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Articles 1 - 16 of 16
Full-Text Articles in Engineering
A Provacative Test To Determine Brain Compliance In The Management Of Patients With Hydrocephalus, Preston K. Manwaring
A Provacative Test To Determine Brain Compliance In The Management Of Patients With Hydrocephalus, Preston K. Manwaring
Theses and Dissertations
Non-invasive techniques to explore intracranial compliance and pressure have been extensively explored in recent years. Previous techniques have used expensive technologies to make these measurements, often with difficulty. We present a novel, inexpensive provocative test to observe trends in intracranial compliance measurement targeted towards the treatment and management of hydrocephalus. Two techniques are proposed which derive data from the digital and supraorbital arteries as well as tympanic membrane displacement. This requires the use of two photo-plethysmographic sensors and a TMD sensor. A common tilt table apparatus is used to methodically and artificially increase intracranial pressure to stress the cranial system …
High Voltage Analog Design In A Standard Digital Cmos Process, Riley D. Beck
High Voltage Analog Design In A Standard Digital Cmos Process, Riley D. Beck
Theses and Dissertations
This thesis introduces high-voltage approaches that are implemented in an analog Hall-effect sensor interface. This interface has been realized in a modified 5V 0.6um CMOS process using 40V high-voltage MOS transistors that do not affect low-voltage device functionality. These circuits include a high-voltage, low-offset current sense amplifier, which achieves a common-mode input range that is within a Vtp of Vdd using a bulk-driven differential input stage. The amplifier also uses high voltage cascode devices to protect low-voltage devices that have been placed in critical matching areas to achieve a low input offset voltage of 500uV without the use of trim. …
Array Analysis Of Radio Frequency Interference Cancelation Requirements For A Land Mine Detection System, Devin Baker Pratt
Array Analysis Of Radio Frequency Interference Cancelation Requirements For A Land Mine Detection System, Devin Baker Pratt
Theses and Dissertations
Land mines are a major humanitarian problem with millions of active mines in place around the world. Since these mines can have little metal in them, novel detection techniques are needed. Nuclear Quadrupole Resonance (NQR) is one such technique. Unfortunately, NQR is highly succeptible to radio frequency interference (RFI). A significant contribution of this thesis is the development of a custom, experimental data acquisition system designed and built specifically for capturing RFI at frequencies significant to NQR land mine detection systems. Another major contribution is the development of data analysis techniques for determining the number of reference antennas required to …
The Development Of A Small Scale Radio Astronomy Image Synthesis Array For Research In Radio Frequency Interference Mitigation, Jacob L. Campbell
The Development Of A Small Scale Radio Astronomy Image Synthesis Array For Research In Radio Frequency Interference Mitigation, Jacob L. Campbell
Theses and Dissertations
Radio astronomy synthesis imaging arrays are composed of many parabolic reflector antennas. These antennas are designed to be extremely sensitive to detect faint emissions from astronomical sources. Unfortunately, this also makes them susceptible to radio frequency interference (RFI) from man made sources such as orbiting satellites. The radio astronomy research group at Brigham Young University (BYU) is investigating methods to mitigate the effects of RFI in radio astronomy synthesis imaging. Though real-time RFI mitigation has been demonstrated for a large single dish telescope, for synthesis imaging arrays our prior work has consisted solely of algorithm development and computer simulations. To …
The Impact Of Antenna And Rf System Characteristics On Mimo System Capacity, Matthew Leon Morris
The Impact Of Antenna And Rf System Characteristics On Mimo System Capacity, Matthew Leon Morris
Theses and Dissertations
The recent growth in demand for wireless services coupled with the limited spectrum available for these services has spawned new efforts to increase the spectral efficiency of wireless links. Recent research has shown that in multipath propagation environments, the spatial characteristics of the propagation channel can be exploited to increase spectral efficiency through the use of multiple antennas at the transmitting and receiving nodes. Such multiple-input multiple-output (MIMO) systems show promise for dramatic performance gains over their single-antenna counterparts. However, MIMO system performance is influenced by many different factors. Antenna array configuration directly contributes to MIMO system performance. The ability …
