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Applications that require digital signal processing DSP) functions are typically mapped onto general purpose DSP processors. The FREEDOM compiler has been developed to automatically translate software binary codes targeted for general DSP processors into Register Transfer Level VHDL or Verilog code to be mapped onto commercial FPGAs. This dissertation describes numerous compiler optimizations to translate software binaries to hardware. We describe novel algorithms for pipelining software loops considering the circular dependency and memory life-time holes from software binaries for efficient hardware implementation. We develop sophisticated algorithms for converting sequential algorithms into streaming algorithms. We create a set of stream descriptors to describe the stream patterns from ordinary programs. The stream operations are introduced to compare the streaming relationship between producer-consumer kernels. The hierarchical algorithm identifies the streaming relationships and constructs streaming architectures. We evaluate our algorithms on complex DSP and communication benchmarks. Results indicate speedups of 1.4x for the software pipelining over the non-pipelined design, and speedups of 1.2x–8x for the streaming architectures over the non-streaming ones. The experimental results show that the software pipelining and streaming algorithms presented in this dissertation are efficient methods for improving the parallelism in the binary-to-hardware translation. |
Feb
22
Compiler optimization for translating software binaries onto FPGAs
Feb
22
Functional Fourier-domain optical coherence tomography for guiding vitreoretinal surgery
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Vitreoretinal surgery describes various invasive ophthalmologic procedures to treat a wide range of retinal diseases that leads to blindness. The main hypothesis behind this thesis is that optical coherence tomography OCT) can be used to effectively guide microscopic retinal surgery. Anatomical and functional OCT images can be used to guide surgeons maneuver in real-time to reduce hemorrhaging and detect blood oxygen saturation level SO2) intraoperatively. A fiber-optic spectral domain OCT SD OCT) has been constructed and evaluated in this dissertation research. Advanced signal processing algorithms for OCT have been developed to overcome problems inherently associated with the hardware and the basic signal processing methods. First, to achieve high axial resolution and accurate ranging, a new automatic spectral calibration ASC) method for SD OCT was proposed and validated. Secondly, to reduce speckle noise and simultaneously suppress sidelobes in OCTs point spread function PSF) induced by spectral ripples in the broadband source, an algorithm that combines speckle reduction and deconvolution was developed and the effectiveness of the algorithm was demonstrated. Thirdly, to reduce the amount of data required for high-resolution image reconstruction, the feasibility of using compressed sensing CS) in SD OCT was studied. In this dissertation, another important application of OCT is the detection of microvasculature. Chick chorioallantoic membrane with vessel network was used as model tissue. The location and the dimension of blood vessel was identified from OCT image based on signal intensity, as well as interframe speckle variance. Moreover, a technique known as spectroscopic OCT SOCT) was used to reveal the spectral modification to the incident light induced by blood absorption to assess blood oxygenation level. Finally, speckle variance OCT and spectroscopic OCT images were combined and overlaid to show the locations of blood vessels and spectroscopic information simultaneously. |
Feb
22
Implementation of a Mobile Data Collector in Wireless Sensors Networks for Energy Conservation
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A Wireless Sensor Network (WSN) is composed of low-cost electronic devices with sensing, data storage and transmitting capabilities, powered by batteries. There are extensive studies in the field of WSN investigating different algorithms and protocols for data collection. A data collector can be static or mobile. Using a mobile data collector can extend network lifetime and can be used to collect sensor data in hardly accessible locations, partitioned networks, and delay-tolerant networks. The implementation of the mobile data collector in our study consists of combining two different platforms: the Crossbow sensor hardware and the NXT Legos. We developed an application for data collection and sensor querying support. Another important contribution is designing a semi-autonomous robot control. This hardware prototype implementation shows the benefits of using a mobile data collector in WSN. It also serves as a reference in developing future applications for mobile WSNs. |
Feb
22
Microorganism removal by conventional wastewater treatment process and membrane bioreactor
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Efficacy of conventional wastewater treatment process and the membrane bioreactor technology in removing microbial pathogens was investigated. Total and fecal coliforms, somatic and F-specific coliphages were used as indicators of pathogenic bacteria and viruses. Up to 5.7 logs removal of coliforms and 5.5 logs of coliphages were observed in the conventional treatment process. Addition of chemical coagulants improved the efficacy of primary and secondary treatment for microorganism removal. Complete removal of coliforms and up to 5.8 logs removal of coliphages was observed in the MBR system. It was shown that the MBR system was capable of high removal of coliphages despite the variation in feed coliphage concentrations. The results of this study indicated that the MBR system can achieve better microbial removal by far fewer steps than the conventional treatment process with advanced tertiary treatment. The final effluent from both treatment processes have high quality which potentially can be reused. |
