• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 873
  • 65
  • 60
  • 33
  • 24
  • 12
  • 6
  • 4
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 1348
  • 551
  • 516
  • 325
  • 290
  • 282
  • 200
  • 198
  • 147
  • 143
  • 127
  • 125
  • 124
  • 103
  • 102
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
391

Sensorsystem till hinderhanterande robot / Sensor System for Obstacle Handling Robot

Lichtermann, Johan January 2005 (has links)
The projects goal is to construct and program a robot that is controlled from a computer but also have an obstacle handling function that allows the robot to navigate around the object by itself. The robot is a simple construction and the number of components and functions is kept at a minimum. A tricycle construction was chosen because it’s the simplest. Communication between the robot and the computer also kept as simple as possible. / Målet med projektet är att konstruera och programmera en robot som går att styra från en dator men det skall även finnas en hinderhanterande funktion som gör att roboten kan åka runt hinder av sig själv. Roboten är en enkel konstruktion där antalet komponenter och funktioner hålls nere till ett minimum. En trehjuling valdes då det är den enklaste konstruktionen. Kommunikationen mellan roboten och datorn hålls också så enkel som möjligt.
392

Wireless ECG

mediavilla pons, emiliano elias January 2009 (has links)
<p>This document contains the development of an amplifier for an ECG-signal and interfacing it to wireless communication. The purpose of this project is to get a clear ECG-signal without any noise, save it and send it through wireless communication.A challenge of the wireless communication unit is to send as little information as possible to make the communication faster, without loss of information in the ECG-signal.The context for this project is the integration of wireless communication in medical applications for home healthcare. This means that, patients are no longer bound to a specific healthcare location where they are monitored by medical instruments. Wireless communication will not only provide them with safe and accurate monitoring, but also the freedom of movement.</p>
393

Towards a single-mode dispensed polymer optical waveguide [electronic resource] / by Jill Michelle Kalajian.

Kalajian, Jill Michelle. January 2003 (has links)
Title from PDF of title page. / Document formatted into pages; contains 59 pages. / Thesis (M.S.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Dispensed organic polymer optical waveguides suitable for single-mode operation were recently fabricated. Different dispensing pressures, polymers, and dispensing tips were used in the drawing method. The waveguides were measured to be approximately 16[mu] wide and 0.8[mu] tall. This is significantly smaller than previously reported dimensions of 300[mu] x 3.5[mu] waveguides fabricated with a similar dispensed polymer method. The waveguides were also found to be suitable for single-mode operation through a series of approximate calculations . This is also something previously not achieved with the larger waveguides. This novel approach to waveguide fabrication could reduce the expense and time of creating single mode waveguides for rapid development applications. It will also allow the waveguides to be fabricated to be flexible as well as doped to be active devices. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.
394

Novel organic materials for molecular electronics and photonics /

NG, Man Kit. January 2002 (has links)
Thesis (Ph. D.)--University of Chicago, Department of Chemistry, 2002. / Includes bibliographical references. Also available on the Internet.
395

Self-assembly approaches to photonic structures /

Yin, Yadong. January 2002 (has links)
Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 187-201).
396

Silicon nanomembrane for high performance conformal photonic devices

Xu, Xiaochuan 02 March 2015 (has links)
Inorganic material based electronics and photonics on unconventional substrates have shown tremendous unprecedented applications, especially in areas that traditional wafer based electronics and photonics are unable to cover. These areas range from flexible and conformal consumer products to biocompatible medical devices. This thesis presents the research on single crystal silicon nanomembrane photonics on different substrates, especially flexible substrates. A transfer method has been developed to transfer silicon nanomembrane defect-freely onto glass and flexible polyimide substrates. Using this method, intricate single crystal silicon nanomembrane device, such as photonic crystal microcavity, has been transferred onto flexible substrates. To test the device, subwavelength grating couplers are designed and implemented to couple light in and out of the transferred waveguides with high coupling efficiency. The cavity shows a quality factor ~ 9000 with water cladding and ~30000 with glycerol cladding, which is comparable to the same cavity demonstrated on silicon-on-insulator platform, indicating the high quality of the transferred silicon nanomembrane. The device could be bended to a radius less than 15 mm. The experiments show that the resonant wavelength shifts to longer wavelength under tensile stress, while it shifts to shorter wavelength under compressive stress. The sensitivity of the cavity is ~70 nm/RIU, which is independent of bending radius. This demonstration opens vast possibilities for a whole new range of high performance, light-weight and conformal silicon photonic devices. The techniques and devices (e.g. wafer bonding, stamp printing, subwavelength grating couplers, and modulator) generated in the research can also be beneficial for other research fields. / text
397

