The area of fault-handling in reconfigurable logic devices is one that continues to receive research attention in the field of engineering. Field Programmable Gate Arrays (FPGAs) are reconfigurable logic devices that have become an essential element in electronic hardware used for space applications, for instance deep space satellites. When electronic devices such as FPGAs are launched into space, they are relentlessly exposed to fault-inducing hazards such as high levels of radiation and extreme temperatures. The ability of the device to maintain and correct its functionality while experiencing these harsh conditions is vital to a successful mission by today's technological standards. Many techniques have been proposed for the purpose of detecting and repairing hardware faults that occur in reconfigurable logic devices. The implementation of a Genetic Algorithm (GA) as the means of repairing a faulty component has become a popular method among such techniques. A great deal of success has been demonstrated by the use of GAs in fault-repair, but there is room for improvement in the completeness of a given repair. This thesis addresses this issue by exploring the possible outcomes of implementing a voting system to work in parallel with a particular GA. Throughout the first two chapters, a general overview ofFPGAs and faulthandling techniques is provided. The advantages and disadvantages of each technique are mentioned to help re-emphasize the main purpose for the research being conducted. Once a solid background has been established regarding the main ideas behind this work, the thesis presents an in-depth description of the problem and the experimental approach that is taken. The work involves experiments which are run using a simulated FPGA that is coded in C++. A genetic algorithm is included in the program in order to simulate the repair process. By varying the parameters of the GA, as well as experimenting with the addition of a voting scheme to enhance the performance, meaningful results are discovered and presented. Fault-handling techniques proposed in the future will have a better idea of whether or not it would be beneficial to include a voting scheme to improve success.

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / Two retrodirective antenna systems that autonomously point high gain beams to a signal source without requiring a priori knowledge of location are described. The first is a stationary phased array requiring no phase shifters or switches for its operation. The second is a steerable platform with a thinned receive array for signal acquisition and platform pointing and dish(es) to satisfy the high gain function.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Employment of the retro-directive technique described in Reference 1 describes a totally Autonomous Ground Station providing hemispheric coverage and continuous tracking. This System establishes communications between the satellite and ground station without human intervention or moving parts. When a satellite is in view, the ground station beacon antenna, using CDMA, enables the desired satellite transmitter and directs its beam to the ground station. The ground station, using the satellite’s transmitted signal, directs it’s receive and transmit arrays to point the ground station beams to the satellite, establishing two-way communications. The process is automatic and provides continuous horizon to horizon tracking.

During the synthesis of well arrayed nano/micro structures through wet chemical methods, plenty of parameters are usually involved. Consequently, it is extremely time- and cost-consuming to find out the optimized synthesis conditions by using the conventional "changing one separate factor at a time" (COST) strategy. Instead, the "statistical experimental design" method has been proven in a few works to be an efficient method for experiments involving many parameters.  With this method, the responses could be optimized efficiently by using only a few experiments. Besides, several responses can be optimized simultaneously. Also, models could be built up and the changing tendency can be plotted to predict the required experimental settings for specific tasks. Two types of well arrayed structures including monolayer arrays of silica spheres and vertically aligned ZnO rod arrays were investigated in this work. Monolayer arrays of silica spheres were synthesized by using a dual-speed spin coating method. With assistance of statistical experimental design, the accelerating rate, the second rotation speed and time of the dual-speed spin coating system were found as non-significant parameters to the ordering degree of the obtained monolayer, and thus they can be fixed. This finding could remarkably increase the feasibility of optimizing the practical process. On the other hand, the relative humidity, the first rotation speed and the suspension concentration are identified as the significant parameters to the structures of the monolayer. Moreover, the optimal values for these three parameters were identified: 23% for the relative humidity, 1000 rpm for the first rotation speed and 30 wt.% for the suspension concentration. With these optimized parameters, the area of the obtained silica sphere monolayers reached over 1 cm2 and the defect-free domain size reached over 4000 μm2. These values are considerably higher compared to the previously reported values. Vertically aligned ZnO rod arrays were fabricated by chemical bath deposition. Parameters including precursor concentration, pH value, reaction temperature, reaction time and addition of capping agent were optimized by using statistical experimental design to improve and optimize the growth quality of ZnO rod arrays. Through several stages of optimization, the growth quality of the obtained structures was remarkably enhanced from sparse or clustered ZnO rods to upright and dense ZnO rods. The boundary conditions to achieve vertically aligned ZnO rods, such as a neutral solution and a precursor concentration over 0.02M, were determined. The changing tendency of the texture coefficient and aspect ratio with the factors was also plotted to predict the required experimental settings for specific requests. The points or regions to achieve the optimal properties were identified as well. For instance, the concentration should be as close as to 0.1 M, while the reaction temperature should be limited to 80-90 ◦C, to achieve the ideal preferential growth. With the optimized parameters, the texture coefficient reached almost the perfect value 1, and the aspect ratio was elevated to 21. Moreover, to obtain a dense ZnO thin film, tri-sodium citrate was added to the reaction system. The diameter was systematically controlled through varying the parameters. When both the diameter and the texture coefficient reached the optimal values, the rods were merged together to form a dense ZnO thin film. Furthermore, comments on the statistical experimental method are proposed, and both the advantages and disadvantages are presented according to the present thesis work. This might help the researchers to avoid the disadvantages and thus to employ this method more efficiently in the future. / <p>QC 20150903</p>

