WorldWideScience

Sample records for a-ga010 studiedby spa-leed

  1. A combined STM and SPA-LEED study of the "explosive" nucleation and collective diffusion in Pb/Si(111)

    Science.gov (United States)

    Hattab, H.; Hupalo, M.; Hershberger, M. T.; Horn von Hoegen, M.; Tringides, M. C.

    2016-04-01

    A novel type of very fast nucleation was recently found in Pb/Si(111) with 4- to 7-layer high islands becoming crystalline in an "explosive" way, when the Pb deposited amount in the wetting layer is compressed to θc ~ 1.22 ML, well above the metallic Pb(111) density. This "explosive" nucleation is very different from classical nucleation when island growth is more gradual and islands grow in size by single adatom aggregation [8]. In order to identify the key parameters that control the nucleation we used scanning tunneling microscopy (STM) and spot profile analysis low energy electron diffraction (SPA-LEED). It was found that the number and duration of steps in iterative deposition used to approach θc and the flux rate have dramatic effects on the crystallization process. Larger depositions over shorter times induce greater spatial coverage fluctuations, so local areas can reach the critical coverage θc easier. This can trigger the collective motion of the wetting layer from far away to build the Pb islands "explosively". The SPA-LEED experiments show that even low flux experiments in iterative deposition experiments can trigger transfer of material to the superstable 7-layer islands, as seen from the stronger satellite rings close to the (00) spot.

  2. Growth of NaCl on thin epitaxial KCl films on Ag(100) studied by SPA-LEED

    Science.gov (United States)

    Marquardt, Christian; Paulheim, Alexander; Sokolowski, Moritz

    2015-11-01

    We investigated the growth of NaCl on thin (100)-oriented films of KCl by spot profile analysis of low energy electron diffraction (SPA-LEED). The underlying question of this investigation was how the system accommodates to the misfit of - 10% between the NaCl and KCl lattices. The KCl films (3 atomic layers thick) were epitaxially grown on a Ag(100) single crystal. We studied the heteroepitaxial growth of NaCl on KCl at 300 K and at 500 K, respectively. At 300 K, the first NaCl monolayer (ML) grows pseudomorphically on the KCl film. From the second layer onward, the NaCl lattice relaxes. The NaCl multilayers roughen, and a small rotational disorder (± 4°) of the NaCl domains is observed. The roughening results from the formation of multilayer islands of limited lateral size due to the misfit to the pseudomorphic first NaCl layer. At a growth temperature of 500 K, no pseudomorphic NaCl layer forms, instead relaxed multilayer island growth of NaCl is observed from the first layer onward. Similarly to the growth at 300 K, we find NaCl multilayer islands of limited lateral size. For both temperatures, we explain this growth behavior by the misfit that makes the adsorption sites at the island edges of the first relaxed NaCl layer less favorable for larger islands, promoting nucleation of multilayer islands.

  3. Probing the buried Pb/Si(111) interface with SPA LEED and STM on Si(111)-Pbα√3×√3.

    Science.gov (United States)

    Yakes, M; Tringides, M C

    2011-06-30

    High resolution spot profile analysis low energy electron diffraction (SPA-LEED) and variable temperature scanning tunneling microscopy (STM) have been used to observe the growth of Pb on the Pb/Si(111)-α√3×√3 phase, which is driven by quantum size effects (QSE). A change in the rotation of the Pb grown islands with respect to the Si substrate has been observed with increasing coverage θ. At lower coverage, separated two-step islands are grown and are aligned with the [110] axis of the substrate. With increasing coverage above 1.5 ML, of the islands coalesce and form a bilayer, with additional islands grown on top. The preferred Pb island orientation changes to 5.6° with respect to the [110] direction. These changes at the metal/semiconductor buried interface are obtained both with SPA LEED and STM as changes to the period of the Moire pattern. The method of analysis of the corrugation period and rotation angle of the Moire pattern measured with diffraction and STM can be applied to obtain the structure of buried metal/substrate interfaces in other epitaxial systems.

  4. SPA-LEED study of the morphology and nucleation of a novel growth mode and the "devil's staircase" on lead/silicon(111)

    Science.gov (United States)

    Yeh, Wang-Chi Vincent

    In this thesis we describe two intriguing and unexpected discoveries we made in the Pb/Si(111). A novel growth mode was discovered on Pb thin film grown on Si(111)-7 x 7 reconstructed surface: nano-scale islands of uniform 7-layer height with steep edges and flat tops can form below room temperature. This growth mode is different from the three common modes: Frank-van der Merwe, Volmer-Weber, and Stranski-Krastanov modes. The three common modes could be explained by thermodynamic considerations on the surface free energy and do not lead to the type of self-organization we have discovered. This novel mode is explained by quantum size effects (QSE), which states that the confinement of electrons inside a well requires that the dimensions of the well meet the requirements of energy quantization: the electron wavefunctions have to form standing waves within the confining well. Further study showed that different stable heights that differ by two-layer difference could be selected by changing deposition temperature, total coverage, annealing temperature, or initial interface. Oxygen covered structures are found to retain their selected height up to almost room temperature. In addition, a novel "devil's staircase" was discovered in Pb/Si(111) between coverage 6/5 ML and 4/3 ML. Experimentally it has been an outstanding challenge to show a "devil's staircase" since physical phenomena are not expected to be described by non-differentiable functions, i.e., the stability curve Deltamu vs. theta of a "devil's staircase". This novel staircase differs from conventional ones in the difference between their two generating phases: their [11¯0] dimensions differ by two lattice constants instead of one. It was found unexpectedly that such a staircase can form with macroscopic spatial extent (˜0.5 mm) even at low temperature (T ˜ 120K) where atoms are not expected to mobile! This unusual result suggests that a high degree of self-organization is possible in the system of Pb/Si(111).

  5. Reactivity of Au nanoparticles supported over SiO2 and TiO2 studiedby ambient pressure photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Herranz, Tirma; Deng, Xingyi; Cabot, Andreu; Alivisatos, Paul; Liu, Zhi; Soler-Illia, Galo; Salmeron, Miquel

    2009-04-15

    The influence of the metal cluster size and the identity of the support on the reactivity of gold based catalysts have been studied in the CO oxidation reaction. To overcome the structural complexity of the supported catalysts, gold nanoparticles synthesized from colloidal chemistry with precisely controlled size have been used. Those particles were supported over SiO{sub 2} and TiO{sub 2} and their catalytic activity was measured in a flow reactor. The reaction rate was dependent on the particle size and the support, suggesting two reaction pathways in the CO oxidation reaction. In parallel, ambient pressure photoelectron spectroscopy (APPS) has been performed under reaction conditions using bidimensional model catalysts prepared upon supporting the Au nanoparticles over planar polycrystalline SiO{sub 2} and TiO{sub 2} thin films by means of the Langmuir-Blodgett (LB) technique to mimic the characteristic of the powder samples. In this way, the catalytically active surface was characterized under true reaction conditions, revealing that during CO oxidation gold remains in the metallic state.

  6. Isotropic thin PTCDA films on GaN(0 0 0 1)

    Science.gov (United States)

    Ahrens, Ch; Flege, J. I.; Jaye, C.; Fischer, D. A.; Schmidt, Th; Falta, J.

    2016-11-01

    The growth of 3, 4, 9, 10-perylene tetracarboxylic dianhydride (PTCDA) on the Ga-polar GaN(0 0 0 1) surface has been studied by x-ray photoelectron spectroscopy (XPS), spot profile analysis low-energy electron diffraction (SPA-LEED), near edge x-ray absorption fine structure (NEXAFS), and scanning tunneling microscopy (STM). The stoichiometric ratios derived from XPS indicate that the molecules remain intact upon adsorption on the surface. Furthermore, no chemical shifts can be observed in the C 1s and O 1s core levels with progressing deposition of PTCDA, suggesting none or only weak interactions between the molecules and the substrate. NEXAFS data indicate the PTCDA molecules being oriented with their molecular plane parallel to the surface. High-resolution STM shows PTCDA islands of irregular shape on the sub-micron scale, and together with corresponding SPA-LEED data reveals a lateral ordering of the molecules that is compatible with the presence of (1 0 2) oriented PTCDA nano-crystals. SPA-LEED moreover clearly shows the presence of homogeneously distributed rotational domains of two-dimensionally isotropic PTCDA.

  7. Structure and morphology of the tenfold surface of decagonal Al71.8 Ni14.8 Co13.4 in its low-temperature random tiling type-I modification

    Science.gov (United States)

    Sharma, H. R.; Franke, K. J.; Theis, W.; Riemann, A.; Fölsch, S.; Gille, P.; Rieder, K. H.

    2004-12-01

    We have investigated the structure and morphology of the tenfold surface of decagonal Al71.8Ni14.8Co13.4 by highly surface sensitive He atom scattering (HAS), high resolution low energy electron diffraction(SPA-LEED), and low temperature scanning tunneling microscopy (STM). The SPA-LEED patterns reveal more than 500 individual diffraction spots in the k -vector range of ∣k‖∣Fibonacci sequence, this is linked to the random nature of the tiling of the type-I structure. STM measurements reveal a surface morphology characterized by rough single-height steps separating terraces with widths on the order of 100Å . Two different surface terminations are observed, a coarse and a fine one, frequently coexisting on single terraces. The fine structure termination directly reflects the atomic structure of a bulk truncated surface, allowing a random rhombic tiling to be identified. In order to compare diffraction, real-space data, and atomic structure models, the Patterson function and autocorrelation of the surface structure, respectively, are studied. This allows an understanding of the coarse structure termination as consisting of subunits of a few atoms each arranged statistically on sites defined by the atomic tiling of the bulk tenfold planes.

  8. Controlling atomistic processes on Pb films via quantum size effects and lattice rotation

    Energy Technology Data Exchange (ETDEWEB)

    Binz, Steven [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    The two main techniques used to record the data in this dissertation were Spot Profile Analysis - Low Energy Electron Diffraction (SPA-LEED) and Scanning Tunneling Microscopy (STM). A specific data analysis technique for LEED data called G(S) curves is described in depth. G(S) curves can provide a great deal of structural information about the surface; including step heights, island size, and island separation. The effects of quantum size effects (QSE) on the diffusion and critical island sizes of Pb and In on Pb films are reported. Pb depositions on the 2D In phases {radical}3 and {radical}31 to see how the phases affect the Pb growth and its strong QSE are reported.

  9. Adsorption of phthalocyanines on noble metal surfaces; Adsorption von Phthalocyaninen auf Edelmetalloberflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Kroeger, Ingo

    2011-05-20

    In this thesis the adsorbate systems CuPc/Ag(111), CuPc/Au(111), CuPc/Cu(111), H2Pc and TiOPc/Ag(111) were investigated and characterized in great detail using complementary methods. The focus of the experiments was the determination of lateral geometric structures with spot-profile-analysis low energy electron diffraction (SPA-LEED) and scanning tunneling microscopy (STM), as well as the measurement of adsorption heights using the method of normal incidence X-ray standing waves (NIXSW). High resolution electron energy loss spectroscopy (HREELS) was used to characterize the vibronic properties of the molecule and the interface dynamical charge transfer (IDCT). The electronic structure and the charge transfer into the molecule were investigated with ultraviolet photoelectron spectroscopy (UPS). The most important results of this work are related with the interplay between adsorbate-substrate and adsorbate-adsorbate interaction of Phthalocyanines in the submonolayer regime. (orig.)

  10. Surface stress and large-scale self-organization at organic-metal interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pollinger, Florian

    2009-01-22

    The role of elastic interactions, particularly for the self-organized formation of periodically faceted interfaces, was investigated in this thesis for archetype organic-metal interfaces. The cantilever bending technique was applied to study the change of surface stress upon formation of the interface between 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) and Ag(111). The main focus of this work was on the investigation of the formation of the long-range ordered, self-organized faceted PTCDA/Ag(10 8 7) interface. Reciprocal space maps of this interface were recorded both by spot profile analysis low energy electron diffraction (SPA-LEED) and low energy electron microscopy (LEEM) in selected area LEED mode. Complementary to the reciprocal data, also microscopic real-space LEEM data were used to characterize the morphology of this interface. Six different facet faces ((111), (532), (743), (954), (13 9 5), and (542)) were observed for the preparation path of molecular adsorption on the substrate kept at 550 K. Facet-sensitive dark-field LEEM localized these facets to grow in homogeneous areas of microscopic extensions. The temperature-dependence of the interface formation was studied in a range between 418 K and 612 K in order to learn more about the kinetics of the process. Additional steeper facets of 27 inclination with respect to the (111) surface were observed in the low temperature regime. Furthermore, using facet-sensitive dark-field LEEM, spatial and size distributions of specific facets were studied for the different temperatures. Moreover, the facet dimensions were statistically analyzed. The total island size of the facets follows an exponential distribution, indicating a random growth mode in absence of any mutual facet interactions. While the length distribution of the facets also follows an exponential distribution, the width distribution is peaked, reflecting the high degree of lateral order. This anisotropy is temperature-dependent and occurs

  11. Morphological transformation of the silicon(112) surface through metal adsorption. Faceting vs. stabilization; Morphologische Transformation der Silizium(112) Oberflaeche durch Metalladsorption. Facettierung vs. Stabilisierung

    Energy Technology Data Exchange (ETDEWEB)

    Wiethoff, Christian

    2010-06-21

    Semiconductor nanowires lately attracted immense attention in worldwide research. Lots of possible applications were discussed and partially realized. Gold is the most commonly used metal in catalyzed nanowire growth, but exhibits poor electronic properties for building integrated circuits. Recently, aluminium was achieved to work as a catalyst and the nanowires grown this way showed extremely smooth surfaces. This is in contrast to surfaces grown with other metals. In this work the modification of the silicon (112) surface by metal adsorption is studied. Since nanowires with [111] growth direction have [112]-like sidewalls, this way a virtually endless nanowire surface is used to study the interaction of gold, silver and aluminium with the silicon surface. Spot Profile Analysis Low Energy Electron Diffraction (SPA-LEED) is used to analyze the surfaces. This high resolution diffraction method allows for detailed characterization of the surface structures and facets. Gold adsorption leads to eight different surface phases, the most stable one exhibits 111- and 113-facets and is shown to occur on nanowire surfaces if they were grown with gold as a catalyst. Silver adsorption pushes the surface to form 111- and 115-facets. The facet size distribution is quite narrow, so the finite size effect creates intensity minima in the vicinity of the bragg points in diffraction patterns. Aluminium adsorption finally leads to a stabilization of the silicon (112) surface, no facets are formed. This atomic flat surface was seen on nanowire sidewalls, grown with aluminium as catalyst. (orig.)

