Lernprozesse zum Thema Schatten und Lichtausbreitung

Die Arbeit ist eingebettet in ein Forschungsprojekt, das die Unterrichtsmethode Cross-Age-Peer-Tutoring (CAPT) untersucht und analysiert, ob die Strategie zum Aufbau konzeptuellen physikalischen Verständnisses führt. Unterstützt von Wissenschaftern/innen der Universität Wien untersuchen Schüler/innen in der Rolle von Forscher/innen die Vorstellung jeweils jüngerer Schüler/innen und adaptieren dabei ihre eigenen Vorstellungen. Der Fokus der vorliegenden Studie liegt auf der Untersuchung der Lernprozesse der Schüler/innen. Inhaltlich werden Schülervorstellungen in der Optik adressiert, im Besonderen die Themenbereiche Lichtausbreitung und Schatten. Es werden zwei Fragestellungen genauer betrachtet. Erstens wird nach dem Einfluss des Engagements der Tutoren/innen auf die Lernprozesse der Tutees gefragt. Zweitens wird analysiert, ob sich auch bei den Tutoren/innen im Verlauf ihrer Tutoring-Aktivität Lernprozesse identifizieren lassen. Die auf den Forschungsfragen basierenden Hypothesen konnten mit Hilfe von Mixed-Methods-Research bestätigt werden. Abgesehen davon, dass ich meine forschungsmethodologischen Kenntnisse im Laufe des Entstehens der Arbeit ganz bedeutend erweitern konnte, wurde für mich klar, dass die Auseinandersetzung mit den wichtigsten neuen Erkenntnissen der fachdidaktischen Forschung auch für meine zukünftige Berufspraxis empfehlenswert ist.This work is part the of a science project which examines the Cross-Age-Peer-Tutoring method in order to find out whether this strategy leads to establishing a physical conceptual understanding. Supported by scientists of the University of Vienna, students in the role of scientists examine the perception of younger students and thus adapt to these student´s perceptions. This study is focused on the examination of student learning processes. Contentswise the student’s perceptions are addressed optically, with special attention to the topics of light propagation and shadow. Two different considerations are analyzed: Firstly the influence of the tutor’s engagement on the tutees learning process is questioned. Secondly it is analyzed whether the tutors themselves go through a learning process during their tutoring activity. The hypothesis based on these scientifical questions was confirmed with the support of Mixed-Method-Research. Besides the fact that I could extend my knowledge in research methodology during the process of my work, it also became clear to me that the involvement with the most important new findings in the field of teaching methodology research is important for my future practical experiences

The effect of variable accretion on the vertical structure of protostellar disks

Diese Arbeit befasst sich mit dem Einfluss von FU Orionis ähnlichen Helligkeitsausbrüchen auf die vertikale Struktur einer protostellaren Scheibe. FU Orionis Sterne sind junge Objekte, die einen abrupten Anstieg in ihrer Helligkeit von einigen Größenklassen zeigen. Dieses Phänomen kann durch hohe Massenakkretionsraten in der Frühphase der Sternentstehung erklärt werden. Die wesentlichen Scheibenparameter während eines FU Orionis ähnlichen Helligkeitsausbruches werden durch die zwei-dimensionalen, hydrodynamischen Simulation von Vorobyov & Basu (2006, 2010a) berechnet. Dieser Simulation liegt die Annahme einer dünnen Scheibe zu Grunde. Unter der Annahme eines vertikalen thermischen und hydrostatischen Gleichgewichts werden die Gleichungen für den Strahlungstransport gelöst und die vertikale Struktur der Scheibe rekonstruiert. Die Ergebnisse zeigen, dass die vertikale Struktur der Scheibe während eines Helligeitsausbruches mehr ausgedehnt ist und die Dichten nahe der Mittelebene stark abnimmt. Es wird gezeigt, dass die Annahme einer dünnen Scheibe trotz dieser Ausdehnung gerechtfertigt ist. Die vertikale Dichteverteilung der Scheibe wird basierend auf der Henvey-Methode rekonstruiert, die eine um den Faktor 10 bessere Konvergenz zeigt als der ”Shooting- Bisection” Algorithmus.This thesis considers the impact of FUori-like luminosity bursts on the disk vertical structure. In the early stages of star formation the accretion rate onto the star is a highly variable process, where intense bursts of accretion can occur. These high accretion rates lead to a sharp increase in luminosity by several orders of magnitude as observed in FU Orionis stars. Based on the twodimensional, thin-disk, hydrodynamical simulation of Vorobyov & Basu (2006, 2010a), I reconstruct the disk vertical structure at such a luminosity burst and during the subsequent quiescent phase, using coupled equations of local hydrostatic equilibrium and vertical radiation transfer. The results show that the temperature of the disk is significantly increased during the burst, leading to an extended vertical disk structure and lower gas volume densities near the midplane. The requirement of the thin-disk approximation is fulfilled during the burst up to several hundred AU. I find that the disk scale height is significantly reduced at the positions of fragments due to self-gravity, which helps to shield fragments from stellar irradiation. This may increase the likelihood of survival of fragments. Different methods for the reconstruction of the vertical disk structure are tested and the algorithm based on the Henvey method has shown an order of magnitude faster convergence than the shooting and bisection algorithm

