Dissertations / Theses on the topic 'Array based sensing'

Thesis (Ph.D.)--California Institute of Technology, 1999.
"UMI number: 9941121"--T.p. verso. Includes bibliographical references. Also available on microfilm. On-line version available via Caltech Library System.

In this dissertation, sparse processing of signals for directions-of-arrival (DoAs) estimation is addressed in the framework of Compressive Sensing (CS). In particular, DoAs estimation problem for different types of sources, systems, and applications are formulated in the CS paradigm. In addition, the fundamental conditions related to the ``Sparsity'' and ``Linearity'' are carefully exploited in order to apply confidently the CS-based methodologies. Moreover, innovative strategies for various systems and applications are developed, validated numerically, and analyzed extensively for different scenarios including signal to noise ratio (SNR), mutual coupling, and polarization loss. The more realistic data from electromagnetic (EM) simulators are often considered for various analysis to validate the potentialities of the proposed approaches. The performances of the proposed estimators are analyzed in terms of standard root-mean-square error (RMSE) with respect to different degrees-of-freedom (DoFs) of DoAs estimation problem including number of elements, number of signals, and signal properties. The outcomes reported in this thesis suggest that the proposed estimators are computationally efficient (i.e., appropriate for real time estimations), robust (i.e., appropriate for different heterogeneous scenarios), and versatile (i.e., easily adaptable for different systems).

In this dissertation, sparse processing of signals for directions-of-arrival (DoAs) estimation is addressed in the framework of Compressive Sensing (CS). In particular, DoAs estimation problem for different types of sources, systems, and applications are formulated in the CS paradigm. In addition, the fundamental conditions related to the ``Sparsity'' and ``Linearity'' are carefully exploited in order to apply confidently the CS-based methodologies. Moreover, innovative strategies for various systems and applications are developed, validated numerically, and analyzed extensively for different scenarios including signal to noise ratio (SNR), mutual coupling, and polarization loss. The more realistic data from electromagnetic (EM) simulators are often considered for various analysis to validate the potentialities of the proposed approaches. The performances of the proposed estimators are analyzed in terms of standard root-mean-square error (RMSE) with respect to different degrees-of-freedom (DoFs) of DoAs estimation problem including number of elements, number of signals, and signal properties. The outcomes reported in this thesis suggest that the proposed estimators are computationally efficient (i.e., appropriate for real time estimations), robust (i.e., appropriate for different heterogeneous scenarios), and versatile (i.e., easily adaptable for different systems).

The McTronX research group at the North-West University is currently researching self-sensing techniques for Active Magnetic Bearings (AMB). The research is part of an ongoing effort to expand the knowledge base on AMBs in the School of Electrical, Electronic and Computer Engineering to support industries that make use of the technology. The aim of this project is to develop an integrated co-processor based power electronic drive with the emphasis placed on the ability of the co-processor to execute AMB self-sensing algorithms. The two primary techniques for implementing self-sensing in AMBs are state estimation and modulation. This research focuses on hardware development to facilitate the implementation of the modulation method. Self-sensing algorithms require concurrent processing power and speed that are well suited to an architecture that combines a digital signal processor (DSP) and a field programmable gate array (FPGA). A comprehensive review of various power amplifier topologies shows that the pulse width modulation (PWM) switching amplifier is best suited for controlling the voltage and current required to drive the AMB coils. Combining DSPs and power electronics to form an integrated co-processor based power electronic drive requires detail attention to aspects of PCB design, including signal integrity and grounding. A conceptual design is conducted and forms part of the process of compiling a subsystem development specification for the integrated drive, in conjunction with the McTronX Research Group. Component selection criteria, trade-off studies and various circuit simulations serve as the basis for this essential phase of the project. The conceptual design and development specification determines the architecture, functionality and interfaces of the integrated drive. Conceptual designs for the power amplifier, digital controller, electronic supply and mechanical layout of the integrated drive is provided. A detail design is performed for the power amplifier, digital controller and electronic supply. Issues such as component selection, power supply requirements, thermal design, interfacing of the various circuit elements and PCB design are covered in detail. The output of the detail design is a complete set of circuit diagrams for the integrated controller. The integrated drive is interfaced with existing AMB hardware and facilitates the successful implementation of two self-sensing techniques. The hardware performance of the integrated coprocessor based power electronic drive is evaluated by means of measurements taken from this experimental self-sensing setup. The co-processor performance is evaluated in terms of resource usage and execution time and performs satisfactorily in this regard. The integrated co-processor based power electronic drive provided sufficient resources, processing speed and flexibility to accommodate a variety of self-sensing algorithms thus contributing to the research currently underway in the field of AMBs by the McTronX research group at the North-West University.
Thesis (M.Ing. (Electrical Engineering))--North-West University, Potchefstroom Campus, 2009.

