HSSS - Hochschulschriftenserver der SLUB

    On the Effect of Thin Film Growth Mechanisms on the Specular Reflectance of Aluminium Thin Films Deposited via Filtered Cathodic Vacuum Arc

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    The optimisation of the specular reflectance of solar collectors is a key parameter to increase the global yield of concentrated solar power (CSP) plants. In this work, the influence of filtered cathodic vacuum arc deposition parameters, particularly working pressure and deposition time, on the specular and diffuse reflectance of aluminium thin films, was studied. Changes in specular reflectance, measured by ultraviolet–visible and near-infrared spectroscopy (UV-vis-NIR) spectrophotometry, were directly correlated with thin film elemental concentration depth profiles, obtained by Rutherford backscattering spectrometry (RBS), and surface and cross-sectional morphologies as measured by scanning electron microscopy (SEM) and profilometry. Finally, atomic force microscopy (AFM) provided information on the roughness and growth mechanism of the films. The two contributions to the total reflectance of the films, namely diffuse and specular reflectance, were found to be deeply influenced by deposition conditions. It was proven that working pressure and deposition time directly determine the predominant factor. Specular reflectance varied from 12 to 99.8% of the total reflectance for films grown at the same working pressure of 0.1 Pa and with different deposition times. This transformation could not be attributed to an oxidation of the films as stated by RBS, but was correlated with a progressive modification of the roughness, surface, and bulk morphology of the samples over the deposition time. Hence, the evolution in the final optical properties of the films is driven by different growth mechanisms and the resulting microstructures. In addition to the originally addressed CSP applications the potential of the developed aluminium films for other application rather than CSP, such as, for example, reference material for spectroscopic diffuse reflectance measurements, is also discussed

    Zachary Macaulay and the Development of the Sierra Leone Company, 1793-4 - Part 1, Journal, June-October 1793

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    This volume is the first instalment of the Sierra Leone journals and diary of Zachary Macaulay (1768-1838), who arrived in Sierra Leone in December 1792 as one of two members of council appointed to assist the governor of the Sierra Leone Company's new colony for free blacks

    Vorfahrt für Kinderrechte

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    Die Rechte von Kindern und Jugendlichen stellt niemand in Abrede. Dennoch hat Sachsen bisher die UN-Kinderrechtskonvention nicht in vollem Umfang umgesetzt. Kinder und Jugendliche werden in aller Regel nicht als Experten in eigener Sache wahrgenommen: sei es bei der Planung eines neuen Spielplatzes oder eines Fußgängerüberweges im eigenen Stadtteil. Kinder und Jugendliche haben ein Recht auf Partizipation und Beteiligung an allen Entscheidungen, die ihr Leben unmittelbar berühren. Die eigenen Interessen wahrzunehmen, zu äußern und sich mit anderen auseinanderzusetzen kann gelernt werden

    Behind the data – preservation of the knowledge in CH Visualisations

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    The basics of visualisations in the context of Cultural Heritage are not broadly defined. But this is the precondition to find out suitable and practical strategies to document and manage the knowledge contained therein. For this, the paper focusses the properties, potentials and typologies of Cultural Heritage visualisations related to application fields and possibilities as well as documentation strategies, creation process and methodology. The paper starts with a theoretical overview of the properties and potential of visualisation related to the usability in the context of Cultural Heritage. On this basis the correlation between application possibilities and the three application fields - research, transfer of knowledge and preservation - will be discussed. In a second part, the paper identifies the similarities and differences of typical working processes and methodologies by the study “Investigation of 3D modelling workflows in CH with the object of development of key concepts and definitions”. This is a subproject of the project COSCH with the purpose to create a framework called COSCHKR as an international and interdisciplinary platform for state-of-the-art documentation of Cultural Heritage. For this, the main topic of the study was the analysis, evaluation and comparison of thirty different 3D projects of three institutes. It was possible to define different types of CH visualization and framework of a working process. Third topic is the documentation and management of knowledge of such visualisation in the field of Cultural Heritage. The paper compares three current research projects and points out commons and differences of the different strategies. At the end, a synthesis gives a first idea for common strategies and best practice guidelines of Cultural Heritage visualisation related to the process, methodology and documentation. Purpose – Find out general strategies to document and manage knowledge Design/methodology/approach – Based on investigation and evaluation of different projects. Originality/value – Most of the projects are a special application for one research question, this methodology raises a common claim. Practical implications – The outcomes of the investigation is a basis for further practical applications with a high range of usability

    Steigender Strompreis und kein Ende?

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    Viele Energieunternehmen begründen Preiserhöhungen mit der Förderung von Wind-, Biomasse- und Sonnenstrom durch das Erneuerbare-Energien-Gesetz (EEG) nach dem Motto: „Weil so viele Windräder und Solaranlagen gebaut werden, steigt der Strompreis!“ Mit dem erfolgreichen Ausbau der erneuerbaren Energien hat die Preisentwicklung der letzten 15 Jahre aber fast nichts zu tun. Verschwiegen wird zudem der ökonomische Nutzen erneuerbarer Energien. Diese haben im Gegensatz zu Kohle und Atomkraft ehrliche Preise, denn es entstehen keine Folgekosten, die nicht im Preis enthalten sind. Atommüll, Klima- und Umweltschäden müssen dagegen von der Allgemeinheit bezahlt werden

    Warum brauchen wir ein neues Vergabegesetz in Sachsen?

