力学探针在材料选区力学性能测量上的应用

介绍了力学探针的工作原理，并通过对不同应力状态下弹簧钢力学性能和TiN硬质薄膜力学性能的测量实例，展示了力学探针技术在材料选区力学性能评价上所具有的明显优势和广阔的应用前景。     

IC缺陷轮廓多分形特征研究

IC真实缺陷轮廓曲线的形状特征对集成电路成品率预报及故障分析有重要影响。该文提出缺陷轮廓曲线具有多分形特征,以某一真实缺陷为例,用小波变换模极大(WTMM)的方法估计了其轮廓曲线参数方程的多分形谱,该结果为硅片表面缺陷的精细表征及其计算机模拟作了有益探索。     

添加纳米SiO2粉体对Ti84Mo16合金性能优化的探索

针对"骨置换"材料的高强度、低弹性模量需求,基于粉末冶金制备工艺,对钛钼Ti84Mo16二元粉采用2 h球磨,然后在球磨粉中添加比例分别为1%、2%、5%纳米级SiO2粉后压坯成型,并在1 200℃条件下保温5 h固相烧结制备合金。研究发现,在Ti84Mo16合金中添加不同比例的SiO2后,其屈服强度提高17.92%,断裂强度提高5.8%,但合金塑性降低,弹性模量没有增加,依然与"骨置换"材料要求所匹配。     

基于民族传统文化的平面设计模数体系的构建研究

现代设计普遍存在功能至上,千篇一律,随着经济的发展生活节奏的加快,以及西方设计思想的渗入,致使现代设计普遍存在形式上的模仿,内容上空乏,忽视了华夏五千年的历史文明,中国传统民族文化历史源源流长,对现代设计的发展有极其重要的影响,把传统民族文化在利用到现代设计中显的至关重要.形成一定的规范秩序化的体系是现代设计的重要需求.     

Nanoindentation Measurements of the Mechanical Properties of Ni Thin Films: Effects of Film Microstructure and Substrate Modulus

This paper presents the results of nanoindentation measurements of the hardness and moduli of normally and obliquely deposited nanocrystalline Ni films on substrates of SiO₂, Si, and bulk Ni. Following an initial characterization of film microstructure and surface topography with atomic force microscopy (AFM), the paper examines the effects of film microstructure, film thickness, and substrate modulus on the measured film mechanical properties. Obliquely deposited films are shown to have lower hardness values than normally deposited films. The measured hardness values and material pile-up are also shown to depend significantly on the mismatch between the film modulus and substrate modulus. A framework is presented for quantifying the effects of substrate modulus mismatch on basic film mechanical properties.     

杆式支撑换热器换热的数值模拟

采用数值模拟方法研究杆式支撑换热器．可以克服实验研究方式的不足。利用相似理论确定数值模拟模型,分析了各结构参数变化对换热器传热和流动性能的影响．利用最小二乘法．进一步回归出杆式支撑换热器层流下的传热和流动阻力的准数关联式．设计,建造了一套可变结构参数的杆式支撑换热器热模实验装置．在壳程单排管间布杆或双排管间布杆、不同流速和不同折流栅结构参数情况下测得了100个实验值．将实验测量值和计算值进行了比较。结果表明：数值模拟计算的Nu值和△p值与实验测量值吻合很好,由实验数据回归得到的传热和流动阻力无因次准数关系式与数值模拟程序计算得到的准数关系式也吻合较好．显示出数值模拟方式进行换热器研究的显著优点.     

Development of carrot parenchyma softening during heating detected in vivo by dynamic mechanical analysis

Dynamic mechanical analysis was employed to explore the development of carrot parenchyma softening during heating in the range of 30–90 °C. Results indicated that compared with raw carrots the toughness of carrots at 60 °C decreased significantly (P < 0.05) at 0.5 °C/min while there was no significant deference (P > 0.05) at 2 °C/min. Samples at 0.5 °C/min finally obtained the lower toughness. Besides, both loss tangent (LT) and two negative peaks on the temperature–slope plot were heating rate dependent. At 0.5 °C/min, distinct increases of LT started at about 48 °C while at about 67 °C at 2 °C/min. With increasing rate, LT effect decreased obviously. Increasing rates caused a shift of both peaks from low temperatures (49–60 °C) to high ones (67–75 °C). Values of both peaks were significantly higher (P < 0.05) at 0.5 °C/min than at 2 °C/min. Furthermore, the microstructure of samples at 0.5 °C/min was more rigid and irregular shrinkage, accompanied by more small pores as well as bigger cracks in comparison to that at 2 °C/min. And cell walls of samples at 0.5 °C/min seemed to thinner. Therefore, the development of carrot parenchyma softening during heating was both temperature and heating rate dependent. We suggested that the breakdown of pore proteins and middle lamella in cell walls induced the dramatic loss of cell turgidity and the subsequent changes of elastic modulus, collectively causing tissue softening.     

基于区域清晰度的纺织纤维图像融合

针对多焦面纺织纤维图像,提出一种基于区域清晰度的图像融合方法。用像素点灰度的模值衡量像素点的清晰度。首先通过对多焦面图像搜索像素点最大模值的方法,确定每个最清晰像素点(即灰度的模值最大)所在的图层号,并保存在图层号矩阵中。再针对图像中的噪声干扰,根据局部区域模值的最大值,确定区域阈值进行去噪处理,并修正图层号矩阵。然后根据图层号矩阵,用对应图层像素点的灰度值合成得到多焦面融合图像。最后对融合方法提出改进措施,以进一步提高图像处理的速度。实验表明所提出的多焦面图像融合方法行之有效。     

Poroelastic PEM fuel cell catalyst layer and its implication in predicting the effect of mechanical load on flow and transport properties

This study experimentally and numerically investigates the polymer electrolyte fuel cell (PEFC) catalyst layers (CLs) to analyze the coupled pore-fluid diffusion and resultant stress distribution. In the study, effect of nanoporosity on mechanical strength is explored by analyzing the CL structure based on the elastic modulus and the yield strength scaling laws of open-cell foams. A finite element analysis of the CL is performed by adopting the biphasic consolidation theory. The biphasic theory in combination with the transient consolidation principle of a porous body is formulated to account for the variation in the external loading conditions as well as the internal pore pressure. The CLs are observed to have the elastoplastic ionomer matrix and anisotropic nanoporosity, which are responsible for the localized plastic densification on indentation. The indentation behavior of the CLs appears to respond similar to the conventional low-density nanoporous foams leading to the localized nonlinear response of contact stiffness. The mechanical properties were found to be insensitive to the constituents’ (Pt and Carbon) concentration gradation over the CL thickness. In the numerical results, effect of porosity loss on the transport properties is discussed to highlight the importance of estimating the stress levels. It is outlined from the present study that under critical loading conditions, the yield limits of the CL play a crucial role in estimating the extent of transport losses. The effective proton conductivity and oxygen diffusivity losses are dependent on the macroscopic strength of the ionomer and the effective electronic conductivity loss is a function of intrinsic strength of the CL, which is also responsible for the overall durability of the CL.