Now showing items 1-20 of 29

    • Design And Implementation Of A Meteor Tracking Retrofit System For The Hf Radar At Kodiak Island, Alaska

      Parris, Richard Todd; Bristow, William (2003)
      The HF radar at Kodiak Island, Alaska, is part of the SuperDARN network of radars, and was originally designed to detect echoes from ionospheric field-aligned density irregularities. A new digital receiver has been implemented on the radar to allow provide the capabilities required for increased range resolution detection of meteor echoes. A meteor detection algorithm has also been implemented to detect meteor echoes with a range resolution of 4.5 km. The algorithm measures the velocity, range, and altitude of the echoes. This data can be used to derive information about the meteor region winds. The design and implementation of the receiver, the design and implementation of the meteor detection algorithm, and some meteor region wind data derived from the new system are presented. <p>
    • TEST College of Liberal Arts 9/25/17

      CHISUM (2017-09)
      TEST College of Liberal Arts 9/25/17
    • Design and simulation of flight computer using VHDL for ARIM-1 sounding rocket payload

      Chowdhury, Anirban (2000-12)
      Atmospheric Refractive Index Measurement-1 (ARIM-1) is a sounding rocket payload designed to collect information regarding atmospheric turbulence. ARIM-1 is designed to make high-resolution (4 samples per centimeter) differential temperature measurements of the atmosphere to determine the structure of atmospheric turbulence and hence it's refractive index. The rocket's flight computer schedules and manages data acquisition from various payload sub-systems and transmits this acquired data to the ground station. The goal of this work is to develop a custom design for this flight computer using Very High Speed Integrated Circuit Hardware Description Language (VHDL). This thesis presents simulation and hardware requirements for the flight computer generated from a professional Computer Aided Design package used for VHDL design implementation. This thesis proposes a new architecture for the flight computer that can be implemented with Programmable Logic Devices using VHDL.
    • Uncertainty in fish location using a split beam sonar

      Ayers, Mark L. (2001-05)
      The enumeration of fish is of critical importance to the management of both commercial and sport fisheries in Alaska and worldwide. Current methods for riverine fish enumeration are inaccurate and unreliable. Improved fish counting accuracy in Alaskan rivers by acoustic methods is required. A split beam sonar system in the presence of noise is modeled. The sonar system including the received sonar pulse, receiver system, transducer beam pattern, propagation losses, and noise are modeled. An analysis of the effects of noise, pulse duration and sampling frequency on the uncertainty in fish location is presented. Signal to noise ratios less than 5 dB can cause significant errors in the calculation of received signal phase. A stationary fish with a signal to noise ratio of 15 dB has approximately plus-minus 0.001 degrees of uncertainty in the angles of arrival. Reducing the SNR to 3 dB the uncertainty increases to plus-minus 3.6 degrees in the angles of arrival.
    • Study of the performance of a proton exchange membrane fuel cell

      Morgan, Christopher Lee (2000-08)
      As fossil fuels become scarce, finding new sources of efficient, reliable, and renewable power generation is critical. One device being given lots of attention for this purpose is a fuel cell. Fuel cells not only produce electricity, but also heat which can be recovered for residential use and increase the overall system efficiency. Test benches were constructed to measure and record data from fuel cells under a range of electrical loads. Energy balance was constructed to characterize the fuel cell system using experimental data. The energy balance resulted in a first law gross electrical efficiency of over 44 percent and a second law efficiency greater than 52 percent for the opening range of the fuel cell system.
    • Design of circularly polarized, omnidirectional microstrip sounding rocket antennas for telemetry and GPS applications

      Sullins, Ty (2001-08)
      The orientation of a sounding rocket with respect to ground stations or GPS satellites is often highly variable and sometimes unpredictable due to its trajectory and spin. Therefore, a sounding rocket antenna should have a radiation pattern that is nearly omnidirectional to ensure sufficient signal strength in any direction, and the antennas should be circularly polarized to minimize polarization loss. Microstrip antennas are well suited to meet these requirements because they are low profile, lightweight, durable, and can be conformed to nonplanar geometries. Additionally, circularly polarization can be achieved using simple geometries and small size. This dissertation presents the theory and equations required to design common microstrip antennas. Circularly polarized telemetry and GPS antennas are designed for sounding rocket payloads with 6, 8, and 14-inch diameters, and their performance is compared with linearly polarized antennas. A circularly polarized antenna for a 14-inch diameter rocket payload is fabricated and it measured performance compared with theoretical predictions.
    • Design and implementation of a motor controller for a permanent magnet synchronous machine