Although current head imaging technologies such as magnetic resonance imaging (MRI) and computed tomography (CT) are capable of providing accurate diagnosis of brain injuries such as stroke and brain tumour, they have several limitations including high cost, long scanning time, bulky and mostly stationary. On the other hand, radar-based microwave imaging technology can offer a low cost, non-invasive and non-ionisation method to complement these existing imaging techniques. Moreover, a compact and wearable device for microwave head imaging is required to facilitate frequent or real-time monitoring of a patient by providing more comfort to the patient. Therefore, a wearable head imaging device would be a significant advantage compared to the existing wideband microwave head sensing devices which typically utilise rigid antenna structure. Furthermore, the wearable device can be integrated into different microwave imaging setups such as real-time wearable head imaging systems, portable systems and conventional stationary imaging tools for use in hospitals and clinics. This thesis presents the design and development of wearable devices utilising flexible antenna arrays and compact radio frequency (RF) switching circuits for wideband microwave head imaging applications. The design and characterisation of sensing antennas using flexible materials for the wearable head imaging device are presented in the first stage of this study. There are two main variations of monopole antennas that have been developed in this research, namely trapezoidal and elliptical configurations. The antennas have been fabricated using different flexible substrate materials such as flexible FR-4, polyethylene terephthalate (PET) and textile. Wideband performances of the antennas have been achieved by optimising their co-planar waveguide feeding line structures. Importantly, the efficiencies of the fabricated antennas have been tested using a realistic human head phantom by evaluating their impedance matching performances when operating in close proximity to the head phantom. The second stage of the study presents the development of wearable antenna arrays using the proposed flexible antennas. The first prototype has been built using an array of 12 flexible antennas and a conformal absorbing material backed with a conductive sheet to suppress the back lobe radiation of the monopole antennas. Additionally, the absorber also acts as a mounting base to hold the antennas where the wearable device can be comfortably worn like a hat during the measurement and monitoring processes. The effect of mutual coupling between adjacent antennas in the array has been investigated and optimised. However, the use of the absorbing material makes the device slightly rigid where it can only be fitted on a specific head size. Thus, a second prototype has been developed by using a head band to realise a stretchable configuration that can be mounted on different sizes of human heads. Furthermore, due to the stretchable characteristic of the prototype, the antennas can be firmly held in their positions when measurements are made. In addition, fully textile based sensing antennas are employed in this prototype making it perfectly suitable for monitoring purposes. Low cost and compact switching circuits to provide switching mechanism for the wearable antenna array are presented in the third stage of this study. The switching circuit is integrated with the antenna array to form a novel wearable microwave head imaging device eliminating the use of external bulky switching network. The switching circuit has been built using off-the-shelf components where it can be controlled wirelessly over Bluetooth connection. Then, a new integrated switching circuit prototype has been fabricated using 6-layer printed circuit board (PCB) technology. For the purpose of impedance matching for the radio-frequency (RF) routing lines on the circuit, a wideband Microstrip-to-Microstrip transition is utilised. The final stage of this study investigates the efficacy and sensitivity of the proposed wearable devices by performing experiments on developed realistic human head phantoms. Initially, a human head phantom has been fabricated using food-based ingredients such as tap water, sugar, salt, and agar. Subsequently, lamb's brains have been used to improve the head phantom employed in the experiments to better mimic the heterogeneous human brain. In terms of imaging process, an interpolation technique developed using experimental data has been proposed to assist the localisation of a haemorrhage stroke location using the confocal delay-and-sum algorithm. This new technique is able to provide sensible accuracy of the location of the blood clot inside the brain. The wearable antenna arrays using flexible antennas and their integrations with compact and low cost switching circuits reported in this thesis make valuable contribution to microwave head imaging field. It is expected that a low-cost, compact and wearable radar-based microwave head imaging can be fully realised in the future for wide range of applications including static scanning setup in hospitals, portable equipment in ambulances and as a standalone wearable head monitoring system for remote and real-time monitoring purposes.