A domestic solar/heat pump heating system incorporating latent and stratified thermal storage.

Both solar and heat pump heating systems are innovative technologies for sustaining ecological heat generation. They are gaining more and more importance due to the accelerating pace of climate change and the rising cost of limited fossil resources. Against this background, a heating system combining solar thermal collectors, heat pump, stratified thermal storage and water/ice latent heat storage has been investigated. In order to investigate and optimise the heating system, a dynamic system simulation model was developed. On this basis, a fundamental control strategy was derived for the overall co-ordination of the heating system with particular regard to the performance of the two storage tanks. In a simulation study, a fundamental investigation of the heating system configuration was carried out and optimisation derived for the system control as well as the selection of components and their dimensioning. The influence of different parameters on the system performance was identified, where the collector area and the latent heat storage volume were found to be the predominant parameters for system dimensioning. For a modern one-family house, a solar collector area of 30m² and a latent heat store volume of 12.5m³ are proposed. In this configuration, the heating system reaches a seasonal performance factor of 4.6, meaning that 78% of the building’s and users’ heat demand are delivered by solar energy. The results show that the solar / heat pump heating system can give an acceptable performance using up-to-date components in a state-ofthe- art building. A novel but most significant component of the heating system is the latent heat store, working with water / ice as phase change material. For that reason, the store was developed in a systematic manner with special regard to the heat exchangers. Based on a detailed specification and a functional analysis, concept solutions were investigated and evaluated. A sheet matrix heat exchanger was eventually chosen as it fulfils the specialised requirements of the heating system. The heat exchanger’s behaviour and its performance during phase change were analysed in laboratory tests. In addition, a storage tank design was developed and a preliminary storage dimensioning carried out for the heating system as defined by the simulations, showing that five polymer tanks with 3.3m³ each and 14 sheet matrix heat exchangers in each tank are required

Investigating the Performance of Rural Off-Grid Photovoltaic System with Electric-Mobility Solutions: A Case Study Based on Kenya

Over the last years, stand-alone and / or hybrid photovoltaic systems have spread in rural areas, especially in Sub-Saharan Africa. Compared to conventional systems (typically diesel generators), these systems can provide a reliable electricity supply at reasonable costs with a low degree of greenhouse gas emissions. Therefore, this paper focuses on modelling and investigation of an off-grid photovoltaic system (charging station) performance based on a located in Kenya. However, the model can be adapted to any other region and any type of photovoltaic systems module by changing model input data such as solar radiation, air temperature, longitude, latitude, load profile and standard test conditions parameters of the photovoltaic systems module. The modelled photovoltaic system (charging station) will be used to provide reliable and clean electricity for a number of important tasks (e.g. water purification, charging special floatable lanterns and electric bikes)

Cross-Modal Search and Exploration of Greek Painted Pottery

This paper focuses on digitally-supported research methods for an important group of cultural heritage objects, the Greek pottery, especially with figured decoration. The design, development and application of new digital methods for searching, comparing, and visually exploring these vases needs an interdisciplinary approach to effectively analyse the various features of the vases, like shape, decoration, and manufacturing techniques, and relationships between the vases. We motivate the need and opportunities by a multimodal representation of the objects, including 3D shape, material, and painting. We then illustrate a range of innovative methods for these representations, including quantified surface and capacity comparison, material analysis, image flattening from 3D objects, retrieval and comparison of shapes and paintings, and multidimensional data visualization. We also discuss challenges and future work in this area.Comment: 14 pages, 10 figures, preprint for a book chapter, supplementary video available at https://youtu.be/x_Xg0vy3nJ

