Throughout the decades, different techniques have been proposed to improve the depth-of-focus in optical microscopy. Common techniques like optical sectioning microscopy and scanning confocal microscopy have innate problems. By simply modifying the pupil function in microscope imaging system, we can also extend the depth-of-focus. The scanning system with a thin annular pupil has a high depth-of-focus and can scan the whole object, but the output light is too dim to be detected well by a photodetector. In this thesis, we propose a scanning technique employing an optical heterodyne scanning system using a difference-of-Gaussians (DoG) pupil. The object is illuminated by the combined beam which consists of two Gaussian beams with different waists, frequencies, and amplitudes. This system does not block most light like the annular pupil system and can obtain high depth-of-focus. The main objective of the thesis is to extend the depth-of-focus using the proposed system. The depth-of-focus characteristics of the DoG pupil function are examined and compared with those of well-known functions such as the circular, annular, and Gaussian pupils. / Master of Science

Overset, or Chimera, meshes are used to discretize the governing equations within a computational domain using multiple meshes that overlap in an arbitrary manner. The overset meshing technique is most applicable to problems dealing with multiple or moving bodies. Deep water simulations were carried out using both single and overset grid techniques for the evaluation of the overset grid application. These simulations were carried out using the commercial CFD code STAR-CCM+ by CD-adapco. The geometry simulated is that of a SES model (T-Craft) tested at the Naval Surface Warfare Center Carderock Division. The craft is simulated with two degrees of freedom, allowing movement in heave and pitch in response to displacement of the free surface. Agreement between the single and overset grid techniques was deemed reasonable to extend to future shallow water cases. However, due to longer run times of the overset mesh, the traditional or single mesh technique should be employed whenever applicable. In order to extend existing full craft CFD simulations of a surface effect ship (SES) into shallow water and maneuvering cases, an overset mesh is needed. Simulations of the SES were performed and monitored at various depth Froude numbers resulting in subcritical, critical, and supercritical flow regimes. Resistance, pitch response, and free surface response of the SES were compared between the shallow water simulations. The SES produced wider wakes, perpendicular to the craft, at simulations closer to the critical flow regime. Critical flow occurs at a depth Froude number between 0.9 and 0.95. Progression of shallow water effects through the three flow regimes agrees well with shallow water theory. / Master of Science

In recent years, the placement of phasor measurement units (PMUs) in electric transmission systems has gained much attention. Engineers and mathematicians have developed a variety of algorithms to determine the best locations for PMU installation. But often these placement algorithms are not practical for real systems and do not cover the whole process. This thesis presents a strategy that is practical and addresses three important topics: system preparation, placement algorithm, and installation scheduling. To be practical, a PMU strategy should strive for full observability, work well within the heterogeneous nature of power system topology, and enable system planners to adapt the strategy to meet their unique needs and system configuration. Practical considerations for the three placement topics are discussed, and a specific strategy based on these considerations is developed and demonstrated on real transmission system models. / Master of Science

Feeding selectivity by the rainbow mussel (Villosa iris) was examined for three age groups; 2-3 days old, 50-53 days old, and 3-6 years old. The mussels were fed an algal diet consisting of Scenedesmus quadricauda (22.3 - 44.5 μm), Nannochloropsis oculata (2.8 – 8.1 μm), and Selenastrum capricornutum (3.6 – 8.5 μm) in equal cell densities. The change in relative abundance of each algal species within feeding chambers over a 5 hr feeding trial was used to discern selectivity. At the conclusion of the feeding trials, the gut contents of mussels were analyzed for preferential ingestion. The mussels selected for N. oculata and S. capricornutum over S. quadricauda (p < 0.05). This may be an indication of particle size-dependent selection. Feeding trials also suggest that selectivity by the rainbow mussel does not change with age. Gut content analyses showed a preferential ingestion of algae, in the sequence N. oculata, S. capricornutum, then S. quadricauda. The suitability of two algal diets, S. quadricauda and N. oculata, for rearing captive juveniles of V. iris in 145-L recirculating culture systems was compared. Juveniles were fed their assigned diet at a density rate of approximately 30,000 cells/ml for 42 days, and sampled weekly for percent survival and shell length. Regardless of diet, juvenile survival decreased rapidly after 21 days, and growth did not exceed approximately 450 μm. High mortality rates and slow growth of juveniles was likely due to inadequate diets. Juveniles that were fed S. quadricauda lacked chlorophyll coloration in their guts, indicating that the juveniles did not ingest this species of algae. Colonies of S. quadricauda were likely too large for the juveniles to ingest. The gut content of juveniles fed N. oculata showed chlorophyll coloration, indicating that the juveniles ingested this species, but N. oculata may have been difficult for the juveniles to assimilate. Under the culture conditions provided, survival and growth did not compare favorably to those of other studies with V. iris. Newly metamorphosed juveniles of V. iris were reared in 145-L recirculating culture systems containing sediment (< 600 μm) of two depths, 5 mm and 15 mm. Mussels were fed a bi-algal diet of Nannochloropsis oculata and Neochloris oleoabundans. Survival differed significantly between treatments (p=0.04), and was higher for juveniles reared in 5 mm of sediment over a 40-day period. Growth was not significantly different between treatments. After 40 days, juveniles achieved a mean length of approximately 578 μm in both treatments. Survival and growth of juveniles compared favorably to those of other culture studies using juveniles of V. iris. A shallow layer of sediment is recommended for the culture of juvenile mussels. / Master of Science

