WorldWideScience

Sample records for a-ga010 studiedby spa-leed

  1. 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).

  2. 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.

  3. 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.

  4. Adsorption of PTCDA on GaN(0001) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Christian; Tessarek, Christian; Figge, Stephan; Flege, Jan Ingo; Schmidt, Thomas; Hommel, Detlef; Falta, Jens [Institute of Solid State Physics, University of Bremen, 28359 Bremen (Germany); Jaye, Cherno; Fischer, Daniel A. [Ceramics Division, National Institute of Standards and Technology, Gaithersburg, MD (United States)

    2010-07-01

    Ordered growth of thin PTCDA layers is mainly observed on metals but recent reports have shown that some molecules also show ordered layers on unpassivated III-V semiconductor surfaces. In this work we investigate the adsorption of PTCDA on gallium-polar GaN(0001) with different methods. X-ray photoelectron spectroscopy (XPS) shows that the molecules are not dissociating after deposition, because the peak area ratios (including the shake-up's) for the perylene to carboxylic C1s feature is near the expected ratio for the intact molecule. Scanning tunneling microscopy (STM) and spot profile analyzing low energy electron diffraction (SPA-LEED) measurements reveal an island growth mode. For monolayer equivalent deposits, the near edge X-ray absorption fine structure (NEAFS) data of the C K-edge exhibit no polarization dependence indicating a disordered mixture of molecules in upstanding and down-lying geometry. However, for multilayer equivalent deposits a polarization dependence is observed which suggests a flat-lying geometry of the molecules. These findings are in good agreement with high-resolution STM and SPA-LEED data which reveal lateral ordering, compatible with a bulk-like configuration, within the islands.

  5. 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.)

  6. 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.

  7. 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

  8. Uenbinding'' an adsorbed organic molecule: K plus PTCDA on Ag(110)

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Oliver; Schmitz, Christoph H.; Fiedler, Benjamin; Sokolowski, Moritz [Institut fuer Physikalische und Theoretische Chemie, Universitaet Bonn (Germany); Mercurio, Giuseppe; Subach, Sergey; Tautz, Frank Stefan [Institut fuer Bio- und Nanosysteme 3, Forschungszentrum Juelich (Germany)

    2010-07-01

    We have doped the well-known brick-wall structure of pristine PTCDA which is present in the monolayer on the Ag(110) surface with potassium (K) and investigated the induced structural and electronic changes at the interface. SPA-LEED measurements reveal that the structural order of the PTCDA molecules is strongly altered upon K dosing: A variety of co-existing binary phases is observed within the monolayer. In addition we have conducted XPS and NIXSW measurements on K+PTCDA/Ag(110). The photoemission experiments indicate that the K atoms preferentially interact with the carboxylic groups of the co-adsorbed PTCDA molecules. This interpretation is further supported by the NIXSW results: The adsorption geometries of the carboxylic and the anhydride oxygen (O) atoms are highly influenced by the presence of K on the surface, the bonding distances are extended. The adsorption height of the perylene core is also increased by K doping. Hence we conclude that the local Ag-O bonds at the interface are partially lifted by the co-adsorbed K and that K and Ag atoms compete for the interaction with the carboxylic groups of PTCDA while the bonding across the interface is weakened.

  9. 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.

  10. Surface stress and its consequences: In-situ study of PTCDA induced faceting of vicinal Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Pollinger, Florian; Vrdoljak, Pavo; Schmitt, Stefan; Kumpf, Christian; Schoell, Achim [Universitaet Wuerzburg, Experimentelle Physik II, Wuerzburg (Germany); Tian, Zhen; Sander, Dirk; Kirschner, Juergen [Max-Planck-Institut fuer Mikrostrukturphysik, Halle (Germany); Umbach, Eberhard [Universitaet Wuerzburg, Experimentelle Physik II, Wuerzburg (Germany); Forschungszentrum Karlsruhe (Germany)

    2008-07-01

    Adsorption of organic molecules on vicinal metal surfaces is known to promote faceting and self-organized ordering on mesoscopic scales. The adsorption of PTCDA on vicinal Ag(111) surfaces leads to grating-like structures after annealing. The system PTCDA/Ag(10 8 7) was investigated using two complementary techniques: An optical cantilever bending technique sensitive to changes in surface stress and spot-profile analysis low energy electron diffraction (SPA-LEED) to monitor the development of the interface structure during faceting. The data was compared to the related, non-faceting system PTCDA on Ag(111). Overall, we find a surface stress change of 0.7 N/m due to the PTCDA-induced faceting, whereas the adsorption of PTCDA without faceting induces a change of 0.4 N/m. Moreover, the data allows an explicit and unambiguous correlation of the surface stress change to the structural and morphological evolution of the interface during the adsorption of the PTCDA adlayer. In conclusion, the results provide experimental evidence for significant surface stress induced by an organic adsorbate and for its importance for faceting and long-range ordering at metal-organic interfaces.

