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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Nano-mélangeurs bolométriques supraconducteurs à électrons chauds en Y-Ba-Cu-O pour récepteur térahertz en mode passif / Superconducting Y-Ba-Cu-O hot electron bolometric nano-mixers for terahertz passive receivers

Ladret, Romain 06 July 2016 (has links)
Nous étudions un mélangeur d'ondes térahertz (THz) réalisé avec le supraconducteur à haute température critique YBaCuO en couches ultraminces (10 à 50 nm). Le travail vise à concevoir un démonstrateur portable pour la détection hétérodyne térahertz passive, avec une cryogénie simplifiée à 60-80 kelvin (projet ANR MASTHER).Le principe de détection est le bolomètre à électrons chauds (HEB) jusqu'à présent développé avec des supraconducteurs à basse température critique. L'effet HEB est mis en ¿uvre dans une constriction en YBaCuO (quelques centaines de nm de dimensions latérales). Cette structure conduit à un détecteur THz sensible et rapide (bande passante instantanée de 100 GHz). Le rayonnement THz est couplé à la constriction par une antenne planaire large bande.En premier lieu, les échanges thermiques entre réservoirs d'électrons et de phonons (YBaCuO et son substrat) sont modélisés. Nous établissons ainsi les conditions optimales pour le HEB en termes de dimensions de la constriction et de puissance de l'oscillateur local requises pour un mélange performant (gain et bruit). Par rapport aux modèles antérieurs, nous introduisons une approche de "point chaud" nouvelle incluant l'influence de la fréquence THz dans YBaCuO, ainsi que l'adaptation d'impédance entre la constriction et l'antenne. En second lieu, nous décrivons l'optimisation des étapes de micro-fabrication des HEB, en particulier les lithographies électronique et optique, pour obtenir des constrictions de 300 nm de côté. De premiers dispositifs ont été testés en détection directe infrarouge. Les performances entre des couches d'YBaCuO ultraminces préparées suivant différentes techniques sont comparées. / We report on the development of a terahertz (THz) wave mixer made from high critical temperature superconducting YBaCuO ultrathin films (10 to 50 nm). The work is part of the MASTHER ANR project aiming at a portable demonstrator for passive terahertz heterodyne detection, implementing simplified cryogenics (60 to 80 kelvin). The detection principle is that of the hot electron bolometer (HEB) so far mainly developed with low critical temperature superconductors. The HEB effect is implemented in an YBaCuO constriction (a few hundred nm in lateral dimensions). This structure can lead to a sensitive and fast THz detector (theoretical instantaneous bandwidth of 100 GHz). The THz radiation is coupled to the YBaCuO constriction by means of a wideband planar antenna. The new aspects first concern the modeling of heat exchange between electrons and phonons reservoirs (YBaCuO and its substrate). Our results establish the optimum operating conditions in terms of dimensions of the constriction and the local oscillator power required for high performance THz mixing (conversion gain and noise temperature). We are introducing in particular a new "hot spot" modeling approach, which takes into account the influence of the terahertz frequency in the YBaCuO material and the impedance matching between the antenna and the constriction. Second, we have developed and optimized the HEB micro-fabrication process in clean room, especially the electronic and optical lithography steps, to obtain constrictions of 300 nm lateral size. Our first devices have been tested by direct detection in the infrared. The performance between YBaCuO ultrathin films prepared using various techniques are compared.
82

Posouzení životnosti svařované žebrované hřídele generátoru / Lifetime Prediction of the Welded Ribbed Generator Shaft

Ryšánek, Michal January 2015 (has links)
This master thesis deals primarily with the prediction of fatigue life of welded ribbed shaft. Recommendations taken from the International Institute of Welding (IIW) are used to express the stress values and the fatigue life. The stress values of examined place are expressed by approach of nominal stress, structural hot spot stress and effective notch stress. Results from stress-strain analysis are combined together with fatigue strength curves for prediction of the fatigue life. At the end of the analysis, the predicted fatigue life is compared with design life of welded ribbed shaft.
83

Optimization of the tribological contact of valve plate and cylinder block within axial piston machines