      Mitchell, Jerias (2000-08)
      This thesis describes the design and implementation of a motor controller for use with a prototype Axial-Gap Permanent-Magnet Synchronous Machine (AGPMSM). The goal of this work is to design a controller to drive an AGPMSM "smart wheel" that will be used in a semiautonomous vehicle. Controllers in this application are typically vector or scalar controllers using a form of Pulse Width Modulated (PWM) sinusoidal control. These types of controllers allow an AC machine to behave as a DC machine, which greatly simplifies the control algorithms and eliminates the need to operate the machine as an induction motor to achieve the desired speed. The advantage of the vector controller over the scalar controller is the ability to run the motor beyond its rated speed. In this design only scalar control is implemented. The controller/motor is semiautonomous in that it only requires an external speed command. The closed loop controller will attempt to maintain that speed, even as the load on the motor changes. The complete design will be described, starting with a functional description and then an overview of the hardware and software design. Some experimental data will be presented to demonstrate a functioning prototype.
    • Scintillation at K-band and Ka-band frequencies

      Kim, Táe-hong (2000-05)
      The need for higher bandwidth and smaller antenna size for satellite communications led NASA to fund the Advanced Communications Technology Satellite (ACTS) and propagation research for K-band and Ka-band frequencies. From December 1993 to December 1998, seven sites in North America have collected and processed power measurements at 20.2 and 27.5 gigahertz from ACTS, a geostationary statellite located at 100 ̊West longitude. The thesis compares scintillation measurements to eight scintillation prediction models, proposes a cumulative distribution model to help predict the percentage of time scintillation exceeds a given threshold, examines the effects of frequency on scintillation magnitudes, and proposes a climate model based on moisture content to help predict scintillation magnitudes. The study concludes that the scintillation prediction models are dependent on the climate, the frequency dependence is a function of climate, and the moisture content in the atmosphere dictates the percentage of time large scintillation occurs.
    • Development of a differential GPS tracking system for sounding rocket payloads

      Helmericks, Jay Gregory (2001-08)
      The purpose of this thesis was to develop a system that could track a sounding rocket payload with a commercial GPS receiver. A GPS receiver was chosen that still outputs raw data when the COCOM limits are exceeded. All the hardware to support the OEM GPS receiver in a reverse differential system was designed and built, including both a ground system and two flight systems to support both on-board storage and telemetry. A software program was developed to archive and compute positions from the raw data. The GPS system has been ground tested and flown on an Orion sounding rocket. The testing shows that the system works and the expected accuracy is 10-50 ft. depending on the distance between the ground station and the rocket, satellite geometry and other sources of error.
    • Design and construction of a low earth orbit satellite ground station

      Darnel, Eric (2000-12)
      This thesis describes the design and construction of a satellite ground station constructed in support of the Citizen Explorer Program. The University of Alaska Fairbanks was chosen to participate in this program due to its latitude that gives it excellent access to polar-orbiting satellites. The advantage that higher latitudes have in accessing low earth orbiting satellites is examined. It is demonstrated that Fairbanks, Alaska, has roughly twice the access to polar orbiting satellites than the mid-latitudes of the contiguous US. Link budgets for the communication system were developed, which led to the construction of helical antennas to communicate with the satellite. Data are presented that demonstrate the antennas, as well as the rest of the satellite tracking system, functioned acceptably. The satellite ground station will provide internet access to the spacecraft. The procedure used to test this approach and its results are given, as well as recommendations for future work.
    • Meteor wind wave analysis of SuperDARN observations

      Dai, Wei (2000-08)
      SuperDARN is an extensive array of radars located in both the northern and southern Auroral regions. The array has been used to study plasma convection in the high-latitude ionosphere. A recent study shows that it can also be used to observe the characteristics of the high latitude mesophere-lower-thermosphere (MLR) region. In this region, noise-like echoes, which show totally different properties from the E or F region irregularities, were paid particular interest in recent studies. The echoes are considered to be due to scatter from meteor trails. In this thesis, an algorithm was designed to extract meteor echoes from the SuperDARN data. The extracted data were then used to determine the time series of the zonal and meridian neutral wind. From the time series, various wave modes have been identified and seasonal behavior of those wave modes were studies.
    • Rayleigh lidar studies of the Arctic middle atmosphere

