The influence of tempering on cleavage fracture stress and transition behaviour of bainitic 2.25Cr1Mo steel

The effect of tempering on the mechanical properties and on the cleavage fracture stress of bainitic 2.25Cr1Mo steel was studied in a variety of structures with the Hollomon-Jaffe parameter M ranging between 18.23 × 10³ and 21.70 × 10³. The rapid decrease in yield stress and UTS was observed up to value M = 20 × 10³. For values M > 20 × 10³ the reduction of yield stress and UTS slows down. The cleavage fracture stress continuously decreases with increasing value of M. Concurrently, the changes in dislocation density and in carbide size, morphology and distribution were observed. Various theories of cleavage origin of tempered bainitic microstructures are discussed. The transition temperatures, determined from impact Charpy test, reach minimum at M = 20 × 10³. Using Orowan's theory of initiation of the brittle fracture in steels, the minimum of transition temperatures may be explained by the different reduction rates of cleavage fracture stress and yield stress with value of M.     

Irreführende Leitbilder Zum Mythos der Individualisierung durch pharmakogenetische Behandlungskonzepte. Eine kritische Anmerkung

Zusammenfassung Die prospektive Analyse der ethischen Implikationen medizinisch-technischer Innovationen läuft immer auch Gefahr, sich in den Wunschbildern von Marketingexperten zu verfangen. Vor diesem Hintergrund könnte es durchaus nützlich sein, die Erkenntnisse der Wissenschafts- und Technikforschung zur Genese und Entwicklung neuer Techniken auszuschöpfen. Dies erscheint gerade auch für die ins Phantastische weisende Zukunft der Individualisierung medikamentöser Therapie, wie man ihr häufig in der Beschreibung pharmakogenetischer Behandlungskonzepte begegnet, angebracht. Techniken, die sich noch im Entwicklungsstadium befinden und deren breite Anwendung noch einige Jahre auf sich warten lassen wird, sollten sehr sorgfältig auf ihren Realitätsgehalt und das zu erwartende Leistungspotenzial hin analysiert werden. Dazu gehört v. a. auch eine kritische Auseinandersetzung mit den Leitbildern, Visionen und Nutzenversprechen, mit denen technische Innovationen oft sehr absichtsvoll ausgestattet werden. Wird dabei die Distanz zur Rhetorik der Protagonisten der neuen Techniken nicht gewahrt, gerät die ethische Reflexion unvermittelt in die Rolle, profane Marketingstrategien wortgewandt und ideenreich zu veredeln.     

Beyond imprisonment of meaning: Technology facilitating redefining

Defining is a natural and necessary response to an ambiguous world, but causes fixation of categories and perspectives. On the basis of two earlier studies of project groups, we came to argue that redefining, and hence constructing various ways in which one perceives and understands something, enables groups to overcome imprisonment in meaning, establishing continuous development and flexibility. In this article, we first build a rationale for facilitating a process of redefining, to be taken into account when designing technology. Departing from this rationale, we discuss features of groupware technology that permit change by being flexible, and evoke redefining by engaging the user more actively. In so doing, we argue to think along new lines in the design of communication and collaboration technology. This paper proposes a specific perspective on technology, facilitating groups to engage in a productive, creative fashion of exploiting meaning potential.     

Chemical composition of new copper alloys for machining and its effect on their susceptibility to corrosion cracking

Zinc‐containing copper alloys, the so‐called α + β brasses, are commonly used in contact with potable water. These materials are alloyed with lead to improve machinability. In wrought special brass alloys, reducing the content of this alloying element or replacing it with alternative alloying additions may give rise to a new type of machinable copper alloys which differ from the original alloys by their contents of other modifier elements such as Si (or possibly, Mg, Bi, and P). These alloys have a very low content of lead required for the break‐up of chips during machining. Even though these types of brass exhibit a very good machinability, the effects of their chemical composition on the resistance of the alloy to corrosion cracking have not yet been given sufficient attention. This paper aims to present an assessment of three new types of machinable copper alloys regarding their susceptibility to stress corrosion cracking, in comparison to that of the lead‐alloyed variety, in 0.05 M NaCl, NaNO₂, and Na₂SO₄ solutions. The slow strain rate test has been used for this purpose, and its results were correlated with metallographic evaluation of the number and depth of the cracks observed on the test specimen surfaces on completion of the test.     

The combustion products of polymeric materials. III: GC–MS Analysis of the combustion products of polyethylene,polypropylene, polystyrene and polyamide

A series of gas chromatographic–mass spectrometric analyses was carried out on polyethylene, polypropylene, polystyrene and polyamide in CAB 4.5 and CAB 650 chambers in the flaming and non-flaming combustion mode. The combustion products formed were identified and used to characterize the combustion process in both chambers; procedures were selected for testing polymeric materials for the dangerous effects of their combustion products.     

OLED科技的未来最大功率效益的重要性

虽然最近几年有机发光二极管(Organic LjghtEmission Diode,OLED)显示器已经商品化,不过OLED显示器不论是发光效率、使用寿命,或是改用无晶硅基大型面板等问题仍有待改善.     

A taxonomy of variability realization techniques

Development of software product families relies heavily on the use of variability to manage the differences between products by delaying design decisions to later stages of the development and usage of the constructed software systems. Implementation of variability is not a trivial task, and is governed by a number of factors. In this paper, we describe the factors that are relevant in determining how to implement variability, and present a taxonomy of variability realization techniques. Copyright © 2005 John Wiley & Sons, Ltd.