Approved for public release; distribution in unlimited. / a beam towards the UAV. A simulation model was developed and implemented in MATLAB programming language to study the effectiveness of beamforming using sensor clusters for establishing a communication link to the UAV. Results showed that the antenna main lobe remained relatively unchanged in the presence of position errors and sensor node failures or when the density of the sensor nodes changed. Additionally, the maximum average power gain of the main lobe can be increased by increasing the density of the sensor cluster, thereby increasing the transmission range between the sensor clusters and the UAV. / Civilian, Singapore Ministry of Defense

A Distributed Multi-Input Multi-Output (DMIMO) system consists of many transceivers coordinating themselves into a "virtual antenna array" in order to emulate MIMO capabilities. In recent years, the field of research investigating DMIMO Communications has grown substantially. DMIMO systems offer all of the same benefits of standard MIMO systems on a larger scale because arrays are not limited by the physical constraint of placing many antennas on a single transceiver. This additional benefit does come at a cost, however. Since nodes are distributed and run from independent clock signals and with unknown geometry, each one must its own obtain channel state information (CSI) to the target nodes. In existing DMIMO architectures, array nodes depend on feedback from target nodes to properly synchronize. This means that target nodes must be cooperative and are responsible for the overhead calculating and transmitting CSI feedback to each node in the array. Within this work, we develop a set of techniques for Retrodirective Distributed Antenna Arrays. Retrodirective arrays have traditionally been used to direct a beam towards a target node, but the work in this thesis seeks to develop a more generalized definition of retrodirectivity. By our definition, a retrodirective array is one that acquires CSI to one or more intended targets simply by listening to the incoming transmissions of those targets; the array may subsequently use this information to do any number of typical MIMO tasks (i.e., beamforming, nullforming, spatial multiplexing, etc.). We explore two primary techniques: i) distributed beamforming and ii) distributed nullforming. Beamforming involves focusing transmitted power towards a specific target node and nullforming involves directing transmissions of array nodes to cancel one another at a specific target node. We focus on these techniques because they can be thought of as basic building blocks for more sophisticated DMIMO techniques. We first develop the theory for retrodirective arrays. Then, we present an architecture for the implementation of this theory. Specifically, we focus on the pre-synchronization of the array, which involves use of a master/slave architecture and a timeslotted message exchange among the array nodes. Finally, developing algorithms to make these arrays both robust and scalable is the focus of this thesis.

