Increasing the efficiency of heat transfer in a complex evaporator structure

Magistrsko delo obravnava prenos toplote v kompleksni strukturi cevno-ploščnega uparjalnika, ki se uporablja v gospodinjskih hladilnikih. V prvem delu je predstavljen analitični model za popis porazdelitve temperatur, toplotnih tokov in toplotnih upornosti v strukturi uparjalnika. Analitični rezultati so primerjani z numerično simulacijo. V drugem delu so predstavljene ideje in rezultati iskanja novih konstrukcijskih rešitev za povečanje učinkovitosti prenosa toplote. Ideje so vrednotene glede na njihov vpliv na toplotni tok, tehnično izvedljivost in stroškovno upravičenost.The topic of this thesis is heat transfer in the complex structure of a hot-wall evaporator, used in household refrigerators. An analytical model for describing temperature, heat flow and thermal resistance distribution in a hot wall evaporator structure, of a household refrigerator, is presented in the first part of this thesis. Analytical results are compared with a numerical simulation. Ideas and results of possible design improvements, for increased heat transfer in the evaporator structure, are presented in the second part of this thesis. They are evaluated by their influence on heat flow increase, technical feasibility and costs

Idealizations of the Kleinhaus: On the Typology of the Small Single-Family House in Germany, 1920s–1960s

In the 20th century, detached single-family houses proliferated in Germany. Continued publication of built houses as idealised, model homes in magazines for non-professional housebuilders contributed to the popularity of detached single-family housing, influenced the architecture of single-family homes, and contributed to shaping the culture of habitation. Through their customer magazines, aimed at non-professional housebuilders, German building societies played a crucial role in the constitution of self-provided detached housing. With a focus on the Kleinhaus (small house), this paper uses mediated representations of built houses to trace the evolution of single-family houses in Germany from the 1920s to the 1960s, as they were represented in Mein Eigenheim, a customer magazine of the Wüstenrot — Gesellschaft der Freunde (GdF) building society. During the Weimar era (1919–1933), the GdF magazine highlighted the affordability and modest size of the Kleinhaus. Following the financial crisis of the late 1920s and the rise of Nazism, the economy of self-sufficiency, centred on vegetable gardens, became a popular theme. During the 1950s, under the influence of increasing material progress, the significance of the Kleinhaus changed. The gardens lost their economic function and became extended living spaces. In the late 1950s, the Kleinhaus lost its dominant position on the housing market, with the emergence of new building types such as the bungalow and larger homes with two full storeys, which better catered to the desires of an affluent and increasingly individualised society

The Practice of Self-provision in Suburban Detached Homes

Do practices of self-provision such as the self-organized adaptation of homes, neighbourly help and the contracting of tradespeople, etc. contribute to the re-constitution of local communities in suburban areas? Do self-organized renovations extend the service life of existing building stock as a crucial non-renewable cultural resource? This study is based on empirical on-site research. The sample comprises 26 recently acquired second-hand detached homes. Research has shown that most owner-occupiers rely on self-provision and self-build to renovate used properties. A better supply of affordable, existing homes in suburban areas could help consolidate the development of towns. Hence, redevelopment strategies for suburban residential areas should integrate the potential of self-provision.

Imaging ultra thin layers with helium ion microscopy: Utilizing the channeling contrast mechanism

Background: Helium ion microscopy is a new high-performance alternative to classical scanning electron microscopy. It provides superior resolution and high surface sensitivity by using secondary electrons.\ud \ud Results: We report on a new contrast mechanism that extends the high surface sensitivity that is usually achieved in secondary electron images, to backscattered helium images. We demonstrate how thin organic and inorganic layers as well as self-assembled monolayers can be visualized on heavier element substrates by changes in the backscatter yield. Thin layers of light elements on heavy substrates should have a negligible direct influence on backscatter yields. However, using simple geometric calculations of the opaque crystal fraction, the contrast that is observed in the images can be interpreted in terms of changes in the channeling probability.\ud \ud Conclusion: The suppression of ion channeling into crystalline matter by adsorbed thin films provides a new contrast mechanism for HIM. This dechanneling contrast is particularly well suited for the visualization of ultrathin layers of light elements on heavier substrates. Our results also highlight the importance of proper vacuum conditions for channeling-based experimental methods\u

Land-management strategies and the detached housing stock in shrinking municipalities: evidence from Germany

