Mak Sui Tung Terrence. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 132-142). / Abstracts in English and Chinese. / Abstract --- p.i / List of Tables --- p.iv / List of Figures --- p.v / Acknowledgements --- p.ix / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Bioinformatics --- p.1 / Chapter 1.2 --- Neural Prosthetics --- p.4 / Chapter 1.3 --- Learning in Uncertainty --- p.5 / Chapter 1.4 --- The Field Programmable Gate Array (FPGAs) --- p.7 / Chapter 1.5 --- Scope of the Thesis --- p.10 / Chapter 2. --- A Hybrid GA-DP Approach for Searching Equivalence Sets --- p.14 / Chapter 2.1 --- Introduction --- p.16 / Chapter 2.2 --- Equivalence Set Criterion --- p.18 / Chapter 2.3 --- Genetic Algorithm and Dynamic Programming --- p.19 / Chapter 2.3.1 --- Genetic Algorithm Formulation --- p.20 / Chapter 2.3.2 --- Bounded Mutation --- p.21 / Chapter 2.3.3 --- Conditioned Crossover --- p.22 / Chapter 2.3.4 --- Implementation --- p.22 / Chapter 2.4 --- FPGAs Implementation of GA-DP --- p.24 / Chapter 2.4.1 --- System Overview --- p.25 / Chapter 2.4.2 --- Parallel Computation for Transitive Closure --- p.26 / Chapter 2.4.3 --- Genetic Operation Realization --- p.28 / Chapter 2.5 --- Discussion --- p.30 / Chapter 2.6 --- Limitation and Future Work --- p.33 / Chapter 2.7 --- Conclusion --- p.34 / Chapter 3. --- An FPGA-based Architecture for Maximum-Likelihood Phylogeny Evaluation --- p.35 / Chapter 3.1 --- Introduction --- p.36 / Chapter 3.2 --- Maximum-Likelihood Model --- p.39 / Chapter 3.3 --- Hardware Mapping for Pruning Algorithm --- p.41 / Chapter 3.3.1 --- Related Works --- p.41 / Chapter 3.3.2 --- Number Representation --- p.42 / Chapter 3.3.3 --- Binary Tree Representation --- p.43 / Chapter 3.3.4 --- Binary Tree Traversal --- p.45 / Chapter 3.3.5 --- Maximum-Likelihood Evaluation Algorithm --- p.46 / Chapter 3.4 --- System Architecture --- p.49 / Chapter 3.4.1 --- Transition Probability Unit --- p.50 / Chapter 3.4.2 --- State-Parallel Computation Unit --- p.51 / Chapter 3.4.3 --- Error Computation --- p.54 / Chapter 3.5 --- Discussion --- p.56 / Chapter 3.5.1 --- Hardware Resource Consumption --- p.56 / Chapter 3.5.2 --- Delay Evaluation --- p.57 / Chapter 3.6 --- Conclusion --- p.59 / Chapter 4. --- Field Programmable Gate Array Implementation of Neuronal Ion Channel Dynamics --- p.61 / Chapter 4.1 --- Introduction --- p.62 / Chapter 4.2 --- Background --- p.63 / Chapter 4.2.1 --- Analog VLSI Model for Hebbian Synapse --- p.63 / Chapter 4.2.2 --- A Unifying Model of Bi-directional Synaptic Plasticity --- p.64 / Chapter 4.2.3 --- Non-NMDA Receptor Channel Regulation --- p.65 / Chapter 4.3 --- FPGAs Implementation --- p.65 / Chapter 4.3.1 --- FPGA Design Flow --- p.65 / Chapter 4.3.2 --- Digital Model of NMD A and AMPA receptors --- p.65 / Chapter 4.3.3 --- Synapse Modification --- p.67 / Chapter 4.4 --- Results --- p.68 / Chapter 4.4.1 --- Simulation Results --- p.68 / Chapter 4.5 --- Discussion --- p.70 / Chapter 4.6 --- Conclusion --- p.71 / Chapter 5. --- Continuous-Time and Discrete-Time Inference Networks for Distributed Dynamic Programming --- p.72 / Chapter 5.1 --- Introduction --- p.74 / Chapter 5.2 --- Background --- p.77 / Chapter 5.2.1 --- Markov decision process (MDPs) --- p.78 / Chapter 5.2.2 --- Learning in the MDPs --- p.80 / Chapter 5.2.3 --- Bellman Optimal Criterion --- p.80 / Chapter 5.2.4 --- Value Iteration --- p.81 / Chapter 5.3 --- A Computational Framework for Continuous-Time Inference Network --- p.82 / Chapter 5.3.1 --- Binary Relation Inference Network --- p.83 / Chapter 5.3.2 --- Binary Relation Inference Network for MDPs --- p.85 / Chapter 5.3.3 --- Continuous-Time Inference Network for MDPs --- p.87 / Chapter 5.4 --- Convergence Consideration --- p.88 / Chapter 5.5 --- Numerical Simulation --- p.90 / Chapter 5.5.1 --- Example 1: Random Walk --- p.90 / Chapter 5.5.2 --- Example 2: Random Walk on a Grid --- p.94 / Chapter 5.5.3 --- Example 3: Stochastic Shortest Path Problem --- p.97 / Chapter 5.5.4 --- Relationships Between λ and γ --- p.99 / Chapter 5.6 --- Discrete-Time Inference Network --- p.100 / Chapter 5.6.1 --- Results --- p.101 / Chapter 5.7 --- Conclusion --- p.102 / Chapter 6. --- On Distributed g-Learning Network --- p.104 / Chapter 6.1 --- Introduction --- p.105 / Chapter 6.2 --- Distributed Q-Learniing Network --- p.108 / Chapter 6.2.1 --- Distributed Q-Learning Network --- p.109 / Chapter 6.2.2 --- Q-Learning Network Architecture --- p.111 / Chapter 6.3 --- Experimental Results --- p.114 / Chapter 6.3.1 --- Random Walk --- p.114 / Chapter 6.3.2 --- The Shortest Path Problem --- p.116 / Chapter 6.4 --- Discussion --- p.120 / Chapter 6.4.1 --- Related Work --- p.121 / Chapter 6.5 --- FPGAs Implementation --- p.122 / Chapter 6.5.1 --- Distributed Registering Approach --- p.123 / Chapter 6.5.2 --- Serial BRAM Storing Approach --- p.124 / Chapter 6.5.3 --- Comparison --- p.125 / Chapter 6.5.4 --- Discussion --- p.127 / Chapter 6.6 --- Conclusion --- p.128 / Chapter 7. --- Summary --- p.129 / Bibliography --- p.132 / Appendix / Chapter A. --- Simplified Floating-Point Arithmetic --- p.143 / Chapter B. --- "Logarithm, Exponential and Division Implementation" --- p.144 / Chapter B.1 --- Introduction --- p.144 / Chapter B.2 --- Approximation Scheme --- p.145 / Chapter B.2.1 --- Logarithm --- p.145 / Chapter B.2.2 --- Exponentiation --- p.147 / Chapter B.2.3 --- Division --- p.148 / Chapter C. --- Analog VLSI Implementation --- p.150 / Chapter C.1 --- Site Function --- p.150 / Chapter C.1.1 --- Multiplication Cell --- p.150 / Chapter C.2 --- The Unit Function --- p.153 / Chapter C.3 --- The Inference Network Computation --- p.154 / Chapter C.4 --- Layout --- p.157 / Chapter C.5 --- Fabrication --- p.159 / Chapter C.5.1 --- Testing and Characterization --- p.161

(I) Architectural revisions: Probably due to historical reasons, programmable switches on conventional FPGA architectures are divided into two kinds of substructures: Connection boxes (C-boxes) and Switch boxes (S-boxes), where C-boxes are used to connect logic/pad pins with their crossing wire segments, and S-boxes are used to connect wire segments of surrounding routing channels. In this work, we will challenge if this divided C- and S-boxes structure is really necessary and will explore a new experimental architecture which adopts only one kind of switching components - Connection-Switch boxes (CS-boxes). Extensive experiments are conducted on MCNC benchmark circuits to justify its architectural performance impacts. The results show that this CS-box based FPGA outperforms the conventional FPGA in terms of channel width, circuit delay, and segment usage. Besides an over 20% drastic dropping in the total number of manufactured switches needed, circuit delay performance is improved by 10% under the usage of the same pin assignments and router. / (II) New EDA technique/flow: By applying circuit rewirings, logic perturbations can be carried out by shifting logic resources from perhaps costly Look-Up-Table (LUT) external to cost-free LUT internal areas, or from critical to non-critical paths. This work presents a simple, while effective and low-overhead postlayout logic perturbation scheme for improving LUT-based FPGA routings without altering placements. A rewiring-based logic perturbation technique is used to improve upon a timing-driven FPGA P&R tool - TVPR. Compared with the already high-quality pure TVPR results, our approach reduces critical path delay by up to 31.74% (avg. 11%) without disturbing the placement or sacrificing chip areas, where only 4% of the nets are perturbed in our scheme. The complexity of our algorithm is linear in the total number of nets of the circuit. The experimental results show that the CPU time used by the rewiring engine is only 5% of the total time consumed by the placement and routing of TVPR. / Based on these studies, we believe the prospect for FPGA performance improvement is still quite profound in both architectural and EDA aspects. On the EDA technique, we have also performed logic perturbations to improve both the technology mapping and routing to investigate the effectiveness of the logic perturbation if applied in a larger context. The