The controlled immobilization on a surface of biomolecules used as recognition elements is of fundamental importance in order to realize highly specific and sensible biosensors. Microcantilevers (MC) are nanomechanical sensors, which can be used as label free micro-sized mechanical transducers. MC resonant frequency is sensitively modified upon molecules adsorption, demonstrating an impressive mass resolution. A widely used approach for the immobilization of biorecognition elements on silicon substrates consists in the deposition of 3-aminopropyl-triethoxysilane (APTES) followed by the incubation with glutaraldehyde (GA) as a crosslinking agent. However, these derivatization processes produce a variable chemical functionalization because of the spontaneous polymerization of GA in aqueous solutions. With the aim of producing a more reliable chemical functionalization for protein immobilization, the deposition of a thin film of APTES by self-assembly followed by the modification of its amino groups into carboxyl groups by incubating in succinic anhydride (SA) is proposed. Moreover, the activation of these terminal carboxyl groups were performed by using the EDC/s-NHS protocol in order to enhance their reactivity toward primary amine groups present on biomolecules surface. This method was characterized from a physico-chemical point of view by means of compositional and morphological surface analysis. Moreover, data acquired after the application of this functionalization to a MC-based system showed a highly reproducible deposition of APTES/SA when compared to APTES/GA deposition process. APTES/SA derivatized MC arrays were then incubated with biomolecules for the study of its protein binding capability: the quantification of the grafted biomolecules was performed from the gravimetric data and compared with a theoretical surface density calculated through a molecular modeling tool, providing information about the orientation of the proteins tethered to the surface. In order to avoid or reduce non-specific protein interactions, Bovine Serum Albumin and ethanolamine were considered for their blocking capability. Finally, the detection of the envelope glycoprotein domain III of the Dengue virus type 1 based on immune-specific recognition through the DV32.6 antibody was performed, providing a stoichiometry ratio for the DIII-DV1/DV32.6 interaction. Currently, no cure or vaccine are available; thus, a better understanding of the interactions between the viruses and specific antibodies is expected to provide fundamental information for the development of a vaccine.

Polymerized colloidal crystal arrays (PCCAs) are colloidal crystal arrays that are embedded in a hydrogel matrix. Because they exhibit iridescent colour that can change in response to external stimuli, they have potential to be useful sensing materials. In this research, a new testing platform was synthesized by immobilizing PCCAs on filter paper. This is possible because paper is a porous, hydrophilic, and compliant support. Two methods were developed to optimize these so-called paper-based PCCAs (PB-PCCAs, M. Li, M.Eng. thesis, McGill University). A two-step method involves crystallizing colloidal spheres on paper and then applying a hydrogel to fix the array. Here, the temperature, cast size, dispersion concentration, contact angle of the colloidal dispersion with the mould, and filter paper type all influence the crystallization quality. In a simpler one-step method, PB-PCCAs can be assembled by directly depositing colloidal spheres in pre-gel solution onto paper or gel-filled paper. The one-step method produces much more intense and uniform iridescent colour, and uses significantly less gel and nanoparticles. Both techniques have been optimized to produce superior colour and surface texture than achieved previously, thereby paving the way toward our ultimate goal of developing aptamer functionalized colloidal crystal arrays for molecular- and bio-sensing.
Polymérisés réseaux cristallins colloïdaux (PCCAs) sont des réseaux cristallins colloïdaux qui sont incorporés dans une matrice d'hydrogel. Parce qu'ils présentent une couleur irisée qui peut changer à cause des stimuli externes, ils ont le potentiel d'être utilisé en matériaux de détection. Dans le cadre de cette recherche, une plate-forme de test nouvelle a été synthétisée en immobilisant PCCAs sur un papier filtrant. Ceci est possible parce que le papier est un support poreux hydrophile, et flexible. Deux méthodes ont été développées afin d'optimiser ces soi-disant à base de papier PCCAs (PB-PCCAs, M. Li, M.Eng. Thèse, Université McGill). Procédé en deux étapes est la cristallisation des sphères colloïdales sur papier et puis la application de un hydrogel pour fixer la matrice. Ici, la température, la taille coulée, la concentration en dispersion, l'angle de contact de la dispersion colloïdale sur le moule, et le type de papier filtrant ont tout influence sur la qualité de cristallisation. Dans un simple procédé d'une seule étape, PB-PCCAs peut être assemblé en déposant les sphères colloïdales et le solution de pré-gel sur du papier ou du papier rempli de gel. Cette méthode produit beaucoup plus de couleur intense et uniforme, et utilise beaucoup moins de gel et de nanoparticules. Les deux techniques ont été optimisées pour produire des mieux couleurs et la mieux texture de surface. Cela nous aidera à développer aptamères fonctionnalisés réseaux cristallins colloïdaux pour la molécule de détection enfin.

