• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 401
  • 79
  • 38
  • 32
  • 21
  • 19
  • 12
  • 7
  • 6
  • 5
  • 5
  • 4
  • 4
  • 3
  • 3
  • Tagged with
  • 753
  • 87
  • 80
  • 78
  • 77
  • 72
  • 65
  • 58
  • 50
  • 47
  • 46
  • 45
  • 40
  • 39
  • 39
  • 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.
321

Visual Stereo Odometry for Indoor Positioning

Johansson, Fredrik January 2012 (has links)
In this master thesis a visual odometry system is implemented and explained. Visual odometry is a technique, which could be used on autonomous vehicles to determine its current position and is preferably used indoors when GPS is notworking. The only input to the system are the images from a stereo camera and the output is the current location given in relative position. In the C++ implementation, image features are found and matched between the stereo images and the previous stereo pair, which gives a range of 150-250 verified feature matchings. The image coordinates are triangulated into a 3D-point cloud. The distance between two subsequent point clouds is minimized with respect to rigid transformations, which gives the motion described with six parameters, three for the translation and three for the rotation. Noise in the image coordinates gives reconstruction errors which makes the motion estimation very sensitive. The results from six experiments show that the weakness of the system is the ability to distinguish rotations from translations. However, if the system has additional knowledge of how it is moving, the minimization can be done with only three parameters and the system can estimate its position with less than 5 % error.
322

Chronicling the Shifts: Using the Body Lens to Analyze Policy for High Need Women Offenders

Durrell, Jennifer E A 17 May 2011 (has links)
This thesis uses an exploratory case study design to chronicle the shifts, recognition, and implementation of programs, tools and policies designed for high need federally sentenced women in Canada that were created after 1990, in accordance with or opposed to the gender specific principles outlined in the Creating Choices (1990) report. The body lens is used as an analytic tool to deconstruct eleven of the most pertinent documents regarding policy and strategy for high need women offenders that were implemented by the Correctional Service of Canada (CSC) personnel and the Office of the Correctional Investigator (OCI) over the past twenty years. Coding of a wide range of documents reveals that despite appearing to be rhetorically progressive, CSC’s attempt at creating a women-centered mental health strategy uses contradictory disciplinary techniques that control and restrain the bodies of federally sentenced women in hopes of normalizing the behaviours of high need women. The policies imposed by CSC for high need women offenders fail to make any substantial changes in women’s prison reform and resulted in a different form of regulation and control. High need women offenders are imprisoned in their own bodies.
323

The Effects of 1-(5-Iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML-7) on the Lens During Avian Accommodation In Situ

Luck, Sara 02 December 2009 (has links)
A previous study in chickens revealed that myosin light chain kinase (MLCK), f actin, and myosin are found on the crystalline lens. Their polygonal arrangement at the posterior surface resembles a muscle tissue, which suggests that these proteins may have a contractile role in accommodation. The ciliary muscle in chickens is skeletal in nature and, therefore, chickens were used to test the hypothesis that contractile microfilaments play a role in accommodation. Ciliary nerve-induced accommodation was measured in the presence of an MLCK inhibitor 1-(5-Iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML-7). Eyes of 6-day old white Leghorn chickens (gallus gallus domesticus) were enucleated in Tyrode’s saline solution while keeping the ciliary nerve intact. One eye was treated with ML-7 and the other eye was treated with vehicle only. Three concentrations of ML-7 were used: 1 µM, 10 µM, and 100 µM. Two experiments were carried out, one including a (3×10 min) wash and one without. Focal lengths of the vehicle- and ML-7-treated eyes were measured before, during and after accommodation. Immunoblots were used to detect the amount of phosphorylated myosin with and without the inhibitor. Focal lengths for accommodation were shorter than those at rest (p<0.001). In the wash experiment, vehicle-treated eyes had higher accommodative amplitudes compared to ML-7-treated eyes for all three dosage groups. In the no-wash experiment, only the 1 µM group demonstrated the same trend as the wash experiment. For the 10 µM and 100 µM groups, ML-7-treated eyes had higher accommodative amplitudes compared to vehicle-treated eyes. Immunoblots revealed varying amounts of inhibition within pairs of eyes as well as between birds for both experiments. Results from this experiment indicate that ML-7 was not effective at determining whether contractile microfilaments found on the lens contribute to accommodation.
324

