<p>Denna uppsats syftar till att undersöka användbarheten av metoden Independent Component Analysis (ICA) för brusreducering av bilder tagna av infraröda kameror. Speciellt fokus ligger på att reducera additivt brus. Bruset delas upp i två delar, det Gaussiska bruset samt det sensorspecifika mönsterbruset. För att reducera det Gaussiska bruset används en populär metod kallad sparse code shrinkage som bygger på ICA. En ny metod, även den byggandes på ICA, utvecklas för att reducera mönsterbrus. För varje sensor utförs, i den nya metoden, en analys av bilddata för att manuellt identifiera typiska mönsterbruskomponenter. Dessa komponenter används därefter för att reducera mönsterbruset i bilder tagna av den aktuella sensorn. Det visas att metoderna ger goda resultat på infraröda bilder. Algoritmerna testas både på syntetiska såväl som på verkliga bilder och resultat presenteras och jämförs med andra algoritmer.</p> / <p>The purpose of this thesis is to evaluate the applicability of the method Independent Component Analysis (ICA) for noise reduction of infrared images. The focus lies on reducing the additive uncorrelated noise and the sensor specific additive Fixed Pattern Noise (FPN). The well known method sparse code shrinkage, in combination with ICA, is applied to reduce the uncorrelated noise degrading infrared images. The result is compared to an adaptive Wiener filter. A novel method, also based on ICA, for reducing FPN is developed. An independent component analysis is made on images from an infrared sensor and typical fixed pattern noise components are manually identified. The identified components are used to fast and effectively reduce the FPN in images taken by the specific sensor. It is shown that both the FPN reduction algorithm and the sparse code shrinkage method work well for infrared images. The algorithms are tested on synthetic as well as on real images and the performance is measured.</p>

Denna uppsats syftar till att undersöka användbarheten av metoden Independent Component Analysis (ICA) för brusreducering av bilder tagna av infraröda kameror. Speciellt fokus ligger på att reducera additivt brus. Bruset delas upp i två delar, det Gaussiska bruset samt det sensorspecifika mönsterbruset. För att reducera det Gaussiska bruset används en populär metod kallad sparse code shrinkage som bygger på ICA. En ny metod, även den byggandes på ICA, utvecklas för att reducera mönsterbrus. För varje sensor utförs, i den nya metoden, en analys av bilddata för att manuellt identifiera typiska mönsterbruskomponenter. Dessa komponenter används därefter för att reducera mönsterbruset i bilder tagna av den aktuella sensorn. Det visas att metoderna ger goda resultat på infraröda bilder. Algoritmerna testas både på syntetiska såväl som på verkliga bilder och resultat presenteras och jämförs med andra algoritmer. / The purpose of this thesis is to evaluate the applicability of the method Independent Component Analysis (ICA) for noise reduction of infrared images. The focus lies on reducing the additive uncorrelated noise and the sensor specific additive Fixed Pattern Noise (FPN). The well known method sparse code shrinkage, in combination with ICA, is applied to reduce the uncorrelated noise degrading infrared images. The result is compared to an adaptive Wiener filter. A novel method, also based on ICA, for reducing FPN is developed. An independent component analysis is made on images from an infrared sensor and typical fixed pattern noise components are manually identified. The identified components are used to fast and effectively reduce the FPN in images taken by the specific sensor. It is shown that both the FPN reduction algorithm and the sparse code shrinkage method work well for infrared images. The algorithms are tested on synthetic as well as on real images and the performance is measured.

