Matching Items (188)
Description
In modern remote sensing, arrays of sensors, such as antennas in radio frequency (RF) systems and microphones in acoustic systems, provide a basis for estimating the direction of arrival of a narrow-band signal at the sensor array. A Uniform linear array (ULA) is the most well-studied array geometry in that its performance characteristics and limitations are well known, especially for signals originating in the far field. In some instances, the geometry of an array may be perturbed by an environmental disturbance that actually changes its nominal geometry; such as, towing an array behind a moving vehicle. Additionally, sparse arrays have become of interest again due to recent work in co-prime arrays. These sparse arrays contain fewer elements than a ULA but maintain the array length. The effects of these alterations to a ULA are of interest. Given this motivation, theoretical and experimental (i.e. via computer simulation) processes are used to determine quantitative and qualitative effects of perturbation and sparsification on standard metrics of array performance. These metrics include: main lobe gain, main lobe width and main lobe to side lobe ratio. Furthermore, in order to ascertain results/conclusions, these effects are juxtaposed with the performance of a ULA. Through the perturbation of each element following the first element drawn from a uniform distribution centered around the nominal position, it was found that both the theoretical mean and sample mean are relatively similar to the beam pattern of the full array. Meanwhile, by using a sparsification method of maintaining all the lags, it was found that this particular method was unnecessary. Simply taking out any three elements while maintaining the length of the array will produce similar results. Some configurations of elements give a better performance based on the metrics of interest in comparison to the ULA. These results demonstrate that a sparsified, perturbed or sparsified and perturbed array can be used in place of a Uniform Linear Array depending on the application.
ContributorsSilbernagel, Drake Oliver (Author) / Cochran, Douglas (Thesis director) / Aberle, James (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
This paper reviews several current designs of Cube Satellite (CubeSat) Electrical Power Systems (EPS) based on Silicon FET technologies and their current deficiencies, such as radiation-incurred defects and switching power losses. A strategy to fix these is proposed by the way of using Gallium Nitride (GaN) High Electron-Mobility Transistors (HEMTs) as switching devices within Buck/Boost Converters and other regulators. This work summarizes the EPS designs of several CubeSat missions, classifies them, and outlines their efficiency. An in-depth example of an EPS is also given, explaining the process in which these systems are designed. Areas of deficiency are explained along with reasoning as to why GaN can mitigate these losses, including its wide bandgap properties such as high RDS(on) and High Breakdown Voltage. Special design considerations must be kept in mind when using GaN HEMTs in this application and an example of a CubeSat using GaN HEMTs is mentioned. Finally, challenges ahead for GaN are explored including manufacturing considerations and long-term reliability.
ContributorsWilloughby, Alexander George (Author) / Kitchen, Jennifer (Thesis director) / Zhao, Yuji (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Communication between the physical and digital world via software, embedded sensors and network connectivity is referred to by the term, the "Internet of Things" (IoT) [1]. The IoT transforms natural objects into "smart devices" to improve accuracy, reduce human intervention, and provide real-time data [1]. Smart weather stations that upload information, including temperature and humidity, to the Internet are already available. However, these products are often expensive and programmed only for single-purpose use. The LoRa Weather Station is a low cost, low power and low maintenance IoT solution that combines Microchip Technology's LoRa RN2903 module along with Mikroelektronika's Weather Click sensor. This report discusses how the LoRa Weather Station was created, primarily focusing on the LoRa gateway setup by a Raspberry Pi local web server. This project was completed by four electrical engineering students in the EEE 488 and 489 Senior Design courses at Arizona State University from Fall 2016 to Spring 2017. Total expenses for the project were $717.84, including the LoRa gateway which amounted to $104 (see Appendix C for the Bill of Materials).
ContributorsLeon, Miranda Cristina (Author) / Kozicki, Michael (Thesis director) / Balaban, Mehmet (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Resistive Random Access Memory (RRAM) is an emerging type of non-volatile memory technology that seeks to replace FLASH memory. The RRAM crossbar array is advantageous in its relatively small cell area and faster read latency in comparison to NAND and NOR FLASH memory; however, the crossbar array faces design challenges of its own in sneak-path currents that prevent proper reading of memory stored in the RRAM cell. The Current Sensing Amplifier is one method of reading RRAM crossbar arrays. HSpice simulations are used to find the associated reading delays of the Current Sensing Amplifier with respect to various sizes of RRAM crossbar arrays, as well as the largest array size compatible for accurate reading. It is found that up to 1024x1024 arrays are achievable with a worst-case read delay of 815ps, and it is further likely 2048x2048 arrays are able to be read using the Current Sensing Amplifier. In comparing the Current Sensing Amplifier latency results with previously obtained latency results from the Voltage Sensing Amplifier, it is shown that the Voltage Sensing Amplifier reads arrays in sizes up to 256x256 faster while the Current Sensing Amplifier reads larger arrays faster.
