Blowfish is a highly segmented neutron detector array consisting of 88 cells filled with BC-505 liquid scintillator. <p>The cells make up a spherical shape that covers approximately one quarter of the total solid angle of 4 pi steradians.<p> A high-priority measurement for Blowfish is the low energy contribution to the Gerasimov-Drell-Hearn (GDH) sum rule on the deuteron, which uses circularly polarized gamma rays. <p>The experimental data that needs to be collected are the absolute cross-sections when the gamma ray helicity and target polarization are parallel and anti-parallel. To extract absolute cross-sections from the data, it will be necessary to have characterized the efficiency of the detector.<p>Another measurement that would benefit from the efficiency calibration is the photodistegration of deuterium, which has already been performed. This measurement used linearly-polarized gamma rays at energies of 2.6, 3.5, 4.0 and 6.0 MeV. The relative cross-sections from this measurement provide much useful information, but to extract the absolute cross-sections the Blowfish efficiency calibration is needed. This thesis presents this efficiency calibration. <p> The efficiency calibration was done using a 252Cf source in a parallel plate ionization chamber over the energy range of 0 to 6 MeV. <p>To determine the absolute scale of the extracted efficiency curves, an efficiency analysis and simulation of a previously characterized BC-519 liquid scintillator cell needed to be performed along with a simulation of the Blowfish detector array. <p>The measured efficiencies were consistent with those predicted by the simulation over the desired energy range.

The use of polarized light for characterization of biological tissues has received increased attention in recent years due to the wealth of information available in the interactions of polarized light with tissue and the noninvasive nature of optical radiation. While the depolarizing effects of multiple scattering complicate the use of polarimetry in tissue, many biological constituents affect the polarization of light such as collagen, muscle fibers, and glucose. Thus, if the effects of scattering can be accounted for⎯or utilized in the analysis⎯polarized light can potentially be used as a probe of tissue status. This thesis presents advancements in the techniques for the simulation of polarized light in tissue-simulating media, and explores two biomedical applications. Previous Monte Carlo models for simulation of polarized light propagation in tissue-simulating media do not include the effects of birefringence and optical activity, two polarizing effects of useful diagnostic potential. To overcome this limitation, our model was extended to include both these effects simultaneously, and then experimentally validated using a novel polarization phantom system. The use of polarized light for characterization of the myocardium, and specifically towards monitoring stem cell regenerative treatments of myocardial infarction, was investigated experimentally as a novel application for polarimetry. The potential for this technique is based on the changes in myocardial structure that occur with infarction and subsequent regeneration, and the associated changes in tissue birefringence. The use of polarized light for noninvasive tissue analyte monitoring, particularly glucose, was also investigated based on the optical activity exhibited by many tissue analytes due to their chiral structure. In this study, a novel combined optical polarization and intensity approach was developed and tested on Monte Carlo simulated data. The studies presented in thesis introduce new methods for polarization simulation and analysis in biological tissue and demonstrate potential for polarimetry in monitoring myocardial regeneration and noninvasive measurements of tissue analytes.

The use of polarized light for characterization of biological tissues has received increased attention in recent years due to the wealth of information available in the interactions of polarized light with tissue and the noninvasive nature of optical radiation. While the depolarizing effects of multiple scattering complicate the use of polarimetry in tissue, many biological constituents affect the polarization of light such as collagen, muscle fibers, and glucose. Thus, if the effects of scattering can be accounted for⎯or utilized in the analysis⎯polarized light can potentially be used as a probe of tissue status. This thesis presents advancements in the techniques for the simulation of polarized light in tissue-simulating media, and explores two biomedical applications. Previous Monte Carlo models for simulation of polarized light propagation in tissue-simulating media do not include the effects of birefringence and optical activity, two polarizing effects of useful diagnostic potential. To overcome this limitation, our model was extended to include both these effects simultaneously, and then experimentally validated using a novel polarization phantom system. The use of polarized light for characterization of the myocardium, and specifically towards monitoring stem cell regenerative treatments of myocardial infarction, was investigated experimentally as a novel application for polarimetry. The potential for this technique is based on the changes in myocardial structure that occur with infarction and subsequent regeneration, and the associated changes in tissue birefringence. The use of polarized light for noninvasive tissue analyte monitoring, particularly glucose, was also investigated based on the optical activity exhibited by many tissue analytes due to their chiral structure. In this study, a novel combined optical polarization and intensity approach was developed and tested on Monte Carlo simulated data. The studies presented in thesis introduce new methods for polarization simulation and analysis in biological tissue and demonstrate potential for polarimetry in monitoring myocardial regeneration and noninvasive measurements of tissue analytes.