It's About Letting Go of Control : A Practice Lens Perspective on a Municipal Social Intranet

Lövgren, Daniel January 2012 (has links)
Social intranets have over the last few years gained momentum in popularity and are rapidly being implemented in organizations around the world. Research is mainly limited to consist of analyses of use of particular technologies, and is mostly conducted in relation to private organizations. This thesis provides an analysis of the implementation and use of a social intranet in a public organization. In February 2012, Uppsala municipality (Sweden) implemented their new social intranet Insidan for all their employees. The idea is of enhancing the everyday working context and to increase the participation throughout the organization. Wanda Orlikowski’s theory of the practice lens is applied to situate and understand the role of the intranet. The practice lens is relevant as it acknowledges human agency, context and the technological inscriptions to understand the role of technology in organizations. The findings are further elaborated in relation to Andrew McAfee’s Enterprise 2.0. Interviews with users, management and designers, as well as document analysis are used to extract data in a case study design. The results show that Insidan contains central aspects of what constitutes a social intranet. The practice of Insidan enhances user aspects of communication, collaboration and cooperation. One technological feature, the cooperation room, is especially successful. It is a space wherein user share documents and talk openly in a semi-private environment. However, other tools, like blogs, are not adapted to any significant level. Perceived benefits for personal work is relevant to adoption. Findings on insecurity towards what is appropriate to contribute as content are seen to limit active user participation in conversations. Role models for activity are called for. Users are more confident to converse in closed groups. Thus, social connections and communication are given a new arena, but it often takes place in familiarized circles of people (e.g. project groups, office colleagues). This thesis provides knowledge and insights into an exciting and growing field of research. It also provides important insights from an implementation in a public organization – a context not extensively investigated.
325

The Effects of 1-(5-Iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML-7) on the Lens During Avian Accommodation In Situ

Luck, Sara 02 December 2009 (has links)
A previous study in chickens revealed that myosin light chain kinase (MLCK), f actin, and myosin are found on the crystalline lens. Their polygonal arrangement at the posterior surface resembles a muscle tissue, which suggests that these proteins may have a contractile role in accommodation. The ciliary muscle in chickens is skeletal in nature and, therefore, chickens were used to test the hypothesis that contractile microfilaments play a role in accommodation. Ciliary nerve-induced accommodation was measured in the presence of an MLCK inhibitor 1-(5-Iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML-7). Eyes of 6-day old white Leghorn chickens (gallus gallus domesticus) were enucleated in Tyrode’s saline solution while keeping the ciliary nerve intact. One eye was treated with ML-7 and the other eye was treated with vehicle only. Three concentrations of ML-7 were used: 1 µM, 10 µM, and 100 µM. Two experiments were carried out, one including a (3×10 min) wash and one without. Focal lengths of the vehicle- and ML-7-treated eyes were measured before, during and after accommodation. Immunoblots were used to detect the amount of phosphorylated myosin with and without the inhibitor. Focal lengths for accommodation were shorter than those at rest (p<0.001). In the wash experiment, vehicle-treated eyes had higher accommodative amplitudes compared to ML-7-treated eyes for all three dosage groups. In the no-wash experiment, only the 1 µM group demonstrated the same trend as the wash experiment. For the 10 µM and 100 µM groups, ML-7-treated eyes had higher accommodative amplitudes compared to vehicle-treated eyes. Immunoblots revealed varying amounts of inhibition within pairs of eyes as well as between birds for both experiments. Results from this experiment indicate that ML-7 was not effective at determining whether contractile microfilaments found on the lens contribute to accommodation.
326