ContributorsMoore, Jenna Barber (Author) / Yu, Shimeng (Thesis director) / Liu, Rui (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Having the proper biomechanical and neuromuscular kinematics while performing an athletic motion is essential for athletes. Deviations from proper form in execution of the kinetic chain of an athletic movement may result in suboptimal performance and oftentimes an elevated likelihood of injury. The solutions currently available to athletes to account for digression from proper form are limited to sight and feel analysis of movement by the athletes and coaches and basic medical and athletic analysis equipment that is unsuitable for real-time analysis, the rigor and speed of dynamic athletic motions, and in-field use. The solution proposed herein is one of an in-shoe force measurement and foot positioning system designed to measure the ground reaction force generated by and alignment of an athlete's feet during an athletic motion. Research into various sports has found that the feet play a foundational role in proper execution of the kinetic chain, wherein the alignment, positioning, force generation, and timing of the feet may dictate proper execution of subsequent segments in the kinetic chain. The goal of the present design is to provide athletes with a solution to allow for real-time kinematic analysis of athletic motions using an in-shoe force measurement and foot positioning system. An understanding into the compensatory effect of foot misalignment, mismatched timing, and under or overcompensated ground reaction force generation by the feet on ensuing segments of the kinetic chain in conjunction with the present design can allow for athletes to measure and determine their degree of accuracy in form execution and to predict potential injuries resulting from deviations in form. Our design of an athletic shoe comprising an in-shoe force measurement system provides a dynamic solution to sports-related injuries presently unavailable to athletes.
ContributorsKiaei, Nima (Co-author) / Makhija, Abhay (Co-author) / Kiaei, Sayfe (Thesis director) / Kozicki, Michael (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Aerogels are among the best known thermally insulating materials due their high porosities (>90%). This, in conjunction with their high transparency make them ideal candidates for highly insulating window coatings. However, current state of the art techniques involve time-consuming drying steps and poor mechanical robustness, severely limiting their wide-scale adaptation. By using a dry aerosol impaction process, synthesizing nanoparticles in a plasma, upstream of a slit-shaped nozzle and impacting these particles onto a substrate below, a novel way for producing mesoporous silica aerogels is shown. This removes the need for solution-based processing, improving the potential for high throughput. Thick (~100um), 90% mesoporous silica has been characterized showing low effective thermal conductivity (~0.02 W/mK) and high transparency (>90%). The morphology of these coatings were analyzed showing tight pore distributions. Film adhesion and stress have shown themselves to be major hurdles during the development of these coatings and will be the focus of future work.
ContributorsRodkey, Nathan Jacques (Author) / Holman, Zachary (Thesis director) / Bryan, Jonathan (Committee member) / Materials Science and Engineering Program (Contributor) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
In this project, an existing waveform generator designed by the vagus nerve stimulation (VNS) technology firm Hoolest Performance Technologies was modified and characterized. Voltage feedback and current feedback systems were designed in order to improve output voltage and current regulation. A wireless communication system was implemented onboard the newly designed waveform generator in order to improve user experience and allow the system to be controlled remotely. Finally, a custom printed circuit board was designed according to the established circuit schematics for the above components, and the layout was miniaturized to a total board footprint area of 1.5 square inches. The completed device was characterized according to several figures of merit including current consumption, voltage and current regulation, and short-circuit behavior.
ContributorsPatterson, John Michael (Author) / Kozicki, Michael (Thesis director) / Mian, Sami (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
This thesis outlines the hand-held memory characterization testing system that is to be created into a PCB (printed circuit board). The circuit is designed to apply voltages diagonally through a RRAM cell (32x32 memory array). The purpose of this sweep across the RRAM is to measure and calculate the high and low resistance state value over a specified amount of testing cycles. With each cell having a unique output of high and low resistance states a unique characterization of each RRAM cell is able to be developed. Once the memory is characterized, the specific RRAM cell that was tested is then able to be used in a varying amount of applications for different things based on its uniqueness. Due to an inability to procure a packaged RRAM cell, a Mock-RRAM was instead designed in order to emulate the same behavior found in a RRAM cell.
The final testing circuit and Mock-RRAM are varied and complex but come together to be able to produce a measured value of the high resistance and low resistance state. This is done by the Arduino autonomously digitizing the anode voltage, cathode voltage, and output voltage. A ramp voltage that sweeps from 1V to -1V is applied to the Mock-RRAM acting as an input. This ramp voltage is then later defined as the anode voltage which is just one of the two nodes connected to the Mock-RRAM. The cathode voltage is defined as the other node at which the voltage drops across the Mock-RRAM. Using these three voltages as input to the Arduino, the Mock-RRAM path resistance is able to be calculated at any given point in time. Conducting many test cycles and calculating the high and low resistance values allows for a graph to be developed of the chaotic variation of resistance state values over time. This chaotic variation can then be analyzed further in the future in order to better predict trends and characterize the RRAM cell that was tested.