Introduction Very light jet is a hot subject growing stronger and stronger. The new type of air craft is an air plane that weighs less than 10000 pounds and uses a jet engine. Problem The student was proposed to designing a conceptual very light jet that could be used for inspiration and accepted the challenge. Method In this thesis the reader can follow the project progress in detail, the proposed methods and the results. The student divided the project into four activities analysis, creation, development and documentation. Result The project ended with a concept very light jet with simple specifications. Illustrations for inspirational usage and a simulation testing for verification of the proposed concept specifications.

This is a master thesis of the Master of Science degree program in Applied Physics and Electrical Engineering at Linköping University. The goal of this thesis is to find out how the Microsoft Kinect can be used as a part of a camera rig to create accurate 3D-models of an indoor environment. The Microsoft Kinect is marketed as a touch free game controller for the Microsoft Xbox 360 game console. The Kinect contains a color and a depth camera. The depth camera works by constantly projecting a near infrared dot pattern that is observed with a near infrared camera. In this thesis it is described how to model the near infrared projector pattern to enable external near infrared cameras to be used to improve the measurement precision. The depth data that the Kinect output have been studied to determine what types of errors it contains. The finding was that the Kinect uses an online calibration algorithm that changes the depth data.

Flocculation is an important part of the carbon cycle. It is therefore crucial to understand how flocculation is regulated and how different environmental factors impact. A dilemma is that it has been found difficult to measure flocculation experimentally. In this thesis, flocculation of dissolved organic carbon in a Swedish lake was measured in a series of laboratory experiments. The method used was Dynamic Light Scattering (DLS). DLS is used to determine the size distribution profile of, for instance, small particles in suspension. DLS measures Brownian motion and relates it to the particle size by measuring the fluctuation in scattering intensity. It is not very effective to measure the frequency spectrum contained in the intensity fluctuations directly, so instead, a digital auto correlator is used. Since factors such as pH, salinity and calcium chloride content varies in lakes and is thought to have an impact on flocculation, this was investigated as well. As pH was changed in a range of 3 to 9, small changes in size distribution could be detected. Salinity and calcium chloride content have quite an impact on flocculation. Time also has a great impact, samples that were set to rest for a week showed a significant increase in particle size. For DLS to work, the samples need to be filtered of centrifuged to get rid of large particles. Different types of filters were tested to see which filter material was the best to use. When filtering the water we only want to filter out the large particles. Natural organic matter has a hydrophobic component which adsorbs to some filter types but not to others. It is crucial to know which filters this hydrophobic component adsorbs to, so that the loss of dissolved organic carbon during filtration can be minimalized.

The thesis discusses the characteristics of natural light that are visible inside concrete buildings designed in the late twentieth century. The study addresses three major objectives. First is to identify the characteristics of natural light visible inside these spaces. Second is to understand the use of natural light to illuminate different spaces. Third is to explore the relation between the characteristics of natural light and the overall perception of the space. With these objectives in mind, a comprehensive literature review was done to develop the hypotheses for this thesis. The first hypothesis states that the overall perception of a space is affected by certain basic characteristics of natural light. The second hypothesis suggests that the overall character of a space can be enhanced by emphasizing the source of natural light as a visual element. To test these hypotheses, this thesis studies the effect of natural light in three buildings made out of reinforced concrete in the late twentieth century. The three buildings are the Chapel of Notre Dame du Haut Ronchamp by Le Corbusier, the Kimbell Art Museum by Louis I. Kahn and the Church of the Light by Tadao Ando. The method of analysis is based on the selection of a spatial envelope in each building that helps to provide an ideal framework for studying the effects of light. The method takes into consideration the principles of visual perception and the use of images depicting the varied effects of light inside the spatial envelope. The results of the analysis show that the three projects employ similar design principles to achieve some of the common effects of light, and the listed characteristics of light in relation to the overall perception of the space do not vary to a great extent when moving from one project to another. The emphasis on the source of natural light is a common and recurring theme in all three buildings. The thesis concludes that the results support the hypotheses, and that the quality of a space is dependent upon the way a designer brings natural light into the space.

