Matching Items (40)

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Performance Modeling of a Concentrating Photovoltaic Two-Axis Tracker

Description

The purpose of this research is to study the effect of angle of acceptance and mechanical control system noise on the power available to a two-axis solar concentrating photovoltaic (CPV)

The purpose of this research is to study the effect of angle of acceptance and mechanical control system noise on the power available to a two-axis solar concentrating photovoltaic (CPV) system. The efficiency of a solar CPV system is greatly dependent on the accuracy of the tracking system because a strong focal point is needed to concentrate incident solar irradiation on the small, high efficiency cells. The objective of this study was to evaluate and quantify tracking accuracy for a performance model which would apply to similar two-axis systems. An analysis comparing CPV to traditional solar photovoltaics from an economic standpoint was conducted as well to evaluate the viability of emerging CPV technology. The research was performed using two calibrated solar radiation sensors mounted on the plane of the tracking system, normal to the sun. One sensor is held at a constant, normal angle (0 degrees) and the other is varied by a known interior angle in the range of 0 degrees to 10 degrees. This was to study the magnitude of the decrease in in irradiance as the angle deviation increases. The results show that, as the interior angle increases, the solar irradiance and thus available power available on the focal point will decrease roughly at a parabolic rate, with a sharp cutoff point at angles greater than 5 degrees. These findings have a significant impact on CPV system tracking mechanisms, which require high precision tracking in order to perform as intended.

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  • 2017-05

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The Development of a Power System for the Phoenix CubeSat

Description

The Phoenix CubeSat is a 3U Earth imaging CubeSat which will take infrared (IR) photos of cities in the United Stated to study the Urban Heat Island Effect, (UHI) from

The Phoenix CubeSat is a 3U Earth imaging CubeSat which will take infrared (IR) photos of cities in the United Stated to study the Urban Heat Island Effect, (UHI) from low earth orbit (LEO). It has many different components that need to be powered during the life of its mission. The only power source during the mission will be its solar panels. It is difficult to calculate power generation from solar panels by hand because of the different orientations the satellite will be positioned in during orbit; therefore, simulation will be used to produce power generation data. Knowing how much power is generated is integral to balancing the power budget, confirming whether there is enough power for all the components, and knowing whether there will be enough power in the batteries during eclipse. This data will be used to create an optimal design for the Phoenix CubeSat to accomplish its mission.

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Date Created
  • 2017-05

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Planing and The Effect of Bicycle Frame Stiffness on Rider Performance

Description

It is a common assumption in the bicycle industry that stiffer frames generally perform better than flexible frames, because they transfer power more efficiently and absorb less energy from the

It is a common assumption in the bicycle industry that stiffer frames generally perform better than flexible frames, because they transfer power more efficiently and absorb less energy from the rider's pedal stroke in the form of spring potential energy. However, in the last few years, Jan Heine of Bicycle Quarterly has developed an alternative theory, which he calls "planing", whereby a flexible frame can improve rider performance by not resisting the leg muscles as much, preventing premature muscle fatigue and allowing the rider to actually produce more consistent power, an effect which overwhelms any difference in power transfer between the different stiffness levels of frames. I performed several tests in which I measured the power input to the bicycle through the crankset and power output through a power-measuring trainer in the place of the rear hub. Heart rate data was collected along with most of these tests. Four bicycles were used with three distinct levels of stiffness. After performing several ANOVA tests to determine the effect of stiffness on the parameters of average power output during a sprint, maximum power output during a sprint, maximum heart rate during a sprint, difference between power-in and power-out during both sprints and longer efforts, and power quotient during a sprint, I found no effects of frame stiffness on any of these factors except power quotient. The finding for power quotient suggests a positive relationship between quotient and stiffness, which directly refutes the Planing Theory for the test riders and levels of stiffness represented in this test. Also, no statistically significant effect of stiffness on the difference between power-in and power-out was found, refuting the Power Transfer Theory for the riders and levels of stiffness represented in this test.

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Date Created
  • 2016-12

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Active Ripple Cancellation in Hysteretic Controlled Buck Converters

Description

Buck converters are a class of switched-mode power converters often used to step down DC input voltages to a lower DC output voltage. These converters naturally produce a current and

Buck converters are a class of switched-mode power converters often used to step down DC input voltages to a lower DC output voltage. These converters naturally produce a current and voltage ripple at their output due to their switching action. Traditional methods of reducing this ripple have involved adding large discrete inductors and capacitors to filter the ripple, but large discrete components cannot be integrated onto chips. As an alternative to using passive filtering components, this project investigates the use of active ripple cancellation to reduce the peak output ripple. Hysteretic controlled buck converters were chosen for their simplicity of design and fast transient response. The proposed cancellation circuits sense the output ripple of the buck converter and inject an equal ripple exactly out of phase with the sensed ripple. Both current-mode and voltage-mode feedback loops are simulated, and the effectiveness of each cancellation circuit is examined. Results show that integrated active ripple cancellation circuits offer a promising substitute for large discrete filters.

