Li diffusivity at room temperature making pressurized bulk fullerene a promising artificial solid electrolyte interface (SEI) for a faster rechargeable battery.

  11. Single-crystal adsorption calorimetry and density functional theory of CO chemisorption on fcc Co{110}.

    Science.gov (United States)

    Liao, Kristine; Fiorin, Vittorio; Gunn, David S D; Jenkins, Stephen J; King, David A

    2013-03-21

    Using single-crystal adsorption calorimetry (SCAC) and density functional theory (DFT), the interaction of carbon monoxide on fcc Co{110} is reported for the first time. The results indicate that adsorption is consistent with molecular chemisorption at all coverages. The initial heat of adsorption of 140 kJ mol(-1) is found in the range of heat values calorimetrically measured on other ferromagnetic metal surfaces, such as nickel and iron. DFT adsorption energies are in good agreement with the experimental results, and comparison between SCAC and DFT for CO on other ferromagnetic surfaces is made. The calculated dissociation barrier of 2.03 eV implies that dissociation at 300 K is unlikely even at the lowest coverage. At high coverages during the adsorption-desorption steady state regime, a pre-exponential factor for CO desorption of 1.2 × 10(17) s(-1) is found, implying a localised molecular adsorbed state prior to desorption in contrast to what we found with Ni surfaces. This result highlights the importance of the choice of the pre-exponential factor in evaluating the activation energy for desorption.

  12. Orientation dependence of the plastic slip near notches in ductile FCC single crystals

    Science.gov (United States)

    Crone, W. C.; Shield, T. W.; Creuziger, A.; Henneman, B.

    2004-01-01

    Results from experiments conducted on copper FCC single crystals are reported. Two symmetric crystallographic orientations and four nonsymmetric crystallographic orientations were tested. The slip line fields that form near a pre-existing notch in these specimens were observed. The changes in these patterns as the orientation of the notch in the crystal is rotated in an {101} plane are discussed. Sectors of similar slip line patterns are identified and the type of boundaries between these sectors are discussed. A type of sector boundary called mixed kink is identified. Specimen orientations that differ by 90° are found to have different slip line patterns, contrary to the predictions of perfectly plastic slip line theory. The locations of the first slip lines to form are compared to the predictions obtained using anisotropic linear elastic stress field solutions and the initial plane-strain yield surfaces. It is found that comparison of these surface slip line fields to plane strain crack tip solutions in the annular region between 350 and 750 μm is justified. The differences in anisotropic elastic solutions for orientations that are 90° apart explain the lack of agreement with perfectly plastic slip line theory.

  13. Workshop on High-precision $\\alpha_s$ measurements from LHC to FCC-ee

    CERN Document Server

    S. Alekhin; d'Enterria, David; A. Banfi; S. Bethke; J. Blümlein; K.G. Chetyrkin; D. d’Enterria; G. Dissertori; X. Garcia i Tormo; A. H. Hoang; M. Klasen; T. Klijnsma; S. Kluth; J.-L. Kneur; B.A. Kniehl; D. W. Kolodrubetz; J. Kühn; P. Mackenzie; B. Malaescu; V. Mateu; L. Mihaila; S. Moch; K. Mönig; R. Pérez-Ramos; A. Pich; J. Pires; K. Rabbertz; G. P. Salam; F. Sannino; J. Soto i Riera; M. Srebre; I. W. Stewart

    2015-01-01

    This document provides a writeup of all contributions to the workshop on "High precision measurements of $\\alpha_s$: From LHC to FCC-ee" held at CERN, Oct. 12--13, 2015. The workshop explored in depth the latest developments on the determination of the QCD coupling $\\alpha_s$ from 15 methods where high precision measurements are (or will be) available. Those include low-energy observables: (i) lattice QCD, (ii) pion decay factor, (iii) quarkonia and (iv) $\\tau$ decays, (v) soft parton-to-hadron fragmentation functions, as well as high-energy observables: (vi) global fits of parton distribution functions, (vii) hard parton-to-hadron fragmentation functions, (viii) jets in $e^\\pm$p DIS and $\\gamma$-p photoproduction, (ix) photon structure function in $\\gamma$-$\\gamma$, (x) event shapes and (xi) jet cross sections in $e^+e^-$ collisions, (xii) W boson and (xiii) Z boson decays, and (xiv) jets and (xv) top-quark cross sections in proton-(anti)proton collisions. The current status of the theoretical and experiment...

  14. Single beam collective effects in FCC-ee due to beam coupling impedance

    CERN Document Server

    Belli, Eleonora; Persichelli, Serena; Zobov, Mikhail

    2016-01-01

    The Future Circular Collider study, hosted by CERN to design post-LHC particle accelerator options in a worldwide context, is focused on proton-proton high-energy and electron-positron high-luminosity frontier machines. This new accelerator complex represents a great challenge under several aspects, which involve R&D on beam dynamics and new technologies. One very critical point in this context is represented by collective effects, generated by the interaction of the beam with self-induced electromagnetic fields, called wake fields, which could produce beam instabilities, thus reducing the machines performance and limiting the maximum stored current. It is therefore very important to be able to predict these effects and to study in detail potential solutions to counteract them. In this paper the resistive wall and some other important geometrical sources of impedance for the FCC electron-positron accelerator are identified and evaluated, and their impact on the beam dynamics, which in some cases could lea...

  15. Size dependence of structural parameters in fcc and hcp Ru nanoparticles, revealed by Rietveld refinement analysis of high-energy X-ray diffraction data.

    Science.gov (United States)

    Song, Chulho; Sakata, Osami; Kumara, Loku Singgappulige Rosantha; Kohara, Shinji; Yang, Anli; Kusada, Kohei; Kobayashi, Hirokazu; Kitagawa, Hiroshi

    2016-08-10

    To reveal the origin of the CO oxidation activity of Ruthenium nanoparticles (Ru NPs), we structurally characterized Ru NPs through Rietveld refinement analysis of high-energy X-ray diffraction data. For hexagonal close-packed (hcp) Ru NPs, the CO oxidation activity decreased with decreasing domain surface area. However, for face-centered cubic (fcc) Ru NPs, the CO oxidation activity became stronger with decreasing domain surface area. In comparing fcc Ru NPs with hcp Ru NPs, we found that the hcp Ru NPs of approximately 2 nm, which had a smaller domain surface area and smaller atomic displacement, showed a higher catalytic activity than that of fcc Ru NPs of the same size. In contrast, fcc Ru NPs larger than 3.5 nm, which had a larger domain surface area, lattice distortion, and larger atomic displacement, exhibited higher catalytic activity than that of hcp Ru NPs of the same size. In addition, the fcc Ru NPs had larger atomic displacements than hcp Ru NPs for diameters ranging from 2.2 to 5.4 nm. Enhancement of the CO oxidation activity in fcc Ru NPs may be caused by an increase in imperfections due to lattice distortions of close-packed planes and static atomic displacements.

  16. Thermodynamics of ordered and disordered phases in the binary Mo-Ru system

    DEFF Research Database (Denmark)

    Kissavos, A.E.; Shallcross, Sam; Kaufman, L.;

    2007-01-01

    We have performed ab initio calculations of the mixing enthalpy for the Mo-Ru alloy system. Both completely random alloys on the fcc, bcc, and hcp lattices as well as ordered and partially ordered structures based on the hcp lattice and a sigma phase have been examined. Further, we have performed...

  17. Field-Dependent Magnetic Phase Transitions in Mixed-Valent TmSe

    DEFF Research Database (Denmark)

    Bjerrum Møller, Hans; Shapiro, S. M.; Birgenau, R. J.

    1977-01-01

    A neutron diffraction study of the field-dependent magnetic ordering in TmSe is reported. The magnetic strucutre in zero field is antiferromagnetic fcc type I with TN=3.2 K. The magnetic phase diagram may be understood as a successive domain reorientation and metamagnetic transitions for T...

  18. Vacancy enhanced formation and phase transition of Cu-rich precipitates in α - iron under neutron irradiation

    Directory of Open Access Journals (Sweden)

    G. C. Lv

    2016-04-01

    Full Text Available In this paper, we employed both molecular statics and molecular dynamics simulation methods to investigate the role of vacancies in the formation and phase transition of Cu-rich precipitates in α-iron. The results indicated that vacancies promoted the diffusion of Cu atoms to form Cu-rich precipitates. After Cu-rich precipitates formed, they further trapped vacancies. The supersaturated vacancy concentration in the Cu-rich precipitate induced a shear strain, which triggered the phase transition from bcc to fcc structure by transforming the initial bcc (110 plane into fcc (111 plane. In addition, the formation of the fcc-twin structure and the stacking fault structure in the Cu-rich precipitates was observed in dynamics simulations.

  19. Vacancy enhanced formation and phase transition of Cu-rich precipitates in α - iron under neutron irradiation

    Science.gov (United States)

    Lv, G. C.; Zhang, H.; He, X. F.; Yang, W.; Su, Y. J.

    2016-04-01

    In this paper, we employed both molecular statics and molecular dynamics simulation methods to investigate the role of vacancies in the formation and phase transition of Cu-rich precipitates in α-iron. The results indicated that vacancies promoted the diffusion of Cu atoms to form Cu-rich precipitates. After Cu-rich precipitates formed, they further trapped vacancies. The supersaturated vacancy concentration in the Cu-rich precipitate induced a shear strain, which triggered the phase transition from bcc to fcc structure by transforming the initial bcc (110) plane into fcc (111) plane. In addition, the formation of the fcc-twin structure and the stacking fault structure in the Cu-rich precipitates was observed in dynamics simulations.

  20. Electronic correlations at the alpha-gamma structural phase transition in paramagnetic iron

    OpenAIRE

    Leonov, I.; Poteryaev, A. I.; Anisimov, V. I.; Vollhardt, D.

    2010-01-01

    We compute the equilibrium crystal structure and phase stability of iron at the alpha(bcc)-gamma(fcc) phase transition as a function of temperature, by employing a combination of ab initio methods for calculating electronic band structures and dynamical mean-field theory. The magnetic correlation energy is found to be an essential driving force behind the alpha-gamma structural phase transition in paramagnetic iron.

  1. Theoretical and computational comparison of models for dislocation dissociation and stacking fault/core formation in fcc crystals

    Science.gov (United States)

    Mianroodi, J. R.; Hunter, A.; Beyerlein, I. J.; Svendsen, B.

    2016-10-01

    The purpose of the current work is the theoretical and computational comparison of selected models for the energetics of dislocation dissociation resulting in stacking fault and partial dislocation (core) formation in fcc crystals as based on the (generalized) Peierls-Nabarro (GPN: e.g., Xiang et al., 2008; Shen et al., 2014), and phase-field (PF: e.g., Shen and Wang, 2004; Hunter et al., 2011, 2013; Mianroodi and Svendsen, 2015), methodologies (e.g., Wang and Li, 2010). More specifically, in the current work, the GPN-based model of Xiang et al. (2008) is compared theoretically with the PF-based models of Shen and Wang (2004), Hunter et al. (2011, 2013), and Mianroodi and Svendsen (2015). This is carried out here with the help of a unified formulation for these models via a generalization of the approach of Cahn and Hilliard (1958) to mechanics. Differences among these include the model forms for the free energy density ψela of the lattice and the free energy density ψsli associated with dislocation slip. In the PF-based models, for example, ψela is formulated with respect to the residual distortion HR due to dislocation slip (e.g., Khachaturyan, 1983; Mura, 1987), and with respect to the dislocation tensor curl HR in the GPN model (e.g., Xiang et al., 2008). As shown here, both model forms for ψela are in fact mathematically equal and so physically equivalent. On the other hand, model forms for ψsli differ in the assumed dependence on the phase or disregistry fields ϕ, whose spatial variation represents the transition from unslipped to slipped regions in the crystal. In particular, Xiang et al. (2008) and Hunter et al. (2011, 2013) work with ψsli(ϕ). On the other hand, Shen and Wang (2004) and Mianroodi and Svendsen (2015) employ ψsli(ϕ , ∇ ϕ). To investigate the consequences of these differences for the modeling of the dislocation core, dissociation, and stacking fault formation, predictions from the models of Hunter et al. (2011, 2013) and Mianroodi

  2. Structural Phase Transformation (F. C. C. - B. C. C.) in F. C. C. Metals and Their Stability on the Path of Transformation

    Science.gov (United States)

    Öztekýn, Yasemin; Çolakoðlu, Kemal

    1997-08-01

    Because of its importance in Solid-State Physics, Metalurgy, Solid Mechanics and geophysics, theoretical strength calculations are performed to locate the stress-free b.c.c phase on three f.c.c metals (Ca, Pb, Ir). Internal energies correspponding to the unstresed b.c.c. and f.c.c. phase, and the required stress and energy changes for f.c.c.-b.c.c. transformation for these crystals are computed. To determine the range of stability (G stability), the Born criterion is used by calculating the values of deformation connecting the stress-free b.c.c. and stress-free f.c.c. phases of Ca, Pb and Ir. The studied crystals are subjected to unconstrained (100) uniaxial tension in all computations, and E.G.E.P. (Extended generalized exponantial potential) model is used to carry out these calculations.

  3. First-principle band calculation of ruthenium for various phases

    CERN Document Server

    Watanabe, S; Kai, T; Shiiki, K

    2000-01-01

    The total energies and the magnetic moments of Ru for HCP, BCC, FCC, BCT structures were calculated by using a first-principle full-potential linearized augmented plane-wave (FLAPW) method based on the generalized gradient approximation (GGA). HCP has the lowest energy among the structures calculated, which agrees with the experimental result that HCP is the equilibrium phase of Ru. The total energy of BCT Ru has the local minimum at c/a=sq root 2 (FCC) with a=5.13 au, c=7.25 au and c/a=0.83 with a=6.15 au, c=5.11 au. It is pointed out that these phases are possibly metastable. The BCC structure, which corresponds to BCT with a=c=5.78 au, is unstable because it is at a saddle point of the total energy. BCT Ru of c/a<1 has a magnetic moment at the stable volume.

