<p>In this thesis, we investigate the problem of Unmanned Aerial Vehicle (UAV) path planning in search or surveillance mission, when some a priori information about the targets and the environment is available. A search operation that utilizes the available a priori information about the initial location of the targets, terrain data, and information from reasonable assumptions about the targets movement can in average perform better than a uniform search that does not incorporate this information. This thesis provides a simulation-based framework to address this type of problem. Search operations are generally dynamic and should be modified during the mission due to new reports from other sources, new sensor observations, and/or changes in the environment, therefore a Symbiotic Simulation method that employs the latest data is suggested. All available information is continuously fused using Particle Filtering to yield an updated picture of the probability density of the target. This estimation is used periodically to run a set of <i>what-if </i>simulations to determine which UAV path is most promising. From a set of different UAV paths the one that decreases the uncertainty about the location of the target is preferable. Hence, the expectation of information entropy is used as a measure for comparing different courses of action of the UAV. The suggested framework is applied to a test case scenario involving a single UAV searching for a single target moving on a road network. The performance of the Symbiotic Simulation search method is compared with an off-line simulation and an exhaustive search method using a simulation tool developed for this purpose. The off-line simulation differs from the Symbiotic Simulation search method in that in the former case the <i>what-if</i> simulations are conducted before the start of the mission. In the exhaustive search method the UAV searches the entire road network. The Symbiotic Simulation shows a higher performance and detects the target in the considerably shorter time than the other two methods. Furthermore, the detection time of the Symbiotic Simulation is compared with the detection time when the UAV has the exact information about the initial location of the target, its velocity and its path. This value provides a lower bound for the optimal solution and gives another indication about the performance of the Symbiotic Simulation. This comparison also suggests that the Symbiotic Simulation in many cases achieves a “near” optimal performance.</p>

<p>The advances in VLSI and packaging technologies enable us to integrate a whole system on a single chip (SoC) or on a package module. In these systems, analog/RF electronics, digital circuitries, and memories coexist. This new technology brings us new freedom for system integration as well as new challenges in system design and implementation. To fully utilize the benefits of these new hardware technologies, concurrent design of system, chip, and package is necessary. This research aims to explore the new design space and opportunities for System-on-Package (SoP), with special attention on radio and mixed-signal system applications. Global level system partitioning for SoC and SoP with cost-performance trade-off, concurrent chip and design for high-speed off-chip signaling, global clock distribution, and ultra wideband (UWB) radio module are two fields in this research.</p><p>Cost-performance driven for mixed-signal system partitioning in early conceptual level design is first addressed in this thesis. We develop a modeling technique to pre-estimate the cost and performance. The performance model evaluates various noise isolation technologies, such as using guard rings, and partitioning the system into several chips. In cost analysis, new factors such as extra chip area and additional process steps due to mixed signal isolation, integration of intellectual property (IP) right module or “virtual components”, yield and technology compatibility for merging logic, memory and analog/RF circuits on a single chip are considered. An efficient computation algorithm, namely COMSI, is developed for cost estimation under various mixed-signal performance constraints.</p><p>System interconnect topologies have been moving away from multi-point bus architecture and towards high-speed serial links. But low interaction between chip and package design has more and more limited system performance. We address concurrent chip and package design and co-optimization for high-speed off-chip signaling in this part. First we explore the interconnect and package constraints to the circuit and system architecture. Proper equivalent circuit models for package parasitics are set up and then a 3-dimension electromagnetic (EM) solver is used to extract the parasitic parameters of package. After that, bandwidth and noise of the signal channel are estimated. The optimal off-chip singling is designed according to these packages and interconnection constraints. We also analyzed the global clock distribution using co-design method.</p><p>We developed a low cost, low power consumption, and low complexity UWB radio module using co-design method and SoP technologies. The module will be used in low data rate and long-range wireless intelligent systems such as radio frequency identification (RFID) or wireless sensors networks (WSN). Liquid-crystal-polymer (LCP) based SoP technologies were used to implement the module. </p>

Positron Emission Tomography (PET) has been a very useful laboratory tool for the noninvasive study of dynamic physiological processes within the human body. Its clinical worth in cardiology, neurology, and oncology has been verified for well over a decade. Only with the most recent introduction of high performance analog and VLSI digital components yielding higher scanner resolutions at reduced costs, has clinical PET truly become a reality. The High Performance Detector Electronics System presented here represents indubitably the most advanced processing system available in the clinical PET market.