results show that a best technology mapping is not always leading to a best final routing, which seems to suggest that an ideal FPGA EDA flow should consider more on trade-offs between different stages. To the best of our knowledge, this is the first work exploring the power of logic perturbations applied for multiple physical stages for LUT-based FPGAs. The encouraging hardware improvement shown in our proposed CS-box based FPGAs seems to suggest a new design direction for FPGA routing architectures. / With the advent of deep submicron technologies, the extreme high design and mask costs incurred for ASICs have made FPGAs an increasingly popular hardware implementation option. However, it has been shown that the programmable routing structure underlined contributes over 60% of the signal delay and as high as 90% of the total chip area. As a result, current FPGAs still cannot meet performance requirements of many high-end applications. To attack this issue, we propose new solutions along the two major tracks: (I) architectural revisions (hardware) and (II) new EDA technique/flow (software). / Zhou Lin. / "October 2007." / Adviser: Yu-Liang Wu. / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4953. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 101-108). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Leung Ka Ho. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves [85]-90). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgments --- p.iii / List of Figures --- p.ix / List of Tables --- p.xi / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Aims --- p.3 / Chapter 1.3 --- Contributions --- p.3 / Chapter 1.4 --- Thesis Outline --- p.4 / Chapter 2 --- Cryptography --- p.6 / Chapter 2.1 --- Introduction --- p.6 / Chapter 2.2 --- Foundations --- p.6 / Chapter 2.3 --- Secret Key Cryptosystems --- p.8 / Chapter 2.4 --- Public Key Cryptosystems --- p.9 / Chapter 2.4.1 --- One-way Function --- p.10 / Chapter 2.4.2 --- Certification Authority --- p.10 / Chapter 2.4.3 --- Discrete Logarithm Problem --- p.11 / Chapter 2.4.4 --- RSA vs. ECC --- p.12 / Chapter 2.4.5 --- Key Exchange Protocol --- p.13 / Chapter 2.4.6 --- Digital Signature --- p.14 / Chapter 2.5 --- Secret Key vs. Public Key Cryptography --- p.16 / Chapter 2.6 --- Summary --- p.18 / Chapter 3 --- Mathematical Background --- p.19 / Chapter 3.1 --- Introduction --- p.19 / Chapter 3.2 --- Groups and Fields --- p.19 / Chapter 3.3 --- Finite Fields --- p.21 / Chapter 3.4 --- Modular Arithmetic --- p.21 / Chapter 3.5 --- Polynomial Basis --- p.21 / Chapter 3.6 --- Optimal Normal Basis --- p.22 / Chapter 3.6.1 --- Addition --- p.23 / Chapter 3.6.2 --- Squaring --- p.24 / Chapter 3.6.3 --- Multiplication --- p.24 / Chapter 3.6.4 --- Inversion --- p.30 / Chapter 3.7 --- Summary --- p.33 / Chapter 4 --- Literature Review --- p.34 / Chapter 4.1 --- Introduction --- p.34 / Chapter 4.2 --- Hardware Elliptic Curve Implementation --- p.34 / Chapter 4.2.1 --- Field Processors --- p.34 / Chapter 4.2.2 --- Curve Processors --- p.36 / Chapter 4.3 --- Software Elliptic Curve Implementation --- p.36 / Chapter 4.4 --- Summary --- p.38 / Chapter 5 --- Introduction to Elliptic Curves --- p.39 / Chapter 5.1 --- Introduction --- p.39 / Chapter 5.2 --- Historical Background --- p.39 / Chapter 5.3 --- Elliptic Curves over R2 --- p.40 / Chapter 5.3.1 --- Curve Addition and Doubling --- p.41 / Chapter 5.4 --- Elliptic Curves over Finite Fields --- p.44 / Chapter 5.4.1 --- Elliptic Curves over Fp with p>〉3 --- p.44 / Chapter 5.4.2 --- Elliptic Curves over F2n --- p.45 / Chapter 5.4.3 --- Operations of Elliptic Curves over F2n --- p.46 / Chapter 5.4.4 --- Curve Multiplication --- p.49 / Chapter 5.5 --- Elliptic Curve Discrete Logarithm Problem --- p.51 / Chapter 5.6 --- Public Key Cryptography --- p.52 / Chapter 5.7 --- Elliptic Curve Diffie-Hellman Key Exchange --- p.54 / Chapter 5.8 --- Summary --- p.55 / Chapter 6 --- Design Methodology --- p.56 / Chapter 6.1 --- Introduction --- p.56 / Chapter 6.2 --- CAD Tools --- p.56 / Chapter 6.3 --- Hardware Platform --- p.59 / Chapter 6.3.1 --- FPGA --- p.59 / Chapter 6.3.2 --- Reconfigurable Hardware Computing --- p.62 / Chapter 6.4 --- Elliptic Curve Processor Architecture --- p.63 / Chapter 6.4.1 --- Arithmetic Logic Unit (ALU) --- p.64 / Chapter 6.4.2 --- Register File --- p.68 / Chapter 6.4.3 --- Microcode --- p.69 / Chapter 6.5 --- Parameterized Module Generator --- p.72 / Chapter 6.6 --- Microcode Toolkit --- p.73 / Chapter 6.7 --- Initialization by Bitstream Reconfiguration --- p.74 / Chapter 6.8 --- Summary --- p.75 / Chapter 7 --- Results --- p.76 / Chapter 7.1 --- Introduction --- p.76 / Chapter 7.2 --- Elliptic Curve Processor with Serial Multiplier (p = 1) --- p.76 / Chapter 7.3 --- Projective verses Affine Coordinates --- p.78 / Chapter 7.4 --- Elliptic Curve Processor with Parallel Multiplier (p > 1) --- p.79 / Chapter 7.5 --- Summary --- p.80 / Chapter 8 --- Conclusion --- p.82 / Chapter 8.1 --- Recommendations for Future Research --- p.83 / Bibliography --- p.85 / Chapter A --- Elliptic Curves in Characteristics 2 and3 --- p.91 / Chapter A.1 --- Introduction --- p.91 / Chapter A.2 --- Derivations --- p.91 / Chapter A.3 --- "Elliptic Curves over Finite Fields of Characteristic ≠ 2,3" --- p.92 / Chapter A.4 --- Elliptic Curves over Finite Fields of Characteristic = 2 --- p.94 / Chapter B --- Examples of Curve Multiplication --- p.95 / Chapter B.1 --- Introduction --- p.95 / Chapter B.2 --- Numerical Results --- p.96

The increasing commoditization of computers in modern society has exceeded the pace of associated developments in reliability. Although theoretical computer science has advanced greatly in the last thirty years, many of the best techniques have yet to find their way into embedded computers, and their failure can have a great potential for disrupting society. This dissertation presents some approaches to improve computer reliability using software and hardware techniques, and makes the following claims for novelty: innovative development of a toolchain and libraries to support extraction from dependent type checking in a theorem prover; conceptual design and deployment in reconfigurable hardware; an extension of static type-safety to hardware description language and FPGA level; elimination of legacy C code from the target and toolchain; a novel hardware error detection scheme is described and compared with conventional triple modular redundancy. The elimination of any user control of memory management promotes robustness against buffer overruns, and consequently prevents vulnerability to common Trojan techniques. The methodology identifies type punning as a key weakness of commonly encountered embedded languages such as C, in particular the extreme difficulty of determining if an array access is in bounds, or if dynamic memory has been properly allocated and released. A method of eliminating dependence on type-unsafe libraries is presented, in conjunction with code that has optionally been proved correct according to user-defined criteria. An appropriately defined subset of OCaml is chosen with support for the Coq theorem prover in mind, and then evaluated with a custom backend that supports behavioural Verilog, as well as a fixed execution unit and associated control store. Results are presented for this alternative platform for reliable embedded systems development that may be used in future industrial flows. To provide assurance of correct operation, the proven software needs to be executed in an environment where errors are checked and corrected in conjunction with appropriate exception processing in the event of an uncorrectable error. Therefore, the present author’s previously published error detection scheme based on dual-rail logic and self-checking checkers is further developed and compared with traditional N-modular redundancy.

