Dissertations / Theses on the topic 'Light towers'
To see the other types of publications on this topic, follow the link: Light towers.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Light towers.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Thörn, Frida, and Wilhelm Sjöstedt. "Estimating the Risk of Self-Initiated Upward Lightning to Onshore Wind Turbines and Towers." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-295598.
Full textAbstract:
Field observations has shown that wind turbinesare especially exposed to lightning strikes. The probability forlightning strikes to offshore wind turbines has been analysed ina previous article. In this project the probability for upwardself-initiated lightning strikes to onshore wind turbines anda lightning protection tower was analysed. This was done bycollecting elevation data and recreating the site topographyin COMSOL Mutliphysics 5.5, and also by collecting weatherdata which were analysed in MATLAB. The probability for thecritical electrostatic field was then calculated and analysed. Theresult shows that the risk of lightning strike is correlated to thetopography and cloud height.Fältobservationer har visat att vindkraftverk är särskilt utsatta för blixtar. En tidigare studie har analyserat sannolikheten för blixtar på vindkraftverk belägna ute till havs. I det här projektet analyserades sannolikheten för blixtar på vindkraftverk och en vädermast på land. Detta gjordes genom att samla väder och topografidata från de undersökta områdena, som sedan modellerades i COMSOL Multiphysics 5.5. Sannolikheten att ett kritiskt elektriskt fält uppstår beräknades med hjälp av MATLAB. Resultatet visar att risken för blixtar är korrelerat med topografin och molnhöjden.
Kandidatexjobb i elektroteknik 2020, KTH, Stockholm
2
Dai, Jiaqi. "Opening and Space: A contemplative tower in the woods." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/92697.
Full textAbstract:
This thesis aims to explore architectural experience by addressing how different types of openings exert an impact to the space. The openings not only play a critical role in giving a palpable presence to natural light in a space, but also facilitate a specific way of seeing the world – together generating a spiritual resonance through a sequence of well-designed spaces.
The journey happens in a four-story tower, which is influenced by four parts of a tree, providing a space to experience tranquility removed from a chaotic world and to gain a deeper understanding of the trees. With an emphasis on the manipulation of natural light and views, certain kinds of atmospheres are created on each floor to shape the perception of space.Master of Architecture
3
Reader, Paul. "Towards light switchable surfaces." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17959.
Full textAbstract:
Thesis (MSc)--Stellenbosch University, 2011.ENGLISH ABSTRACT: Polymeric nanofibrous membranes that act as surfaces offer two compelling properties; they have extremely large surface areas that can be modified and they can offer multiple reactive sites depending on which polymer they were electrospun from. Combining nanofibrous surfaces such as these with photochromic dyes can give remarkable, light responsive materials. In this study, a terpolymer was electrospun and crosslinked (to impart insolubility to the material) to produce a nanofibrous mat that contained surface secondary-hydroxyl units and benzyl chloride units, from which monomers could grow using surface-initiated atom transfer polymerization (SI-ATRP). The surface was further fluorinated though the secondary-hydroxyl moieties to produce a hydrophobic crosslinked nanofibrous surface. n-Butyl acrylate and a photochromic spiropyran dye were copolymerized from the surface using SIATRP, in order to produce a surface that exhibited reversible adhesion towards a water droplet using ultraviolet and visible light as a stimulus to change between the two states. This in principle would allow the droplet to roll off and stick to the surface respectively. Although the surface displayed a colour change when switched, proving that the SI-ATRP had taken place, the droplet of water remained attached to the surface in both states.
AFRIKAANSE OPSOMMING: Polimeriese nanovesel membrane wat dien as oppervlaktes bied twee aantreklike eienskappe; hulle het baie groot oppervlakareas wat gemodifiseer kan word en hulle bied veelvuldige reaktiewe punte, afhangende van die polimeer waarvan hulle ge-elektrospin is. Deur sulke nanovesel oppervlaktes met fotochromiese kleurstowwe te kombineer, kan uitstekende lig reagerende materiale verkry word. In hierdie studie is ‘n terpolimeer ge-elektrospin en daarna gekruisbind (om die materiaal onoplosbaar te maak) om ‘n nanovesel web te kry wat oppervlak sekondêre-hidroksiel en benzielchloried eenhede bevat. Monomere kan dan vanaf hierdie eenhede groei deur middel van oppervlak-geïnisieerde atoomoordrag polimerisasie (OI-AOPR). Die oppervlak was verder gefluorineer via die sekondêre-hidroksiel eenhede om ‘n hidrofobiese, gekruisbinde nanovesel oppervlak te vorm. n-Butielakrilaat en ‘n fotochromiese spiropiraan kleurstof is gekopolimeriseer vanaf die oppervlak deur middel van OI-AORP om sodoende ‘n oppervlak te skep wat omkeerbare adhesie van ‘n water druppel gee as ultraviolet en sigbare lig as stimulus gebruik word om tussen die twee toestande te wissel. In beginsel sal die water druppel vanaf die oppervlak kan afrol én daaraan vassit, afhangende van die toestand van die oppervlak. Alhoewel die oppervlak van kleur verander het met die wisseling tussen die twee toestande, wat as bewys dien dat OI-AORP wel plaasgevind het, het die druppel water bly vassit aan die oppervlak in beide toestande.
4
Martin, Gregory Isaac. "Legitimizing the Senses and Provoking Emotions." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/33309.
Full text
5
Evans, Megan, and not supplied. "Towards a poetics of light: the conceits of light." RMIT University. Architecture and Design, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070418.095100.
Full textAbstract:
Towards a Poetics of Light; The Conceits of Light is a critical quest to map associations between rhetorical figures, psychological defences and spatial tropes in an attempt to conceive a poetic design that enacts conceit. Light is an emblem which echoes with an abundance of representations in literature, history, art and architecture and parallels may be drawn between their resemblances however apparently remote. Love, knowledge, hope and creative passion mark turns in the threads that knot ideas and their representations together. Return of the Immortals, the final project in a series of works exploring these parallels and representations, gathers together a cascade of tropes to structure a spatial experience which culminates in The Conceits of Light.
6
Mayeux, Annabelle. "Towards light-activated molecular devices." Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412647.
Full text
7
Graham, Katherine Joy. "Scenographic light : towards an understanding of expressive light in performance." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/20414/.
Full textAbstract:
In the expanded field of performance design research there is a growing understanding of the dynamic and affective capacities of performance materials, and how such materials may play a fundamental role in the audience experience of a given performance. Parallel to this research in scenography is a similar extension of the conception of the roles of light and dark in performance. Reconciling and extending these areas of research this PhD thesis posits the term ‘scenographic light’ to encapsulate the ability of performance light to actively inscribe dramaturgical meaning in space and time, arguing that light is capable of independently contributing to performance through its manipulation of space, time, and visuality. This doctoral research uses auto-ethnographic spectatorship as a means of identifying the unique contribution of light to performance. Employing a phenomenological framework to explore the dynamic role of light within performance, this study presents an ontology of light that is rooted in dramaturgical action. The experiential framework put forward in this research facilitates a theoretical discussion about the dramaturgical impact of light, revolving specifically around questions of how light affects other elements in performance, how it seems to perform as a material in itself, and how, in respect of these things, it can become a generative force in performance. By applying these questions to a wide range of contemporary performance practices I identify and articulate ways in which light can be considered a significant contributor to performance, working simultaneously with, but independently of, other elements in performance. The implications of this research invite an expanded view of the position of light in performance analysis, and suggest that the study of light may be productively aligned with explorations of audience engagement and affect.
8
Tsui, Jeffrey (Jeffrey Ling Siu) 1975. "Hyper-light architecture : composite tower for Hong Kong." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/70343.
Full textAbstract:
Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 2001.Includes bibliographical references (p. 94-102).
The initial concept of the thesis beg ins with an interest in understanding the materials, manufacturing and aesthetics of modern product design and its relation ship with architecture and space . The approach to the problem begins with an exploration of specific materials that are commonly used in other design and manufacturing fields but that are currently underutilized in the building construction industry. The thesis is an investigation of exploiting composite materials in developing a structural system for buildings and construction. Specific properties of composites, various connection . techniques as well as different construction/fabrication methods involved are essential issues that are explored throughout the design process. The project targets at creating a new typology and aesthetics in vertical building systems that takes advantage of the specific structural characteristics of these materials. Utilizing the characteristics of high -density site conditions such as the Central district in Hong Kong and through an application of a sensible programmatic organization, the project serves as a demonstration of the design within a realistic environment as well as within pragmatic constraints. The outline of the thesis is as follows: 1. Research and investigation of materials 2. Site analysis and background information, 3. Design requirements, criteria and decision-making 4. Models for experimentation and illustration of design ideas 5. Presentation materials
Jeffrey Tsui.
