Browsing by Subject "Department of Electrical and Computer Engineering"

Now showing 1 - 20 of 22
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    Analysis of Turbostatic Graphene grown using chemical vapor deposition of Acetylene on Sapphire
    (2011-04-13) Kelly, Priscilla; Rothwell, Sara; Cohen PhD, Philip I
    Growing graphene on sapphire (Al2O3) by chemical vapor deposition (CVD) of acetylene is thought to introduce less strain on the bonds of graphene compared to other CVD methods. This is due to coincidence lattice matching in sapphire's hexagonal structure that appears after annealing. At this stage of my research, we are testing deposition rates of graphene on sapphire which has led to turbostratic, random and disorganized, growth. This poster demonstrates the properties of our turbostratic graphene from data collected by Raman spectroscopy, Scanning Electron Microscopy (SEM), sheet resistance measurements, and optical imaging.
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    Can You Hear Me Now? Solving the Headphone Problem
    (2009-04-08) Hornung, Stephanie; Evenson, Maureen; Pope, Zach; Olson, Kyle; Cook, David
    This project will develop a product that will be embedded into headphones to prevent the wearer from missing essential communication, either from conversation or emergency sirens (fire alarms, tornado sirens, emergency vehicle sounds, etc.). It will monitor ambient sound and determine whether or not music should be interrupted. A microphone will pick up sound from the environment, then analysis software will process it to determine the next step. If the sound is determined to be either close range human speech or an emergency siren, the code will signal the music to cease. If neither of these is recognized, the music will continue. The bulk of the project lies in developing software that can differentiate human speech from other ambient sounds. Thus far, we are writing code and figuring out what distinguishes human speech from other ambient noise. This includes spectrogram analysis of various sound recordings. From our research, we know that we must analyze each sound to approximately 1/100th of a second (this is defined to be a "feature"). Each feature is assigned a probability that it appears as a portion of a spoken word. We cross-reference each probability with 1000's of feature charts of recognizable human speech patterns to determine if the sound is from a human voice. Based on this probability, we decide if the word is human speech. The code we create to do this will be transferred to a pic microcontroller, which interfaces with the microphone and the music player, allowing it to quickly respond to human speech or emergency signals.
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    CMOS Operational Amplifier
    (2011-08-11) Wood, Sam
    An operational amplifier (op-amp) is a voltage amplifier with a differential input and a single-ended output. Op amps are important building blocks for a wide range of electronic circuits. They are among the most widely used electronic devices today, being used in a large array of consumer, industrial, and scientific devices. They may be packaged as components, or used as elements in complex integrated circuits.
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    Design of MTJ-Based Spintronic Logic
    (2009-04-08) Ebrahimi, Farbod
    The very first transistor was made in 1947 and it has only been 62 short years since its invention. During this time technological advances have made great leaps and bounds and they all owe this to the transistor. Advancements are nearing a plateau as the technology to build transistors reaches its physical limits, and as such, a new component needs to be introduced that can pass the limitations of the transistor. A great candidate is the magnetic-tunneling-junction (MTJ), and only then as a replacement for the transistors digital applications. Already there are many groups designing it physically and finding the best method of production as well as many groups using them to replace transistors in circuits. Thus far, there haven't been any definitive models made of this device to allow simulations of theorized circuits, and the goal of my project since September 2008 has been not only to create a model for the MTJ to use in simulations, but to also simulate a select few theorized circuits to demonstrate the benefit of using MTJ's over transistors. Hopefully through these models and simulations, more innovative designs can come out as they did with the transistor and help keep the pace of our technological advancement to help build better futures for all of us who are alive today, and those who are yet to come into this world.
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    ECE Circuit Board (1997 Fall)
    (University of Minnesota, Duluth, 1997) University of Minnesota, Duluth. Department of Electrical and Computer Engineering
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    ECE Circuit Board (2000 Fall)
    (University of Minnesota Duluth, 2000) University of Minnesota Duluth. Department of Electrical and Computer Engineering
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    ECE Circuit Board (2006 Fall)
    (University of Minnesota Duluth, 2006) University of Minnesota Duluth. Department of Electrical and Computer Engineering
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    ECE Circuit Board (2006 Spring)
    (University of Minnesota Duluth, 2006) University of Minnesota Duluth. Department of Electrical and Computer Engineering
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    ECE Circuit Board (2007 Fall)
    (University of Minnesota Duluth, 2007) University of Minnesota Duluth. Department of Electrical and Computer Engineering
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    ECE Circuit Board (2007 Spring)
    (University of Minnesota Duluth, 2007) University of Minnesota Duluth. Department of Electrical and Computer Engineering
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    ECE Circuit Board (2008 Fall)
    (University of Minnesota Duluth, 2008) University of Minnesota Duluth. Department of Electrical and Computer Engineering
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    ECE Circuit Board (2009 Fall)
    (University of Minnesota Duluth, 2009) University of Minnesota Duluth. Department of Electrical and Computer Engineering
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    Implementing a Randomized Algorithm for the Graph Partitioning Theory
    (2009-04-08) Schoppe, Dan M.