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    Die GRÜNE-Landtagsfraktion hat einen Gesetzentwurf vorgelegt, in dem das Sächsische Vergabegesetz an die modernen europäischen Richtlinien angepasst und ökologische sowie soziale Kriterien bei Vergaben und Beschaffungen der öffentlichen Hand in Sachsen berücksichtigt werden. Außerdem werden Regelungen zur Tariftreue, Mindestlohn, Lospflicht, bürokratiearmen und qualitätssichernden Vergabe und zu internationalen Arbeitsnormen im Gesetz verankert

    Graphing Meeting Records - An Approach to Visualize Information in a Multi Meeting Context

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    Purpose – Meeting notes are effective records for participants and a source of information for members who were unable to attend. They act as a reference point to decisions made, to plan next steps, and to identify and track action items. Despite the need for a multi meeting solution (Tucker and Whittaker, 05), meetings are often displayed as separated as well as descriptive documents. The aim of this work is to enhance access to overlapping meeting contents and existing coherences beyond a decoupled description. A visual representation of meeting content can lead to meeting records which are more comprehensible and more time efficient. Furthermore, it enables the depiction of knowledge that is often lost in conventional meeting records. Approach – Our goal was to define a general structure for meeting items, integrating content categories and relations between successive meetings. In this paper, we present a model based approach to visualize meeting content as well as content relations in order to support the preparation, execution and follow-up of meetings. Due to the fact that contents of consecutive meetings refer to each other (Post et al., 04), we consider meetings as a series of events. The resulting model substantiates the transformation of content as well as content relations into a visual form. Value – The proposed solution focuses on the model that is integrated into an interactive visualization. Thus, a novel approach to explore meeting records is provided. The model was proved to be suitable for meeting contents in various use cases. Examining the content in its visual representation across multiple consecutive meetings enhances the identification of any linked information at a glance over even long periods of time. Hence, important pieces of information will not be disregarded. Practical implications – The approach of our multi meeting protocol application is realized as a browser-based implementation that displays data from JSON objects. With this interactive visualization, the user can browse, search, and filter meeting content and get a deeper understanding of topics, their life cycle and relations to other topics. This leads to an overall comprehension of project or business progression that highlights topics that need to be addressed. Thus, the viewer is supported in preparing, executing, and following up meetings successfully and qualified to structure records in order to keep a clean transcript of a meeting

    Forest fire dynamics and carbon stocks in different ecological zones of Ghana

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    Fires occur in most forest reserves in Ghana. However, there is a limited understanding of the fires and their behaviour in the different ecological zones. Therefore, this research was to analyze the spatial and temporal distribution of fires, examine the driving factors, direct and underlying causes and impacts of the fires, determine and compare the fuel dynamics to predict fire behaviour and estimate the effects of fire on carbon stocks in different ecological zones of Ghana. The research used different methodologies including questionnaires, fire records, satellite fire data from MODIS (2001 to 2015) (first approach) and field experiment (second approach). A total of 304 respondents was sampled for eight communities, two communities each around the moist and dry semi-deciduous forest, upland evergreen forest and savanna. The spatial distribution of fire showed a trend along the forest boundaries, open vegetation, degraded areas, human settlements, shrubs, farms, rivers and roads. The temporal trend was significant in the dry forest (435 hotspots), followed by the savanna (229 hotspots), moist forest (76 hotspots) and the least in the evergreen forest (5 hotspots). The fires were observed from August, October to May with the dry forest having the longest seasonality. Sunday, Tuesday and Thursday were the peak days of the detected fire hotspots in the dry, moist and savanna respectively. Most of the fires in the different ecological zones peaked from 13 to 14 pm. The results of the research also revealed that the fires were driven primarily by socioeconomic factors which were supported by environmental, type of vegetation and cultural factors. In all the ecological zones, fires were originating from humans. The study pointed out three categories of human-caused fires through activity (farming), non-activity (carelessness or negligence) and others (unknown causes). The major underlying causes of fire mentioned were the inadequate management of the forest and weak compliance and enforcement of forest laws. All these fires have resulted in several impacts in the various ecological zones. Concerning the fuel dynamics, the total downed woody fuel load in the evergreen forest was found to be higher (228 and 208.4 tonnes per hectare). The litter and duff density (112.2 kilogram per cubic meter) in unburned area and loading (6.3 and 13.5 tonnes per hectare) for both burned and unburned area respectively were significantly greater in the moist forest. Also, the dry forest showed 2.4 tonnes per hectare of herbaceous loading in the burned area. However, fires were predicted to be severe in the savanna regarding the surface rate of spread, flame length and fireline intensity, but with low reaction intensity and heat per unit area. The total amount of aboveground tree carbon, aboveground non-tree and belowground root for both burned and the unburned area varied under the different ecological zones. The highest was seen in the moist forest with the emission of 294 tonnes of carbon per hectare accounting for 82% losses. This research has brought out the current situation of fire in the various ecological zones for the implementation of necessary actions for the future
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