  4. Dissolving, trapping and detrapping mechanisms of hydrogen in bcc and fcc transition metals

    Directory of Open Access Journals (Sweden)

    Yu-Wei You

    2013-01-01

    Full Text Available First-principles calculations are performed to investigate the dissolving, trapping and detrapping of H in six bcc (V, Nb, Ta, Cr, Mo, W and six fcc (Ni, Pd, Pt, Cu, Ag, Au metals. We find that the zero-point vibrations do not change the site-preference order of H at interstitial sites in these metals except Pt. One vacancy could trap a maximum of 4 H atoms in Au and Pt, 6 H atoms in V, Nb, Ta, Cr, Ni, Pd, Cu and Ag, and 12 H atoms in Mo and W. The zero-point vibrations never change the maximum number of H atoms trapped in a single vacancy in these metals. By calculating the formation energy of vacancy-H (Vac-Hn complex, the superabundant vacancy in V, Nb, Ta, Pd and Ni is demonstrated to be much more easily formed than in the other metals, which has been found in many metals including Pd, Ni and Nb experimentally. Besides, we find that it is most energetically favorable to form Vac-H1 complex in Pt, Cu, Ag and Au, Vac-H4 in Cr, Mo and W, and Vac-H6 in V, Nb, Ta, Pd and Ni. At last, we examine the detrapping behaviors of H atoms in a single vacancy and find that with the heating rate of 10 K/min a vacancy could accommodate 4, 5 and 6 H atoms in Cr, Mo and W at room temperature, respectively. The detrapping temperatures of all H atoms in a single vacancy in V, Nb, Ta, Ni, Pd, Cu and Ag are below room temperature.

  5. Concentration profile of jet gas in the feed injection zone of a FCC riser

    Institute of Scientific and Technical Information of China (English)

    Chenglin E; Yiping Fan; Kai Zhang; Hu Zhang

    2008-01-01

    The concentration profiles of jet gas are investigated in the feed injection zone of a cold-model FCC riser by using a hydrogen trace technique.Experimental results demonstrate that four types of jet gas concentration profiles can be used to describe the mixing between the jet gas and pre-lift gas in the feed injection zone.The four types are a distinct M-shaped profile for weak mixing,an indistinct Mshaped profile for medium mixing,a sharp profile for strong mixing,and a parabolic profile for full mixing.The heights for regions of initial and full mixing reduce when decreasing the jet gas velocity or increasing the pre-lift gas velocity.Furthermore,the momentum ratio,Mj/Mr,(where Mj is the momentum of jet gas,Mr is the mixture momentum of pre-lift gas and solid particles) is introduced to describe the effects of gas-solid physical properties,operating conditions,and equipment configuration on the jet gas concentration distribution.The heights for regions of initial and full mixing between jet gas and pre-lift gas are found to be 0-0.375 and 0.375-0.675 m when Mj/Mr < 0.29,0.375-0.675 and 1.075-1.375 m when Mj/Mr > 0.54,and 0-0.375 and 0,675--1.075 m when Mj/Mr between 0.29 and 0.54,respectively.

  6. Evolution of undissolved phases in high-zinc content super-high strength aluminum alloy during ageing

    Institute of Scientific and Technical Information of China (English)

    张坤; 刘志义; 叶呈武; 许晓嫦; 郑青春

    2004-01-01

    The evolution of undissolved phases in the high-zinc content super-high strength aluminum alloy during ageing was investigated by means of SEM and EIS. The results show that undissolved phases of Cu-rich M(AlZnMgCu) exist in the silver-free alloy at solid-solution state. With increasing the ageing time, the precipitation of agehardening precipitates MgZn2 stimulates Zn atoms within the undissolved phases to diffuse into the matrix, and thus the Cu content in the M(AlZnMgCu) phase increases relatively. For the silver-bearing alloy, small addition of Ag promotes the formation of Ag-rich M(A1ZnMgCuAg) undissolved phases and deteriorates mechanical properties of the alloy. At the early stage of ageing, Ag content within the M(AlZnMgCuAg) phases greatly decreases due to rapid diffusing of Ag atoms into the matrix and the co-clustering of Ag and Mg atoms. As the ageing time prolonging, the precipitation of MgZn2 results in the decrease of Zn content in the undissolved phases, and the relative increase of Ag and Mg contents.

  7. Using PM(2.5) lanthanoid elements and nonparametric wind regression to track petroleum refinery FCC emissions.

    Science.gov (United States)

    Du, Li; Turner, Jay

    2015-10-01

    A long term air quality study is being conducted in Roxana, Illinois, USA, at the fenceline of a petroleum refinery. Measurements include 1-in-6 day 24-hour integrated ambient fine particulate matter (PM2.5) speciation following the Chemical Speciation Network (CSN) sampling and analysis protocols. Lanthanoid elements, some of which are tracers of fluidized-bed catalytic cracker (FCC) emissions, are also measured by inductively coupled plasma-mass spectrometry (ICP-MS) after extraction from PM2.5 using hot block-assisted acid digestion. Lanthanoid recoveries of 80-90% were obtained for two ambient particulate matter standard reference materials (NIST SRM 1648a and 2783). Ambient PM2.5 La patterns could be explained by a two-source model representing resuspended soil and FCC emissions with enhanced La/Ce ratios when impacted by the refinery. Nonparametric wind regression demonstrates that when the monitoring station was upwind of the refinery the mean La/Ce ratio is consistent with soil and when the monitoring station is downwind of the refinery the mean ratio is more than four times higher for bearings that corresponds to maximum impacts. Source apportionment modeling using EPA UNMIX and EPA PMF could not reliably apportion PM2.5 mass to the FCC emissions. However, the weight of evidence is that such contributions are small with no large episodes observed for the 164 samples analyzed. This study demonstrates the applicability of a hot block-assisted digestion protocol for the extraction of lanthanoid elements as well as insights obtained from long-term monitoring data including wind direction-based analyses.

  8. The role of equilibrium volume and magnetism on the stability of iron phases at high pressures.

    Science.gov (United States)

    Alnemrat, S; Hooper, J P; Vasiliev, I; Kiefer, B

    2014-01-29

    The present study provides new insights into the pressure dependence of magnetism by tracking the hybridization between crystal orbitals for pressures up to 600 GPa in the known hcp, bcc and fcc iron. The Birch-Murnaghan equation of state parameters are; bcc: V0 = 11.759 A(3)/atom, K0 = 177.72 GPa; hcp: V0 = 10.525 A(3)/atom, K0 = 295.16 GPa; and fcc: V0 = 10.682 A(3)/atom, K0 = 274.57 GPa. These parameters compare favorably with previous studies. Consistent with previous studies we find that the close-packed hcp and fcc phases are non-magnetic at pressures above 50 GPa and 60 GPa, respectively. The principal features of magnetism in iron are predicted to be invariant, at least up to ∼6% overextension of the equilibrium volume. Our results predict that magnetism for overextended fcc iron disappears via an intermediate spin state. This feature suggests that overextended lattices can be used to stabilize particular magnetic states. The analysis of the orbital hybridization shows that the magnetic bcc structure at high pressures is stabilized by splitting the majority and minority spin bands. The bcc phase is found to be magnetic at least up to 600 GPa; however, magnetism is insufficient to stabilize the bcc phase itself, at least at low temperatures. Finally, the analysis of the orbital contributions to the total energy provides evidence that non-magnetic hcp and fcc phases are likely more stable than bcc at core earth pressures.

  9. Numerical modelling of micro-machining of f.c.c. single crystal: Influence of strain gradients

    KAUST Repository

    Demiral, Murat

    2014-11-01

    A micro-machining process becomes increasingly important with the continuous miniaturization of components used in various fields from military to civilian applications. To characterise underlying micromechanics, a 3D finite-element model of orthogonal micro-machining of f.c.c. single crystal copper was developed. The model was implemented in a commercial software ABAQUS/Explicit employing a user-defined subroutine VUMAT. Strain-gradient crystal-plasticity and conventional crystal-plasticity theories were used to demonstrate the influence of pre-existing and evolved strain gradients on the cutting process for different combinations of crystal orientations and cutting directions. Crown Copyright © 2014.

  10. Helmholtz free energy and equation of state of an fcc crystal with the interaction of hard sphere Yukawa potential

    Directory of Open Access Journals (Sweden)

    M. Moradi

    2003-06-01

    Full Text Available  The Helmholtz free energy and equation of the state of an fcc crystal are calculated, where the interaction between the molecules is hard sphere-Yukawa potential. Here the perturbational density functional method is used. This method is introduced by Ebner and co-workers. In this method the density functional Taylor expansion is applied for the crystal configuration up to second order. And for the uniform parts an exact expression is used. The results are compared with those obtained by Monte Carlo computer simulation. The agreement is good.

  11. Fabrication of hollow spheres by dry-gel conversion and its application in the selective hydrodesulfurization of FCC gasoline.

    Science.gov (United States)

    Zhang, Jinchang; Wang, Gang; Jin, Fengying; Fang, Xiangchen; Song, Chunshan; Guo, Xinwen

    2013-04-15

    Hollow spheres were synthesized from MCM-41 solid spheres by dry-gel conversion. It was found that water amount has a major impact on the formation of hollow spheres. Transmission electron microscopy (TEM) images revealed that the hollow spheres are between 500 and 600 nm in size with a dense shell of ca. 100 nm. The synthesized hollow sphere sample was examined as a support for hydrodesulfurization catalyst. The sulfur removal was enhanced while olefin hydrogenation of FCC gasoline was suppressed, and thus, the octane value was preserved when the hollow spheres (Na type) were loaded with Ni and Mo oxides as catalyst.

  12. On the limitation of density functional theory (DFT) for the treatment of the anharmonicity in FCC metals

    Science.gov (United States)

    Seifitokaldani, Ali; Gheribi, Aïmen E.; Dollé, Mickael

    2016-12-01

    It has been already shown that the density functional theory (DFT) combined with the quasi-harmonic approximation (QHA) overestimates the specific heat capacity (and in general the thermal properties) of fcc metals. DFT + QHA seemingly shows a large anharmonic contribution to the heat capacity. However, in this article we show that this anharmonicity has no physical origin and it is a consequence of the deviation of the QHA from the Maxwell relations. We show that one can simply avoid this overestimation by enforcing the QHA method to obey the Maxwell relations throughout the thermodynamically self-consistent (TSC) method, instead of considering non-real local anharmonic effects.

  13. The most stable mono-layers of (111)-Pt (fcc) on Graphene: A first-principles GGA study

    Science.gov (United States)

    Otalora-Acevedo, J.; Rodríguez Martínez, J. A.; Moreno-Armenta, G.; Vera, E.; Takeuchi Tan, N.

    2016-08-01

    We investigate monolayers of planes (111) of Pt in the FCC structure located on graphene. The energy of formation showed that the most stable structure is √3×√3 — Pt on 2 × 2 — graphene. This system has a mismatch in the lattice constant of 0.45. The layers are completely flat, and its band structure shows that the new structure is metallic and the Dirac's cones are displaced 0.6eV above of the Fermi level. In this work we present the dependence of the enthalpy of formation of these structures and we calculated all structural parameters of their relaxation.

  14. Gas-solids separation model of a novel FCC riser terminator device: super short quick separator (SSQS)

    Institute of Scientific and Technical Information of China (English)

    Chunxi LU; Ruxin LI; Xiancheng LIU; Mingxian SHI

    2008-01-01

    The gas flow field and the separation efficiency of a novel fluid catalytic cracking (FCC) riser terminal device, named as Super Short Quick Separator (SSQS), were studied. On the basis of above investigations, a sec-tion-lateral-mixing separation model was proposed, which included both the effect of inertia and structure of gas outlet on particles capture. After final modification, the results predicted with this model could be in good agreement with the cold experimental data. According to this model, the separation efficiency of SSQS is mainly influenced by the difference between the arc radius and the center pipe radius as well as the magnitude of particle tangential velocity.

  15. Superionic to superionic phase change in water: consequences for the interiors of Uranus and Neptune

    CERN Document Server

    Wilson, Hugh F; Militzer, Burkhard

    2012-01-01

    Using density functional molecular dynamics free energy calculations, we show that the body-centered-cubic phase of superionic ice previously believed to be the only phase is in fact thermodynamically unstable compared to a novel phase with oxygen positions in fcc lattice sites. The novel phase has a lower proton mobility than the bc phase and may exhibit a higher melting temperature. We predict a transition between the two phases at a pressure of 1 +/- 0.5 Mbar, with potential consequences for the interiors of ice giants such as Uranus and Neptune.

  16. Phase transition and mechanical properties of tungsten nanomaterials from molecular dynamic simulation

    Science.gov (United States)

    Chen, L.; Fan, J. L.; Gong, H. R.

    2017-03-01

    Molecular dynamic simulation is used to systematically find out the effects of the size and shape of nanoparticles on phase transition and mechanical properties of W nanomaterials. It is revealed that the body-centered cubic (BCC) to face-centered cubic (FCC) phase transition could only happen in cubic nanoparticles of W, instead of the shapes of sphere, octahedron, and rhombic dodecahedron, and that the critical number to trigger the phase transition is 5374 atoms. Simulation also shows that the FCC nanocrystalline W should be prevented due to its much lower tensile strength than its BCC counterpart and that the octahedral and rhombic dodecahedral nanoparticles of W, rather than the cubic nanoparticles, should be preferred in terms of phase transition and mechanical properties. The derived results are discussed extensively through comparing with available observations in the literature to provide a deep understanding of W nanomaterials.