In this work the design of a constant-fraction discriminator (CFD) fabricated in the Orbit Semiconductor l.2-Jl n-well CMOS process is presented. This timing pick-off circuit is designed for use in the readout electronics of the Lead-Scintillator subsystem of the Pioneering High Eenergy Nuclear Ion eXperiment (PHENIX) Electromagnetic Calorimeter at the Relativistic Heavy Ion Collider (RHIC). The design was driven by stringent requirements including low power consumption, small area, arrayable, low cost and a fully integratable shaping network. Various integratable CFD shaping methods are investigated, and the candidate methods chosen for fabrication were the distributed R-C delay-line shaping, lumped-element R-C shaping and Nowlin method shaping. An additional channel of ideal delay-line shaping, utilizing coaxial cable to generate delay, was fabricated and used for a reference in comparing methods. These shaping methods are compared on the basis of die area, time walk performance and timing jitter performance as implemented using the CMOS CFD presented. Each shaping method investigated required no power from the dc supply. Die area for the distributed R-C delay-line, lumped-element R-C, Nowlin method and ideal delay-line (fraction circuit only) were 172 Jl X 70 Jl, 160 Jl X 65 Jl, 179 Jl X 53 Jl and 67 Jl X65Jl,respectively. Timewalkovera100:1dynamicrange(-2Vpeakto-20mVpeak) for these shaping methods in turn was found to be ± 175 ps, ± 150ps , ± 150 ps and ± 185 ps, respectively. Timing jitter performance with a minimum input signal (-20 mVpeak) in rms units for the four methods in turn were 65 ps, 85 ps, 100 ps and 65 ps. The average power dissipated per CFD channel was found to be approximately 12 mW.

Plume location and prediction using mobile sensors is the main contribution of this thesis. Plume concentration values measured by chemical sensors at different locations are used to estimate the source of the plume. This is achieved by employing a stochastic approximation technique to localize the source and compare its performance to the nonlinear least squares method. The source location is then used as the initial estimate for the boundary tracking problem. Sensor measurements are used to estimate the parameters and the states of the state space model of the dynamics of the plume boundary. The predicted locations are the reference inputs for the LQR controller. Measurements at the new locations (after the correction of the prediction error) are added to the set of data to refine the next prediction process. Simulations are performed to demonstrate the viability of the methods developed. Finally, interpolation using the sensors locations is used to approximate the boundary shape.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 59-61). Also available in electronic version. Access restricted to campus users.

This thesis discusses DC and AC transport properties of molecular devices from first principles. For dc bias, based on the non-equilibrium Green’s function (NEGF) technique coupled with the density functional theory (DFT), the dc current density distribution of a molecular device Al-C60-Al is numerically investigated from first principles. Due to the presence of non-local pseudo-potential, the conventional definition of current density is not suitable to describe the correct current density profile inside the molecular device. By using the new definition of current density which includes the contribution due to the nonlocal potential, our numerical results show that the new definition of current density J(r) conserves the current. In addition, the current obtained from the current density calculated inside the molecular device equals to that calculated from the Landauer-Büttiker formula. When the external bias is time dependent, a theoretical formalism to study the time dependent transport behavior of molecular device from first principles is proposed based on the non-equilibrium Green’s function (NEGF) and time dependent density functional theory (TDDFT). For the purpose of numerical implementation on molecular devices, a computational tractable numerical scheme is discussed in detail. The transient current of two molecular devices Al-1,4-dimethylbenzene-Al and Al-Benenze-Al are numerically studied from first principles. To overcome the computational complexity due to the memory term, a fast algorithm has been employed to speed up the calculation and CPU time has been reduced from the scaling N^3to N^2 log(_2^2)(N) for the step like pulse, where N is the number of time step in the time evolution of Green’s function. / published_or_final_version / Physics / Doctoral / Doctor of Philosophy

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