Geffroy, Stefan, Bauer, Niklas, Mielke, Tobias, Wegner, Stephan, Gels, Stefan, Murrenhoff, Hubertus, Schmitz, Katharina 25 June 2020 (has links)
In this paper, a simulation study is carried out for the development of concepts to optimize the tribological contact of valve plate and cylinder block in an axial piston machine in swash plate design. The valve plate/cylinder block contact is one of the three essential tribological contacts in axial piston machines. In a research project at the Institute for Fluid Power Drives and Systems (ifas), this contact is investigated by a specifically designed simulation tool. In addition, a test rig exists for the experimental investigation. With the results of simulation and experiment, it was shown before that the cylinder block is tilting to the high pressure side. Due to this movement, the gap height is not constant. In the area of minimum gap height, not only the fluid friction, but also the danger of solid body friction increases. Because of the higher friction losses in the area of minimum gap height, the temperature increase reduces the lifetime of the leaded coatings. In this paper, the results of the measurements as well as the simulation model are briefly summarized. It is followed by a simulation study of different possibilities to raise the gap height. Based on this pre-study, a first concept for the optimization of the tribological contact valve plate/cylinder block is presented and its applicability is discussed.
84

ResPublica/Civitas Socialis – Strachotín, l. p. 2017 / ResPublica/Civitas Socialis - Strachotín

Dušková, Barbora January 2017 (has links)
The main goal of this project is to fill the potential of the place, that is hidden behind the church wall. A proposal that will benefit not only the place itself but also the village community and visitors. A project that revives the spirit of the place but preserves its intimate atmosphere. The design itself includes a bistro, an art gallery, accommodation with sauna and a wine gallery. Between all of this is a Provence-style garden.
85

Schule und Kirche : Zusammenhang von Schulentwicklung und christlicher Gesellschaftsverantwortung in dem sozialen Brennpunkt Berlin-Moabit / School and church : interrelations of secular school development and Christian responsibility for community transformation in the deprived area Berlin Moabit

Rauhut, Irene 11 1900 (has links)
Text in German / In dieser Forschungsarbeit wird der Zusammenhang von christlicher Gesellschaftsverantwortung und Schulentwicklung in dem sozialen Brennpunkt Berlin- Moabit untersucht. Aufgrund des anhaltenden Wegzugs bildungsorientierter Eltern mit schulpflichtigen Kindern und damit einer zunehmenden Entmischung (Segregation) der Schülerpopulation und damit des Ortsteils Moabit, möchte die qualitative Studie einen Beitrag dazu leisten, Wege aus dieser schulischen Krise, die Auswirkungen auf die Kirchen Moabits und den Ortsteil insgesamt hat, zu finden. Als Lösungsansatz wird dabei das Bleiben von bildungsorientierten Familien in Moabit mit einer aktiven Kirchenzugehörigkeit aus folgenden Gründen verfolgt: Bleiben bildungsorientierte Familien wieder verstärkt in Moabit wohnen und gehen ihre Kinder auf die ihnen zugewiesenen Grundschulen, so werden durch eine Aufhebung der Segregation die Bildungschancen erhöht, da schulisches Lernen bedeutend auf dem Prinzip des Voneinander Lernens basiert, wie dies zahlreiche Studien belegen. Bleiben Familien mit aktiver Kirchenzugehörigkeit in dem sozialen Brennpunkt Berlin- Moabit wohnen, so können sie in gegenseitiger Unterstützung durch eine missionalinkarnatorische Art zu leben, d.h. durch ein am Vorbild Jesu orientiertes Wohnen und Leben unter den Menschen, Transformation in dem sozial benachteiligten Ortsteil Moabit bewirken. Somit werden Eltern befragt, deren Kinder sich im schulpflichtigen Alter befinden und die das Ziel verfolgen, langfristig in Moabit wohnen zu bleiben, die bereits Moabit aufgrund der Schulsituation verlassen haben oder die vor dieser Entscheidung stehen. Durch diese qualitative Studie, die sich im Kontext der Missionswissenschaften bewegt und der empirischen Theologie zuzuordnen ist, werden Lösungsmöglichkeiten für die Situation in dem Ortsteil Moabit erwartet. / The Thesis explores the connection between Christian social responsibility and public school development in the social hot spot of Berlin-Moabit. Due to the ongoing move away of education-oriented parents with their school-aged children, Moabit suffers from an increasing segregation in its student population and consequently also in its overall population. The present qualitative study seeks to suggest a solution to this schooling crisis that impacts both the churches in Moabit as well as the entire community. The approach to the segregation dilemma in Moabit that this study proposes is for educationoriented families who are also active church members to deliberately remain living in Moabit. This approach is based on two rationales: (1) If education-oriented families increasingly remain in Moabit and send their children to the respectively assigned public schools, segregation can be halted and the overall educational opportunities of all school children will be raised, since school learning strongly draws upon the principle of mutual learning, as many studies have documented. (2) If families who are active church members deliberately remain living in the social hot spot of Moabit, they can support each other to live their lives in a missional incarnation-oriented way, following the pattern of Christ. That way they can eventually initiate a process of transformation in the socially disadvantaged community of Moabit. In accordance with the outlined approach parents of school-aged children are interviewed, who either intend to stay in Moabit, or who have already moved away from Moabit because of the schooling situation, or who are currently confronted with the decision to stay or move. The present qualitative study, that is situated in the missiological field and can be ascribed to the range of empirical Theology, expects to find specific solutions for the above outlined problem in Moabit. / Christian Spirituality, Church History & Missiology / M. Th. (Missiology)
86