  17. Simulation of self-assembled nanopatterns in binary alloys on the fcc(111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Sebastian

    2008-07-01

    In this PhD thesis, we study the heteroepitaxial crystal growth by means of Monte Carlo simulations. Of particular interest in this work is the influence of the lattice mismatch of the adsorbates relative to the substrate on surface structures. In the framework of an off-lattice model, we consider one monolayer of adsorbate and investigate the emerging nanopatterns in equilibrium and their formation during growth. In chapter 1, a brief introduction is given, which describes the role of computer simulations in the field of the physics of condensed matter. Chapter 2 is devoted to some technical basics of experimental methods of molecular beam epitaxy and the theoretical description. Before a model for the simulation can be designed, it is necessary to make some considerations of the single processes which occur during epitaxial growth. For that purpose we look at an experimental setup and extract the main microscopic processes. Afterwards a brief overview of different theoretical concepts describing that physical procedures is given. In chapter 3, the model used in the simulations is presented. The aim is to investigate the growth of an fcc crystal in the [111] direction. In order to keep the simulation times within a feasible limit a simple pair potential, the Lennard-Jones potential, with continuous particle positions is used, which are necessary to describe effects resulting from the atomic mismatch in the crystal. Furthermore the detailed algorithm is introduced which is based on the idea to calculate the barrier of each diffusion event and to use the barriers in a rejection-free method. Chapter 4 is attended to the simulation of equilibrium. The influence of different parameters on the emerging structures in the first monolayer upon the surface, which is completely covered with two adsorbate materials, is studied. Especially the competition between binding energy and strain leads to very interesting pattern formations like islands or stripes. In chapter 5 the

  18. A GENERAL CRYSTALLOGRAPHIC MODEL OF fcc/bcc(bct) MARTENSITIC NUCLEATION AND GROWTH IN STEELS%钢中fcc/bcc(bct)马氏体形核与长大的一种晶体学模型

    Institute of Scientific and Technical Information of China (English)

    杨金波; 杨志刚; 邱冬; 张文征; 张弛; 白秉哲; 方鸿生

    2005-01-01

    将不变线理论和O点阵理论应用于fcc/bcc(bct)马氏体相变的可滑移生长界面的设计,建立了马氏体形核与长大的晶体学模型.通过模型分析表明:fcc/bcc(bct)马氏体形核与长大过程是通过(121)fcc型择优界面推移进行的,界面上的错配位错可以完成马氏体晶体学唯象理论(PTMC)要求的点阵不变变形(LID),但LID要稍滞后于界面迁移,即在马氏体形核与长大过程中推移界面新相一侧存在一未发生LID的新相薄区;当相变温度达到马氏体相变点Ms时,母相奥氏体与这一薄区的晶格常数比为√3/2,这一几何条件和Olson-Cohen形核模型中要求扩展位错层错区界面能γ≤0是等价的.

  19. Study on lattice stability in first principles of hcp-,fcc-and bcc-Sc%hcp-,fcc-和bcc-Sc晶格稳定性的第一原理研究

    Institute of Scientific and Technical Information of China (English)

    陶辉锦; 刘玲; 陈伟民; 文杰斌; 杨巧然

    2009-01-01

    分别采用第一原理总能赝势平面波的局域密度近似LDA(Local density approximation)和广义梯度近似GGA(Generalized gradient approximation)两种近似方法计算hcp-,fcc-和bcc-Sc的晶格常数、总能和态密度,并将实验值与以上两种方法以及CALPHAD方法的计算结果进行对比研究,发现采用LDA和GGA的计算结果均为△Gbcc-hcp>△Gfcc-hcp>0,与CALPHAD方法外推的结果△Gfcc-hcp>△Gbcc-hcp>0不一致.用LDA方法计算的hcp-,fcc-和bcc-Sc的晶格常数和原子体积较GGA方法的计算结果小,但总能绝对值偏大.LDA方法与GGA方法的态密度曲线形状基本一致,但LDA得到的s和p态电子占据数比GGA方法的偏小.

  20. Solid phase stability of a double-minimum interaction potential system

    Energy Technology Data Exchange (ETDEWEB)

    Suematsu, Ayumi; Yoshimori, Akira, E-mail: a.yoshimori@cmt.phys.kyushu-u.ac.jp; Saiki, Masafumi; Matsui, Jun [Department of Physics, Kyushu University, Fukuoka 812-8581 (Japan); Odagaki, Takashi [School of Science and Engineering, Tokyo Denki University, Hatoyama, Saitama 350-0394 (Japan)

    2014-06-28

    We study phase stability of a system with double-minimum interaction potential in a wide range of parameters by a thermodynamic perturbation theory. The present double-minimum potential is the Lennard-Jones-Gauss potential, which has a Gaussian pocket as well as a standard Lennard-Jones minimum. As a function of the depth and position of the Gaussian pocket in the potential, we determine the coexistence pressure of crystals (fcc and bcc). We show that the fcc crystallizes even at zero pressure when the position of the Gaussian pocket is coincident with the first or third nearest neighbor site of the fcc crystal. The bcc crystal is more stable than the fcc crystal when the position of the Gaussian pocket is coincident with the second nearest neighbor sites of the bcc crystal. The stable crystal structure is determined by the position of the Gaussian pocket. These results show that we can control the stability of the solid phase by tuning the potential function.

  1. Competition among fcc-like, double-layered flat, tubular cage, and close-packed structural motifs for medium-sized Au n (n = 21-28) clusters.

    Science.gov (United States)

    Tian, Dongxu; Zhao, Jijun

    2008-04-10

    Using density functional theory calculations, we compared four kinds of possible structural motifs of the medium-sized Aun (n = 21-28) clusters, i.e., fcc-like, double-layered flat, tubular cage, and close-packed. Our results show strong competition between those structural motifs in the medium-sized gold clusters. Aun (n = 21-23) adopt fcc-like structure owing to the high stability of tetrahedral Au20. A structural transition from fcc-like to tubular occurs at Au24, and the tubular motif continues at Au27 and Au28. Meanwhile, a double-layered flat structure was found at Au25, and a pyramid-based structure at Au26. The relationship between electronic properties and cluster geometry was also discussed.

  2. Computational simulation of the CrN - FCC structure; Simulación computacional de la estructura FCC del CrN

    Directory of Open Access Journals (Sweden)

    ALEXANDER RUDEN MUÑOZ

    2013-06-01

    Full Text Available CrN thin films were synthesized via Magnetron Sputtering deposition technique on (111 oriented Silicon substrates. Coatings were analyzed by using X-ray Diffraction (XRD and Raman spectroscopy, determining the cubic phase for the ceramic compound. Computational simulation of the CrN cubic crystallographic structure, performed by using Density Functional Theory (DFT, showed stability by the sum of Mulliquen charges equal to zero and compound hybridization with characteristic sp molecular orbitals and the identification of the p molecular orbital component from the nitrogen.

  3. Microstructures and mechanical properties of compositionally complex Co-free FeNiMnCr{sub 18} FCC solid solution alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Materials Science and Engineering Department, University of Tennessee, Knoxville, TN 37996 (United States); Bei, H., E-mail: beih@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2015-07-29

    Recently, a structurally-simple but compositionally-complex FeNiCoMnCr high entropy alloy was found to have excellent mechanical properties (e.g., high strength and ductility). To understand the potential of using high entropy alloys as structural materials for advanced nuclear reactor and power plants, it is necessary to have a thorough understanding of their structural stability and mechanical properties degradation under neutron irradiation. This requires us to develop a similar model alloy without Co because material with Co will make post-neutron-irradiation testing difficult due to the production of the {sup 60}Co radioisotope. To achieve this goal, a FCC-structured single-phase alloy with a composition of FeNiMnCr{sub 18} was successfully developed. This near-equiatomic FeNiMnCr{sub 18} alloy has good malleability and its microstructure can be controlled by thermomechanical processing. By rolling and annealing, the as-cast elongated-grained-microstructure is replaced by homogeneous equiaxed grains. The mechanical properties (e.g., strength and ductility) of the FeNiMnCr{sub 18} alloy are comparable to those of the equiatomic FeNiCoMnCr high entropy alloy. Both strength and ductility increase with decreasing deformation temperature, with the largest difference occurring between 293 and 77 K. Extensive twin-bands which are bundles of numerous individual twins are observed when it is tensile-fractured at 77 K. No twin bands are detected by EBSD for materials deformed at 293 K and higher. The unusual temperature-dependencies of UTS and uniform elongation could be caused by the development of the dense twin substructure, twin-dislocation interactions and the interactions between primary and secondary twinning systems which result in a microstructure refinement and hence cause enhanced strain hardening and postponed necking.

  4. Generation and enumeration of compact conformations on the two-dimensional triangular and three-dimensional fcc lattices

    Science.gov (United States)

    Peto, Myron; Sen, Taner Z.; Jernigan, Robert L.; Kloczkowski, Andrzej

    2007-07-01

    We enumerated all compact conformations within simple geometries on the two-dimensional (2D) triangular and three-dimensional (3D) face centered cubic (fcc) lattice. These compact conformations correspond mathematically to Hamiltonian paths and Hamiltonian circuits and are frequently used as simple models of proteins. The shapes that were studied for the 2D triangular lattice included m ×n parallelograms, regular equilateral triangles, and various hexagons. On the 3D fcc lattice we generated conformations for a limited class of skewed parallelepipeds. Symmetries of the shape were exploited to reduce the number of conformations. We compared surface to volume ratios against protein length for compact conformations on the 3D cubic lattice and for a selected set of real proteins. We also show preliminary work in extending the transfer matrix method, previously developed by us for the 2D square and the 3D cubic lattices, to the 2D triangular lattice. The transfer matrix method offers a superior way of generating all conformations within a given geometry on a lattice by completely avoiding attrition and reducing this highly complicated geometrical problem to a simple algebraic problem of matrix multiplication.

  5. Neon helium mixtures as a refrigerant for the FCC beam screen cooling: comparison of cycle design options

    Science.gov (United States)

    Kloeppel, S.; Quack, H.; Haberstroh, C.; Holdener, F.

    2015-12-01

    In the course of the studies for the next generation particle accelerators, in this case the Future Circular Collider for hadron-hadron interaction (FCC-hh), different aspects are being investigated. One of these is the heat load on the beam screen, which results mainly from the synchrotron radiation. In case of the FCC-hh, a heat load of 6 MW is expected. The heat has to be absorbed at 40 to 60 K due to vacuum restrictions. In this range, refrigeration is possible with both helium and neon. Our investigations are focused on a mixed refrigerant of these two components, which combines the advantages of both. Especially promising is the possible substitution of the oil flooded screw compressors by more efficient turbo compressors. This paper investigates different flow schemes and mixture compositions with respect to complexity and efficiency. Furthermore, thermodynamic aspects, e.g. whether to use cold or warm secondary cycle compressors are discussed. Additionally, parameters of the main compressor are established.

  6. Temperature-dependent ideal strength and stacking fault energy of fcc Ni: a first-principles study of shear deformation.

    Science.gov (United States)

    Shang, S L; Wang, W Y; Wang, Y; Du, Y; Zhang, J X; Patel, A D; Liu, Z K

    2012-04-18

    Variations of energy, stress, and magnetic moment of fcc Ni as a response to shear deformation and the associated ideal shear strength (τ(IS)), intrinsic (γ(SF)) and unstable (γ(US)) stacking fault energies have been studied in terms of first-principles calculations under both the alias and affine shear regimes within the {111} slip plane along the and directions. It is found that (i) the intrinsic stacking fault energy γ(SF) is nearly independent of the shear deformation regimes used, albeit a slightly smaller value is predicted by pure shear (with relaxation) compared to the one from simple shear (without relaxation); (ii) the minimum ideal shear strength τ(IS) is obtained by pure alias shear of {111}; and (iii) the dissociation of the 1/2[110] dislocation into two partial Shockley dislocations (1/6[211] + 1/6[121]) is observed under pure alias shear of {111}. Based on the quasiharmonic approach from first-principles phonon calculations, the predicted γ(SF) has been extended to finite temperatures. In particular, using a proposed quasistatic approach on the basis of the predicted volume versus temperature relation, the temperature dependence of τ(IS) is also obtained. Both the γ(SF) and the τ(IS) of fcc Ni decrease with increasing temperature. The computed ideal shear strengths as well as the intrinsic and unstable stacking fault energies are in favorable accord with experiments and other predictions in the literature.

  7. Energy of the Isolated Metastable Iron-Nickel FCC Nanocluster with a Carbon Atom in the Tetragonal Interstice.

    Science.gov (United States)

    Bondarenko, Natalya V; Nedolya, Anatoliy V

    2017-12-01

    The energy of the isolated iron-nickel nanocluster was calculated by molecular mechanics method using Lennard-Jones potential. The cluster included a carbon atom that drifted from an inside octahedral interstice to a tetrahedral interstice in [Formula: see text] direction and after that in direction to the surface. In addition, one of 14 iron atoms was replaced by a nickel atom, the position of which was changing during simulation.The energy of the nanocluster was estimated at the different interatomic distances. As a result of simulation, the optimal interatomic distances of Fe-Ni-C nanocluster was chosen for the simulation, in which height of the potential barrier was maximal and face-centered cubic (FCC) nanocluster was the most stable.It is shown that there were three main positions of a nickel atom that significantly affected nanocluster's energy.The calculation results indicated that position of the carbon atom in the octahedral interstice was more energetically favorable than tetrahedral interstice in the case of FCC nanocluster. On the other side, the potential barrier was smaller in the direction [Formula: see text] than in the direction .This indicates that there are two ways for carbon atom to drift to the surface of the nanocluster.

  8. Structure analyses of Cu nanoclusters in the soft magnetic Fe85.2Si1B9P4Cu0.8 alloy by XAFS and fcc cluster model

    Science.gov (United States)

    Matsuura, M.; Nishijima, M.; Konno, K.; Ofuchi, H.; Takenaka, K.; Makino, A.

