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991.
O. B. Gol’tsova V. S. Klekovkin O. B. Nagovitsin S. V. Antonychev 《Glass and Ceramics》2006,63(3-4):127-129
The results of experimental studies of heat losses via the enclosing structures of an operating brick-firing kiln using a
thermal imager are described.
__________
Translated from Steklo i Keramika, No. 4, pp. 24–25, April, 2006. 相似文献
992.
O. V. Elyukhina G. S. Sokolovskiĭ V. I. Kuchinskiĭ V. A. Elyukhin 《Technical Physics Letters》2006,32(9):818-820
Conditions providing a thermodynamic advantage governing the self-assembly of Zn and Te impurities in metastable magnesium sulfide (MgS) with zinc-blende structure have been theoretically studied. The formation of tetrahedral 1Te4Zn cells is thermodynamically favorable in ZnxMg1 ? x TeyS1 ? y (x ≥ 4y) solid solutions enriched in MgS in the region of dilute Te concentrations. At temperatures selected for the growth (230°C) and annealing (500°C), the free energy of a solid solution in which separate Te atoms must be surrounded only by Zn atoms is lower than that of the solution with a random arrangement of these impurities. This phenomenon is due to a thermodynamic advantage of the formation of Mg-S and Zn-Te bonds over Zn-S and Mg-Te bonding, as well as due to a decrease in the elastic strain energy upon self-assembly of the given isoelectronic impurities. 相似文献
993.
A. Cravino P. Leriche O. Alvêque S. Roquet J. Roncali 《Advanced materials (Deerfield Beach, Fla.)》2006,18(22)
The cover image illustrates the dual photovoltaic and electroluminescence function of a single‐layer device based on a thienylenevinylene–triphenylamine with internal charge transfer (ICT), as reported by Cravino, Roncali, and co‐workers on p. 3033. The material forms an organic glass with isotropic electronic properties while ICT leads simultaneously to an extension of the photoresponse to the red and to an increase of the open circuit voltage. The use of an additional layer of C60 further improves the photovoltaic. Images of the sun and moon courtesy NASA/JPL–Caltech. 相似文献
994.
A. Samuelsson O. C. Zienkiewicz 《International journal for numerical methods in engineering》2006,67(2):149-157
This paper presents a brief history of the development of the stiffness method. We start by tracing the evolution of the method to solve discrete‐type problems such as trusses and frames composed of two node members. We then describe the method as it is applied to solve continuum problems modelled by finite‐difference and finite‐element methods. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
995.
Mössbauer emission spectroscopy at 73As(73Ge) is used to show that the charge state of the 73Ge antisite defect formed in the anion sublattice after the radioactive transformation of 73As is independent of the position of the Fermi level. In contrast, the 73Ge center in the cation sublattice of PbSe is an electrically active substitutional impurity. For the n-type samples, the spectrum corresponds to the neutral state of the donor center (73Ge2+), and for the p-type samples, the spectrum corresponds to the doubly ionized state (73Ge4+) of this center. 相似文献
996.
Epoxidation of hexene-1 and cyclohexene in the systems H2WO4/H2O2-H2O/H3PO4 was studied under the phase-transfer catalysis conditions depending on the ratio between the reactants Na2WO4 and H3PO4 (in the presence of excess H2O2) and pH of the water phase. The interrelation between the pH of the aqueous phase, the composition of phosphatooxoperoxotungstate ions formed, and the catalytic activity of the systems was established. The complexes Q3[PO4{WO(O2)2}4] and Q2[HPO4{WO(O2)2}2], where Q+ is the lipophilic cation of a phase-transfer agent whose nature can have a noticeable effect on the composition of peroxoheteropoly compounds formed, exhibited the highest activity. To achieve the maximum catalytic activity, it is necessary to maintain the stoichiometric reactant ratio corresponding to the composition of peroxo complexes that prevail in a given pH range. 相似文献
997.
It is generally appreciated that the mechanical behavior of granular media depends fundamentally on the interaction of the
constituent particles, and that the validity of numerical models of granular media would be greatly improved with knowledge
of the grain-scale mechanics. However, most supporting experimental work has been conducted on highly idealized materials,
and a limited amount of information exists on grain-scale force–displacement relationships for naturally occurring materials.
To address this shortcoming, we are conducting a program that integrates laboratory experiments on grains of naturally occurring
aggregate with the discrete element modeling method, with the goal of relating the grain-scale physical and mechanical properties
of granular media to bulk behavior. The paper describes the equipment and methods that have been developed to conduct close-loop
controlled, grain-scale experiments under monotonic and cyclic loading conditions, and presents results from an initial set
of experiments on unbonded grains. The implications of the grain-scale results to the discrete element model are discussed.
Discussions center on the applicability of a physically based approach to the mechanics of granular media in general. In light
of future exploration missions and the resulting need to predict the mechanical properties of lunar and planetary regoliths,
the paper examines the potential usefulness of our physically based approach to the problem of predicting the behavior of
the types of materials found in those environments. 相似文献
998.
999.
The study focused on the in-situ synthesis of titanium (Ti)-titanium boride (TiB) composites with β phase in the matrix by reaction sintering of TiB2 with Ti and alloying element powders. The goal was to examine the nature of TiB whisker formation in three different kinds
of powder mixtures: (1) β-Ti alloy powders and TiB2; (2) α-Ti powder, a master alloy (Fe-Mo) powder containing the β-stabilizing elements, and TiB2; and (3) α-Ti powder, a β-stabilizing elemental powder (Mo or Nb), and TiB2. The effects of powder packing and the relative locations of powder particles on the morphological changes in TiB whisker
formation and their growth were studied at processing temperatures ranging from 1100°C to 1300°C. The morphology, size, and
distribution of whiskers were found to be influenced by the powder-packing conditions. A large particle-size ratio in bimodally
packed mixtures led to the formation of a TiB monolithic layer around β grains. With a relatively finer starting powder, smaller size ratio, and trimodal packing arrangement, the TiB whiskers were
found to be distributed more homogeneously in the matrix. The study also used the X-ray direct comparison method and the structure
factor for the β phase to determine the volume fraction of TiB phase from X-ray data. Tensile tests and fractographic investigations were
carried out on selected composites. The evolution of the composite microstructure, the influence of powder-packing variables,
and the morphology and growth of TiB whiskers and their effect on mechanical properties are discussed. 相似文献
1000.
G. E. Cirlin V. G. Dubrovskii A. A. Tonkikh N. V. Sibirev V. M. Ustinov P. Werner 《Semiconductors》2005,39(5):547-551
Atomic-force microscopy is used to study the behavior of an array of Ge islands formed by molecular-beam epitaxy on an Si (100) surface in the presence of an antimony flux incident on the surface. It is shown that, as the Sb flux increases to a certain critical level, the surface density of the islands increases; however, if this critical level is exceeded, nucleation of the islands is suppressed and mesoscopic small-height clusters are observed on the surface. This effect is explained qualitatively in the context of a kinetic model of the islands’ formation in heteroepitaxial systems mismatched with respect to their lattice parameters. 相似文献