  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. Studies of Dirac and Weyl fermions by angle resolved photoemission spectroscopy

    Science.gov (United States)

    Huang, Lunan

    This dissertation consists of three parts. First, we study magnetic domains in Nd2Fe14 B single crystals using high resolution magnetic force microscopy (MFM). In addition to the elongated, wavy nano-domains reported by a previous MFM study, we found that the micrometer size, star-shaped fractal pattern is constructed of an elongated network of nano-domains about 20 nm in width, with resolution-limited domain walls thinner than 2 nm. Second, we studied extra Dirac cones of multilayer graphene on SiC surface by ARPES and SPA-LEED. We discovered extra Dirac cones on Fermi surface due to SiC 6 x 6 and graphene 6√3 x 6√3 coincidence lattice on both single-layer and three-layer graphene sheets. We interpreted the position and intensity of the Dirac cone replicas, based on the scattering vectors from LEED patterns. We found the positions of replica Dirac cones are determined mostly by the 6 x 6 SiC superlattice even graphene layers grown thicker. Finally, we studied the electronic structure of MoTe2 by ARPES and experimentally confirmed the prediction of type II Weyl state in this material. By combining the result of Density Functional Theory calculations and Berry curvature calculations with out experimental data, we identified Fermi arcs, track states and Weyl points, all features predicted to exist in a type II Weyl semimetal. This material is an excellent playground for studies of exotic Fermions.

  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. 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.

  15. OSCILLATION OF A SECOND-ORDER HALF-LINEAR NEUTRAL DAMPED DIFFERENTIAL EQUATION WITH TIME-DELAY

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    In this paper,the oscillation for a class of second-order half-linear neutral damped differential equation with time-delay is studied.By means of Yang-inequality,the generalized Riccati transformation and a certain function,some new sufficient conditions for the oscillation are given for all solutions to the equation.

  16. 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.

  17. 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.

  18. 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.

  19. Verification of the spin-weighted spheroidal equation in the case of s =1

    Institute of Scientific and Technical Information of China (English)

    Zhang Qing; Tian Gui-Hua; Sun Yue; Dong Kun

    2012-01-01

    The spin-weighted spheroidal equation in the case of s =1 is studied.By transforming the independent variables,we make it take the Schr(o)dinger-like form.This Schr(o)dinger-like equation is very interesting in itself.We investigate it by using super-symmetric quantum mechanics and obtain the ground eigenvalue and eigenfunction,which are consistent with the results previously obtained.

  20. 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.

  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. On the mean value problem of the Smarandache Ceil function%关于Smarandache Ceil函数的一类均值问题

    Institute of Scientific and Technical Information of China (English)

    吕二兵

    2013-01-01

    The mean value distribution problem of Smarandache Ceil function and product of prime divisor function U(n) is studied.By using the analytic methods,an asymptotic formula of (Sk (n)-U(n))2 is given,with k≥2,n is any natural number.%研究了Smarandache Ceil函数与素因子积函数U(n)的均方值的分布问题.利用解析方法给出了(Sk (n)-U(n))2的一个有趣的渐近公式,其中k≥2,n为自然数.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Crystalline and lattice matched Ba0.7Si0.3O layers on plane and vicinal Si(001) surfaces

    International Nuclear Information System (INIS)