Traditional laser scanning systems, such as those used for microscopy, typically image objects of finite thickness. If the depth-of-focus of such systems is low, as is the case when a simple clear pupil is used, the object must be very thin or the image will be distorted. Several methods have been developed to deal with this problem. A microscope with a thin annular pupil has a very high depth-of-focus and can image the entire thickness of a sample, but most of the laser light is blocked, and the image shows poor contrast and high noise. In confocal laser microscopy, the depth-of-focus problem is eliminated by using a small aperture to discard information from all but one thin plane of the sample. However, such a system requires scanning passes at many different depths to yield an image of the entire thickness of the sample, which is a time-consuming process and is highly sensitive to registration errors. In this thesis, a novel type of scanning system is considered. The sample is simultaneously scanned with a combination of two Gaussian laser beams of different widths and slightly different temporal frequencies. Information from scanning with the two beams is recorded with a photodetector, separated electronically, and processed to form an image. This image is similar to one formed by a system using a difference-of-Gaussians pupil, except no light has been blocked or wasted. Also, the entire sample can be scanned in one pass. The depth-of-focus characteristics of this synthesized difference-of-Gaussians pupil are examined and compared with those of well-known / Master of Science

Yes / Purpose: To determine whether human ocular lens position is influenced by gravity. Methods: Anterior chamber depth and lens thickness were determined with a Haag-Streit Lenstar LS900 for right eyes of participants in two age groups, with a young group of 13 participants aged 18 to 21 years (mean 21 years, SD 1 year) and an older group of 10 participants aged 50 to 63 years (58 years, 4 years). There were two sessions for each participant separated by at least 48 hours, with one session for the usual upright head position and one session for a downwards head position. In a session, testing was done for minimum accommodation followed by testing at maximum accommodation. A drop of 2% pilocarpine nitrate was instilled, and testing was repeated after 30 minutes under minimum and maximum accommodation conditions. Results: Gravity, manipulated through head posture, affected anterior chamber depth for both young adult and older adult groups but mean effects were only small, ranging from 0.04 to 0.12mm, and for the older group required the instillation of an accommodation-stimulating drug. Gravity had a weakly significant effect on lens thickness for the young group without accommodation or a drug, but the effect was small at 0.04±0.06mm (mean±SD, p = 0.04). Conclusion: There is a small but real effect of gravity on crystalline lens position, manifested as reduction in anterior chamber depth at high levels of accommodative effort with the head in a downwards position. This provides evidence of the ability of zonules to slacken during strong accommodation.

Augmented reality provides its user with additional information not available through the natural real-world environment. This additional information displayed to the user potentially poses a risk of perceptual and cognitive load and vision-based difficulties. The presence of real-world objects together with virtual augmenting information requires the user to repeatedly switch eye focus between the two in order to extract information from both environments. Switching eye focus may result in additional time on user tasks and lower task accuracy. Thus, one of the goals of this research was to understand the impact of switching eye focus between real-world and virtual information on user task performance. Secondly, focus depth, which is an important parameter and a depth cue, may affect the user's view of the augmented world. If focus depth is not adjusted properly, it may result in vision-based difficulties and reduce speed, accuracy, and comfort while using an augmented reality display. Thus, the second goal of this thesis was to study the effect of focus depth on task performance in augmented reality systems. In augmented reality environments, real-world and virtual information are found at different distances from the user. To focus at different depths, the user's eye needs to accommodate and converge, which may strain the eye and degrade performance on tasks. However, no research in augmented reality has explored this issue. Hence, the third goal of this thesis was to determine if distance of virtual information from the user impacts task performance. To accomplish these goals, a 3x3x3 within subjects design was used. The experimental task for the study required the user to repeatedly switch eye focus between the virtual text and real-world text. A monocular see-through head- mounted display was used for this research. Results of this study revealed that switching between real-world and virtual information in augmented reality is extremely difficult when information is displayed at optical infinity. Virtual information displayed at optical infinity may be unsuitable for tasks of the nature used in this research. There was no impact of focus depth on user task performance and hence it is preliminarily recommended that manufacturers of head-mounted displays may only need to make fixed focus depth displays; this clearly merits additional intensive research. Further, user task performance was better when focus depth, virtual information, and real-world information were all at the same distance from the user as compared to conditions when they were mismatched. Based on this result we recommend presenting virtual information at the same distance as real-world information of interest. / Master of Science