Mechanics of Complex Hydraulic Fractures in the Earth's Crust

Sim, Youngjong 24 August 2004 (has links)
Hydraulic fracturing is an important and abundant process in both industrial applications and natural environments. The current work is the first systematic quantitative study of the effect of interaction in and between complex hydraulic fractures at different spatial scales. A mathematical model, based on the boundary collocation method, has been developed. The model has been employed for a typical field case, a highly segmented vein. This vein is well-mapped, and therefore, represents a well constrained example. The computed apertures are compared to the measured apertures. By using the simplest constitutive model, based on an ideal elastic material, and including the effect of interaction between the segments, it was possible to obtain an excellent match at all considered scales. It was also shown that the concept of effective fracture, as currently accepted in the literature, is not always applicable and may lead to unbounded inaccuracy. Unfortunately, in most cases, very little (if any) directly measured data on fracture and material properties is available. An important example of such a weakly constrained case, involving hydraulic fracturing, is diking beneath the seafloor at mid-oceanic ridges. In this study, it is shown that the commonly accepted scenario of a dike propagating from the center of the pressurized magma chamber to the ocean floor is not consistent with conventional fracture mechanics due to the fact that the chamber has the shape of a thin lens. Even at such a large scale (i.e., a kilometer or more), the mechanical principles of elastic interaction appear to be applicable. Since diking is likely to generate a region of high permeability near its margin, in addition to heat, the ongoing hydrothermal activity becomes localized. Our modeling suggests the probable positions of the propagating dikes. Consequently, comparing the observed locations of hydrothermal sites with respect to that of the magma chamber could be useful for constraining the mechanisms of magma lens evolution.
327

A Study of the Grinding Process for the Optical-Fiber Endface with Double-Variable Curvatures

Chen, Jun-Hong 02 September 2010 (has links)
Mechanical grinding process is the most popular way to fabricate the fiber micro lenses, although there are some other methods, such as chemical etching, laser machining and focused ion beam micro-cutting. Mechanical grinding has its uniqueness in grinding Conical-Wedge-Shaped Fiber Endface, fiber endface with polygon-cone-shape, and fiber endface with double-variable curvatures. The double-variable curvatures fiber endface polisher, designed and manufactured by Mechanism Design Lab of NSYSU, is employed in this study. The normal force of the fiber endface is derived firstly and then the experimental parameters and data are substituted into the material removal rate (M.R.R.) formula to obtain M.R.R. and the Preston¡¦s constant K. The process parameters of the feed rate and polishing time on the fabrication of the fiber endface are analyzed. The polisher is calibrated and adjusted to improve the precision of the optical-fiber endface. A fiber endface with double-variable curvature is successfully fabricated in a single grinding process by properly controlling the fiber rotation angle, inclining angle, and the distant between the endface and the grinding film simultaneously. The grinding process developed in this study can be applied for fabricating optical fiber lenses in fiber optics communication as well as different types of micro probes, and micro spectroscopefors in other applications.
328

Study of Citizen Participate on New Media

Huang, Shih-Wei 21 July 2011 (has links)
In recent years, New Media such as internet not only impacted old media but also widely used by citizenship. For example, Thousands of internet users set up a voluntary "Morakot Typhoon disaster network center" raised supplies and reported the latest disaster in remote mountainous areas in 2009. January 2011 People in Egypt also used a network of new media to raise citizen to demonstrate their anger of government, they finally attracted international attention. These phenomena have demonstrated new media's power and influence. ¡@¡@This study explores the factors and cognitive attitudes of citizens when they through a network use new media to participate in public affairs. The factors were chosen from literatures and corresponded to PAM (integrated public affair management framework). Five decision-making variables (cues) of this study are "selfish - altruism", "support from peer", "self-ability", "anonymous degree ", and "the issue of topic". Questionnaire was based on Social Judgment Theory, SJT. Both physical survey questionnaires and internet questionnaires were disseminated to new media users. Total questionnaires are 152 and valid questionnaires are 88. Through statistical software policy PC to understand the subject's decision-making for these five variables in the cognitive approach. The results are as follows: 1. In the average weights, the most important cue for all groups is "anonymous degree" followed by "self-ability", "selfish - altruism", "support from peer", and "the issue of topic". 2. In the judgment functions, all groups have positive attitude toward the three cues: "selfish - altruism", "self-ability" and "anonymous degree". All groups have U-curve attitude toward the cue:"support from peer". All groups have positive attitude and U-curve attitude toward the cue:"the issue of topic".
329