  12. Switching orientation of adsorbed molecules: Reverse domino on a metal surface

    Science.gov (United States)

    Braatz, C. R.; Esat, T.; Wagner, C.; Temirov, R.; Tautz, F. S.; Jakob, P.

    2016-01-01

    A thus far unknown phase of 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA) on Ag(111), characterized by an all perpendicular orientation of the planar molecules and bound to the Ag substrate through the carboxyl oxygen atoms has been identified using infrared absorption spectroscopy and scanning tunneling microscopy. Its formation process requires second layer NTCDA to squeeze into empty spaces between relaxed monolayer NTCDA molecules. Remarkably, this process causes initially parallel oriented NTCDA to likewise adopt the new, highly inclined adsorption geometry. According to our SPA-LEED and STM findings, the new phase displays a distinct long range order and shows a pronounced tendency to form 1D rows or narrow islands. We suggest that extra NTCDA preferentially transforms into the upright configuration close to existing islands and attaches to them, i.e. the transformation process proceeds in a directed and recurrent manner (reverse domino scenario). Identical processing starting with a compressed NTCDA/Ag(111) monolayer leads to a purely parallel oriented bilayer, that is, the NTCDA monolayer phase is retained and merely acts as a passive template for bilayer NTCDA. The new vertical NTCDA phase represents an unusual molecular system with π-orbitals oriented parallel to a metal surface. A substantially reduced coupling of these orbitals to Ag(111) electronic levels is conjectured, which will have a major impact on intermolecular couplings and electronically excited state lifetimes.

  13. Coadsorption of potassium and nitrogen on the Ni(100) surface

    CERN Document Server

    Scantlebury, M J

    1998-01-01

    R-factor analysis carried out over a wide area of parameter space has yielded structural parameters as deep as the third Ni layer. Simulations of data obtained for Ni(100)-(K+N) were not attempted due to the similarity of the PD curves with those of the Ni/N system. From the point of view of PD, there are no structural differences between the pure N and the K coadsorbed systems, in contrast to the SPA-LEED and ARUPS results. A scanning tunnelling microscopy (STM) study has been performed on the Ni(100)-(K+N) system. By gradually dosing the Ni/N surface with K, it was possible to observe the K atoms initially adsorbing preferentially along [001] step edges, before forming protrusions approx 10 A in diameter on the terraces at higher coverages. The disturbance of the substrate underlying these protrusions has been imaged and suggests a local interaction of K with the surface. As the K coverage increased to 0.5 ML, the protrusions appear to coalesce. The K atoms have also been shown to be immobile on the surface...

  14. Surface reconstruction of Pt(001) quantitatively revisited

    Science.gov (United States)

    Hammer, R.; Meinel, K.; Krahn, O.; Widdra, W.

    2016-11-01

    The complex hexagonal reconstructions of the (001) surfaces of platinum and gold have been under debate for decades. Here, the structural details of the Pt(001) reconstruction have been quantitatively reinvestigated by combining the high resolving power of scanning tunneling microscopy (STM) and spot profile analysis low energy electron diffraction (SPA-LEED). In addition, LEED simulations based on a Moiré approach have been applied. Annealing temperatures around 850 °C yield a superstructure that approaches a commensurable c (26.6 ×118 ) substrate registry. It evolves from a Moiré-like buckling of a compressed hexagonal top layer (hex) where atomic rows of the hex run parallel to atomic rows of the square substrate. Annealing at 920 °C stimulates a continuous rotation of the hex where all angles between ±0.7° are simultaneously realized. At temperatures around 1080 °C, the nonrotated hex coexists with a hex that is rotated by about 0.75°. Annealing at temperatures around 1120 °C yield a locking of the hex in fixed rotation angles of 0.77°, 0.88°, and 0.94°. At temperatures around 1170 °C, the Pt(001)-hex-R 0.94° prevails as the energetically most favored form of the rotated hex.

  15. Study on 660-nm quasi-continuous-wave intracavity frequency-doubled Nd:YAG laser

    Institute of Scientific and Technical Information of China (English)

    Tao Wang(王涛); Jianquan Yao(姚建铨); Baigang Zhang(张百钢); Guiyan Zang(臧贵艳); Peng Wang(王鹏); Yizhong Yu(于意仲)

    2003-01-01

    A quasi-continuous-wave intracavity frequency-doubled Nd:YAG laser which operates at 660 nm is studied.By using a flat-flat laser cavity, 2 Kr-lamps, KTP crystal and an acousto-optically Q-switch, 2-W outputpower at 660 nm is obtained. The relationship between laser cavity length and output power is analyzed.

  16. PROCESS STUDY ON DEPHENOLIZATION OF BPA-PHENOL ADDUCT BY SOLID DECOMPOSITION REACTION%双酚A-苯酚加合物固相分解反应脱酚的工艺研究

    Institute of Scientific and Technical Information of China (English)

    刘宗章; 张敏华; 李传兆; 钱胜华; 谈遒

    1999-01-01

    The process condition of dephenolization of bisphenol A-phenol adduct is studied,by using the solid decomposition reaction on the basis of thermodynamic property of bisphenol A-phenol and the kinetics of solid decomposition reaction.The process condition is proposed with high quality bisphenol A product.A new method of dephenolization in the production of bisphenol A is developed.

  17. Exact Controllability for the Fourth Order Schr(o)dinger Equation

    Institute of Scientific and Technical Information of China (English)

    Chuang ZHENG; Zhongcheng ZHOU

    2012-01-01

    The boundary controllability of the fourth order Schr(o)dinger equation in a bounded domain is studied.By means of an L2-Neumann boundary control,the authors prove that the solution is exactly controllable in H-2(Ω) for an arbitrarily small time.The method of proof combines both the HUM (Hilbert Uniqueness Method) and multiplier techniques.

  18. To tilt or not to tilt: Correction of the distortion caused by inclined sample surfaces in low-energy electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Sojka, Falko, E-mail: falko.sojka@uni-jena.de [Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 5, 07743 Jena (Germany); Meissner, Matthias; Zwick, Christian; Forker, Roman [Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 5, 07743 Jena (Germany); Vyshnepolsky, Michael; Klein, Claudius; Horn-von Hoegen, Michael [University of Duisburg-Essen, Department of Physics, Lotharstr. 1, 47057 Duisburg (Germany); Fritz, Torsten, E-mail: torsten.fritz@uni-jena.de [Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 5, 07743 Jena (Germany)

    2013-10-15

    Low-energy electron diffraction (LEED) is a widely employed technique for the structural characterization of crystalline surfaces and epitaxial adsorbates. For technical reasons the accessible reciprocal space is limited at a given primary electron energy E. This limitation may be overcome by sweeping E to observe higher diffraction orders decisively enhancing the quantitative examination. Yet, in many cases, such as molecular films with rather large unit cells, the adsorbate reflexes become less pronounced at energies high enough to observe substrate reflexes. One possibility to overcome this problem is an intentional inclination of the sample surface during the measurement at the expense of the quantitative interpretability of then severely distorted diffraction patterns. Here, we introduce a correction method for the axially symmetric distortion in LEED images of tilted samples. We provide experimental confirmation for micro-channel plate LEED and spot-profile analysis LEED instruments using the (7×7) reconstructed surface of a Si(111) single crystal as a reference sample. Finally, we demonstrate that the correction of this distortion considerably improves the quantitative analysis of diffraction patterns of adsorbates since substrate and adsorbate reflexes can be evaluated simultaneously. As an illustrative example we have chosen an epitaxial monolayer of 3,4,9,10-perylenetetracarboxylic dianhydride on Ag(111) that is known to form a commensurate superstructure. - Highlights: • We introduce a method to correct distortions in LEED patterns of tilted surfaces. • Higher diffraction orders unobservable at higher beam energies can be evaluated. • Our procedure makes LEED patterns of tilted samples quantitatively analyzable. • Experimental confirmation with SPA-LEED and MCP-LEED is presented. • The method is applied to PTCDA on Ag(111) confirming earlier literature values.

  19. EXISTENCE AND EXPONENTIAL STABILITY OF ALMOST PERIODIC SOLUTIONS TO BAM RECURRENT NEURAL NETWORKS WITH TRANSMISSION DELAYS AND CONTINUOUSLY DISTRIBUTED DELAYS

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    In this paper,a class of bidirectional associative memory(BAM) recurrent neural networks with delays are studied.By a fixed point theorem and a Lyapunov functional,some new sufficient conditions for the existence,uniqueness and global exponential stability of the almost periodic solutions are established.These conditions are easy to be verified and our results complement the previous known results.

  20. Double Pyramidal Central Configurations with a Concave Quadrilateral Base

    Institute of Scientific and Technical Information of China (English)

    LIUXuefei

    2002-01-01

    As for a doudle pyramidal central configuration in 6-body problems,the case when its bese is a concave polygon is studied.By advancing several assumptions according to the definition of double pyramidal central configuration and deducing two theorems and two corollaries on this subject,the essential and sufficient conditions to form a double pyramidal central configuration with a concave quadriateral base are demonstrated.

  1. Coordination Structure of Aluminum in Magnesium Aluminum Hydroxide Studied by 27Al NMR

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The coordination structure of aluminum in magnesium aluminum hydroxide was studiedby 27Al NMR. The result showed that tetrahedral aluminum (AlⅣ) existed in magnesiumaluminum hydroxide, and the contents of AlⅣ increased with the increase of the ratio of Al/Mg andwith the peptizing temperature. AlⅣ originated from the so-called Al13 polymer with the structureof one Al tetrahedron surrounded by twelve Al octahedrons.

  2. An Analytical and Experimental Study of a Natural Circulation Loop with Horizontal Heating Section

    Institute of Scientific and Technical Information of China (English)

    YinxueSu; QingjinWu

    1994-01-01

    The thermal performance of a rectangular loop with a horizontal heating segment and a partly cooling vertical leg is studied.By one-dimensional approach,traditional friction factor and empirical correlation,a modified Grashof number Gr* which turns out to be very important in the description of circulation flow is introduced .A new correlation for Nusselt number of the horizontal heater is obtained and the comparison with experimental values shows good agreement.

  3. 非光滑向量优化中的Kuhn-Tucker型最优性条件%THE Khhn- Tucker OPTIMALITY CONDITIONS FOR NONSMOOTH VECTOR OPTIMIZATION

    Institute of Scientific and Technical Information of China (English)

    李月鲜; 刘海军

    2011-01-01

    本文研究实Banach空间中带有不等式约束的非光滑向量优化问题(VP).我们借助Farkas引理给出了问题(VP)的Kuhn-Tucker型最优性条件.在满足约束品性EMFCQ下,讨论了问题(VP)可行集的稳定性问题.%In this thesis, the nonsmooth vector optimization problems(VP) with inequality constraints in real Banach space are studied.By introducing Farkas lemma ,the Kuhn -Tucker optimality conditions are proposed.The stability of the problem(VP) are discussed again.

  4. Analytical investigation of the boundary-triggered phase transition dynamics in a cellular automata model with a slow-to-start rule

    Institute of Scientific and Technical Information of China (English)

    Jia Ning; Ma Shou-Feng; Zhong Shi-Quan

    2012-01-01

    Previous studies suggest that there are three different jam phases in the cellular automata automaton model with a slow-to-start rule under open boundaries.In the present paper,the dynamics of each free-flow-jam phase transition is studied.By analysing the microscopic behaviour of the traffic flow,we obtain analytical results on the phase transition dynamics.Our results can describe the detailed time evolution of the system during phase transition,while they provide good approximation for the numerical simulation data.These findings can perfectly explain the microscopic mechanism and details of the boundary-triggered phase transition dynamics.

  5. Regional pole assignment for uncertain delta-operator systems

    Institute of Scientific and Technical Information of China (English)

    Man LIU; Yuanwei JING; Siying ZHANG

    2004-01-01

    The pole assignment in a specified disk by state feedback for uncertain delta-operator systems is studied.By making use of algebra Riccati equations,a sufficient and necessary condition of pole assignment for a kind of parameter uncertain delta-operator system in a specified disk by state feedback is presented.And the design method of state feedback controller is also developed.The proposed method can unify some previous related results of continuous and discrete time systems into the delta framework.The efficiency of the design method is illustrated by a numerical example.

  6. Stabilization and trajectory tracking of autonomous airship's planar motion

    Institute of Scientific and Technical Information of China (English)

    Zhang Yan; Qu Weidong; Xi Yugeng; Cai Zili

    2008-01-01

    The stabilization and trajectory tracking problems of autonomous airship's planar motion are studied.By denning novel configuration error and velocity error,the dynamics of error systems are derived.By applying Lyapunov stability method,the state feedback control laws are designed and the close-loop error systems are proved to be uniformly asymptotically stable by Matrosov theorem.In particular,the controller does not need knowledge on system parameters in the case of set-point stabilization,which makes the controller robust with respect to parameter uncertainty.Numerical simulations illustrate the effectiveness of the controller designed.

  7. New robust chaotic system with exponential quadratic term

    Institute of Scientific and Technical Information of China (English)

    Bao Bo-Cheng; Li Chun-Biao; Xu Jian-Peing; Liu Zhong

    2008-01-01

    This paper proposes a new robust chaotic system of three-dimensional quadratic autonomous ordinary differential equations by introducing an exponential quadratic term.This system can display a double-scroll chaotic attractor with only two equilibria,and can be found to be robust chaotic in a very wide parameter domain with positive maximum Lyapunov exponent.Some basic dynamical properties and chaotic behaviour of novel attractor are studied.By numerical simulation,this paper verifies that the three-dimensional system can also evolve into periodic and chaotic behaviottrs by a constant controller.

