On-line corrosion monitoring in geothermal district heating systems. II. Localized corrosion

Corrosion monitoring in district heating systems has traditionally been performed by using off-line methods, such as weight loss. The disadvantage is that the method is very slow, especially in low-corrosive environments, and that it only provides information about the past corrosion (accumulated over period of time). The purpose of the work is to test on-line monitoring methods in geothermal hot water in the district heating system in Reykjavik, Iceland. Geothermal water poses certain problems with regards to corrosion monitoring due to low conductivity, high pH and the presence of sulphide. These conditions make the geothermal environment low corrosive. However, a quality control is needed, especially since the sulphide causes the steel pipes to be more vulnerable towards localized corrosion. The methods used in this study were: linear polarization resistance (LPR), harmonic analysis (HA), electrochemical noise (EN) and zero resistance ammetry (ZRA). The Pitting Factor was measured with EN and showed promising results for measuring-localized corrosion on-line. A crevice corrosion cell also gave good results but had a low lifetime. However, the results of a galvanic corrosion cell (Fe/Cu) proved more difficult to interpret since they were dependent both on the dissolved oxygen and the sulphide level.     

Where is the psychology going? Structural fault lines revealed by psychologists' use of Kuhn.

Psychologists' appropriation of language and ideas from Thomas Kuhn's (1962, 1970b) The Structure of Scientific Revolutions reveals deep and contradictory concerns about truth, science, and the progress of the field. The author argues that psychologists, uncomfortably straddling natural and social science traditions, reference Structure for 2 reasons largely overlooked: first, because it presents an intermediate, naturalistic position in the war between relativist and rationalist views of scientific truth, and second, because it presents a psychologized model of scientific change. The author suggests that the history of this mutual influence--psychologists being influenced by Kuhn and vice versa--may usefuly inform current practices of psychological science. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The stiffness matrix in elastically articulated rigid-body systems

Discussed in this paper is the Cartesian stiffness matrix, which recently has received special attention within the robotics research community. Stiffness is a fundamental concept in mechanics; its representation in mechanical systems whose potential energy is describable by a finite set of generalized coordinates takes the form of a square matrix that is known to be, moreover, symmetric and positive-definite or, at least, semi-definite. We attempt to elucidate in this paper the notion of “asymmetric stiffness matrices”. In doing so, we show that to qualify for a stiffness matrix, the matrix should be symmetric and either positive semi-definite or positive-definite. We derive the conditions under which a matrix mapping small-amplitude displacement screws into elastic wrenches fails to be symmetric. From the discussion, it should be apparent that the asymmetric matrix thus derived cannot be, properly speaking, a stiffness matrix. The concept is illustrated with an example.     

热镀钢丝膜层的冷凝计算

分析了热镀钢丝自液池引出过程中的热传导，得出了温度分布的解析解，从而计算钢丝表面膜层达到凝固温度时的提抽高度，为结构设计及确定冷却装置的合理位置提供依据。     

短周期超晶格AlP／GaP能带结构的转变及其带间的光跃迁

介绍了间接跃迁的半导体ＡｌＰ与ＧａＰ形成的超晶格，由于零折叠效应，实现了能带由间接带隙向直接带隙的转变，从而增加了带间的光跃迁几率，并推导了该几率的表达式。     

高速钢W6Mo5Cr4V2的脱磷试验

在３０ｋｇ感应炉上用ＣａＯ－Ｎａ２ＣＯ３－ＣａＦ２－ＦｅｘＯ（ＭｏＯ３）渣、ＭｏＣｌ６粉剂和Ａｌ－Ｃａ合金作脱磷剂对高速钢Ｗ６Ｍｏ５Ｃｒ４Ｖ２进行脱磷试验。结果表明，ＣａＯ－Ｎａ２ＣＯ３－ＣａＦ２－ＦｅｘＯ渣的脱磷效果最好，一般脱磷率可达２６％￣５６％。     

二阶A型Cooper变换的增强型

对二阶Ａ型Ｃｏｏｐｅｒ变换进行增强，放宽可用性条件，并证明了其正确性，最后举例说明其应用。     

钢带捆扎对木箱强度的影响

从力学角度分析了钢带捆扎对木箱强度的影响，指出木箱经钢带捆扎后，可减小箱底的最大弯矩，提高木箱的承载能力和减少板厚。同时还在无支撑间隔的基础上，详细介绍了钢带捆扎的设计方法。     

军用滑木箱的设计分析

介绍了按日本标准设计的横板式和国内竖板式军用滑木箱的结构设计参数，从木箱抗弯、抗静压及顶盖抗弯三方面对比了两种木箱的力学性能，分析了两种木箱的特点及适用范围。     

Cr12钢的预处理工艺研究

本文研究了Ｃｒ１２钢经４种不同的预处理工艺处理后钢中碳化物的大小，数量，分布及钢的硬度，强度和韧性，试验结果表明，经调质处理，高温固溶淬火＋高温退火处理后，Ｃｒ１２钢中碳化物的大小，分布及其组织，性能均优于常规球化退火预处理的。通过扫描电镜对冲击断口的分析，初步探讨了新的预处理工艺提高韧性的原因。