    In this work the low temperature growth conditions of epitaxial and lattice-matched Ba0.7Sr0.3O layers on Si(100) were investigated using the combination of low energy electron diffraction (LEED), x-ray photoemission (XPS) and electron energy loss spectroscopy (EELS). With these methods crystallinity, stoichiometry and electronic structure of both occupied and unoccupied levels were studied as a function of layer thickness. Oxide layers were generated by evaporating the metals in oxygen ambient pressure with the sample at room temperature. Perfect crystallinity and lattice matching was only obtained starting with a preadsorbed monolayer (ML) of Sr or Ba at a concentration close to one monolayer. The XPS analysis shows that Ba0.7Sr0.3O as a high-K gate dielectric offers an adequate band gap, an appropriate band alignment and a atomically sharp interface to the Si(001) substrate. No silicide and silicate species, or SiO2 formation at the interface after oxidation were found. To show that Ba0.7Sr0.3O is really appropriate to replace SiO2 as a gate dielectric, first C-V and I-V curves of MOS-diodes with SrO, BaO and Ba0.7Sr0.3O as gateoxide were measured under ambient conditions. Besides other results, it turns out that the measured dielectric constant of Ba0.7Sr0.3O conforms with the expected value of ε ∼ 25 - 30. Exploring ways for self-organized structuring of insulating films, the possibility to produce replicas of step trains, given by a vicinal Si(001)-4 [110] surface, in layers of crystalline and perfectly lattice matched Ba0.7Sr0.3O were investigated. For this purpose high-resolution spot profile analyses in low-energy electron diffraction (SPA-LEED) both on flat Si(001) and on vicinal Si(001)-4 [110] were carried out. The G(S) analysis of these mixed oxide layers reveals a strong influence of local compositional fluctuations of Sr and Ba ions and their respective scattering phases, which appears as an unphysically large variation of layer distances

  16. 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。

  17. Preliminary study on effect of jiaozi mixed with yeast on industrialized steamed bread%酵子与酵母混合对工业化发酵馒头影响的初步研究

    Institute of Scientific and Technical Information of China (English)

    梁一桢; 刘长虹; 李志建; 张婧雯; 黄闪闪

    2012-01-01

    研究了酵子与酵母经不同比例混合后评价指标的变化,包括糖化力、发酵力、酯化力及霉菌含量。结果显示,当发酵剂的混合比例在1∶4时表现最好。%The change of evaluation indicators after jiaozi mix with yeast at different proportion was studied.By measuring saccharification ability,fermentation ability,esterification ability and mold content under different proportion.The result showed that it performance well when the mixing ratio at 1:4.

  18. 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.

  19. Properties of radicals created by γ-ray irradiation of silk fabrics

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The properties of radicals from γ-ray irradiated silk fabrics were studiedby electron spin resonance method (ESR). The ESR spectra of silk fabrics irradiated inN2 showed a doublet at room temperature. The doublet became a singlet at g=2.0057after placing the sample in air for 24 hours. This can be explained by formation ofperoxide radicals. The radical concentration of the irradiated silk fabric and the decayrate of radicals are significantly affected by irradiation conditions, which include theabsorbed dose, atmosphere, and water content of the silk fabric samples. However, nodose rate effect on the radical concentration was observed. The results are of help in ourpractice of property modification of silk products by radiation graft copolymerization.``

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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。

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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。

  14. 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.

  15. 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.

  16. 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.

  17. RESEARCH ON RELATION OF TIME-EFFECT WITH PARTS’CURL DISTORTION IN STEREOLITHOGRAPHY%激光快速成形中时间效应与零件翘曲性关系研究

    Institute of Scientific and Technical Information of China (English)

    段玉岗; 王素琴; 李涤尘; 吴懋亮; 卢秉恒

    2001-01-01

    Solidification process and phenomenon of solidyfication shrinkage lagging polymerization are studied in SL,time-effect conception is put forward and the effect of shrinkage time-effect on parts'curl distortion and several embodiment are studied.By manufacturing parts,the theory put forward is validated.Improving manufacture process based on time-effect is used to minish the curl distortion of parts,the result shows the curl distortion is improved greatly.%研究了激光快速成形中树脂固化过程以及固化收缩滞后于聚合速度的现象,提出了收缩完成的时间效应概念,通过实物原形制作研究了时间效应对零件翘曲的影响及几种表现,并利用时间效应对成形工艺进行了改进,使零件翘曲性得到很大的改善。

  18. 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.

  19. 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.

  20. 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.