Le sujet de thèse porte sur des micro/nanorésonateurs ainsi que leurs électroniques de lecture. Les composants mécaniques sont utilisés pour mesurer des masses inférieures à l'attogramme (10-18 g) ou de très faibles concentrations de gaz. Ces composants peuvent ensuite être mis en réseau afin de réaliser des spectromètres de masse ou des détecteurs de gaz. Afin d'atteindre les résolutions nécessaires, il a été choisi d'utiliser une détection harmonique de résonance détectant les variations de la fréquence de résonance d'une nanostructure mécanique. Les dimensions du résonateur sont réduites afin d'augmenter sensibilité en masse, cependant le niveau du signal électrique en sortie du composant est également réduit. Ce faible signal nécessite donc de concevoir de nouvelles transductions électromécaniques ainsi que des architectures électroniques qui minimisent le bruit, les couplages parasites et qui peuvent être mise en réseau
The PhD project focuses on micro or nanomechanical resonators and their surrounding electronics environment. Mechanical components are employed to sense masses in the attogram range (10−18 g) or extremely low gas concentrations. The components can then be implemented in arrays in order to construct cutting-edge mass spectrometers or gas chromatographs. To reach the necessary resolutions, a harmonic detection of resonance technique is employed that measures the shift of the resonant frequency of a tiny mechanical structure due to an added mass or a gas adsorption. The need of shrinking the resonator's dimensions to enhance the sensitivity also reduces the signal delivered by the component. The resonator low output signal requires employing new electromechanical resonator topologies and electronic architectures that minimize the noise, the parasitic couplings and that can be implemented in arrays

In the framework of antenna array synthesis and control, this thesis focus on the development and analysis of techniques based on the Bayesian Compressive Sensing (BCS) for the design of sparse antenna arrays and for the estimation of the direction of arrival (DoA) of signals impinging on an antenna array. After formulating the sparse-array synthesis problem in a probabilistic fashion, the single-task BCS (ST-BCS) is applied to the synthesis of symmetrical antenna arrays with real weights. In order to deal with the synthesis of sparse arrays with complex weights, the multitask version of the BCS (MT-BCS) is employed to correlate the real and imaginary part of the resulting excitation distribution. Concerning the DoA estimation problem, starting from the observation that the signals impinging on the antenna array are sparse in the spatial domain, a single-snapshot ST-BCS -based technique is proposed. Moreover, the MT-BCS -based extension of this technique is introduced in order to enhance the quality of the estimations through the exploitation of the correlation among different snapshots. In the numerical validation, an exhaustive analysis has been performed to assess effectiveness, reliability, but also limitations of the proposed methodologies. Comparisons with state-of-the-art are reported and discussed, as well.