This thesis considers the design of a beamformer which can enhance desired signals in an environment consisting of broadband nearfield and/or farfield sources. The thesis contains: a formulation of a set of analysis tools which can provide insight into the intrinsic structure of array processing problems; a methodology for nearfield beamforming; theory and design of a general broadband beamformer; and a consideration of a coherent nearfield broadband adaptive beamforming problem. To a lesser extent, the source localization problem and background noise modeling are also treated. ¶: A set of analysis tools called modal analysis techniques which can be used to a solve wider class of array signal processing problems, is first formulated. The solution to the classical wave equation is studied in detail and exploited in order to develop these techniques. ¶: Three novel methods of designing a beamformer having a desired nearfield broadband beampattern are presented. The first method uses the modal analysis techniques to transform the desired nearfield beampattern to an equivalent farfield beampattern. A farfield beamformer is then designed for a transformed farfield beampattern which, if achieved, gives the desired nearfield pattern exactly. The second method establishes an asymptotic equivalence, up to complex conjugation, of two problems: (i) determining the nearfield performance of a farfield beampattern specification, and (ii) determining the equivalent farfield beampattern corresponding to a nearfield beampattern specification. Using this reciprocity relationship a computationally simple nearfield beamforming procedure is developed. The third method uses the modal analysis techniques to find a linear transformation between the array weights required to have the desired beampattern for farfield and nearfield, respectively. ¶: An efficient parameterization for the general broadband beamforming problem is introduced with a single parameter to focus the beamformer to a desired operating radius and another set of parameters to control the actual broadband beampattern shape. This parameterization is derived using the modal analysis techniques and the concept of the theoretical continuous aperture. ¶: A design of an adaptive beamformer to operate in a signal environment consisting of broadband nearfield sources, where some of interfering signals may be correlated with desired signal is also considered. Application of modal analysis techniques to noise modeling and broadband coherent source localization conclude the thesis.

As integrated circuits become smaller in size, antenna design has become the size limiting factor for RF front ends. The size reduction of an antenna is limited due to tradeoffs between its size and its performance. Thus, combining antenna designs with other system components can reutilize parts of the system and significantly reduce its overall size. The biggest challenge is in minimizing the interference between the antenna and other components so that the radiation performance is not compromised. This is especially true for antenna arrays where the radiation pattern is important. Antenna size reduction is also desired for wireless sensors where the devices need to be unnoticeable to the subjects being monitored. In addition to reducing the interference between components, the environmental effect on the antenna needs to be considered based on sensors' deployment. This dissertation focuses on solving the two challenges: 1) designing compact multi-frequency arrays that maintain directive radiation across their operating bands and 2) developing integrated antennas for sensors that are protected against hazardous environmental conditions. The first part of the dissertation addresses various multi-frequency directive antennas arrays that can be used for base stations, aerospace/satellite applications. A cognitive radio base station antenna that maintains a consistent radiation pattern across the operating frequencies is introduced. This is followed by multi-frequency phased array designs that emphasize light-weight and compactness for aerospace applications. The size and weight of the antenna element is reduced by using paper-based electronics and internal cavity structures. The second part of the dissertation addresses antenna designs for sensor systems such as wireless sensor networks and RFID-based sensors. Solar cell integrated antennas for wireless sensor nodes are introduced to overcome the mechanical weakness posed by conventional monopole designs. This can significantly improve the sturdiness of the sensor from environmental hazards. The dissertation also introduces RFID-based strain sensors as a low-cost solution to massive sensor deployments. With an antenna acting as both the sensing device as well as the communication medium, the cost of an RFID sensor is dramatically reduced. Sensors' strain sensitivities are measured and theoretically derived. Their environmental sensitivities are also investigated to calibrate them for real world applications.

