High temperature tensile testing of ceramic composites

The various components of a high temperature tensile testing system are evaluated. The objective is the high temperature tensile testing of SiC fiber reinforced reaction bonded Si3N4 specimens at test temperatures up to 1650 C (3000 F). Testing is to be conducted in inert gases and air. Gripping fixtures, specimen configurations, furnaces, optical strain measuring systems, and temperature measurement techniques are reviewed. Advantages and disadvantages of the various techniques are also noted

Optical strain measuring techniques for high temperature tensile testing

A number of optical techniques used for the analysis of in-plane displacements or strains are reviewed. The application would be for the high temperature, approximately 1430 C (2600 F), tensile testing of ceramic composites in an oxidizing atmosphere. General descriptions of the various techniques and specifics such as gauge lengths and sensitivities are noted. Also, possible problems with the use of each method in the given application are discussed

Effect of stress on ultrasonic pulses in fiber reinforced composites

An acoustical-ultrasonic technique was used to demonstrate relationships existing between changes in attenuation of stress waves and tensile stress on an eight ply 0 degree graphite-epoxy fiber reinforced composite. All tests were conducted in the linear range of the material for which no mechanical or macroscopic damage was evident. Changes in attenuation were measured as a function of tensile stress in the frequency domain and in the time domain. Stress wave propagation in these specimens was dispersive, i.e., the wave speed depends on frequency. Wave speeds varied from 267,400 cm/sec to 680,000 cm/sec as the frequency of the signal was varied from 150 kHz to 1.9 MHz which strongly suggests that flexural/lamb wave modes of propagation exist. The magnitude of the attenuation changes depended strongly on tensile stress. It was further observed that the wave speeds increased slightly for all tested frequencies as the stress was increased

Enterprise Change: Improving Complex Enterprises with System Models

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From Breaking Bad to Worse: Exploiting Homologous DNA Repair Deficiency in Cancer

DNA repair deficiencies are common among cancer cells and represent a potential vulnerability that might be exploited by targeting compensatory repair pathways. However, the identification of synthetically lethal combinations of DNA repair defects, although of significant clinical relevance, has been somewhat anecdotal. Although numerous models have been proposed to explain synthetic lethality among DNA repair mutations, we have only a limited understanding of why a given mutation should render cells sensitive to another. In this issue of Cancer Discovery, Dietlein and colleagues define a general connection between mutations in genes involved in homologous recombination and sensitivity to inhibitors of non-homologous end joining. In doing so, they provide a mechanism to demarcate a set of seemingly diverse tumors that may be highly responsive to established DNA repair–targeted therapeutics

Enterprise Change

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Life as Game: A Theory Elaboration

Throughout history, individuals and groups have attempted to manage how they are seen in the public eye. People usually play interaction games with their audiences in order to make themselves appear more positive and desirable. Some cases, however, include individuals or groups who do not want to fit in, and who do not want to appear desirable. This analysis examines Goffman\u27s theory of impression management with the metaphor, ltfe as game.The theory is applied to two cases of differing orgatizational level-an individual, Malmard James Keenan, and a large, complex organization, the R. J. Reynolds Tobacco Company. Theory elaboration is an integral part of studying social theories. When new social groups, patterns, or norrns emerge, new ways to think about society must be introduced. Theory elaboration is, according to Vaughan, the process of refining a theory, model, or concept in order to specify more carefulty the circumstances in which it does or does not offer potential for explanation. Theory elaboration allows social theories to remain relevant and applicable to the societies in which they were created. Some consider that, the examination of data with theory elaboration as the goal is seen. . . as a major (if not the major) building block of a positive science. Therefore, the Evaluation and Elaboration sections of this essay depart from the application of Goffman\u27s ideas and examine his theory for holes or insufficiencies, so that new definitions may be created to increase the relevance of life as game to societal interaction. Through a comparative case analysis, it is discovered that Goffman\u27s theory must be elaborated upon to include a definition of a team metaphor, instead of only describing individual interaction; room must also be made for individuals whose motivation is not to gain advantage by appearing desirable to an audience

Der grüne Rettungsring, Mit vernetzter Steppenbegrünung der Klimakrise global begegnen von Lorenz Hübner