Computation of the Optical Point Spread Function of a Ball Lens

Lien, Chun-Yu 24 September 2012 (has links)
In this thesis, we analyze the simplest optical imaging system: a ball lens. The traditional method of using a geometric optics analysis on an optical system only gives the roughest qualitative solution due to the lack of consideration of wave properties. Therefore, for accurate quantitative results, we need to analyze said system with a complete wave theory approach. The reason that we chose a ball lens as the focus of this research is due to its spherical symmetry properties which allows us to rigorously investigate it with different analytic methods. We will apply geometric optics, Fourier optics, scalar wave optics, and electromagnetic optics methods to compute the point spread functions (PSF) of a ball lens under the assumption that the point source is isotropic. We will follow up by predicting the spot sizes that correspond to each mean. First, with geometric optics (GO), we apply the analytic ray tracing method to correlate the origins of light rays passing through the ball lens to their respective positions on the receptive end. We can then evaluate the energy distribution function by gathering the density of rays on image plane. Second, in the theory of Fourier optics (FO), to obtain the analytic formula of the point spread function, the integral kernel can be approximated as the Fresnel integral kernel by means of paraxial approximation. Compared to GO, the results from FO are superior due to the inclusion of wave characteristics. Furthermore, we consider scalar wave optics by directly solving the inhomogeneous Helmholtz equation which the scalar light field should satisfy. However, the light field is not assigned to an exact physical meaning in the theory of scalar wave optics, so we reasonably require boundary conditions where the light field function and its first derivative are continuous everywhere on the surface of ball lens. Finally, in the theory of electromagnetic optics (EMO), we consider the polarization of the point source, and the two kinds of Hertz vectors and , both of which satisfy inhomogeneous Helmholtz equation, and are derived from Maxwell¡¦s equations in spherical structures. In contrast with the scalar wave optics, the two Hertz vectors are defined concretely thus allowing us to assign exact boundary conditions on the interface. Then the fields corresponding to and are averaged as the final point spread function.
330

SURFACE PLASMON COUPLED SENSOR AND NANOLENS

Ko, Hyungduk 2009 May 1900 (has links)
This dissertation consists of two topics. One is a "Multi-pass Fiber Optic Surface Plasmon Resonance Sensor (SPR)" and the other is a "Nano-metallic Surface Plasmon Lens." Since both topics involved surface plasmon, the title of this dissertation is named "Surface plasmon coupled sensor and nanolens." For a multi-pass fiber optic SPR sensor, a fiber optic 4-pass SPR sensor coupled with a field-assist capability for detecting an extremely low concentration of charged particles is first demonstrated. The multipass feature increases the sensitivity by a factor equal to the number of passes. The field-assist feature forces charged particles/molecules to the SPR surface, increasing the sensitivity by an additional factor of about 100. Overall, the sensitivity exceeds the one-pass SPR device by a factor of about 400. A 10 pM concentration of 47 nm diameter polystyrene (PS) latex beads and 1 ?M concentration of salt dissolved in DI water were detected within a few seconds by the combined system. The equivalent index resolution for atomic size corresponding to ionized chlorine in salt is 10-8. This technique offers the potential for sensitive and fast detection of biomolecules in a solution. Secondly, a 44-pass fiber optic surface plasmon resonance (SPR) sensor coupled with a field-assist capability for measurement of refractive index change due to positive and negative ions is shown. The field-assist feature forces ions to the SPR surface, causing the SPR signal response to change which reflects a decrease or increase in refractive index depending on whether positive or negative ions are being attracted to the surface. This technique offers the potential for the sensitive detection of cations and anions in a solution. For a nano-metallic surface plasmon lens, we analyze the transmission of a normally incident plane wave through an Ag/dielectric layered concentric ring structure using finite difference time domain (FDTD) analysis. The dependency of the transmission efficiency on the refractive index in slit is studied. The numerical analysis indicates that the focusing beyond diffraction limit is found even at the extended focal length comparable to the distance of 7" from the exit plane using a circularly polarized coherent plane wave, ?=405 nm. Especially, compared to an Ag-only structure, the Ag/ LiNbO3 structure amplifies the transmission power by a factor of 6. Therefore, this Ag/dielectric layered lens has the potential for significantly higher resolution imaging and optical data storage.

Page generated in 0.0615 seconds