In the framework of antenna array synthesis and control, this thesis focus on the development and analysis of techniques based on the Bayesian Compressive Sensing (BCS) for the design of sparse antenna arrays and for the estimation of the direction of arrival (DoA) of signals impinging on an antenna array. After formulating the sparse-array synthesis problem in a probabilistic fashion, the single-task BCS (ST-BCS) is applied to the synthesis of symmetrical antenna arrays with real weights. In order to deal with the synthesis of sparse arrays with complex weights, the multitask version of the BCS (MT-BCS) is employed to correlate the real and imaginary part of the resulting excitation distribution. Concerning the DoA estimation problem, starting from the observation that the signals impinging on the antenna array are sparse in the spatial domain, a single-snapshot ST-BCS -based technique is proposed. Moreover, the MT-BCS -based extension of this technique is introduced in order to enhance the quality of the estimations through the exploitation of the correlation among different snapshots. In the numerical validation, an exhaustive analysis has been performed to assess effectiveness, reliability, but also limitations of the proposed methodologies. Comparisons with state-of-the-art are reported and discussed, as well.

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Hasler, Paul; Committee Member: Anderson, David; Committee Member: Degertekin, F.; Committee Member: Ghovanloo, Maysam; Committee Member: Minch, Bradley. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Wireless operation, near-field or far-field, is a core functionality of any mobile or autonomous system. These systems are battery operated or most often utilize energy scavenging as a means of power generation. Limited access to power, expected long and uninterrupted operation, and constrained physical parameters (e.g. weight and size), which limit overall power harvesting capabilities, are factors that outline the importance for innovative low-power approaches and designs in advanced low-power wireless applications. Low-power approaches become especially important for the wireless transceiver, the block in charge of wireless/remote functionality of the system, as this block is usually the most power hungry component in an integrated system-on-chip (SoC). Three such advanced applications with stringent power requirements are examined including space-based exploratory remote sensing probes and their associated radiation effects, millimeter-wave phased-array radar for high-altitude tactical and geological imaging, and implantable biomedical devices (IMDs), leading to the proposal and implementation of low-power wireless solutions for these applications in SiGe BiCMOS and CMOS and platforms.

博士
國立臺灣大學
機械工程學研究所
97
This dissertation presents the developments of various types of tactile sensor arrays which will be used as the artificial skins for robot applications. Conductive-polymer-based mechanism and the capacitive mechanism are employed as the sensing techniques. Polyimide (PI) as well as polydimethylsiloxane (PDMS) are used as the substrate materials. For the conductive-polymer-based approach, the tactile sensing elements are formed by dispensing or attaching conductive polymer bumps on the pre-defined electrodes. This novel fabrication method can effectively reduce the crosstalk between each sensing element. Discrete temperature sensor chips are employed as the temperature sensing cells. Also, the temperature and tactile sensing elements are heterogeneously integrated on a flexible substrate using micromachining techniques. Scanning circuits are implemented. Finally, measured temperature and tactile images have been successfully obtained by using the integrated 8×8 and 32×32 sensing arrays. Extendable spiral electrodes, which are highly stretchable and durable, are also designed and fabricated as the row and column interconnects for tactile sensing arrays. The fabricated sensor array can conform to complex surfaces The device can be twisted up to 70 degree without any damage in structure or functionality. For the approach using the capacitive sensing mechanism, tactile sensing arrays are realized by using MEMS fabrication techniques and flexible printed circuit board (FPCB) technologies. The sensing array consists of two micromachined PDMS structures and a flexible FPCB. Each capacitive sensing element comprises two sensing electrodes and a common floating electrode. The sensing electrodes as well as the metal interconnects for signal scanning are implemented on the FPCB, while the floating electrode is patterned on one of the PDMS structures. This special design can effectively reduce the complexity of device structure and thus makes the device highly manufacturable and robust. The characteristics of the devices with different dimensions are measured and discussed. The corresponding scanning circuit is also designed and implemented. The tactile images induced by the PMMA stamps of different shapes are also successfully captured by a fabricated 8×8 array.

碩士
南台科技大學
機械工程系
96
A novel flexible tactile sensor for sensing the incident slippage and its direction were designed by introducing the concept of structural electrodes on a piezoelectric film (PVDF). The structural electrodes consisted of silicone rubber column and distributed microelectrodes between the silicone rubber column and PVDF film. As an object placed upon the silicone rubber column and pushed by an external force, the movement and slippage of object can be detected by the output voltages from the distributed electrodes due to the corresponding stress state under the rubber column. In addition, two opposite output signals from different sides of column can differentiate the direction of slippage as the column was bent by object. The resulting signal for sensing slippage depends on the size of column, weight of object, as observed in the experiments. A larger peak value of signal can be generated for either larger size of column or heavier weight of object due to the more bending moment and normal force, respectively. In general, the flexible tactile sensor can predict not only the occurrence of slippage if the normal force is not only enough but also the direction of object movement, which cannot be achieved by conventional pressure sensor or touch sensor for normal force. Therefore, the sensing technique can be applied to many applications such as handheld devices, smart skin for robot and entertainment devices in the future.

