The Temperature Distribution of a Two‐Dimensional Thermoelastic Material with Voids

In this paper, an attempt has been made to investigate the temperature field in a two‐dimensional thermoelastic medium with voids. This takes place when it is subjected to a time‐dependent temperature source under the conditions of conduction heat transfer and interaction between the thermoelastic medium and its surroundings. Analytical expressions of displacements, stresses, temperature increment, and change in the volume fraction field for a layer of thermoelastic medium and a half‐space thermoelastic problem are derived by using the Laplace and Fourier transformation techniques. Two scalar potential functions of the displacement are introduced in the solution process. Then, the integral transform is inverted by using a numerical technique, and numerical results are illustrated graphically to analyze the distribution of the fields. Furthermore, the influence of the thermo‐void coefficient for two kinds of temperature boundaries is discussed. A comparison is also presented with the corresponding half‐space thermoelastic model without voids to ascertain the validity and the difference between these models. © 2010 Wiley Periodicals, Inc. Heat Trans Asian Res; 39(7): 507–522, 2010; Published online in Wiley Online Library ( wileyOnlinelibrary.com ). DOI 10.1002/htj.20313     

气流磨处理对钼粉物理性能的影响

研究了微型流化床对撞式气流磨处理对普通钼粉物理性能的影响。气流磨处理后,钼粉的松装密度、振实密度大幅提高;钼粉粒度分布变窄、d50明显减小;通过SEM分析发现,钼粉颗粒形貌均匀、团聚体全部被打开。另外经气流磨处理,适当调节分级器转速,可以在一定的范围内有效地调节钼粉的费氏粒度。总之,气流磨处理是改善钼粉物理性能的一种有效方法。     

脉冲电源辉光等离子渗Ti的工艺研究

在低碳钢表面利用脉冲电源进行辉光离子渗Ti工艺研究。结果表明:在本工艺条件下,能够获得200μm以上的渗层,其组织形貌为渗层与基体之间形成一条明显的反应扩散分界线,且分界线两边均出现较为明显的柱状晶;渗Ti层的结构主要由Fe2Ti、Fe-Ti、TiC相组成;随着电压的升高,渗Ti层增加,550V时达到最厚,表面Ti含量也最高,当电压超过550V后,渗层厚度减小、Ti含量降低;随时间的增长,渗Ti层厚度增加,表面Ti的含量增加;渗层厚度随温度的升高而变厚,渗层Ti的含量也随之变大。     

环氧树脂的加入对水性聚氨酯性能的影响

以聚丙二醇、异佛尔酮二异氰酸酯、2,2-二羟甲基丁酸、环氧树脂E51等为主要原料,通过丙酮法制备环氧树脂改性聚氨酯乳液.探究了环氧树脂E51的用量对聚氨酯贮存稳定性、力学性能、热稳定性的影响.结果表明,环氧树脂E51的最佳用量为6％(质量分数).通过傅里叶红外光谱分析证明了环氧树脂E51成功的连接到了聚氨酯的主链上.     

基于Isight反求界面传热系数的研究

以试验测得的温度为基础,基于Isight平台,结合数值模拟方法和模拟退火算法的优化方法,计算求解了A356铝合金铸件冷却凝固过程中铸件与金属铸型间的界面传热系数。采用优化软件Isight集成铸造仿真软件ProCAST,成功解决了这两个软件的接口问题,而且在后处理数据的提取方面,采用均匀步长的计算,与整理后均匀时间步长的试验数据能更好的匹配,从而方便计算优化目标。另外,它不仅可以准确计算出随温度或时间变化的传热系数,而且还可以应用该方法优化铸造工艺和模具。     

不同密度水泥石和微环尺寸情况下的套管波特征

利用声波变密度测井评价固井质量时,掌握不同情况下套管波的特征有助于套管波的分析和剔除,提高固井质量评价的精度。利用实轴积分法模拟分析了不同密度水泥石、不同微环尺寸情况下的套管波时域和频谱特征。结果表明:对于正常密度水泥石,第一、二界面完全胶结时,无套管波;第一界面存在不同尺寸微环时,套管波出现且套管波频率相同,但幅度差别不大。对于低密度水泥石,第一、二界面完全胶结时,出现较小幅度套管波,且水泥石密度越低,套管波幅度越大;第一界面存在不同尺寸微环时,套管波出现且各套管波频率相同,但幅度差别不大。对于同一套管,不同密度水泥石、不同微环尺寸情况下套管波具有相同的频率。      

MEMS硅梁谐振式传感器的研究

通过对硅梁谐振式传感器工作原理的研究,结合Intellisuite软件对硅微悬臂梁谐振器的振动特性进行了分析,设计了具有悬臂梁结构的电热激励/压阻拾振的谐振式传感器,这种传感器具有体积小、功耗低、灵敏度高、准数字信号输出、成本低、与集成电路工艺兼容等优点。对研究制作过程中的关键工艺——各向异性腐蚀技术,尤其是对低温下的腐蚀工艺进行了实验研究,采用高低温相结合的湿法腐蚀工艺制作了微悬臂梁结构,通过实验分析了利用新型有机薄膜对各向异性腐蚀过程中的MEMS器件金属电极的保护效果,为实际生产和设计提供了参考依据。     

三黄鸡肉挥发性香气成分的研究

以三黄鸡鸡腿肉为研究对象,采用同时蒸馏提取法(Simultaneous Distillation Extractor, SDE)提取挥发性香气成分,并用气-质联用法(GC-MS)对香气成分进行鉴定.试验结果表明,三黄鸡鸡腿肉香气成分中包含23种化合物,主要有:烷烃、烯烃、醛类、酮类、酯类、醇类、芳香族、酸类,其中羰基化合物最多,烷烃次之.为确定其主体香气成分、改善和评价鸡肉产品品质奠定了基础.     

Content of trichodiene and analysis of fungal volatiles (electronic nose) in wheat and triticale grain naturally infected and inoculated with Fusarium culmorum

Four groups of cereal kernels were analyzed in terms of their volatile metabolite contents using GC/MS and the electronic nose. Analyses were conducted on 36 triticale breeding lines and 22 wheat breeding lines. Grain came from field samples inoculated with Fusarium culmorum and simultaneous non-inoculated samples-controls. All sample groups contained significantly varied levels of trichodiene (TRICH), a precursor for the formation of fusarium metabolites, with approx. two times higher concentration recorded in triticale. In inoculated samples TRICH concentration for wheat was on average six times higher and for triticale eight times higher than in non-inoculated samples. In the course of analysis using the electronic nose in tested groups of grain differences were observed in the profiles of detected volatile compounds. This resulted in a statistically significant distribution of investigated samples into four objects.     

Theoretical and experimental study of dry scroll vacuum pump

The rarefied gas flows through suction port, scroll clearance and discharge port are treated as leakage of dry scroll vacuum pump (DSVP). The models for predicting the above-mentioned leakage rate were derived in this paper. The model for predicting the heat transfer rate between rarefied gas and working chamber wall was also developed. Then, a general model for describing the working process of DSVP was set up according to the energy and mass conservation principle. This model can be applied to predict the performance of DSVP. The pumping speed for different suction pressures was obtained. Furthermore, the ultimate pressure and power consumption for different speeds were gotten. A good agreement between the theoretical results and experimental data was obtained. Finally, the volume ratio of prototype was changed and its influence on the performance was studied by experiment.