    2016-05-01

    Size of the clusters and structure details of fcc Cu clusters in nanocrystalline soft magnetic alloy of Fe85-86Si1-2B8P4Cu1 (NANOMET) are investigated. A linear combination fitting of XAFS data indicates that about 30% of Cu atoms are partitioned in the fcc clusters and the rest in the amorphous matrix. EXAFS of the fcc Cu nanocluster embedded in amorphous matrix is calculated on the basis of a simple fcc structure model using FEFF9. Surface effect of the nanoclusters is considered by counting a fraction of the nearest neighbour atoms in amorphous matrix. Good agreement with the experimental result is obtained for the fcc nanocluster with 9 coordination shells which consists of total 177 atoms within 1.5 nm in a diameter.

  9. A new nanoscale metastable iron phase in carbon steels

    Science.gov (United States)

    Liu, Tianwei; Zhang, Danxia; Liu, Qing; Zheng, Yanjun; Su, Yanjing; Zhao, Xinqing; Yin, Jiang; Song, Minghui; Ping, Dehai

    2015-01-01

    Metastable ω phase is common in body-centred cubic (bcc) metals and alloys, including high-alloying steels. Recent theoretical calculations also suggest that the ω structure may act as an intermediate phase for face-centred cubic (fcc)-to-bcc transformation. Thus far, the role of the ω phase played in fcc-bcc martensitic transformation in carbon steels has not been reported. In previous investigations on martensitic carbon steels, extra electron diffraction spots were frequently observed by transmission electron microscopy (TEM), and these spots were historically ascribed to the diffraction arising from either internal twins or carbides. In this paper, an intensive TEM investigation revealed that the extra spots are in fact attributed to the metastable ω phase in particle-like morphology with an overall size of several or dozens of nanometres. The strict orientation relationships between the ω phase and the ferrite matrix are in good agreement with those of the hexagonal (P6/mmm) ω phase in other bcc metals and alloys. The identification of the ω phase as well as the extra diffraction spots might provide a clue to help understand the physical mechanism of martensitic transformation in steels. PMID:26503890

  10. 3D simulation of the catalyst density radial distribution in a riser of the FCC unit; Simulacao 3D da distribuicao radial de densidade do catalisador num riser de uma unidade de FCC

    Energy Technology Data Exchange (ETDEWEB)

    Apolonio, Adelia M.; Santos, Valdemir A. dos; Finkler, Christine L.L. [Universidade Catolica de Pernambuco (UNICAP), Recife, PE (Brazil); Dantas, Carlos C. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear

    2008-07-01

    Local variations in the catalyst/vacuum gas oils mixing can lead to low conversions in some parts of a fluid cracking catalytic riser, while in other parts, high conversions will produce undesirable fuel gas and coke quantities. Knowledge of the apparent solid concentration in a cross-section of the riser is then essential. A computational program to generate tri dimensional graphics and level curves of the radial catalyst density in FCC risers was elaborated. The algorithm is based on determinations of the polynomial coefficients with aid of least square method and was tested with literature data, obtained by applications of nuclear technique of gamma radiation attenuation. The simulation results showed convergence with the experimental data. The precision of the mapping depends on the number of measurements and promote better conditions of diagnostic of the distribution catalyst type in the riser. (author)

  11. Nucleation of liquid droplets and voids in a stretched Lennard-Jones fcc crystal.

    Science.gov (United States)

    Baidakov, Vladimir G; Tipeev, Azat O

    2015-09-28

    The method of molecular dynamics simulation has been used to investigate the phase decay of a metastable Lennard-Jones face-centered cubic crystal at positive and negative pressures. It is shown that at high degrees of metastability, crystal decay proceeds through the spontaneous formation and growth of new-phase nuclei. It has been found that there exists a certain boundary temperature. Below this temperature, the crystal phase disintegrates as the result of formation of voids, and above, as a result of formation of liquid droplets. The boundary temperature corresponds to the temperature of cessation of a crystal-liquid phase equilibrium when the melting line comes in contact with the spinodal of the stretched liquid. The results of the simulations are interpreted in the framework of classical nucleation theory. The thermodynamics of phase transitions in solids has been examined with allowance for the elastic energy of stresses arising owing to the difference in the densities of the initial and the forming phases. As a result of the action of elastic forces, at negative pressures, the boundary of the limiting superheating (stretching) of a crystal approaches the spinodal, on which the isothermal bulk modulus of dilatation becomes equal to zero. At the boundary of the limiting superheating (stretching), the shape of liquid droplets and voids is close to the spherical one.

  12. Effect of the operating variables of a fluid catalytic cracking unit (FCC) on the naphtha gum formation; Efeito das variaveis operacionais de uma unidade de craqueamento catalitico (FCC) na formacao da goma na nafta

    Energy Technology Data Exchange (ETDEWEB)

    Mattos, Leandro Generoso de [PETROBRAS, Betim, MG (Brazil). Unidade de Negocio Refinaria Gabriel Passos (REGAP). Gerencia de Hidrotratamento e Coque]. E-mail: leandrogm@petrobras.com.br; Almeida, Gustavo Matheus de [Universidade de Sao Paulo (USP), SP (Brazil). Escola Politecnica. Dept. de Engenharia Quimica]. E-mail: gustavo@lscp.pqi.ep.usp.br; Oliveira, Eder Domingos de; Cardoso, Marcelo [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Quimica]. E-mails: eder@deq.ufmg.br; mcardoso@deq.ufmg.br

    2006-12-15

    One of the main problems brought by gasoline combustion in vehicles is the deposition of gum in the fuel system. Gum, though soluble in gasoline, appears in the form of a viscous residue after gasoline has evaporated. The carbon deposits coating carburetors, nozzles, collector pipes, intake valves and combustion chambers affect the car's steering capacity, lower the engine's performance and increase the emission of exhaust gas. Given the sort of refining used in Brazil, the content of naphtha resulting from catalytic cracking in gasoline coming from refineries is quite significant. The chains resulting from catalytic or thermal cracking processes have a strong tendency to form gum. In Fluid Catalytic Cracking (FCC), a complex network of chemical reactions takes place, which can either be catalytic or thermal. Principal Component Analysis techniques (PCA), stepwise regression and genetic algorithms have been used to select the operating variables of FCC that will bear the most influence on gum formation. An ARN (Artificial Neural Networks) software tool was also used to anticipate gum forming from operating variables selected by means of the above mentioned techniques. The results achieved in forecasting gum forming in cracked naphtha lead us to believe that the data analysis methodology used was suitable. It is possible to forecast potential gum through seven variables with a 10% Mean Relative Error (MRE) and a 1.75 g/100 mL Mean Absolute Error (MAE) with a linear correlation coefficient of 0.844; or through eight variables with an 11% MRE and a 1.93 g/100 mL MAE with a linear correlation coefficient of 0.829. In the first case, the methodology employed to reduce variables was stepwise regression, and in the second, genetic algorithms. (author)

  13. Phase stabilities and spinodal decomposition in the Cr{sub 1-x}Al {sub x}N system studied by ab initio LDA and thermodynamic modeling: Comparison with the Ti{sub 1-x}Al {sub x}N and TiN/Si{sub 3}N{sub 4} systems

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, R.F. [Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, D-85747 Munich (Germany); Veprek, S. [Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, D-85747 Munich (Germany)]. E-mail: veprek@ch.tum.de

    2007-08-15

    The total energies and lattice constants of binary hexagonal close-packed (hcp)- and face-centered cubic (fcc)-CrN, AlN and ternary Cr{sub 0.5}Al{sub 0.5}N phases are calculated using the Vienna Ab-initio Simulation Program. The calculated total energies of the structures are then used to calculate the lattice stabilities of binary hcp- and fcc-CrN and AlN, and the interaction parameters of the ternary hcp- and fcc-Cr{sub 1-x}Al {sub x}N solution phases. These results are used in the sublattice thermodynamic model to construct the Gibbs free energy diagram of the immiscible quasi-binary CrN-AlN system at different temperatures. Based on these results, we discuss the relative phase stability of the metastable ternary hcp- and fcc-Cr{sub 1-x}Al {sub x}N solid solutions over the entire range of compositions. The predictions are compared with and supported by the published results from physical and chemical vapor deposition experiments. The constructed Gibbs free energy diagrams show that metastable fcc-Cr{sub 1-x}Al {sub x}N coatings may undergo spinodal decomposition into coherent fcc-CrN and fcc-AlN, but there is a relatively large barrier for a direct formation of the stable hcp-AlN. A comparison with the Ti{sub 1-x}Al {sub x}N and TiN-Si{sub 3}N{sub 4} systems shows that the phase segregation will be more difficult and, therefore, the solid solution more stable in the Cr{sub 1-x}Al {sub x}N case.

  14. Analysis of the fluid-bed stability of FCC catalysts at high temperature in terms of bed elasticity

    Institute of Scientific and Technical Information of China (English)

    Paola Lettieri; Luca Mazzer

    2008-01-01

    The effect of temperature on the fluid-bed stability of three FCC catalysts has been analyzed through considerations on fluid-bed elasticity. Experimental findings on the effect of temperature on the elasticity modulus at minimum bubbling conditions, (E)mb, were analyzed using the hydrodynamic fluid-bed stability model developed by Foscolo and Gibilaro (1984) and adopting the interparticle-forces-based stability criterion developed by Mutsers and Rietema (1977). For both models, the parameters which control changes in (E)mb with temperature are discussed, in order to establish the origin of the fluid-bed elasticity and analyze the ability of these models to discriminate between the relative importance of the hydrodynamic and interparticle forces on the stability of the fluidized catalysts.

  15. Dynamics of Edge Dislocations in a Low-Stability FCC-System Irradiated by High-Energy Particles

    Science.gov (United States)

    Starostenkov, M. D.; Potekaev, A. I.; Markidonov, A. V.; Kulagina, V. V.; Grinkevich, L. S.

    2017-01-01

    Using the method of molecular dynamics, the behavior of plastic deformation and defect structure selforganization are investigated in a low-stability condensed FCC-system irradiated with high-energy particles. An analysis of the dynamics of a single edge dislocation and elementary dislocation ensembles, subjected to the action of a post-cascade shock wave, demonstrates that as a result of this action the dislocations are displaced towards the wave source. As this goes on, the roles of both collective effects and external influences on the ensembles of complex interacting defects increase. In particular, the investigation performed in this work demonstrates that the post-cascade shock waves can give rise to migration of not only single edge dislocation but also elementary dislocation ensembles. It is demonstrated that the changes in the dislocation structure of the irradiated material result from the unloading waves following the post-cascade waves, rather than from the latter waves themselves.

  16. Growth of fcc(111) Dy multi-height islands on 6H-SiC(0001) graphene.

    Science.gov (United States)

    Hershberger, M T; Hupalo, M; Thiel, P A; Tringides, M C

    2013-06-05

    Graphene based spintronic devices require an understanding of the growth of magnetic metals. Rare earth metals have large bulk magnetic moments so they are good candidates for such applications, and it is important to identify their growth mode. Dysprosium was deposited on epitaxial graphene, prepared by thermally annealing 6H-SiC(0001). The majority of the grown islands have triangular instead of hexagonal shapes. This is observed both for single layer islands nucleating at the top of incomplete islands and for fully completed multi-height islands. We analyze the island shape distribution and stacking sequence of successively grown islands to deduce that the Dy islands have fcc(111) structure, and that the triangular shapes result from asymmetric barriers to corner crossing.

  17. Phase transitions in antiferromagnets with a NaCl structure

    Energy Technology Data Exchange (ETDEWEB)

    Kassan-Ogly, F.A. [Institute of Metal Physics, Ural Division, Russian Academy of Sciences, ul. S.Kovalevskoi 18, Ekaterinburg 620219 (Russian Federation)]. E-mail: felix.kassan-ogly@imp.uran.ru; Filippov, B.N. [Institute of Metal Physics, Ural Division, Russian Academy of Sciences, ul. S.Kovalevskoi 18, Ekaterinburg 620219 (Russian Federation)

    2006-05-15

    A revised derivation scheme of possible magnetic structures in an FCC lattice with the nearest- and next-nearest-neighbor interactions taken into account is proposed. A model of simultaneous magnetic and structural phase transitions of the first order is developed for antiferromagnets with a NaCl structure and with a strong cubic magnetic anisotropy on the base of synthesis of magnetic modified 6-state Potts model and theoretical models of structural phase transitions in cubic crystals. It is shown that the high-temperature diffuse magnetic scattering of neutrons transforms into magnetic Bragg reflections below Neel point.

  18. Phase transitions in antiferromagnets with a NaCl structure

    Science.gov (United States)

    Kassan-Ogly, F. A.; Filippov, B. N.

    2006-05-01

    A revised derivation scheme of possible magnetic structures in an FCC lattice with the nearest- and next-nearest-neighbor interactions taken into account is proposed. A model of simultaneous magnetic and structural phase transitions of the first order is developed for antiferromagnets with a NaCl structure and with a strong cubic magnetic anisotropy on the base of synthesis of magnetic modified 6-state Potts model and theoretical models of structural phase transitions in cubic crystals. It is shown that the high-temperature diffuse magnetic scattering of neutrons transforms into magnetic Bragg reflections below Néel point.

  19. CRYSTALLISATION KINETICS AND PHASE TRANSFORMATION BEHAVIOUR OF ELECTROLESS NICKEL-PHOSPHORUS DEPOSIT WITH 6-9wt% PHOSPHORUS CONTENT

    Institute of Scientific and Technical Information of China (English)

    K.G. Keong; W. Sha; S. Malinov

    2001-01-01

    Crystallisation kinetic and phase transformation behaviour of the electroless nicke l-phosphorus deposit with 6-9wt% phosphorus content were studied. The deposit washeated in the differential scanning calorimetry (DSC) apparatus to 300℃ 800℃ at20℃/rain, followed by the X-ray diffraction (XRD) analysis. The sequence of cwstallisation process was: mixture of amorphous and microcrystalline nickel phases →intermediate metastable, f.c.c, nickel and stable Ni3P phasesf.c.c, nickel and sta-ble Ni3P phases. Preferred orientation of nickel { 200} plane was developed after theheating processes. Activation energy of crystallisation process was determined fromthe DSC analyses at 5-50℃/min. Crystallisation temperatures were found increasedwith increasing heating rate.

