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排序方式: 共有476条查询结果,搜索用时 15 毫秒
1.
2.
I. D. Kashcheev S. N. Sychev M. N. Dunaeva L. A. Karpets P. A. Emel’yanov O. S. Ryakhova 《Refractories and Industrial Ceramics》2008,49(2):131-134
Compositions have been developed for nonshrinking vibrocast thermally insulating light refractory concretes with densities
of 1.0, 1.3, 1.5, and 1.8 g/cm3 for temperatures of use up to 1400°C. The structure and properties have been examined for the concrete of density 1.3 g/cm3.
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Translated from Novye Ogneupory, No. 4, pp. 29–32, April, 2008. 相似文献
3.
The influence of the chemical reactions occurring in the gas phase of a gas suspension flowing in a channel with penetrable
walls and the combustion of the condensed-impurity particles in this flow on its gasdynamic structure has been investigated.
It is shown that the order of the system of equations defining a flow of a chemically reactive gas suspension with a homogeneous
exothermic reaction proceeding at a definite rate and a heterogeneous combustion of the condensed-phase particles can be decreased
if certain assumptions are mode. The distributions of the parameters of the gas and dispersed phases were calculated as functions
of the rate of blow and the sizes of the particles.
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Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 4, pp. 91–98, July–August, 2007. 相似文献
4.
Results are provided for an experimental study of forming trajectories during drilling and the effect on them of cutting speed
and drilling depth.
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Translated from Izmeritel’naya Tekhnika, No. 8, pp. 31–33, August, 2006. 相似文献
5.
6.
The quality of coke has a strong effect on the performance indices of a blast furnace. For a furnace to operate with high productivity and a low coke rate, it is necessary to use coke with high strength characteristics. The Novolipetsk Metallurgical Combine has conducted studies of the effect of coke quality on the operation of blast furnaces of different sizes. The quality of the coke was evaluated on the basis of the following indices: CSR, CRL, the cold-strength indices M10 and M25, and the integral coke-quality index Ig.c used by the Sidmar company. Furnace productivity, coke rate, and the totterman index (DMI) were also used for the sake of comparison. 相似文献
7.
A controlled release profile of salicylic acid (SA) for transdermal administration has been developed. Poly (vinyl alcohol) (PVA) and Poly(vinyl alcohol)/Poly(vinyl pyrrolidone) (PVP) blended preparations were used to prepare the membranes by solvent‐casting technique. The release of the drug from the membranes was evaluated at in vitro conditions. The effects of PVA/PVP (v/v) ratio, pH, SA concentration and temperature were investigated. 60/40 (v/v) PVA/PVP ratio was found to be the best ratio for the SA release. Increase in pH and temperature was observed to increase the transport of SA. Instead of blending PVA with PVP, N‐Vinyl‐2‐pyrrolidone (VP) was grafted onto the PVA and the delivery performance for SA was compared with that of the blended PVA/PVP membranes. Grafted membranes gave higher transport percentages than the blended membranes. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1244–1253, 2006 相似文献
8.
The use of isopropanol (IPA) as the reaction solvent for the preparation of high molecular weight segmented polyether-urea copolymers based on cycloaliphatic diisocyanates was investigated. Reactivity of IPA with bis(4-isocyanatohexyl)methane (HMDI) and isophorone diisocyanate (IPDI) was studied between 0 and 40 °C using in-situ FTIR spectroscopy. HMDI, which has secondary isocyanate groups, shows a very slow reaction with a large excess of IPA at 0 and 23 °C. Analysis of the kinetic data indicates an activation energy of 51 kJ/mol for the reaction between HMDI and IPA. As expected, IPDI, which has both a primary and a secondary isocyanate (NCO) group, reacts faster with IPA compared with HMDI, which only has secondary NCO groups. However, the rate of reaction of IPDI with IPA at 0 °C is extremely slow (approximately 1% consumption of isocyanate in 60 min) thus allowing the use of IPA as the reaction solvent for polyether-urea synthesis. Preparation of high molecular weight, high-strength HMDI and IPDI based polyether-urea segmented copolymers in IPA has been demonstrated. Thermal analysis and stress-strain analyses were used to characterize the products. 相似文献
9.
Thermoplastic polyolefin (TPO) films with permanent, silicone‐rich, low‐friction, low‐abrasion surfaces were obtained by melt blending of high‐density polyethylene (HDPE) and polypropylene (PP) with polydimethylsiloxane (PDMS)‐containing block copolymers. Two different block copolymers, a siloxane–urea segmented copolymer and a polycaprolactone‐b‐PDMS triblock copolymer were used as modifiers at levels between 0.1 and 5.0% by weight. Blends were prepared in a twin‐screw extruder. Modified films displayed surfaces with very low friction coefficients and high abrasion resistance, which depended on the type and the level of additive incorporated into the system. Bulk properties of these modified systems, such as crystallization and melting behavior or tensile properties, were not affected. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 535–540, 2002; DOI 10.1002/app.10279 相似文献
10.
R. Sadeler A. Ozel I. Kaymaz Y. Totik 《Journal of Materials Engineering and Performance》2005,14(3):351-355
The effect of tensile prestraining-induced residual stress on the fatigue life of notched steel parts was investigated. The
study was performed on AISI 4140 steel. Rotating bending fatigue tests were carried out on semicircular notched specimens
with different notch radii in the as-quenched and tempered conditions. Metallography of the specimens was performed by means
of light optical microscopy. The finite-element method was used to evaluate the residual stress distribution near the notch
region. Fatigue tests revealed fatigue life improvement for notched specimens, which changes depending on the notch radii
and applied stress. Scanning electron microscopy was used to examine the fracture surfaces of the specimens. 相似文献