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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

Messung von Impulsflüssen in der Mesosphäre / unteren Thermosphäre mit dem SKiYMET Meteorradar in Collm – Methode und erste Ergebnisse

Placke, M., Jacobi, Ch, Stober, G. 17 August 2017 (has links)
Schwerewellen transportieren Energie und Impuls aus den unteren in die oberen Atmosphärenschichten. Impulsflüsse und ihre Divergenz beschreiben dabei die Kopplung der Wellen mit der mittleren Zirkulation. Mit einer Methode von Hocking (2005) können Varianzen und Schwerewellenimpulsflüsse in der Mesosphäre / unteren Thermosphäre mit einem All-Sky Interferometric (SKiYMET) Meteorradar bestimmt werden. Diese Methode wurde auf die Datensätze des Meteorradars in Collm (51.3°N,13.0°E) angewandt. Erste Ergebnisse für die Varianzen und Impulsflüsse sowie speziell für die Höhenprofile des vertikalen Flusses zonalen Impulses im Jahresgang und die Untersuchung dessen auf periodische Schwankungen werden hier vorgestellt. / Gravity waves transport energy and momentum from the lower to the upper atmosphere. Momentum fluxes and their divergence describe the coupling of the waves with the background circulation. By using a method presented by Hocking (2005), wind variances and gravity wave momentum fluxes in the mesosphere/lower thermosphere can be determined with an all-sky interferometric (SKiYMET) meteor radar. This method has been applied to the data sets of the meteor radar at Collm (51.3°N,13.0°E). First results for the variances and momentum fluxes as well as for the height profiles of the vertical flux of zonal momentum, its seasonal cycle and periodic variations are presented.
82

Active Lateral Secondary Suspension in a High-Speed Train to Improve Ride Comfort

Orvnäs, Anneli January 2009 (has links)
Active secondary suspension in trains has been studied for a number of years, showing promising improvements in ride comfort. However, due to relatively high implementation and maintenance costs, active technology is not being used in service operation to a large extent. The objective of this study is to develop an active lateral secondary suspension concept that offers good ride comfort improvements and enables centring of the carbody above the bogies when negotiating curves at unbalanced speed. Simultaneously, the active suspension concept should be a cost-effective solution for future series production. The thesis consists of an introductory part and three appended papers. The introductory part describes the concept of active secondary suspension together with different actuator types and control methods. Further, the present simulation model and applied comfort evaluation methods are presented. The introductory part also comprises a summary of the appended papers, an evaluation of track forces and suggestions for further work. Paper A presents the initial development of an active lateral secondary suspension concept based on sky-hook damping in order to improve vehicle dynamic performance, particularly on straight tracks. Furthermore, a Hold-Off-Device (HOD) function has been included in the suspension concept in order to centre the carbody above the bogies in curves and hence avoid bumpstop contact. Preparatory simulations as well as the subsequent on-track tests in the summer of 2007 showed that the active suspension provides improved passenger ride comfort and has significant potential to be a cost-effective solution for future implementation. In Paper B, measurement results from on-track tests performed in 2008 are presented. The active secondary suspension concept was slightly modified compared to the one presented in the first paper. One modification was the implementation of a gyroscope in order to enable detection of transition curves and to switch off the dynamic damping in these sections. Ride comfort in the actively suspended carbody was significantly improved compared to that in the passively suspended car. The satisfactory results led to implementation of the active suspension system in long-term tests in service operation in the beginning of 2009. In Paper C, a quarter-car model in MATLAB has been used to investigate a more advanced control algorithm: H∞ instead of sky-hook. H∞ control provides more flexibility in the design process due to the possibility to control several parameters. In particular, this is done by applying weight functions to selected signals in the system. When comparing the two control strategies through simulations, the results show that H∞ control generates similar carbody accelerations at the same control force as sky-hook; however, the relative displacement displacement is somewhat lower.
83

Impact of Climate Variability on the Frequency and Severity of Ecological Disturbances in Great Basin Bristlecone Pine Sky Island Ecosystems