M.Arch.
9
Knotek, Michael P. "Adult faith growth through darkness, toward light /." Theological Research Exchange Network (TREN), 1988. http://www.tren.com.
Full text
10
Cailes, John. "Towards the light : A fictionalized (auto) biography." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2005. https://ro.ecu.edu.au/theses/673.
Full textAbstract:
Towards the Light - - at times biographical, autobiographical, and basically fiction - is built out of anecdotes supplied to me as the result of direct questioning of my parents and relatives, and from my own memories of past experiences; from private 'on the ground' observations both in Western Australia and in Cornwall, England – and, where factual information is lacking, a good deal of creative invention on my part. My paternal great-grandfather who at the age of eight began his working life in a Cornish tin mine provided me with a figure central to my purpose while constructing this narrative. To this character I have added details borrowed from or inspired by events that at times affected various other members of my family and those to whom they were devoted. Notable contributors to the composite character to whom I have given the name of Harry Coates, and to his family, are my father, his brothers and my own siblings. I suspect that I, too, appear reflected in the main text; but in general I have 'tried to contain my overt self within the autobiographical accompaniment that appears at the head of most chapters of the work. My over-arching interest, however, is in representing ordinary people such as inhabit the mostly anonymous majority of any society, the name-less ones whose existence is often only inferred in official histories; people such as the other forty-nine milliners and dressmakers besides Ann Haynes in Perth, for instance, to whom Tom Stannage refers in his The People of Perth (1979:114) or just a sample of the reported 8000 by which the Western Australian (white) population grew in the period 1870-1884 (Crowley,1964:33) - men and women who go about the vital business of their own survival.
11
Ahmed, Ibrahim Abdelhamid Soliman. "Vacuum Ultraviolet Light Irradiation towards Photochemical Surface Architectures." Kyoto University, 2017. http://hdl.handle.net/2433/227625.
Full text
12
Heffer, J. S. "Towards precision gravimetry using light-pulse atom interferometry." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3014202/.
Full textAbstract:
A light-pulse atom interferometer for inertial sensing applications such as gravimetry is being commissioned, where the prototype has a target relative precision (σ g /g) of one part per million to enable geophysics applications, which is three orders of magnitude less sensitive than commercial optical gravimeters, but with the potential to exceed these. As part of this, a rubidium-85 magneto-optical trap was upgraded using optical amplification and fibre optics to capture an atom population number of O(10 8 ) and sub-Doppler cooling techniques have been used to reach ultracold temperatures of 20 μK. Several interferometer subsystems have been developed, including extensive optical systems featuring a high-specification optical modulator and laser-induced fluorescence detection. Preliminary investigations into the coherent manipulation of atomic states have been implemented and the resonance peak of a stimulated Raman transition has been observed.
13
Kotru, Krish. "Toward a demonstration of a Light Force Accelerometer." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62486.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 79-81).
The Light Force Accelerometer (LFA) is an optical inertial sensor in which radiation pressure from two counter-propagating laser beams optically confines a glass microsphere. Inertial acceleration of the device results in microsphere displacement along the sensitive axis, which is subsequently nulled by optical forces to provide an acceleration measurement. A simple calculation that takes into account fundamental noise processes in the LFA (i.e., shot noise and RIN in the laser beams) places the sensitivity limit of this accelerometer at < 100 ng. By incorporating widely available, inexpensive optical components into a simple design, a high-precision LFA could provide an appealing alternative to other sensors of comparable performance. Previous work on the LFA revealed instabilities in proof mass position detection caused by the asphericity of microspheres. In this thesis, an alternative method for position detection which was less sensitive to shape-irregularities in microspheres was investigated. Results indicated that resolution of microsphere motion was enhanced significantly when the new detection method was implemented. This improvement. however, did not eliminate the position instabilities observed previously. Capabilities for optical trapping with two counter-propagating beams in air were also developed in this work. Trapping with feedback position control in air was demonstrated for the first time, but long-term trapping in vacuum was prohibitively difficult due to destabilizing mechanical vibrations. For a microsphere in atmospheric pressure, the estimated bias stability was 318 jig after 300 seconds of averaging, and the approximate short-term sensitivity was 500 pg/v/ Hz. Stabilization of mechanical vibrations and precise calibration of power measurements to acceleration will allow this two-beam trap to probe the performance limits of the LFA.
by Krish Kotru.
S.M.
14
Powell, Alexander. "Engineering plasmonic light scattering with thin dielectric films : towards enhanced light trapping and novel sensing elements." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:c18025ef-a693-441d-bd88-e37ebc09b6a5.
Full textAbstract:
Plasmonic research is becoming increasingly focused on the integration of noble metal nanostructures with planar devices to enhance their performance. Whilst the physics of noble metal nanoparticles at a simple interface is well studied, their behaviour inside a thin film structure is not. This work investigates the effect that placement in a thin dielectric film has on the excited modes and the directional scattering from various geometries of nanoparticle; the focus is on the fundamental principles but the application of this work in light trapping and nanoantenna design is also discussed. Research is conducted using finite-difference time-domain simulations and a custom built dark-field Fourier-space microscope, designed to interrogate individual particles and measure their angular scattering in thin films for the first time. It is found that the excited modes, large angle scattering and substrate coupling of the nanoparticles can be manipulated and improved considerably through careful choice of the materials and dimensions of the layers. Scattering from silver nanowires into a substrate is observed experimentally for the first time and an overcoating thin film is exploited to create highly directional emission, which is compared with nanoantennas in the literature. The potential to use this system as a novel sensing element is discussed. Following on from this, the nanocube patch antenna system is reviewed and its operation as a subwavelength plasmonic gas sensor is demonstrated for the first time to test for relative humidity using the Nafion polymer. This easily fabricable system shows superior sensitivities to other single-particle sensors across a range of humidities and simulations predict that by using sharper cubes and different deposition processes a further tripling of the recorded efficiency is achievable. The nanopatch structure can be readily adapted to detect a variety of other gases, and has the potential for integration into photonic circuitry.
15
Tomazou, Marios. "Towards light based dynamic control of synthetic biological systems." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/44243.
Full textAbstract:
For the field of synthetic biology, the adaptation of principles, from the well established traditional engineering disciplines, like mechanical and electrical engineering, in order to realise complex synthetic biological circuits, is an intriguing prospect. These principles can enable a forward engineering, rational design and implementation approach, where a system's properties can be predicted or designed in silico followed by the manufacturing of the in vivo system, that can be tested, used or redesigned in the most efficient possible way. Achieving control over these circuits, is one of the important topics of the field, for these applications to become robust and render useful functions applicable to energy, medicine, pharmaceuticals and agriculture industries. In this work, I attempt to explore light, as a promising control 'dial' for synthetic circuitry. Light is fast, economic compared to chemicals, it can be interfaced with electronics, it is reversible in its effect and can be applied at a fine spatio-temporal resolution. These characteristics, are absent from the classically used chemical inducers, meaning that light, can open new possibilities for the user to control synthetic systems, or even facilitate the cell to cell communication, within population based networks. This work, is a contribution towards harnessing the advantages of light, for achieving control over synthetic circuits. More specifically, I start with the detailed theoretical and experimental study of the Cph8 two component system, a synthetic chimeric receptor which is responsive to red light. This is done, in order to develop a sufficient theoretical understanding of it, through detailed mechanistic modelling, in order to connect the specific system with the toggle switch and the dual feedback oscillator, in an optimal way and achieve control of these devices through light. The developed model, was able to highlight the main aspects and mechanisms inherent to its structure, describe most of the observations from the experimental system, to also make quantitative predictions. The second part of this work, was the development of novel promoters, that can be regulated by a commonly used transcription factor, such as LacI, but also, light responsive regulators like OmpR and CcaR. This yielded a direct way to integrate light and chemical inputs, into a single output, while the dual regulation, allowed to connect and modulate the toggle switch without the need of additional transcription factors. The latter, a light tuneable toggle switch, showed indications that it can function as a memory controller that can be reset by light. Finally, I show the design and modelling of a light tuneable dual feedback oscillator, where light of one wavelength can be used to tune the amplitude, while another wavelength can tune the period. The developed models and synthetic circuits are expected to contribute towards implementing finely tuned and controlled synthetic circuits through light.
16
Xue, Jin Ph D. Massachusetts Institute of Technology. "Towards the efficiency limit of visible light-emitting diodes." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/108843.
Full textAbstract:
Thesis: S.M. in Electrical Engineering, Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 13-152).
