Selective Darkening Filter and Welding Arc Observation for the Manual Welding Process

An optical see-through LCD (GLCD) with a resolution of n x m pixels gives the ability to selectively control the darkening in the welders view. The setup of such a Selective Auto Darkening Filter is developed and its applicability tested. The setup is done by integrating a camera into the welding operation for extracting the welding arc position properly. A prototype of a GLCD taylored for welding is mounted in the welder's view. The extraction of the welding arc position requires an enhanced video acquisition during welding. The observation of scenes with high dynamic contrast is an outstanding problem which occurs if very high differences between the darkest and the brightest spot in a scene occur. The application to welding with its harsh conditions needs the development of supporting hardware. The synchronization of the camera with the flickering light conditions of pulsed welding processes in Gas Metal Arc Welding (GMAW) stabilizes the acquisition process and allows the scene to be flashed precisely if required by compact high power LEDs. The image acquisition is enhanced by merging two different exposed images for the resulting image. These source images cover a wider histogram range than it is possible by using only a single shot image with optimal camera parameters. After testing different standard contrast enhancement algorithm a novel content based algorithm is developed. It segments the image into areas with similar content and enhances these independently

Demonstration test of burner liner strain measuring system

A demonstration test was conducted for two systems of static strain measurement that had been shown to have potential for application jet engine combustors. A modified JT12D combustor was operated in a jet burner test stand while subjected simultaneously to both systems of instrumentation, i.e., Kanthal A-1 wire strain gages and laser speckle photography. A section of the burner was removed for installation and calibration of the wire gages, and welded back into the burner. The burner test rig was modified to provide a viewing port for the laser speckle photography such that the instrumented section could be observed during operation. Six out of ten wire gages survived testing and showed excellent repeatability. The extensive precalibration procedures were shown to be effective in compensating for the large apparent strains associated with these gages. Although all portions of the speckle photography system operated satisfactorily, a problem was encountered in the form of optical inhomogeneities in the hot, high-pressure gas flowing by the combustor case which generate large and random apparent strain distributions

A New electronic image array: The Active pixel charge injection device

This is a Ph.D. thesis dissertation in which a new type of image sensor is investigated as possible successor to the charge coupled device (CCD) for scientific applications. As a result of the work described in this dissertation, the active pixel charge injection device (AP-CID) has been developed. This device retains most of the positive features of both the charge injection device (CJD) imager (random readout, non destructive readout, antiblooming, increased UV sensitivity, radiation tolerance, low power consumption, low manufacturing price) and the CCD imager (low noise, high dynamic range). The device lacks most of the drawbacks of the aforementioned devices. A functional array architecture was created. Based on this architecture several devices were fabricated. One of the arrays was fully measured, characterized and suggestions for improvement were formulated. Most of the characterizationalysis work described in this dissertation was centered on the following issues: temporal noise, linearity and FPN. The measured noise performance of the new device is excellent and comparable to the noise performance of the scientific CCD. The newly developed sensor is necessary for scientific imaging applications in space based operation. However due to its qualities, this device could be used in a much wider range of applications including commercial digital cameras, spectroscopy, biological, nuclear and other scientific applications

Kinematic Analysis of the Chemotactic Locomotion of Human Blood Neutrophils: The Effects of Storage at Room Temperature

When human blood neutrophils are isolated for the circulation, they begin to lose chemotactic responsiveness. To characterize this loss of function which occurs during storage, an enhanced videomicroscope system was developed and computer-assisted image analysis was utilized to perform kinematic analysis on neutrophils migrating in an agarose assay system. The locomotor behavior of neutrophils was measured in response to a gradient of chemoattractant (chemotaxis) and in response to an isotropic distribution of chemoattractant (chemokinesis). During chemotaxis, neutrophils migrate at ~20 um/min, make few turns and orient toward a chemoattractant with high accuracy and precision. During chemokinesis, neutrophils migrate at a slower speed, change direction more often and show no directional preference. The vast majority of normal, fresh neutrophils show chemotaxis in response to a gradient, while ~10% of fresh normal cell fail to orient in a gradient. After storage, ~65% of the cells show normal chemotaxis in response to a gradient. The other 35% migrate at 8-9um/min and show no directional preference; they orient randomly. This behavior is quantitatively similar to chemokinesis and suggests that such cells either cannot detect the gradient or cannot respond to the gradient. A model is proposed which suggests that the ability to orient accurately in a gradient is a function of a structural asymetry within the cytoskeleton and that the loss of this unique structural arrangement by some cells during storage produces slower I non-oriented “chemokinetic” locomotion in response to a gradient