  20. Frustrated fcc antiferromagnet Ba2YOsO6 : Structural characterization, magnetic properties, and neutron scattering studies

    Science.gov (United States)

    Kermarrec, E.; Marjerrison, C. A.; Thompson, C. M.; Maharaj, D. D.; Levin, K.; Kroeker, S.; Granroth, G. E.; Flacau, R.; Yamani, Z.; Greedan, J. E.; Gaulin, B. D.

    2015-02-01

    We report the crystal structure, magnetization, and neutron scattering measurements on the double perovskite Ba2YOsO6 . The F m 3 ¯m space group is found both at 290 K and 3.5 K with cell constants a0=8.3541 (4 ) Å and 8.3435 (4 ) Å, respectively. Os5 + (5 d3 ) ions occupy a nondistorted, geometrically frustrated face-centered-cubic (fcc) lattice. A Curie-Weiss temperature θ ˜-700 K suggests the presence of a large antiferromagnetic interaction and a high degree of magnetic frustration. A magnetic transition to long-range antiferromagnetic order, consistent with a type-I fcc state below TN˜69 K, is revealed by magnetization, Fisher heat capacity, and elastic neutron scattering, with an ordered moment of 1.65(6) μB on Os5 +. The ordered moment is much reduced from either the expected spin-only value of ˜3 μB or the value appropriate to 4 d3 Ru5 + in isostructural Ba2YRuO6 of 2.2(1) μB, suggesting a role for spin-orbit coupling (SOC). Triple-axis neutron scattering measurements of the order parameter suggest an additional first-order transition at T =67.45 K, and the existence of a second-ordered state. Time-of-flight inelastic neutron results reveal a large spin gap Δ ˜17 meV, unexpected for an orbitally quenched, d3 electronic configuration. We discuss this in the context of the ˜5 meV spin gap observed in the related Ru5 +,4 d3 cubic double perovskite Ba2YRuO6 , and attribute the ˜3 times larger gap to stronger SOC present in this heavier, 5 d , osmate system.

  1. 采用P507(HEH/EHP)从废FCC催化剂中回收稀土%Recycling rare earth from spent FCC catalyst using P507 (HEH/EHP) as extractant

    Institute of Scientific and Technical Information of China (English)

    何捍卫; 孟佳

    2011-01-01

    废FCC催化剂(废石油催化炼化催化剂)中含有2%以上的富La或富Ce稀土,用盐酸浸取后可得到含有稀土元素和非稀土杂质的氯化稀土溶液.研究用P507(2-乙基己基膦酸单-2-乙基己基酯,HEH/EHP)从盐酸介质中萃取稀土的工艺方法,考察萃取分离稀土的主要影响因素.试验结果表明:可以从P507-煤油-盐酸体系中有效地萃取出稀土元素,较好地实现稀土元素和非稀土杂质的分离,其较优工艺条件为:萃取剂浓度(P507体积分数)为60%,浸取液pH为2.5,萃取相比为2:1,萃取平衡时间为30 min;负载有机相直接用盐酸进行反萃得到氯化稀土溶液,反萃盐酸浓度为2.0 mol/L,反萃平衡时间为60 min.该方法工艺简单,解决了废FCC催化剂的处理问题,减少对环境的污染,同时也回收稀土金属.%Spent FCC catalyst contains more than 2% rare earth (RE) elements rich of lanthanum or cerium, and solution of rare earth chloride containing rare earth elements and non-RE impurity was obtained after leaching with hydrochloric acid. Extracting rare earth elements La and Ce from hydrochloric acid system by P507 (2-ethylhexyl phosphonic acid mono 2-ethylhexyl, HEH/EHP) was studied, and the influence on the extraction and separation of rare earth was researched. The results show that rare earth can be extracted effectively from P507-kerosene-HCl extraction separation of rare earth and non-RE impurity was achieved. The technological conditions are as follows: extractant concentration (volume concentration of PSO7) is 60%, the pH of leaching solution is 2.5, the volume ratio of organic phase and water phase is 2:1, and the equilibrium time of extraction is 30 min. Then the solution of rare earth chloride from loaded organic phase can be back-extracted using hydrochloric acid. The back-extract concentration of hydrochloric acid is 2.0 mol/L, and the equilibrium time of back extraction is 60 min. The whole experimental route is simple and the

  2. Atomic scale analysis of phase formation and diffusion kinetics in Ag/Al multilayer thin films

    Science.gov (United States)

    Aboulfadl, Hisham; Gallino, Isabella; Busch, Ralf; Mücklich, Frank

    2016-11-01

    Thin films generally exhibit unusual kinetics leading to chemical reactions far from equilibrium conditions. Binary metallic multilayer thin films with miscible elements show some similar behaviors with respect to interdiffusion and phase formation mechanisms. Interfacial density, lattice defects, internal stresses, layer morphologies and deposition conditions strongly control the mass transport between the individual layers. In the present work, Ag/Al multilayer thin films are used as a simple model system, in which the effects of the sputtering power and the bilayer period thickness on the interdiffusion and film reactions are investigated. Multilayers deposited by DC magnetron sputtering undergo calorimetric and microstructural analyses. In particular, atom probe tomography is extensively used to provide quantitative information on concentration gradients, grain boundary segregations, and reaction mechanisms. The magnitude of interdiffusion was found to be inversely proportional to the period thickness for the films deposited under the same conditions, and was reduced using low sputtering power. Both the local segregation at grain boundaries as well as pronounced non-equilibrium supersaturation effects play crucial roles during the early stages of the film reactions. For multilayers with small periods of 10 nm supersaturation of the Al layers with Ag precedes the polymorphic nucleation and growth of the hcp γ-Ag2Al phase. In larger periods the γ phase formation is triggered at junctions between grain boundaries and layers interfaces, where the pathway to heterogeneous nucleation is local supersaturation. Other Ag-rich phases also form as intermediate phases due to asymmetric diffusion rates of parent phases in the γ phase during annealing.

  3. A UNIVERSAL ANALYTIC POTENTIAL-ENERGY FUNCTION BASED ON A PHASE FACTOR

    Institute of Scientific and Technical Information of China (English)

    C.F. Yu; K. Yan; D.Z. Liu

    2006-01-01

    Using a field equation with a phase factor, a universal analytic potential-energy function applied to the interactions between diatoms or molecules is derived, and five kinds of potential curves of common shapes are obtained adjusting the phase factors. The linear thermal expansion coefficients and Young's moduli of eleven kinds of fuce-centered cubic (fcc) metals - Al, Cu, Ag, etc. Are calculated using the potential-energy function; the computational results are quite consistent with experimental values. Moreover, an analytic relation between the linear thermal expansion coefficients and Young's moduli of fcc metals is given using the potential-energy function. Finally, the force constants of fifty-five kinds of diatomic moleculars with low excitation state are computed using this theory, and they are quite consistent with RKR (Rydberg-Klein-Rees) experimental values.

  4. Effect of shear on cubic phases in gels of a diblock copolymer

    DEFF Research Database (Denmark)

    Hamley, I.W.; Pople, J.A.; Fairclough, J.P.A.;

    1998-01-01

    The effect of shear on the orientation of cubic micellar phases formed by a poly(oxyethylene)poly(oxybutylene) diblock copolymer in aqueous solution has been investigated using small-angle x-ray scattering (SAXS) and small-angle neutron scattering (SANS). SAXS was performed on samples oriented in...... to form a macroscopically oriented domain. Shear only homogenized the sample, producing a powder SAXS pattern from a fcc structure....

  5. Solid solution or amorphous phase formation in TiZr-based ternary to quinternary multi-principal-element films

    Directory of Open Access Journals (Sweden)

    Mariana Braic

    2014-08-01

    The deposited films exhibited only solid solution (fcc, bcc or hcp or amorphous phases, no intermetallic components being detected. It was found that the hcp structure was stabilized by the presence of Hf or Y, bcc by Nb or Al and fcc by Cu. For the investigated films, the atomic size difference, mixing enthalpy, mixing entropy, Gibbs free energy of mixing and the electronegativity difference for solid solution and amorphous phases were calculated based on Miedema׳s approach of the regular solution model. It was shown that the atomic size difference and the ratio between the Gibbs free energies of mixing of the solid solution and amorphous phases were the most significant parameters controlling the film crystallinity.

  6. Stability of ordered phases in block copolymer melts and solutions

    Indian Academy of Sciences (India)

    Kell Mortensen

    2008-11-01

    Block copolymer melts and solutions assemble into nanosized objects that order into a variety of phases, depending on molecular parameters and mutual interactions. Beyond the classical phases of lamella ordered sheets, hexagonally ordered cylinders and cubic ordered spheres, the complex bicontinuous gyroid phase and the modulated lamellar phase are observed near the phase boundaries. The stability of these phases has been discussed on the basis of theoretical calculations. Here, we will discuss new experimental results showing that the given ordered phase depends critically on both molecular purity and mechanical treatment of the sample. While a variety of block copolymer micellar systems have been shown to undergo the liquid-to-bcc-to-fcc phase sequence upon varying micellar parameters (or temperature), we find for a purified system a different sequence, namely liquid-to-fcc-to-bcc [1]. The latter sequence is by the way the one predicted for pure block copolymer melts. External fields like shear or stress may also affect the ordered phase. Applying well-controlled large-amplitude oscillatory shear can be used to effectively control the texture of soft materials in the ordered states. As an example, we present results on a body-centred-cubic phase of a block copolymer system, showing how a given texture can be controlled with the application of specific shear rate and shear amplitude [2,3]. Shear may however also affect the thermodynamic ground state, causing shear-induced ordering and disordering (melting), and shear-induced order–order transitions. We will present data showing that the gyroid state of diblock copolymer melts is unstable when exposed to large amplitude/frequency shear, transforming into the hexagonal cylinder phase [4]. The transformation is completely reversible. With the rather slow kinetics in the transformation of copolymer systems, it is possible in detail to follow the complex transformation process, where we find transient ordered

  7. Microstructural Characterization of Dislocation Networks During Harper-Dorn Creep of fcc, bcc, and hcp Metals and Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Przystupa, Marek A.

    2007-12-13

    Harper-Dorn (H-D) creep is observed in metals and geological materials exposed to very low stresses at temperatures close to the melting point. It is one of several types of creep processes wherein the steady-state strain rate is proportional to the applied stress, Nabarro-Herring creep and Coble creep being two other important processes. H-D creep can be somewhat insidious because the creep rates are much larger than those expected for Nabarro-Herring or Coble creep. Since the working conditions of structural components of power plants and propulsion systems, as well as the motion of the earth’s mantle all involve very low stresses, an understanding of the factors controlling H-D creep is critical in preventing failures associated with those higher-than-expected creep rates. The purpose of this investigation was to obtain missing microstructural information on the evolution of the dislocation structures during static annealing of materials with fcc, bcc and hcp structure and use obtained results to test predictive capabilities of the dislocation network theory of H-D creep. In our view the evolutionary processes during static annealing and during Harper-Dorn creep are intimately related. The materials used in this study were fcc aluminum, hcp zinc and bcc tin. All characterizations of dislocation structures, densities and dislocation link length distributions were carried out using the etch pit method. To obtain quantitative information on the evolution of the dislocation networks during annealing the pure fcc aluminum samples were pre-deformed by creep at 913 and 620 K and then annealed. The higher deformation temperature was selected to generate starting dislocation networks similar to those forming during Harper-Dorn creep and the lower, to obtain higher dislocation densities suitable for reliable estimates of the parameters of the network growth law. The measured experimental link length distribution were, after scaling, (1) the same for all annealing

  8. Catalog of computer simulated TEM images of small FCC and BCC dislocation loops

    Energy Technology Data Exchange (ETDEWEB)

    Sykes, L.J.; Cooper, W.D.; Hren, J.J.

    1981-02-01

    Interest in rapidly quenched materials, radiation damage and the initial stages of phase transformations has created the need for a method to identify small strain centers observed by transmission electron microscopy. This report is an outgrowth of this general area of interest and concerns itself primarily with the images of small dislocation loops (r < 0.25 xi g). The various parameters important in determining an image are presented and a catalog of computer simulated images for a large number of loop crystallographies imaged under a large number of beam direction and diffracting vector combinations is assembled. The program which produced the images is also described and included with annotation.

  9. High-temperature γ (FCC/γ′ (L12 Co-Al-W based superalloys

    Directory of Open Access Journals (Sweden)

    Knop Matthias

    2014-01-01

    Full Text Available Interim results from the development of a polycrystalline Co-Al-W based superalloy are presented. Cr has been added to provide oxidation resistance and Ni has then been added to widen and stabilise the γ′ phase field. The alloy presented has a solvus of 1010 °C and a density of 8.7 g cm−3. The room temperature flow stress is over 1000 MPa and this reduces dramatically above 800 °C. The flow stress anomaly is observed. A microstructure with both ∼ 50 nm γ′ produced on cooling and larger 100–200 nm γ′ can be obtained. Isothermal oxidation at 800 °C in air for 200 h gave a mass gain of 0.96 mg cm−2. After hot deformation in the 650–850 °C temperature range, both anti phase boundaries (APBs and stacking faults could be observed. An APB energy of 71 mJ m−2 was measured, which is comparable to that found in commercial nickel superalloys.