Reduced Complexity Detection Methods For Continuous Phase Modulation, Erik Samuel Perrins
Reduced Complexity Detection Methods For Continuous Phase Modulation, Erik Samuel Perrins
Theses and Dissertations
Continuous phase modulation (CPM) is often plagued by high receiver complexity. One successful method of dealing with this is the well-known pulse amplitude modulation (PAM) representation of CPM, which was first proposed by Laurent. It is shown that the PAM representation also applies to multi-h CPM and ternary CPM, two previously unconsidered cases. In both cases it is shown that many PAM components may be required to exactly represent the signal. This is especially true of partial-response systems where the memory of the signal is long. Therefore, approximations are proposed which require only a limited number of terms. These extensions …
A Flexible Infrastructure For Multi-Agent Systems, Gerrit Addison N Sorensen
A Flexible Infrastructure For Multi-Agent Systems, Gerrit Addison N Sorensen
Theses and Dissertations
Multi-Agent coordination and control has been studied for a long time, but has recently gained more interest because of technology improvements allowing smaller, more versatile robots and other types of agents. To facilitate multi-agent experiments between heterogeneous agents, including robots and UAVs, we have created a test-bed with both simulation and hardware capabilities. This thesis discusses the creation of this unique, versatile test-bed for multi-agent experiments, also a unique graph creation algorithm, and some experimental results obtained using the test-bed.
A Pam Decomposition Of Weak Cpm, Mason B. Wardle
A Pam Decomposition Of Weak Cpm, Mason B. Wardle
Theses and Dissertations
The Enhanced Flight Termination System uses weak CPM as its modulation scheme and a limiter-discriminator as its demodulation scheme. A PAM representation of weak CPM was developed which representation provided the necessary componenents to build a simplified PAM-based receiver that outperformed the EFTS limiter-discriminator, even in the presence of phase noise. The PAM representation also provided a new perspective into the negative characteristics of weak CPM.
The Hybrid Architecture Parallel Fast Fourier Transform (Hapfft), Joseph M. Palmer
The Hybrid Architecture Parallel Fast Fourier Transform (Hapfft), Joseph M. Palmer
Theses and Dissertations
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. …
Higher Radix Floating-Point Representations For Fpga-Based Arithmetic, Bryan Christopher Catanzaro
Higher Radix Floating-Point Representations For Fpga-Based Arithmetic, Bryan Christopher Catanzaro
Theses and Dissertations
Field Programmable Gate Arrays (FPGAs) are increasingly being used for high-throughput floating-point computation. It is forecasted that by 2009, FPGAs will provide an order of magnitude greater sustained floating-point throughput than conventional processors. FPGA implementations of floating-point operators have historically been designed to use binary floating-point representations, as do general purpose processors. Binary representations were chosen as the standard over three decades ago because they provide maximal numerical accuracy per bit of floating-point data. However, the unique nature of FPGA-based computation makes numerical accuracy per unit of FPGA resources a more important measure of the usefulness of a given floating-point …
Estimating The Dynamic Sensitive Cross Section Of An Fpga Design Through Fault Injection, Darrel E. Johnson
Estimating The Dynamic Sensitive Cross Section Of An Fpga Design Through Fault Injection, Darrel E. Johnson
Theses and Dissertations
A fault injection tool has been created to emulate single event upset (SEU) behavior within the configuration memory of an FPGA. This tool is able to rapidly and accurately determine the dynamic sensitive cross section of the configuration memory for a given FPGA design. This tool enables the reliability of FPGA designs and fault tolerance schemes to be quickly and accurately tested. The validity of testing performed with this fault injection tool has been confirmed through radiation testing. A radiation test was conducted at Crocker Nuclear Laboratory using a proton accelerator in order to determine the actual dynamic sensitive cross …