In this thesis, a thermophotonic method based on the heat-pump mechanism is proposed to potentially enhance the efficiency of visible light-emitting diodes (LEDs) for high-power operation. By leveraging this special mode of solid-state lighting by incoherent electroluminescent radiation and with the focus on gallium-nitride (GaN) technologies, we experimentally demonstrate a thermally enhanced blue LED operating in the low bias regime, and theoretically investigate the characteristics and criteria for efficiency visible lighting based on a thermodynamic study.
by Jin Xue.
S.M. in Electrical Engineering
17
Morát, Julia. "Towards Stable Li-metal electrodefor rechargeable batteries." Thesis, Uppsala universitet, Strukturkemi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-306694.
Full textAbstract:
Different types of alumina containing coatings were made on lithiumand copper in the purpose to mechanically hinder the growth ofdendrites. Lithium, coated with polymer-alumina composites wereplaced in symmetric cells for in situ studies by a light microscope.The coatings did not block the dendrites, but they did change thegrowth rate and morphology of them, probably throw both chemicalinteractions and changes in ion transportation. Also the stability ofcapacity were tested for the same coatings, the result showed abigger capacity drop for cells containing coated lithium versus cellswithout coatings.Attempted alumina coatings were also made by a solgel technique, bydirect reaction with the compound trimethylaluminium and with analumina containing acetonitrile solution.The theses also includes a study of the stability of lithium inadiponitrile. A higher amount of LiTFSI salt in adiponitrile could bythis study be reported to inhibit the dissolution of lithium that wasseen for lower salt concentrations. The dissolution appeared when thesolution was used as an electrolyte in a symmetric lithium cell. Somedifferences could be seen when the lithium surface were studied byXPS after interaction with high, low and zero concentration LiTFSI.Both the XPS studies and the absences of lithium dissolutionindicates that a more or less stable SEI had been formed.
18
Romer-Jordan, Zachary L. "The Threshold of Experience: A Journey Toward Inward Reflection." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1275667134.
Full text
19
Dawson, Geoffrey E. "Toward a compact underwater structured light 3-D imaging system." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83705.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Department of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 53-54).
A compact underwater 3-D imaging system based on the principles of structured light was created for classroom demonstration and laboratory research purposes. The 3-D scanner design was based on research by the Hackengineer team at Rice University. The system is comprised of a low-power, open-source hardware single-board computer running a modified Linux distribution with OpenCV libraries, a DLP pico projector, camera board, and battery module with advanced power management. The system was designed to be low-cost, compact, and portable, while satisfying requirements for watertightness. Future development and applications may involve navigation systems for an autonomous underwater vehicle (AUV). An initial study of 3-D imaging methods is presented, and the strengths and drawbacks of each type are discussed. The structured light method was selected for further study for its ability to produce high-resolution 3-D images for a reasonable cost. The build of the 3-D imaging system was documented for reproducibility, and subsequent testing demonstrated its functions and ability to produce 3-D images. An instruction guide for operation of the device is provided for future classroom and laboratory use. The 3-D imaging system serves as a proof-of-concept for utilizing structured light methods to produce 3-D images underwater. Image resolution was limited by the output resolution of the pico projector and camera module. Further exploration in obtaining ultra high-resolution 3-D images may include use of a more powerful projector and a higher resolution camera board module with autofocus. Satisfactory 3-D scanning validated the performance of structured light scanning above water. However, contaminants in the water hindered accurate rendering by the system while submerged due to light scattering. Future development of a on-the-fly mapmaking system for AUV navigation should include algorithms for filtering light scattering, and hardware should based on an instantaneous structured light system utilizing the Kinect 2-D pattern method. Autofocus and increased projector brightness would also be worthwhile additions.
by Geoffrey E. Dawson.
S.B.
20
Alazemi, Talal Zaid A. "Kuwaiti foreign policy in light of the Iraqi invasion, with particular reference to Kuwait's policy towards Iraq, 1990-2010." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/13803.
Full textAbstract:
The study sheds light on the impact of the Iraq invasion of Kuwait in 1990 on Kuwaiti foreign policy, with particular reference to changes in behaviour towards Iraq, from 1990-2010, and the impact of this invasion on changes to the concepts of Kuwaiti foreign policy at regional, Arab and international levels. Thus, the study investigates the ‘impact’ of this invasion on Kuwaiti foreign behavior towards Iraq during the period from 1990 to 2010, the principles and determinants of Kuwaiti foreign policy towards Iraq in this period, and the ‘outstanding issues’ between Iraq and Kuwait and the Kuwaiti vision for Iraq after the fall of Saddam Hussein’s regime from 2003 until 2010. It finds that the trauma of the invasion drastically affected both Arab politics overall and Kuwait’s own policy: for the first time the notion of alliance became a cornerstone of Kuwait’s overall foreign policy – even if its geographical location and exposure to possible threats from Iraq meant that, after Saddam’s fall in 2003, there was a gradual evolution towards trying to help a stabilisation in that country occur. The combination of geographical location and ideational factors in the shape of sectarian cleavages crossing domestic and regional theatres, meant a continued sharp focus not only on military security with external help, but also on the pre-emption of spill-over effects from the sectarianised Iraqi political landscape to Kuwait’s own latent ethno-sectarian divisions. Even so, there were certain red lines that remained uncrossed, in the shape of the so-called outstanding issues that remained to be resolved between Iraq and Kuwait.
21
Richter, Laura. "A VLBI polarisation study of 43 GHZ SiO masers towards VY CMA /." Link to this resource, 2005. http://eprints.ru.ac.za/784/.
Full text
22
Richter, Laura. "A VLBI polarisation study of 43 GHZ SiO masers towards VY CMA." Thesis, Rhodes University, 2006. http://hdl.handle.net/10962/d1005284.
Full textAbstract:
This thesis reports the calibration, imaging and analysis of one epoch of VLBI observations of the v (italics) = J (italics) = 1-0 transition of SiO towards VY CMa. Full polarisation information was recorded, allowing high resolution synthesis maps of each of the four Stokes parameters to be produced. A total of 81 maser components were extracted from the total intensity map, each approximately 1 mas in size. The emission spans approximately 100 x 80 mas in right ascension and declination and is concentrated to the east. The maser component positions were fitted to a ring of radius ~ 3.2R₊ (italics), or 7.2 x 1O¹⁴ cm for a stellar distance of 1.5 kpc. If the stellar position is assumed to be the centre of this ring then almost all of the maser components fall within the inner dust shell radius, which is at ~ 5R (italics)ϰ All of the maser components fall between 1.5R (italics)ϰ and 6R (italics)ϰ. A velocity gradient with position angle was observed in the sparsely filled western region of the maser ring. If interpreted as evidence of shell rotation, this gradient implies a rotational velocity of v (italics) rot (subscirpt) sin i (italics) = 18 km.s⁻¹. The fractional circular and linear polarisations of the maser spots were derived from the Stokes parameter maps. The mean fractional circular polarisation of the masers components was ~ 2 percent and the median fractional linear polarisation was ~ 6 percent, with many spots displaying over ~ 30 percent linear polarisation. The mean circular polarisation implies a magnetic field of ~ 4 G in the SiO maser region if the polarisation is due to Zeeman splitting. Two maser components display a rotation of linear polarisation position angle with velocity, possibly implying a connection between the magnetic field and the velocity field variations in the region of these components.
23
Sivashankar, Pratulya. "Energy and recycling implications of transitions towards light-weight passenger cars." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for vann- og miljøteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19194.
Full textAbstract:
The overall approach to this thesis would be to start off by making a simple system (with the system boundaries) for steel and aluminium in an average car. The purpose of this would be to find out how one material can be used to substitute the other. The next step would involve looking into the historical stocks of steel and aluminium in cars and predict how they will be in the future. This will be done using dynamic MFA. It will be a global study of cars with a high focus on aluminium.The study will also look into the energy consumption and emissions (focusing on the climate change potential from cars). Historical and future emission scenarios will be made. Different scenarios for climate change mitigation will be tested, including light-weighting, a shift to electrical cars (Blue Map Scenario) and many other steel and aluminium related scenarios. The scenarios would be discussed and compared to results from LCA to show how the results are varying.
24
Haverinen, H. (Hanna). "Inkjet-printed quantum dot hybrid light-emitting devices—towards display applications." Doctoral thesis, University of Oulu, 2010. http://urn.fi/urn:isbn:9789514261275.
Full textAbstract:
Abstract
This thesis presents a novel method for fabricating quantum dot light-emitting devices (QDLEDs) based on colloidal inorganic light-emitting nanoparticles incorporated into an organic semiconductor matrix. CdSe core/ZnS shell nanoparticles were inkjet-printed in air and sandwiched between organic hole and electron transport layers to produce efficient photon-emissive media. The light-emitting devices fabricated here were tested as individual devices and integrated into a display setting, thus endorsing the capability of this method as a manufacturing approach for full-colour high-definition displays.