  1. The dynamics of one-dimensional random quantum X Y system with Dzyaloshinskii-Moriya interaction

    Institute of Scientific and Technical Information of China (English)

    Li Yin-Fang; Kong Xiang-Mu

    2013-01-01

    In this paper,the effects of random variables on the dynamics of the s =1/2 XY model with the Dzyaloshinskii-Moriya interaction are studied.By means of the recurrence relation method in the high-temperature limit,we calculate the spin autocorrelation functions as well as the corresponding spectral densities for the cases that the exchange couplings between spins or external magnetic fields satisfy the double-Gaussian distribution.It is found that when the standard deviation of random exchange coupling δJ (or the standard deviation of random external field δB) is small,the dynamics of the system undergoes a crossover from a collective-mode behavior to a central-peak one.However,when δJ (or δB) is large,the crossover vanishes,and the system shows a central-peak behavior or the most disordered one.We also analyze the cases in which the exchange couplings or the external fields satisfy the bimodal and the Gaussian distributions.Our results show that for all the cases considered,the dynamics of the above system is similar to that of the one-dimensional random XY model.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. The Technology of Extending the Existing Tunnels to Construct Harbin Metro%哈尔滨地铁利用既有隧道扩挖区间技术

    Institute of Scientific and Technical Information of China (English)

    刘效永

    2012-01-01

    哈尔滨地铁西大桥—教化广场区间和教化广场—铁路局区间建设为利用既有人防工程进行扩挖改建,属国内首例。针对既有隧道破除的结构安全性问题,通过对其首破及破除后结构内力变化的研究,选择适宜的首破点和破除方向,采用临时竖撑预支加固、先侧墙后仰拱、径向注浆和跳槽扩挖等施工方法和措施,使既有结构内力变化在可控范围内,有效地控制了拱顶沉降、仰拱上浮和地层位移,保障了结构安全和施工安全,确保了工程的顺利进展。%Harbin Metro from West Bridge to Jiaohua Square and Jiaohua Square to the railway bureau is constructed by extending the existing civil air defense engineering.Aiming at its structural-broken security problems,the structure internal force variations for first breaking and after breaking are studied.By means of appropriately selecting the first-breaking point and breaking direction,interim vertical pre-support enforcing from sidewall to arch invert as well as vertical grouting and interval digging expanding,the structure internal force variations are within controllable range,and the vault settlement,arch invert floating and ground movement are effectively controlled.The structure and constructing security and the smooth project process are ensured.

  7. 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.

  8. 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.

  9. 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。

  10. 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.

  11. 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.

  12. Output Pulse Envelope Analysis Based on the GaAs FET Pulse Power Amplifier%GaAs FET脉冲功率放大器输出脉冲包络分析研究

    Institute of Scientific and Technical Information of China (English)

    顾占彪; 王淼

    2013-01-01

    Based on the GaAs field effect transistor (FET) in the microwave pulse solid state power amplifier,the pulse waveform drop and overshooting were studied.By analyzing the causes of the pulse droop theoretically from pulse modulation circuit,the saturation depth of the GaAs FET and the channel temperature,it is pointed that the pulse droop could be improved by three methods,such as choosing the suitable capacitor value,making GaAs FET operate in saturation and reducing the channel temperature.By analyzing the pulse overshoot from the pulse modulation and the parasitic inductance,some improved measures were given,such as reducing the parasitic inductance circuit and selecting the appropriate quiescent operating point.These measures have been proved effectively by actual measurement from comparison of the data before and after the improvement for the pulse drop and pulse overshooting.%基于GaAs场效应晶体管(FET)微波脉冲固态功率放大器的输出脉冲包络,对输出脉冲波形的顶部降落与顶部过冲开展研究.从脉冲调制电路、GaAs FET的饱和深度以及沟道温度三个方面对脉冲顶降进行了讨论,指出了可以通过选用合适的储能电容、使GaAs FET工作在饱和状态、降低沟道温度来改善脉冲顶降.另外,从脉冲调制方式和寄生电感影响两方面分析了脉冲顶部过冲,给出了改善脉冲顶部过冲的措施,如减小电路中的寄生电感和选取合适的静态工作点.经实践验证,并通过脉冲顶降和顶部过冲在改善前后的数据对比,证明了上述措施是有效的.