Catalyzed by protein kinases, phosphorylation is the most important post-translational modification in eukaryotes and is involved in the regulation of almost all cellular processes. Investigating phosphorylation events and how they change in response to different biological conditions is integral to understanding cellular signaling processes in general, as well as to defining the role of phosphorylation in health and disease. A recently-developed technology for studying phosphorylation events is the kinome microarray, which consists of several hundred "spots" arranged in a grid-like pattern on a glass slide. Each spot contains many peptides of a particular amino acid sequence chemically fixed to the slide, with different spots containing peptides with different sequences. Each peptide is a subsequence of a full protein, containing an amino acid residue that is known or suspected to undergo phosphorylation in vivo, as well as several surrounding residues. When a kinome microarray is exposed to cell lysate, the protein kinases in the lysate catalyze the phosphorylation of the peptides on the array. By measuring the degree to which the peptides comprising each spot are phosphorylated, insight can be gained into the upregulation or downregulation of signaling pathways in response to different biological treatments or conditions. There are two main computational challenges associated with kinome microarrays. The first is array design, which involves selecting the peptides to be included on a given array. The level of difficulty of this task depends largely on the number of phosphorylation sites that have been experimentally identified in the proteome of the organism being studied. For instance, thousands of phosphorylation sites are known for human and mouse, allowing considerable freedom to select peptides that are relevant to the problem being examined. In contrast, few sites are known for, say, honeybee and soybean. For such organisms, it is useful to expand the set of possible peptides by using computational techniques to predict probable phosphorylation sites. In this thesis, existing techniques for the computational prediction of phosphorylation sites are reviewed. In addition, two novel methods are described for predicting phosphorylation events in organisms with few known sites, with each method using a fundamentally different approach. The first technique, called PHOSFER, uses a random forest-based machine-learning strategy, while the second, called DAPPLE, takes advantage of sequence homology between known sites and the proteome of interest. Both methods are shown to allow quicker or more accurate predictions in organisms with few known sites than comparable previous techniques. Therefore, the use of kinome microarrays is no longer limited to the study of organisms having many known phosphorylation sites; rather, this technology can potentially be applied to any organism having a sequenced genome. It is shown that PHOSFER and DAPPLE are suitable for identifying phosphorylation sites in a wide variety of organisms, including cow, honeybee, and soybean. The second computational challenge is data analysis, which involves the normalization, clustering, statistical analysis, and visualization of data resulting from the arrays. While software designed for the analysis of DNA microarrays has also been used for kinome arrays, differences between the two technologies prompted the development of PIIKA, a software package specifically designed for the analysis of kinome microarray data. By comparing with methods used for DNA microarrays, it is shown that PIIKA improves the ability to identify biological pathways that are differentially regulated in a treatment condition compared to a control condition. Also described is an updated version, PIIKA 2, which contains improvements and new features in the areas of clustering, statistical analysis, and data visualization. Given the previous absence of dedicated tools for analyzing kinome microarray data, as well as their wealth of features, PIIKA and PIIKA 2 represent an important step in maximizing the scientific value of this technology. In addition to the above techniques, this thesis presents three studies involving biological applications of kinome microarray analysis. The first study demonstrates the existence of "kinotypes" - species- or individual-specific kinome profiles - which has implications for personalized medicine and for the use of model organisms in the study of human disease. The second study uses kinome analysis to characterize how the calf immune system responds to infection by the bacterium Mycobacterium avium subsp. paratuberculosis. Finally, the third study uses kinome arrays to study parasitism of honeybees by the mite Varroa destructor, which is thought to be a major cause of colony collapse disorder. In order to make the methods described above readily available, a website called the SAskatchewan PHosphorylation Internet REsource (SAPHIRE) has been developed. Located at the URL http://saphire.usask.ca, SAPHIRE allows researchers to easily make use of PHOSFER, DAPPLE, and PIIKA 2. These resources facilitate both the design and data analysis of kinome microarrays, making them an even more effective technique for studying cellular signaling.

Reduced-control antenna arrays reduce the number of controls required for beamforming while maintaining a given array aperture. A reduced-control array for direction finding (DF), inspired by the concept of compressive sensing (CS), was recently proposed which uses random compression weights for combining antenna-element signals into fewer measurements. However, this compressive array had not been studied in terms of traditional characteristics such as directivity, sidelobe level (SLL) or beamwidth. In this work, random compression weights are shown to be suboptimal and a need for the optimisation of compressive arrays is expressed. Existing codebook optimisation algorithms prove to be the best starting point for the optimisation of compressive arrays, but are computationally complex. A computationally efficient codebook optimisation algorithm is proposed to address this problem, which inspires the compressive-array optimisation algorithm to follow. Compressive antenna arrays are formulated as a generalisation of reduced-control arrays and a framework is presented for their optimisation in terms of SLL. By allowing arbitrary compression weights, compressive arrays are shown to improve on existing reduced-control techniques. A feed network consisting of interconnected couplers and fixed phase shifters is proposed, enabling the implementation of compressive arrays in microwave hardware. The practical feasibility of compressive arrays is illustrated by successfully manufacturing a 3-GHz prototype compressive array with integrated antenna elements. / Thesis (PhD)--University of Pretoria, 2020. / Electrical, Electronic and Computer Engineering / PhD / Unrestricted