      Cutler, Laura Jeanette (2000-12)
      Rayleigh lidar allows us to measure density and temperature structure of the atmosphere at heights from approximately 35 to 80 kilometers. A Rayleigh lidar was installed at Poker Flat Research Range in November of 1997 and has been operated routinely since. This thesis presents an engineering analysis of the lidar system performance and a scientific analysis of the data obtained. The engineering analysis considers the receiver and transmitter alignment of the lidar system and the signal quality of the lidar data. The scientific analysis considers the retrieval of density and temperature profiles under a range of geophysical conditions. This study uses a three-year data set that includes 38 nights of data.
    • Leveraging Alaska North Slope satellite oil field design with networked instrumentation and control systems architecture - Foundation Feldbus

      Chouinard, Brian A. (2000-05)
      Since 1988, oil production rates on Alaska's North Slope have faded. The West Sak oil field in the Greater Kuparuk Area was a satellite field targeted to help slow the production decline. The nature of West Sak oil made it prohibitively expensive to produce using conventional methods. Drastic changes in field production design and operational philosophy were required to make West Sak oil economically viable. The instrumentation and controls network architecture leveraged the implementation of this new design and philosophy. This paper examines the technological requirements, establishes evaluation criteria, compares competing options, outlines the design and implementation, and discusses future prospects. In addition, a functional description of the selected technology, Foundation Fieldbus, is presented from the users perspective.
    • Observation and analysis of whistler mode echoes received by RPI on IMAGE at high latitudes

      Chen, Xiangdong (2001-05)
      Whistler-mode wave-injection experiments with Radio Plasma Imager (RPI) on IMAGE offer an opportunity to observe the whistler-mode echoes. We have performed raytracing studies to investigate accessibility of whistler-mode waves injected from IMAGE to various regions of the magnetosphere and also to other satellites such as Akebono. RPI detected both discrete and diffuse whistler-mode echoes during our observing period (April 21 to August 28, 2000) when IMAGE was at a low altitude (1̃000-7000 km) and mid-to-high latitudes (>25 - 40S̊) near its perigee. We believe that the discrete echoes are the result of RPI signals reflected at the Earth-ionosphere boundary and the diffuse echoes are the result of scattering of RPI signals by meter-scale irregularities. Raytracing analysis shows that both ducted and nonducted ray propagation are needed to explain the observed whistler-mode dispersion. Comparison of electron densities obtained from our raytracing analysis of dispersion with the electron densities obtained by Kletzing et al. in the Auroral Zone shows that these density values deduced from RPI data were about ten times higher. This may be because the antenna radiation efficiency is higher at higher electron densities.
    • Uncertainty in fish counting using an echo-counting technique as applied to data from a single-beam sonar

      Lai, Zhiguo (2002-08)
      A model of fish distribution in time and space and a single-beam sonar model are presented. Simulated sonar data are obtained and analyzed using the echo-counting method to determine the estimated number of fish. The results show that (1) when the fish rate is less than 1 fish/s, the error is within plus minus 15% and fish are overcounted more often than undercounted, (2) this method underestimates the number of fish by 57% of the actual number of fish for a fish rate of 5 fish/s, (3) fish counts are dominated by the noise if the threshold is lower than the noise level, (4) by varying the ping rate, the error could be as much as 72% for a fish rate of 10 fish/s and a ping rate of 10 pings/s, (5) by varying the pulse width, the error could be as much as 80% for a fish rate of 10 fish/s and a pulse width of 1.0 ms.
    • Modeling fish movement in sonar beam

      Chen, Biao (2002-05)
      Enumerating salmon in the Yukon River drainage allows for assessment of annual harvest management guidelines and prediction of long-term salmon population trends in Alaska. Sonar is currently used to enumerate migrating salmon and determine salmon location in the river. To understand these results, a model of fish movement is required. This thesis analyzes the existing sonar data on fish movement to construct a model that predicts typical spatial and temporal distribution of fish. A model of the sonar measurement system, which includes target strength, transmission loss, transducer beam pattern, time delay, and noise is developed. This system will simulate a sonar signature for an arbitrary distribution of fish by making several simplifying assumptions. This thesis compares the simulated system sonar signature with assumed fish distribution to predict the accuracy of the sonar fish counting system.
    • Thermal analysis and cold start performance of automotive emission systems