The purpose of this project was to create an active dampening suspension for a small prototype that was able to detect obstacles using infrared sensors. The suspension system consisted of servomotors that controlled the angle of a leg upon which a wheel was attached. The infrared distance sensor measured the height of obstacles and the necessary raising of the suspension was calculated on a microcomputer of type Arduino Uno. It was concluded that the constructed system of suspension and obstacle detection was inadequate. Most subsystems worked but not as a whole. / Syftet med detta projekt var att konstruera en aktiv stötdämpning för en mindre prototyp som skulle upptäcka hinder med hjälp av infraröda sensorer. Upphängningen bestod av servomotorer som styrde vinkeln på benen där hjulen var monterade. De infraröda sensorerna mätte höjden på hindren och hur mycket upphängningen skulle lyftas beräknades sedan med en mikrodator av typen Arduino Uno. Slutsatsen blev att det konstruerade system av upphängning och hinder-detektion var otillräckligt. De flesta delsystemen fungerade men inte helheten.

Minimally Invasive Surgery (MIS) differs from Open Surgery as surgeons view the surgical site indirectly on a monitor. The view shown is typically from an angled endoscope off to one side of the surgery (i.e., uncollocated with the view of the hands). This makes camera navigation a challenging ability to learn. MIS thus requires longer training periods, more practice and mental effort to achieve proficiency. Current training setups and Operating Room (OR) environments lack appropriate real-time visual cues for navigation and other perception related information that could help with learning and performance in the OR. The purpose of this research was to design and develop graphical aids for improving understanding of camera navigation and depth perception in a trainer box necessary for enhancing surgeon’s skills to perform endoscopic surgery. For the former, two alternate training methods: 1) using no graphics (control group) and 2) using three different types of graphics conveying different information, were considered for this study. The effectiveness of the training was evaluated by a comparative analysis of different performance measures across all the groups. It was observed that training using graphics did improve the performance of participants in performing a minimally invasive surgery training task. For the latter, the use of a proximity sensor was explored.

The presented work describes first principles for monitoring gas hydrate formation and dissociation in solution by evaluating state-responsive IR absorption features of water with fiberoptic evanescent field spectroscopy. In addition, a first order linear functional relationship has been derived according to Lambert Beer’s law, which enables quantification of percentage gas hydrate within the volume of water directly probed via the evanescent field. Moreover, spectroscopic studies evaluating seafloor sediments collected from a gas hydrate site in the Gulf of Mexico revealed minimal spectral interferences from sediment matrix components, thereby establishing evanescent field sensing strategies as a promising perspective for monitoring the dynamics of gas hydrates in oceanic environments.

Substantial amounts of methane are sequestered in naturally occurring ice-like formations known as gas hydrates. In particular, oceanic gas hydrates are globally distributed in complex heterogeneous ecosystems that typically occur at depths exceeding 300 m. Gas hydrates have received attention for their potential as an alternative energy resource, as marine geohazards, and their role in cycling of greenhouse gases. In addition, chemosynthetic communities often play a vital role in the cycling and sequestration of carbon emanating from cold hydrocarbon seeps surrounding hydrate sites. Research efforts are presently striving to better understand the significance and complexity of these ecosystems through the establishment of seafloor observatories capable of long-term monitoring with integrated sensor networks. In this thesis, infrared (IR) spectroscopy has been implemented for the investigation of molecular-specific signatures to monitor gas hydrate growth dynamics and evaluate carbonate minerals, which are intimately connected with complex chemosynthetic processes occurring in these harsh environments. The first fundamental principles and data evaluation strategies for monitoring and quantifying gas hydrate growth dynamics utilizing mid-infrared (MIR) fiber-optic evanescent field spectroscopy have been established by exploiting the state-responsive IR absorption behavior of water. This has been achieved by peak area evaluation of the O-H stretch, H-O-H bend, and libration modes and assessing peak shifts in the 3rd libration overtone and libration bands during the formation and dissociation of simple clathrate hydrates of methane, ethane, and propane formed from aqueous solution. Hydrate growth and monitoring was facilitated with a customized pressure cell enabling operation up to ~5.9 MPa with spectroscopic, temperature, pressure, and video monitoring capabilities. Furthermore, the initial feasibility for extending the developed IR spectroscopic hydrate monitoring strategies into oceanic gas hydrate ecosystems has been demonstrated through the evaluation of potential spectroscopic interferences from sediment matrices in samples collected from two hydrate sites in the Gulf of Mexico (GoM). With exception of the libration band, the primary IR absorption features of water are readily accessed within hydrated sediment samples. Additional consideration for potential long-term hydrate monitoring applications revealed that the collection of approx. 2 IR spectra per day should enable direct insight into the temporal dynamics of hydrates...