Antiferromagnetism and Superconductivity in UPt_3

The short ranged antiferromagnetism recently seen in UPt_3 is proved incompatible with two dimensional (2D) order parameter models that take the antiferromagnetism as a symmetry breaking field. To adjust to the local moment direction, the order parameter twists over very long length scales as per the Imry-Ma argument. A variational solution to the Ginzburg-Landau equations is used to study the nature of the short ranged order. Although there are still two transitions, the lower one is of first order -- in contradiction to experiments. It is shown that the latent heat predicted by the 2D models at the lower transition is too large not to have been seen. A simple periodic model is numerically studied to show that the lower transition can not be a crossover either.Comment: To appear in Journal of Physics: Condensed Matter. 9 pages, 2 figure

Face to face - close range inspection of head vases

Several hundred attic head vases are known worldwide and stored in museums and collections. In 1929, Beazley has categorized twenty groups (A-W) based on stylistic properties and historic methodology. Head vases are assembled in several steps, most important for our comparison is the moulding of the head area. While the other parts of head vases like the size of the handle and the painting can differ significantly from each other, one can notice similarities in the head shapes of the same group. Since molds were used to shape the heads, our initial hypothesis was to perform a quantitative comparison of head shapes based on digital scan data. Comparison of scan data is straight forward and is very similar to quality control and inspection processes in industrial applications. Nonetheless, quality control of approximately 2,500-year-old artefacts that are distributed among several different places is not straight forward. Initial analysis was performed on older scan data. In addition, a high-resolution fringe projection scanner was employed to scan further head vases in additional museums in Germany and Italy. Scan resolution and accuracy of approximately 0.1 mm in all dimensions were required to reveal differences below 1 mm. All new scans were performed with an AICON SmartScan-HE C8. This scanner captures not only shape, but at the same time records color textures which can be employed for presentation or future analyses. Shape analysis results of the head areas do not only confirm that it is likely that the same mold was used for shaping some of the head vases. According to these results, it is also not unlikely that a first generation of larger head vases was used to prepare molds for consecutive generations of head vases that are slightly smaller by 10-15%. This volume loss resembles closely the volume loss observed after oven-burning of pottery. Scanning will continue to increase the data set for further analyses

Impact of Locally Available Thermal Insulation Structures on Space Heating Demand of High-altitude Rural Buildings: A Case Study of Kyrgyzstan

Kyrgyzstan is a high-altitude mountainous country situated in a cold climatic zone. The age of the residential buildings, poor housing conditions and the absence of proper thermal insulation result in high heat demand and low thermal comfort in Kyrgyz houses. To maintain thermal comfort, the rural residents use traditional heating stoves to burn solid fuels during the winter months. Overconsumption of natural resources is mainly responsible for deforestation, as well as indoor and outdoor air pollution. Implementation of building thermal insulation is considered as one of the potential measures for energy conservation. In regards to this, the presented research proposes the various thermal insulation structures developed from the locally available natural materials. Further to this, it identifies the effectiveness of various thermal insulation structures on the annual space heating demand of a highaltitude single-family house located in rural Kyrgyzstan. The results show that the insulation parameter helps to save a considerable amount of space heating demand by up to 30 % in the case of existing houses and up to 70 % for newly built houses in rural Kyrgyzstan

The Energy Situation in Central Asia: A Comprehensive Energy Review Focusing on Rural Areas

The research work was funded by the Federal Ministry of Education and Research (BMBF) of the Federal Republic of Germany within the CLIENT II funding programme International Partnerships for Sustainable Innovations under the project “ÖkoFlussPlan” (Project ID 01LZ1802A-F). open access articleThe northern part of the globe is dominated by industrialisation and is well-developed. For many years, the southern part of the world (South Asia, Africa etc.) has been a target of research concentrating on access to energy (mainly electricity) in rural regions. However, the Central Asian region has not been a focus of energy research compared to South East Asia and Africa. Despite plentiful domestically available energy resources, the energy supply in Central Asia is very unevenly distributed between urban and rural areas. Almost half of the total population of Central Asia lives in rural areas and there is a lack of access to modern energy services to meet primary needs. To analyse the energy situation (i.e., electricity, heating, hot water consumption, cooking, etc.) in rural Central Asia, this paper reviews residential energy consumption trends in rural Central Asian regions as compared to urban areas. Furthermore, the paper illustrates the potential of renewable energies in Central Asia. To perform the study, a qualitative comparative analysis was conducted based on a literature review, data, and statistical information. In summary, the presented article discusses the rural energy situation analytically and provides in-depth insights of Central Asian energy infrastructure