    Many existing algorithms use the divide-and-conquer paradigm to partition a large problem into smaller sub-problems to reduce time complexity and provide better solutions. One application would be used to divide one large VLSI circuit design into two more manageable pieces in order to manufacture the design into integrated circuit packages. Even though there have been attempts on implementing parallel versions of these algorithms in software, no serious attempt has been made to design hardware implementations of these algorithms. A promising approach to harness the power of FPGAs for complex algorithms is the use of randomized algorithms. By using a randomized "guess-and-check" process called the Monte Carlo method to find optimal partitioning solutions, this project aims to improve upon existing software partitioning algorithms. An FPGA will provide random numbers at the bit-by-bit level. A PowerPC will make use of these random numbers to divide the VLSI design into two distinct parts. After thousands of iterations and potential solutions, the best solution is retained for use. The hope is that guessing at a solution thousands of times could be a better method of optimization than running a complex algorithm.
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    Integrated Surface Acoustic Wave Device on an Aluminum Nitride Wafer
    (2011-08-11) Ramirez, Johnny
    Surface acoustic wave (SAW) devices are essential for many signal processing applications, ranging from filtering a signal, creating a device for military use, or using them to create a cell phone with better reception. Surface acoustic waves are generated by applying an electric signal to a piezoelectric substrate, which then turns the electric signal into an acoustic wave. SAW devices contain rectangular-looking figures known as interdigital transducers, essential for converting the acoustic wave back into an electric signal at the output. Therefore, two SAW devices are required for this effect to occur. The piezoelectric substrate used in this project is Aluminum Nitride (AlN), which allows the user to send a high frequency to the SAW device and operate at high temperatures.
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    Lossless Holographic Spectrum Splitter In Lateral Photovoltaic Devices
    (2011-11) Lin, Di; Torrey, Ethan R.; Leger, James R.; Cohen, Phil. I.
    Lateral photovoltaic structures require efficient partitioning of the solar spectrum and light delivery to the respective cells. Single-junction cells can be used, eliminating the need for current and lattice matching. We investigate the design issues associated with multiplexed volume holograms in fulfilling this role in a two-cell lateral PV system.
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    Multivariable Analysis of Hard Anodization
    (2009-10-07) Norby, Gregory
    Anodized Aluminum Oxide (AAO) nanopores are used as molds in the electrodeposition of metal nanowires. The diameter of the pores can greatly affect the wires’ properties. The Hard Anodization (HA) method was employed: higher 2nd anodization voltage, faster sample production. The 1st and 2nd anodization steps were analyzed: powerful effect on diameter, relative lack of understanding of their effect with HA.
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    Numerical Simulations on Microwave Assisted Magnetic Recording (MAMR)
    (2009-04-08) Stoll, Casey M.
    Computer hardware continues to shrink every year, and magnetic hard drives are no exception. In January of 2009, Western Digital released the first 2-terabyte drive. High data density is very important for data centers where size, heat, and power are key. My research investigates a method of writing magnetic recording media that some believe promises even higher densities. Through the use of a computer simulated model of a single magnetic grain or "bit," I was able to observe the effect of a circularly polarized, microwave frequency magnetic field on the switching behavior of a bit. By taking advantage of the microwaves, I was able to design a grain system that can be made smaller while still maintaining resistance to thermal noise. To do this, I optimized various parameters of a multilayer composite recording media model that, in conjunction with the microwaves, allows for a decrease in minimum switching magnetic field magnitude of about 30%.
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    Parasitic resistance effects of split-spectrum solar cell performance
    (2010) Krohn, Jennifer; Ruden, Paul
    Semiconductor solar cells absorb photons of energy greater than their band-gap and convert the photon energy to electrical energy less than the band-gap. Consequently, small gap solar cells can absorb a large part of the solar spectrum, but deliver little energy per photon absorbed. Large gap solar cells deliver more energy per photon, but can absorb only the high energy part of the spectrum. Splitting the solar spectrum into multiple segments with diffractive elements that separate the incident radiation spatially and focusing it on solar cells optimized for the narrower bands facilitates the energy conversion. Here, we explore limitations to this approach imposed by inevitable parasitic effects. Specifically, we introduce series and parallel resistances into an ideal solar cell model. Resistance of the cell material and the contacts, and current leakage through the junction, due to defects, can be captured by this model. Subsequently, current density characteristics, maximum power density, and efficiency are determined. Highly conductive, low band-gap cells show performance degradation due to series resistance, while highly resistive, large gap cells are sensitive to junction leakage. As a specific case, we consider a three-cell solar cell array fabricated from InxGa1-xN of varying composition.
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    Register Machine Computation in Synthetic Biology
    (2010-04-21) Thurmes, Kathleen A.
    The goal of this investigation was to determine whether it would be feasible to use a register machine (RM) computation method to simulate biological functions and, if so, attempt to create a compiler that would automate the process of design. The functions that were chosen for simulation were not meant to represent actual chemical processes that occur in biological systems, but to present a range of very simple functions that could be easily built into a prototype compiler.