  13. 辊式磁选机典型磁系结构磁场特性分析%Analysis on the Magnetic Field Characteristic of Roll Magnetic Separators with Different Magnetic System Structure

    Institute of Scientific and Technical Information of China (English)

    张义顺; 史长亮; 马娇; 王飞跃

    2013-01-01

    辊式磁选机对中强磁性矿物分选多为经验式分选,不同磁系磁场特性与对应磁选矿物基本物性(密度、比磁化率)间的相互关系并无探讨.基于MagNet软件模拟辊式磁选机单环磁系、四级拼接磁系(无轭铁)、八级拼接磁系(有/无轭铁)的磁力线及磁感应强度分布情况,得出各磁系磁场沿辊表周向变化趋势及磁感应强度随分选行程变化函数关系;考察了单元磁性颗粒在力平衡条件下其密度同比磁化率的比值与各磁系磁感应强度函数关系,综合分析得出不同磁系类型下矿物的分选标准.对辊式磁选机常用磁系磁场特性分析,为选择合适的辊式磁选机进行中强磁性矿物的高效分选提供基础理论指导.%Roll magnetic separators are blandly used to separate moderate and strong susceptibility minerals,but the correlation between the magnetic field characteristic of different magnetic system and the characteristics (density and per magnetic susceptibility) of minerals is rarely discussed.The paper simulated the magnetic field lines distribution and magnetic induction intensity of different magnetic system,including:single ring prototype,four-magnetic splicing poles prototype without yoke,eight-magnetic splicing poles prototype with and without yoke.The function between the magnetic induction intensity and separation distance was given.The function between ratios of the density and magnetic susceptibility of single magnetic particle,and the magnetic field strength of different magnetic system was studied.By comprehensive analysis,the minerals separation standard corresponding to magnetic system prototype was obtained.The magnetic field characteristics of roll magnetic separators with different magnetic system were analyzed,the results could provide basic theoretical guidance for the selection of a suitable roll magnetic separator to efficiently separate moderate and strong magnetic minerals.

  14. 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%。

  15. 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.

  16. 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。

  17. 基于语音控制的人机交互智能系统研究∗%Intelligent System Research based on Voice Control Human-computer Interaction

    Institute of Scientific and Technical Information of China (English)

    梁汉泉; 陈锦彪

    2015-01-01

    The voice control is one of the most promising emerging technologies,and it currently has been widely used in auto-motive terminals,intelligent robot,etc.The application of speech recognition in the toy car is studied.By DSP chips for voice con-trol system based on a highly integrated design,use the double silicon wheat noise reduction to achieve the audio data clearly.Based on DTW algorithm and dynamic template matching,the input speech in signal endpoint is detected,and someone's isolated word is recognized.When multiple semantic approximation vocabulary is failed to be correctly identified,provide selection processing,make the speech engine timbre and tone color different for the flexible processing,improve the recognition rate and the user experience. The speech recognition is tested in the normal life environment,and it can adapt to application in daily life or work environment. The results show that the scheme and algorithm has accurate recognition effect.%语音控制是当前最具发展前景的新兴技术之一,目前已广泛应用于车载终端、智能机器人等场合。对语音识别在玩具车上的应用进行了深入研究。基于高度集成的 DSP 芯片进行语音控制系统的设计,使用了双硅麦减噪,能够获取到清晰的音频数据。根据 DTW 算法和动态模板匹配,对输入语音信号进行了端点检测,对特定人的孤立词进行了识别。当多个语意近似词汇无法准确识别时,提供选择处理,使语音引擎对音质、音色的区别进行了灵活的处理,提高了识别率和用户体验感受。该语音识别在正常生活环境中进行了测试,能适应日常生活或工作环境。研究结果表明,此方案和算法具有准确的识别效果。

  18. 高能激光注入光纤导光锥耦合性能实验研究%Experimental Research on Coupling Technique of Optical Fiber for High Power Lasers

    Institute of Scientific and Technical Information of China (English)

    李岩; 王思雯

    2012-01-01

    A test method for the coupling efficiency of the taper fiber was presented.Using the taper fiber to transport laser was verified to be feasible by experiments.The coupling efficiencies of the taper fiber at different angles of 1°~5° and different states of rest and swing were studied.By analyzing the light guidance characteristics of the taper fiber,a design method for the optical fiber coupling system of the high-energy laser was presented.Research results show that the taper fiber can be used to realize light guidance of the high-energy laser beam under certain conditions,and the laser coupling transportation efficiency of the taper fiber is higher than 60% at the angle of 5°,and the threshold is more than 100 mJ.It is important to realize coupling light guidance of high-energy laser with a taper fiber for the internal field simulations of the opto-electrical countermeasure.%提出了测试光纤导光锥耦合效率的试验方法,通过试验验证了光纤导光锥实现激光传导的可行性,同时在光纤入射角度为1°~5°、运动状态为静止及甩动的条件下,对光纤导光锥的耦合效率进行了实验研究。研究结果表明,光纤导光锥在入射角为1°~5°、光斑直径约为2mm时的激光耦合传输效率大于60%,入射光损伤耐受力低于100mJ。利用光纤导光锥实现高能激光的耦合导光,对于开展光电对抗内场仿真试验具有重要意义。

