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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.
101

Star Shaped Thieno- and Thienylaryls as Multifunctional Materials

Robertson, Sean January 2015 (has links)
The work in this thesis was undertaken to explore both the effect of heteroatoms on the semiconducting properties of star-shaped thienoacenes, and to expand the scope of these materials to fields outside of organic semiconductors. Overall, new star-shaped molecules were prepared with a view towards applications such as thin film transistors, as the organic linker component in metal-organic frameworks, and as ligands that could coordinate to transition metals through the sulfur atom. The first chapter describes the properties of star-shaped molecules, the theory underlying their semiconducting behaviour, and the previous work that motivated the research contained herein. The second chapter of this thesis outlines the synthetic methodology that was utilized to achieve the molecular targets, as well as the characterization techniques that are used to reveal the properties of organic semiconductors. The third chapter of this thesis describes the synthesis and optoelectronic properties of novel nitrogen-containing semiconductor molecules called thienoacridines, and their comparison to carbon-and-sulfur based analogues, thienoanthracenes. The fourth and fifth chapters concern the synthesis of functionalized star shaped thienylbenzene molecules. In Chapter 4, these molecules are decorated with carboxylic acid groups so that they may act as tetrapodal MOF linkers. In Chapter 5, they are equipped with N-aryl(azomethine)thiophene moieties to explore sulfur coordination and act as ligands. The sixth chapter provides conclusion to this work, and possible future directions of the research conducted herein.
102

Ring-array photoacoustic tomography for imaging human finger vasculature / 人の指血管イメージングのためのリングアレイ光超音波トモグラフィ

Nishiyama, Misaki 23 March 2021 (has links)
付記する学位プログラム名: 充実した健康長寿社会を築く総合医療開発リーダー育成プログラム / 京都大学 / 新制・課程博士 / 博士(人間健康科学) / 甲第23127号 / 人健博第89号 / 新制||人健||6(附属図書館) / 京都大学大学院医学研究科人間健康科学系専攻 / (主査)教授 杉本 直三, 教授 黒木 裕士, 教授 松田 秀一 / 学位規則第4条第1項該当 / Doctor of Human Health Sciences / Kyoto University / DFAM
103

Dělící zařízení tyčí z barevných kovů / Dividing equipment for bars made of non-ferrous metals

Strašák, Milan January 2012 (has links)
The aim of this master´s thesis is to design solution of equipment for dividing rods of non-ferrous metals. The equipment is primarily meant for innovation of semi-finished product preparation in blacksmith's workshop. This master´s thesis mainly focused on design of individual mechanical components of alligator shears and their calculations. There are also solved dangerous places for operators and surroundings by using a safety analysis. The result of this master´s thesis is possibility of design mechanical part according to assignment.
104

Technologie výroby tvarové součásti víceosým CNC obráběním / On the production technology of a shaped part with multi-axis machining

Kopcík, Daniel January 2015 (has links)
The theoretical part of this thesis is introducing basic information in production of shaped components on CNC machines. It describes each steps from a design of the component to production. Main target is summarization of available modern technologies that can be used. Experimental part uses these modern technologies for processing design shaped component. It describes process of design 3D model part in CAD system, subsequently creation of program for machining in CAM system and solves production of part on CNC machine. The aim of this thesis is design part with interesting design and production difficult enough to represent company, where it was made.
105

Diffusion d'un faisceau modelé par une sphère excentrique et propriétés du sphéroïde / Shaped beam scattering by an eccentric particle and Rainbow properties of spheroids

