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131.
A. Moran C. Madden R. Rebis R. Payne M. A. Matteson 《Journal of Thermal Spray Technology》1994,3(2):197-198
Over the past five years, the Annapolis Detachment, Carderock Division, Naval Surface Warfare Center (formerly David Taylor
Research Center) has established a state- of- the- art spray forming facility for the study and exploitation of this near
net shape manufacturing process. Spray forming is a single step gas atomization/deposition process which yields ferrous and
nonferrous, near final shape, near fully dense preforms that has proven to be a viable and cost effective alternative to conventional
metalworking technology for the production of material preforms with properties surpassing those of their cast and wrought
counterparts. Current programs at Carderock Divison Naval Surface Warfare Center are aimed at optimization of the process,
certification of the spray formed products and industrialization of the technology. 相似文献
132.
一步法合成松香改性酚醛树脂 总被引:2,自引:0,他引:2
探讨了一步法合成松香改性酚醛树脂的反应机理,确定了最佳原料组成及合成工艺,由此制备出高溶解粘度和矿油容纳度的松香改性酚醛树脂,是一种性能优异的高级胶印油墨连接料 相似文献
133.
A new method for characterization of stratified thermal energy stores (TES) that integrates both the first law and the second law concerns is presented here. The first law concern is incorporated into a quantity called energy response factor and the second law concern into an entropy generation ratio. A product of these two quantities is at the heart of the TES efficiency definitions. This approach removes the overemphasis of the existing methods either on the first or the second law of thermodynamics which often biases the characterization results. The information about the evolution of the temperature field of the system in time is the prerequisite of the new method. It may be obtained from experiments or from suitable numerical simulations. The current method can be easily integrated into computational fluid dynamic (CFD) simulations and thus facilitate CFD-based design analysis. As an example of such CFD-integrated analysis, a large-scale hot water seasonal heat store is numerically studied to identify the effects of aspect ratio, containment shape, internal structures, and containment size on their efficiency. The results suggest the effectiveness of the new method in deriving useful design insights. 相似文献
134.
135.
136.
研究了18种具有不同孔结构参数的粒状铜基甲醇合成催化剂孔隙率对有效扩散系数的影响。结果发现,催化剂微孔孔隙率增大,曲节因子亦增大,扩散阻力增加。将孔隙率与催化剂曲节因子关联,得到了半经验方程,用它可估算催化剂的曲节因子。 相似文献
137.
To confirm the reliability of the theory of phase equibria of multicomponent polymer 1/multicomponent polymer 2 systems (i.e. quasi-binary systems) and the method of computer experiment based on this theory (Brit. Polym. J., 23 (1990)285; 23 (1990)299; Polym. Int., 29 (1992)219), could point curves (CPC), two-phase volume ratios ( R ) and critical solution points (CSP) have been determined experimentally for the quasi-binary mixtures of poly(ethylene oxide) (M¯w = 647, M¯w/M¯n = 1.15; M¯w and M¯n, the weight-average and numberaverage molecular weights, respectively) and poly(propylene oxide) (M¯w = 2028, M¯w/M¯n = 1.08; and Mw = 2987, Mw/Mn = 1.13). The hydroxyl end groups of both polymers were methoxylated in advance by the Cooper & Booth method (Polymer, 18 (1977)164). The thermodynamic interaction parameter between both polymers, χ12, and the concentration dependence parameters for the above quasi-binary systems were determined by the method proposed in a previous paper (Brit. Polym. J., 23 (1990)299). CPC, R and CSP values calculated on the basis of the theory are in good agreement with the values determined experimentally. 相似文献
138.
The present investigation showed that the re-laxation peak at about 200℃ (f≈1Hz) was relatedto bainitic transformation in a CuZnAl alloy.Thepeak decreased when bainite precipitated.Theactivation energy of the peak was the same as theapparent activation energy of bainitic transforma-tion.According to the relations between the peakand the bainitic transformation,the mechanism ofthe peak has been discussed. 相似文献
139.
孔型热轧时轧制力的实用计算公式 总被引:2,自引:0,他引:2
采用修正系数法,利用板材在带刻槽的冲头进行深冲与平面冲头下深冲时的接触压力的比值确定孔型影响系数,进而推导出孔型热轧时轧制力的实用计算公式. 相似文献
140.
Detection of multiple cracks using frequency measurements 总被引:2,自引:0,他引:2
D.P. Patil 《Engineering Fracture Mechanics》2003,70(12):1553-1572
A method for detection of multiple open cracks in a slender Euler-Bernoulli beams is presented based on frequency measurements. The method is based on the approach given by Hu and Liang [J. Franklin Inst. 330 (5) (1993) 841], transverse vibration modelling through transfer matrix method and representation of a crack by rotational spring. The beam is virtually divided into a number of segments, which can be decided by the analyst, and each of them is considered to be associated with a damage parameter. The procedure gives a linear relationship explicitly between the changes in natural frequencies of the beam and the damage parameters. These parameters are determined from the knowledge of changes in the natural frequencies. After obtaining them, each is treated in turn to exactly pinpoint the crack location in the segment and determine its size. The forward, or natural frequency determination, problems are examined in the passing. The method is approximate, but it can handle segmented beams, any boundary conditions, intermediate spring or rigid supports, etc. It eliminates the need for any symbolic computation which is envisaged by Hu and Liang [J. Franklin Inst. 330 (5) (1993) 841] to obtain mode shapes of the corresponding uncracked beams. The proposed method gives a clear insight into the whole analysis. Case studies (numerical) are presented to demonstrate the method effectiveness for two simultaneous cracks of size 10% and more of section depth. The differences between the actual and predicted crack locations and sizes are less than 10% and 15% respectively. The numbers of segments into which the beam is virtually divided limits the maximum number of cracks that can be handled. The difference in the forward problem is less than 5%. 相似文献