  8. Nonlinear transport of Bose-Einstein condensates in a double barrier potential

    Institute of Scientific and Technical Information of China (English)

    Fang Jian-Shu

    2008-01-01

    The stable nonlinear transport of the Bose-Einstein condensates through a double barrier potential in a waveguide is studied.By using the direct perturbation method we have obtained a perturbed solution of Gross-Pitaevskii equation.Theoretical analysis reveals that this perturbed solution is a stable periodic solution,which shows that the transport of Bose-Einstein condensed atoms in this system is a stable nonlinear transport.The corresponding numerical results are in good agreement with the theoretical analytical results.

  9. Thermodynamical Properties of Spin-3/2 Ising Model in a Longitudinal Random Field with Crystal Field

    Institute of Scientific and Technical Information of China (English)

    LIANG Ya-Qiu; WEI Guo-Zhu; ZHANG Hong; SONG Guo-Li

    2004-01-01

    A theoretical study of a spin-3/2 Ising model in a longitudinal random field with crystal field is studiedby using of the effective-field theory with correlations. The phase diagrams and the behavior of the tricritical point areinvestigated numerically for the honeycomb lattice when the randorm field is bimodal. In particular, the specific heatand the internal energy are examined in detail for the system with a crystal-field constant in the critical region wherethe ground-state configuration may change from the spin-3/2 state to the spin-1/2 state. We find many interestingphenomena in the system.

  10. Martensitic Transformation of TiNi Shape Memory Alloy Fiber Reinforced Ni Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    Lishan CUI; Yan LI; Yan jun ZHENG; Huibin XU

    2003-01-01

    In this paper, a TiNi shape memory alloy fiber Ni matrix composite was fabricated by an electroplating method using TiNialloy as the cathode and Ni as the anode. The constrained martensitic transformation behaviors of the TiNi alloy were studiedby differential scanning calorimeter (DSC), and the results showed that two endothermic peaks appear on the DSC heatingcurves and the reverse transformation temperatures increase with increasing prestrain levels. Moreover, comparing to the freetransformation, the temperature window of the constrained reverse transformation is widely expanded due to the influence ofrecovery stress.

  11. CYCLOSTATIONARITY-BASED OFDM SIGNAL SENSING OVER DOUBLY-SELECTIVE FADING CHANNELS

    Institute of Scientific and Technical Information of China (English)

    Tian Jinfeng; Jiang Yonglei; Chen Huaxia; Hu Honglin

    2011-01-01

    In this paper,using cyclostationarity-based sensing method to detect the presence of Orthogonal Frequency Division Multiplexing (OFDM) signal over doubly-selective fading channels is studied.By approximating the channel with Basis Expansion Model (BEM),we derive the second-order cyclostationary statistics of the received OFDM signal over doubly-selective fading channels.Theoretical analysis indicates that new cyclostationary signatures produced by Doppler spread and multipath delay can be further exploited in the detecting process.Simulation examples demonstrate that the sensing methods using channel-induced cyclostationary features provide substantial improvements on detection performance.

  12. Investigation on characteristics of self-organization in Mach-Zehnder erbium-doped fiber laser cavity

    Institute of Scientific and Technical Information of China (English)

    Fengnian Liu; Bo Liu; Bangcai Huang; Guiyun Kai; Shuzhong Yuan; Xiaoyi Dong

    2008-01-01

    The characteristics of coherent coupling in Mach-Zehnder erbium-doped fiber laser cavity are experimentally studied.By virtue of a seemly controlling of length difference between two interferometric arms,the obtained comb-like spectrum of interferometer resonator with a period of 0.06 nm commendably agrees with the theory of self-organization coherence The coherent output exits from the output mirror of a fiber Bragg grating with 4.5% reflectivity.A high coherent combining efficiency of 94% is obtained.Investigation on characteristics of the leak power opens out self-organization mechanism in Mach-Zehnder composite cavity.

  13. Rabi Oscillations in Two-Component Bose-Einstein Condensates with a Coupling Drive

    Institute of Scientific and Technical Information of China (English)

    LI Wei-Dong; FAN Wen-Bing; ZHOU Xiao-Ji; WANG Yi-Qiu; LIANG Jiu-Qing

    2002-01-01

    The Rabi oscillations in two-component Bose-Einstein condensates with a coupling drive are studiedby means of a pair of bosonic operators. The coupling drive and initial phase difference will affect the amplitudeand the period of the Rabi oscillations. The Rabi oscillations will vanish in the evolution of the condensate densityfor some special initial phase differences (ψ = 0 or π). Our theory provides not only an analytical framework forquantitative predictions for two-component condensates, but also gives an intuitive understanding of some mysteriousfeatures observed in experiments and numerical. simulations.

  14. Bifurcations of Limit Circles and Center Conditions for a Class of Non-analytic Cubic Z2 Polynomial Differential Systems

    Institute of Scientific and Technical Information of China (English)

    Feng LI; Yi Rong LIU; Yin Lai JIN

    2012-01-01

    In this paper,bifurcations of limit cycles at three fine focuses for a class of Z2-equivariant non-analytic cubic planar differential systems are studied.By a transformation,we first transform nonanalytic systems into analytic systems.Then sufficient and necessary conditions for critical points of the systems being centers are obtained.The fact that there exist 12 small amplitude limit cycles created from the critical points is also proved.Henceforth we give a lower bound of cyclicity of Z2-equivariant non-analytic cubic differential systems.

  15. Topological Structure of Disclination Lines in 2—Dimensional Liquid Crystals

    Institute of Scientific and Technical Information of China (English)

    张慧; 杨国宏; 等

    2002-01-01

    Using φ-mapping method and topological current theory,the topological structure of disclination lines in 2-dimensional liquid crystals is studied.By introducing the strength density and the topological current of many disclination lines,it is pointed out that the disclination lines are determined by the singulaities of the director field,and topologically quantized by the Hopf indices and Brouwer degrees,Due to the equivalence in physics of the director fields n(x) and -n(x),the Hopf indices can be integers or half-integers,representing a generalization of our previous studies of integer Hopf indices.

  16. Coexistance of C40 and C54 TiSi2 during the solid state reaction of Ti/Mo/Si system

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The effect of a 0.9 nm Mo interlayer at the interface of Ti film depositedon a Si substrate on phase formation of TiSi2 during annealing has been studiedby using transmission electron micro-diffraction technique. When Ti/Mo/Si was an-nealed at low temperature as 550℃ for 30 min in Ar ambient, a metastable phase, i.e.,hexagonal C40 TiSi2, and the equilibrium phase, i.e., orthorhombic C54 TiSi2, wereboth detected. The experimental patterns of the C40 and C54 compare well with thesimulated ones.

  17. Synthesis and Characteristics of Organic Bentonite Gel

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The bentonite was modified using Ca-bentonite as a matrix and octadecyl/ hexadecyl ammoniumsized by dispersing it into the dimethyl benzene-methyl alcohol system fully.The optimum process conditions for organic modification were that the coating agent dosage is 22g/L, reaction time is 90 minutes and the pH value of pulp is 10.X-ray diffraction ( XRD ) analysis indicates that the d (001) value of the modified bentonite is 20.532A.The influence of gel temperature on its viscosity characteristic was studied.By analyzing the transmssion electron microscopy (TEM) images and observing the dispersed gel, the nanometer effect of the organic gel was discussed.

  18. Lane changing analysis for two-lane traffic flow

    Institute of Scientific and Technical Information of China (English)

    Tieqiao Tang; Haijun Huang; S.C.Wong; Rui Jiang

    2007-01-01

    In this paper,the two-lane traffic are studiedby using the lane-changing rules in the car-followingmodels.The simulation show that the frequent lanechanging occurs when the lateral distance in car fol-lowing activities is considered and it gives rise to oscil-lating waves.In contrast,if the lateral distance is notconsidered (or considered occasionally),the lane chang-ing appears infrequently and soliton waves occurs.Thisimplies that the stabilization mechanism no longer func-tions when the lane changing is permitted.Since theoscillating and soliton waves correspond to the unsta-ble and metastable flow regimes,respectively,our studyverifies that a phase transition may occur as a result ofthe lane changing.

  19. Attracting and Invariant Sets of Cohen-Grossberg-type BAM Networks%Cohen-Grossberg-type BAM神经网络吸引集和不变集(英文)

    Institute of Scientific and Technical Information of China (English)

    王金华; 向红军; 魏叶梅

    2012-01-01

    A class of Cohen-Grossberg-type BAM neural networks with distributed delays is studied.By applying the theory of matrix and inequality technique,we obtain some results about the attracting and invariant set of the considered system.Moreover,an examples is given to demonstrate the feasibility of the obtained results.%利用矩阵理论和不等式分析技巧,讨论了一类具分布时滞的Cohen-Grossberg型BAM神经网络的不变集和吸引集,获得了一些最新结果,并给出一个实例说明我们结果的可行性.

  20. Courses Studied by New York Librarianship Students Affect Their Perceived Readiness for Employment. A Review of: Creel, S. L., & Pollicino, E. B. (2012. Practitioners’ & LIS students’ perceptions on preparedness in the New York metropolitan area. Education for Information, 29, 53-69. doi: 10.3233/EFI-2010-0911

    Directory of Open Access Journals (Sweden)

    Kirsty Thomson

    2012-12-01

    Full Text Available Objective – To investigate whetherlibrarianship students felt ready to enter theworkforce, and whether practitioners feltrecent graduates were suitably prepared.Design – Survey.Setting – A university in New York City, andschool and public librarians working in theNew York metropolitan area.Subjects – 55 MLS students, 167 school librarypractitioners, and 181 public librarypractitioners.Methods – Students surveyed practitionersabout new graduates’ readiness to work aslibrarians. The students also assessed theirown readiness.Main Results – Detailed analysis of differencesbetween the responses of the four subjectgroups – public librarians, school librarians,public library students, and school librarystudents – for each of six survey statements isprovided. Practitioners and students felt thatschool librarianship graduates were moreprepared for work than public librarianshipgraduates. This may have been due todifferences in the practical components of theircourses.Conclusion – Preparedness for libraryemployment is related to the courses studiedby librarianship students.

  1. XRF Method Determination of Nickel 、Chrome、Antimony、Niobium、Molybdenum、Titanium、Vanadium、Lead in Molten iron%XRF 法测定铁水中镍铬锑铌钼钛钒铅

    Institute of Scientific and Technical Information of China (English)

    张莉; 苏红梅

    2014-01-01

    Sample preparation conditions and the XRF analysis conditions were studied,By XRF method for determining the content of Ni、Cr、Sb、Nb、Mo、Ti、V、Pb of molten iron. The method has fast speed,Less investment and better accuracy and precision,The results obtained with wet chemical analysis.%研究了样品制备条件和 XRF 的分析条件,采用 XRF 法测定铁水中 Ni、Cr、Sb、Nb、Mo、Ti、V、Pb 元素的含量。本法分析速度快,投资少,测量准确度和精密度较好,所得结果与湿法化学分析吻合。

  2. Melting Characteristics and Wettability of Binding Phase in Sinter

    Institute of Scientific and Technical Information of China (English)

    SHEN Feng-man; LI Guang-sen; DING Zhi-min; MU Lin

    2009-01-01

    The melting characteristics and wettability of the binding phase in high basicity sinter were studied.By changing nCaO:nFe2O3 (molar ratio of CaO to Fe2O3) as well as the percentage of MgO,SiO2,and Al2O3,the melting characteristics and wettability of the binding phase were discussed.The results indicated that the characteristic melting temperature was the lowest and wettability was the best at nCaO:nFe2O3=1:1 (without addition); the addition of MgO increased the characteristic melting temperature and contact angles; when the percentage of SiO2 or Al2O3 was 3%,the characteristic melting temperature was the lowest,whereas the contact angles increased with an increase in SiO2 and Al2O3 contents.

  3. Processing Technology of Duck Gizzard Flexible Packaging Snack Food%软包装鸭肫休闲食品的加工技术研究

    Institute of Scientific and Technical Information of China (English)

    韩海旺

    2011-01-01

    Duck gizzard of the flexible packaging snack food processing was studied.By single and orthogonal experiment,the results showed that the optimal producing conditions were as follows: Vacuum 0.075 MPa,Vacuum Tumbler 1 h,3 d curing,cook 8 min,sterilization%研究了软包装鸭肫休闲食品的加工技术,通过单因素和正交试验对其工艺进行了研究,确定了最佳的工艺条件:真空度0.075 MPa,真空滚揉1 h;腌制时间3 d;预煮8 min;杀菌温度110℃,杀菌时间20 min。

  4. Crack elongation and its width of large depth reinforced concrete beams

    Institute of Scientific and Technical Information of China (English)

    GUAN Jun-feng; ZHAO Shun-bo; HUANG Cheng-kui

    2010-01-01

    In order to meet the requirement of structural inspection,the crack spacing and crack width at various heights in the tensile zone of six large depth reinforced concrete beams were measured under several loading levels of serviceability state.The effects of the depth of normal section beams on the crack spacing and crack width were analyzed,and the modified model is proposed for calculating the average crack spacing by thinking about the depth of normal section,the reinforcement arrangement and the effective reinforcement ratio.The relationships of crack widths at any position in the tensile zone and at the reinforcement level on the side surface of beam were studied.By theoretical and statistical analysis,a method is proposed to calculate the ratios of crack widths between any position and the reinforcement level on the side surface of large depth reinforced concrete beams.