By choosing inkjet printing as a deposition method for quantum dots, several problems currently inevitable with alternative methods are addressed. First, inkjet printing promises simple patterning due to its drop-on-demand concept, thus overruling a need for complicated and laborious patterning methods. Secondly, manufacturing costs can be reduced significantly by introducing this prudent fabrication step for very expensive nanoparticles.
Since there are no prior demonstrations of inkjet printing of electroluminescent quantum dot devices in the literature, this work dives into the basics of inkjet printing of low-viscosity, relatively highly volatile quantum dot inks: piezo driver requirements, jetting parameters, fluid dynamics in the cartridge and on the surface, nanoparticle assembly in a wet droplet and packing of dots on the surface are main concerns in the experimental part. Device performance is likewise discussed and plays an important role in this thesis. Several compositional QDLED structures are described. In addition, different pixel geometries are discussed. The last part of this dissertation deals with the principles of QDLED displays and their basic components: RGB pixels and organic thin-film transistor (OTFT) drivers. Work related to transistors is intertwined with QDLED work; ideas for surface treatments that enhance nanoparticle packing are carried over from self-assembled monolayer (SAM) studies in the OTFT field. Moreover, all the work done in this thesis project was consolidated by one method, atomic force microscopy (AFM), which is discussed throughout the entire thesis.
25
王可欣 and Ho-yan Doris Wong. "Towards safe and environmentally sustainable public light bus servicesin Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31635672.
Full text
26
Horstmeyer, Roarke (Roarke William). "Towards a unified treatment of 3D display using partially coherent light." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/69525.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 111-120).
This thesis develops a novel method of decomposing a 3D phase space description of light into multiple partially coherent modes, and applies this decomposition to the creation of a more flexible 3D display format. Any type of light, whether it is completely coherent, partially coherent or incoherent, can be modeled either as a sum of coherent waves or as rays. A set of functions, known as phase space functions, provide an intuitive model for these waves or rays as they pass through a 3D volume to a display viewer's eyes. First, this thesis uses phase space functions to mathematically demonstrate the limitations of two popular 3D display setups: parallax barriers and coherent holograms. Second, this thesis develops a 3D image design algorithm based in phase space. The "mode-selection" algorithm can find an optimal holographic display setup to create any desired 3D image. It is based on an iterative algebraic-rank restriction process, and can be extended to model light with an arbitrary degree of partial coherence. Third, insights gained from partially coherent phase space representations lead to the suggestion of a new form of 3D display, implemented with multiple time-sequential diffracting screens. The mode-selection algorithm determines an optimal set of diffracting screens to display within the flicker-fusion rate of a viewer's eye. It is demonstrated both through simulation and experiment that this time-sequential display offers improved performance over a fixed holographic display, creating 3D images with increased intensity variation along depth. Finally, this thesis investigates the tradeoffs involved with multiplexing a holographic display over time with well-known strategies of multiplexing over space, illumination angle and wavelength. The examination of multiplexing tradeoffs is extended into the incoherent realm, where comparisons to ray-based 3D displays can hopefully offer a more unified summary of the limitations of controlling light within a volume.
by Roarke Horstmeyer.
S.M.
27
Bajpayee, Abhishek. "Towards real-time light field processing for quantitative imaging and perception." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119341.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 139-147).
This thesis aims to make light field imaging based 3D particle image velocimetry (PIV) practically feasible and affordable. In addition, this thesis also extends light field imaging techniques developed with PIV as a target application, for improved perception in robotics. Building upon the basic concepts of light field (LF) imaging which were developed as early as 1996, synthetic aperture (SA) PIV was demonstrated for the purpose of conducting accurate 3D PIV. However, when introduced, SAPIV had multiple limitations such as the need for 9 to 10 cameras as opposed 4 to 5 required by the popular tomographic PIV (Tomo-PIV) technique. In addition, SA reconstruction suffered from low reconstruction quality, slow computation speed and lack of robust and easy to use software. As a result, the adoption of SAPIV as a flow visualization technique was limited. Particle field reconstruction using LF or SA imaging succeeds by being able to systematically eliminate backscatter from illuminated particles in an experimental scene. A densely seeded PIV experiment can have a large amount of backscatter from particles in the volume of interest and a large synthetic aperture setup is capable of effectively seeing through this backscatter and accurately resolve features of interest at specific spatial coordinates. Work surrounding 3D PIV highlighted in this thesis improves the efficiency with which SA reconstruction eliminates out of focus particle backscatter thereby improving accuracy using less resources. These developments bridge the gap between SAPIV and other 3D PIV techniques. In addition, coupled with the homography fit method based SA reconstruction technique, presented results show that SAPIV, for the same experimental setup, is significantly faster and cheaper while achieving the same high level of accuracy. Developments of theoretical aspects of LF imaging for 3D PIV to improve visibility in scenes with large volume backscatter are fitting for applications in other areas as well. Mobile robots, especially autonomous cars, currently utilize multiple sensors such as cameras, LIDAR and RADAR for the purpose of localization and perception. However, visual sensing and autonomy in the face of edge cases and unexpected changes in scenes such as poor lighting, extreme weather conditions with heavy rain or snow etc. remains a challenge. We present a framework to facilitate the use of any multi-camera system as an array for LF capture along with a rendering methodology formulation that allows us to render LF images along arbitrary surfaces in scenes. In addition, by implementing our rendering technique to run on graphical processing units (GPUs), which have recently become affordable and easily available, we demonstrate the use of LF imaging for real-time perception for the first time. We envision that this framework can eventually help improve perception for robots by supplementing higher level algorithms.
by Abhishek Bajpayee.
Ph. D.
28
Lindh, Mattias. "Inkjet deposition of electrolyte : Towards Fully Printed Light-emitting Electrochemical Cells." Thesis, Umeå universitet, Institutionen för fysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-80272.
Full textAbstract:
Organic electronics is a hot and modern topic which holds great promise for present and future applications. One such application is the light-emitting electrochemical cell (LEC). It can be fully solution processed and driven at low voltage providing light emission from a large surface. Inkjet printers available today can print a variety of inks, both solutions and dispersions. The technique is scalable and a quick and easy way to accurately deposit small quantities of material in user definable patterns onto a substrate. This is desirable to make low cost and efficient optical devices like displays. In this thesis it has been shown that solid electrolytes, after being dissolved in a liquid solvent, can be inkjet printed into a set of well separated distinct drops with an average maximum thickness of 150 nm. The electrolytes are commonly used in LECs and comprised by poly(ethylene glycol) with molar masses ranging from 1 – 35 kg/mol, and potassium trifluoromethanesulfonate (KCF3 SO3 )—together dissolved incyclohexanone to form an ink. The smallest achieved edge to edge distance between the printed drops was 40 μm. Together with a drop diameter of 50 μm it yields a coverage of 24% at a resolution of 280 dpi. Profiles of dried deposited drops of electrolyte were examined with a profilometer, which showed adistinct coffee ring effect on each drop. In particular, the ridges of the coffee rings were broken into pillar like shapes, together forming a structure akin to a scandinavian ancient remnant called stone ship. Different drop diameters were measured in and between the indium tin oxide samples. The drops’ speeds and sizes atejection from the nozzles seemed unchanged, and wettability is most probably the physical phenomena tolook into in order to understand what generates the differences. Local changes in surface roughness and/or surface energy, possibly originating from the cleaning process of the samples, is most likely the cause. No indications towards large differences in surface tension between the printable inks were seen, however their viscoelastic properties were not measured. As part of the thesis work a LEC characterization set-up was built. It drives a LEC at constant currentand measures the driving voltage, -current, and luminance over time. The set-up is controlled by a Labview virtual instrument and the data exported to a text-file for later analysis. The precision of the luminance measurements is ±0.1 cd/m2 for readings < 50 cd/m2 , but the accuracy is uncertain. The conclusion of this thesis is that it is indeed possible to print solid electrolytes dissolved in cyclo-hexanone with an inkjet printer. However, in order to fully understand the spreading and drying of thedrops, studies of the inks’ viscoelastic properties, together with surface roughness and -energy density ofthe substrates, are needed. The largest molar mass of nicely printable poly(ethylene glycol), at an ink concentration of 10 mg/ml, was 35 kg/mol. This is comparable to the molar mass of an active light-emittingmaterial, “SuperYellow”, often used in LECs. Even though their respective molecular structures are very different, this indicates that inkjet printing of complete LEC-inks, containing both the active material and solid electrolyte, is feasible. Most probably it would require substantial tuning of the printing parameters. This thesis provides further hope for future fully inkjet printed LECs.