Furthermore, the interchangeability of many devices on the PCB allows for the testing system to do more in the future. Ports have been added to the final PCB in order to connect a packaged RRAM cell. This will allow for the characterization of a real RRAM memory cell later down the line rather than a Mock-RRAM as emulation. Due to the autonomous testing, very few human intervention is needed which makes this board a great baseline for others in the future looking to add to it and collect larger pools of data.
The final testing circuit and Mock-RRAM are varied and complex but come together to be able to produce a measured value of the high resistance and low resistance state. This is done by the Arduino autonomously digitizing the anode voltage, cathode voltage, and output voltage. A ramp voltage that sweeps from 1V to -1V is applied to the Mock-RRAM acting as an input. This ramp voltage is then later defined as the anode voltage which is just one of the two nodes connected to the Mock-RRAM. The cathode voltage is defined as the other node at which the voltage drops across the Mock-RRAM. Using these three voltages as input to the Arduino, the Mock-RRAM path resistance is able to be calculated at any given point in time. Conducting many test cycles and calculating the high and low resistance values allows for a graph to be developed of the chaotic variation of resistance state values over time. This chaotic variation can then be analyzed further in the future in order to better predict trends and characterize the RRAM cell that was tested.
Furthermore, the interchangeability of many devices on the PCB allows for the testing system to do more in the future. Ports have been added to the final PCB in order to connect a packaged RRAM cell. This will allow for the characterization of a real RRAM memory cell later down the line rather than a Mock-RRAM as emulation. Due to the autonomous testing, very few human intervention is needed which makes this board a great baseline for others in the future looking to add to it and collect larger pools of data.
ContributorsDobrin, Ryan Christopher (Co-author) / Halden, Matthew (Co-author) / Hall, Tanner (Co-author) / Barnaby, Hugh (Thesis director) / Kitchen, Jennifer (Committee member) / Electrical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
This thesis is a proposition for an addition to an engineering project that involves creating a heads up display for a scuba diving mask which displays important safety information. The premise of this thesis includes three different features: distress, distance, and direction. The distress feature is to alert a diver that their “buddy diver” is having an emergency and is requiring attention. Distance and direction are intended to be included on the heads up display, informing the diver of the relative location of their “buddy diver” in case they have lost sight of them. A set of requirements was created to find the most practical solutions. From these requirements and extensive research, three potential methods of underwater communication were found; electromagnetic waves in the radio frequency range, optical waves, and acoustic waves. Of these three methods, acoustic waves were found to be most feasible for the scope of this project. Using modems and transducers, an acoustic signal is able to be sent from one diver to another in order to detect relative location as well as send a message of distress. Ultimately, two possible concepts were designed, with one deemed as most advantageous. This concept engages the use of four transponders that have the ability to transmit and receive high frequencies, minimizes blind spots, and is small enough to not cause discomfort or be obstructive to the divers experience. Due to the nature of this application, the team is able to propose a path of development for a compact communication system between scuba divers.
ContributorsNossaman, Grace (Co-author) / Hocken, Chase (Co-author) / Padilla, Bryan (Co-author) / Richmond, Christ D. (Thesis director) / Baumann, Alicia (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
This thesis is a proposition for an addition to an engineering project that involves creating a heads up display for a scuba diving mask which displays important safety information. The premise of this thesis includes three different features: distress, distance, and direction. The distress feature is to alert a diver that their “buddy diver” is having an emergency and is requiring attention. Distance and direction are intended to be included on the heads up display, informing the diver of the relative location of their “buddy diver” in case they have lost sight of them. A set of requirements was created to find the most practical solutions. From these requirements and extensive research, three different methods of underwater communication were found, but only one, acoustics, was feasible for the scope of this project. Using modems and transducers, an acoustic signal is able to be sent from one diver to another in order to detect relative location as well as send a message of distress. Ultimately, two possible concepts were designed, with one deemed as most advantageous. This concept engages the use of four transponders that have the ability to transmit and receive high frequencies, minimizes blind spots, and is small enough to not cause discomfort or be obstructive to the divers experience.
ContributorsHocken, Chase (Co-author) / Nossaman, Grace (Co-author) / Padilla, Bryan (Co-author) / Richmond, Christ D (Thesis director) / Baumann, Alicia (Committee member) / Electrical Engineering Program (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05