A Flexible Circuit-Switched Communication Network For Fpga-Based Soc Design, Clint Richard Hilton
A Flexible Circuit-Switched Communication Network For Fpga-Based Soc Design, Clint Richard Hilton
Theses and Dissertations
As FPGA densities continue to improve, single chips are becoming capable of implementing larger and more complex systems. Even today these systems may include several processors working in conjuction with a handful of other standard interfaces or custom modules. Additional system complexity naturally leads to added complexity throughout the different design and implementation stages. Attempting to design such a system while maintaining high performance and within a reasonable time frame is becoming more and more difficult. Architectural design approaches ranging from direct module interconnection to sophisticated bus schemes have been used to build such systems, all with their own trade-offs. …
Equalization Techniques For Multipath Mitigation In Aeronautical Telemetry, Vladimir Ignacio Paje
Equalization Techniques For Multipath Mitigation In Aeronautical Telemetry, Vladimir Ignacio Paje
Theses and Dissertations
This thesis describes the application of adaptive equalization based on the constant modulus algorithm (CMA) and the decision-feedback minimum mean squared error (DF-MMSE) concept to the two compatible offset QPSK waveforms (FQPSK and SOQPSK-TG) that constitute the ARTM Tier-1 waveforms. An adaptive version of the DF-MMSE equalizer is developed and applied to this application. In the presence of frequency selective multipath interference typically encountered in aeronautical telemetry, both equalization techniques are shown to provide reliable performance for FQPSK and SOQPSK-TG. The performance of both waveforms with the DF-MMSE equalizer is slightly better than that using the CMA equalizer. Implementation trade-offs …
Structure From Motion Using Optical Flow Probability Distributions, Paul Clark Merrell
Structure From Motion Using Optical Flow Probability Distributions, Paul Clark Merrell
Theses and Dissertations
Several novel structure from motion algorithms are presented that are designed to more effectively manage the problem of noise. In many practical applications, structure from motion algorithms fail to work properly because of the noise in the optical flow values. Most structure from motion algorithms implicitly assume that the noise is identically distributed and that the noise is white. Both assumptions are false. Some points can be track more easily than others and some points can be tracked more easily in a particular direction. The accuracy of each optical flow value can be quantified using an optical flow probability distribution. …
In-Fiber Optical Devices Based On D-Fiber, Kevin H. Smith
In-Fiber Optical Devices Based On D-Fiber, Kevin H. Smith
Theses and Dissertations
This dissertation presents the fabrication and analysis of in-fiber devices based on elliptical core D-shaped optical fiber. Devices created inside optical fibers are attractive for a variety of reasons including low loss, high efficiency, self-alignment, light weight, multiplexibility, and resistance to electromagnetic interference. This work details how D-fiber can be used as a platform for a variety of devices and describes the creation and performance of two of these devices: an in-fiber polymer waveguide and a surface relief fiber Bragg grating. In D-fiber the core is very close to the flat side of the ‘D’ shape. This proximity allows access …
An Analysis Of Seawinds Simultaneous Wind/Rain Retrieval In Severe Weather Events, Jeffrey R. Allen
An Analysis Of Seawinds Simultaneous Wind/Rain Retrieval In Severe Weather Events, Jeffrey R. Allen
Theses and Dissertations
Scatterometers, such as SeaWinds, can provide wide coverage of ocean surface winds. They estimate near-surface wind vectors by relating measured radar backscatter to a geophysical model function. However, SeaWinds measurements are also sensitive to rain, and conventional wind retrieval degrades in rainy conditions. An algorithm that exploits SeaWinds' sensitivity to both wind and rain has be developed. This algorithm, termed simultaneous wind/rain retrieval, retrieves both wind vectors and rain rates for a given ocean area. Instantaneous results of simultaneous wind/rain retrieval in Hurricane events is analyzed through comparison with the NEXRAD ground-based radar system. This comparison allows validation of retrieved …