基于曲线拟合的轮胎帘布层转向残余回正力矩计算方法分析

介绍和分析线性拟合法、关键区线性拟合法和三次曲线拟合法3种轮胎帘布层转向残余回正力矩(PRAT)测试数据的处理方法。结果表明:采用不同的曲线拟合方法得到的PRAT值有较大的区别;三次曲线拟合法操作方便,计算得到的PRAT值更精确。     

基于曲线拟合的轮胎PRAT计算方法分析

轮胎PRAT(Plysteer Residual Aligning Torque)的值一般较小,计算PRAT所需轮胎力学特性的测试精度要求较高,对测试数据的不同处理方法也会得到不同的PRAT值。本文介绍了三种测试数据的曲线拟合方法,通过分析得出三次多项式曲线拟合法可以更方便地得到较精确的PRAT值。     

Study on Reduction of MoO2 Powders with CO to Produce Mo2C

Molybdenum hemicarbide (Mo₂C), which is widely applied in steel and metal ceramics as well as catalysts, was successfully synthesized by using a simple method of reducing MoO₂ powders by CO. It was found that the final reduction product was all Mo₂C under both isothermal and nonisothermal conditions. However, the reduction mechanisms were significantly different at lower and higher temperatures: at lower temperatures (1070 to 1342 K), reduction of MoO₂ to Mo₂C followed a one‐step reaction (simultaneous reduction and carburization), while at higher temperatures (1423 to 1485 K), MoO₂ was first reduced to metallic Mo, and then Mo was carburized to Mo₂C. Mo₂C particles obtained at higher temperatures contained micrometer‐sized surface features which formed during the MoO₂ to Mo reduction step.     

一类n维Lotka—Volterra模型的稳定性特征

本文给出n维Lotka-Volterra合作系统局部渐近稳定性和全局稳定性的判别条件,并证明该系统正平衡位置的稳定性特征:局部渐近稳定性和全局稳定性是等价的.     

热处理工艺对GH33A合金高温低周疲劳寿命的影响

本文研究了不同热处理工艺对GH33A高温合金在550℃时的低周疲劳寿命和循环变形行为的影响。结果表明,当应变范围△ε_l<1.2％时,采用双级时效工艺(B工艺)可获得最长的疲劳寿命;当应变范围△ε_l>1.2％时,采用标准热处理工艺可获得较长的疲劳寿命。热处埋工艺不同,合金的循环变形行为也不同。应根据具体构件的受力条件来制定合理的热处理工艺。以发挥合金的潜力.     

大口径抛物反射面天线的准光理论分析

文中用准光理论分析了大口径抛物反射面天线的波束变换特性，讨论了天线性能与辐射波束尺寸、馈源波束尺寸的关系，探讨了用准光理论设计天线的可能性，给出了若干有实用价值的计算公式。     

无机盐生产中的锶钡分离

锶钡分离对于生产高纯锶、钡盐及利用高锶 钡矿或高钡锶矿具有重要意义。介绍、评论了沉淀、离子交换、溶剂萃取等方法的研究和在无机盐工业中应用的情况。     

甲基丙烯酸酯类光刻胶成膜树脂的合成与性能研究

以甲基丙烯酸(MAA)、甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)为单体,偶氮二异丁腈为引发剂,采用溶液自由基聚合方法,合成了甲基丙烯酸酯类光刻胶成膜树脂,研究了合成工艺对产物分子量及分子量分布的影响,并对其在光刻胶中的应用性能,如碱溶性、涂膜表面干燥性、感度和分辨率等进行了初步考察。结果表明,在引发剂用量为单体用量的0.6%~1%、反应温度80~85℃、3次进料条件下,制得的聚合物的重均分子量为44 341~53 696,分子量分布为3.66~5.69,由单体质量比MAA∶MMA∶BA为25∶50∶25的成膜树脂配制的光刻胶,分辨率达35μm。     

多相搅拌槽内宏观混合研究进展

多相搅拌槽反应器广泛应用于化工、冶金等过程工业中,而多相混合状态对于多相搅拌槽反应器的设计、优化和放大具有重要意义.混合时间是表征其宏观混合过程的一个重要参数.文中从实验和数值模拟二方面对多相搅拌槽反应器的液相混合时间研究进行综述,对气液、液固、液液、气液固4种体系的多相搅拌槽进行了分类总结,讨论了分散相、桨型、转速、...     

Carbon nanosheets with catalyst-induced wrinkles formed by plasma-enhanced chemical-vapor deposition

Substrates with and without catalyst layers have been tested for the capacitively coupled radio-frequency plasma-enhanced chemical-vapor deposition of carbon nanosheets (CNSs) at a temperature as low as 500 °C. Glass coated with Ni, Ni/Co, Co/Ni, and Ni/Zn and glass without a catalyst layer were used as the substrates. CNSs were only obtained on substrate samples with a catalyst layer. The morphology of the CNSs was catalyst dependent. Both flat and standing CNSs were obtained. Transmission electron microscopy analysis revealed that the CNSs deposited on a Ni/Zn catalyst layer have densely distributed catalyst-induced wrinkles, while still sustaining a planar structure. The numerous wrinkles mean that these CNSs may serve as catalyst supports, ultracapacitor electrodes and gas-sensor materials. Electron diffraction and Raman studies showed that the CNSs obtained in this experiment are reasonably graphitized.