29
Torgersrud, Cody. "Light and Privacy, A proposal towards a testing and education standard." Thesis, KTH, Ljusdesign, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280040.
Full textAbstract:
The transformation of the architects’ vision to architectural form is a lengthy process. From initial sketch to day-to-day life, a design is transformed through the reality of occupation. No matter how much effort is put into a design its final effectiveness is determined by the end user. The access to ample daylight balanced with an adequate sense of visual privacy within ones one home is not often accounted for within the planning process. With current legislation making access to daylight a right within many developed countries, guaranteeing that access within the dense urban environment can mean putting resident’s privacy into question when planning to meet these daylight requirements. Failing to consider the privacy needs of all residents, especially immigrant groups, can lead to privacy driven modifications counterproductive to the overall goal of increasing access to daylight. Resident modifications can, in turn, lead to reductions of daylight levels within the home. There is a need for a system of analysis when it comes to the balance of access to daylight and adequate visual privacy, connecting the critical impacts of these factors on the human physiology and psychology. This proposal puts forward a system to analyze the relationship between the effective light transmission and the perceived visual privacy provided by a given visual privacy solution. The study is based off the analysis of current research regarding the effect of daylight on the human body, the importance of privacy within the home, the impact of cultural background on perception of privacy, and the impact of changing urban density on how people live. The research proposes a system of measurement taking into consideration both the quantitative effective daylight transmittance and a systematic qualitative analysis of perceived visual privacy through participant survey. The data collected would eventually be combined in a way that could be easily communicated to architects, designers, manufacturers and most importantly the end user. This system would be used to ensure that residents are able to effectively balance the level of privacy they require while mitigating the loss of daylight within their homes helping to insure the most benefits for the resident regardless of what home they find themselves in.
30
Burks, Sidney. "Towards a Quantum Memory for Nonclassical Light with Cold Atomic Ensembles." Paris 6, 2010. http://www.theses.fr/2010PA066380.
Full textAbstract:
Une mémoire quantique reversible permettant de stocker et relire de l'information quantique est une composante majeure dans la mise en oeuvre de nombreux protocoles d'information quantique. Comme la lumière est un porteur de l'information quantique fiable sur des longues distances, et comme les atomes offrent la possibilité d'obtenir de longues durées de stockage, le recherche actuelle sur la création d'une mémoire quantique se concentre sur la transfert des fluctuations quantiques de la lumière sur des cohérences atomiques. Le travail réalisé durant cette thèse porte sur le développement d'une mémoire quantique pour la lumière comprimée, utilisant un ensemble d'atomes froids de Cesium stockés dans un piège magnéto-optique. Nos deux principaux objectifs étaient le developpement d'une source de lumière non-classique, et le developpement d'un millieu atomique pour le stockage de celle-ci. Tout d'abord, nous commençons par présenter la construction d'un oscillateur paramétrique optique qui utilise un cristal nonlineaire de PPKTP. Cet OPO fonctionne comme source d'états de vide comprimé resonant avec la raie du Cesium. Nous caractérisons ces états grâce à une reconstruction par tomographie quantique, en utilisant une approche de vraisemblance maximale. Ensuite, nous examinons une nouvelle expérience qui nous permet d'utiliser comme millieu de stockage des atomes froids de Césium dans un piège magneto-optique récemment dévéloppé. Car cette expérience exige l'utilisation de nouveaux outils et techniques, nous discutons le developpement de ceux-ci, et comment ils ont contribué à notre progression vers le stockage des états quantiques dans nos atomes des Cesium, et finalement vers l'intrication de deux ensembles atomiques.
31
Dean, Ryan. "Towards visible light switching of peptide-DNA and peptide-protein interactions." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/111805/.
Full textAbstract:
Peptides derived from DNA-binding zinc finger proteins were synthesised with pairs of cysteine residues with i,i+7 and i,i+11 relative spacings introduced into their sequence. The sidechains of these cysteine residues were then alkylated with the well-known water soluble photochrome 3,3’-bis(sulfo)-4,4’-bis(chloroacetamino) azobenzene (BSBCA). The change of shape of the azobenzene dye in these peptide-dye conjugates allowed photocontrol of peptide structure and thus peptide-DNA interactions. For a single zinc finger helix, UV irradiation yielded a peptide conjugate with a dissociation constant with respect to its cognate DNA sequence of 100 nM with no binding apparent prior to irradiation. However, the relatively short half-life of BSBCA proved a stumbling block, particularly in the control of larger peptides using multiple azobenzenes to control several -helical structural elements within large peptides. In addition to the short half-life of cis-BSBCA under physiological conditions, multiple BSBCA switches attached to the same peptide were shown not to relax independently of each other. These results led to the design, synthesis and examination of novel photo switches sensitive to visible, rather than UV light, with improved light state half-lives and bidirectional optical switching. Initial studies on thioindigo-based switches proved that molecules sufficiently polar to be water soluble were inaccessible by concise synthetic routes. Attention was then turned to the synthesis of ortho-halogen substituted azobenzenes and investigation of several new conjugation strategies for linking these photosensitive molecules to peptides. Subsequent refinements to the design of the tetra-ortho-halogen substituted azobenzenes altered the position of UV/visible absorbance bands of the cis and trans isomers to create a 47 nm separation in the wavelengths of the n-π* absorbances of the isomers to allow effective bidirectional switching. These changes also improved the half-life of the cis state from 24 minutes at 20 0C to 3,256 minutes at 60 0C. One of these new azobenzenes was reacted with apoptosis-inducing Bak peptides with different cysteine spacings (i,i+7 and i,i+11). Less stringent control over the binding of these peptides to Bcl-xL was observed than with BSBCA, perhaps due to the more flexible nature of the new crosslinker, but the optical properties of this class of molecules suggest a little further development will yield much improved photoswitches.
32
Ammons, Stephen Mark. "Towards advanced study of Active Galactic Nuclei with visible light adaptive optics /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2009. http://uclibs.org/PID/11984.
Full text
33
Wong, Ho-yan Doris. "Towards safe and environmentally sustainable public light bus services in Hong Kong." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B31635672.
Full text
34
Burks, Sidney. "Towards A Quantum Memory For Non-Classical Light With Cold Atomic Ensembles." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00699270.
Full textAbstract:
Une mémoire quantique réversible permettant de stocker et relire de l'information quantique est une composante majeure dans la mise en œuvre de nombreux protocoles d'information quantique. Comme la lumière est un porteur de l'information quantique fiable sur des longues distances, et comme les atomes offrent la possibilité d'obtenir de longues durées de stockage, le recherche actuelle sur la création d'une mémoire quantique se concentre sur la transfert des fluctuations quantiques de la lumière sur des cohérences atomiques. Le travail réalisé durant cette thèse porte sur le développement d'une mémoire quantique pour la lumière comprimée, utilisant un ensemble d'atomes froids de Césium stock'es dans un piege magnéto-optique. Nos deux principaux objectifs étaient le développement d'une source de lumière non-classique, et le développement d'un milieu atomique pour le stockage de celle-ci. Tout d'abord, nous commençons par présenter la construction d'un oscillateur paramétrique optique qui utilise un cristal non-linéaire de PPKTP. Cet OPO fonctionne comme source d'états de vide comprime résonant avec la raie D2 du Césium. Nous caractérisons ces états grâce à une reconstruction par tomographie quantique, en utilisant une approche de vraisemblance maximale. Ensuite, nous examinons une nouvelle expérience qui nous permet d'utiliser comme milieu de stockage des atomes froids de Césium dans un piège magneto-optique récemment développé. Car cette expérience exige l'utilisation de nouveaux outils et techniques, nous discutons le développement de ceux-ci, et comment ils ont contribue à notre progression vers le stockage des états quantiques dans nos atomes des Césium, et finalement vers l'intrication de deux ensembles atomiques.
35
Rajabali, Anar. "(Re)turning to the poetic I/eye : towards a literacy of light." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61048.