碩士
國立交通大學
光電工程研究所
108
Nowadays, with new technological advances about sensor and VCSEL chip, 3D sensing has gained popular. Owing to small size and high power, 3D sening can be used on mobile device and far distance application. We developed the lens design for different lightsource. In order to improve the divergence angle and uniformity of far field pattern. A uniform and stable light source is easy to design optic lens and develop algorithm. We designed regular micro lens array (MLA)by Lighttools. The MLA can generate uniform far field patern as time of flight (ToF) 3D sensing. After that, we generalized the design flow that based on the multiple combinations of lens profile parameter. According to the design flow, we produced the prototype lens by ultra-precision CNC manufacturing and PMMA injection molding. The divergence angle was 59.07°×73.25° and the uniformity was 90%.

A simple, broadly responsive detector array, based on polymer-carbon black composites that can detect, classify, and quantify various vapors and vapor mixtures is described. The individual detector elements of the array are constructed from films consisting of carbon black particles dispersed into insulating organic polymers. The carbon black provides an electrically conductive network in the films, whereas the different organic polymers are the source of chemical diversity between elements in the detector array. Swelling of the polymer upon exposure to a vapor increases the electrical resistance of the film by disrupting the conductive network of carbon black particles, thereby providing a simple means for monitoring the presence of a vapor. The dc electrical resistance change of an individual composite is shown to be consistent with the predictions of percolation theory. The differing gas-solid partition coefficients between vapor analytes for the various polymers of the detector array produce a characteristic pattern of resistance changes for each analyte. The response of these detectors is linear with variations in analyte concentration, allowing quantification as well as identification of a test analyte. This type of detector array can be used to discriminate different classes of analyte molecules (such as aromatics from alcohols) as well as those within a particular class (such as benzene from toluene and methanol from ethanol). Additionally, by using polymers with chiral subunits, enantiomerically different vapors can be discriminated. Principle component data analysis is used to identify and quantify airborne analytes and the relative compositions of simple gas mixtures. Integration of the electrical resistance signals with data analysis software has made sensing and analysis functions possible in a compact, low-power, simple vapor sensor device.

Pillar-array based optical cavities have unique properties, e.g., having a large and connected low dielectric index space (normally air space), exhibiting a large band gap for transverse magnetic modes, having a large percent of electric field energy in air and standing on a substrate. These properties make them well suitable for applications such as optical sensing and terahertz quantum cascade lasers. However there has been rare research in it due to the common belief that pillar arrays have excessive leakage to the substrate. With careful design, we provided several methods to reduce such a leakage and experimentally proved a high quality factor (Q) pillar-array based cavity is practical. We also explored the usage of such a cavity for optical sensing. Numerical methods such as finite-difference time-domain and plane-wave expansion were used in the design of the cavity. Then in microwave spectrum, cavities consisting of dielectric rods were used to test the validity of the theory. Additionally, we observed that a high-Q cavity for modes above light line is feasible and it is very suitable to measure the optical absorption of materials introduce inside the mode volume. Finally in the optical domain, pillar arrays were fabricated in Si/SiO2 material system and measured. Q as high as 27,600 was shown and when applying accurate refractive indices, for every delta n = 0.01, the peak wavelength shifted as large as 3.5 nm, testifying the ultra sensitivity of the cavity to the environmental dielectric change.