  10. Proposal to negotiate three collaboration agreements in the context of the Future Circular Collider Study (FCC) concerning the development of HTS coated tapes integrated into the beam screen for impedance mitigation

    CERN Document Server

    2016-01-01

    Proposal to negotiate three collaboration agreements in the context of the Future Circular Collider Study (FCC) concerning the development of HTS coated tapes integrated into the beam screen for impedance mitigation

  11. Probing Anomalous WW γ and WWZ Couplings with Polarized Electron Beam at the LHeC and FCC-Ep Collider

    CERN Document Server

    Turk Cakir, I; Tasci, A T; Cakir, O

    2016-01-01

    We study the anomalous WWγ and WWZ couplings by calculating total cross sections of two processes at the LHeC with electron beam energy Ee=140 GeV and the proton beam energy Ep=7 TeV, and at the FCC-ep collider with the polarized electron beam energy Ee=80 GeV and the proton beam energy Ep=50 TeV. At the LHeC with electron beam polarization, we obtain the results for the difference of upper and lower bounds as (0.975, 0.118) and (0.285, 0.009) for the anomalous (∆κγ, λγ) and (∆κz, λz) couplings, respectively. As for FCC-ep collider, these bounds are obtained as (1.101, 0.065) and (0.320, 0.002) at an integrated luminosity of Lint=100 fb-1.

  12. Influence of crystallographic orientation on the magnetic properties of NiFe, Co, and Ni epitaxial fcc films grown on single-crystal substrates

    Science.gov (United States)

    Ohtani, Taiki; Kawai, Tetsuroh; Ohtake, Mitsuru; Futamoto, Masaaki

    2013-08-01

    Ni80Fe20 (at. %), Co, and Ni epitaxial thin films of fcc(100) and fcc(111) orientations are prepared on single-crystal substrates by using an ultra-high-vacuum radio-frequency magnetron sputtering system. The influence of the magnetocrystalline anisotropy on the magnetostriction behavior under in-plane rotating magnetic fields is investigated. Triangular waveforms are observed in the magnetostriction measurements under low rotating fields for films that show four-fold symmetry in the in-plane magnetic anisotropies. The magnetostriction behavior is related to the motion of ninety-degree magnetic domain walls in magnetically unsaturated films. The waveform changes from a triangular to a sinusoidal shape when magnetization saturation is approached under increasing magnetic field. On the other hand, films having almost isotropic in-plane magnetic properties show sinusoidal waveforms even when the films are not magnetically saturated.

  13. FCC再生烟气中SO3的生成及应对措施%Formation of SO3 in FCC flue gas and countermeasures

    Institute of Scientific and Technical Information of China (English)

    齐文义

    2011-01-01

    The formation mechanisms of SO3 in FCC flue gas, the impact factor and associated hazards are described. The effective measures to reduce SO3 in FCC flue gas are proposed, such as reducing regenerator main air flowrate, lowering the dosage of Pt-based CO combustion promoter, applying sulfur transfer catalyst and metal passivator and properly increasing unloading rate of catalysts.%论述了FCC再生烟气中SO的生成机理、影响因素以及所带来的危害;提出了降低FCC再生烟气中SO含量的应对措施:降低再生主风置、减少铂基CO助燃剂的使用量、使用硫转移助剂和金属钝化剂以及适当增加催化剂的卸剂量.

  14. Exotic magnetism on the quasi-fcc lattices of the d3 double Perovskites La2NaB'O6 (B'=Ru, Os).

    Science.gov (United States)

    Aczel, A A; Baker, P J; Bugaris, D E; Yeon, J; Zur Loye, H-C; Guidi, T; Adroja, D T

    2014-03-21

    We find evidence for long-range and short-range (ζ=70 Å at 4 K) incommensurate magnetic order on the quasi-face-centered-cubic (fcc) lattices of the monoclinic double perovskites La2NaRuO6 and La2NaOsO6, respectively. Incommensurate magnetic order on the fcc lattice has not been predicted by mean field theory, but may arise via a delicate balance of inequivalent nearest neighbor and next nearest neighbor exchange interactions. In the Ru system with long-range order, inelastic neutron scattering also reveals a spin gap Δ ∼ 2.75 meV. Magnetic anisotropy is generally minimized in the more familiar octahedrally coordinated 3d3 systems, so the large gap observed for La2NaRuO6 may result from the significantly enhanced value of spin-orbit coupling in this 4d(3) material.

  15. Optimizing FCC feed hydrotreating unit to produce ultra low sulfur gasoline%FCC原料加氢预处理生产超低硫汽油技术措施综述

    Institute of Scientific and Technical Information of China (English)

    刘畅; 梁家林; 高晓冬

    2016-01-01

    The impacts of ultra low sulfur gasoline (ULSG)production on existing FCC feed hydrotreating units and maj or technical choices made by many countries were summarized.The development direction and main technical strategies of the FCC feed hydrotreating process for the production of ULSG were discussed.ULSG production which require sulfur content less than 10μg/g will significantly decrease FCC feed pre-treater unit cycle lengths and increase operating costs.Main technical strategies for FCC feed hydrotreating producing ULSG are:optimizing existing FCC feed hydrotreating device,increasing a FCC feed hydrotreating reactor,increasing feeding quantity of the existing FCC feed hydrotreating unit,developing FCC feed hydrotreating-FCC combination process, building new or converting into mild hydrocracking or partial conversion hydrocracking units,building new or modifying FCC gasoline post-treat unit.%阐述了超低硫汽油的生产对现有 FCC 原料加氢预处理技术的影响以及世界各国的技术策略,并指明了FCC原料加氢预处理技术在生产超低硫汽油中的发展方向和主要技术措施。研究表明:从生产30μg/g 的清洁汽油到生产硫含量小于10μg/g的超低硫汽油会造成 FCC原料加氢预处理装置氢耗高、运转周期短、加氢预处理-催化裂化联合装置经济性差等问题。FCC原料加氢预处理生产超低硫汽油的主要技术措施有:优化现有的 FCC原料加氢预处理装置、对现有 FCC原料加氢预处理装置增加一个反应器、增加现有 FCC原料加氢预处理装置的进料量、开发FCC原料加氢预处理-FCC组合工艺、新建或改造成缓和加氢裂化装置、新建或改造成部分转化加氢裂化、新建或改造 FCC汽油后处理装置。

  16. Highly anisotropic exchange interactions of jeff=1/2 iridium moments on the fcc lattice in La2B IrO6 (B =Mg ,Zn )

    Science.gov (United States)

    Aczel, A. A.; Cook, A. M.; Williams, T. J.; Calder, S.; Christianson, A. D.; Cao, G.-X.; Mandrus, D.; Kim, Yong-Baek; Paramekanti, A.

    2016-06-01

    We have performed inelastic neutron scattering (INS) experiments to investigate the magnetic excitations in the weakly distorted face-centered-cubic (fcc) iridate double perovskites La2ZnIrO6 and La2MgIrO6 , which are characterized by A-type antiferromagnetic ground states. The powder inelastic neutron scattering data on these geometrically frustrated jeff=1/2 Mott insulators provide clear evidence for gapped spin-wave excitations with very weak dispersion. The INS results and thermodynamic data on these materials can be reproduced by conventional Heisenberg-Ising models with significant uniaxial Ising anisotropy and sizeable second-neighbor ferromagnetic interactions. Such a uniaxial Ising exchange interaction is symmetry forbidden on the ideal fcc lattice, so that it can only arise from the weak crystal distortions away from the ideal fcc limit. This may suggest that even weak distortions in jeff=1/2 Mott insulators might lead to strong exchange anisotropies. More tantalizingly, however, we find an alternative viable explanation of the INS results in terms of spin models with a dominant Kitaev interaction. In contrast to the uniaxial Ising exchange, the highly directional Kitaev interaction is a type of exchange anisotropy which is symmetry allowed even on the ideal fcc lattice. The Kitaev model has a magnon gap induced by quantum order by disorder, while weak anisotropies of the Kitaev couplings generated by the symmetry lowering due to lattice distortions can pin the order and enhance the magnon gap. Our findings highlight how even conventional magnetic orders in heavy transition metal oxides may be driven by highly directional exchange interactions rooted in strong spin-orbit coupling.

  17. Solutions for coking in settler of FCC%浅析炼油厂催化装置沉降器防结焦技改措施

    Institute of Scientific and Technical Information of China (English)

    王进; 刘强

    2015-01-01

    This article describes the mechanism of coke formation.The reasons of coking in settler of FCC unit and solutions are provided as well.%本文阐述了结焦形成的机理的类型,分析了炼油厂在使用催化装置沉降器过程中结焦的成因和沉降器的防结焦技术改进方法.

  18. Self-nanoemulsifying performance of two grades of Lauroglycol (Lauroglycol-90 and Lauroglycol-FCC) in the presence of mixed nonionic surfactants.

    Science.gov (United States)

    Shakeel, Faiyaz; Haq, Nazrul; Alanazi, Fars K; Alsarra, Ibrahim A

    2014-11-01

    The present study was undertaken to evaluate the impact of various combinations of nonionic surfactants on self-nanoemulsifying performance of two grades of Lauroglycol (Lauroglycol-90 and Lauroglycol-FCC) in glibenclamide (GBN) nanoemulsion. Formulations (L1-L30) were prepared by spontaneous emulsification method. Prepared formulations were subjected to thermodynamic stability and self-nanoemulsification test. Results of thermodynamic stability and self-nanoemulsification tests were confirmed by further characterization of these formulations in terms of droplet size, viscosity, refractive index and % transmittance. Formulations prepared with Labrasol, HCO-60 and Gelucire-44/14 were found to be suitable for self-emulsifying drug delivery system only whereas those prepared with Tween-80 and Cremophor-EL were found to be suitable for self-nanoemulsifying or self-microemulsifying drug delivery system of GBN with respect to Lauroglycol-90 or Lauroglycol-FCC. Formulation L24 (Lauroglycol-FCC/Tween-80/ethanol/water) was optimized as best formulation for self-nanoemulsifying drug delivery system of GBN. These results indicated that Tween-80 could be the best surfactant in terms of self-nanoemulsification.

  19. Zn-Mg合金的结构分析和Zn-Mg扩散体系的物相分布%Analysis of Zn-Mg Alloy Structure and Phases Distribution of Zn-Mg Diffusion System

    Institute of Scientific and Technical Information of China (English)

    高帅; 吴永全; 沈通; 张宁; 赖莉珊

    2012-01-01

    Molecular dynamics (MD) simulations usually analyze the structure of a phase by radial distribution function (RDF), the Honeycutt-Anderson (HA) bond pair analysis, and the cluster-type index method (CTIM). In this paper, we improve CTIM to allow the characterization of more kinds of crystal structure besides bcc\\fcc\\hcp\

  20. The modeling of quadratic B-splines surfaces for the tomographic reconstruction in the FCC- type-riser

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, Geovane Vitor; Dantas, Carlos Costa, E-mail: geovitor@bol.com.b, E-mail: ccd@ufpe.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear. Grupo de Radioquimica; Melo, Silvio de Barros; Pires, Renan Ferraz, E-mail: sbm@cin.ufpe.b, E-mail: rfp@cin.ufpe.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Centro de Informatica

    2009-07-01

    The 3D tomography reconstruction has been a profitable alternative in the analysis of the FCC-type- riser (Fluid Catalytic Cracking), for appropriately keeping track of the sectional catalyst concentration distribution in the process of oil refining. The method of tomography reconstruction proposed by M. Azzi and colleagues (1991) uses a relatively small amount of trajectories (from 3 to 5) and projections (from 5 to 7) of gamma rays, a desirable feature in the industrial process tomography. Compared to more popular methods, such as the FBP (Filtered Back Projection), which demands a much higher amount of gamma rays projections, the method by Azzi et al. is more appropriate for the industrial process, where the physical limitations and the cost of the process require more economical arrangements. The use of few projections and trajectories facilitates the diagnosis in the flow dynamical process. This article proposes an improvement in the basis functions introduced by Azzi et al., through the use of quadratic B-splines functions. The use of B-splines functions makes possible a smoother surface reconstruction of the density distribution, since the functions are continuous and smooth. This work describes how the modeling can be done. (author)

  1. Synthesis, characterization, and nanoindentation response of single crystal Fe–Cr–Ni alloys with FCC and BCC structures

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Y.Z. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Bei, H., E-mail: beih@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Gao, Y.F., E-mail: ygao7@utk.edu [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Catoor, D. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); George, E.P. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2014-08-12

    Fe-based alloys are used extensively in many structural applications including under irradiation conditions in the nuclear industry. In this study, model Fe–Cr, Fe–Ni and Fe–Cr–Ni alloys that are the basis of many structural steels were synthesized as single crystals and characterized. The compositions investigated were Fe–15Cr, Fe–30Cr, Fe–30Ni and Fe–15Cr–15Ni (at%). Several key mechanical properties were determined which will be useful in further studies of irradiation/deformation-induced defects. Incipient plasticity and slip characteristics were investigated by nanoindentation on (001) and (1{sup ¯}10) surfaces, and hardness, modulus, pop-in behavior and theoretical strength were determined. The slip trace patterns after microindentation were imaged in a microscope. A novel slip trace analysis was developed and the underlying deformation mechanisms identified. The analysis shows that under both (001) and (1{sup ¯}10) indentations, the activated slip system for the BCC alloys is {112}〈111〉; for the FCC alloys the activated slip plane is {111}. These results were confirmed with finite element simulations using a slip-based crystal-plasticity model. Finally, the effects of heterogeneous pop-in mechanisms are discussed in the context of incipient plasticity in the four different alloys.

