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991.
992.
简要分析了升船机上闸首基础岩体的特点,在施工期随上部建筑物形成的过程中沉降与水平形变随荷载变化的特征。分析认为:基础岩体形变与其受荷特点相吻合,目前建筑物总体安全状态正常,但部分坝段需引起注意,同时为验证设计、指导施工提供了依据。 相似文献
993.
David Mills 《Granular Matter》2004,6(2-3):173-177
For fine powdered materials, capable of being conveyed in dense phase, a conveying region exists in which instability in flow and pipeline blockage can occur if the pressure gradient available is insufficient to maintain a minimum value of solids loading ratio. A reduction in material flow rate can also lead to pipeline blockage in this region. Conveying trials under-taken with cement are used to illustrate the nature of the problem. 相似文献
994.
995.
The boundary knot method (BKM) of very recent origin is an inherently meshless, integration‐free, boundary‐type, radial basis function collocation technique for the numerical discretization of general partial differential equation systems. Unlike the method of fundamental solutions, the use of non‐singular general solution in the BKM avoids the unnecessary requirement of constructing a controversial artificial boundary outside the physical domain. The purpose of this paper is to extend the BKM to solve 2D Helmholtz and convection–diffusion problems under rather complicated irregular geometry. The method is also first applied to 3D problems. Numerical experiments validate that the BKM can produce highly accurate solutions using a relatively small number of knots. For inhomogeneous cases, some inner knots are found necessary to guarantee accuracy and stability. The stability and convergence of the BKM are numerically illustrated and the completeness issue is also discussed. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
996.
A. Moropoulou N. Kouloumbi G. Haralampopoulos A. Konstanti P. Michailidis 《Progress in Organic Coatings》2003,48(2-4):259-270
Susceptibility of stone to salt decay is directly related to its microstructural and mechanical characteristics. In the present work, a porous stone from a quarry in Cyprus was examined. Samples of this stone were consolidated and protected with certain conservation materials. The modification of microstructural characteristics of the stone was evaluated by mercury intrusion porosimetry, while its mechanical characteristics were measured by compressive and bending strength tests. From these data, the susceptibility of Cyprus stone to salt (NaCl) decay was estimated. The values of crystallization pressure of NaCl were calculated and compared to the experimentally measured compressive and tensile strength of the stone, in order to examine the probability of stone disruption due to salt crystallization. The development of the phenomenon after coarse pores’ filling with crystals, i.e. crystallization of salts in capillaries or mechanical failure of the stone, was determined by thermodynamic analysis. Additionally, artificial weathering tests of marine salt spray were performed for the evaluation of stone’s durability after the conservation. The treated stone proved to be resistant to salt decay, as it presented ameliorated microstructural and mechanical characteristics, concerning decay due to soluble salt crystallization. The most possible thermodynamic scenario was small pores repletion with crystals, avoiding mechanical failure of the stone. 相似文献
997.
This article theoretically investigates the drying of uncoated paper with gas-fired infrared (IR) emitters installed within the drying section of a given commercial paper machine. Specifically, it presents the ideal location of two opposing IR emitters within the drying section. The ideal location of the two opposing IR emitters corresponds to the highest machine speed with specified average moisture content of paper sheet at the end of the drying section. This article also presents the average evaporation rate, temperature, and moisture content of the paper sheet as it travels through the drying section with the two opposing IR emitters operating at the optimum location. In addition, the temperature and moisture profiles in the sheet thickness direction, before and after the IR emitters, are provided. This article is not concerned with the potential effects of drying with IR emitters on paper sheet properties and machine runnability issues. 相似文献
998.
999.
1000.
Acid Green 25, which is a diazoic dye bearing two sulfonic groups, is efficiently sorbed on chitosan. The protonation of chitosan may explain the electrostatic attraction of this anionic dye and that its optimum pH is close to 3. Preliminary protonation of amine groups (obtained by contact with a sulfuric acid solution) reduced the variation of solution pH following sorbent addition but significantly reduced sorption performance: the maximum sorption capacity of raw chitosan, 525 mg dye/g (0.84 mmol dye/g), was halved by acidic preconditioning. The acidic conditioning also reduced the kinetic rate—the time necessary to reach equilibrium increased up to threefold depending on the experimental conditions. The size of sorbent particles influenced sorption kinetics and equilibrium because of resistance to intraparticle diffusion, but the sorption appeared to occur not only at the surface of the sorbent but also in the intraparticle network of the polymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1073–1080, 2003 相似文献