  5. A Method of Analyzing Transmission Losses in Left-Handed Metamaterials

    Institute of Scientific and Technical Information of China (English)

    WANG Jia-Fu; QU Shao-Bo; XU Zhuo; ZHANG Jie-Qiu; MA Hua; YANG Yi-Ming; GU Chao

    2009-01-01

    A method of analyzing transmission loss in left-handed metamaterials (LHMs) is proposed.As a demonstration of this method,transmission loss of LHMs composed of split-ring resonators (SRR) and conducting wires is studied.By means of retrieving and analyzing the effective constitutive parameters,different transmission losses as well as their origins are studied.The rssults show that the left-handed bandwidth is narrowed because of high loss caused by the non-zero high imaginary parts of the effective permeability and permittivity.In the effective left-handed band,the radiation loss is very low and can be neglected,and the transmission losses are the sum of the substrate loss and the ohmic loss.Moreover,when the dielectric loss tangent of the substrate is greater than 0.003,the substrate loss is higher than the ohmic loss.

  6. Dynamic Behaviors of a Discrete Predator-prey Model Incorporating Harvesting and Toxicity%一类离散有毒素和捕获的捕食系统动力学行为

    Institute of Scientific and Technical Information of China (English)

    伍慧玲

    2012-01-01

    研究一类具有离散时间、外界捕获、毒素作用的捕食-食饵系统,通过运用比较引理和构造恰当的Lyapunov函数,证明了系统的持久性和全局吸引性,最后,我们给出了捕食者、食饵种群绝灭的充分条件.%A discrete predator-prey model with harvesting and toxicity was studied.By using comparison theorem and constructing a suitable Lyapunov function,the permanence and global attractivity of the system were proved.Sufficient conditions for the extinction of the predator and prey were given.

  7. Pilot Based Channel Estimation in IEEE 802.16a OFDM System

    Institute of Scientific and Technical Information of China (English)

    ZHU Qi; LU Hao

    2005-01-01

    Orthogonal Frequency Division Multiplexing(OFDM)is a kind of transmission techniques with high frequency efficiency,which will be widely used in next-generation wireless communication systems.In this paper,pilot-based channel estimation for IEEE 802.16a OFDM system is studied.By comparing the performance of LS(least squares)estimator and Linear Minimum Mean-Square Error(LMMSE)estimator using Preamble 1 and Preamble 2 suggested by IEEE 802.16a standard in slow fading channel,we propose that Preamble 1 can be used in small multipath delay spread channel and Preamble 2 can be used in large multipath delay spread channel.Considering the tradeoff between performance and complexity,the LS estimator is suggested.

  8. THE STUDY ON MECHANISM OF BINDER MIGRATION DURING COATING PROCESS

    Institute of Scientific and Technical Information of China (English)

    YunLiang; KefuChen

    2004-01-01

    Binder migration during coating process and themechanism of binder migration were studied in thispaper. After the latex was tagged by osmium, thedegree of binder migration was measured byenergy-dispersive X-ray spectrometer. For the wetsample just after coating application, the realinformation of binder distribution was kept byquenching the sample in liquid nitrogen followed byfreeze-drying. The results showed: under thecondition of this research, binder migration occurredboth in the process of coating application and drying.But the amount of binder migration occurred duringcoating application was much little than that occurredduring drying. The mechanism of binder migrationduring the process of coating application was studiedby force analyses. And one viewpoint was proposedthat was binder migration was caused by Magnusforce and Saffman force.

  9. SUPERCONVERGENCE OF DG METHOD FOR ONE-DIMENSIONAL SINGULARLY PERTURBED PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    Ziqing Xie; Zhimin Zhang

    2007-01-01

    The convergence and superconvergence properties of the discontinuous Galerkin (DG) method for a singularly perturbed model problem in one-dimensional setting are studied.By applying the DG method with appropriately chosen numerical traces, the existence and uniqueness of the DG solution, the optimal order L2 error bounds, and 2p+1-order superconvergence of the numerical traces are established. The numerical results indicate that the DG method does not produce any oscillation even under the uniform mesh. Numerical experiments demonstrate that, under the uniform mesh, it seems impossible to obtain the uniform superconvergence of the numerical traces. Nevertheless, thanks to the implementation of the so-called Shishkin-type mesh, the uniform 2p + 1-order superconvergence is observed numerically.

  10. Topological Aspect and Bifurcation of Disclination Lines in Two—Dimensional Liquid Crystals

    Institute of Scientific and Technical Information of China (English)

    YANGGuo-Hong; ZHANGHui; 等

    2002-01-01

    Using φ-mapping method and topological current theory,the topological structure and bifurcation of disclination lines in two-dimensional liquid crystals are studied.By introducing the strength density and the topological current of many disclination lines,the total disclination strength is topologically quantized by the Hopf indices and Brouwer degrees at the singularities of the director field when the Jacobian determinant of director field does not vanish.When the Jacobian determinant vanishes,the origin,annihilation and bifurcation processes of disclination lines are studied in the neighborhoods of the limit points and bifurcation points,respectively.The branch solutions at the limit point and the different directions of all branch curves at the bifurcation point are calculated with the conservation law of the topological quantum numbers.It is pointed out that a disclination line with a higher strength is unstable and it will evolve to the lower strength state through the bifurcation process.

  11. Study on extraction of inulin from jerusalem artichoke with pectinase%果胶酶浸提菊芋菊糖的研究

    Institute of Scientific and Technical Information of China (English)

    李雪雁; 陈晓前; 王玉丽

    2009-01-01

    Extraction of inulin with pectinase was studied.By means of orthogonal design,optimum parameters were confirmed as solid to liquid ratio 1 : 14, pectinase concentration 0.5%, extraction temperature 45℃, pH 4.0 and extraction time 120min.Under such condition,the average extracting rate of inulin was 11.56% ,it was more than the rate with hot water.%对果胶酶提取菊糖的工艺进行了研究.采用正交实验设计优化提取条件,确定固液比为1:14、添加果胶酶的浓度为0.5%、处理温度45℃、pH4.0、提取时间120min为最佳的提取工艺,在此条件下,菊糖的提取率平均为11.56%,高于热水浸提的提取率.

  12. Estimation of snow cover distribution in Beas basin, Indian Himalaya using satellite data and ground measurements

    Indian Academy of Sciences (India)

    H S Negi; A V Kulkarni; B S Semwal

    2009-10-01

    In the present paper,a methodology has been developed for the mapping of snow cover in Beas basin,Indian Himalaya using AWiFS (IRS-P6)satellite data.The complexities in the mapping of snow cover in the study area are snow under vegetation,contaminated snow and patchy snow. To overcome these problems,field measurements using spectroradiometer were carried out and reflectance/snow indices trend were studied.By evaluation and validation of different topographic correction models,it was observed that,the normalized difference snow index (NDSI)values remain constant with the variations in slope and aspect and thus NDSI can take care of topography effects.Different snow cover mapping methods using snow indices are compared to find the suitable mapping technique.The proposed methodology for snow cover mapping uses the NDSI (estimated using planetary re flectance),NIR band reflectance and forest/vegetation cover information.The satellite estimated snow or non-snow pixel information using proposed methodology was validated with the snow cover information collected at three observatory locations and it was found that the algorithm classify all the sample points correctly,once that pixel is cloud free.The snow cover distribution was estimated using one year (2004 –05)cloud free satellite data and good correlation was observed between increase/decrease areal extent of seasonal snow cover and ground observed fresh snowfall and standing snow data.

  13. 酸枣果醋酒精发酵过程工艺的研究%Study on technology of alcohol fermentation in wild jujube vinegar

    Institute of Scientific and Technical Information of China (English)

    毛丽衡; 毛永民; 王颉; 申连英; 刘亚琼; 王晓玲

    2013-01-01

    以酸枣果肉为原料,采用液态酒精-固态醋酸发酵法研制果醋,对酸枣果醋酒精发酵的过程进行研究.通过单因素和正交实验,得出酒精发酵最佳发酵条件,即含糖量15%,温度29.℃,酵母接种量0.08%,pH3.5,磷酸氢二铵添加量4g/L,酒精度可达到8.7%.实验结果可以为酸枣果醋饮料产品的进一步开发提供一定依据.%Fruit vinegar was produced using wild jujube as a raw material after liquid fermentation of alcohol and solid fermentation of acetic acid.The main processing technology and conditions of alcohol fermentation were studied.By single factor experiment and the orthogonal experiment,the best alcohol fermentation conditions were obtained,for sugar 15%,fermentation temperature 29℃,inoculum concentration 0.08%,pH3.5,diammonium phosphate concentration 4g/L,the alcoholic strength could reach 8.7%.Results showed that these technology foundations could be used for the further development of lemon vinegar drinks.

  14. 广义行(列)对称矩阵的Moore-Penrose逆%The Moore-Penrose Inverse for Generalized Row(Column)Symmetric Matrix

    Institute of Scientific and Technical Information of China (English)

    郭伟

    2012-01-01

    The concept of generalized row(column)symmetric matrix is given,its full rank decomposition and singular value decomposition are studied.By the two decompositions and orthogonal equivalence,three shortcut counting methods of the Moore-Penrose inverse for generalized row(column)symmetric matrix are obtained,which can dramatically reduce the amount of calculation and save the CPU time and memory,which extend the results of the related references and which spread its application scope.%提出了广义行(列)对称矩阵概念,研究了它的满秩分解和奇异值分解,利用这两种分解以及正交相抵,得到3种广义行列对称矩阵Moore-Penrose逆的快速算法,可极大节省其计算量和存储量;推广了相关文献的结果,使其应用范围更广.

  15. 紫薯生物饮料的研制%Preparation of Purple Sweet Potato Biological Beverage

    Institute of Scientific and Technical Information of China (English)

    徐峰

    2016-01-01

    With purple sweet potato as the main material,the technology of preparing purple sweet potato biological beverage was stud-ied.By single factor experiment and orthogonal test,the optimum purple sweet potato beverage formula was 4% sucrose,0.15% citric acid and 0.15% Composite stabilizers(CMC -Na :xanthan gum :agar =1:1:1).After optimization,the beverage featured by bright color,good taste,rich nutrition and it is one kind of potential biological beverage.%以紫薯为原料,对紫薯生物饮料加工工艺进行研究.通过单因素与正交实验确定了紫薯饮料的最佳调配工艺参数为:蔗糖添加量为4%,柠檬酸添加量为0.15%,复合型稳定剂(CMC -Na∶黄原胶∶琼脂=1∶1∶1)添加量为0.15%.此工艺参数下制作的紫薯饮料色泽鲜艳、口感良好、营养丰富并且具有一定的市场发展潜力.

  16. The design of recycled waste fiber nonwovens manufacturing honeycomb sandwich structure%再生废旧纤维非织造布制造蜂窝夹层结构的设计

    Institute of Scientific and Technical Information of China (English)

    许兰涛; 王山英; 粘伟诚; 田雨胜; 吴晓青

    2013-01-01

    Basing various plain press damage way of the material , via reduction of plain press damage formula the structure design of the recycled waste fiber nonwovens manufacturing honeycomb sandwich structure material was studied.By the property parameter of the nonwovens , through calculation and design the ratio of wall thickness/honeycomb length ts c =0.03, the theory plain press strength of the material would be the highest, in this condition, the nonwovens with honeycomb sandwich structure was designed .%  根据材料不同的平压破坏形式,通过对平压破坏方程的推导,对用再生废旧纤维制造的非织造布蜂窝夹层结构材料的结构设计进行了研究。依据非织造布的性能参数,通过计算得出了蜂壁厚度ts/蜂窝边长c为0.03时蜂窝夹层结构材料的理论平压强度最大,设计时非织造布蜂窝边长c与蜂壁厚度ts按满足ts c =0.03条件取值均可。

  17. Determination of sesamin and sesamolin in sesame using HPLC with C18 purification%C18净化-HPLC测定芝麻中芝麻素和芝麻林素含量

    Institute of Scientific and Technical Information of China (English)

    陈伟; 刘红彦; 倪云霞

    2011-01-01

    采用HPLC测定芝麻中芝麻素和芝麻林素含量,对超声波提取芝麻中芝麻素和芝麻林素的条件进行了研究,同时探讨了提取液净化处理对其测定结果的影响.通过单因素及正交试验,确定超声波最佳提取条件为:提取剂V(正己烷)/V(甲醇)=60:40,液料比30:1,超声提取温度65℃,超声提取时间12min.采用C18时样品进行净化处理,可提高净化效果,减少测定干扰.%The content of sesamin and sesamolin in sesame were determined by HPLC ,and the conditions of the ultrasonic - assisted extraction of the two substances were studied.By the single factor experiments and orthogonal experiments, the extraction conditions were optimized as follows: n - hexane - MeOH ( volume ratio 60∶ 40) as extraction solvent, ratio of liquid to material 30∶ 1, extraction temperature 65 ℃, ultrasonic extraction time 12 min.The C18 adopted in the pre - processing of sample could enhance the purification effect and decrease the inspectional molestation.

  18. On Crystallization in Polypropylene-Polyethylene Blends

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Blends of polypropylene(PP) and low-density polyethylene (LDPE) have beencrystallized to form open structures(“cluster spherulites”) where the droplets of the minorityPP are bridged by PP lamellae which have grown in the LDPE-rich matrix. These are studiedby permanganic etching followed by electron and optical microscopies. Two similar PP typesare compared, one synthesized with Ziegler-Natta catalyst and one with metallocenecatalyst. The metallocene-catalysed material crystallized much more slowly due to thepresence of regio defects in the chains, even though the overall concentration of tacticitydefects in the Ziegler-Natta material is much higher. A mechanism involving reversal ofhelical direction at the regio defect interfering with the regular chain packing in the crystal issuggested. Growth of “cluster spherulites” is faster in regions where low molecular weightmaterial is concentrated. It is slower where droplets are larger, and this is attributed tocompetition between PP lamellar growth in the matrix and diffusion of PP to alreadycrystallized droplets.