Wavelength-selective micro- and nano-photonic devices for wavelength division multiplexing networks

Jiang, Wei 28 August 2008 (has links)
Not available / text
398

Photonic crystal waveguides based active and passive devices for phased array antenna systems

Jiang, Yongqiang 28 August 2008 (has links)
Not available / text
399

Optical resonators and quantum dots: and excursion into quantum optics, quantum information and photonics

Bianucci, Pablo, 1975- 28 August 2008 (has links)
Modern communications technology has encouraged an intimate connection between Semiconductor Physics and Optics, and this connection shows best in the combination of electron-confining structures with light-confining structures. Semiconductor quantum dots are systems engineered to trap electrons in a mesoscopic scale (the are composed of [approximately] 10000 atoms), resulting in a behavior resembling that of atoms, but much richer. Optical microrseonators are engineered to confine light, increasing its intensity and enabling a much stronger interaction with matter. Their combination opens a myriad of new directions, both in fundamental Physics and in possible applications. This dissertation explores both semiconductor quantum dots and microresonators, through experimental work done with semiconductor quantum dots and microsphere resonators spanning the fields of Quantum Optics, Quantum Information and Photonics; from quantum algorithms to polarization converters. Quantum Optics leads the way, allowing us to understand how to manipulate and measure quantum dots with light and to elucidate the interactions between them and microresonators. In the Quantum Information area, we present a detailed study of the feasibility of excitons in quantum dots to perform quantum computations, including an experimental demonstration of the single-qubit Deutsch-Jozsa algorithm performed in a single semiconductor quantum dot. Our studies in Photonics involve applications of microsphere resonators, which we have learned to fabricate and characterize. We present an elaborate description of the experimental techniques needed to study microspheres, including studies and proof of concept experiments on both ultra-sensitive microsphere sensors and whispering gallery mode polarization converters. / text
400

Optical excitation of surface plasmon polaritons on novel bigratings

Constant, Thomas J. January 2013 (has links)
This thesis details original experimental investigations in to the interaction of light with the mobile electrons at the surface of metallic diffraction gratings. The gratings used in this work to support the resultant trapped surface waves (surface plasmon polaritons), may be divided into two classes: ‘crossed’ bigratings and ‘zigzag’ gratings. Crossed bigratings are composed of two diffraction gratings formed of periodic grooves in a metal surface, which are crossed at an angle relative to one another. While crossed bigratings have been studied previously, this work focuses on symmetries which have received comparatively little attention in the literature. The gratings explored in this work possesses two different underlying Bravais lattices: rectangular and oblique. Control over the surface plasmon polariton (SPP) dispersion on a rectangular bigrating is demonstrated by the deepening of one of the two constituent gratings. The resulting change in the diffraction efficiency of the surface waves leads to large SPP band-gaps in one direction across the grating, leaving the SPP propagation in the orthogonal direction largely unperturbed. This provides a mechanism to design surfaces that support highly anisotropic propagation of SPPs. SPPs on the oblique grating are found to mediate polarisation conversion of the incident light field. Additionally, the SPP band-gaps that form on such a surface are shown to not necessarily occur at the Brillouin Zone boundaries of this lattice, as the BZ boundary for an oblique lattice is not a continuous contour of high-symmetry points. The second class of diffraction grating investigated in this thesis is the new zigzag grating geometry. This grating is formed of sub-wavelength (non-diffracting) grooves that are ‘zigzagged’ along their length to provide a diffractive periodicity for visible frequency radiation. The excitation and propagation of SPPs on such gratings is investigated and found to be highly polarisation selective. The first type of zigzag grating investigated possesses a single mirror plane. SPP excitation to found to be dependant on which diffracted order of SPP is under polarised illumination. The formation of SPP band-gaps is also investigated, finding that the band-gap at the first Brillouin Zone boundary is forbidden by the grating’s symmetry. The final grating considered is a zigzag grating which possesses no mirror symmetry. Using this grating, it is demonstrated that any polarisation of incident light may resonantly drive the same SPP modes. SPP propagation on this grating is found to be forbidden in all directions for a range of frequencies, forming a full SPP band-gap.

Page generated in 0.0513 seconds