Großflächige Vegetation hat in heiß-trockenem Klima eine doppelte klimaschützende Wirkung: durch die Senkung des CO2-Gehalts in der Atmosphäre und als direkter lebensförderlicher Klimafaktor. Bisher kaum beachtet könnte es global für niedrigere Temperaturen und ausgeglichene Niederschläge sorgen wenn es gelingt, ausgedehnte Steppenbegrünungen in Form eines »grünen Rettungsrings« um die Wüsten der Erde zu legen. Heiße, austrocknende Winde können so abgefangen, Landwirtschaft vielerorts wieder ermöglicht werden. In diesem lesenswerten Büchlein werden erste Klimadaten von den weltgrößten Begrünungsprojekten und eine Vielzahl konkreter Maßnahmen vorgestellt, die zeigen, wie wir mit Vegetation als Makro-Klimafaktor der Klimakrise begegnen können.Lorenz Hübner, promovierter Immunbiologe, wurde schon in seiner Jugend von Bildern der Dürre und des Hungers im Sahel geprägt. Seit Mitte der 1970er-Jahre verfolgte er Wiederbewaldungs- projekte. Durch den Kontakt mit Entwicklungshelfern in Mali wurde ihm klar, wie wichtig der Austausch von Information und Praxiswissen für diese und andere Regionen ist. Um diesen zu unterstützen, hat er sich der Zusammenstellung der Ergebnisse der bereits existierenden »Great Green Walls« angenommen.Das Buch hat die 12 Kapitel: 1. Einleitung, 2. Regionaler Klimafaktor Vegetation, 3. Vernetzung stabilisiert Ökosysteme, 4. Klimaerwärmung durch zusätzlichen Wald? 5. (Wieder)Bewaldung für Regionalklima und CO2-Senkung, 6. Sahelzone, 7. Vegetation des Sahel nach der Dürre, 8. Der GGW im Sahel heute, 9. Wüstenbewaldung, 10. Globale Steppenbegrünung, 11. Politischer Wille, internationale Partnerschaft mit den GGWs,12. Zusammenfassung, Link-Sammlung, Literatur und Quellen, sowie Glossar, Abkürzungen zum Schluss. Eingeschoben ist ein Interview mit Prof. Dr. Klaus Becker, ehemals Professor an der Universität Hohenheim, zur Bedeutung der Vegetation als Klimafaktor in heiß-trockenen Regionen.GGW „Great Green Walls“, die Lösung für die Klimakrise? Ökologie und Meteorologie sind sich darin einig, dass Vegetation generell nur einen lokal-klimatischen Effekt hat. Neben der klimatischen Rendite gibt es aber eine nicht zu unterschätzende ökonomische und soziale Rendite, die nicht nur für die jeweilige Region, sondern auch weltweit von Bedeutung ist. Es geht um die globale Temperatur, die globale Ausgeglichenheit der Niederschläge und die globale Bodenfruchtbarkeit, wir sitzen alle in einem Boot.Somit sind für die Umsetzung des Vorhabens, politischer Wille und internationale Partnerschaft, nicht nur der betroffenen Länder, gefragt. Es gibt erste Erfolge des GGW-Projektes, aber die große Umsetzung fehlt noch. Dies bedarf jahrzehntelanger Bemühungen, Projekte in Algerien und China zeigen dies. Ein Verdienst des Autors ist es, Wege dazu aufgezeichnet zu haben. Hervorzuheben ist die Widmung des Buches für Tony Rinaudo, Träger des Right Livelihood Awards 2019, der mit seiner vorbildlichen Arbeit schon vielen Menschen im Sahel die Landflucht ersparte und ein Überleben in Eigenständigkeit ermöglichte. Insgesamt ist das Buch ein Werk, dem man besonders auch auf politischer Ebene, Erfolg wünscht

The West Dallas Gang: a screenplay

During the war on crime of the 1930s, Texas officers had done their fair share when they brought down the infamous Bonnie and Clyde. Yet, two months after the ambush, members of the gang were once again on the loose after a daring prison escape. The West Dallas Gang follows Dallas Deputy, Ted Hinton, who is determined to arrest these last members, and to right the wrongs he feels are attached to the ambush of Bonnie and Clyde. At the same time, Hinton crosses several lines in his investigating process that could ultimately jeopardize his career and his marriage. It is his relationship with Clyde\u27s family, and familiarity with the Dallas underworld, that give him the edge over other officers. Hinton is labeled a hero, but it is not the approval of the community that he seeks

High Temperature Mechanical Behavior of Ceramic Matrix Composites

The research accomplishments under this grant were very extensive in the areas of the high temperature behavior of ceramics, ceramic composites and testing standards for these materials. Rather than try to summarize all this research I have enclosed research papers and reports which were completed with the funding provided by the grant