"Zugleich diese gute Statt [...] ihre Seel und Leben gleichsamb auß dem Weser=trafiquen habend": die Weser als Gegenstand literarisch-rhetorischer Bemühungen (1550 - 1685 - 1760 - 1796)

From ancient times to the present, rivers have been a popular literary theme and motif. The river can be understood as an image of unceasing movement, as a connective or divisive element, as a source of fertility and prosperity through trade, but also as one of danger. The Weser is one of the many rivers of Germany to have been commemorated in literature, as is illustrated here with the aid of examples from the sixteenth to the eighteenth centuries. The German humanist Felix Fi(e)dler’s 1550 cycle on the rivers of his native country forms the point of departure for this discussion. With his poetic description of the Weser, Fi(e)dler left a striking monument to posterity which reflects his knowledge of the literature of antiquity. It was from this age-old literature that he drew his information about the disputes between the Romans and the Teutons thought to have taken place on and near the Weser. Here the river is ascribed a Germanic, "national" element which would also play a role in its later depictions. In the academic speech of 1685 by Nicolaus Mindemann of Bremen, this use of antique literature as an orientation and the emphasis on the historical significance of the Weser as a "German river" recede into the background in favour of a focus on geographical-topographic and economic aspects. For Mindemann, the Weser is the source of trade carried out in Bremen, and hence of the city’s well-being. Here the processing of the river as a literary theme is combined with a eulogy of the city of Bremen in a form reminiscent of a "Städtelob" (speech or song in praise of a city). In his poem Die Weser of 1760, on the other hand, Michael Conrad Curtius directed his attention once again to the “national” element, prompted by the events of his day. Finally, at the end of the eighteenth century, this element underwent negative reinterpretation in Schiller’s Weser epigram from the Xenia. Here the Germanic-national aspect stands for darkness and lack of civilization in contrast to the brightness of antiquity. In Schiller’s work, the Weser’s character as a "German river" - frequently referred to in literature even of the nineteenth and twentieth centuries - and as the symbol of a national myth is satirically contradicted

High-temperature strain sensing using sapphire fibers with inscribed first-order Bragg gratings

Strain sensor designs and strain measurements based on single-crystal sapphire fibers with inscribed first-order fiber Bragg gratings for applications up to 600 °C are presented. We report on all the details of two different sensor designs; for instance, we show that the resolution of multimode sapphire fiber Bragg grating (SFBG) strain sensors is about l / l = ¼ 10-5 (10 µstrain), which is comparable with state-of-the-art high-temperature sensors. We apply our sensors for the determination of the thermal expansion coefficients of high-temperature steel alloys, showing a good match to known values. Hence, we believe that SFBG sensors may represent a promising alternative to currently used non-optic-based strain-detecting devices

Faser-Bragg-Gitter für die Hochtemperaturanwendung

Im Rahmen der Dissertation wurden die Eigenschaften von Faser-Bragg-Gittern (FBG) in zwei speziellen Fasern unter dem Gesichtspunkt der Hochtemperaturstabilität (>800°C) untersucht. Die Gitter wurden dabei unter Verwendung eines frequenzverdoppelten Ti:Sa-basierten Femtosekundenlasers in einem Zweistrahl-Phasenmasken-Interferometer zum einen in einer einkristallinen Saphirfaser und zum anderen in einer Alumosilikatglaskernfaser erzeugt. Für die Gitter in der Saphirfaser, konnte experimental Temperaturstabilität bis ca. 1900°C nachgewiesen werden. Die zweite Faser wurde zunächst erst einmal nach einem neuartigen Ansatz aus einem mit Quarzglas umfangenen Saphirstab verzogen. Die so entstandene Alumosilikat-glaskernfaser (AluSi-Faser mit ca. 50 mol-% Al2O3-Anteil im Faserzentrum) zeigt eine Temperaturstabilität der eingeschrieben FBG von bis zu 900°C. Beide Fasern wurden hinsichtlich ihrer Führungseigenschaften Untersucht und auf diesen Ergebnissen basierend die Reflexionseigenschaften der in ihnen erzeugten Faser-Bragg-Gitter modelliert. Auch wenn beide Fasern extrem mehrmodig sind, führen die verscheiden Brechzahlprofile (Stufenindexprofil der Saphirfaser, parabolisches Gradientenindexprofil der AluSi-Faser) zu grundlegend verschiedenen FBG-Charakteristika. Für beide Fasern wurden entsprechend angepasste Auswertealgorithmen genutzt um die temperaturabhängige Braggwellenlängen-verschiebung der FBG aus dem breitbandigen Reflexionssignal (Saphirfaser) und dem äquidistanten Mehrpeakspektrum (AluSi-Faser) zu erhalten. Derart konnten mit beiden Fasertypen Einzelmess- und Wiederholgenauigkeiten von wenigen Kelvin für die FBG-basierten Temperaturmessungen erreicht werden

Two-Step-Model of Photosensitivity in Cerium-doped Fibers

The photosensitivity of various cerium-doped fibers has been experimentally investigated for both excimer- and femtosecond-laser illumination. The results of single-pulse, few-pulse and multi-pulse inscription of fiber-Bragg-gratings with both laser systems and the thermal aging of those gratings demonstrated the restrictions of the conventional color center model for cerium-doped fibers. To explain the short-term stability of single-pulse gratings against long-term stability of multi-pulse gratings, an extension into a two-step-model was deduced