In the past decade, camera manufacturers have offered smaller form factors, smaller pixel sizes (leading to higher resolution images), and faster processing chips to increase the performance of consumer cameras. However, these conventional approaches have failed to capitalize on the spatio-temporal redundancy inherent in images, nor have they adequately provided a solution for finding $3$D point correspondences for cameras sampling different bands of the visible spectrum. In this thesis, we pose the following question---given the repetitious nature of image patches, and appropriate camera architectures, can statistical models be used to increase temporal, structural, or spectral resolution? While many techniques have been suggested to tackle individual aspects of this question, the proposed solutions either require prohibitively expensive hardware modifications and/or require overly simplistic assumptions about the geometry of the scene. We propose a two-stage solution to facilitate image reconstruction; 1) design a linear camera system that optically encodes scene information and 2) recover full scene information using prior models learned from statistics of natural images. By leveraging the tendency of small regions to repeat throughout an image or video, we are able to learn prior models from patches pulled from exemplar images. The quality of this approach will be demonstrated for two application domains, using low-speed video cameras for high-speed video acquisition and multi-spectral fusion using an array of cameras. We also investigate a conventional approach for finding 3D correspondence that enables a generalized assorted array of cameras to operate in multiple modalities, including multi-spectral, high dynamic range, and polarization imaging of dynamic scenes.

This thesis presents the development of a Sensor Tower Platform (STP) comprised of an array of Passive Infra-Red (PIR) sensors along with a classification algorithm that enables the STP to distinguish between human intrusion, animal intrusion and clutter arising from wind-blown vegetative movement in an outdoor environment. The research was motivated by the aim of exploring the potential use of wireless sensor networks (WSNs) as an early-warning system to help mitigate human-wildlife conflicts occurring at the edge of a forest. While PIR sensors are in commonplace use in indoor settings, their use in an outdoor environment is hampered by the fact that they are prone to false alarms arising from wind-blown vegetation. Every PIR sensor is made up of one or more pairs of pyroelectric pixels arranged in a plane, and the orientation of interest in this thesis is one in which this plane is a vertical plane, i.e., a plane perpendicular to the ground plane. The intersection of the Field Of View (FOV) of the PIR sensor with a second vertical plane that lies within the FOV of the PIR sensor, is called the virtual pixel array (VPA). The structure of the VPA corresponding to the plane along which intruder motion takes place determines the form of the signal generated by the PIR sensor. The STP developed in this thesis employs an array of PIR sensors designed so as to result in a VPA that makes it easier to discriminate between human and animal intrusion while keeping to a small level false alarms arising from vegetative motion. The design was carried out in iterative fashion, with each successive iteration separated by a lengthy testing phase. There were a total of 5 design iterations spanning a total period of 14 months. Given the inherent challenges involved in gathering data corresponding to animal intrusion, the testing of the SP was carried out both using real-world data and through simulation. Simulation was carried out by developing a tool that employed animation software to simulate intruder and animal motion as well as some limited models of wind-blown vegetation. More specifically, the simulation tool employed 3-dimensional models of intruder and shrub motion that were developed using the popular animation software Blender. The simulated output signal of the PIR sensor was then generated by calculating the area of the 3-dimensional intruder when projected onto the VPA of the STP. An algorithm for efficiently calculating this to a good degree of approximation was implemented in Open Graphics Library (OpenGL). The simulation tool was useful both for evaluating various competing design alternatives as well as for developing an intuition for the kind of signals the SP would generate without the need for time-consuming and challenging animal-motion data collection. Real-world data corresponding to human motion was gathered on the campus of the Indian Institute of Science (IISc), while animal data was recorded at a dog-trainer facility in Kengeri as well as the Bannerghatta Biological Park, both located in the outskirts of Bengaluru. The array of PIR sensors was designed so as to result in a VPA that had good spatial resolution. The spatial resolution capabilities of the STP permitted distinguishing between human and animal motion with good accuracy based on low-complexity, signal-energy computations. Rejecting false alarms arising from vegetative movement proved to be more challenging. While the inherent spatial resolution of the STP was very helpful, an alternative approach turned out to have much higher accuracy, although it is computationally more intensive. Under this approach, the intruder signal, either human or animal, was modelled as a chirp waveform. When the intruder moves along a circular arc surrounding the STP, the resulting signal is periodic with constant frequency. However, when the intruder moves along a more likely straight-line path, the resultant signal has a strong chirp component. Clutter signals arising from vegetative motion does not exhibit this chirp behavior and an algorithm that exploited this difference turned in a classification accuracy in excess of 97%.