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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The ratios of the plastic shear strain and tensile strain to the resolved shear strain are determined on the basis of earlier results obtained by computer for 1 0 0 and 1 1 1 textures and nontextured polycrystals in the case of simultaneous shear and extension. It is shown that the plastic deformation increment vector determined by the application of the plastic work equation fulfils the normality condition prescribed by the generalized flow law. 相似文献
992.
993.
994.
Summary A kinematic hardening model is generalized by introducing plastic and viscous residual back stresses , that govern the translation of the yield surface. The evolution equations for and are proposed and the material functions are identified for a construction steel by carrying out tension-compression tests at different strain rates. The cyclic tests with changing strain amplitudes and frequencies are next carried out and model predictions are compared with experimental results.
With 14 Figures 相似文献
Ein viskoplastisches Stoffmodell und seine Anwendungen bei zyklischer Belastung
Zusammenfassung Ein Modell mit kinetmatischer Verfestigung wird durch die Einführung plastischer und viskoser bleibender Hintergrundspannungen , verallgemeinert, die die Bewegungen der Fließfläche steuern. Die Wachstumsgleichungen für und werden aufgestellt und die Materialfunktionen für einen Baustahl aus Zug-Druckversuchen mit verschiedener Dehnungsrate bestimmt. Die zyklischen Versuche mit sich ändernden Dehnungsamplituden und Fequenzen werden als nächstes durchgeführt und die Modellaussagen mit den experimentellen Ergebnissen verglichen.
With 14 Figures 相似文献
995.
Annelise E. Gerbase José R. Gregório Márcia Martinelli Márcia C. Brasil Ana N. F. Mendes 《Journal of the American Oil Chemists' Society》2002,79(2):179-181
We studied the methyltrioxorhenium (MTO)-CH2Cl2/H2O2 biphasic system for epoxidizing soybean oil. The reactions were optimized (reactant ratio, time, and temperature), which
resulted in a better performance (higher conversion and selectivity) than those described in the literature. Total doublebond
conversion and 95% selectivity were obtained in 2 h at room temperature. Furthermore, it was possible to reach desired epoxidation
degrees by changing the oxidant and MTO amounts. The rhenium-epoxidized soybean oil remained stable in the absence of stabilizers
for up to 30 d when stored at mild conditions. 相似文献
996.
The basis of the examination is a clinical material of 14 years (from 1960 to 1973) of the urological clinic of the Medical University "Semmelweis", consisting of 160 patients with renal hypoplasia. In 116 of these cases a nephrectomy was performed. The average postoperative observation time was 7.8 years. By removal of the hypoplastic kidney the hypertension could be successfully influenced in 72% of the cases and in 16% moderately; in 12% of the patients the high blood pressure remained unchanged also after the intervention. On account of the recognition resulting from the examinations that by the hypoplastic kidney alone no increase of the blood pressure is caused, but the developmental anomaly forms a basis for the development of the hypertension, is emphasized that the early removal of this abnormally developed kidney is by all means indicated. 相似文献
997.
Between 1945 and 1970, 101 children (86 girls and 15 boys) with systemic lupus erythematosus were evaluated at the Mayo Clinic. Only 9 children were less than 9 years old at the time of diagnosis. The most frequent presenting complaint was arthralgia; fever, fatigue, and a "butterfly" malar rash also were common. Renal involvement, found in more than 76 per cent of patients, was a prognostically poor sign. The overall survival of children with renal involvement is improved by the use of adequate steroid therapy. 相似文献
998.
Beta brass single crystal, bicrystal and tricrystal stress strain behavior were determined for a series of isoaxial specimens
in which the bicrystals and tricrystals were incompatible in shear along the grain boundary. Volume fractions of grain boundary
deformation were also determined to ascertain the effect of increased constraint on grain boundary strengthening. It was found
that bicrystal flow stress was considerably higher than single crystal flow stress and that tricrystal strain hardening was
only slightly larger than that of the bicrystal. For the tricrystals the grain boundary deformation zone is larger than that
of corresponding bicrystals because of both configurational and constraint effects. This larger zone indicates that secondary
stresses extend further from the boundary in tricrystals than in bicrystals. It was concluded that despite increased constraint,
, the average grain boundary stress for the tricrystals, is smaller than that for corresponding bicrystals and that because
of the increased extent of the secondary stress,σ
b
i, the stress in the center component away from the grain boundary, is higher than that of the single crystal at corresponding
strains. The relationship of these observations to corresponding stresses in polycrystalline material is examined.
where Taek Dong Lee was formerly a Graduate Student.
This paper is based on a thesis to be submitted by Taek Dong Lee in partial fulfillment of the requirements for the degree
of Doctor of Philosophy at Polytechnic Institute of New York. 相似文献
999.
1000.
The study analyzes variables that influence the water management model based on a simultaneous relationship between competing demands in the Marina Baja of Alicante, using a methodology that directly links together urban and irrigation demands, making them relevant to each other from a socioeconomic point of view. The paper identifies the relevant variables of this model and the agent behaviour in a closed and joint system. It also aims to demonstrate that by considering water demands for different yet simultaneous uses and regarding clean and reclaimed waters as integrated resources, the system could remain in equilibrium without external water supplies. 相似文献