Model Driven Architecture

Bei der Model Driven Architecture (MDA) bilden Modelle die zentralen Elemente des Softwareentwicklungsprozesses. Ziel ist es, plattformspezifische Modelle möglichst automatisiert aus plattformunabhängigen Modellen abzuleiten. Dadurch soll der Aufwand der Softwareentwicklung verringert und die Adaptierung an neue Technologien erleichtert werden.*Vorschläge an Prof. Dr. Frank Puppe oder Dieter Steinbauer Alle „Aktuellen Schlagwörter“ seit 1988 finden Sie unter: www.ai-wuerzburg.de/as     

A survey of the training of computer users in Swedish companies

This study concerns how user training on newly introduced computer application programs is carried out. Questionnaire data from the computer managers of 265 Swedish companies were analysed. The results show that formal training, i.e., teacher-directed group instruction, and self-studies using instruction manuals represented nearly two-thirds of all reported training forms. For the most recently introduced program, classes (group instruction) with simultaneous computer exercises was the form of formal training that was nearly always used. When formal training was given it was compulsory in over half of the cases. However, substitutes for users attending a training course were only provided by the company in very few of these cases. The implications of these findings for effective user training are discussed.     

Controlled undercooling of liquid iron in contact with ZrO2 and MgO substrates under varying oxygen partial pressures

The objective of this study is to determine the conditions under which the inclusions present in liquid steel can act as heterogeneous nucleants for solidification. In order to study the factors that define the undercooling of a given metal/oxide couple, the undercooling of a pure iron sessile droplet in contact with Al₂O₃, ZrO₂, and MgO substrates was measured under controlled oxygen partial pressures by observing droplet recalescence. The results showed that the undercooling of iron, in contact with a particular substrate, did not have a unique value, but was significantly affected by the oxygen content on the gas phase. For oxygen partial pressures between 10⁻²¹ and 10⁻¹⁹, the undercooling of iron on ZrO₂ substrates was stable and around 290 °C. In the same range of oxygen partial pressure, the undercooling of iron on MgO substrates remained below 100 °C due to the low stability of this oxide. At lower oxygen contents, substrate decomposition might be the cause for the observed drop in the undercooling of iron on ZrO₂ substrates to below 100 °C. The undercooling also decreased for increasing oxygen content as verified when the gas was changed from gettered Ar/Ar-H₂ to CO/CO₂ mixtures. The variation in undercooling was related to the wetting of the substrate by the liquid metal, where the deep undercooling observed in the ZrO₂ experiments occurred when the highest contact angle between the liquid metal and the substrate was achieved.     

IPv6 delay and loss performance evolution

Although packet delay and loss are two important parameters of the Internet performance, to the best of our knowledge, the evolution of large‐scale IPv6 delay and loss performance has previously not been studied. In this paper, we analyze more than 600 end‐to‐end IPv6 paths between about 26 testboxes of RIPE Network Coordination Centre over two years, and compare the delay and loss performance over time with their IPv4 counterparts. We present and discuss the measurement methodologies and show that IPv6 paths have a higher delay and loss than their IPv4 counterparts. The main reason for the worse performance stems from IPv6‐in‐IPv4 tunnels rather than from native IPv6 paths and such tunnels are still widely used today. Copyright © 2007 John Wiley & Sons, Ltd.     

Factor structure of the SOCRATES in a clinical sample of adolescents.

This study investigated the Stages of Change Readiness and Treatment Eagerness Scale (SOCRATES: W. R. Miller & J. S. Tonigan, 1996) in adolescents presenting for treatment of alcohol use disorder (AUD). The participants were 80 males and 43 females (mean age=16.8 years) who presented for AUD treatment (95.1% outpatient, 4.9% inpatient). Participants completed assessments at baseline and 1 year and provided information on alcohol use and related variables monthly between these 2 assessments. Principal-components and confirmatory factor analyses of the baseline SOCRATES identified 2 factors, Taking Steps and Recognition, which showed good internal consistency and concurrent and predictive evidence of validity. The results were interpreted as supporting the use of the SOCRATES with clinical samples of adolescents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

What do we know about innovation in nanotechnology? Some propositions about an emerging field between hype and path-dependency

This contribution formulates a number of propositions about the emergence of novel nanoscience and nanotechnology (N&N). Seeking to complement recent work that aims to define a research agenda and draws on general insights from the innovation literature, this paper aims to synthesize knowledge from innovation-related studies of the N&N field. More specifically, it is suggested that N&N is often misconstrued as either a field of technology or an area of (broadly) converging technologies while evidence to date suggests rather that N&N be considered a set of inter-related and overlapping about not necessarily merging technologies. The role of instrumentation in connecting the various N&N fields is underlined. Finally, the question is raised whether change in N&N tends to be incremental rather than discontinuous, being the result of technological path-dependencies and lock-ins in industry-typical search regimes that are only slowly giving way to more boundary-crossing activities.     

Isolation and Spectroscopic Characterization of Eu@C72

A new Eu-endohedral fullerene cage, namely, Eu@C₇₂, was synthesized, separated, and a single isomer, Eu@C₇₂-I, has been isolated by multi-step HPLC for the first time and characterized by LDI-TOF mass spectrometry, UV-Vis and EPR spectroscopy. Additionally, a second isomer, Eu@C₇₂-II, has been separated by HPLC and identified by LDI-TOF mass spectrometry.     

Degradation of Stiffness of Cemented Calcareous Soil in Cyclic Triaxial Tests

The deformation characteristics of artificially cemented calcareous soil subjected to undrained cyclic triaxial loading are investigated at different confining pressure and cyclic stress levels. The influence of cementation on the shear stiffness is investigated by comparing the behavior of cemented and uncemented soils with similar initial conditions. It is observed that the deviator stress and the deviatoric strain at yield reduced with increasing number of cycles for cemented sand due to progressive degradation of bond, which results in significant decrease in stiffness. On the other hand, a strain-hardening effect is observed in uncemented sand and this results in increasing yield stress and strain with progressive number of cycles. A linear relationship between degradation index and number of cycles is observed for cemented sand. This relationship has been synthesized in the form of an empirical equation by modifying a previously proposed equation for cohesive soils. This empirical equation was further used to evaluate the fatigue life of soils by adopting a failure criterion.     

Failure of a stationary pump engine piston

Piston failures are not a common occurrence, but they do occur, and failure is usually associated with fatigue crack growth. Most failures initiate at the gudgeon pin hole or in the skirt of the piston. Occasionally they fail elsewhere. In the example covered in this paper, failure initiated in the crown and progressed down to the gudgeon pin before final failure occurred. This paper outlines the cause and mode of failure and shows that small metallurgical discontinuities can contribute to these failures under the right circumstances.