Approved for public release; distribution in unlimited. / Silicon Blocked Impurity Band (BIB) detectors are highly efficient, radiation-hardened photodetectors that operate in the range of 5-40 æm. To further extend BIB coverage to 40-350 æm, Ge and GaAs BIB detectors are under development; however, these new detectors face fabrication issues that have delayed their introduction. This thesis will describe the use of a numerical model to examine alternate operating modes for GaAs BIB detectors in order to bypass current fabrication issues. The numerical simulations provide an understanding of the fundamental physics that governs detector transport. The proposed alternatives to standard operation are created by reversing the detector's bias and varying the blocking layer thickness. Modeling indicates that reversing the bias on these detectors provides a larger signal current than standard configurations, while preserving the principal benefits gained from a multilayered device. At the same time, the alternate bias configuration allows for the use of thicker blocking layers, while preserving overall detector responsivity and reducing shot noise. This proposed new model of operation should allow for the relaxation of fabrication constraints without sacrificing the inherent benefits associated with BIB detectors. These devices are of potential interest for missile defense and terahertz surveillance applications. / Lieutenant Commander, United States Navy

The field of infrared (IR) detector technology has shown vast improvements in terms of speed and performance over the years. Specifically the dynamic range (DR) and sensitivity of detectors showed significant improvements. The most commonly used technique of implementing these IR detectors is the use of charge-coupled devices (CCD). Recent developments show that the newly investigated bipolar complementary metal-oxide semiconductor (BiCMOS) devices in the field of detector technology are capable of producing similar quality detectors at a fraction of the cost. Prototyping is usually performed on low-cost silicon wafers. The band gap energy of silicon is 1.17 eV, which is too large for an electron to be released when radiation is received in the IR band. This means that silicon is not a viable material for detection in the IR band. Germanium exhibits a band gap energy of 0.66 eV, which makes it a better material for IR detection. This research is aimed at improving DR and sensitivity in IR detectors. CCD technology has shown that it exhibits good DR and sensitivity in the IR band. CMOS technology exhibits a reduction in prototyping cost which, together with electronic design automation software, makes this an avenue for IR detector prototyping. The focus of this research is firstly on understanding the theory behind the functionality and performance of IR detectors. Secondly, associated with this, is determining whether the performance of IR detectors can be improved by using silicon germanium (SiGe) BiCMOS technology instead of the CCD technology most commonly used. The Simulation Program with Integrated Circuit Emphasis (SPICE) was used to realise the IR detector in software. Four detectors were designed and prototyped using the 0.35 µm SiGe BiCMOS technology from ams AG as part of the experimental verification of the formulated hypothesis. Two different pixel structures were used in the four detectors, which is the silicon-only p-i-n diodes commonly found in literature and diode-connected SiGe heterojunction bipolar transistors (HBTs). These two categories can be subdivided into two more categories, which are the single-pixel-single-amplifier detectors and the multiple-pixel-single-amplifier detector. These were needed to assess the noise performance of different topologies. Noise influences both the DR and sensitivity of the detector. The results show a unique shift of the detecting band typically seen for silicon detectors to the IR band, accomplished by using the doping feature of HBTs using germanium. The shift in detecting band is from a peak of 250 nm to 665 nm. The detector still accumulates radiation in the visible band, but a significant portion of the near-IR band is also detected. This can be attributed to the reduced band gap energy that silicon with doped germanium exhibits. This, however, is not the optimum structure for IR detection. Future work that can be done based on this work is that the pixel structure can be optimised to move the detecting band even more into the IR region, and not just partially. / Dissertation (MEng)--University of Pretoria, 2013. / Electrical, Electronic and Computer Engineering / unrestricted