Feb
22
Computational complexity of automatic structures
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This dissertation creates automatic structures with complex recursion-theoretic properties. A structure is said to be automatic if its universe and relations can be recognized by a deterministic finite automaton. Although arbitrary computable structures isomorphic to an automatic structure can be surprisingly complicated, automatic copies require only a few extra conditions to be computably isomorphic to each other. The first section provides definitions and theorems necessary for creating the structures and proving their properties. The second section presents a family of automatic linear orderings, then defines a corresponding family of automatic relations on these structures which appear at arbitrarily high finite levels of the arithmetical hierarchy. The third section creates an automatic equivalence structure, and proves that the set of isomorphic equivalence structures is as complicated as any set of isomorphic equivalence structures can be. The fourth section defines a generalization of equivalence structures, called nested equivalence structures. It goes on to produce an automatic nested equivalence structure for which the set of isomorphic structures is more complicated than any set of isomorphic equivalence structures. The fifth provides brief descriptions of other projects the author assisted during his time at Notre Dame, as well as suggestions for future work on related problems. |
Feb
22
Structural characterization of alkaline hydrogen peroxide (AHP) pretreated biomass
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Alkaline hydrogen peroxide (AHP) pretreatment is exceptionally well-suited to grasses, yielding high digestibilities at low enzyme loadings, while generating relatively few fermentation inhibitors. For AHP pretreatment, the question of how structural and chemical compositional changes within the plant cell wall correlate to pretreatment effectiveness has not been effectively resolved, while knowledge of how selective modification of lignin during pretreatment may improve digestibility may yield insights into both improving pretreatments and tailoring plant cell walls for deconstruction. This study presents a comprehensive chemical and structural characterization of the changes in plant cell walls associated with switchgrass (Panicum virgatum cv. Cave-In-Rock), corn stovers (a commercial hybrid and inbred brown midrib lines bm1 and bm3) and sugar maple (Acer saccharum) and that were AHP pretreated at varied severities. Both the remaining solids and solubilized biomass hydrolysates were subjected to a number of characterizations including total polysaccharide composition, lignin content as both Klason and acetyl bromide lignin, and the ratio of H/G/S monolignols as determined by thioacidolysis GC/MS. Solid-state 13C CP/MAS NMR and HSQC 2D NMR were applied to determine changes associated with intra-lignin, carbohydrate-carbohydrate, carbohydrate-lignin linkages and functional groups. Apparent molecular weight distributions of soluble polymeric lignins and hemicellulose aggregates were determined by HP-SEC. Pyrolysis-GC/MS was utilized to characterize changes in the volatilized compounds before and after pretreatment implying pretreatment-induced alterations in pyrolysis-labile monolignol linkages. |
Feb
22
Design and analysis of an active integrated antenna
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In this thesis, an active integrated antenna AIA) system is proposed for potential applications in an RF receiver front end for mobile and wireless communication devices. The AIA system consists of a microstrip patch antenna and a low noise amplifier LNA), which are integrated together with a matching circuit and printed on an FR4 PCB circuit board. The system is designed, analyzed, and optimized by targeting to satisfy the design specifications for both the microstrip antenna and the LNA in referencing the published industrial parameters. Firstly, the microstrip patch antenna is designed and simulated by the inset feeding method using Agilent ADS software. The optimized dimensions of the square patch are 1000mil x 670 mil with the two smaller feeding patches 400mil x 450mil). The center frequency of the system is 2.45GHz. The objective of this part is to design the antenna to be suitable for wireless communications characterized with low cost, easy fabrication, small size, and high efficiency. Then, the LNA low-noise amplifier), composed of NE68030 NPN silicon transistor, bias circuit, and noise matching network, is also studied and designed. It is connected to the microstrip patch antenna to amplify the signal without adding additional noise. The target of this design is to ensure the LNA to be with high gain, low noise, high efficiency, low cost, and to match well with the receiver antenna. Finally, the microstrip patch antenna and the LNA are integrated together in both the schematic circuit and layout circuits. The integrated AIA system is further tuned and optimized for improving the system performance. The achieved results are encouraging and satisfying and the proposed specifications are essentially met, although the AIA system may be further improved with consideration of industrial design standards. |