  19. Computation of Vibration and Sound Radiation from Cylindrical Shells with Frame Coated by Damping Layer%含阻尼层基座的加筋柱壳振动及声辐射计算

    Institute of Scientific and Technical Information of China (English)

    谢天宇; 王永生; 付建; 魏应三; 王旅

    2013-01-01

    The influence on the vibration and sound radiation of submarine with frame coated by damping layer is systematically studied.By finite element analysis of constrained damping plate is presented and the nature frequencies match with theoretical ones well,which verifies the rationality of damping model.After that,the numerical of analysis of sound radiation from a submerged cylindrical stiffened shell have been carried out by using FEM and BEM,which approximately equals to the testing results.Taking constrained damping plates and cylindrical stiffened shells with frame as research objects,analysis of the influence on vibration character of frame and the underwater sound radiation noise of stiffened cylindrical shells whether the constrained damping layer covers on frame in it.The result shows with constrained damping layer the radiation noise of cylindrical shell and its frame will be reduced effectively.%为研究敷设阻尼材料基座对艇体振动辐射噪声的影响,采用有限元法计算得到约束阻尼板的固有频率同理论值吻合较好,验证了阻尼材料建模的合理性;并利用有限元/边界元法分析了加肋柱壳受激后的水下声辐射,结果同试验值基本一致;最后以加筋板(裸基座)和含基座的加肋圆柱壳作为对象,计算分析了约束阻尼对裸基座振动特性的影响以及基座敷设阻尼材料前后壳体辐射声场的变化.结果表明:敷设约束阻尼能有效降低加肋圆柱壳体及其内部基座的辐射噪声.

  20. 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

  1. Experiment on degradation of methane adsorption in coal by aerobic microorganism under low oxygen condition%低氧条件下好氧型微生物降解煤吸附甲烷实验

    Institute of Scientific and Technical Information of China (English)

    田坤云; 崔学锋; 张瑞林

    2016-01-01

    In order to study the degradation efficiency of aerobic microorganism on methane adsorption in coal under low oxy-gen environment condition, the aerobic methane oxidizing bacteria for degradation of methane with high efficiency was culti-vated, isolated and preliminary identified.An experimental analysis system on methane degradation under low oxygen envi-ronment was self-developed based on the methane adsorption and desorption device using high-pressure volumetric method, and the degradation efficiencies of methane oxidizing bacteria under the conditions of 0%, 5%and 15%oxygen concentra-tion were studied.By comparing the decrement of methane, increment of carbon dioxide and decrement of oxygen before and after experiment, it showed that in the range of oxygen concentration (0~15%) , with the increase of oxygen concentration and the duration of degradation time, the decrement of methane could reach 130.5 cm3 , the maximum increment of carbon dioxide could reach 25.7 cm3 , while 69 cm3 oxygen could be consumed at most.Under the condition of anaerobic environ-ment, the physiological activity of aerobic methane oxidizing bacteria was subject to certain restrictions, but the maximum degradation amount of methane could still reach 11.9 cm3 , and 3.5 cm3 carbon dioxide was produced.%为了研究好氧型微生物对低氧气浓度环境条件下煤吸附甲烷的降解效能,培养、分离、初步鉴定了高效降解甲烷的好氧型甲烷氧化菌。并在高压容量法瓦斯吸附-解吸装置的基础上,自主开发了低氧环境下甲烷降解实验分析系统,研究了氧气浓度为0%、5%和15%三种条件下甲烷氧化菌的降解效能,通过对实验前后甲烷减少量,二氧化碳增加量,氧气减少量进行分析。结果表明:在氧气浓度(0%~15%)范围内,随着氧气浓度升高及降解时间的持续,甲烷的减少量可达130.5 cm3,二氧化碳的增加量最高可达25.7 cm3,同时最多消耗69

  2. 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

  3. 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.