Wang, Jiajie 24 September 2011 (has links)
Deux pièces de travail sont inclus dans cette thèse. La première partie analyse l'interaction d'une sphère excentrique avec un faisceau incident quelconque formé dans le cadre de généralisé de la théorie de Lorenz-Mie (generalized Lorenz-Mie theory, GLMT). Distributions de contrôle interne, près de la surface, loin des champs dispersés zone ainsi que le comportement de la morphologie dépendant résonances (MDR) dans une sphère excentrique éclairée par un faisceau focalisé guassien sont analysés. Dans la seconde partie, en utilisant l'EBCM, les propriétés de diffusion de lumière autour de l'angle arc pour un ensemble de sphéroïdes dans des orientations aléatoires éclairé par une onde plane sont étudiés. En comparant les paramètres extraits de ces paramètres originaux utilisés dans les expériences de simulation, la sensibilité de la technique d'arc de la sphéricité des gouttelettes non est quantifié. / Two parts of this work are included in this thesis. The first part analyses the interaction of an eccentric particle with an arbitrary incident shaped beam within the generalized Lorenz-Mie theory (GLMT). Distributions of internal, near-surface, far-zone scattered fields as well as the behavior of morphlogy-dependent resonances (MDRs) in an eccentric sphere illuminated by a focused Gaussian beam are analysed. In the second part, by using the ECBM, light scattering properties around the rainbow angle for an ensemble of spheroids in random orientations illuminated by a plane wave are studied. By comparing the extracted parameters with those original parameters used in the simulation experiments, the sensitivity of the rainbow technique to the non-sphericity of droplets is quantified.
106

An in Vitro investigation of the effects of Rimonabant (a cannabinoid CB1 receptor antagonist) on cell adhesion and inflammatory associated cytokine production

Bouwer, Adoree 09 May 2013 (has links)
There is good pharmacological evidence that cannabinoids caused cellular changes by interacting with specific cannabinoid receptors (CBR) (Klein et al., 2000). To date, two CBRs have been identified in the human body, designated Cannabinoid Receptor 1 (CB1) and Cannabinoid Receptor 2 (CB2) (Begg et al., 2005). Endogenously occurring compounds with action at the CBRs also exist and they are called endocannabinoids. One of the four known endocannabinoids is anandamide (AEA). The endocannabinoid system, present in the human body, plays a significant role in altering the physiology of the immune system. Enhancement of this system’s anti-inflammatory effect could possibly present a vital therapeutic target for central and peripheral inflammatory disorders. A number of synthetic CB1 or CB2 specific antagonists have been developed including the highly specific CB1 receptor antagonist/reverse agonist named Rimonabant/ SR141716A. SR compounds are considered unique because these compounds not only inhibit the binding and function of cannabimimetic agents, but also act as inverse agonists. Activation of CB1 receptors produces inappropriate CNS side effects including psychoactivity, dependence and sedation (Clayton et al., 2002) whereas CB1 receptor antagonists/inverse agonists avoid or prevent these side effects. Taking the above information into consideration, Rimonabant has the potential to offer an effective long term treatment of chronic inflammatory disorders without the serious side effects of commonly used treatments. The main aim of this study is to investigate the in vitro effects of Rimonabant alone and in combination with anandamide on inflammatory associated cytokine production by human umbilical vein endothelial cells (HUVEC) and macrophage cultures. After careful consideration of the evidence stating that endothelial cells produce several important molecules vital to the inflammatory response of the body and the confirmation that CB1 receptor mRNA is generally present in endothelial cells, the use of HUVEC was deemed to be satisfactory for this study. The first phase of the study was dedicated to establishing the technique to isolate HUVEC from fresh human umbilical cord within the local laboratory and to maintain these in culture for further use during experimental procedures to test the effects of CB1 ligands. The isolation procedure, trypsinising, freezing away and thawing methods used during this experiment produced healthy HUVEC in sufficient numbers for further use. The next step was to determine the maximum in vitro concentrations at which Rimonabant and anandamide had insignificant cytotoxic effect on selected human cells and in doing so, determine suitable concentrations for further experimentation. Both compounds had a dose related anti-proliferative response when tested on HUVEC. The same dose related response was observed during the Rimonabant exposure to human lymphocytes, but no decrease in lymphocyte viability was observed when treated with anandamide at the concentrations tested. It is evident from the results that there was an almost ten times difference in the IC50 value of the two different products (14.3 μM for Rimonabant and 124.2 μM for anandamide) which was statistically significant. Flow cytometry was used to determine the effects of Rimonabant and anandamide on the surface expression of the CR3 complement receptor by human neutrophils. Neither Rimonabant nor anandamide significantly affect CR3 expression on the surface of freshly isolated human neutrophils and would exclude the CR3 expression pathways as a potential mechanism of action for the anti-inflammatory effects of these compounds. The in vitro effect of Rimonabant and anandamide alone and in combination on the production of cytokines by human macrophages and by HUVEC was determined. Anandamide was shown to inhibit the production of all the detectable cytokines (IL-8, IL-1β and IL-6 in both cell types and IL-10 and TNF-α in macrophages). Furthermore this inhibitory effect was attenuated by pre-treatment Rimonabant. These results would suggest that anandamide could induce anti-inflammatory effects observed in macrophages and HUVEC, through cannabinoid receptors. Rimonabant also inhibited the production of all the detectable cytokines following treatment with 0.5 μM and 3 μM respectively. The anti-inflammatory effects of anandamide were attenuated when combined with 1 μM of Rimonabant. Throughout the various cytokine responses, the dose-response relationship appeared to follow a bell-shaped dose-response. This occurrence proposes that Rimonabant displaces anandamide and blocks the anti-inflammatory effects of the agonist. Flow cytometry was used to determine the effects of Rimonabant and anandamide alone and in combination on the extracellular surface expression of ICAM-1 by HUVEC. Neither Rimonabant nor anandamide had any significant inhibitory effect on the expression of ICAM-1 by HUVEC. Considering the low levels for ICAM-1 expressed by the HUVEC during this experiment and the literature supporting more effective methods of activating the ICAM-1 gene and subsequent up-regulation of ICAM-1 proteins, TNF-α stimulation of HUVEC might produce a different result compared to IL-1β stimulation. The final phase of the project was to determine the effects of Rimonabant and anandamide on the adhesion of human neutrophils to HUVEC. There was no significant difference with relation to the neutrophil adhesion to HUVEC following the treatment with various combination concentrations of the compounds, and also no significant effect following treatment with either test compound individually. Although a specific mechanism of action for Rimonabant could not be uncovered during this study, there is evidence that several possible mechanisms can be excluded. The results support observations made by other researchers and the hypothesis that Rimonabant has anti-inflammatory effects. The results provide motivation for further experimentation to better understand these anti-inflammatory actions of Rimonabant. / Dissertation (MSc)--University of Pretoria, 2012. / Pharmacology / unrestricted
107

