Untersuchungen über den Wärmeübergang zwischen Block und Kokille beim Erstarren von Stahl

Messung des Wärmeübergangs zwischen Block und Kokille beim Erstarren von steigend vergossenen 1,4-t-Stahlblöcken aus beruhigtem unlegiertem Stahl bei Erfassung der Temperaturverteilung in der Kokille, der Oberflächentemperatur des Blockes, der Temperaturen in der festen und flüssigen Phase sowie des Zeitpunktes der Luftspaltbildung. Angaben über den Abbau der eingebrachten Überhitzung von rd. 50 °C. Aussagen über die Wärmeströme, die abgeführten Wärmemengen und über ein vereinfachtes Erstarrungsgesetz. Darstellung der Abweichungen vom √t-Gesetz. Ermittlung von Wärmeübergangskoeffizienten für verschiedene Stellen des Blockes in Abhängigkeit von der Erstarrungszeit. Erörterung des Mechanismus des Wärmeübergangs zwischen Block und Kokille.     

Idiopathic membranous glomerulonephritis

The only case of idiopathic membranous glomerulonephritis seen out of 106 nephropathic patients biopsied in the two last years at the C. H. 20 de Noviembre, I.S.S.S.T.E., is reported. Twenty-six showed nephrotic syndrome not associated to systemic disease, including the present case, which gave us an incidence of 3.8% of this entity. We were impressed by the low frequency of this disease, so we made a statistical epidemiological analysis localizing it geographically based on the available medical literature. On comparing the results of these studies we confirmed that this disease is significantly low in our environment.     

An analysis of learned helplessness: Continuous changes in performance, strategy, and achievement cognitions following failure.

Helpless children show marked performance decrements under failure, whereas mastery-oriented children often show enhanced performance. Current theories emphasize differences in the nature of the attributions following failure as determinants of response to failure. Two studies with 130 5th-grade children explored helpless vs mastery-oriented differences in the nature, timing, and relative frequency of a variety of achievement-related cognitions by continuously monitoring verbalizations following failure. Results reveal that helpless children made the expected attributions for failure to lack of ability; mastery-oriented children made surprisingly few attributions but instead engaged in self-monitoring and self-instructions. That is, helpless children focused on the cause of failure, whereas the mastery-oriented children focused on remedies for failure. These differences were accompanied by striking differences in strategy change under failure. The results suggest that in addition to the nature of the attribution one makes, the timing or even occurrence of attributions may be a critical individual difference. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

优化Lyocell工艺中纤维素溶解工序

瑞士List公司进一步优化了在1992年推出的纤维素溶解技术,可将各种廉价原料生产出优质的纺丝液.这种纺丝液可用于生产短纤、长丝和薄膜.     

Adhesive properties of asphalts and aggregates in tropical climates

In Central and South America, pavement deterioration due to moisture is high. The deterioration is directly related to the compatibility between the asphalt and aggregates, as well as the cohesiveness of the asphalt matrix. The affinity between these materials affects how well the bond will behave in the presence of water, and therefore the susceptibility of the asphalt mixture to moisture in the long term. It is well accepted that traditional tests for assessing moisture damage are not necessarily representative of high moisture conditions, such as those present in Colombia and Costa Rica. Therefore, it is imperative that methods to quantify the actual moisture susceptibility of hot-mix asphalt be adopted and implemented in local specifications. In order to characterise the true adhesion properties of regional materials, both physicochemical and mechanical analysis has been implemented to determine the moisture susceptibility of different binder–aggregate combinations typically used in Costa Rica and Colombia. The effect of antistrip additives on the water resistance of such combinations was also evaluated. The asphalt bond strength test was applied to mechanically determine the adhesive and cohesive strength of the binder–aggregate pairs. In addition, the measurement of physicochemical properties such as surface free energies of aggregates and binders allowed the determination of work of adhesion, cohesion and debonding of asphalt from the aggregate surface in the presence of water. A correlation between the physicochemical and the mechanical properties was found for most of the cases.     

维修工程系统——维修功能的演化机遇（续）

下图(图4)是维修工程过程的示意图。整个过程基本上可以分为以下几个步骤:第1步:系统逻辑配置。对生产设备的功能、辑和影响进行分析。第2步:数据。有两种获取数据的方法。第一是通过对设备功能的历史数据分析,第二是通过标准或者制造商的说明来获得数据。第3步:寿命周期费用决     

Characterization of heterogeneity in concrete and cement by mechanical spectroscopy

We propose a method to obtain the degree of heterogeneity of samples of cement or concrete due to the presence of cracks, bubbles or simply the native ingredients of the material. A number of samples are prepared in a cylindrical shape, and their transverse vibration resonant frequencies are measured. A given mode of oscillation will correspond to slightly different frequencies in different samples due to the random nature of the system. For example, for a given mixing formula, the ratio of sand to cement may be known, but the precise position of sand grain cannot be determined. We studied the statistical distributions of frequencies for each mode and found that there exists a relationship between the width of the probability functions and the degree of heterogeneity.     

维修工程系统——维修功能的演化机遇

世界上的各知名公司始终面临着不断提高竞争力以确保其在全球市场上占有一席之地这样的问题。在这种挑战中,维修功能尽管只是服务于产品,却扮演着一个基础性的角色,因为它通过对生产力(全球成本下降)、系统灵活性(面向顾客的适应性)和人性因素(环境和人的考虑)的影响而对竞争力产生直接的影响。为了满足这些新的需求,产品的维修必须产生质的跨跃,这种跨跃是由以干预为中心向以预防为中心的职能演化来带动。