  2. Metal-organic pathways for anisotropic growth of a highly symmetrical crystal structure: example of the fcc Ni.

    Science.gov (United States)

    Mourdikoudis, Stefanos; Collière, Vincent; Amiens, Catherine; Fau, Pierre; Kahn, Myrtil L

    2013-11-05

    The control of the metallic nanocrystal shape is of prime importance for a wide variety of applications. We report a detailed research work on metal-organic chemical routes for the synthesis of a highly symmetrical crystal structure. In particular, this study shows the key parameters ensuring the anisotropic growth of nickel nanostructures (fcc crystal). Numerous reaction conditions are investigated (precursors, solvents, temperature, reducing agents, reaction time, and types and ratios of surfactants, such as alkyl amines, carboxylic acids, and phosphine oxides), and their effects on the size and shape of the final product are reported. The role of the growth modifiers and the structuring of the reaction media on the anisotropic growth are demonstrated. This metal-organic approach generates several novel anisotropic nanostructures in a wide size range depending on the reaction conditions. In this way, nanomaterials with reproducible size, shape, and composition are obtained with good yield. Transmission electron microscopy techniques (TEM and HRTEM) are the principal methods for monitoring the morphology.

  3. Elastic constants of random solid solutions by SQS and CPA approaches: the case of fcc Ti-Al.

    Science.gov (United States)

    Tian, Li-Yun; Hu, Qing-Miao; Yang, Rui; Zhao, Jijun; Johansson, Börje; Vitos, Levente

    2015-08-12

    Special quasi-random structure (SQS) and coherent potential approximation (CPA) are techniques widely employed in the first-principles calculations of random alloys. Here we scrutinize these approaches by focusing on the local lattice distortion (LLD) and the crystal symmetry effects. We compare the elastic parameters obtained from SQS and CPA calculations, taking the random face-centered cubic (fcc) Ti(1-x)Al(x) (0 ≤ x ≤ 1) alloy as an example of systems with components showing different electronic structures and bonding characteristics. For the CPA and SQS calculations, we employ the Exact Muffin-Tin Orbitals (EMTO) method and the pseudopotential method as implemented in the Vienna Ab initio Simulation Package (VASP), respectively. We show that the predicted trends of the VASP-SQS and EMTO-CPA parameters against composition are in good agreement with each other. The energy associated with the LLD increases with x up to x = 0.625 ~ 0.750 and drops drastically thereafter. The influence of the LLD on the lattice constants and C12 elastic constant is negligible. C11 and C44 decrease after atomic relaxation for alloys with large LLD, however, the trends of C11 and C44 are not significantly affected. In general, the uncertainties in the elastic parameters associated with the symmetry lowering turn out to be superior to the differences between the two techniques including the effect of LLD.

  4. Synthesis and the Structural Transformation of fcc to hcp in Ni-Graphene Nanocomposite by Simple Chemical Route via Sonication

    Directory of Open Access Journals (Sweden)

    N. K. Mahale

    2014-01-01

    Full Text Available We report the synthesis and structural transformation of fcc to hcp in Ni-graphene (Ni-Gr composite by simple chemical route via sonication. The syntheses of Ni-Gr composite by simultaneous reduction method, and the effect of different composition ratio on morphology and crystal structure were examined in our present study. The results indicated that the graphene ratio played an important role in crystal structure and d-spacing in nickel crystals. Different compositions have shown different behavior. The nanonickel clusters of various shapes with coated graphene and decorated as nickel on graphene sheets are observed. The synthesized composites were characterized using X-ray diffraction (XRD, field emission scanning electron microscopy (FE-SEM, and transmission electron microscope (TEM. The XRD patterns indicated crystal lattice modifications in some composites while composites with a higher graphene ratio produced very small crystals with uniform lattice parameter and d-spacing. FE-SEM images indicated the growth of Datura fruit like shapes of nickel clusters in higher composition of nickel while the composites with least concentration of nickel were composed of cubical nanoparticles grown on graphene sheets. TEM analysis revealed many Ni nanoparticles surrounding the smooth petals like surface of graphene, with average diameters of spiky nickel nanoparticles being about 50 nm and 124 nm, respectively, on 200 nm of scale.

  5. Size effect for phase stability on Au–Cd–Ag of phase boundary composition

    Energy Technology Data Exchange (ETDEWEB)

    Matsuoka, Yuki, E-mail: matsuoka@cc.nara-wu.ac.jp [Department of Physics, Faculty of Science, Nara Women' s University, Kitauoyanishi-machi, Nara 630-8506 (Japan); Graduated School of Engineering, Osaka University (Japan); Suzuki, Keiko; Kudo, Natsuko [Department of Physics, Faculty of Science, Nara Women' s University, Kitauoyanishi-machi, Nara 630-8506 (Japan); Graduated School of Engineering, Osaka University (Japan)

    2013-11-15

    Highlights: ► Size and heat treatment effects of phase boundary composition Au{sub 52.5−x}Cd{sub 47.5}Ag{sub x} were studied. ► The transformation temperature T{sub 0} increases by quench. It is investigated that disordering of atoms and lattice defects make β-phase unstable. ► Downsizing sample decreased T{sub 0} in β-phase, showed a tendency of increase in coexistent phase. ► Downsizing is supposed to make difficult nucleation for martensitic transformation. ► Increasing of surface ratio by downsizing of powder sample is estimated to make easy to transform from unstable β-phase to martensite phase. -- Abstract: Size and heat treatment effects on martensitic transformation of phase boundary composition Au{sub 52.5−x}Cd{sub 47.5}Ag{sub x} were studied. Au{sub 52.5−x}Cd{sub 47.5}Ag{sub x} has coexistent phase of β-phase and α-phase of fcc structure at x > 42 at.%. The transformation temperature T{sub 0} decreases as Au is substituted on Ag over phase boundary. T{sub 0} increases by quench in both case of bulk and powder. This behavior is investigated that disordering of atoms and lattice defects make β-phase (L2{sub 1}, B2 or bcc) unstable. Size effect was also inspected. Downsizing sample decreased the transformation temperature in β-phase. On the contrary, the transformation temperature of the coexistent phase showed a tendency of increase. Downsizing is supposed to make difficult nucleation for martensitic transformation because of reduction of β-phase ordered volume. Increasing of surface (disorder structure) ratio by downsizing of powder sample is estimated to make easy to transform from unstable β-phase to martensite phase.

  6. Phases and Phase Transitions

    Science.gov (United States)

    Gitterman, Moshe

    2014-09-01

    In discussing phase transitions, the first thing that we have to do is to define a phase. This is a concept from thermodynamics and statistical mechanics, where a phase is defined as a homogeneous system. As a simple example, let us consider instant coffee. This consists of coffee powder dissolved in water, and after stirring it we have a homogeneous mixture, i.e., a single phase. If we add to a cup of coffee a spoonful of sugar and stir it well, we still have a single phase -- sweet coffee. However, if we add ten spoonfuls of sugar, then the contents of the cup will no longer be homogeneous, but rather a mixture of two homogeneous systems or phases, sweet liquid coffee on top and coffee-flavored wet sugar at the bottom...

  7. Localized surface plasmon behavior of Ag-Cu alloy nanoparticles stabilized by rice-starch and gelatin

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Manish Kumar; Mandal, R. K., E-mail: rkmandal.met@itbhu.ac.in [Department of Metallurgical Engineering, IIT (BHU), Varanasi and DST Unit on Nanoscience and Technology, BHU, Varanasi-221 005 (India); Manda, Premkumar; Singh, A. K. [DefenceMetallurgical Research Laboratory, KanchanBagh, Hyderabad-500058 (India)

    2015-10-15

    The purpose of this communication was to understand localized surface plasmon behavior of a series of Ag-Cu alloy nanoparticles capped by rice-starch and gelatin. The structures of dried powders were investigated with the help of X-ray diffraction. The analysis revealed Ag-rich and Cu-rich phases with maximum solid solubility of Cu ∼9 atom per cent; 8 atom per cent and Ag ∼ 16 atom per cent; 14 atom per cent in rice-starch and gelatin capped samples respectively. Transmission electron microscope was used for knowing the particle size as well as to supplement FCC phase formations of Ag-rich and Cu-rich solid phases arrived at based on X-ray diffraction studies. The UV-Vis spectra of sols were examined for the formation and stability of alloy nanoparticles. The temporal evolution of LSPR curves gave us to assert that the sol is stable for more than two months. Small angle X-ray scattering in the sol state was extensively utilized to understand nature of suspensions in terms of fractals. Such a study is important for having a correlation between LSPR behaviors with those of nanoparticle dispersion in aqueous media. It is believed that this work will be a contribution to the emerging field of plasmonics that include applications in the area of photophysical processes and photochemical reactions.

  8. Microstructure refinement and hardening of Ag–20 wt.%Cu alloy by rapid solidification

    Energy Technology Data Exchange (ETDEWEB)

    Lussana, Danilo, E-mail: danilo.lussana@unito.it [Dipartimento di Chimica and NIS, Università di Torino, Torino (Italy); Castellero, Alberto [Dipartimento di Chimica and NIS, Università di Torino, Torino (Italy); Vedani, Maurizio [Dipartimento di Meccanica, Politecnico di Milano, Milano (Italy); Ripamonti, Dario; Angella, Giuliano [Istituto IENI-CNR, Unità territoriale di Milano, Milano (Italy); Baricco, Marcello [Dipartimento di Chimica and NIS, Università di Torino, Torino (Italy)

    2014-12-05

    Highlights: • Ag80–Cu20 alloy were rapidly solidified by planar flow casting technique. • A significant refinement of the eutectic microstructure has been obtained. • A refinement of the primary silver-rich phase has been achieved with high cooling rate. • The hardness increases up to the 150% of the value of an annealed sample. - Abstract: Ag–20 wt.%Cu (wt%) hypoeutectic alloy has been rapidly solidified by means of planar flow casting technique. Two fcc solid solutions have been identified by X-ray diffraction. Microstructures have been observed by electron microscopy. A refinement of the eutectic microstructure, as well as of the Ag-rich primary phase, has been observed for high quenching rates, leading to a hardness value up to 235 Vickers. The lattice parameter and phase fraction of the Ag-rich solid solution increase as a function of quenching rates (i.e. wheel speed). The solidification processes occurring during rapid quenching have been described on the basis of thermodynamic and kinetic arguments.

  9. New FCC Mg–Zr and Mg–Zr–ti deuterides obtained by reactive milling

    Energy Technology Data Exchange (ETDEWEB)

    Guzik, Matylda N., E-mail: matylda.guzik@ife.no; Deledda, Stefano; Sørby, Magnus H.; Yartys, Volodymyr A.; Hauback, Bjørn C.

    2015-03-15

    Results for binary Mg–Zr and ternary Mg–Zr–Ti mixtures ball milled at room temperature under reactive deuterium atmosphere (5.6–6.7 MPa) are reported. X-ray and neutron powder diffraction combined with Rietveld refinements show that two new cubic phases were formed during milling. Mg{sub 0.40}Zr{sub 0.60}D{sub 1.78} and Mg{sub 0.40}Zr{sub 0.26}Ti{sub 0.34}D{sub 1.98} crystallize with disordered face centered cubic metal atom arrangements. Results of differential scanning calorimetry and termogravimetric measurements demonstrate that both deuterides desorb deuterium at lower temperatures than MgD{sub 2}, ZrD{sub 2} or TiD{sub 2}; 528 and 575 K in the Mg–Zr–D and Mg–Zr–Ti–D system, respectively. Interestingly, Mg{sub 0.40}Zr{sub 0.26}Ti{sub 0.34}D{sub 1.98} stores deuterium reversibly at 673 K and 10 MPa of D{sub 2}. - Graphical abstract: High resolution SR-PXD patterns obtained for Mg{sub 0.40}Zr{sub 0.60}D{sub 1.78} and first time reported Mg{sub 0.40}Zr{sub 0.26}Ti{sub 0.34}D{sub 1.98}. - Highlights: • Synthesis and characterization of Mg{sub 0.40}Zr{sub 0.60}D{sub 1.78} and Mg{sub 0.40}Zr{sub 0.26}Ti{sub 0.34}D{sub 1.98}. • New deuterides obtained by milling under H{sub 2} gas pressure in the order of a few MPa. • Phases desorb deuterium at temperature lower than corresponding binary deuterides. • Mg{sub 0.40}Zr{sub 0.26}Ti{sub 0.34}D{sub 1.98} stores hydrogen reversibly at 673 K and 10 MPa of D{sub 2}.

  10. Full mass dependence in Higgs boson production in association with jets at the LHC and FCC

    CERN Document Server

    Greiner, Nicolas; Luisoni, Gionata; Schönherr, Marek; Winter, Jan-Christopher

    2017-01-01

    The first computation of Higgs production in association with three jets at NLO in QCD has recently been performed using the effective theory, where the top quark is treated as an infinitely heavy particle and integrated out. This approach is restricted to the regions in phase space where the typical scales are not larger than the top quark mass. Here we investigate this statement at a quantitative level by calculating the leading-order contributions to the production of a Standard Model Higgs boson in association with up to three jets taking full top-quark and bottom-quark mass dependence into account. We find that the transverse momentum of the hardest particle or jet plays a key role in the breakdown of the effective theory predictions, and that discrepancies can easily reach an order of magnitude for transverse momenta of about 1 TeV. The impact of bottom-quark loops are found to be visible in the small transverse momentum region, leading to corrections of up to 5 percent. We further study the impact of m...

  11. Nucleation barrier of fcc(γ)→hcp(ε) martensitic transformation in Fe-based alloys

    Institute of Scientific and Technical Information of China (English)

    HUANG Xing; CHEN Shipu

    2004-01-01

    Based on the dislocation theory and Olson's stacking fault model, a model describing the nucleation of an hcp(ε) martensite embryo at low-angle grain boundary is proposed with the influence of external stress field taken into account. The dependences of temperature (T), shear stress (τ) and dislocation density at grain boundary on the martensite nucleation in FeMnSi based alloy, as an example, are numerically simulated. It has been shown that there exist the subcritical and critical embryos during the course of ε-phase nucleation. The free energy difference between them is just the energy barrier of embryo growth. Depending on T and τ, the characteristic embryo sizes may vary in wide ranges and decrease with increasing σ and decreasing T. The energy condition of martensitic transformation at Ms and critical shear stress (τc) is discussed from the viewpoint of kinetics and thus the TEM observed result that stacking fault energy is not zero at Ms temperature is reasonably explained. Besides, it is predicted that the high dislocation density at grain boundary can promote the nucleation of fcc→hcp transformation in Fe-based alloys.