Field-Programmable Gate Arrays (FPGAs) são largamente utilizadas em sistemas digitais por características como flexibilidade, baixo custo e alta densidade. Estas características advém do uso de células de SRAM na memória de configuração, o que torna estes dispositivos suscetíveis a erros induzidos por radiação, tais como SEUs. TMR é o método de mitigação mais utilizado, no entanto, possui um elevado custo tanto em área como em energia, restringindo seu uso em aplicações de baixo custo e/ou baixo consumo. Como alternativa a TMR, propõe-se utilizar DMR associado a um mecanismo de reparo da memória de configuração da FPGA chamado scrubbing. O reparo de FPGAs em sistemas em tempo real apresenta desafios específicos. Além da garantia da computação correta dos dados, esta computação deve se dar completamente dentro do tempo disponível (time-slot), devendo ser finalizada antes do tempo limite (deadline). A diferença entre o tempo de computação dos dados e a deadline é chamado de slack e é o tempo disponível para reparo do sistema. Este trabalho faz uso de scrubbing deslocado dinâmico, que busca maximizar a probabilidade de reparo da memória de configuração de FPGAs dentro do slack disponível, baseado em um diagnóstico do erro. O scrubbing deslocado já foi utilizado com técnicas de diagnóstico de grão fino (NAZAR, 2015). Este trabalho propõe o uso de técnicas de diagnóstico de grão grosso para o scrubbing deslocado, evitando as penalidades de desempenho e custos em área associados a técnicas de grão fino. Circuitos do conjunto MCNC foram protegidos com as técnicas propostas e submetidos a seções de injeção de erros (NAZAR; CARRO, 2012a). Os dados obtidos foram analisados e foram calculadas as melhores posição iniciais do scrubbing para cada um dos circuitos. Calculou-se a taxa de Failure-in-Time (FIT) para comparação entre as diferentes técnicas de diagnóstico propostas. Os resultados obtidos confirmaram a hipótese inicial deste trabalho que a redução do número de bits sensíveis e uma baixa degradação do período do ciclo de relógio permitiram reduzir a taxa de FIT quando comparadas com técnicas de grão fino. Por fim, uma comparação entre as três técnicas propostas é feita, analisando o desempenho e custos em área associados a cada uma. / Field-Programmable Gate Arrays (FPGAs) are widely used in digital systems due to characteristics such as flexibility, low cost and high density. These characteristics are due to the use of SRAM memory cells in the configuration memory, which make these devices susceptible to radiation-induced errors, such as SEUs. TMR is the most used mitigation technique, but it has an elevated cost both in area as well as in energy, restricting its use in low cost/low energy applications. As an alternative to TMR, we propose the use of DMR associated with a repair mechanism of the FPGA configuration memory called scrubbing. The repair of FPGA in real-time systems present a specific set of challenges. Besides guaranteeing the correct computation of data, this computation must be completely carried out within the available time (time-slot), being finalized before a time limit (deadline). The difference between the computation time and the deadline is called the slack and is the time available to repair the system. This work uses a dynamic shifted scrubbing that aims to maximize the repair probability of the configuration memory of the FPGA within the available slack based on error diagnostic. The shifted scrubbing was already proposed with fine-grained diagnostic techniques (NAZAR, 2015). This work proposes the use of coarse-grained diagnostic technique as a way to avoid the performance penalties and area costs associated to fine-grained techniques. Circuits of the MCNC suite were protected by the proposed techniques and subject to error-injection campaigns (NAZAR; CARRO, 2012a). The obtained data was analyzed and the best scrubbing starting positions for each circuit were calculated. The Failure-in-Time (FIT) rates were calculated to compare the different proposed diagnostic techniques. The obtained results validated the initial hypothesis of this work that the reduction of the number of sensitive bits and a low degradation of the clock cycle allowed a reduced FIT rate when compared with fine-grained diagnostic techniques. Finally, a comparison is made between the proposed techniques, considering performance and area costs associated to each one.