Vowel perception in severe noise

Swanepoel, Rikus 05 March 2013 (has links)
A model that can accurately predict speech recognition for cochlear implant (CI) listeners is essential for the optimal fitting of cochlear implants. By implementing a CI acoustic model that mimics CI speech processing, the challenge of predicting speech perception in cochlear implants can be simplified. As a first step in predicting the recognition of speech processed through an acoustic model, vowel perception in severe speech-shaped noise was investigated in the current study. The aim was to determine the acoustic cues that listeners use to recognize vowels in severe noise and make suggestions regarding a vowel perception predictor. It is known that formants play an important role in quiet, while in severe noise the role of formants is still unknown. The relative importance of F1 and F2 is also of interest, since the masking of noise is not always evenly distributed over the vowel spectrum. The problem was addressed by synthesizing vowels consisting of either detailed spectral shape or formant information. F1 and F2 were also suppressed to examine the effect in severe noise. The synthetic stimuli were presented to listeners in quiet and signal-to-noise ratios of 0 dB, -5 dB and -10 dB. Results showed that in severe noise, vowels synthesized according to the whole-spectrum were recognized significantly better than vowels containing only formants. Multidimensional scaling and FITA analysis indicated that formants were still perceived and extracted by the human auditory system in severe noise, especially when the vowel spectrum consisted of the whole spectral shape. Although F1 and F2 vary in importance in listening conditions of quiet and less noisy conditions, the role of the two cues appears to be similar in severe noise. It was suggested that not only the availability formants, but also details of the vowel spectral shape can help to predict vowel recognition in severe noise to a certain degree. / Dissertation (MEng)--University of Pretoria, 2010. / Electrical, Electronic and Computer Engineering / unrestricted
108

Shaped Charge Design : Construction of a Miniaturized Shaped Charge / RSV-design : Konstruktion av en miniatyriserad RSV-laddning