Gray, Curtis A 01 May 2017 (has links)
Great Basin bristlecone pine (GBBP) (Pinus longaevaBailey) is one of the longest-lived organisms on Earth, and is one of the most highly fragmented high elevation conifer species. Throughout the Great Basin of the Intermountain West, GBBP are being impacted by changing disturbance regimes, invasive species, and climate change. To better understand the effects of climate variability and ecological disturbances in GBBP systems, three studies were designed and implemented. The first characterized the distribution of forest fuel in stands of GBBP and predicted how fuels may change under future climate scenarios. Using the Forest Inventory Analysis (FIA) plot variables of tree species, height, diameter at breast height (DBH), canopy base height (CBH), coarse (CWD) and fine (FWD) woody debris across elevational gradients, this study examined the effects of changes to fuel loading on predicted changes in fire behavior and severity. All classes of FWD decreased with elevation, and only 1000-hr fuels remained constant across elevational transects. This, combined with lower CBH and foliar moisture and increasing temperatures due to climate change, suggested increased fire potential at the GBBP treeline. The second study examined the role of volatile organic compounds (VOCs) and tree chemistry and their response to the environment. VOCs and within needle chemistry were collected and analyzed along elevational gradients near the northern and southern limits of GBBP. Random Forest analysis distinguished elevation using VOCs, with 83% accuracy, and identified the compounds most important for classification. Ordination revealed that temperature, heat load index, and relative humidity were each significantly correlated with VOCs. Within-needle chemistry provided less predictive value in classifying elevation (68% accuracy) and was correlated only with heat load index. These findings suggest that GBBP VOCs are highly sensitive to the environment. The final study explored the role of VOCs in host selection of mountain pine beetle (MPB). Mountain pine beetles oriented toward VOCs from host limber pine (Pinus flexilis James) and away from VOCs of non-host GBBP using a Y-tube olfactometer. When presented with VOCs of both trees, females overwhelmingly chose limber pine over GBBP. While there were only a few notable differences in VOCs collected from co-occurring GBBP and limber pine, 3-carene and D-limonene were produced in greater amounts by limber pine. There was no evidence that 3-carene is important for beetles when selecting trees, however, addition of D-limonene to GBBP VOCs disrupted the ability of beetles to distinguish between tree species. Climate change will impact how forests are managed and this research could provide insight into the mechanisms underlying the incredible longevity of this iconic tree species.
84

A New Mass Measurement for Galaxy Clusters Using Position and Radial Velocity

Fultz, Kayla Jo January 2010 (has links)
No description available.
85

A Historical Study of "The Railroad in the Sky"

Wise, Robert Lee 01 January 1973 (has links) (PDF)
Taken from the introduction: This investigation is concerned with the history of Bodie, California as a mining town and will cover briefly a history of the area before going into the main body of the paper which will research the railroad that served the mining camps of the Bodie area, as well as briefly researching neighboring railroads, to show the roles they played in the building up of this east of the Sierras town. This paper will also go into the politicing and business maneuvering of the Bodie Railroad in an effort to get connections with outside rails -- a necessity if the railroad was to survive. It will also cover the roles played by outside railroads in an effort to limit the Bodie Railroad to its own tracks. In short it will show why the railroad was built and why it could not survive.
86

Improving Daylight Qualities in Medelhavsmuseet

Khairy Al Madhoon, Nada January 2019 (has links)
The master’s thesis investigates daylight qualities and visitors’ perception in the central atriumof Medelhavsmuseet in Stockholm, Sweden. The investigation started from personal observationof the space where a feeling of darkness was experienced despite the existing skylight.The visitors’ perception of daylight and space were examined through a survey, and it wascompared to daylight simulations where it was proven that the museum’s daylight quality couldbe classified as a minimum. It is suspected that visitor perception of the space was consideredto be bright due to the use of artificial light, and the brightness of the prevailing weather conditionsduring the time of the survey (mid-April). The daylight conditions as per the survey andsimulations are considered to be sufficient if not a little muted during the lighter half of the year,but during the darker seasons, they are likely to be insufficient. Furthermore, it is proposed thatre-designing the skylight, changing the way the artwork is displayed or changing the materialof the skylight could drastically improve daylight quality, in turn benefiting visitor experience.
87

Seeing Double? The Remaking of A Amenábar's Abre Los Ojos as Cameron Crowe's Vanilla Sky.