The FFT is an efficient algorithm for computing the DFT. It drastically reduces the cost of implementing the DFT on digital computing systems. Nevertheless, the FFT is still computationally intensive, and continued technological advances of computers demand larger and faster implementations of this algorithm. Past attempts at producing high-performance, and small FFT implementations, have focused on custom hardware (ASICs and FPGAs). Ultimately, the most efficient have been single-chipped, streaming I/O, pipelined FFT architectures. These architectures increase computational concurrency through the use of hardware pipelining. Streaming I/O, pipelined FFT architectures are capable of accepting a single data sample every clock cycle. In principle, the maximum clock frequency of such a circuit is limited only by its critical delay path. The delay of the critical path may be decreased by the addition of pipeline registers. Nevertheless this solution gives diminishing returns. Thus, the streaming I/O, pipelined FFT is ultimately limited in the maximum performance it can provide. Attempts have been made to map the Parallel FFT algorithm to custom hardware. Yet, the Parallel FFT was formulated and optimized to execute on a machine with multiple, identical, processing elements. When executed on such a machine, the FFT requires a large expense on communications. Therefore, a direct mapping of the Parallel FFT to custom hardware results in a circuit with complex control and global data movement. This thesis proposes the Hybrid Architecture Parallel FFT (HAPFFT) as an alternative. The HAPFFT is an improved formulation for building Parallel FFT custom hardware modules. It provides improved performance, efficient resource utilization, and reduced design time. The HAPFFT is modular in nature. It includes a custom front-end parallel processing unit which produces intermediate results. The intermediate results are sent to multiple, independent FFT modules. These independent modules form the back-end of the HAPFFT, and are generic, meaning that any prexisting FFT architecture may be used. With P back-end modules a speedup of P will be achieved, in comparison to an FFT module composed solely of a single module. Furthermore, the HAPFFT defines the front-end processing unit as a function of P. It hides the high communication costs typically seen in Parallel FFTs. Reductions in control complexity, memory demands, and logical resources, are achieved. An extraordinary result of the HAPFFT formulation is a sublinear area-time growth. This phenomenon is often also called superlinear speedup. Sublinear area-time growth and superlinear speedup are equivalent terms. This thesis will subsequently use the term superlinear speedup to refer to the HAPFFT's outstanding speedup behavior. A further benefit resulting from the HAPFFT formulation is reduced design time. Because the HAPFFT defines only the front-end module, and because the back-end parallel modules may be composed of any preexisting FFT modules, total design time for a HAPFFT is greatly reduced

Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores - Major Telecomunicações. Faculdade de Engenharia. Universidade do Porto. 2013

Cavity ringdown spectroscopy (CRDS) makes use of light retention in an optical cavity to enhance the sensitivity to absorption or extinction of light from a sample inside the cavity. When light entering the cavity is stopped, the output is an exponential decay with a decay constant that can be used to determine the quantity of the analyte if the extinction or absorption coefficient is known. The precision of the CRDS is dependent on the rate at which the system it acquires and processes ringdowns, assuming randomly distributed errors. We have demonstrated a CRDS system with a ringdown acquisition rate of 1.5 kHz, extendable to a maximum of 3.5 kHz, using new techniques that significantly changed the way in which the ringdowns are both initiated and processed. On the initiation side, we combined a custom high-resolution laser controller with a linear optical feedback configuration and a novel optical technique for initiating a ringdown. Our optical injection "unlock" method switches the laser off-resonance, while allowing the laser to immediately return to resonance, after terminating the unlock, to allow for another ringdown (on the same cavity resonance mode). This part of the system had a demonstrated ringdown initiation rate of 3.5 kHz. To take advantage of this rate, we developed an optimized cost-effective