Experimentelle und numerische Untersuchungen zur Ausbreitung von Volumenstörungen in thermischen Plumes. / Experimental and numerical studies of the propagation of volume disturbances in thermal plumes.

Laudenbach, Nils 14 December 2001 (has links)
No description available.
87

Schule und Kirche : Zusammenhang von Schulentwicklung und christlicher Gesellschaftsverantwortung in dem sozialen Brennpunkt Berlin-Moabit / School and church : interrelations of secular school development and Christian responsibility for community transformation in the deprived area Berlin Moabit

Rauhut, Irene 11 1900 (has links)
Text in German / In dieser Forschungsarbeit wird der Zusammenhang von christlicher Gesellschaftsverantwortung und Schulentwicklung in dem sozialen Brennpunkt Berlin- Moabit untersucht. Aufgrund des anhaltenden Wegzugs bildungsorientierter Eltern mit schulpflichtigen Kindern und damit einer zunehmenden Entmischung (Segregation) der Schülerpopulation und damit des Ortsteils Moabit, möchte die qualitative Studie einen Beitrag dazu leisten, Wege aus dieser schulischen Krise, die Auswirkungen auf die Kirchen Moabits und den Ortsteil insgesamt hat, zu finden. Als Lösungsansatz wird dabei das Bleiben von bildungsorientierten Familien in Moabit mit einer aktiven Kirchenzugehörigkeit aus folgenden Gründen verfolgt: Bleiben bildungsorientierte Familien wieder verstärkt in Moabit wohnen und gehen ihre Kinder auf die ihnen zugewiesenen Grundschulen, so werden durch eine Aufhebung der Segregation die Bildungschancen erhöht, da schulisches Lernen bedeutend auf dem Prinzip des Voneinander Lernens basiert, wie dies zahlreiche Studien belegen. Bleiben Familien mit aktiver Kirchenzugehörigkeit in dem sozialen Brennpunkt Berlin- Moabit wohnen, so können sie in gegenseitiger Unterstützung durch eine missionalinkarnatorische Art zu leben, d.h. durch ein am Vorbild Jesu orientiertes Wohnen und Leben unter den Menschen, Transformation in dem sozial benachteiligten Ortsteil Moabit bewirken. Somit werden Eltern befragt, deren Kinder sich im schulpflichtigen Alter befinden und die das Ziel verfolgen, langfristig in Moabit wohnen zu bleiben, die bereits Moabit aufgrund der Schulsituation verlassen haben oder die vor dieser Entscheidung stehen. Durch diese qualitative Studie, die sich im Kontext der Missionswissenschaften bewegt und der empirischen Theologie zuzuordnen ist, werden Lösungsmöglichkeiten für die Situation in dem Ortsteil Moabit erwartet. / The Thesis explores the connection between Christian social responsibility and public school development in the social hot spot of Berlin-Moabit. Due to the ongoing move away of education-oriented parents with their school-aged children, Moabit suffers from an increasing segregation in its student population and consequently also in its overall population. The present qualitative study seeks to suggest a solution to this schooling crisis that impacts both the churches in Moabit as well as the entire community. The approach to the segregation dilemma in Moabit that this study proposes is for educationoriented families who are also active church members to deliberately remain living in Moabit. This approach is based on two rationales: (1) If education-oriented families increasingly remain in Moabit and send their children to the respectively assigned public schools, segregation can be halted and the overall educational opportunities of all school children will be raised, since school learning strongly draws upon the principle of mutual learning, as many studies have documented. (2) If families who are active church members deliberately remain living in the social hot spot of Moabit, they can support each other to live their lives in a missional incarnation-oriented way, following the pattern of Christ. That way they can eventually initiate a process of transformation in the socially disadvantaged community of Moabit. In accordance with the outlined approach parents of school-aged children are interviewed, who either intend to stay in Moabit, or who have already moved away from Moabit because of the schooling situation, or who are currently confronted with the decision to stay or move. The present qualitative study, that is situated in the missiological field and can be ascribed to the range of empirical Theology, expects to find specific solutions for the above outlined problem in Moabit. / Christian Spirituality, Church History and Missiology / M. Th. (Missiology)
88

臺北市公共自行車站點需求分析之研究 / A research in the demand of the public bike station in Taipei.