Serial laser lithography for efficient manufacture of universal microstructures

The technique of microstructuring revolutionises all classical fields of engineering like electronics, optics and mechanics. In order to manufacture a microstructure in large quantities and at a reasonable price, master elements or masks will be formed that can be duplicated in a highly efficient process. Further development in technology leads, on the one hand, to further reduction of possible dimensions of structures down to the range of sub-nano technology and, on the other hand, to the development of more flexible systems in using more reasonably priced technologies for the structuring in the classical micrometre range, which in turn opens a much larger field of use. This study examines the use of serial laser lithography for efficient manufacture of universal microstructures. To facilitate this, a laser beam writer or so-called Laser Pattern Generator (LPG) was developed and described here as well as in a previous work[Samu96a]. The laser beam writer uses a precise positioning system for the movement of a substrate for material processing using a focussed laser beam. This system permits the production of structures with dimensions down to 0.5 μm which can be used in several application fields. This was systematically analysed for optimisation of the production process. Based on the achieved results, a computer-aided simulation system for process parameter determination and optimisation was developed that may be used in order to minimise the experimental effort in LPG manufacturing. The total production process and the individual optimising steps are illustrated by the manufacture of different microstructures. Because of the high reproducibility in manufacturing different structure types and, compared with other manufacturing methods, the low equipment and manufacturing effort, serial laser lithography is an efficient process for the microstructuring of universal microstructures down to the dimensions in the micrometre range

Imaging of the Vulnerable Atherosclerotic Plaque. Pre-Clinical Evaluation of PET Tracers for Vascular Inflammation

Atherosclerosis is a vascular inflammatory disease causing coronary artery disease, myocardial infarct and stroke, the leading causes of death in Finland and in many other countries. The development of atherosclerotic plaques starts already in childhood and is an ongoing process throughout life. Rupture of a plaque and the following occlusion of the vessel is the main reason for myocardial infarct and stroke, but despite extensive research, the prediction of rupture remains a major clinical problem. Inflammation is considered a key factor in the vulnerability of plaques to rupture. Measuring the inflammation in plaques non-invasively is one potential approach for identification of vulnerable plaques. The aim of this study was to evaluate tracers for positron emission tomography (PET) imaging of vascular inflammation. The studies were performed with a mouse model of atherosclerosis by using ex vivo biodistribution, autoradiography and in vivo PET and computed tomography (CT). Several tracers for inflammation activity were tested and compared with the morphology of the plaques. Inflammation in the atherosclerotic plaques was evaluated as expression of active macrophages. Systematic analysis revealed that the uptake of 18F-FDG and 11C-choline, tracers for metabolic activity in inflammatory cells, was more prominent in the atherosclerotic plaques than in the surrounding healthy vessel wall. The tracer for αvβ3 integrin, 18Fgalacto- RGD, was also found to have high potential for imaging inflammation in the plaques. While 11C-PK11195, a tracer targeted to receptors in active macrophages, was shown to accumulate in active plaques, the target-to-background ratio was not found to be ideal for in vivo imaging purposes. In conclusion, tracers for the imaging of inflammation in atherosclerotic plaques can be tested in experimental pre-clinical settings to select potential imaging agents for further clinical testing. 18F-FDG, 18F-galacto-RGD and 11C-choline choline have good properties, and further studies to clarify their applicability for atherosclerosis imaging in humans are warranted.Siirretty Doriast