  4. 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,

  5. 单轴压缩下含预制孔洞板状花岗岩试样力学响应的试验和数值研究%EXPERIMENTAL AND NUMERICAL STUDIES OF MECHANICAL RESPONSE OF PLATE-SHAPE GRANITE SAMPLES CONTAINING PREFABRICATED HOLES UNDER UNIAXIAL COMPRESSION

    Institute of Scientific and Technical Information of China (English)

    李地元; 李夕兵; 李春林; 王毅远

    2011-01-01

    The uniaxial compression tests of plate-shape granite samples containing two prefabricated holes on each side, prepared from Iddefjord granite blocks in Norway, are carried out by Instron hydraulic servo control testing machine in laboratory. The axial stress, axial and lateral strain, acoustic emission(AE) counts and failure modes of the samples are monitored during the tests. The splitting cracks occur near the holes' vertical surface and parallel to the loading direction when the loading stress increases to a certain value. Some characteristics of rockburst phenomena such as rock block ejection and slabbing failure can be observed around the prefabricated holes under high compressive stress. The failure modes of samples always initiate from the splitting fractures around the holes under uniaxial compression. By observing the AE counts rate curve, it is shown that more jumping mutation points appear in the curve than that of intact rock samples. Based on the experimental studies, numerical models are validated by FLAC (3 dimensions fast lagrangian analysis of continua). The principal stresses distributions in the samples are obtained by the elastic model analysis, while the failure process is studiedby the Mohr-Coulomb strain softening model. The modes of failure zones are monitored and characterized by the AE count events. Most failure zones are failed in tension and connected together to form as splitting fractures parallel to the vertical boundary of the holes. The numerical results are almost the same as the laboratory tests. The research results, to some degree, reveal the formation mechanism of slabbing fractures, which are usually parallel to the excavation boundary surrounding underground openings in hard rocks under high in-situ stresses.%利用挪威Iddefjord花岗岩试样加工制备含双侧预制方形孔洞的板状试样,并在Instron液压伺服控制试验机上开展单轴压缩试验,监测试样的应力、应变、声发射信号特征及

  6. 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

  7. 苹果酸/盐对暗棕壤磷有效性及林木吸收磷的影响%Effects of Malic Acid/Malate on Phosphorus Availability of Dark Brown Forest Soils and Absorption of Forest Seedlings

    Institute of Scientific and Technical Information of China (English)

    宋金凤; 宋俊杰; 褚永磊; 王勇; 崔晓阳; 彭红梅

    2011-01-01

    By simulating malic acid/malate contents in forest litter leachates,the effects and mechanism of different concentrations of malic acid/malate solutions on phosphorus(P) availability of air-dry dark brown forest soils were studied.By pot experiments,the role of malic acid/malate solutions on solublizing P were validated in natural dark brown forest soils,and the effects of malic acid/malate on P absorption of Larix olgensis and Fraxinus mandshurica seedlings were also discussed.The results showed that,malic acid and malate substantially encouraged soil P release of air-dry A1 and B horizons soils,and dissolved P contents increased with the extractant concentrations,but the effects on B horizon were relatively weak.Malate solutions had much higher soil-P-release efficiency than that of malic acid at the same concentration,therefore,the mechanisms for malic acid and malate to solublize P should be dominated by reactions of malate anion.The effects of malate anion on P release was found to be cumulative,and the amount of P released was primarily controlled by cumulative malate loading rate.When malate anion was loaded as sodium malate solutions,the regression equation between A1 horizon P release and cumulative malic loading rate was:Y=-0.0005X2+0.1929X+1.8192,R2=0.959 3.Merely on a quantitative basis of malate anion leached from forest litter,the increased P release from A1 horizon was estimated to be 3.04 kg/(hm2·a),accounting for 1/4~1/3 of the annual P absorption in middle-aged forests.The results of natural dark brown forest soils' experiments also showed that,malic acid/malate solutions of appropriate concentrations could stimulate soil P release,and were also helpful for P absorption of Fraxinus mandshurica and Larix olgensis seedings.In the processes of P mobilization and absorption,the concentration of 1.0 mmol/L or 5.0 mmol/L had the best function,and malate was better than malic acid.%模拟森林凋落物淋洗液中苹果酸/盐浓度范