Full textAbstract:
Rumi once wrote: “When I stop speaking, this poem will close and open its silent wings” (as cited in Barks, 1999, p. 66). This arts-based dissertation is a personal, poetic, and pedagogical study into the kinship between poetic discourse and spiritual expression where I attend to the question: what does it mean to dwell poetically? (Heidegger, 1971; Hölderin, 1984). I contextualize poetry as “the articulation of contemplative perception” (Laude, 2004, p. 11), “a phenomenology of the soul” (Bachelard, 1964, p. xxi), wherein poetic knowledge is a theoria (Lakhani, 2010). I refer to theoria as a way of intellectual seeing that recognizes the sacred in the mundane, which becomes central to my own poetic vision. In enacting this (re)search where writing is the inquiry (Richardson, 2000), I use phenomenologically informed perspectives of a/r/tography in qualitative research that “seeks to show and evoke the presence of a lived experience” (Todres, 2007, p. xi), where theorizing through the inquiry process brings forth understandings (Irwin & Springgay, 2008). In this meta work of researching poetry through poetry, I consider each poetic turn a mediation and meditation in “living a life of deep meaning through perceptual practices that reveal what was once hidden” (Irwin, as cited in Pinar, 2004, p. 10). In a research endeavour that is revelatory, this research site becomes insight. I draw upon Deleuze and Guattari’s (1987) metaphor of the rhizome, the underground root system of plants and theoretical underpinning of a/r/tography, which I reconceptualise in the sky to represent my dissertation as writing into a poetics of light. In visualizing what I imagine as a “sky of inquiry,” I make a call for research that has a “wider epistemological embrace” (Todres, 2007, p. 180) in the poetic gaze changing how, what and whom we see (Leggo, 2004a; Cheetham, 2012). Through lyrical ways, each layer of my inquiry sheds light towards understanding poetry as a contemplative pedagogy. In (re)turning to the poetic I/eye, this research represents a pledge to pedagogical encounters that nurture spiritual literacy where purposeful engagement in creative practices can become a gateway to the realms of spirituality. Supplementary audio material is available at: http://hdl.handle.net/2429/61130Education, Faculty of
Language and Literacy Education (LLED), Department of
Graduate
36
Evans, Reed, Ricardo García Guerra, Myriam Schaefer, and Isabella Wagner. "The Green Light towards Sustainability : Embedding Sustainability into a Branded Design Company." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2398.
Full textAbstract:
Production and consumption of products contribute to the global sustainability challenge by degrading natural and social systems. This thesis focuses on branded products, which through powerful images and meanings symbolise the core business of a company and a platform of identification for its stakeholders. This study investigates the possibility to align a brand and its company with sustainability. With the help of a small branded design company in Berlin, which served as case study, a strategic management planning process was conducted and action research was used to be able to engage the participants in creating movement towards sustainability. The research shows that there are major internal and external barriers and motivations that can either hinder or inspire. The actions and approaches that were identified for a branded design company represent possible means to transform its business towards sustainability. Natural resources are decreasing relative to the growth in human population and affluence. This fuels the need to develop more sustainable products so that human needs and natural eco-systems can thrive. A branded design company has the ability to help lead society through innovating products, services, and activities towards a sustainable future.
37
Nalbantoglu, Tugrul. "Towards a hydrogen bond mediated directional walker and light driven molecular shuttles." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/towards-a-hydrogen-bond-mediated-directional-walker-and-light-driven-molecular-shuttles(fb210b38-4079-4376-942e-b907a8f82d3f).html.
Full textAbstract:
This thesis reports the efforts towards the design and synthesis of a small molecule walker that would potentially move along the track directionally by exploiting the secondary interactions between the track and the walker. This thesis also reports the synthesis and operation of a light driven molecular shuttle featuring a novel acylpyridyl hydrazone station. Chapter One describes the biological walkers which are the source of inspiration towards the synthetic walkers, characteristics of a walker, previously described small molecule walkers and recent progress on the synthesis of molecular shuttles that operate under variety of different stimuli. Chapter Two describes the design and synthetic efforts towards a molecular walker that has the potential to operate directionally along the track by exploiting secondary interactions between the walker and the track namely the hydrogen bonding interactions introduced by subtle incorporation of excellent hydrogen bond donor/acceptor squaramides. This chapter briefly mentions the hydrogen bonding capabilities of squaramides on which the directional operation relies. Optimization of critical reactions and attempted strategies for the assembly of the whole machine is described as well. Chapter Three describes the synthesis and operation of 1- and 2- station [2]-rotaxanes that operate under light irradiation. 2- station [2]-rotaxane that function as a light driven molecular shuttle presents remarkable positional fidelity with high efficacy. The bistable acyl pyridyl station is incorporated as a photo active station upon which light irradiation alters the binding affinities towards the macrocycle. Series of rotaxanes featuring different amide based stations were synthesized to determine the best non-photo active station.
38
Roques-Carmes, Charles. "Towards broadly-tunable CMOS-compatible silicon light sources in the near-infrared." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118049.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 47-52).
The efficient extraction of light from silicon is one of the longstanding challenges of modem engineering and physics. The difficulty mainly arises from silicon's indirect bandgap and the short lifetime of non-radiative processes such as Auger recombination. Nonetheless, the realization of an energy efficient silicon-based photon source could find broad applicability in areas such as ultra-large scale integration (ULSI), optoelectronic displays and lighting. Every practical solution proposed thus far to this fundamental, yet technologically critical problem, relies on the physical patterning or chemical modification of silicon substrates, most of these transformations requiring high annealing temperatures or fabrication steps that are not compatible with conventional ULSI processes. In this thesis, we experimentally demonstrate the generation of tunable radiation in the near-infrared (800 to 1600 nm) from a simple periodic silicon grating. The light emission is generated by spontaneous emission from these gratings interacting with low-energy free electrons (as low as 2 keV) and is recorded in the silicon transparency window. We develop time-domain numerics that confirms our experimental results and our evaluation of the output radiation power. In addition, we theoretically investigate the feasibility of an allsilicon compact tunable radiation source at telecommunication wavelengths comprised of a silicon Field Emitter Array (FEA) integrated with a silicon periodic structure. Our results pave the way towards the realization of a CMOS-compatible electrically-pumped silicon light source.
by Charles Roques-Carmes.
S.M.
39
Mc, Galey William. "Changing Attitudes Towards Immigrants in Light of Worsening Economic Conditions in Portugal." Thesis, Stockholms universitet, Sociologiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-128461.
Full textAbstract:
Portugal has experienced various structural changes in recent history which have greatly contributed to the country having a sizeable and varied immigrant population at present. The Global Economic Crisis of 2008 has severely impacted numerous countries in the European Union including Portugal. Conditions in Portugal had been gradually worsening, largely as a result of a stagnating national economy, where unemployment steadily increased in the years leading up to 2008. In the wake of the crisis, Portugal has experienced dramatic reductions in GDP, soaring unemployment rates and in particular regarding youth unemployment, social unrest and political instability. Further, the most vulnerable socioeconomic groups in Portugal have been worst affected, where social inequality, poverty and a whole array of other social issues have been exacerbated by the crisis and the austerity policies that were implemented in the wake of the economic crash. This thesis attempted to discover if attitudes towards immigrants have changed in light of worsening economic conditions in Portugal during three different time periods 2002-2006-2012, with a primary focus on the most recent period where conditions were most austere. Moreover, this research also sought to establish the determinants which influence attitudes towards immigrants over the same time period. Data was used from three rounds of the European Social Survey and in particular, round 1 (2002/2003), round 3 (2006/2007) and round 6 (2012/2013). Descriptive statistics and ordered logistic regressions were used in order to answer the research questions and realistic group conflict theory was utilised as a theoretical framework when analysing and explaining the findings. It was evident that attitudes towards immigrants have become more negative over the given time period and were indeed most pronounced in light of the recent economic crisis. It was also apparent that natives who were in greater competition with immigrants possessed the most pronounced levels of prejudice.
40
Peers, Martyn. "Ruthenium(II) and iridium(III) complexes as photosensitisers towards light-driven biocatalysis." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/rutheniumii-and-iridiumiii-complexes-as-photosensitisers-towards-lightdriven-biocatalysis(ad591d9d-298c-4eca-9ccd-88df626c9fa8).html.