Readout and Control Beyond a Few Qubits: Scaling-up Solid State Quantum Systems

Quantum entanglement and superposition, in addition to revealing interesting physics in their own right, can be harnessed as computational resources in a machine, enabling a range of algorithms for classically intractable problems. In recent years, experiments with small numbers of qubits have been demonstrated in a range of solid-state systems, but this is far from the numbers required to realise a useful quantum computer. In addition to the qubits themselves, quantum operation requires a host of classical electronics for control and readout, and current techniques used in few-qubit systems are not scalable. This thesis presents a series of techniques for control and readout of solid-state qubits, working towards scalability by integrating classical control with the quantum technology. Two techniques for reducing the footprint associated with readout of gallium arsenide spin qubits are demonstrated. Gate electrodes, used to define the quantum dot, are also shown to be sensitive state detectors. These gate-sensors, and the more conventional Quantum Point Contacts, are then multiplexed in the frequency domain, where three-channel qubit readout and ten-channel QPC readout are demonstrated. Two types of superconducting devices are also explored. The loss in superconducting coplanar waveguide resonators is measured, and a suppression of coupling to the parasitic electromagnetic environment is demonstrated. The thesis also details software for the simulation of Josephson-junction based circuits including features beyond what is available in commercial products. Finally, an architecture for managing control of a scalable machine is proposed where classical components are distributed throughout a cryostat and cryogenic switches route control pulses to the appropriate qubits. A simple implementation of the architecture is demonstrated that incorporates a double quantum dot, a gallium arsenide switch matrix, frequency multiplexed readout, and cryogenic classical computation

Mink of the Rochester Embayment of Lake Ontario: Population Monitoring; Age, Size, and Stable Isotope Analysis; and a Predictive Model for Bioaccumulation of Chemicals of Concern

My studies were part of a project to determine whether mink populations are negatively impacted by pollution in Lake Ontario, especially in the Rochester Embayment Area of Concern (AOC). My first study used video traps to monitor mink activity as a surrogate for mink abundance, with video traps placed in four regions: AOC: In/Inland, AOC: In/Lakeshore, AOC: Out/Inland, and AOC: Out/Lakeshore. My MustelaVision data tentatively suggest that there may be differences in abundances in mink populations inside and outside the AOC, and between the lakeshore and inland areas, but my analysis was unable to assign significance to those differences. The statistical power of my tests was low due to small sample sizes and large variability in the data, and the test was further confounded by the fact that landscape-scale features (wetland complexes) and microhabitat factors (tunnels) are key predictors of mink presence or absence at a sampling site. I also showed that mink are reproducing in the AOC, and that mink are not chiefly nocturnal. My second study used age and stable isotope data taken from mink carcasses to compare populations among the four regions, and to create a model to predict exposure levels of mink to bioaccumulative chemicals of concern (BCCs ). The Regional Descriptors (AOC: In vs. Out, Lakeshore vs. Inland, Wetland vs. Mixed habitat) had no significant effect on the ages of mink trapped, but mean ages were depressed in areas previously trapped. Mink less than one year old were trapped in each area, suggesting reproduction in all areas. δ15N values indicated that mink in the study area feed on prey at trophic level 2.5 (slightly higher along the lakeshore and in the AOC than elsewhere), with the highest level (2.8) in the Braddock Bay Wildlife Management Area. Using known concentrations of selected BCCs in Lake Ontario and trophic level calculations based on stable isotope analyses, I created a food web bioaccumulation model to predict the exposure of mink in the AOC to those BCCs

Quantitative and automatic analysis of interferometric fringe data using carrier fringe and FFT techniques

Computerised analysis of optical fringe pattern is a rapidly developing approach to extract quantitative data from phase encoded intensity distribution. This thesis describes results of investigations of quantitative and automatic analysis of interference fringe data using carrier fringe and FFT techniques. Several automatic and semiautomatic fringe analysis algorithms that enable the reduction of fringe patterns to quantitative data have been reviewed and illustrated with some examples. A fresh holographic contouring approach by the movement of object beams through fibre optics is described. The use of fibre optics provides a simple method for obtaining contouring fringes in the holographic system. A carrier fringe technique for measuring surface deformation is described and verified by experiments. A theoretical analysis of the carrier fringe technique is given. The effects of carrier frequency on holographic fringe data has been investigated with computer generated holograms. In contrast to conventional holography and fringe analysis, this holographic system based on fibre optics and automatic spatial carrier fringe analysis technique. The FFT approach is used to process the interferograms. An excellent correlation between the theoretical deformation profile and that suggested by the technique is given. The accuracy of the measurement for a centrally loaded aluminum disk is 0.05pm. The design and construction of a computerised photoelastic stress measurement system is discussed. This full field, fully automated photoelastic stress measurement system is a new approach to photoelastic fringe analysis. Linear carrier fringes generated using quartz wedge are superimposed on fringes formed by the stressed model. The resultant fringes pattern is then captured using a CCD camera and stored in a digital frame buffer. A FFT method has been used to process the complete photoelastic fringe image over the whole surface of the model. The whole principal stress difference field has been calculated and plotted from one single video frame