Kinetische Untersuchungen zum Schwefelübergang zwischen kohlenstoffgesättigtem Eisen und CaO-SiO2-Na2O-Schlacken

Mechanismus und Kinetik des Schwefelüberganges vom Metall zur Schlacke. Messung der Schlackenviskosität während des Ablaufs der Entschwefelungsreaktion. Elektrochemische Untersuchungen der Vorgänge an der Phasengrenze. Deutung der Versuchsergebnisse durch elektrochemische Vorgänge zwischen Metall und Schlacke mit Differentialgleichungen.     

Die Phosphoraktivität im flüssigen Eisen und ihre Beeinflussung durch Nickel,Mangan und Chrom

Temperaturabhängigkeit des Gleichgewichtes von Phosphordampf mit flüssigem Eisen; Wirkungsparameter ?^P_P zwischen 1515 und 1650 °C; Beeinflussung der Phosphoraktivität im flüssigen Eisen durch Nickel, Mangan und Chrom; Phosphoraktivität im System Nickel-Phosphor. Phosphoraktivität im flüssigen an Kohlenstoff gesättigtem Eisen bei gleichzeitiger Anwesenheit von Silizium, Nickel, Mangan und Chrom.     

The design of technical artifacts with regard to work experience: The development of an experience-based documentation system for maintenance workers

The German discussion about experience-guided work has led to the question of how work experience can be regarded within the process of designing technical artifacts. This paper offers a solution for the area of skilled maintenance work. Some considerations about the nature of experience and about the problems skilled workers have in aquiring work competences within computer aided production environments are introduced in order to illustrate the design philosophy: A decision-support-system is described which stimulates workplace learning by enabling previous and present users of the system, including maintenance staff and shop floor workers, to exchange and build on experience.     

Zur Effektivität von Gradientenverfahren für Zuschnittprobleme

Zusammenfassung In dieser Arbeit werden diskrete Gradientenverfahren zur Lösung von ein-, zwei- und dreidimensionalen Zuschnittproblemen vorgeschlagen. Die Effektivität der Algorithmen wird an zwei Parametern gemessen: Arbeitsaufwand und Güte. Wir betrachten aus der Menge aller Lösungsalgorithmen für Zuschnittprobleme vernünftige Algorithmen und geben Güteabschätzungen für diese Klasse an. Eine Klasse eindimensionaler Zuschnittprobleme wird definiert, die zur Klasse P gehört.Unterstützt vom DAAD.     

Zur Querkraftgefährdung bestehender Spannbetonbrücken

Zur Formulierung einer Handlungsanweisung werden in Teil I die geänderten Lastannahmen für Brücken nach DIN Fachbericht 101 mit den Belastungsklassen nach alten Normen verglichen und gezeigt, wie anhand aktueller Verkehrszahlen die Lastansätze modifiziert werden können. Der aktuelle Brückenbestand in Hessen wird mit der Straßeninformationsbank (Teilprojekt Bauwerksdaten) ausgewertet, um Klassifizierungs‐ und Bewertungskriterien zu erarbeiten. Zur Beurteilung des Querkraftwiderstandes werden die Grundlagen der Querkraftbemessung nach DIN 1045, DIN 4227, DIN Fachbericht 102 und aus der Literatur gegenübergestellt. Shear‐Vulnerability of Existing Pre‐Stressed Concrete Bridges. Part One: Basics In Part I, to formulate an operation directive the revised load assumptions for bridges of DIN Technical Report 101 are compared with the loading classes according to old standards and it is demonstrated, how the loading models can be modified based on actual traffic data. The current bridge asset in the Federal State of Hesse is evaluated using the “Road Information Database (Sub‐Project: Structural Data)” in order to work out classification and evaluation criteria. Regarding the assessment of the shear load‐bearing capacity the fundamentals of the shear load design models of DIN 1045, DIN 4227, DIN TR 102 and from the literature are compared.     