Full textAbstract:
Biocatalysis is becoming an increasingly attractive alternative to more traditional chemical transformations for use in pharmaceutical and industrial applications. This interest is primarily a consequence of the high regio-, stereo- and enantioselectivity that is associated with enzyme catalysed reactions. However, the proliferation of such techniques has been limited due to the dependence of enzyme activity upon the presence of redox cofactors, which are typically expensive and must be used in conjunction with efficient regeneration systems. Whilst numerous methods have been described, of particular potential are those that employ exogenous photosensitisers as a means of generating reducing equivalents to promote catalytic turnover. In this study the potential of transition metal complexes as photosensitisers towards the development of light-driven biocatalytic systems is evaluated. Use of such compounds gives great scope towards fine-tuning the spectral and redox properties of the sensitisers with the aim of optimising catalytic efficiency. Detailed herein is an extensive study towards the synthesis and characterisation of a range of ruthenium(II) and iridium(III) coordination compounds. Using NMR, UV-vis, and electrochemical techniques, all complexes were fully characterised and the origins of the photophysical properties further investigated using time-dependent density functional theory (TD-DFT) calculations. A series of ruthenium compounds were synthesised containing the bis(2,2′-bipyrazyl)ruthenium(II) moiety, investigating the impact of changes made to the functionality of the ancillary ligand upon the overall properties of the complex. New synthetic procedures have been developed towards the preparation of both 2,2′-bipyrazine and the related complexes, exhibiting significant benefits over previously established methods. Through manipulating the electron density of the ancillary ligand it is shown that the redox properties may be effectively tuned upon inducing changes in the energy of the metal-based HOMO. The utilisation of cyclometalated iridium(III) complexes in aqueous systems has been limited due to a poor water solubility that is typically associated with these compounds. Herein it is demonstrated that this issue may be effectively circumvented on inclusion of the positively charged pyridinium moiety. Upon incorporation of this functional group into either the cyclometalating or ancillary ligands, two distinct series of compounds were successfully prepared. Complexes of the substituted quaterpyridinium ligands possess complicated UV-vis spectra that exhibit low intensity absorbance up to 650 nm. A number of monoquaternised bipyridinium compounds were also utilised as pyridine derived N-heterocyclic carbene cyclometalating ligands, to afford a range of complexes with unique redox properties. The prepared photosensitisers were subsequently used to induce catalytic turnover in light-driven biocatalytic systems utilising the flavin dependent oxidoreductase enzymes, pentaerythritol tetranitrate reductase (PETNR) and the thermophilic old yellow enzyme (TOYE). Through an extensive investigation, optimal reaction conditions have been identified and a mechanism of electron transfer proposed. These systems were successfully implemented in the reduction of a broad range of substrates under both aqueous and biphasic conditions, delivering yields and enantiomeric excesses comparable to those obtained utilising an enzyme coupled regeneration system. This study clearly demonstrates that transition metal complexes are excellent candidates in developing practical light-driven biocatalytic systems. It is expected that, with further investigation, this approach can be readily expanded to incorporate a variety of applications and provide an effective alternative to the use of costly redox cofactors and a reliance upon complex regeneration techniques.
41
Chaigne, Thomas. "Control of scattered coherent light and photoacoustic imaging : toward light focusing in deep tissue and enhanced, sub-acoustic resolution photoacoustic imaging." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066162/document.
Full textAbstract:
En microscopie, savoir focaliser la lumière à l’échelle micrométrique est déterminant. Dans les tissus biologiques néanmoins, les inhomogénéités du milieu diffusent la lumière, empêchant toute focalisation au-delà d’une profondeur de l’ordre du millimètre. Des techniques de façonnage de front d’onde ont été développées afin de pré-compenser la distorsion du faisceau lumineux induite par la propagation à travers un milieu diffusant. Pour parvenir à focaliser la lumière à l’intérieur même du milieu diffusant, l’enjeu est de mesurer l’intensité lumineuse en profondeur de manière non invasive. Nous proposons d’utiliser l’effet photoacoustique pour sonder cette intensité. Une structure optiquement absorbante éclairée par une impulsion lumineuse émet en effet un signal ultrasonore, dont l’amplitude est proportionnelle à l’intensité lumineuse. Ces ultrasons se propagent de façon quasi-balistique dans les tissus mous et peuvent donc être détectés à l’aide d’un transducteur acoustique externe. Cette mesure permet donc de déterminer l’intensité lumineuse éclairant l’absorbeur. Nous avons montré qu’il était possible d’utiliser l'imagerie photoacoustique pour mesurer la matrice de transmission d’un échantillon diffusant. Cette caractérisation nous permet de focaliser la lumière sur des structures absorbantes et de sonder des propriétés mésoscopiques du milieu diffusant. Nous avons montré que la large bande spectrale des signaux photoacoustiques permet d’améliorer la focalisation. Enfin, nous avons montré que l’utilisation d’une source de lumière cohérente permet de pallier certains artefacts de l’imagerie photoacoustique, ainsi que de franchir la limite de résolution acoustiqueLight focusing is a crucial requirement for high resolution optical imaging. In biological tissue though, refractive index inhomogeneities scatter light, preventing any focusing beyond one millimeter. Wavefront shaping techniques have been recently developed to partially compensate for light scattering after propagation through a scattering medium. These techniques require a measurement of the light intensity at the target point. These techniques hold much promise for performing wavefront correction in order to focus light deep inside scattering media. This would require a non-invasive measure of the light intensity at depth. In this PhD study, we propose to use the photoacoustic effect for such task. An optically absorbing structure under pulsed illumination indeed generates ultrasonic waves, whose amplitude is proportional to the absorbed light intensity. These ultrasounds mostly propagate in a ballistic way, and can therefore be detected with an external transducer. We have shown that photoacoustic imaging could be used to measure the transmission matrix of a scattering sample, enabling to focus light on absorbing structures as well as to retrieve mesoscopic properties of the medium. We have shown that the broadband spectral content of the photoacoustic signals can be harnessed to improve the focusing performances. Finally, we demonstrated that coherent illumination could be used to remove fundamentals artefacts, as well as to break the acoustic resolution limit of conventional deep tissue photoacoustic imaging
42
Taylor, Jonathan Lorin. "Lines of Discovery." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/35461.
Full textAbstract:
An entry for the World Trade Center Memorial Competition was expanded upon as a study into the nature of design. The project influenced its own evolution and revealed exciting outcomes. The memorial is a reinforced concrete tower with an acrylic water tank at the top. The water tank acts as a prism casting colorful light displays both in the tower and around the site. The tank is also the source for continually falling droplets of water. The drops fall 450 feet through an open chamber to land in a shallow overflowing pool and then wash over a stone sepulcher containing the unidentified remains of victims.Master of Architecture
43
Claros, Casielles Miguel. "Development of Visible Light Photoredox Methodologies towards the Activation of Carbon-Halogen Bonds." Doctoral thesis, Universitat Rovira i Virgili, 2020. http://hdl.handle.net/10803/669435.
Full textAbstract:
Metodologies fotocatalítiques sota irradiació de llum visible han estat desenvolupades amb diversos substrats disponibles al mercat com ara els àcids carboxílics, trifluoroboratos alquílics de potassi, silicats alquílics d'amoni o èsters activats entre d'altres. Sota irradiació de llum, aquests precursors s'activen mitjançant processos de transferència d'un sol electró amb catalitzadors fotoexcitables (PC). Entre ells, els halurs orgànics són socis d'acoblament convenients en la fotocatàlisi, ja que experimenten una escissió de l'enllaç C-halogen catalitzada per diversos PC en presència d'un donador d'electrons. Els clorurs de llogo no activats, que són fàcilment disponibles i matèries primeres estables, exhibeixen una inèrcia química inherent, en part, per les seves negatius potencials de reducció. Això va impedir el seu ús generalitzat com a precursors radicals en la fotocatàlisi de llum visible. En aquesta dissertació doctoral explorem l'ús d'un sistema catalític dual basat en metalls de la primera sèrie de transició (Cu, Co, Ni) per a l'activació d'aquests enllaços inerts C-Halogen. El disseny de l'catalitzador ha estat clau per desenvolupar una metodologia suau i general per a la reacció de desalogenación i la ciclació reductora intramolecular d'halurs d'alquil no activats amb alquens o alquins units. L'escissió de fortes enllaços Csp3-X està intervinguda per un intermedi de cobalt o níquel en baix estat d'oxidació altament nucleòfil generat per reducció fotocatalítica de llum visible que empra un fotosensibilitzador de coure.Metodologías fotocatalíticas bajo irradiación de luz visible han sido desarrolladas con varios sustratos disponibles en el mercado como por ejemplo los ácidos carboxílicos, trifluoroboratos alquílicos de potasio, silicatos alquílicos de amonio o ésteres activados entre otros. Bajo irradiación de luz, estos precursores se activan mediante procesos de transferencia de un solo electrón con catalizadores fotoexcitables (PC). Entre ellos, los haluros orgánicos son socios de acoplamiento convenientes en la fotocatálisis, ya que experimentan una escisión del enlace C-halógeno catalizada por varios PC en presencia de un dador de electrones. Los cloruros de alquilo no activados, que son fácilmente disponibles y materias primas estables, exhiben una inercia química inherente, en parte, debido a sus negativos potenciales de reducción. Esto impidió su uso generalizado como precursores radicales en la fotocatálisis de luz visible. En esta disertación doctoral exploramos el uso de un sistema catalítico dual basado en metales de la primera serie de transición (Cu, Co, Ni) para la activación de estos enlaces inertes C-Halógeno. El diseño del catalizador ha sido clave para desarrollar una metodología suave y general para la reacción de deshalogenación y la ciclación reductora intramolecular de haluros de alquilo no activados con alquenos o alquinos unidos. La escisión de fuertes enlaces Csp3-X está mediada por un intermedio de cobalto o níquel en bajo estado de oxidación altamente nucleófilo generado por reducción fotocatalítica de luz visible que emplea un fotosensibilizador de cobre.
