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141.
ANALYTICAL EVALUATION OF PERMANENT DEFLECTION OF A THIN CIRCULAR PLATE STRUCK NORMALLY AT ITS CENTER BY A PROJECTILE 总被引:1,自引:0,他引:1
Chen Liebin Yang Jialing 《Acta Mechanica Solida Sinica》2007,20(2):117-122
The permanent deflection of a thin circular plate struck normally at its center by a projectile is studied by an approximate theoretical analysis,FEM simulation and experiment.The plate made of rate sensitive and strain-hardening material undergoes serious local deformation but is not perforated during the impact.The theoretical analysis is based on an energy approach, in which the Cowper-Symonds equation is used for the consideration of strain rate sensitive effects and the parameters involved are determined with the aid of experimental data.The maximum permanent deflections predicted by the theoretical model are compared with those of FEM sim- ulation and published papers obtained both by theory and experiment,and good agreement is achieved for a wide range of thickness of the plates and initial impact velocities. 相似文献
142.
143.
Cloudpoint data for polystyrene/methylcyclohexane solutions extending over moderate ranges of pressure and molecular weight are available in the literature. Those data are supplemented with new results from this laboratory to fill in gaps and extend the MW range (to 761 ≤ MW/amu ≤ 2 × 107). The resulting data net is discussed and reasons to extend studies to higher pressure are presented. © 1996 John Wiley & Sons, Inc. 相似文献
144.
提出了一种基于像差特征分析的变焦系统共轴性装调方法。针对某型20倍变焦光学系统的装调,在分析变焦光学系统装调要求的基础上,通过采用光学定心加工技术,提高变焦系统各镜组内光学元件的同轴度;采用Zygo干涉仪,检测变焦系统在长短焦位置的像差特性分布;借助CodeV软件仿真计算各光学元件在系统中的公差灵敏度分布,并确定产生像差影响的敏感光学元件;在中心偏测量仪上,完成最终光学系统像质的调整。此外,还设计了一种变焦光学系统各动组间同轴度调试装置,对变焦相机主镜筒机械内孔轴线与直线导轨的平行性进行了精确测量,保证了动组组元光轴的同轴精度。装调结果表明:变焦系统成像质量有明显改善,像面一致性得到保证,长短焦轴上传递函数值分别优于技术要求值0.45和0.55,长短焦轴外0.7视场传递函数值优于0.25和0.35,实现了高精度装调,验证了该方法的可靠性。 相似文献
145.
Czesław Rudowicz Ireneusz Stefaniuk Roman Dziembaj Hitoshi Ohta Marcin Molenda Susumu Okubo Makoto Yoshida 《Research on Chemical Intermediates》2007,33(8):853-862
This paper deals with the analysis of the temperature dependence of high-frequency EMR (HF-EMR) spectra due to Mn3+ and Mn4+ ions in the lithium manganese spinel LiMn2O4. A range of powder samples obtained by the sol-gel method with calcinations in several temperature ranges were prepared for
this study. Based on the initial characterization carried out by a number of techniques, the physicochemical and structural
properties of the samples were earlier determined. Independently, temperature magnetization and HF-EMR measurements were carried
out. The EMR spectra vary strongly between samples, indicating possible structural or chemical changes. Quantitative analysis
of the temperature dependence of the HF-EMR spectra due to Mn3+ and Mn4+ ions in LiMn2O4 is presented in this paper. The spectral analysis concerns the line shape, linewidth, intensity and g-factors. Fittings using the Lorentzian spectral shape and, to a certain extent, the Gaussian spectral shape have been carried
out in order to parameterize the temperature dependence of the HF-EMR spectra. This parameterization of the HF-EMR experimental
data enables a deeper characterization of the samples. Subsequently, a better insight into the role of the Mn3+ and Mn4+ ions in accounting for the characteristics most suitable for application of LiMn2O4 as a cathode material may be gained. 相似文献
146.
147.
DrugFET的研究(Ⅳ).硅钨酸—麻黄碱FET的研制与应用 总被引:5,自引:0,他引:5
将离子敏感场效应晶体管与药物敏感膜相结合研制成一种对盐酸麻黄碱有良好响应的药物敏感场效应晶体管传感器。 相似文献
148.
Enthalpies of protonation in aqueous solution have been determined from calorimetric measurements between 0 and 100°C for methylpentylamine, butyldimethylamine, and quinuclidine; between 0 and 125°C for di-iso-propylamine; and between 0 and 75°C for 1-azacycloheptane. Values ofpKa at 25°C have been determined from pH measurements using a glass electrode for di-iso-propyl-, methylpentyl-, and butyldimethylamine. The calorimetric results are used together with values ofpKa at 25°C to derive expressions which allow the calculation of accuratepKa values over a large temperature range. The heat capacity and entropy changes for the protonation of aqueous alkylamines found in the present and in previous studies are discussed in terms of differences in hydrophobic solvation of the alkyl groups in the neutral amines and the ions. 相似文献
149.
The development of a user-friendly reusable laboratory equipment for the delivery of sensitive reagents and catalysts is described. The tightness of these Teflon Magnetic Stirring Capsules (TMSC) is ensured by the magnetic force and release of the reagent inside the solution is triggered by adjusting the stirring rate so that the centrifuge force exceeds the magnetic force. They can be loaded with several chemicals at the same time and do operate across a broad range of temperatures. The inertness of Teflon facilitates reaction purification. 相似文献
150.