Germania and alumina dopant diffusion and viscous flow effects at preparation of doped optical fibers

We report on germania and alumina dopant profile shift effects at preparation of compact optical fibers using packaging methods (Stack-and-Draw method, Rod-in-Tube (RiT) technique). The sintering of package hollow volume by viscous flow results in a shift of the core-pitch ratio in all-solid microstructured fibers. The ratio is increased by about 5% in the case of a hexagonal package. The shift by diffusion effects of both dopants is simulated for typical slow speed drawing parameters. Thermodynamic approximations of surface dissociation of germania doped silica suggest the need of an adequate undoped silica barrier layer to prevent an undesired bubble formation at fiber drawing. In contrast, alumina doping does not estimate critical dissociation effects with vaporous aluminium oxide components. We report guide values of diffusion length of germania and alumina for the drawing process by kinetic approximation. The germania diffusion involves a small core enlargement, typically in the sub-micrometer scale. Though, the alumina diffusion enlarges it by a few micrometers. A drawn pure alumina preform core rod transforms to an amorphous aluminosilicate core with a molar alumina concentration of only about 50% and a non-gaussian concentration profile

Regional Railway Governance – Akteursnetzwerke im regionalen Bahnsystem im internationalen Vergleich

Objective and subject of investigation: Europe's railway systems have undergone a profound transformation process over the last 20 years. As part of the process of reforming the European rail sector, privatisation, liberalisation and regionalisation processes were initiated and implemented with varying national radicalism. In Germany and Great Britain, the reformation of railway systems began at the same time in the early 1990s. However, the following development has followed different development paths in both countries. The differing implementation models of the reform have therefore strongly influenced the structure and functioning of the railway systems concerned. As a result of the regionalisation process, stakeholder networks in regional railway systems have either been restructured or even been organized and established for the first time. Those stakeholder networks are the focus of interest in this paper.Against this background, this paper researches governance in the regional rail system. As a specific form of governance, the network-based collaboration between the stakeholders is examined. Building on the approaches of network research and the governance concept, this paper analyses the composition and functioning of stakeholder networks in the regional railway system. Differing network structures is a result of different development paths pursued in the respective national context. A particular focus is laid on the participatory approach towards an involvement of civil stakeholders and the importance of participatory approaches for the stakeholder network in the regional railway system. Research methods: The comparison of two case studies forms the research approach for this paper. Due to the simultaneous reform of the rail sector, but completely different implementation models and resulting different structures, case studies from Germany and Great Britain are suitable for comparing present stakeholder networks and their functioning. The German region of Aachen as well as the British region of Lancashire were selected for this comparative study of governance in the regional rail system. Considering the different paths of development pursued following the reform of the respective national rail systems, this paper compares the present structures and way of functioning of stakeholder networks in the regional rail systems. The aim is to identify differing overall conditions and influencing factors and to present the resulting organisational structures and decision-making processes. In addition, the comparative study makes it possible to identify similarities and differences that characterise the regional railway system. It also examines the extent to which the identified structures allow or aggravate more intensive participation by civil stakeholders. The study of stakeholder networks builds on the relational perspective of network research, which examines existing relationships between stakeholders and illuminates their accomplishment. The governance concept provides the theoretical framework by considering forms and mechanisms of coordination between more or less autonomous stakeholders whose actions are interdependent. Building on approaches from social network research and the governance concept, different research methods are applied. More precisely document analysis, participatory observations as well as qualitative expert interviews were conducted. Findings: The findings demonstrate that stakeholder networks exist in the regional rail systems of the two case studies, but these are no official or formalised associations of different stakeholders. In fact, stakeholders with competences or interest in the regional railway system work together in a network because of their interdependency. According to the results of the expert interviews, these network structures can be described as not formalized, but institutionalized. Public transport by rail is no longer organised by public stakeholders exclusively. As a result of privatisation, liberalisation and regionalisation, the present stakeholder network is composed heterogeneously and comprises public, private and civil stakeholders. On the one hand, stakeholders with different motivations collaborate cooperatively, on the other hand the organisation of the functional railway system has gained complexity. Decision-making processes are negotiated in the network between all stakeholders concerned. However, the research results in this thesis show that some stakeholders are able to influence the process much more than others. The commissioning authorities in the German case study and the Department for Transport (DfT) in the British context hold a powerful position for instance. One of the reasons for this can be found in the financing of local transport services, which is secured by the above-mentioned stakeholders. With regard to the participatory involvement of civil stakeholders, the comparison between the German and British case studies reveals clear differences. In Germany, civil stakeholders appear primarily as institutionalised associations or interest groups. Accordingly, the stakeholder network is primarily designed for the integration of such professionalised civil stakeholders, although interviewed experts state that this could undoubtedly still be improved. With regard to participatory structures the British case study, on the other hand, presents "Community Rail Partnerships" as a successful model, which function as an integrator and hereby enable a permanent involvement of different players. As a result, the regional railway system benefits from a supporting participatory culture, which is reflected in constructive collaboration between public, private and civil stakeholders. The advantages and potentials resulting from this participatory governance are discussed in detail as well as possibilities for the transfer of best practice approaches to other regions

Die Inkunabeln der Staats- und Universitätsbibliothek Bremen: ein Zensus

(gedruckte Version mit Abbildungen in: Bremisches Jahrbuch 84, 2005, 202-232)202232Bremen8