Yes / Although the depth of reinforced concrete deep beams is much higher than that of slender beams, extensive existing tests on deep beams have focused on simply supported beams with a scaled depth below 600 mm. In the present paper, test results of 12 two-span reinforced concrete deep beams are reported. The main parameters investigated were the beam depth, which is varied from 400 mm to 720 mm, concrete compressive strength and shear span-tooverall depth ratio. All beams had the same longitudinal top and bottom reinforcement and no web reinforcement to assess the effect of changing the beam depth on the shear strength of such beams. All beams tested failed owing to a significant diagonal crack connecting the edges of the load and intermediate support plates. The influence of beam depth on shear strength was more pronounced on continuous deep beams than simple ones and on beams having higher concrete compressive strength. A numerical technique based on the upper bound analysis of the plasticity theory was developed to assess the load capacity of continuous deep beams. The influence of the beam depth was covered by the effectiveness factor of concrete in compression to cater for size effect. Comparisons between the total capacity from the proposed technique and that experimentally measured in the current investigation and elsewhere show good agreement, even though the section depth of beams is varied.

There is a great need in real world applications for estimating depth through electronic means without human intervention. There are many methods in the field which help in autonomously finding depth measurements. Some of which are using LiDAR, Radar, etc. One of the most researched topic in the field of depth measurements is Computer Vision which uses techniques on 2D images to achieve the desired result. Out of the many 3D vision techniques used, stereovision is a field where a lot of research is being done to solve this kind of problem. Human vision plays an important part behind the inspiration and research performed in this field. Stereovision gives a very high spatial resolution of depth estimates which is used for obstacle avoidance, path planning, object recognition, etc. Stereovision makes use of two images in the image pair. These images are taken with two cameras from different views and those two images are processed to get depth information. Processing stereo images has been one of the most intensively sought-after research topics in computer vision. Many factors affect the performance of this approach like computational efficiency, depth discontinuities, lighting changes, correspondence and correlation, electronic noise, etc. An algorithm is proposed which uses texture features obtained using Laws Energy Masks and multi-block approach to perform correspondence matching between stereo pair of images with high baseline. This is followed by forming disparity maps to get the relative depth of pixels in the image. An analysis is also made between this approach to the current state-of-the-art algorithms. A robust method to score and rank the stereo algorithms is also proposed. This approach provides a simple way for researchers to rank the algorithms according to their application needs. / Master of Science / There is a great need in real world applications for estimating depth through electronic means without human intervention. There are many methods in the field which help in autonomously finding depth measurements. Some of which are using LiDAR, Radar, etc. One of the most researched topic in the field of depth measurements is Computer Vision which uses techniques on 2D images to achieve the desired result. Out of the many 3D vision techniques used, stereovision is a field where a lot of research is being done to solve this kind of problem. Human vision plays a important part behind the inspiration and research performed in this field. A large variety of algorithms are being developed to find the measure of depth of ideally each and every point on the pictured scene giving us a very high spatial resolution as compared to other methods. Real world needs of depth estimation and the benefits provided by using stereo vision are the main driving force behind this approach. Stereovision gives a very high spatial resolution which is used for obstacle avoidance, path planning, object recognition, etc. Stereovision makes use of image pairs taken from two cameras with different perspective to estimate depth. The two images in the image pair are taken with two cameras from different views (translational change in view) and those two images are processed to get depth information. The software tool developed is a new approach to perform correspondence matching to find depth using stereo vision concepts. This software tool developed in this work is written in MATLAB. The tools efficiency was evaluated using standard techniques which have been described in detail. The evaluation was also performed by using the software tool with the images collected using a pair of stereo cameras and a tape measure to measure the depth of an object by hand. A scoring method has also been proposed to rank the algorithms in the field of stereo vision.

We present investigation and designing of a system that interacts with big audience, sitting in a dimmed theater environment. The goal is to automatically detect audiences and some of their actions. Test results indicate that because of low light condition we can’t rely on RGB camera footage in a dimmed environment. We use Microsoft Kinect Sensor to collect data from environment. Kinect is designed to be used with Microsoft Xbox 360 for gaming purposes. It has both RGB and Infrared depth camera. Change in amount of visible light doesn’t affect data from depth camera. Kinect is not a strong camera so it has limitations that we should deal with. Viewing angles of both cameras and depth range of Infrared camera are limited. Viewing angles of depth camera are 43° vertical and 57° horizontal. Most accurate range of depth camera is 1 meter to 4 meters from camera. Non-infrared reflective surfaces cause gaps in depth data. We evaluate possibility of using Kinect camera in a large environment with big audience. “Dome 3D theater” in Norrkoping Visualization Center C, is selected as environment to investigate and test the system. We ran some tests to find the best place and best height for camera to have most coverage. Our system works with optimized image processing algorithms that use 3D depth data instead of regular RGB or Grayscale image. We use “libfreenect”, Open Kinect library to get Kinect sensor up and running. C++ and OpenGL are used as programing languages and graphics interface, respectively. Open GLUT (OpenGL Utility Toolkit) is used for system’s user interface. It was not possible to use Dome environment for every test during the programming period so we recorded some depth footage and used for later tests. While evaluating the possibility of using Kinect in Dome environment, we realized that implementing a voting system would make a good demonstration and test application. Our system counts votes after audiences raise their hands to vote for something.