      Kumar, Sumit (2002-08)
      Automotive exhaust emission regulations are becoming stricter due to increasing awareness of the hazardous effects of exhaust emissions. The main challenge to comply with the EPA regulations is to reduce the emissions during cold start, because catalytic converters are ineffective until they reach a 'light-off' temperature - the temperature at which the converter starts reducing 50 % of emissions. A thermal model of a catalytic converter is presented which reduces the light-off time and significantly reduces the concentration of exhaust gas emissions. This thesis describes a numerical model of the catalytic converter, which is used to predict catalytic converter performance during cold-starts. Simulations were carried out using a finite element software - Abaqus, to study the catalytic converter performance at various temperatures. After analyzing thermal models for both - uniform heat distribution and cost effectiveness, a heat source of 90 W was chosen for a three-heater configuration (30 W each) to pre-heat the converter. A reduction in the concentration of emissions by a factor of 4 to 6 were recorded as a result of vehicle simulation with this thermally designed catalytic converter. ADVISOR (Advanced Vehicle Simulator), a vehicle simulator, was used to calculate 'engine-out emissions.'
    • Design and implementation of an embedded controller for a vehicle navigation unit

      Satavalekar, Bipin P. (2002-08)
      This thesis describes the design and implementation of an embedded controller that is used for the Vehicle Navigation Unit (VNU) prototypes that are being developed at the University of Alaska Fairbanks (UAF). The goal of the VNU project is to develop a system that will measure relative position and provide wireless communication between four identical vehicles without the use of GPS signals. Each VNU consists of an antenna and phase detector array, embedded controller, radio modem magnetometer, and a diagnostic computer. The main focus of this thesis is the design and implementation of the embedded controller hardware and software that integrates all the VNU components into an operational system. The embedded controller utilizes the Motorola MC68HC711E9 microcontroller and the Zilog Z85230 Serial Communication Controller that receives and transmits the data serially. The relative distance and bearing between VNUs is estimated by measuring the angle of arrival and received signal strength of the radio frequency packets transmitted by each VNU. The magnetometer is used to monitor the horizontal orientation of the VNU and to serve as a fixed referencefor comparing the relative bearing between vehicles. These raw measurements are archived into a diagnostic computer, which estimates the relative position between the VNUs and provides a graphical representation. These VNU prototypes are designed for ideal environments and are intended to provide a test bed for evaluating signal processing and hardware strategies for mitigating multipath effects. The complete VNU design is presented, started with a functional block diagram of the hardware and software, and concluding with operational tests that demonstrate the performance of the fully integrated prototype.
    • Sounding rocket payload electrical systems designs system: a systems approach applied to the DIONISYS payload

      Burket, V. Edward (2002-08)
      Documentation of a comprehensive sounding rocket payload electrical system design methodology is needed by the Alaska Student Rocket Program (ASRP) in order to allow future student designers to build upon the knowledge and experience developed on previous sounding rocket missions, rather than rediscover valuable techniques that were never documented. A systems approach to sounding rocket payload design is presented and supported by a detailed presentation and analysis of the Hawkins/30.047UO 'DIONISYS' (D-region IONIzation measurement SYStem) payload design that was used to measure the D-Region ionization density at high latitudes. Fabrication techniques and test methods that ensure the payload will survive the launch environment are also presented, as well as a post-flight analysis of the successfully launched and recovered payload.
    • Modeling and optimization of hybrid electric power systems for remote locations in extreme northern climates

      Agrawal, Ashish N. (2003-08)
      This thesis presents a long-term performance model of a hybrid electrical power system for remote locations in various parts of the world. The model incorporates the performance of different components of the hybrid power system in extreme northern climates. The hybrid model presented uses the graphical user interface available in MATLAB Simulink. Two variations of the hybrid model were developed. One model consists of a photo voltaic (PV) array with a diesel-battery system and the other model consists of a wind turbine with a diesel-battery system. The main performance criterion by which the system was evaluated is the percentage of fuel savings relative to the diesel only case. The results show the significant savings in fuel consumption due to the penetration of the battery bank, the photovoltaic module and the wind turbines in the diesel-only system, while increasing the overall efficiency of the system. This simulation tool will help designers to determine the best hybrid mix of diesel generation, battery storage, photovoltaics, and wind generation for optimal performance of the system in remote villages like those found in Alaska and other developing countries. Examples are presented based on actual systems in the remote Alaskan communities of Lime Village (PV with a diesel-battery) and Wales Village (wind with a diesel-battery).