FGPA-based data acquisition and processing system for CRDS, capable of determining decay constants at a maximum rate of 4.4 kHz, by modifying a commercial ADC-FPGA evaluation board and programming it to apply a discrete Fourier transform-based algorithm for determining decay constants. The entire system shows promise with a demonstrated ability to determine gas concentrations for H2O with a measured concentration accuracy of ±3.3%. The system achieved an absorption coefficient precision of 0.1% (95% confidence interval). It also exhibited a linear response for varying H2O concentrations, a 2.2% variation (1σ) for repeated measurements at the same H2O concentration, and a corresponding precision of 0.6% (standard error of the mean). The absorption coefficient limit of detection was determined to be 1.6 x 10-8 cm-1 (root mean square of the baseline residual). Proposed modifications to our prototype system offer the promise of more substantial gains in both precision and limit of detection. The system components developed here for faster ringdown acquisition and processing have broader applications for CRDS in atmospheric science and other fields that need fast response systems operating at high-precision.

This thesis presents a new technique for mapping combinational circuits to Fine-Grain Cellular-Architecture FPGAs. We represent the netlist as the binary tree with decision variables associated with each node of the tree. The functionality of the tree nodes is chosen based on the target FPGA architecture. The proposed tree restructuring algorithms preserve local connectivity and allow direct mapping of the trees to the cellular array, thus eliminating the traditional routing phase. Also, predictability of the signal delays is a very important advantage of the developed approach. The developed bus-assignment algorithm efficiently utilizes the medium distance routing resources (buses). The method is general and can be used for any Fine Grain CA-type FPGA. To demonstrate our techniques, ATMEL 6000 series FPGA was used as a target architecture. The area and delay comparison between our methods and commercial tools is presented using a set of MCNC benchmarks. Final layouts of the implemented designs are included. Results show that the proposed techniques outperform the available commercial tools for ATMEL 6000 FPGAs, both in area and delay optimization.

Unmanned vehicles, both ground and aerial, have become prevalent in recent years. The research community has different needs than the industrial community when designing a finalized unmanned system since the vehicle, the sensors and the control design are dynamic and change frequently as new ideas are developed and implemented. Current autopilot hardware, which is available as on-the-market products and proposed in research, is sufficient for unmanned systems design. However, this equipment falls short of being able to accommodate the needs of those in the research community who must be able to quickly implement new ideas on a flexible platform. The contribution of this research is the realization of a hardware platform, which provides for rapid implementation of newly developed theory. Rapid implementation is gained by providing for software development from within the Simulink environment and utilizing previously unrealized flexibility in sensor selection. In addition to the development of the hardware platform, research was performed within Simulink's System Generator environment in order to complement the hardware. The software produced consists of a user template that integrates to the selected hardware. The template creates a user friendly environment, which provides the end user the capability to develop software algorithms from within the Simulink environment. This capability facilitates the final step of full hardware implementation. The major novelty of the research was the overall FPGA based autopilot design. The approach provided flexibility, functionality and generality. The approach is also suitable for and applicable to the design of multiple platforms. This research yielded a first time approach to the development of an unmanned systems autopilot platform by utilizing: -Development of programmable voltage level digital Input/Output (I/O), ports, -Utilization of Field Programmable Analog Arrays (FPAA), -Hardware capabilities to allow for integration with full computer systems, -A full Field Programmable Gate Array (FPGA), implementation, -Full integration of the hardware within Simulink's System Generator Toolbox