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Articles 91 - 102 of 102
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Applications Of Linear And Nonlinear Optical Effects In Liquid Crystals, Hakob Sarkissian
Applications Of Linear And Nonlinear Optical Effects In Liquid Crystals, Hakob Sarkissian
Electronic Theses and Dissertations
Liquid crystals have been a major subject of research for the past decades. Aside from the variety of structures they can form, they exhibit a vast range of optical phenomena. Many of these phenomena found applications in technology and became an essential part of it. In this dissertation thesis we continue the line to propose a number of new applications of optical effects in liquid crystals and develop their theoretical framework. One such application is the possibility of beam combining using Orientational Stimulated Scattering in a nematic liquid crystal cell. Our numerical study of the OSS process shows that normally …
Predicting Surface Scatter Using A Linear Systems Formulation Of Non-Paraxial Scalar Diffraction, Andrey Krywonos
Predicting Surface Scatter Using A Linear Systems Formulation Of Non-Paraxial Scalar Diffraction, Andrey Krywonos
Electronic Theses and Dissertations
Scattering effects from rough surfaces are non-paraxial diffraction phenomena resulting from random phase variations in the reflected wavefront. The ability to predict these effects is important in a variety of applications including x-ray and EUV imaging, the design of stray light rejection systems, and reflection modeling for rendering realistic scenes and animations of physical objects in computer graphics. Rayleigh-Rice (small perturbation method) and Beckmann-Kirchoff (Kirchhoff approximation) theories are commonly used to predict surface scatter effects. In addition, Harvey and Shack developed a linear systems formulation of surface scatter phenomena in which the scattering behavior is characterized by a surface transfer …
Image-Based Material Editing, Erum Khan
Image-Based Material Editing, Erum Khan
Electronic Theses and Dissertations
Photo editing software allows digital images to be blurred, warped or re-colored at the touch of a button. However, it is not currently possible to change the material appearance of an object except by painstakingly painting over the appropriate pixels. Here we present a set of methods for automatically replacing one material with another, completely different material, starting with only a single high dynamic range image, and an alpha matte specifying the object. Our approach exploits the fact that human vision is surprisingly tolerant of certain (sometimes enormous) physical inaccuracies. Thus, it may be possible to produce a visually compelling …
Additive Lithography Fabrication And Integration Of Micro Optics, Mahesh Pitchumani
Additive Lithography Fabrication And Integration Of Micro Optics, Mahesh Pitchumani
Electronic Theses and Dissertations
Optical elements are the fundamental components in photonic systems and are used to transform an input optical beam into a desired beam profile or to couple the input beam into waveguides, fibers, or other optical systems or devices. Macroscopic optical elements are easily fabricated using grinding and polishing techniques, but few methods exist for inexpensive fabrication of micro optical elements. In this work we present an innovative technique termed Additive Lithography that makes use of binary masks and controlled partial exposures to sculpt photoresist into the desired optical surface relief profile. We explore various masking schemes for fabricating a variety …
Up-Conversion In Rare-Earth Doped Micro-Particles Applied To New Emissive 2d Dislays, Anne Milliez
Up-Conversion In Rare-Earth Doped Micro-Particles Applied To New Emissive 2d Dislays, Anne Milliez
Electronic Theses and Dissertations
Up-conversion (UC) in rare-earth co-doped fluorides to convert diode laser light in the near infrared to red, green and blue visible light is applied to make possible high performance emissive displays. The infrared-to-visible UC in the materials we study is a sequential form of non-linear two photon absorption in which a strong absorbing constituent absorbs two low energy photons and transfers this energy to another constituent which emits visible light. Some of the UC emitters' most appealing characteristics for displays are: a wide color gamut with very saturated colors, very high brightness operation without damage to the emitters, long lifetimes …
Algorithms For Haplotype Inference And Block Partitioning, Satya Ravi Vijaya
Algorithms For Haplotype Inference And Block Partitioning, Satya Ravi Vijaya
Electronic Theses and Dissertations
The completion of the human genome project in 2003 paved the way for studies to better understand and catalog variation in the human genome. The International HapMap Project was started in 2002 with the aim of identifying genetic variation in the human genome and studying the distribution of genetic variation across populations of individuals. The information collected by the HapMap project will enable researchers in associating genetic variations with phenotypic variations. Single Nucleotide Polymorphisms (SNPs) are loci in the genome where two individuals differ in a single base. It is estimated that there are approximately ten million SNPs in the …
Discrimination Of Automobile Carpet Fibers Using Multiple Analytical Techniques And The Subsequent Creation Of A Searchable Data, Derek Dorrien
Discrimination Of Automobile Carpet Fibers Using Multiple Analytical Techniques And The Subsequent Creation Of A Searchable Data, Derek Dorrien