This research focuses on an advanced optical light pipe daylighting system as a means to deliver natural light at the back of deep-plan office buildings (15ft to 30ft), using optimized geometry and high reflective materials. The light pipe configurations follow a previous study at the Lawrence Berkeley National Laboratory (Beltr??n et al., 1997). The current system is designed for College Station, TX (lat: 30?? 36??N), with predominantly mostly sunny sky conditions. This work consists of the monitoring of two scale models simulating a portion of a multi-story office building with open-plan configuration, with interior dimensions 30ft x 20ft x 10ft, built at 1:4 of its real scale, one of the models being the reference case and the other the test case where the light pipe system is placed. The main objectives of this thesis are (a) to examine this daylighting system comparative to the reference case, taking measurements for longer periods than the study at LBNL, as well as to collect detailed data of its performance under different weather conditions and with different materials; (b) to evaluate the visual comfort and possible glare problems of the light pipe system through photographic evaluation and the conduction of a survey that provides people??s opinions and suggestions about the daylighting system. The light pipe system demonstrated a higher performance than the reference case in terms of appropriate levels of light and people??s preferences. The illuminance at the workplane level showed to be adequate with any of the two different diffusing materials used to spread the light into the room. The light pipe without a diffuser was the other condition observed to further understand the bounces of the sunbeam inside the reflective chamber and its consequences on the lighting output. Recommended standards for office spaces with VDT screens together with the analysis of the daylight system, led to preliminary suggestions on how to integrate the light pipe system in an open-plan office configuration. Further study is indicated to reach the complete potential of this advanced optical light pipe that ties illuminance quality with energy savings through the integration of daylight and electric light systems.

We have fabricated a high brightness and color purity white light organic light emitting diode based on a multi-emission-layer. There were several methods to achieve white light OLEDs, including multi-emission- layer device, single emission layer device, and so on. We use RGB triple -emission-layer device to obtain white light, because its EL spectrum is broader than that of the dual-emission-layer device. Frequent problems that showed be faced in a multi-layer structure are the complicate device structure and the color various with different operation voltage. Our work includes five parts. First, we optimized the red light device by controlling the concentration of DCJTB with the configuration of ITO/NPB/Alq3: DCJTB/Alq3/LiF/Al. Second, we optimized the blue light device by controlling the concentration of TC-1753 based on a device structure of ITO/ NPB/ TC-1558: TC-1753/ Alq3/ LiF/ Al. Third, we fabricated green light device by using TPB3 as an emission layer with the configuration of ITO/NPB/TPB3/Alq3/LiF/Al. Then we optimized the dual-emission-layer white light OLED by adjusting the thickness of blue and red emission layers. Finally, we added a green emission layer into the dual emission layer device with the device structure of ITO(1300Å)/NPB(500Å)/ TPB3(500-2xÅ)/ TC-1558(xÅ): TC-1753(2%)/ Alq3(xÅ): DCJTB(2%)/ Alq3(350Å)/ LiF(8Å)/Al(2000Å). By controlling the thickness of each emission layer, a stable white OLED was achieved. The thickness of emission layer were TPB3(200Å)/ TC-1558(150Å):TC-1753(2%)/ Alq3(150Å):DCJTB(2%). The maximum luminance reached 48200 cd/m2 at 13.5V, the maximum current efficiency and power efficiency were 4.06 cd/A at 13V and 1.9 lm/W at 20mA/cm2, respectively. The CIE coordinate varied from (0.339, 0.317) to (0.339, 0.327) with an applied voltage from 9V to 13.5V. We have overcome the problem of instable color purity which was the critical disadvantage of multi-emission-layer white light OLEDs. Our study performed a high brightness and color purity white light device.

Thèse : Sciences physiques : Paris, Faculté des sciences : 1853. / Titre provenant de l'écran-titre.