Gustafsson, Andreas January 2021 (has links)
The shaped charges on the market today ranges from about 20 to 200 mm in diameter but there is a need of smaller sizes for example in applications where a small projectile with a high speed is needed or to equip or take out drones with. The objective of this thesis work was to develop a miniaturized shaped charge with dimensions smaller than those available today and preferably with a diameter down to 10 mm. The project was conducted at Karlstad University in collaboration with Saab Dynamics AB. The process used during this project was to start with a feasibility study to obtain information about the limits on dimensions in order to investigate how small dimensions can be used for the casing and liner with respect to manufacturability. The feasibility study was conducted by studying academic literature, contacting companies with expertise within the field of manufacturing. A previously used shaped charge was used as a starting point and the dimensions was scaled in accordance with the objective. The influence of the design parameters was examined using the γSPH module in IMPETUS Afea. The liner material used was restricted to oxygen-free high thermal conductivity copper and different materials for the casing was tested. Two material selections for the casing were made with the aid of Granta Edupack. It has been concluded that it is possible to manufacture a miniaturized shaped charge with dimensions down to about ten mm. Both a design for a jet forming shaped charge and an explosively formed penetrator was developed during the project. The resulting projectile for the explosively formed penetrator had a velocity of 2450 m/s, a total length of 7.3 mm and 3.5 mm in diameter, and the jet forming shaped charge had a jet tip velocity of 7060 m/s and was able to penetrate 38-mm into an AISI 4340 steel target according to the models used in IMPETUS Afea. A prototype was planned but due to cost restrictions, it is left as future work. / Riktad sprängverkan (RSV)-laddningarna som finns på marknaden idag sträcker sig från ungefär 20 till 200 mm i diameter. Det finns dock ett behov för storlekar mindre än detta, till exempel i tillämpningar där en liten projektil med hög fart krävs, alternativt att utrusta eller sänka drönare med. Målet med detta examensarbete var att utveckla en miniatyriserad RSV-laddning med dimensioner mindre än vad som finns tillgängligt idag och helst med en diameter neråt tio mm. Projektet utfördes på Karlstads universitet i samarbete med Saab Dynamics AB. Processen som användes under detta projekt gick ut på att börja med en förstudie for att erhålla information om gränserna för mått för att undersöka hur små dimensioner som kan användas för höljet och linern med avseende på tillverkningsbarhet. Förstudien genomfördes genom att studera akademisk litteratur och kontakta företag med expertis inom tillverkningsområdet. En tidigare använd RSV-laddning användes som startpunkt och dimensionerna justerades i enlighet med målet. Påverkan av parametrar på prestanda undersöktes genom att använda γSPH modulen i IMPETUS Afea. Det använda materialet för linern begränsades till OFHC koppar och olika material för höljet testades. Två materialval gjordes för höljet med hjälp av Granta Edupack. Slutsatsen som kan dras utifrån arbetet är att det är möjligt att tillverka miniatyriserade RSV-laddningar med dimensioner neråt tio mm. Både en design för en strålbildande RSV-laddning och en projektilbildande RSV-laddning utvecklades under projektet. Den resulterande projektilen för den projektilbilande RSV-laddningen hade en fart på 2450 m/s, en längd av totalt 7.3 mm och 3.5 mm i diameter och den strålbildande RSV-laddningen hade en spetsfart på 7060 km/s och kunde penetrera 38 mm AISI 4340 stål enligt modellen som användes i IMPETUS Afea. En prototyp planerades men på grund av kostnadsrestriktioner lämnades det som framtida arbete.
109

Effects of a Bell-Shaped Lift Distribution on an Oblique Flying Wing and its Impact on Aerodynamic Performance

Deslich, Joshua 22 June 2020 (has links)
No description available.
110

The regional test of relationship between economic growth and CO2 emissions : --Evidence from Chinese provinces

Mo, Thoth, Wang, Weibin January 2023 (has links)
This thesis has investigated the validity of the Environmental Kuznets Curve in the provinces of China which assumes the increase in GDP per capita (income per capita) would generate the raise of CO2 emissions (pollution) until a turning point in which CO2 emissions start decreasing. The study includes 30 provinces over a period spanning from 2000 to 2019 by applying OLS and Fixed-effects regression model with panel data. The findings demonstrate that the provinces of China conform to the EKC theory's projections by exhibiting an inverted-U shape. Apart from that, this study also confirmed the presence of differences in turning points between provinces with high income and those with low income, and the former exhibiting a significantly higher value. Our research findings suggest that policymakers should tailor their CO2 emission reduction policies to the specific circumstances of each region. In the absence of appropriate measures, a negative outcome may arise.

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