Electronic Theses and Dissertations
Forensic fiber examination is an important part of trace evidence analysis. Fibers may be recovered from a crime scene that could link a particular suspect to the scene. Clothing fibers are most frequently encountered but automobile carpeting fibers may also be recovered. An understanding of the frequency of occurrence and the discrimination power of different analytical techniques is needed in order to better establish the evidentiary value of automobile carpet fiber evidence. Seventy-five automobile carpet fiber samples were analyzed using a series of techniques ranging from nondestructive to destructive. These techniques included polarized light microscopy, fluorescence microscopy, microspectrophotometry, Fourier-transform infrared …
Object Association Across Multiple Moving Cameras In Planar Scenes, Yaser Sheikh
Object Association Across Multiple Moving Cameras In Planar Scenes, Yaser Sheikh
Electronic Theses and Dissertations
In this dissertation, we address the problem of object detection and object association across multiple cameras over large areas that are well modeled by planes. We present a unifying probabilistic framework that captures the underlying geometry of planar scenes, and present algorithms to estimate geometric relationships between different cameras, which are subsequently used for co-operative association of objects. We first present a local1 object detection scheme that has three fundamental innovations over existing approaches. First, the model of the intensities of image pixels as independent random variables is challenged and it is asserted that useful correlation exists in intensities of …
Quantitative High-Angle Annular Dark Field Scanning Transmission To Electron Microscopy For Materials Science, Rumyana Petrova
Quantitative High-Angle Annular Dark Field Scanning Transmission To Electron Microscopy For Materials Science, Rumyana Petrova
Electronic Theses and Dissertations
Scanning transmission electron microscopy (STEM) has been widely used for characterization of materials; to identify micro- and nano-structures within a sample and to analyze crystal and defect structures. High-angle annular dark field (HAADF) STEM imaging using atomic number (Z) contrast has proven capable of resolving atomic structures with better than 2 A lateral resolution. In this work, the HAADF STEM imaging mode is used in combination with multislice simulations. This combination is applied to the investigation of the temperature dependence of the intensity collected by the HAADF detector in silicon, and to convergent beam electron diffraction (CBED) to measure the …
A Geochemical, Isotopic, And Petrologic Study Of A Watershed With Arsenic-Enriched Ground Water In Northport, Maine, Gail Elizabeth Lipfert
A Geochemical, Isotopic, And Petrologic Study Of A Watershed With Arsenic-Enriched Ground Water In Northport, Maine, Gail Elizabeth Lipfert
Electronic Theses and Dissertations
High mean arsenic concentrations up 26.6 ¹mol/L (1990 ¹g/L) occur in ground water within a watershed at Kelly's Cove, Northport, Maine, USA. The Kelly's Cove watershed is a fractured-bedrock system composed of sul¯dic schist with granitic to dioritic intrusions. Arsenic is enriched in these rocks up to 1050 mg kg¡1 (average: 68 mg kg¡1). The distribution of arsenic in the bedrock appears to be controlled by the presence of arsenopyrite and arsenian pyrite, that occur primarily in post-metamorphic, tourmaline + quartz § carbonate veins and the Kelly's Cove granite. Based on the metamorphic signature of the tourmaline chemistry and the …
Thermal And Mechanical Effects Of A Shallow Asthenosphere In The Acadian Orogen: An Investigation Through Numerical Modeling, Lucy E. Brown
Thermal And Mechanical Effects Of A Shallow Asthenosphere In The Acadian Orogen: An Investigation Through Numerical Modeling, Lucy E. Brown
Electronic Theses and Dissertations
A high-temperature region associated with Acadian deformation extends 200 km through north-central New England. The scale of this heat source is investigated in order to better understand the rheology and mechanics of deforming orogens. In central Maine, on the boundary of the high-temperature region, isograds in pelitic rocks are normal to the accretionary structures and record a steep northeast-southwest thermal gradient. The isogradic sequence, geobarometry, and the mineral assemblages indicate low-pressure, high-temperature metamorphism, moderately low pressures of 3 kbar, and temperatures ranging from 600º to 450ºC over a 10 km region. The spacing between these isograds and the temperature at …
The Geoarchaeological Setting Of The Sebasticook Lake Fish Weir Newport, Maine, Christopher Evan Miller
The Geoarchaeological Setting Of The Sebasticook Lake Fish Weir Newport, Maine, Christopher Evan Miller
Electronic Theses and Dissertations
A geophysical and coring survey of Sebasticook Lake, Newport, Maine, provides evidence of past human-landscape interactions associated with construction and use of a Middle Archaic to Middle Woodland period fish weir, located at the lake inlet. Geophysical methods employed included Seismic Reflection Profiling (SRP) and Sidescan Sonar (SSS) survey of the Sebasticook Lake basin, and Ground Penetrating Radar (GPR) survey of the fish weir site and lake inlet. Three cores were collected using a modified, square-rod Wright piston corer in the lake basin. The Sebasticook fish weir complex consists of >630 stone-tool-modified wooden stakes, driven into stiff underlying glacial mud …