張辰尉 Unknown Date (has links)
近年來由於溫室效應加劇以及氣候變遷加劇,因此符合綠色運輸特性的公共自行車系統,成為各國交通部門發展綠運輸政策時的目標之一,同時,大數據分析亦是目前受到高度關注的熱門議題。而本研究首先使用臺北市微笑單車租借大數據探討在不同時間點下民眾日常使用微笑單車之旅運行為,分析不同站點間的旅次特性。再運用社群網絡分析,以站點之間旅次連結多寡作為權重,探討站點間之緊密程度,以及不同時間點下微笑單車租借量之熱點分布情形,並將其視覺化呈現。 後續透過文獻分析,擷取影響公共自行車使用量之因素後,本研究嘗試運用一般線性迴歸模型與地理加權迴歸進行模型建立,並探討各影響因素對於旅運需求之影響情形。實證結果顯示,地理加權迴歸模型可以解決一般線性迴歸所產生空間自相關問題,使得模型解釋能力獲得改善。本研究並使用地理加權迴歸進行使用需求分析以及預測,對未來公共自行車營運以及站點擴張提出結論以及建議,期能提升公共自行車系統之使用量。 / Due to the climate change and aggravation of the greenhouse effect in recent years, the public bicycle system with the feature of low-carbon emission has raised more and more attention internationally, and has become one of the targets in developing green transportation policies of transportation departments of governments around the world. Meanwhile Big Data analysis issues, on the other hand, are currently a sought-after topic which has caused great concern as well. In this study, we utilize the rental data of the YouBike system in Taipei to discuss the public usage of YouBike tour at different periods. With the use of social network analysis, we discuss the relationships between different bicycle stops based on applying the number of travels between different sites as the weight. Eventually, the hotspot analysis will be carried out by operating the GIS system. In this way, we are able to discuss the hotspot distribution of YouBike rentals in different time and then visualize the result. After that this study pick up the variables which will effect the YouBike usage by reference review. This research try to built models by utilizing the Least Squares Method and Geographically Weighted Regression. Then we will have a discussion with the result of the two models. The result shows that Geographically Weighted Regression can resolve the spatial autocorrelation problem which happened in the Least Squares Method and to gain a better result. With the analysis and prediction of public bicycle system from Geographically Weighted Regression, we hope to raise the usage of public bicycle system by concluding as well as making recommendations for the future operation of public bicycle and the expansion of bicycle stops.
89

Spatial Modelling of Gastroenteritis Prevalence Following the February 22, 2011 Earthquake and Identification of Successful Factors Preventing Outbreaks at Emergency Centres