  19. Technology development and application of asepsis cool-filling desserts%无菌冷罐装含乳甜点的技术开发和应用

    Institute of Scientific and Technical Information of China (English)

    胡姝敏; 朱雅玲

    2013-01-01

    Abstracts:The technology development and application of asepsis cool-filling desserts that fit for China were studied.By studying technical characters of asepsis cool-filling desserts and relative hydrocolloids application character,the technology (parameter),technology flow and hydrocolloids were confirmed,and the hydrocolloids were composed for functional system applied for asepsis cool-filling desserts to produce desserts that have very good texture and sensory organ property,including neutrosphere chocolate dessert and acidic pudding dessert.%研究了适合我国现有生产条件和市场发展状况的无菌冷灌装甜点的技术与应用.通过研究无菌冷灌装甜点的工艺特征及相关胶体应用特征,选择适合的亲水胶体,通过科学实验设计和生产验证,完成了利用超高温灭菌和无菌罐装技术生产不同质构的含乳甜点的工艺流程和稳定体系的设计.

  20. A microchip to analyze single crystal growth and size-controllability

    Institute of Scientific and Technical Information of China (English)

    PANG YuanFeng; LIU JiangJiang; LI HaiFang; LIN JinMing

    2009-01-01

    A microfluidic device to control single crystallization on the micron scale has been developed.The salt solution was stored in the nano-volume gaps between the arrays of protrudent circular plots in the microchip.The mixed organic solvent was injected into the chip as the counter diffusion phase for crystallization forming.This device provides a liquid-liquid interface through which only one phase flows while the other stays at the fixed plot.Therefore,it is possible to control the position of crystallization on the fixed plot.We can control the size and the uniformity of single crystals from 5 to 50 μm in length by adjusting the relative factors,such as interface lifetime,breeds of the mix-organic solvents and inject- ing velocities.The longer interface lifetime and lower organic solvent injecting velocities can bring up larger and more asymmetric crystals,which nearly shows the same trend compared with the macroscopic crystallization.Finally,the effect of the surfactant on the crystallization in the micro-device was studied.By adding the surfactant into the liquid-liquid interface,smaller sizes of crystals can be obtained without changing the crystal configuration.

  1. Research and development on water model test of KR stirring desulphurization transmission dynamics%KR搅拌脱硫传输动力学水模实验研究及进展

    Institute of Scientific and Technical Information of China (English)

    欧阳德刚; 朱善合; 李明晖; 罗巍; 田大鹏

    2011-01-01

    综述了国内外KR搅拌脱硫流动状态与混合特性的理论及水模实验研究结果,探明了改善KR搅拌脱硫混合效果的主要手段和其局域卷吸混合分散特性;通过介绍国内外改善KR搅拌脱硫动力学条件的水模实验方法、研究结果与实践效果,分析了改善KR搅拌脱硫动力学条件的有效措施,证明了水模实验结果对实际生产的推动作用。%By summarizing the theory and water model test research results about flowing state and properties of agitated mixing of KR stirring desulphurization at home and abroad,the main measures to improve the immixture effect and the mixed dispersing performance of immixture in location area were studied.By introducing the methods and results of water model experimental research of KR stirring desulphurization and practice effects,the measures to improve the reaction dynamics condition of KR stirring desulphurization were proposed,and it proved that the result of water model test can promote the development of production.

  2. Synchronization of three homodromy coupled exciters in a non-resonant vibrating system of plane motion

    Institute of Scientific and Technical Information of China (English)

    Xue-Liang Zhang; Bang-Chun Wen; Chun-Yu Zhao

    2012-01-01

    In this paper,the synchronization problem of three homodromy coupled exciters in a non-resonant vibrating system of plane motion is studied.By introducing the average method of modified small parameters,we deduced dimensionless coupling equation of three exciters,which converted the problem of synchronization into that of the existence and stability of zero solutions for the average differential equations of the small parameters.Based on the dimensionless coupling torques and characteristics of the corresponding limited functions,the synchronization criterion for three exciters was derived as the absolute value of dimensionless residual torque difference between arbitrary two motors being less than the maximum of their dimensionless coupling torques.The stability criterion of its synchronous state lies in the double-condition that the inertia coupling matrix is positive definite and all its elements are positive as well.The synchronization determinants are the coefficients of synchronization ability,also called as the general dynamical symmetry coefficients.The double-equilibrium state of the vibrating system is manifested by numeric method,and the numeric and simulation results derived thereof indicate the indispensable and crucial role the structural parameters of the vibrating system play in the stability criterion of synchronous operation.Besides,by adjusting its structural parameters,the elliptical motion of the vibrating system successfully met the requirements in engineering applications.

  3. A novel weighted evolving network model based on clique overlapping growth

    Institute of Scientific and Technical Information of China (English)

    YANG Xu-hua; WANG Bo; SUN Bao

    2010-01-01

    A novel weighted evolving network model based on the clique overlapping growth was proposed.The model shows different network characteristics under two different selection mechanisms that are preferential selection and random selection.On the basis of mean-field theory,this model under the two different selection mechanisms was analyzed.The analytic equations of distributions of the number of cliques that a vertex joins and the vertex strength of the model were given.It is proved that both distributions follow the scale-free power-law distribution in preferential selection mechanism and the exponential distribution in random selection mechanism,respectively.The analytic expressions of exponents of corresponding distributions were obtained.The agreement between the simulations and analytical results indicates the validity of the theoretical analysis.Finally,three real transport bus networks(BTNs)of Beijing,Shanghai and Hangzhou in China were studied.By analyzing their network properties,it is discovered that these real BTNs belong to a kind of weighted evolving network model with clique overlapping growth and random selection mechanism that was proposed in this context.

  4. Clean环中的几个上三角矩阵环%Several Upper Triangular Matrix Rings of Clean Rings

    Institute of Scientific and Technical Information of China (English)

    温立书

    2013-01-01

    Several upper triangular matrix rings of clean rings were studied.By the definition of a clean ring (with 1) is extended to any ring (not necessarily with 1),some results were proved:Let R be a clean ring,and let G be a group of order 2,then group ring RG is also a clean ring under some conditions.Several upper triangular matrix rings are strongly clean rings.Then several results of clean rings were extended; some upper triangular matrix rings are a strongly f-clean rings.%研究了clean环中的几个上三角矩阵环.通过将clean环的定义推广到任意环(不必有1),得到若R是clean环,G是阶为2的群,满足一定条件,群环RG也是clean环;证明了一些上三角矩阵环是强clean环.最后推广了一些结论,得到一些上三角矩阵环是强f-clean环.

  5. Analysis of streamwise conduction in forced convection of microchannels using fin approach

    Institute of Scientific and Technical Information of China (English)

    Suhandran MUNIANDY; Yew Mun HUNG

    2011-01-01

    The effects induced by streamwise conduction on the thermal characteristics of forced convection for single-phase liquid flow in rectangular microchannel heat sinks under imposed constant wall temperature have been studied.By employing the fin approach in the first law of analysis,models with and without streamwise conduction term in the energy equation were developed for hydrodynamically and thermally fully-developed flow under local thermal non-equilibrium for the solid and fluid phases.These two models were solved to obtain closed form analytical solutions for the fluid and solid temperature distributions and the analysis emphasized details of the variations induced by the streamwise conduction on the fluid temperature distributions.The effects of the Peclet number,aspect ratio,and thermal conductivity ratio on the thermal characteristics of forced convection in microchannel heat sinks were analyzed and discussed.This study reveals the conditions under which the effect of streamwise conduction is significant and should not be neglected in the forced convective heat transfer analysis ofmicrochannel heat sinks.

  6. Effects of reduction of diameter on microstructure and surface roughness of rotary swaged magnesium by FEA

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Combining the processing maps with FEA,the critical values of reduction of diameter(△R)for the appearance of as-cast microstructure,dynamic recrystallization grains and twins in the swaged magnesium were respectively studied,by which the rational range of AR was obtained.To ensure that the as-cast microstructure wouldn't be retained in the rotary-swaged magnesium.△R shouldbe larger than 0.25 mill.To avoid the appearance of twins in the microstructure of rotary-swaged magnesium.△R should be less than 1.0 mm.△R should be between 0.25 mm and 1.0 mm to ensue the appearance of recrystallized grains.The surface roughness of rotary-swaged magnesium increases with the increase of △R by quadratic function.The simulated results accord well with the experimental data.In the process control of rotary-swaging(RS),△R should be maximized between 0.25 mm and 1.0 mm on the precondition that the requests for surface roughness have been satisfied.

  7. Research on pulse edge extraction by using nonlinear optical fiber-loop mirror

    Institute of Scientific and Technical Information of China (English)

    PENG Yong-jun; QIU Kun; JI Si-wei

    2012-01-01

    The output characteristics of nonlinear optical fiber-loop mirror are analyzed in detail when the pump pulses with the same wavelength are input in the both directions for recovering the clock component of the signal spectrum.It is found that the double output pulses are produced in the transmission port of the nonlinear optical fiber-loop mirror.The output pulse peaks are located in time domain at the rising and falling edges of the pump pulses.It is demonstrated that the rising and falling edges of the pump pulse can be directly extracted by this method.Through numerical simulation,the effects of the relative delay of pump pulses and the dispersion of fiber on the characteristics of output pulses are studied.By spectrum analysis,it is found that the spectrum of output pulse sequence includes the clock components of the pump pulse sequence,and a new idea is provided for all-optical clock extraction.

  8. 新型耐磨焊条在破碎机上的应用%A New Type Electrode for Shredders

    Institute of Scientific and Technical Information of China (English)

    应鹏展; 王雅晴

    2001-01-01

    A wear-resistant electrode used in high stress state is studied.By adjusting electrode's component,we find a alloy system which is suitable to shredders with hammer.Microstructure and X-ray analyses indicate that the hardfacing microstructure consist of martensite,retained austenite and carbonide. The hardfacing hardness is between HRC62~64.Wearing resistance test and industrial practice had proved that wear-resistant of the hardfacing is 8.2 times as high as 45 steel's and its average service life can be prolonged by eight times longer than that of conventional way.%研制了一种适用于高冲击条件下抗磨堆焊焊条,通过反复调整焊条药皮组成,找到了可应用于锤式破碎机锤头堆焊的合金系。通过堆焊层的金相显微分析及X—射线物相分析表明:堆焊层组织为马氏体加碳化物加残余奥氏体,堆焊层的硬度为HRC62—64;高应力磨料磨损实验和工业试验证明:锤头堆焊合金的耐磨性能优良,是45钢的8.1倍,比未堆焊的锤头寿命提高了8倍。

  9. MORPHOLOGICAL FEATURES AND MORPHOMETRIC PARAMETERS OF HUMAN FETAL VERMIFORM APPENDIX AT DIFFERENT GESTATIONAL

    Directory of Open Access Journals (Sweden)

    Reshma.Mohammad

    2013-09-01

    Full Text Available Background:Vermiform appendix is a vestigial organ of variable position in the abdomen. Its location, size andshape are subject to alterations with the race of the population and limited information is available on devel-opmental morphology and morphometry of fetal appendix.Materials and Methods:In the present study 60appendix specimens from aborted human fetuses of 17-40 weeks gestational age and both sexes were studiedby dissection method for age related morphological features and morphometric parameters. The morphologi-cal parameters observed include its location in relation to abdominal region, caecum and ileum, clock position,position of base in relation to caecal wall and direction of tip of appendix. The morphometric parameters oflength, diameter and distance between ileo-caecal orifice and appendicular orifice were measured.Results:The location of appendix in relation to abdominal region presented higher incidence of sub-hepatic position inless than 30 weeks fetuses and right iliac fossa location in more than 30 weeks fetuses.Discussion: in comparisionwith the literature available on adult vermiform appendix the observations in the present study arein favor ofinfluence of developmental processes on the localization of appendix including its base, ileo-caecalorifice,direction of tip, distance from McBurney’s point.Conclusion:Results of this work suggests variability in local-ization of appendix during prenatal development and the influence of gestational age, sex, size, growth ofcaecum and gut on its final position and was different from that of adults. There is increase in themorphomet-ric parameters of appendix with increase in gestational age. Both morphological and morphometric param-eters were different between sexes.

  10. Study of photosynthesis process in the presence of low concentrations of clomazone herbicide in tobacco (Nicotiana tabacum

    Directory of Open Access Journals (Sweden)

    Darwish, Majd

    2013-02-01

    Full Text Available The effect of chemical residues of clomazone on photosynthetic processes has been studiedby using several low concentrations of the herbicide (0, 1, 0.1, 0.01, 0.001, 0.0001 and 0.00001 µM and seedlings of two varieties of tobacco (Nicotiana tabacum L. cv. Virginie vk51, Nicotiana tabacum, L. cv. Xanthi. The content of photosynthetic pigments, the parameters of the chlorophyll-a fluorescence and the JIP-test were performed on an adult leaf (AL and a young leaf (YL, that gave a complementary designto know the action's mode of clomazone on the plant physiological processes. Clomazone reducedthe total chlorophyll (a+b, carotenoids pigments (reduction in size antenna pigments judged by an increase in the chlorophyll a/b ratio in young leaves more than adults leaves. The maximal photochemical efficiency (Fv/Fm of photosystem II (PSII decreased significantly in youngleavescompared to adult leaves and in (Virginie variety than (Xanthi variety. Among the parameters calculated of the JIP-test most affected by the treatment, PIabs, 1-VJ, ABS/RC, DI0/RC, TR0/RC, ET0/RC, ET0/ABS, which indicated acomparable effects of clomazone(1μM, 0.1µM, 0.01µM between the two types of leaves and the varieties used. More, the results showed that the concentration ( 1μM was the most effective amongthe other low concentrations used and the (Virginie variety ismore sensitive than the (Xanthivariety. We conclude that clomazone has probably two combined functions (physiological, toxic judged by the different behavior of both types of leaves in the presence of the herbicide.