Doping Molecular Monolayers: Effects on Electrical Transport Through Alkyl Chains on Silicon

n‐Si/C_nH_{2n + 1}/Hg junctions (n = 12, 14, 16 and 18) can be prepared with sufficient quality to assure that the transport characteristics are not anymore dominated by defects in the molecular monolayers. With such organic monolayers we can, using electron, UV and X‐ray irradiation, alter the charge transport through the molecular junctions on n‐ as well as on p‐type Si. Remarkably, the quality of the self‐assembled molecular monolayers following irradiation remains sufficiently high to provide the same very good protection of Si from oxidation in ambient atmosphere as provided by the pristine films. Combining spectroscopic (UV photoemission spectroscopy (UPS), X‐ray photoelectron spectroscopy (XPS), Auger, near edge‐X‐ray absorption fine structure (NEXAFS)) and electrical transport measurements, we show that irradiation induces defects in the alkyl films, most likely C?C bonds and C? C crosslinks, and that the density of defects can be controlled by irradiation dose. These altered intra‐ and intermolecular bonds introduce new electronic states in the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap of the alkyl chains and, in the process, dope the organic film. We demonstrate an enhancement of 1–2 orders of magnitude in current. This change is clearly distinguishable from the previous observed difference between transport through high quality and defective monolayers. A detailed analysis of the electrical transport at different temperatures shows that the dopants modify the transport mechanism from tunnelling to hopping. This study suggests a way to extend significantly the use of monolayers in molecular electronics.     

Standpunkte, Praktiken und Kenntnisstand zur Ferkelkastration in Europa (PIGCAS) – Projektziele und erste Ergebnisse

Most of the male piglets in the EU are castrated. According to the current EU legislation, surgical castration can be performed without anaesthesia up to the age of 7 days. A report of the European Food Safety Authority (EFSA) on the welfare aspects in relation to the castration of pigs has underlined the need for further research. As a follow up, the EU has launched a two-year project (Specific Support Action PIGCAS) within the 6^th EU Framework Programme, starting in January 2007. “PIGCAS” is the acronym for “Attitudes, practices and state of the art regarding piglet castration in Europe”. The main objectives are: [A] to collect information on the attitudes of the various stakeholders (consumer groups, NGOs and industry stakeholders); [B] to collect information on the extent of the practice of castration of piglets (male or female) within the EU and the conditions under which castration is performed; [C] to evaluate research work and other sources of information, in order to examine surgical castration without anaesthesia and its possible alternatives from different perspectives and derive research priorities; and [D] to integrate the collected information and evaluation in a report providing support for EU policy in the field of research and legislation. Preliminary results are now available on objectives [A] and [B]. When referring to the alternatives to surgical castration, one has to distinguish between short-term and long-term solutions. Surgical castration with anaesthesia was mentioned by most of the stakeholders as a short-term alternative. Genetic control of boar taint and sperm sexing to select only females for pork production are considered as long-term alternatives. Current practices of castration and levels of acceptability vary substantially between and within countries and regions. The current research focuses on practical methods for acute and postoperative pain alleviation and analyses the complex consequences of raising entire males or immunocastrated boars. Considering the different dimensions (attitudes, extent of practice, animal welfare, pork quality and economy) of importance, it is intended to propose to the EU short and long-term strategies to handle this problem.

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Eingegangen: 26. Februar 2008; angenommen: 29. Februar 2008     

Deliqueszenz und Effloreszenz hygroskopischer Salzpartikeln in Partikel‐Wand‐ und Partikel‐Partikel‐Kontakten

In case of dust separation with surface filters, adhesive bonds at particle‐wall and particle‐particle contacts are of great importance. The deliquescence and efflorescence of hygroscopic salt particles can significantly influence the adhesive bonds at particle contacts with such salt particles. Therefore, to investigate these phenomena, various types of particle contacts were produced by the separation of aerosols on filtering collectors and subsequently observed in the chamber of an environmental SEM during the moisture‐induced deliquescence and efflorescence.