  12. Magnetic states, correlation effects and metal-insulator transition in FCC lattice

    Science.gov (United States)

    Timirgazin, M. A.; Igoshev, P. A.; Arzhnikov, A. K.; Irkhin, V. Yu

    2016-12-01

    The ground-state magnetic phase diagram (including collinear and spiral states) of the single-band Hubbard model for the face-centered cubic lattice and related metal-insulator transition (MIT) are investigated within the slave-boson approach by Kotliar and Ruckenstein. The correlation-induced electron spectrum narrowing and a comparison with a generalized Hartree-Fock approximation allow one to estimate the strength of correlation effects. This, as well as the MIT scenario, depends dramatically on the ratio of the next-nearest and nearest electron hopping integrals {{t}\\prime}/t . In contrast with metallic state, possessing substantial band narrowing, insulator one is only weakly correlated. The magnetic (Slater) scenario of MIT is found to be superior over the Mott one. Unlike simple and body-centered cubic lattices, MIT is the first order transition (discontinuous) for most {{t}\\prime}/t . The insulator state is type-II or type-III antiferromagnet, and the metallic state is spin-spiral, collinear antiferromagnet or paramagnet depending on {{t}\\prime}/t . The picture of magnetic ordering is compared with that in the standard localized-electron (Heisenberg) model.

  13. Full mass dependence in Higgs boson production in association with jets at the LHC and FCC

    CERN Document Server

    Greiner, Nicolas; Luisoni, Gionata; Schonherr, Marek; Winter, Jan-Christopher

    2016-01-01

    The first computation of Higgs production in association with three jets at NLO in QCD has recently been performed using the effective theory, where the top quark is treated as an infinitely heavy particle and integrated out. This approach is restricted to the regions in phase space where the typical scales are not larger than the top quark mass. Here we investigate this statement at a quantitative level by calculating the leading-order contributions to the production of a Standard Model Higgs boson in association with up to three jets taking full top-quark and bottom-quark mass dependence into account. We find that the transverse momentum of the hardest particle or jet plays a key role in the breakdown of the effective theory predictions, and that discrepancies can easily reach an order of magnitude for transverse momenta of about 1 TeV. The impact of bottom-quark loops are found to be visible in the small transverse momentum region, leading to corrections of up to 5 percent. We further study the impact of m...

  14. Glassy and icosahedral phases in rapidly solidified Ti-Zr-Hf-(Fe, Co orNi) alloys

    OpenAIRE

    Chen, N.; Louzguine-Luzgin, DV; Ranganathan, S; Inoue, A.

    2005-01-01

    The icosahedral quasicrystalline, amorphous plus crystalline and glassy phases were formed in $Ti_{40}Zr_{20}Hf_{20}(3d-LTM)_{20}$ alloys (3d-LTM = 3d late transition metals Fe, Co and Ni). The icosahedral phase formed in the melt-spun $Ti_{40}Zr_{20}Hf_{20}Fe_{20}$ alloy is metastable and the average size ofthe quasicrystalline icosahedral particles precipitated in the amorphous matrix is 5 nm. The metastable icosahedral phase transformed to a big-cubic fcc $Hf_{2}Fe$ phase with the grain si...

  15. Numerical Modeling of Reactive Multiphase Flow for FCC and Hot Gas Desulfurization Circulating Fluidized Beds

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Aubrey L. [WSU Research Corporation, Morgantown, WV (USA)

    2005-07-01

    This work was carried out to understand the behavior of the solid and gas phases in a CFB riser. Only the riser is modeled as a straight pipe. A model with linear algebraic approximation to solids viscosity of the form, {musubs} = 5.34{epsisubs}, ({espisubs} is the solids volume fraction) with an appropriate boundary condition at the wall obtained by approximate momentum balance solution at the wall to acount for the solids recirculation is tested against experimental results. The work done was to predict the flow patterns in the CFB risers from available experimental data, including data from a 7.5-cm-ID CFB riser at the Illinois Institute of Technology and data from a 20.0-cm-ID CFB riser at the Particulate Solid Research, Inc., facility. This research aims at modeling the removal of hydrogen sulfide from hot coal gas using zinc oxide as the sorbent in a circulating fluidized bed and in the process indentifying the parameters that affect the performance of the sulfidation reactor. Two different gas-solid reaction models, the unreacted shrinking core (USC) and the grain model were applied to take into account chemical reaction resistances. Also two different approaches were used to affect the hydrodynamics of the process streams. The first model takes into account the effect of micro-scale particle clustering by adjusting the gas-particle drag law and the second one assumes a turbulent core with pseudo-steady state boundary condition at the wall. A comparison is made with experimental results.

  16. Microscopic dynamics of AC{sub 60} compounds in the plastic, polymer, and dimer phases investigated by inelastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Schober, H.; Toelle, A. [Institut Laue-Langevin, F-38042 Grenoble (France); Renker, B.; Heid, R.; Gompf, F. [INFP, Forschungszentrum Karlsruhe, D-76021 Karlsruhe (Federal Republic of Germany)

    1997-09-01

    We present inelastic neutron-scattering results for AC{sub 60} (A=K,Rb,Cs) compounds. The spectra of the high-temperature fcc phases strongly resemble the ones of pristine C{sub 60} in the plastic phase. At equal temperatures we find identical rotational diffusion constants for pristine C{sub 60} and Rb{sub 1}C{sub 60} (D{sub r}=2.4 10{sup 10} s{sup {minus}1} at 400 K). The changes taking place in the inelastic part of the spectra on cooling AC{sub 60} indicate the formation of strong intermolecular bonds. The buildup of intensities in the gap region separating internal and external vibrations in pure C{sub 60} is the most prominent signature of this transition. The spectra of the low-temperature phases depend on their thermal history. The differences can be explained by the formation of a polymer phase (upon slow cooling from the fcc phase) and a dimer phase (upon fast cooling), respectively. The experimental data are analyzed on the basis of lattice dynamical calculations. The density-of-states are well modeled assuming a [2+2] bond for the polymer and a single intercage bond for the dimer. Indications for different intercage bonding are also found in the internal mode spectra, which, on the other hand, react only weakly to the charge transfer. The dimer phase is metastable and converts into the polymer phase with a strongly temperature-dependent time constant. The transition from the polymer to the fcc phase is accompanied by inelastic precursor effects which are interpreted as the signature of inhomogeneities arising from plastic monomer regions embedded in the polymer phase. In the polymer phase AC{sub 60} compounds show strong anharmonic behavior in the low-temperature region. The possible connection with the metal-to-insulator transition is discussed. {copyright} {ital 1997} {ital The American Physical Society}

  17. In-situ Phase Transformation and Deformation of Iron at High Pressure andTemperature

    Energy Technology Data Exchange (ETDEWEB)

    Miyagi, Lowell; Kunz, Martin; Knight, Jason; Nasiatka, James; Voltolini, Marco; Wenk, Hans-Rudolf

    2008-07-01

    With a membrane based mechanism to allow for pressure change of a sample in aradial diffraction diamond anvil cell (rDAC) and simultaneous infra-red laser heating, itis now possible to investigate texture changes during deformation and phasetransformations over a wide range of temperature-pressure conditions. The device isused to study bcc (alpha), fcc (gamma) and hcp (epislon) iron. In bcc iron, room temperature compression generates a texture characterized by (100) and (111) poles parallel to the compression direction. During the deformation induced phase transformation to hcp iron, a subset of orientations are favored to transform to the hcp structure first and generate a texture of (01-10) at high angles to the compression direction. Upon further deformation, the remaining grains transform, resulting in a texture that obeys the Burgers relationship of (110)bcc // (0001)hcp. This is in contrast to high temperature results that indicate that texture is developed through dominant pyramidal {2-1-12}<2-1-13> and basal (0001)-{2-1-10} slip based on polycrystal plasticity modeling. We also observe that the high temperature fcc phase develops a 110 texture typical for fcc metals deformed in compression.

  18. Microkinetic interpretation of HDS/HYDO selectivity of the transformation of a model FCC gasoline over transition metal sulfides

    Energy Technology Data Exchange (ETDEWEB)

    Daudin, A. [UMR CNRS 6503, Catalyse en Chimie Organique, Universite de Poitiers, Faculte des Sciences Fondamentales et Appliquees, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex (France); IFP-Lyon, Direction Catalyse et Separation, BP 3, 69390 Vernaison (France); Lamic, A.F.; Perot, G.; Brunet, S. [UMR CNRS 6503, Catalyse en Chimie Organique, Universite de Poitiers, Faculte des Sciences Fondamentales et Appliquees, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex (France); Raybaud, P. [IFP, Direction Chimie et Physico-Chimie Appliquees, 1-4 Av. de Bois Preau, 92858 Rueil Malmaison (France); IFP-Lyon, Direction Catalyse et Separation, BP 3, 69390 Vernaison (France); Bouchy, C. [IFP-Lyon, Direction Catalyse et Separation, BP 3, 69390 Vernaison (France)

    2008-01-15

    The conversion of a model FCC gasoline (composed of 2-methylthiophene (2MT), 2,3-dimethylbut-2-ene (23DMDB2N) and orthoxylene in n-heptane) under realistic hydrodesulfurization (HDS) conditions was investigated over a series of transition monometallic sulfides (Ni{sub 3}S{sub 2}, PdS, Co{sub 9}S{sub 8}, Rh{sub 2}S{sub 3}, RuS{sub 2}, PtS and MoS{sub 2}) and unsupported transition bimetallic sulfide catalysts (NiMoS and CoMoS). The results reveal for the first time that a volcano curve relationship exists between the ab initio calculated sulfur-metal bond energy, E(MS), descriptor of bulk TMS and their activities in olefin hydrogenation and in alkylthiophene desulfurization measured simultaneously. In particular, Rh{sub 2}S{sub 3} with an intermediate sulfur-metal bond energy of 119 kJ/mol is the most active catalyst in both case hydrogenation of the olefin and in HDS of a sulfur compound. Furthermore, the HDS/HYDO selectivity which is the most important parameter in the deep HDS of gasoline, presents a maximum for the NiMoS catalyst with E(MS) of 128 kJ/mol. A microkinetic model based on Broensted-Evans-Polanyi relationships and the competitive adsorption of the sulfur molecule and alkene on the catalytic site is proposed to give a rational interpretation of the experimental catalytic results. (author)

  19. Means And Ends In City Of Arlington v. FCC: Ignoring The Lawyer's Craft to Reshape the Scope of Chevron Deference

    Directory of Open Access Journals (Sweden)

    Michael P. Healy

    2015-07-01

    Full Text Available In last year’s term, the United States Supreme Court considered the question of the scope of Chevron deference in City of Arlington v. FCC. This article discusses how the decision is an example of the work of an activist Court. The case should have been resolved by a straight forward determination under the analysis of United States v. Mead that Chevron deference simply did not apply to the Federal Communications Commission’s (“FCC” legal determination. The Court ignored this restrained approach to the case and instead addressed the question the Justices desired to decide: the reach of Chevron deference. The article discusses and criticizes the approach of Justice Scalia writing for the majority and of Chief Justice Roberts writing for three dissenting Justices.Practitioners and scholars of administrative law can only be confused by the Court’s willingness to apply Chevron in City of Arlington, given the informal administrative action being reviewed and the fact that neither reviewing court actually applied each of the two parts of the Mead test. The Court’s flawed administrative law analysis results from the activist concerns of Justice Scalia and Chief Justice Roberts. Justice Scalia uses the case as a vehicle to undermine Mead, a decision that Justice Scalia loathes. Chief Justice Roberts uses the case as a vehicle to advocate for less judicial deference and less law defining power for increasingly powerful agencies. Neither member of the Court allowed the applicable rules of contemporary administrative law to hinder his efforts to achieve his broader goals. Administrative law would have been better served if a properly restrained Court had considered and applied the previously determined rules for judicial review of administrative agencies. 

  20. Microstructural Characterization of Dislocation Networks During Harper-Dorn Creep of fcc, bcc, and hcp Metals and Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Przystupa, Marek A.

    2007-12-13

    Harper-Dorn (H-D) creep is observed in metals and geological materials exposed to very low stresses at temperatures close to the melting point. It is one of several types of creep processes wherein the steady-state strain rate is proportional to the applied stress, Nabarro-Herring creep and Coble creep being two other important processes. H-D creep can be somewhat insidious because the creep rates are much larger than those expected for Nabarro-Herring or Coble creep. Since the working conditions of structural components of power plants and propulsion systems, as well as the motion of the earth’s mantle all involve very low stresses, an understanding of the factors controlling H-D creep is critical in preventing failures associated with those higher-than-expected creep rates. The purpose of this investigation was to obtain missing microstructural information on the evolution of the dislocation structures during static annealing of materials with fcc, bcc and hcp structure and use obtained results to test predictive capabilities of the dislocation network theory of H-D creep. In our view the evolutionary processes during static annealing and during Harper-Dorn creep are intimately related. The materials used in this study were fcc aluminum, hcp zinc and bcc tin. All characterizations of dislocation structures, densities and dislocation link length distributions were carried out using the etch pit method. To obtain quantitative information on the evolution of the dislocation networks during annealing the pure fcc aluminum samples were pre-deformed by creep at 913 and 620 K and then annealed. The higher deformation temperature was selected to generate starting dislocation networks similar to those forming during Harper-Dorn creep and the lower, to obtain higher dislocation densities suitable for reliable estimates of the parameters of the network growth law. The measured experimental link length distribution were, after scaling, (1) the same for all annealing