  11. Experimental Study on Mineral Processing of Low-grade Cu-Ni Ore%某低品位铜镍矿选矿试验研究

    Institute of Scientific and Technical Information of China (English)

    王潇

    2012-01-01

    A low-grade copper-nickel sulfide ore contains nickel 0.63 %,copper 0.62 %,and there are a lot of magnesium oxide minerals in the gangue minerals,including olivine,serpentine,chlorite,pyroxene,etc.According to mineral characters,the flotation test of the ore is studied.By experimenting,regulating and optimizing the technical parameter,we use the site production process and gets the qualified concentrate: nickel grade was 6.11 %,nickel recovery rate reaches 72.03 %,and copper grade was 7.06 %,copper recovery rate reaches 78.61 %.That not only improves resource utilization,but also provides a reasonable way for sustainable development of mineral enterprise.%某低品位硫化铜镍矿含镍0.63%、含铜0.62%,脉石矿物主要以橄榄石、蛇纹石、绿泥石、辉石等含镁矿物为主。根据矿石性质,对其进行了浮选试验研究,采用现场生产工艺流程,通过试验调整、优化工艺参数后得到了镍品位6.11%、回收率72.30%和铜品位7.06%,回收率78.61%的合格精矿,提高了资源利用率,为矿山可持续发展提供了合理的途径。

  12. 专利保护对考虑市场细分闭环供应链的影响%Effect of Patent Protection on Closed-Loop Supply Chain with Market Segmentation Considered

    Institute of Scientific and Technical Information of China (English)

    熊中楷; 黎雪

    2013-01-01

    在细分绿色消费者和普通消费者的基础上,研究了原始设备制造商(OEM)生产新产品和再制造商生产再制造品时,OEM征收再制造专利许可费对OEM与再制造商相互竞争的供应链的影响.分别构建了征收专利许可费和不征收专利许可费两种情形下的供应链定价模型,求得了OEM和再制造商的最优定价策略以及OEM的最优专利许可费征收策略,并对征收专利许可费和不征收专利许可费两种情形下的最优决策进行了比较分析.通过数值仿真,分别分析了绿色市场份额大小和普通消费者对再制造品的接受度对最优专利许可费、产品销售价格、供应链成员利润的影响.%By segmenting green consumer and primary consumer,the effect of patent protection on closedloop supply chain where OEM competes with an independent remanufacturer is studied.By establishing supply chain pricing models with and without patent protection fee,optimal pricing strategy and optimal protection fee decision strategy are derived.Comparison is made between the two different models.By using numerical simulation,the impacts of the degree of primary consumer acceptance to remanufactured products,the impacts of the green consumer share on the optimal price,profit,and patent protection fee are analyzed,respectively.

  13. Processing technology of new type papaya milk tablets%新型番木瓜奶片的研制

    Institute of Scientific and Technical Information of China (English)

    王菲; 黄苇; 郑妙慈

    2011-01-01

    The processing technique of compound papaya-milk tablets was studied.By investigating physical characteristics of the compound papaya-milk tablets via the single factor test and the L9(33)orthogonal experiment,the optimal seasoning recipe conditions were determined as follows:raw material ratio of milk powder and carica papaya powder 3∶ 1,the particle size of 20 ~ 40 mesh,maltose 30%,xylitol 20%,citric acid 0.3%,magnesium stearate dosage of 0.5%,raw material ratio of carica papaya essential oils and ethanol and water 1∶ 1∶ 1.The best quality milk tablets can be made with drying time of 6h and drying temperature of 70℃.%以番木瓜、奶粉为原料,研究了其复合奶片的制作工艺。以奶片的感官评定为指标进行单因素对比实验以及L9(33)正交优化实验,得出复合奶片最佳调味配方为:奶粉与番木瓜粉的配比为3∶1,颗粒的粒度20~40目,麦芽糖、木糖醇、柠檬酸、硬脂酸镁的添加量分别为30%、20%、0.3%、0.5%,番木瓜香精∶乙醇∶水为1∶1∶1;湿粒干燥时以70℃干燥6h,得到的奶片质量最佳,具有番木瓜香味和奶香味,口感细腻柔滑。

  14. Study and Realization of Fault Diagnosis for CRDM in PWR Nuclear Power Station%压水堆核电站CRDM故障诊断研究与实践

    Institute of Scientific and Technical Information of China (English)

    昌正科; 董治国; 常乐莉

    2013-01-01

    The fault diagnosis method for control rod drive mechanism (CRDM) in pressurized water reactor nuclear power station is studied.By using virtual instrument technology,the coil current waveform of CRDM is monitored on line,then the characteristics of the waveform and movement point are analyzed and recognized,thus the operating status of the drive mechanism and its current regulating output loop are judged.The analysis results are saved in real time database for long term performance trending analysis.The system is significant to enhance the operation reliability of CRDM,and has been applied in Qinshan Phase Ⅱ Nuclear Power Plant,it possesses better promotion value.%对压水堆核电站控制棒驱动机构故障诊断方法进行了研究.通过采用虚拟仪器技术,在线监测控制棒驱动机构线圈电流波形、分析波形特征、辨识驱动机构动作特征点,从而判断驱动机构及其电流调节输出回路的运行情况.分析结果实时保存到数据库,可用于驱动机构性能变化趋势的长期分析.系统对提高控制棒驱动机构运行可靠性具有重要意义,已成功应用于秦山第二核电厂,具有一定的推广价值.

  15. Synthesis of Cinnamic Acid%肉桂酸的合成工艺研究

    Institute of Scientific and Technical Information of China (English)

    刘鸿雁; 于丽颖

    2012-01-01

    研究了以吡啶为缩合剂,通过苯甲醛与丙二酸的Knoevenagel缩合反应合成肉桂酸的路线,以产物的收率作为考察指标,采用单因素多水平方法,分别研究了反应物配比、缩合剂用量、反应温度、反应时间等因素对收率的影响,确定了最佳工艺条件。最佳工艺条件下的肉桂酸收率达95%以上,并采用红外光谱对目标产物结构进行表征。该路线具有工艺简单,产率高,反应污染小,产物分离纯化容易,操作方便等优点。%The characters of the paths were summarized,and the path of using pyridine as condensation agent,benzaldehyde and malonic acid by Knoevenagel condensation reaction was mainly studied.By using the method of single-factor and multi-levels,the yield of cinnamic acid as an index,the reaction conditions such as catalyst ratio,reactant ratio,reaction temperature,reaction time were examined to give the preferable process.In the preferable process,the yield of cinnamic acid was 95%.The result was characterized by infrared spectrum and the structure was verified with HPLC.This path was simple,with high yield and less pollution.

  16. Studies on Purple Corn Pigment Extraction Process and Product Stability%紫玉米色素的提取工艺及产品稳定性研究

    Institute of Scientific and Technical Information of China (English)

    李传欣; 张宏宇; 李纯

    2012-01-01

    以紫玉米为原料提取紫玉米色素,并对产品稳定性进行研究。通过单因素试验,确定各工艺参数对紫玉米色素提取率的影响;选择提取温度、提取时间和料液比3个因素进行正交试验设计,对紫玉米色素的提取工艺进行优化。试验结果表明:影响紫玉米色素提取率的因素主次顺序为提取温度〉提取时间〉料液比;以80%乙醇与0.2mol/L柠檬酸混合溶液为提取剂,最佳工艺条件为提取温度60℃、提取时间2h、料液比1:10。%Purple corn pigment is extracted from purple corn,and its stability is studied.By single-factor test the effect of various process parameters on the purple corn pigment extraction rate is determined.Orthogonal experiment is designed selecting three factors,namely,the extraction temperature,extraction time,solid-liquid ratio.The purple corn pigment extraction process was optimized.The results show that the selected three factors affecting the size of purple corn pigment extraction rate of primary and secondary order:for the extraction temperature;extraction time;solid-liquid ratio,the optimum conditions were:80% ethanol and 0.2 mol /L citric acid mixture as the extracting agent,and the extraction temperature was 60 ℃,and the extraction time was 2 h and the ratio of material to solvent was 1:10.

  17. Relevance of LIF and EGF on Mouse Preimplantation Embryo Development

    Directory of Open Access Journals (Sweden)

    Iraj Amiri

    2008-01-01

    Full Text Available Objective: Recent evidence suggests that Leukemia Inhibitory Factor (LIF, a member ofinterleukin-6 family, has biological actions on preimplantation embryo development. Alsoit is established that Epidermal Growth Factor (EGF, a strong mitosis-promoting agent,improves the preimplantation embryo development by increasing the cell metabolism andproliferation. The purpose of the present study is to investigate the effects of these factors,alone and in combination together, on preimplantation and development of the embryo.Materials and Methods: Six to eight weeks old NMRI mice were super ovulated by injectionof 10IU PMSG and 10IU hCG, then the mated mice were killed 46 hours later. Theiroviducts were flushed, two-cell embryos collected and divided randomly to the four groupsas following: Control, treatment 1 (LIF, treatment 2 (EGF, treatment 3 (LIF+EGF. In eachgroup, the embryos were cultured in an incubator at 37°C with 5% CO2 and 90% humidityfor 72hrs. The state of embryo development was evaluated in 24,36,48,60 and 72hrsfollowing the embryos cultures. By the end of the cultures, cell apoptosis was studiedby the terminal deoxynucleotidyl transferas-mediated dUTP nick end-labeling (TUNELtechnique.Results: Significant difference was detected in the rate of hatching in the LIF and LIF+EGFgroups. This difference was also seen in the rate of blastocyst formation after 36hrs(p<0.05 and in the average of the total cell number (p<0.05 after 72hrs. In comparison tothe apoptotic index, there was no significant difference between the control and treatmentgroups.Conclusion: The findings in this study show a beneficial effect of LIF and EGF on theblastocyst formation, hatching and its total cell numbers in vitro.

  18. Technology of preventing drilling hole collapse in soft coal seam by inserting casing in drill pipe%钻杆内下套管防治软煤层钻孔塌孔技术

    Institute of Scientific and Technical Information of China (English)

    李定启; 邓广涛; 李海贵; 王明中

    2015-01-01

    In order to prevent collapse and block of drilling hole in short time when conducting gas extraction in soft coal seam, and improve the gas drainage efficiency of drilling, the equipments and methods of inserting casing in drill pipe for soft coal seam were analyzed and studied.By comparing and analyzing the experimental results in soft coal seam with conventional technology of casing running, original technology of inserting casing in drill pipe and improved technology of inserting casing in drill pipe, it showed that:the length of inserting casing by the improved technology is much greater than that by conventional technology, and the design of drill bit and drilling rob on e-quipment of inserting casing in drill pipe have a greater influence on the drilling and length of inserting casing.In the design, the diameter of drilling bit should be moderate and the smooth joint connection should be adopted on drilling rob.The gas drainage capacity of drilling per hundred meters by this technology is much greater than that by ordinary technology.%为了防止软煤层钻孔在瓦斯抽采过程中短时间内塌孔堵死,提高钻孔瓦斯抽放效率,对软煤层钻孔钻杆内下套管设备和工艺方法进行了分析和研究。通过对比分析常规下套管方式、原有钻杆内下套管方式和改进后钻杆内下套管方式的在软煤层试验,得出以下结论:采用钻杆内下套管设备下套管的长度远大于采用常规钻进方式下套管的长度;钻杆内下套管设备的钻头和钻杆设计对钻进和下套管长度影响较大,设计时钻头直径大小应适中,钻杆应尽量采取内平丝扣连接;采用钻杆内下套管方式的百米钻孔瓦斯抽放量要远大于普通钻进下套管钻孔的百米钻孔瓦斯抽放量。

  19. 北京小龙门地区元宝枫的种群结构及点格局分析%Population Structure and Point Pattern of Acer truncatum Bunge in Xiaolongmen Reserve, Beijing

    Institute of Scientific and Technical Information of China (English)

    李玲慧; 毛伊幻

    2013-01-01

    The distribution pattern of plant populations is closely related to spatial scale.By traditional sampling method,only one-scale point pattern can be studied.By comparison,point pattern analysis method is based on spatial mapped points of individual distribution and can analyze patterns under all scales along a gradient.The results are more consistent to the reality,especially for population structure.By using point pattern analysis method,the distribution pattern of all age-classes of Acer truncatum in Xiaolongmen Reserve,Beijing and its relationship with that of other arbors were studied.The results show that the distribution of Acer truncatum Bunge in the sampling area is centralization distribution,and it varies from age class to age class.Other arbors have obvious (positive or negative) effects on the distribution of Acer truncatum.The relationship between Acer truncatum and JugIans mandshurica,Tilia cordata,Fraxinus americana L var juglandifolia Rehd is different.%植物群落的分布格局与空间尺度有着密切关系.在传统取样方法下,只能研究一种尺度下的格局,与之相比点格局分析法是以种群个体空间分布的坐标点图为基础,通过单一的分布情况分析各种尺度下的格局.该文通过点格局分析对北京小龙门地区元宝枫分布格局、各龄级的分布格局以及其与其他乔木的相关关系进行了研究.结果表明:元宝枫在样地内呈明显的集群分布,各龄级密度差异显著.幼龄级在小尺度下集群分布,大尺度下随机分布;随着龄级的增长,种群显著地趋于随机分布.核桃楸是该群落的优势种,且元宝枫和核桃楸、大叶白蜡、小叶椴之间在不同尺度下相关关系不同.