Chandratilake (nee Weerasekara), Sonali Evanjali January 2013 (has links)
The potential for a gastroenteritis outbreak in a post-earthquake environment may increase because of compromised infrastructure services, contaminated liquefaction (lateral spreading and surface ejecta), and the presence of gastroenteritis agents in the drinking water network. A population in a post-earthquake environment might be seriously affected by gastroenteritis because it has a short incubation period (about 10 hours). The potential for a gastroenteritis outbreak in a post-earthquake environment may increase because of compromised infrastructure services, contaminated liquefaction (lateral spreading and surface ejecta), and the presence of gastroenteritis agents in the drinking water network. A population in a post-earthquake environment might be seriously affected by gastroenteritis because it has a short incubation period (about 10 hours). The aim of this multidisciplinary research was to retrospectively analyse the gastroenteritis prevalence following the February 22, 2011 earthquake in Christchurch. The first focus was to assess whether earthquake-induced infrastructure damage, liquefaction, and gastroenteritis agents spatially explained the recorded gastroenteritis cases over the period of 35 days following the February 22, 2011 earthquake in Christchurch. The gastroenteritis agents considered in this study were Escherichia coli found in the drinking water supply (MPN/100mL) and Non-Compliant Free Associated Chlorine (FAC-NC) (less than <0.02mg/L). The second focus was the protocols that averted a gastroenteritis outbreak at three Emergency Centres (ECs): Burnside High School Emergency Centre (BEC); Cowles Stadium Emergency Centre (CEC); and Linwood High School Emergency Centre (LEC). Using a mixed-method approach, gastroenteritis point prevalence and the considered factors were quantitatively analysed. The qualitative analysis involved interviewing 30 EC staff members. The data was evaluated by adopting the Grounded Theory (GT) approach. Spatial analysis of considered factors showed that highly damaged CAUs were statistically clustered as demonstrated by Moran’s I statistic and hot spot analysis. Further modelling showed that gastroenteritis point prevalence clustering could not be fully explained by infrastructure damage alone, and other factors influenced the recorded gastroenteritis point prevalence. However, the results of this research suggest that there was a tenuous, indirect relationship between recorded gastroenteritis point prevalence and the considered factors: earthquake-induced infrastructure damage, liquefaction and FAC-NC. Two ECs were opened as part of the post-earthquake response in areas with severe infrastructure damage and liquefaction (BEC and CEC). The third EC (CEC) provided important lessons that were learnt from the previous September 4, 2010 earthquake, and implemented after the February 22, 2011 earthquake. Two types of interwoven themes identified: direct and indirect. The direct themes were preventive protocols and indirect themes included type of EC building (school or a sports stadium), and EC staff. The main limitations of the research were Modifiable Areal Units (MAUP), data detection, and memory loss. This research provides a practical method that can be adapted to assess gastroenteritis risk in a post-earthquake environment. Thus, this mixed method approach can be used in other disaster contexts to study gastroenteritis prevalence, and can serve as an appendage to the existing framework for assessing infectious diseases. Furthermore, the lessons learnt from qualitative analysis can inform the current infectious disease management plans, designed for a post-disaster response in New Zealand and internationally Using a mixed-method approach, gastroenteritis point prevalence and the considered factors were quantitatively analysed. A damage profile was created by amalgamating different types of damage for the considered factors for each Census Area Unit (CAU) in Christchurch. The damage profile enabled the application of a variety of statistical methods which included Moran’s I , Hot Spot (HS) analysis, Spearman’s Rho, and Besag–York–Mollié Model using a range of software. The qualitative analysis involved interviewing 30 EC staff members. The data was evaluated by adopting the Grounded Theory (GT) approach. Spatial analysis of considered factors showed that highly damaged CAUs were statistically clustered as demonstrated by Moran’s I statistic and hot spot analysis. Further modelling showed that gastroenteritis point prevalence clustering could not be fully explained by infrastructure damage alone, and other factors influenced the recorded gastroenteritis point prevalence. However, the results of this research suggest that there was a tenuous, indirect relationship between recorded gastroenteritis point prevalence and the considered factors: earthquake-induced infrastructure damage, liquefaction and FAC-NC. Two ECs were opened as part of the post-earthquake response in areas with severe infrastructure damage and liquefaction (BEC and CEC). The third EC (CEC) provided important lessons that were learnt from the previous September 4, 2010 earthquake, and implemented after the February 22, 2011 earthquake. The ECs were selected to represent the Christchurch area, and were situated where potential for gastroenteritis was high. BEC represented the western side of Christchurch; whilst, CEC and LEC represented the eastern side, where the potential for gastroenteritis was high according to the outputs of the quantitative spatial modelling. Qualitative analysis from the interviews at the ECs revealed that evacuees were arriving at the ECs with gastroenteritis-like symptoms. Participants believed that those symptoms did not originate at the ECs. Two types of interwoven themes identified: direct and indirect. The direct themes were preventive protocols that included prolific use of hand sanitisers; surveillance; and the services offered. Indirect themes included the EC layout, type of EC building (school or a sports stadium), and EC staff. Indirect themes governed the quality and sustainability of the direct themes implemented, which in turn averted gastroenteritis outbreaks at the ECs. The main limitations of the research were Modifiable Areal Units (MAUP), data detection, and memory loss. It was concluded that gastroenteritis point prevalence following the February 22, 2011 earthquake could not be solely explained by earthquake-induced infrastructure damage, liquefaction, and gastroenteritis causative agents alone. However, this research provides a practical method that can be adapted to assess gastroenteritis risk in a post-earthquake environment. Creating a damage profile for each CAU and using spatial data analysis can isolate vulnerable areas, and qualitative data analysis provides localised information. Thus, this mixed method approach can be used in other disaster contexts to study gastroenteritis prevalence, and can serve as an appendage to the existing framework for assessing infectious diseases. Furthermore, the lessons learnt from qualitative analysis can inform the current infectious disease management plans, designed for a post-disaster response in New Zealand and internationally.

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