High-Throughput Nanoindentation for Statistical and Spatial Property Determination

Standard nanoindentation tests are “high throughput” compared to nearly all other mechanical tests, such as tension or compression. However, the typical rates of tens of tests per hour can be significantly improved. These higher testing rates enable otherwise impractical studies requiring several thousands of indents, such as high-resolution property mapping and detailed statistical studies. However, care must be taken to avoid systematic errors in the measurement, including choosing of the indentation depth/spacing to avoid overlap of plastic zones, pileup, and influence of neighboring microstructural features in the material being tested. Furthermore, since fast loading rates are required, the strain rate sensitivity must also be considered. A review of these effects is given, with the emphasis placed on making complimentary standard nanoindentation measurements to address these issues. Experimental applications of the technique, including mapping of welds, microstructures, and composites with varying length scales, along with studying the effect of surface roughness on nominally homogeneous specimens, will be presented.     

地震时坝面散粒体跃移距离的估计

本文讨论了当地材料坝在强震作用下的两种损伤形态和斜面上散粒体的起始滑动加速度,证实了颗粒在坝面上跃移时所受的阻力基本上为0-2阻力,说明了估计地震时坝面颗粒总跃移量的方法和步骤。     

用于农残快速检测的离心式微流控芯片研制

基于酶抑制原理结合光度分析方法,研制一种预存储生化试剂的离心式微流控芯片。设计制作的一次性微流控CD芯片集成进样、酶抑制反应、显色反应及检测单元,结合自行研制的便携式分析装置,可以同时检测12个样品,能够实现对大批量农产品中有机磷和氨基甲酸酯类农药残留进行现场、快速、高通量检测。结果表明:与传统农残快速测定仪比较,微流控芯片农残速测系统操作单元集成度高,可以实现农残检测流程的自动化,样品及试剂消耗量降至传统速测方法的约1/20,同时检测灵敏度、重复性和准确性整体优于传统农残快速测定仪,可以满足基层非专业人员针对大批量样品农药残留的筛查需求。     

Nanotribologie: Messung von mechanischen Eigenschaften im Sub-Mikrometer-Bereich

Hardness of a material describes the resistance of a material under indentation by a solid body. The vickers hardness [1] is determined by loading a diamond pyramid with a known force that is in contact with a specimen. The length of the diagonal of the remaining indent is used to calculate the contact area. The ratio of force and contact area is the vickers hardness. The abilities of modern technique of measurement replace the optical analysis of each indent by calculating the hardness from force and displacement recorded during the indent. Nano-hardness measurements now can be used to determine the mechanical properties of thin films and structures in the range from less than 10 nm to 1μm. Hardness can be measured with very small indentations, which could not be analyzed according to vickers. Time dependent properties as creep and viscose flux of material can be checked on sub-micron scale. The technique of nano-hardness measurements is comparable to the universal hardness test [2] for metals, whose minimum indentation depth of h = 0.2 μm still is too big for many applications. Combined with an atomic force microscope (AFM) the presented technique is capable image the area of interest before and after testing. Mechanical properties like friction-constants and wear can be measured quantitatively. The indenter can be used as a micro-machining tool with high precision as well.     

急流冲击波简化式

本文在Ｉｐｐｅｎ冲击波理论的基础上推导得到新的冲击波简化式，在ＶｏｎＫａｒｍａｎ积分基础上建立了缓冲击波简化积分式．这两个简化式形式简单，适用范围广，便于应用．     

Kinematic CT of the patellofemoral joint

The relationship between time structure and procrastination was investigated among 115 Irish undergraduate students. Significant negative zero-order correlations were found among scores for all five subscales of time structure and procrastination. A follow-up stepwise multiple regression indicated a significant multiple correlation (R = .61) between all five time structure subscale scores and procrastination. Significant predictors of procrastination were scores on the Time Structure subscales of Effective Organization followed by Sense of Purpose. These results suggest that strategies focusing on time management in conjunction with existential approaches of psychotherapy may be an effective intervention for reducing procrastination.     

溴化锂制冷机的应用与节能效果

往复式氨压机是常用的制冷设备,但它的能耗较高,与此相比,本文介绍的吸收式溴化锂制冷机则具有热效率高,低能耗等特点。     

泄水建筑物过流壁面不平整体初生空化与空蚀研究述评

泄水建筑物过流壁面不平整体初生空化与空蚀的研究进展，本文作了扼要的综述与评论。内容包括不平整度的定义及其初生空化与空蚀的理论分析、试验研究、比尺效应和理论预测，以及尚存在的问题。文中也包括了作者在上述工作中所作的研究和相应的看法。     

端乙烯基水性聚氨酯乳液的合成研究

以甲苯二异氰酸酯(TDI)、聚丙二醇(N-210)为主要原料,二羟甲基丙酸(DMPA)为亲水扩链剂,l,4-丁二醇(BDO)为小分子扩链剂,甲基丙烯酸羟乙酯(HEMA)为封端剂,三乙胺(TEA)为中和剂合成了端乙烯基水性聚氨酯乳液.讨论了DMPA用量、中和度和R值对乳液的影响,得出了制备端乙烯基水性聚氨酯乳液的最佳配方.     

Cyclic Nanoindentation for Local High Cycle Fatigue Investigations: A Methodological Approach Accounting for Thermal Drift

Cyclic nanoindentation allows characterizing the influence of single phases and their interactions on fatigue mechanisms. Herein, a method for high cycle fatigue testing by nanoindentation is presented. By combining high- and low-frequency indentation modes, high cycle numbers are achieved while obtaining sufficient data points to reconstruct force–displacement hysteresis loops. A challenge is the stochastic course of thermal drift which is addressed by measuring drift rate in regular low-force holding segments. Drift rates are used to correct the displacement values, yielding reproducible cyclic deformation data as it is shown for two very different materials, a ductile metal and a brittle ceramic.