White, Anne M. January 2003 (has links)
No / This article begins by examining in general terms the remaking of European films by Hollywood and considers the reasons for the growth in this cultural phenomenon. It goes onto argue that analysis of this process has much to tell us about intertextuality: how texts are read and transformed. Focusing on Vanilla Sky (US 2002), the Hollywood remake by Cameron Crowe of Alejandro Amenábar's film, Abre los ojos (Spain 1997), it explores the similarities and differences between the two films. In addition, it also considers the extent to which a filmic remake like Vanilla Sky might be read as a self-conscious reflection on the processes which are at the very heart of intertextuality as we understand it.
88

A Shield in the Sky: The Vertical Geopolitics of Transcontinental Air Defense

Davitch, James Michael 04 May 2023 (has links)
Doctor of Philosophy / Traditional military descriptions of conflict tend to focus on the movement of soldiers and armies across battlefields. When the airplane emerged, it forced military theorists to contend with a new, vertical, dimension of conflict. In America, the United States Air Force assumed an important role in this vertical dimension as the country's delivery mechanism for nuclear weapons. However, at the same time that politicians, academics, and military officials debated the offensive uses for aircraft a second debate occurred describing how best to use military means to defend the North American continent. Those who advocated for a defensive system to protect North American, including the President Eisenhower, strongly advocated for a continent-wide test of the new air defense system. That test was conducted once a year between 1960 and 1962 during which all civilian air travel across the U.S. and Canada was suspended. The tests were called the "Sky Shield" exercises. This research shows how a prevailing mood of fear and vulnerability gave air defense proponents the political capital to build a continental air defense network and test it during the Sky Shield exercises. Further, it describes the enduring legacy of this domestically-focused Cold War defense program. The research finds that America's approach to Cold War continental defense was strong when it was aligned with the White House's nuclear strategy, but when successive political leaders changed nuclear strategies that decision negatively influenced continental defense programs. This research is useful because it examines a relatively under-explored area of Cold War defense programs. Traditionally these studies focus on offensive capabilities far from American shores. This study instead examines homeland defense and how it changed during the Cold War as a function of changing nuclear programs and changing threats to the United States.
89

Parallel evaluation of Doxorubicin inducing Genetic damage in human lymphocytes and sperm using the Comet assay and spectral karyotyping

Anderson, Diana, Baumgartner, Adolf, Cemeli, Eduardo, Schmid, Thomas E. January 2004 (has links)
No / In recent years, two techniques for detecting genetic damage in the whole genome have gained importance: the alkaline comet assay, to detect DNA damage such as strand breaks and alkali-labile sites, and a multicolour FISH method, spectral karyotyping (SKY), to identify chromosomal aberrations simultaneously in all metaphase chromosomes. In the present study, the induction of DNA damage in human sperm and lymphocytes in vitro has been studied employing an anticancer drug, doxorubicin (DX). An increase in DNA damage was observed with the comet assay as the median per cent head DNA of sperm significantly decreased from 82.07 and 85.14% in the untreated control groups to 63.48 and 72.52% at doses of 0.8 µM DX. At 1.6 µM the percentage declined to 60.96% (the corresponding tail moment increased from 4.42 to 12.19). In stimulated lymphocytes, a significant increase was observed in tail moment, from 0.72 and 0.53 in controls to 15.17 and 12.10 at 0.2 µM DX, continuing at the same level to a final concentration of 1.6 µM. Structural aberrations found in the parallel SKY study in stimulated lymphocytes at 0.2 µM DX consisted of 14% chromatid-type and 2% chromosome-type aberrations; none were found in controls. The SKY results correlate very well with the findings of the comet assay in lymphocytes where DNA damage was observed at similar doses. This study is the first reporting use of the comet assay and SKY analysis in parallel after chemical treatment. The potential of the two techniques together is evident, as they represent a set of assays feasible for evaluating damage in human somatic and germ cells after chemical treatment (i) by direct observation of two different end-points, detecting general DNA damage and chromosomal aberrations and (ii) by extrapolation from lymphocytes to sperm, which provides a `parallelogram¿ approach in human cells.
90

Proměny zobrazení československých pilotů v české filmové tvorbě / Image transformation of czechoslovakian pilots in selected czech films

Janů, Adéla January 2017 (has links)
This thesis analyses image of Czechoslovakian pilots in local film production. It focuses on films about pilots from Second World War and pilots from Czechoslovak people's army. The aim of thesis is to define main characteristics of military pilots in selected films and compare their transformation through time. Analytic part will use visual, semiotic, discursive and narrative analysis concept as theoretical framework. Thesis works on the presumption that image transformation was highly influenced by historical and political development of country. It assumes that pilots from Second World War were portrayed positively in late 1960s and after year 1989 and pilots from Czechoslovak people's army were favored in era of normalization, particularly in 1970s and 1980s.

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