For some years, increased attention has been paid to the single-family housing stock in Germany and the further designation of building land by municipalities. A Germany-wide anonymous survey of municipalities sheds light on the municipalities' land management strategies with regard to declining populations and their anticipation of future problems for the further use of the single-family housing stock. The results of the quantitative survey are supplemented by qualitative interviews with municipal experts from case studies that were selected on the basis of criteria such as population decline, old-age dependency ratio, the share of single-family homes and vacancy rates. The aims of the survey and the interviews are to assess municipal representatives' perceptions of population decline and of the necessity of undertaking measures to deal with shrinkage. Research questions are: What measures do municipalities consider appropriate to counter population loss and falling demand for housing in shrinking regions? How important are single-family housing areas in the perception of German municipalities? The results indicate that a continued designation of building land seems to be one of the most important measures used to cope with insufficient demand. The aim is to attract new inhabitants, particularly to shrinking cities. However, this approach reinforces current problems because it lowers demand for the housing stock and increases the risk of vacancies.Seit einigen Jahren wird der Einfamilienhausbestand in Deutschland und die Praxis weiterer Baulandausweisungen von Kommunen mit erhöhter Aufmerksamkeit betrachtet. Der vorliegende Beitrag gibt Aufschluss über die Landmanagementstrategien von Kommunen vor dem Hintergrund sinkender Bevölkerungszahlen. Die Einschätzung möglicher zukünftiger Probleme für die weitere Nutzung des Einfamilienhausbestandes fußt auf einer anonymen deutschlandweiten Befragung auf der Gemeindeebene. Die Ergebnisse der quantitativen Befragung werden ergänzt durch qualitative Interviews mit Expertinnen/Experten in Fallstudiengemeinden, die nach Kriterien wie Bevölkerungsrückgang, Altenquotient, prozentualer Anteil von Einfamilienhausgebieten und Leerstandsraten ausgewählt wurden. Ziel der Befragung und der Interviews war es zu erfahren, wie die Expertinnen und Experten den Bevölkerungsrückgang einschätzen und ob sie die Notwendigkeit sehen, Maßnahmen gegen Schrumpfung zu ergreifen. Forschungsfragen sind: Welche Maßnahmen halten Kommunen für geeignet, um Bevölkerungsrückgang und rückläufiger Nachfrage bei Einfamilienhäusern entgegenzusteuern? Wie wichtig sind Einfamilienhausgebiete in der Wahrnehmung deutscher Kommunen? Die Ergebnisse deuten darauf hin, dass eine weitere Ausweisung von Bauland eine der wichtigsten Maßnahmen zu sein scheint zur Bewältigung einer unzureichenden Nachfrage, wenn das Ziel ist, neue Einwohnerinnen und Einwohner zu gewinnen, vor allem in schrumpfenden Städten. Dieses Vorgehen verstärkt jedoch die aktuellen Probleme, weil es die Nachfrage nach Bestandsgebäuden senkt und das Leerstandsrisiko erhöht

TECHNOLOGICAL PARAMETERS OF MAINTENANCE OF RAILWAY SUPERSTRUCTURE

Odlike železniškega prometa so predvsem hitrost, varnost in zanesljivost. Te prednosti pa so v največji meri odvisne od stanja železniške infrastrukture. Med glavne naloge upravljanja infrastrukture nedvomno sodi njeno vzdrževanje, h kateremu pa je potrebno pristopiti sistematično, z jasno definiranimi zahtevami in potrebami. Diplomsko delo zajema širok spekter vzdrževalnih aktivnosti, tako v organizacijskem kot v tehničnem smislu. Iskanje novih tehnoloških in tehničnih rešitev v smislu racionalizacije in povečanja učinkovitosti vzdrževanja pa so dandanes glavne naloge upravljavca infrastrukture. Potrebe uporabnikov transportnih storitev bodo v prihodnosti vedno večje, zato je potrebno sistem vzdrževanja, če želi železnica uspešno konkurirati cestnemu prometu, nenehno izboljševati in nadgrajevati.Main distinctions of railway transport are speed, safety and reliability. But these qualities largely depend on the state of railway infrastructure. Maintenance belongs among basic activities of infrastructure management and demands sistematical approach with clearly defined needs and demands. The thesis adresses wide range of maintenance avtivities from both, organisational and technical aspect. Development of new technical and technological solutions in terms of rationalization and effeciency is today infrastructure manager\u27s main challange. Demands of the users will bi much higher in the future and If the railway want to be competitive, especially to the road transport, maintenance system should be constantly improved and upgraded