Feb
22
Factors limiting biodegradation of the Exxon Valdez oil spill and feasibility of the bioremediation techniques
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The oil from the Exxon Valdez incident is still observed in different Prince William Sound beaches over two decades. The persisting oil is slightly weathered and highly toxic to the environment. Several studies investigated the reasons for lingering oil. Different remediation techniques were tried and the results were not satisfactory. Recently, it was found that the oil is stranded in a low permeability layer. Detailed explorations showed that the exchange of the nutrients and oxygen is limited in this layer. The main objective of the present study is to explain the effect of oxygen and nutrients on the degradation phenomena in the Alaskan beaches. The general approach for this study is a combination of the field experiments and lab analysis. As it is important to eliminate any cross-layer contamination, a unique sampling method was developed. The applied method involves collecting samples from the oily layer low permeability layer), measuring oxygen levels in the field and comparing them with the nutrient samples analyzed in the lab. The findings showed that the nutrients levels were low in the beach but the lack of effective electron acceptor is the major factor limiting the biodegradation of the oil. The seawater is responsible for delivering the oxygen and nutrients to the beach during the high tide while during low tide the landward freshwater discharges to the beach. The study of the sulfate and nitrate in the beach revealed that the levels of the alternative electron acceptors were not sufficient to support anaerobic biodegradation. Finally, for ii successful biodegradation of the Exxon Valdez oil, adequate levels of nutrients nitrogen and phosphorous) and along with oxygen are required. |
Feb
22
System modeling and control design of a two-stage metering poppet-valve system
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The goal of this work is to develop mathematical models, stability criteria, and control designs for a two-stage poppet valve system with a simple back-side pipeline condition that may be used in a valve stack to create an independent metering function for a hydraulic circuit. First, this system is modeled as a nonlinear open-loop model as well as a linear one. The completely linear form of the flow force acting on the poppet head is derived from simplified Navier-Stokes Equations. Second, four control methods that comprise modified PI control, LQG control, Hinfinity control, and nonlinear feedback control are used to make a closed-loop poppet system. The first three linear controllers are verified by being combined with the linear system as well as the nonlinear system in the simulation. The nonlinear controller is only applied to the nonlinear system and certified by Lyapunov theorem to be globally asymptotically stable. The basic guidelines for selecting control gains are derived by Routh-Hurwitz method. Finally, important system parameters are discussed to reveal their effects on the open-loop system stability. The transient flow force and two leakages have very close relationships with the system stability. Simulations results illustrate that the closed-loop poppet system with either the modified PI controller or the nonlinear controller can track the desired poppet displacement represented by a sine wave with 10 HZ frequency. The LQG controller and the Hinfinity controller having fixed weighting functions or matrices are not flexible enough to satisfy the global nonlinear systems, though they exhibit the acceptable regulation behavior. |
Feb
22
A QoS capable architecture for IEEE 802.11 wireless LAN and the prototype implementation on Linux
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The increasing popularity of wireless handheld devices with multimedia functionality and IEEE 802.11 based network connectivity generated the need for Quality of Service QoS) support of real time applications deployed over the wireless LANs. However, the time varying nature of wireless link and network is a serious challenge when attempting to provide Quality of Service support. This thesis proposes a low cost/complexity QoS capable wireless LAN architecture. We designed a distributed network congestion control scheme based on current commercial available hardware. The proposed technique was implemented on a Linux based testbed. Its performance was assessed through extensive experiments. Our evaluation test work includes two parts. First an IEEE802.11b wireless LAN testbed is established and a thorough network capacity measurement test is performed. The actual performance of real wireless LAN products is evaluated in a typical indoor environment. Furthermore, the impacts of multiple competing stations and nearby radio noise are also evaluated in this testbed. In the second part, the QoS capable wireless architecture prototype is implemented using Linux operating system Redhat 7.3 and Orinoco Golden IEEE802.11b wireless network card. The performance evaluation is conducted using the prototype implemented on the IEEE802.11 b wireless LAN testbed. |