  20. 复合酶法提取鸡腿菇多糖的工艺优化%Optimization of Extraction of Polysaccharides from Coprinus comatus by Composite Enzyme method

    Institute of Scientific and Technical Information of China (English)

    郑义; 李超; 王卫东; 王乃馨; 王健龙; 张雷; 尹蓬

    2011-01-01

    The optimum processing conditions of the enzymatic extraction of polysaccharides from Coprinus comatus were studied.By using papain and cellulase complex processing method,the effects of liquid-to-solid ratio,the amount of composite enzyme adding,mass ratio of papain to cellulase,enzymolysis time,enzymolysis pH value,extraction time on the yield of polysaccharides were investigated by the single factor experiments.Technology parameters were optimized by Box–Behnken statistical design,then regression mathematical model was established,the model fitted significantly well and the optimum combination was obtained.When the extraction parameters were controlled at enzymolysis temperature 51.4 ℃,enzymolysis pH value 5.2 and mass ratio of papain to cellulase 0.86,the polysaccharides yield could be up to 6.42%.%为优化鸡腿菇多糖的提取工艺,采用木瓜蛋白酶与纤维素酶复合处理,通过单因素试验研究了液料比、复合酶添加量、木瓜蛋白酶与纤维素酶质量比、酶解温度、pH值和提取时间对鸡腿菇多糖得率的影响。在单因素试验的基础上,采用Box-Benhnken中心组合试验设计,建立了具有较好预测性能的鸡腿菇多糖提取条件的回归模型,获得了复合酶法提取鸡腿菇多糖的最佳工艺,即酶解温度51.4℃、酶解pH值5.2、木瓜蛋白酶与纤维素酶质量比0.86,在此条件下鸡腿菇多糖得率可达6.42%。

  1. 基于Witness的飞轮生产线生产节拍平衡研究%Research on takt time balance of flywheel production line based on witness software

    Institute of Scientific and Technical Information of China (English)

    贾秋红; 肖燕; 龚玉洁; 周康渠; 敖希琴

    2011-01-01

    The takt time balance of workshop production determines the level of production efficiency,which is the best way to solve the main problems facing with the manufacturing workshop.First the balance problems of takt time of a flywheel production line are studied.By analyzing the production status of some flywheel production line and measuring the process operating time ,the simulation model is constructed using the Witness software. Then the bottleneck processes of production line and utilization inadequate are found by simulating modelingAnd the production line is improved by using tskt time balancing method, which achieves the target and makes the bottleneck processes be eliminated with the utilization rate of machine and personnel being balanced.Through comparing the relevant parameters before and after the balance, the improvement results of production line are found to be significant and the production efficiency is improved,thus the production costs are reduced.%车间的生产节拍平衡决定了企业生产效率的高低,是解决制造业车间面临的主要问题的最佳途径,研究了某飞轮生产线生产节拍的平衡问题.对某飞轮生产线生产现状进行分析,测定工序作业时间,应用Witness软件进行仿真建模,发现瓶颈环节与利用率不足等不平衡现象,运用生产节拍平衡方法等改进生产线,达到日产目标,消除瓶颈环节,使机器与人员利用率均衡.通过比较生产节拍平衡前后的相关参数,生产线改善效果明显,生产效率得以提高,进而降低企业成本.

  2. Effects of simulated acid rain on leaf litter decomposition of Ginkgo biloba and Taxodium ascendens%模拟酸雨胁迫对银杏与池杉凋落叶分解的影响

    Institute of Scientific and Technical Information of China (English)

    叶龙华; 孙小川; 宋曰钦; 薛立

    2015-01-01

    以硫酸、亚硫酸为原料配制不同 pH 值的酸溶液,采用分解袋法,在室内模拟酸雨处理银杏和池杉凋落叶,研究模拟酸雨胁迫对银杏和池杉凋落叶分解的影响。结果表明:不同 pH 值的模拟酸雨胁迫对银杏和池杉凋落叶的分解率均存在一定的抑制作用,以对照组(pH 值7.0)的凋落叶分解率最高,其次是轻度(pH 值5.6)酸雨胁迫和中度(pH 值4.0)酸雨胁迫处理的,分解率最低的是重度(pH 值2.5)酸雨胁迫处理的,表现为随酸雨胁迫强度增强即 pH 值的减小而减小的趋势。2个不同树种的凋落叶对酸雨胁迫的反应也存在差异,池杉落叶分解受酸雨的影响比银杏落叶的小。%In order to probe the growing problem of acid rain on leaf litter decomposition,the effects of simulated acid rain on leaf litter decomposition of Ginkgo biloba and Taxodium ascendens were studiedby litterbag method in laboratory conditions.The leaf litters of G.biloba and T.ascendens were treated by different pH value of simulated acid rain.The re-sult indecated that the leaf litter decomposition rates of G.biloba and T.ascendens increased with decreasing acid rain in-tensity.The leaf litter decomposition rate of both species was the fastest in the control (pH7.0),followed by mild acid stress (pH5.6),moderate acid rain (pH4.0)and the severe acid rain (pH2.5).There was a difference in respond of leaf litter decomposition of the two species to acid rain.Acid rain influenced on leaf litter decomposition of T.ascendens was smaller than G.biloba.

  3. Analysis on ultrasonic phased array inspection imaging quality for train wheel rim%列车轮辋超声相控阵成像质量分析

    Institute of Scientific and Technical Information of China (English)

    胡宏伟; 王哲; 刘希玲; 王向红

    2015-01-01

    To solve the problem of low image quality and defect identification difficulty when using ultrasonic phased array to inspect train wheel rim,the sound pressure characteristics of phased array transducer were ana-lyzed.Besides,the suitable detection depth was obtained as well.The effects of the rim contact surface and cou-pling status for the image quality were analyzed.An ultrasonic phased array inspection experiment was carried out on a wheel rim test block.Taking a horizontal hole and a slot as defect examples,the echo amplitude chan-ging characteristic and image quality were studied.By comparing with flat block analysis,the main factors and influencing rule for ultrasonic phased array imaging quality were obtained.The study provides a reference to im-prove the ultrasonic phased array inspection process and the accuracy of defect detection for rim.%为解决超声相控阵检测列车轮辋易出现的成像质量低和缺陷识别困难等问题,分析相控阵换能器声压特性,获取合适的缺陷检测深度,讨论轮辋界面及耦合情况对成像质量的影响,开展轮辋试块相控阵检测实验。以水平孔和管穿槽缺陷为例,研究不同深度缺陷的回波幅值变化特点及成像质量,并通过与平面试块对比分析,获得轮辋相控阵成像质量的主要影响因素和影响规律,为改进轮辋超声相控阵检测工艺和提高缺陷检测精度提供参考。

  4. Application of a high cholesterol-reducing Lactobacillus acidophilus strain in fermented milk%一株高效降胆固醇嗜酸乳杆菌在发酵乳中的应用

    Institute of Scientific and Technical Information of China (English)

    田建军; 张开屏; 张保军; 靳烨

    2012-01-01

    采用高效降胆固醇嗜酸乳杆菌菌株2-2和嗜热链球菌调制发酵剂B,研究了发酵剂B在发酵乳中的应用。通过与传统保加利亚乳杆菌和嗜热链球菌调制的发酵剂A的对比,结果表明,发酵剂B有较强的胆固醇去除效力和弱的后酸化能力。4℃条件下存放15d后发酵乳的酸度为103.6°T,发酵乳中乳酸菌活菌数为2.6×107cfu/mL,高于标准的最低限制(≥106cfu/mL)。研究表明,在降胆固醇和抑制后酸化意义上,发酵剂B能够取代发酵剂A。%The starter culture B was formulated with strain 2-2 of high cholesterol-reducing Lactobacillus acidophilus and Streptococcus thermophilus.Then the application of starter culture B in fermented milk production was studied.By comparison of starter culture B with A that formulaed traditionally with Lactobacillus bulgaricus and Streptococcus thermophilus,the results indicated that the starter culture B had abilities of strong cholesterol-reducing and weak post-acidification.After 15d storage at 4℃,the acidity of the fermented milk was 103.6°T and the number of living bacteria was 2.6×107cfu/mL,it was much larger than the minimum standard(≥106cfu/mL).The study indicated that the starter culture A could be replaced by B in a sense of reducing cholesterol and inhibiting the extent of post-acidification.

  5. Ultrastructure and elemental composition of the eggshell of Reeve's Pheasant (Syrmaticus reevesii)

    Institute of Scientific and Technical Information of China (English)

    CHANG Chongyan; ZHANG Zhengwang; CHEN Xiaoduan; LIU Jinying; SUN Quanhui

    2007-01-01

    The eggshell of Reeve's pheasant (Syrmaticus reevesii) collected from the Dongzhai National Nature Reserve in Henan Province,China was studied.By using scanning electron microscopy and inductively coupled plasma (ICP) spectrometry,the ultrastructure and elemental composition of the eggshell was determined.The study showed that the average thickness of the surface layer of crystals,the palisade and cone layer,and the eggshell membrane were 20.8,220.8 and 62.5 larn,respectively,accounting for 6.8%,72.6% and 20.6% of the total thickness of the eggshell.There were many vesicular holes in the palisade layer with an average diameter of 0.32±0.08 μm(n = 30).The function of these holes might be significant to air exchange.The shape of the eggshell pore on the surface layer of crystals is round or elliptical.The fracture surface of the pore is funnel-shaped.Some granules filled the upper part of the eggshell pores.The content of 21 elements in the eggshell of wild and captive Reeve's pheasants was compared and presented.It indicated that among the elements that made up the eggshell of the wild pheasant,the content of Ca,Mg,P and S was much higher,ω> 1 mg/g,with ω (Ca) being higher than 40% of the eggshell.The contents of Na,Si,Sr,K and A1 were ω = 0.1-1 mg/g,while Fe,Zn,Pb,Mn,Cu,V and Ti had lower concentrations (ω = 1-100 μg/g).The ω ofNi,Cr,Co,Se,Cd were lower than 1 μg/g.The elemental composition in the eggshell of the captive Reeve's pheasant kept in the Dongzhai National Natural Reserve was significantly different from that of the wild species,with a difference of over 20% on S,Cu,Fe,AI,Mn,Si,Sr,Se and Cr.The lower intake of Fe,Mn,Si and Sr on the one hand and the higher intake of S,Cu,Al and Cr on the other hand might be responsible for the low fertility of captive Reeve's pheasants in the Dongzhai National Nature Reserve.In order to ensure that the pheasants are receiving the proper amount of nutrition and to improve their breeding success,the amount of

  6. Study on processing technology of lueyang black-bone chicken sausage%略阳乌鸡肉肠的加工工艺

    Institute of Scientific and Technical Information of China (English)

    陈锐

    2015-01-01

    The processing of chicken sausages prepared by Lueyang black-bone chicken meat was studied.By single factor and orthogonal test method,the sausages processing formula are optimum.The results showed that the pig fat and chicken meat proportion were 20∶ 80(g∶ g),starch 4%,salt 3%,composite spices 2%.Under the above conditions,the product sensory quality was the best.The pig fat and starch improved the quality,and the amount of salt and composite spices significantly improved the flavor.This process of black-bone chicken sausages has a bright color,compact homogenous texture,neatly slices,delicious taste and the very good nutritional value.%以略阳乌鸡肉为主要原料,研究了肉肠的加工工艺.通过单因素试验和正交试验对其肉肠的加工配方进行了探讨,确定了肉肠的最佳工艺及技术参数.结果表明:猪肥膘与略阳乌鸡肉比例20∶ 80(g∶ g)、淀粉添加量4%、食盐添加量3%、复合香辛料添加量2%时,产品感官品质达到最佳.猪肥膘和淀粉的添加使肉肠质地的改善起到了明显的效果,食盐和复合香辛料添加量的控制显著改善了肉肠的风味.通过此工艺加工的乌鸡肉肠色泽鲜亮,组织紧致均匀,切片整齐,口感细腻,滋味鲜美,具有很好的营养价值.

  7. Effects of Ultrasonic Action on Compression Performance of 6061 Aluminium Alloy%超声激励对6061铝合金压缩性能的影响

    Institute of Scientific and Technical Information of China (English)

    朱政强; 张义福

    2011-01-01

    金属成形过程中施加超声激励可显著减小金属成形力,提高金属的变形能力和加工质量。应力叠加、温度升高和接触界面摩擦条件的改变是成形力下降的主要因素。研究了下平板施加超声激励对6061铝合金压缩性能的影响。通过调整接触界面摩擦因数、超声振幅等主要加工参数,基于ABAQUS有限元软件的隐式积分算法模拟了单轴应力情况下施加超声振动对铝合金应力-应变关系的影响规律。结果表明,超声激励降低了工件和模具间的摩擦力并使得6061铝合金材料软化。%Ultrasonic action in metal forming processing can reduce the forming load significantly;improve metal deformability and processing quality.The main factors effecting the reduction of forming load are the stress superposition,temperature increases and the change in the friction condition of contact interface.The effects of ultrasonic action on the compression performance of 6061 aluminum alloy were studied.By adjusting the main process parameters,such as coefficient of friction at the contact interface and ultrasonic amplitude etc.and based on ABAQUS implicit integration algorithm,the investigation on the influence law of stress-strain relationship under superimposing ultrasonic vibrations by different parameters was processed.The study indicates that ultrasonic action can reduce the interfacial friction and soften 6061 aluminum material during ultrasonic compression.

  8. 拦截高速机动目标的动态终端滑模制导律设计%Guidance law based on dynamic terminal sliding mode for high speed and maneuvering target

    Institute of Scientific and Technical Information of China (English)

    雷虎民; 张旭; 李炯; 刘滔

    2015-01-01

    针对新型高速机动目标的拦截问题,提出了一种基于动态终端滑模控制理论的鲁棒制导律设计方案。首先,基于动态终端滑模控制的有限时间收敛特性,研究了一种带补偿因子的终端滑模切换函数;然后,将其通过微分环节构造了非线性动态滑模超平面;最后,设计了动态终端滑模制导律,并对其有限时间收敛特性进行了分析。该制导律不仅具有有限时间收敛特性,而且针对导弹指令加速度的导数进行设计,可将滑模控制中具有的不连续项转移到制导律的一阶导数当中去,有效消除了抖振。仿真结果表明,该制导律可使导弹视线角速率有限时间收敛,且具有更强的鲁棒性和更高的制导精度。%A design scheme of robust guidance law based on dynamic terminal sliding mode control was proposed for the inter-ception of new high speed and maneuvering targets. Firstly, based on the characteristics of finite time convergence of the dynamic terminal sling mode control, a terminal sliding mode switching function with compensating factor was studied,by which a non-linear sliding mode super-surface was proposed through differentiation element then. Finally, the guidance law based on dynamic terminal sliding mode was designed,and its characteristics of finite time convergence were analyzed. The new guidance law not only has the character of finite time convergence,but also is designed based on the derivative of the command acceleration,which could transfer the discrete term that is common in sliding mode control into the first-order derivatives of the guidance law,and remove the chatte-ring problems. Simulation results show that the proposed guidance law could guarantee the missile's line-of-sight finite time conver-gence and has better robustness and guidance precision.