Visible light photoredox Catalysis have been accomplished with several readily available bench-stable chemicals such as carboxylic acids, potassium alkyltrifluoroborates, ammonium alkyl silicates or redox-active esters among others. Under light irradiation, these precursors get activated by single-electron transfer processes with photoexcitable catalysts (PCs). Among them, organic halides are convenient coupling partners in photocatalysis since they undergo reductive C-halogen bond cleavage catalysed by several PCs in the presence of a sacrificial electron-donor. Non-activated alkyl chlorides, which are readily available and bench-stable feedstocks, exhibit an inherent chemical inertness, in part, due to their large negative reduction potentials. This precluded their widespread use as radical precursors in visible-light photocatalysis. In this doctoral dissertation we explored the use of a dual catalyst system based on first-row transition metals (Cu, Co, Ni) for the activation of these inert Carbon-Halogen bonds. Catalyst design has been key for developing a mild and general photoredox methodology for the dehydrodehalogenation reaction and the intramolecular reductive cyclization of non-activated alkyl halides with tethered alkenes or alkynes. The cleavage of strong Csp3-X bonds is mediated by a highly nucleophilic low-valent cobalt or nickel intermediate generated by visible-light photoredox reduction employing a copper photosensitizer
44
Gu, Gong. "Stacked organic light emitting devices an approach toward full color flat panel displays /." Click to view the dissertation via Digital dissertation consortium, 1999.
Find full text
45
Tellez, Limon Ricardo. "Light propagation in integrated chains of metallic nanowires : towards a nano-sensing device." Thesis, Troyes, 2014. http://www.theses.fr/2014TROY0039/document.
Full textAbstract:
Les systèmes optiques intégrés ont été largement utilisés dans la détection et la caractérisation de substances biochimiques. Aussi, le développement de nouvelles technologies permettant la fabrication de structures intégrées à l’échelle nanométrique, ouvre un horizon dans la conception d'une nouvelle génération de capteurs biochimiques. Sur la base de plasmons de surface localisés, au cours des dernières années ont été proposés différentes configurations de systèmes optiques pour concentrer le champ électromagnétique dans une petite région de l'espace, ce qui favorise son interaction avec des substances biochimiques. En utilisant la méthode modale de Fourier, dans la présent thèse est présentée une analyse exhaustive de la propagation des modes dans un réseau périodique de nanoparticules métalliques intégrés avec une guide d'ondes diélectrique. Deux géométries des nanoparticules ont été étudiées: des réseaux périodiques de nanofils et de nanocônes métalliques. Il est démontré que pour les nanocônes métalliques le champ optique est fortement exalté au sommet des nanocônes quand ils sont excités à leur résonance LSP via une guide d'onde diélectrique. Pour valider les résultats numériques, on a fabriqué et caractérisé expérimentalement un réseau périodique de nanofils d’or placée sur une guide d’onde à échange d’ions. La caractérisation de l'échantillon a été réalisée dans le champ lointain en mesurant des spectres de transmission et dans le champ proche en utilisant la microscopie en champ proche optique de balayage (NSOM). Les résultats obtenus montrent que les dispositifs intégrés plasmoniques proposées peuvent être appliquées dans la détection de substances biochimiquesLocalized surface plasmons (LSP) are used to control and concentrate the electromagnetic field in small volumes of matter. This is a very interesting property in the context of biophotonics. Indeed, it allows an enhancement of the light-matter interaction at the cell scale, or even at a single molecule scale. The technological challenge is to propose optical devices able to efficiently couple light into localized plasmonic modes and to improve the detection of signals resulting from the interaction between the confined light and the analyte under detection.In this thesis work, we theoretically and experimentally study the guiding and confinement properties of light in periodic arrays of metallic nanowires of rectangular and triangular (nanocones) cross section that support localized plasmons. These nanowires are integrated in a photonic circuit that enables an efficient light coupling. The extinction spectra of the plasmonic resonances are directly obtained by analyzing the transmitted light in the device. By making use of the Fourier modal method, we perform an exhaustive theoretical study of the plasmonic Bloch modes that propagate due to the near-field coupling of the localized plasmons resonances. It is demonstrated that for the metallic nanocones, the optical field can be strongly enhanced by a controllable tip effect and remarkably intense
46
Johnson, Claire. "Studies towards the synthesis of photosensitizers with improved biodistribution and light-absorbing properties." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ27170.pdf.
Full text
47
Baiocco, Giorgio <1984>. "Towards a Reconstruction of Thermal Properties of Light Nuclei from Fusion - Evaporation reactions." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4295/.
Full textAbstract:
This thesis work has been developed in the framework of a new experimental campaign, proposed by the NUCL-EX Collaboration (INFN III Group), in order to progress in the understanding of the statistical properties of light nuclei, at excitation energies above particle emission threshold, by measuring exclusive data from fusion-evaporation reactions.
The determination of the nuclear level density in the A~20 region,
the understanding of the statistical behavior of light nuclei with excitation energies ~3 A.MeV,
and the measurement of observables linked to the presence of cluster structures of nuclear excited
levels are the main physics goals of this work.
On the theory side, the contribution to this project given by this work lies in the development of a dedicated Monte-Carlo Hauser-Feshbach code for the evaporation of the compound nucleus.
The experimental part of this thesis has consisted in the participation to the measurement 12C+12C at 95 MeV beam energy, at Laboratori Nazionali di Legnaro - INFN, using the GARFIELD+Ring Counter(RCo) set-up, from the beam-time request to the data taking, data reduction, detector calibrations and data analysis.
Different results of the data analysis are presented in this thesis, together with a theoretical study of the system, performed with the new statistical decay code.
As a result of this work, constraints on the nuclear level density at high excitation energy
for light systems ranging from C up to Mg are given. Moreover, pre-equilibrium effects, tentatively interpreted as alpha-clustering effects, are put in evidence, both in the entrance channel of the reaction and in the dissipative dynamics on the path towards thermalisation.
48
Berry, Andrew Edward. "Towards a molecular mechanism for light induction of gene transcription in Myxococcus xanthus." Thesis, University of Warwick, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340067.
Full text
49
Kuhle, Jens. "Towards quantifying axonal damage in blood samples from patients with neurological diseases." Thesis, Queen Mary, University of London, 2015. http://qmro.qmul.ac.uk/xmlui/handle/123456789/9085.
Full textAbstract:
Reliable biomarkers of axonal damage are urgently needed in neurological diseases. Neurofilaments (Nf) are specific structural elements of neurons composed of at least three subunits: Nf light chain (NfL), Nf medium and Nf heavy chain (NfH). This PhD aimed to characterise NfL levels and their correlation with clinical features in patients with neurological diseases with a different rate of progression and following and under different treatment regimes. An important aim was also to develop a bioassay for NfL measurements in blood. Cerebrospinal fluid (CSF) NfL levels discriminated patients with a clinically isolated syndrome (CIS) (p=0.001) or multiple sclerosis (MS) (p=0.035) from healthy controls more efficiently, and was more sensitive to change after natalizumab therapy (p<0.0001) than CSF NfH (p=0.002). Further, CSF NfL levels decreased in fingolimodtreated MS patients (p=0.001), but not in those receiving placebo (p=0.433). Based on these findings, a sensitive method for the detection of NfL in serum was developed and validated. Patients with neurological diseases had higher serum NfL values than controls. In acute spinal cord injury (SCI), serum NfL levels correlated with injury severity and long-term motor outcome, and Minocycline treatment was associated with decreased NfL levels in complete SCI patients compared to placebo. Finally, I found that serum NfL levels were higher in CIS patients than in healthy controls but did not predict conversion to clinically definite MS (CDMS). Independent predictors of CDMS were instead oligoclonal bands, number of T2 lesions and age at CIS. Lower 25-OHvitamin D levels were associated with CDMS in univariate analysis, but this was attenuated in the multivariate model. In conclusion, NfL proved to be an analytically stable protein which is an important prerequisite for biomarkers. The role of NfL quantification as a surrogate measure of neuroaxonal damage is corroborated by my findings and further supports the usefulness of NfL as a putative biomarker of axonal damage in various neurological diseases.
50
Suzuki, Hajime. "Design of novel semiconductor photocatalysts and cocatalysts toward efficient water splitting under visible light." Kyoto University, 2018. http://hdl.handle.net/2433/232052.
Full text