Casting process and comparison of the properties of adapted load-sensitive magnesium alloys

Magnetic magnesium alloys can be utilized as a load sensitive material, in which the inverse magnetostrictive effect is used in order to measure the actual loads in structural components manufactured from such lightweight sensor alloys. To achieve a material which exhibits magnetic properties, Mg is alloyed with ferromagnetic materials like cobalt or samarium-cobalt. Alloying elements commonly used with Mg are utilized to improve the mechanical properties of these alloys, which however may have a slight negative impact on the magnetic sensitivity. In this work, two separate magnetic Mg alloys are compared, each with properties matched to the opposing requirements: (a) high load sensitivity and (b) satisfactory mechanical properties, respectively. The precipitation behavior of the ferromagnetic constituent Co in Mg together with other alloying elements is shown on the basis of SEM images. In addition, the dissolving behavior of the Co powder during the casting process of a binary Mg–Co alloy is investigated. Cyclic loading tests employing harmonic analyses of eddy current signals are utilized in order to verify the alloys’ sensory properties. The mechanical properties are investigated using tensile tests.     

A note on the success ratio and the utility of fixed hiring rate personnel selection decisions.

Using simple simulation methods, the author verifies that the formulas used to estimate both the expected success ratio of a selection and the expected average criterion score of the selectees overestimate the real gain one may expect to obtain when hiring a preestablished proportion of employees from a finite sample of applicants. To correct for this deficiency, the present article shows how an exact estimate of the expected payoff can be obtained. In addition, it indicates how the new approach can be used to assess the sampling variability of the utility estimates. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Anwendungsorientierung im Informatikstudium

Ohne Zusammenfassung     

Forum The built environment through the cultural–architectural lens

The Building Research & Information special issue ‘Developing Theories on the Built Environment’ (36(3) 2008) raises the question of whether there could be a common framework to combine a wide range of interests and provide insightful answers. This commentary explores the significance of cultural contexts for theories on the built environment. Deficiencies in both architectural theory and history have left cultural associations and values inarticulated. Increasingly, architectural theory and history have become marginalized in the widening debate about the built environment as their focus has become too limited and separated from everyday and urgent needs. The cultural ‘footprint’ remains the strongest force and determines patterns of behaviour and expectations. It is argued that a cultural lens is the primary key in providing both insight into an ideal and consciousness of (intellectual and practical) habits influencing our actions. In order to grasp the complexity of the built environment and provide a useful model for altering our collective actions, it is vital to study the transformational chains, for example, from the cultural to the ecological.

Ce numéro spécial de Building Research & Information consacré aux théories de développement du milieu bâti (volume 36(3), 2008) pose la question de la création possible d'un cadre commun capable de combiner une grande palette d'intérêts et de fournir des réponses intuitives. Cet article analyse le sens des contextes culturels de théories relatives au milieu bâti. Les lacunes que l'on constate dans la théorie et dans l'histoire de l'architecture n'ont pas permis d'expliquer les valeurs et les associations culturelles. De plus en plus, la théorie et l'histoire de l'architecture ont été marginalisées dans le débat qui s'élargit sur le milieu bâti car leurs points d'intérêt sont devenus trop limités et à l'écart des besoins quotidiens et urgents. L'empreinte culturelle demeure la force la plus importante et détermine les tendances de comportement et des attentes. On prétend qu'une loupe grossissante de la culture est la clef principale pour fournir à la fois un idéal et une conscience des habitudes (intellectuelles et pratiques) ayant une influence sur nos actions. Pour saisir la complexité du milieu bâti et fournir un modèle utile en vue de modifier nos actions collectives, il est essentiel d'étudier les chaînes transformationnelles, par exemple, de la culture à l'écologie.

Mots clés: théorie de l'architecture, milieu bâti, cadre conceptuel, sagesse pratique, formulation de théories, elaboration de théories     

Design von pulverförmigen und granularen Waschmitteln

In the last fifty years, powder and granular detergents have been significantly improved in performance and ecology: more concentrated (less chemicals), biodegradable surfactants, no phosphates, reduced water and energy consumption. The use of optimized enzymes and bleaching boosters enables lowered wash temperatures and the removal of natural stains. The production of solid detergents runs either in spray towers without and with compaction step, or in a non‐tower agglomeration plant. The latest generation of granulation with an integrated mill for simultaneous drying and grinding allows the production of spherical particles, which can be adjusted (small or large, heavy or light). Future formulations will enable lower washing temperatures.     

Dynamic behavior of nanometer-scale amorphous intergranular film in silicon nitride by in situ high-resolution transmission electron microscopy

We report about the dynamic behavior of a nanometer-scale amorphous intergranular film (IGF) in a Si₃N₄ ceramic by an in situ heating experiment in a high-resolution transmission electron microscopy (HRTEM). During the experiment the IGF gradually vanishes at 820 °C accompanied by the formation of crystal planes within the IGF. The IGF reappears after cooling back to room temperature. The results cannot be explained within the framework of a force balance model. We argue that the dynamic behavior of the IGF in our experiment originates from the open system observed.