  9. 坡道上重载列车纵向冲动研究%Influence of train brake on longitudinal impulse of a heavy haul train passing through a ramp

    Institute of Scientific and Technical Information of China (English)

    魏伟; 王强

    2014-01-01

    针对重载列车实际运用中在复杂纵断面紧急制动时导致列车纵向冲动过大的问题,应用空气制动系统和纵向动力学联合仿真系统,研究重载列车通过坡道时纵向冲动水平,以及坡道上列车制动起始位置、坡道坡度大小和列车制动波速等因素对列车纵向冲动的影响。结果表明列车完全处于同一坡道上坡或下坡制动时与平道时的冲动水平相当。列车在通过平道+上坡或下坡+平道时做紧急制动会产生较大的车钩力压力,1万吨编组列车第40车位于变坡点是最不利的制动起始位置。列车在变坡点的纵向冲动主要受到制动不同步性和坡道坡度两种因素影响,坡道坡度越小,列车的纵向冲动水平越小;提高制动波速能有效减小车钩力。%The excessive longitudinal impulse of heavy haul trains when an emergency brake was made on the trains was studied.By using a combined simulation system of air braking system and train longitudinal dynamic behavior,the longitudinal impulse level of heavy haul trains passing through a ramp was analyzed.The influences of the braking start position,ramp slope size and train braking velocity on the train longitudinal impulse were discussed.The results showed that when braking emergently the trains at uphill or downhill on a ramp,the impulse level is the same as that when it is on a flat track;coupler force is generated signifigantly when braking emergently the trains passing through complex route (such as,flat plus uphill or downhill plus flat);for a ten thousand tons train,the most dangerous braking position is the fortieth freight car of the train placing at the ramp slop change point;the brake synchronism and the slope of the ramp are the two main factors influencing the longitudinal impulse occuring at the ramp slope change point;the smaller the ramp slope,the smaller the train longitudinal impulse level;increasing brake synchronism reduces

  10. QSAR Study of Acute Toxicity of Substituted Benzene Compounds to Zebra Fish%取代苯类化合物对斑马鱼急性毒性的QSAR研究

    Institute of Scientific and Technical Information of China (English)

    刘洋; 范雪兰; 王志平; 李捍东

    2013-01-01

    On the basis of quantitative structure-activity relationship (QSAR)method,the internal effects between 26 substituted benzene compounds and zebra fish 48 h acute toxicity (-lgLC50) were quantitatively studied.By using AMI quantum chemistry calculation method,first the correlation between 8 typical quantum chemistry parameters with zebra fish 48 h-lgLC50 were calculated,then through the stepwise multiple linear regression (MLR) method,a QSAR model was established depicting the relationship between substituted benzene compounds and 48 h-lgLC50 on zebra fish,which were tested by internal and external validations,with the obtained multiple correlation coefficient 0.942.Finally using QSAR model to study the influence of substituted benzene compounds quantum chemistry parameters on zebra fish 48 h-lgLC50,and results indicated that the strongest correlation parameter with-lgLC50 is n-octanol-water partition coefficient (LogP),and the electronegativity is negatively correlated with-lgLC50.The obtained QSAR model showed good robustness and high predictive ability,which can be used to predict acute toxicity of substituted benzene compounds on zebra fish.%该文基于定量-构效关系(QSAR)原理,研究了26种取代苯类化合物与斑马鱼的48h急性毒性(-lgLC50)之间的内在定量关系.利用AM1量子化学计算方法,首先计算了8种典型量子化学参数与斑马鱼48 h-lgLC50的相关性;然后通过逐步多元线性回归(MLR)方法建立了取代苯类化合物对斑马鱼48h-lgLC50的QSAR模型,并对所建模型分别进行了内部验证和外部验证,所得复相关系数R2=0.942;最后利用QSAR模型,分析了取代苯类化合物量子化学参数对斑马鱼48 h-lgLC50的影响.结果表明:正辛醇-水分配系数(LogP)与-lgLC50的相关性最大,负电性[-(L+H)/2]与-lgLC50负相关.所得QSAR模型具有较高的稳定性及预测能力,可以用来预测取代苯类化合物对斑马鱼的急性毒性.

  11. Research of upper surface roughness of metal parts fabricated by selective laser melting%选区激光熔化成型金属零件上表面粗糙度的研究

    Institute of Scientific and Technical Information of China (English)

    刘睿诚; 杨永强; 王迪

    2013-01-01

    In order to provide the theory basis to improve the surface quality , the main factors affecting the upper surface roughness of metal parts fabricated by selective laser melting (SLM) were studied.By studying the single track melting, the upper surface roughness of SLM parts was analyzed from the view of melting track lapping .The metal parts were fabricated by using the self-developed fabrication equipment Dimetal-280 and the measure roughness parameters were compared with the theoretical value.The theoretical value of arithmetical mean deviation of the profile Ra was 3.21μm and the theoretical value of ten-point height of irregulartlies Rz was 12.79μm.The actual value was Ra =7.36μm and Rz =40.01μm.After electrochemical polishing, the surface roughness was reduced to Ra =2.34μm and Rz =10.86μm.The results prove that upper surface roughness of the metal part was influenced by melting track width , scanning space and layer thickness altogether.The reason of the discrepancy between theoretical value and actual value was some defects such as instability in melting track, spheroidization on the surface and dust adhesiveness .The quality of surface roughness was greatly improved after electrochemical polishing .The metal parts processed by selective laser melting could obtain satisfied surface roughness in this experiment .The results provide guidance to surface research and industrial application in the future.%  为了改善成型件表面质量,从微观上研究了决定选区激光熔化成型金属零件的上表面粗糙度的主要因素,通过研究单熔道成型,从熔道搭接的角度理论分析了成型件的上表面粗糙度,基于自主研发的成型设备Dimet-al-280加工实体零件进行了实际测量对比,获得表面粗糙度的轮廓算术平均偏差Ra 的理论值为3.21μm,微观不平度十点高度Rz 的理论值为12.79μm,其实测值Ra =7.36μm,Rz =40.01μm;进行喷砂和电解抛光处理后,

  12. 不平顺路面的车辆动载诱发饱和地基的动应力响应%Influences of vehicle dynamic load on dynamic stress in saturated poro-elastic ground

    Institute of Scientific and Technical Information of China (English)

    周仁义; 钱建固; 黄茂松

    2016-01-01

    对由于不平顺路面引起的车辆附加动荷载在饱和多孔地基中的动应力开展了解析理论研究。通过承受移动矩形垂直荷载的三维饱和多孔地基的基本解,采用矩阵递推法得到多层饱和半空间解,数值积分得到数值结果。将该方法运用于具有不平顺路面的饱和多孔半空间的情况,得到了附加动荷载在饱和多孔地基中所产生的动应力。计算结果分析了分层地基半空间计算模型的优点,还发现土体的软硬程度对地基动应力极为重要。附加动荷载的速度频率同步效应在地基中作用明显,尤其对于所产生的剪应力,在具有较硬较厚路面的情况下,附加动荷载所产生的剪应力的最大值已经超过自重恒载所产生的剪应力。不平顺波长对动应力也有很大影响,尤其是短波不平顺。在高速移动的四轮车辆荷载的情况下,不平顺的路面会造成地基的剧烈振动,不平顺波长越短(即路面越不平整),振动的越剧烈。%Here,the influences of dynamic component of vehicle load (caused by pavement roughness)on the dynamic stress responses in poroelastic ground were studied.By introducing an analytical solution to the three-dimensional dynamic stress in a saturated poroelastic half space subjected to a harmonic rectangular moving load,the solutions to a multi-layered saturated poroelastic half space under moving loading were derived using the transfer matrix method. Numerical results were obtained by performing inverse Fourier transformation.In the case of rough road in a saturated poroelastic half space,the numerical results were obtained and used to analyze the influences of the dynamic component of vehicle load (caused by pavement roughness)on the dynamic stress responses in the half space.The results showed that the advantages of the multi-layered poroelastic half space computing model and the stiffness of soil are important to the dynamic

  13. Seismic parameters of single-layer buckling-restrained braced frame%单层屈曲约束支撑框架的抗震参数

    Institute of Scientific and Technical Information of China (English)

    冯玉龙; 吴京; 孟少平; 付康

    2015-01-01

    To provide the design reference for the frame structure with buckling-restrained brace ( BRB) , the seismic parameters of the single-layer buckling-restrained braced frame ( BRBF) struc-ture are studied.By lateral displacement analysis, three key parameters characterizing the structural force and deformation, the BRB-to-frame stiffness ratio, the BRB-to-frame yield strength ratio and the beam-to-column line stiffness ratio, are derived.By taking the maximum displacement and the residual displacement under the specific ground motion as the evaluation indexes, parametric analyses are carried out.The analysis results show that when the BRB-to-frame stiffness ratio and the beam-to-column line stiffness ratio are small, both kinds of displacements decrease with the increase of the ratios.The BRB-to-frame yield strength ratio influences greatly on the structural yield displacement and mechanism.The reasonable values of the BRB-to-frame stiffness ratio, the BRB-to-frame yield strength ratio and the beam-to-column line stiffness ratio are 2, 0.7 and 0.45~5.00, respectively. Base on these reasonable values, two examples are designed and the corresponding seismic perform-ance is analyzed.The results show that the BRB-beam-column yield mechanism is formed in the structures.After the BRB yields, the ratio of the shear forces of the frame increases gradually.The layout principle of BRB has almost no obvious influence on the roof displacement response, but af-fects significantly the axial force of the adjacent columns.%为了给屈曲约束支撑框架设计提供参考,对单层屈曲约束支撑框架的抗震参数进行了研究.通过结构侧移分析,推导出表征该结构体系受力和变形特性的3个关键参数:支撑框架刚度比、支撑框架屈服强度比和梁柱线刚度比.以特定地震动下结构最大位移和残余位移作为评价指标,对结构进行了参数化分析.分析结果表明:当支撑框架刚度比和梁柱线刚

  14. Study on the Regeneration Effects of NGF on Destructive Superior Cervical Ganglia of Newborn Mice and Peroneal Nerve of Adult Rats%神经生长因子对小鼠颈上神经节和大鼠腓神经损伤后修复的影响

    Institute of Scientific and Technical Information of China (English)

    陈红; 佘振珏; 童夙明; 褚云鸿

    2001-01-01

    Purpose The regeneration effects of nerve growth factor(NGF)on superior cervical ganglia innewborn mice destroyed by vincristine(VCR)and peroneal nerve of adult rats destroyed by grip were studiedby morphological methods. Methods Superior cervical ganglia. The Qunming newborn mice at 2 dayswere divided into 3 groups: experiment, control and blank. The experiment animals were injected with VCR,10 μl/g of body weight at a concentration of 0.02 mmol/L. Simultaneously, the NGF was injected 2,5,10μg/g of body weight, respectively. But the control animals were only injected with VCR at the same dose.The blank control animals weren' t treated anything. All of these chemicals were injected once a day for 4days. 24h after the last injection, the superior cervical ganglia were dissected out and analyzed their size andmorphology. Peripheral nerve. The peroneal nerve of SD adult rats were destroyed by grip, and divided into2 groups: experiment and control. The experiment rats were injected with NGF 2,4 and 8 μg/kg of bodyweight respectively, near the gripped nerve,once a day for 12 days after 24 h of the injury. 24 h after the lastinjection, the perone al nerve and extensor longus digitorum were dissected out and analyzed their morphologyand counted the number of nerve fiber at proximal and distal injury. Results VCR injection in newbommice produced severe atrophy of superior cervical ganglia. And the neuronal cells apoptosed and decomposed.Simultaneous injections of NGF prevented the noxious effects of VCR, and resulted in an increase intransverse diameter from 61 to 95 percent and the total number of neuronal cells from 59 to 70 percent. Thisimproved degree was related to the dose of NGF. Furthermore, NGF obviously improved the structure of peroneal nerve and extensor longus digitorum. And this effect was the best in the high dosage. ConclusionsNerve growth factor has an obvious regeneration effects in superior cervical ganglia of newborn mice destroyed by VCR and

  15. Investigações sobre doenças de Psittacideos

    Directory of Open Access Journals (Sweden)

    Genesio Pacheco

    1932-08-01

    to be different from that of the virus of psittacosis studiedby him. We are very much obliged to him for the attention he paid to this verification. Virus of psittacosis - Infectiousness: man, monkey, rabbit, mouse, hen, canary. Neurotropic affinity. Inclusions: small, protoplasmic. Exsiccation: the virus has good power of preservation. Symptoms: inactivity, drowsiness, frequent diarrhoea, oculo-nasal discharge and cough, coma. Duration: 4 to 5 days. Bodily lesions: congestion of intestines, splenomegaly. Virus of S. Paulo - Infects only psittacidae, particularly those of the genus Amazona. No localization in the nervous system. Large, nuclear. Is rapidly destroyed. Inactivity, inappetency, adynamia (drooping of the wings, indifference, leaning its beak against the bars of the cage in order not to fall down; profuse diarrhoea, of whitish stools, at times enterorrhagia; prolonged coma. 2 to 8 days. Foci of yellowish necrosis in liver, spleen and lung. At times, congestion of intestines. Characteristic features common to the two viruses.-They act in great dilutions, filter through tight candles though being partly retained, are preserved under glycerine or Bedson's solution, are stable at 55°C. heat and are destroyed by physical and chemical agents. Both virus diseases are very seldom met with in psittacidae: only once, amongst numberless sick parrots, the author met with a disease of the virus differring from that of psittacosis. This disease, greatly transmissible to man, ought to be more frequent, if it were common in parrots. On the contrary, bacteria cause diseases in these animals with great frequency, presenting variable characters, from a severe epizootic form, rapidly mortal, to ambulatory or silent forms, for the most part developing towards a cure or assuming a chronic character. Amongst the bacteria which cause the infection of this group the salmonellae predominate and amongst them the bacterium discovered by Nocard, as well as a species which in the