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Date Created
  • 2017-12

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A Comparison of the Effects of Two Warm- Up Protocols on Strength and Power in College- Aged Females

Description

The following study compared the effects of acute static stretching (SS) and whole body vibration (WBV) protocols on strength and power in college-aged recreationally active females. Ten active, Arizona State

The following study compared the effects of acute static stretching (SS) and whole body vibration (WBV) protocols on strength and power in college-aged recreationally active females. Ten active, Arizona State University females participated in the study after providing informed consent and filling out a survey to determine their health status and physical activity level. Participants took part in the study over two days, each day starting with a standardized cycling protocol, followed by random assignment to either a static stretching or whole body vibration warm-up condition. Whichever protocol they did not complete during the first session, they completed during the second session. After the warm-up protocol, vertical hang time and vertical jump were used to test leg power, and 1- RM bench press, and 1- RM leg press were used to evaluate the participants’ upper and lower body strength, respectively. Multiple t-tests were conducted for each sports performance test conducted: vertical hang time, vertical jump, bench press, and leg press. Strength and power, as assessed in this sample, were not significantly different based on warm-up protocol. T-tests comparing the effects of two warm-up techniques revealed that there were no significant differences in the leg power scores for vertical hang time (p ≤0.86) (effect size = 0), or vertical jump height (p =1) (effect size = 0). Similarly, there were no significant differences in bench press (p ≤0.08) (effect size = 0.38), and leg press (p ≤0.29) (effect size = 0.31), although effect sizes were moderate. Because of the medium effect sizes for leg press (0.31) and bench press (0.38), it is possible that WBV can facilitate greater strength gains in female college students, but more subjects are needed to further evaluate this finding. Given that leg power was not different based on warm-up technique, it is possible that static stretching for less than 30 seconds did not impede power in these active females. Clearly, more research needs to be performed on the effectiveness of the vibration platform comparing additional bouts of duration and frequency in active and athletic college-aged females.

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Date Created
  • 2017-12

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Nested Capacitor Power Generation Through Aligning Fields

Description

Two nested capacitors can produce work if the electric fields are not aligned, and the purpose of this research was to explore the possibility of using that generation instead of

Two nested capacitors can produce work if the electric fields are not aligned, and the purpose of this research was to explore the possibility of using that generation instead of DC motors. The work the capacitors produce is determined by the strength of the fields and materials that is composed of. The power density of the object is then determined by the volume. As the electric field increases in strength, the power increases, so to create a very strong internal field. The nested capacitors use a dielectric to prevent breakdown from the strength of the field. Additionally, as the nested capacitors decrease in size, their power density increases rapidly \u2014 becoming close to a dc motor's power density around the 500mm^2 size. When the result was simulated, it was discovered that the electric field was not contained to the dielectric and would result in sparking. Several other concerns would need to be addressed for this to become a viable solution.

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Date Created
  • 2018-05

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Understanding Why Utilities Are Moving Towards Residential Demand Pricing and Analyzing Effectiveness in Methods of Communication

Description

An increasing amount of utilities are moving towards residential demand pricing, causing much controversy and miscommunication between the provider and the consumer as to what demand pricing is, and what

An increasing amount of utilities are moving towards residential demand pricing, causing much controversy and miscommunication between the provider and the consumer as to what demand pricing is, and what it entails for the consumer. This paper will analyze the effectiveness of utility-consumer communication methods and how Arizona utility companies (Salt River Project and Arizona Public Service) have migrated the obstacles of TOU (Time of Use) pricing changes to Arizona utility residents, especially to solar customers. SRP (Salt River Project) and APS (Arizona Public Service) have both implemented pilot programs including the E-27 for SRP and the Saver Choice Plus plan for APS . Both programs, along with international programs, have seen varying levels of success for their business and for consumers to grasp peak-demand pricing and usage. Overall, APS customers have seen an average increase of 4.5% on their electricity bills while SRP customers have experienced, on average, a $19.00 increase. Despite these bill increases, both utilities have seen a decrease in customer electricity demand in response to higher energy costs during peak times.

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Date Created
  • 2018-05

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Design of Advanced DC-AC Converter for Underprivileged Communities

Description

Growing up in Ghana West Africa, I realized there were a few major obstacles hindering the education of the youth. One of them was the consistent supply of all year-round

Growing up in Ghana West Africa, I realized there were a few major obstacles hindering the education of the youth. One of them was the consistent supply of all year-round power. Therefore, pursuing a career in power electronics, I decided to research and implement a budget-friendly DC-AC converter that can take power from a DC source such as a solar panel to make AC power, suitable for grid-implementation. This project was undertaken with two other colleagues (Ian Vogt and Brett Fennelly), as our Senior Design Capstone project. My colleagues primarily researched into the "advanced" part of the converter such as Volt-VAR, Maximum Power Point Tracking (MPPT), and variable power factor, making the Capstone project be dubbed as "Smart Inverter". In this paper, I elaborate on the entire process of my research and simulation, through the design and layout of the PCB board to milling, soldering and testing. That was my contribution to the capstone project. After testing the board, it was concluded that although the inverter was intended to be the very inexpensive, some electrical and design principles could not be compromised. The converter did successfully invert DC power to AC, but it was only at low voltage levels; it could not withstand the higher voltages. This roadblock stymied the testing of advanced functionalities, paving way for an avenue of further research and implementation.

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Date Created
  • 2018-05

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Dangers of Information Control and Misinformation in the Modern Era

Description

The basis of social power which has expanded in the most dangerous way over the last few decades has been that of information control, and how that control is used.

The basis of social power which has expanded in the most dangerous way over the last few decades has been that of information control, and how that control is used. Misinformation and the intentional spread of misinformation referred to as disinformation, has become commonplace among various bodies of power to either expand their own influence or diminish opposing influence. The methods of disinformation utilized in the various spheres of politics, the commercial marketplace, and the media today are explored in depth to better contextualize and describe the problems that disinformation and its use pose in the world today.

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Date Created
  • 2021-05

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Cash Cab and Women's Oppression: A Study in Linguistics

Description

A study on the power inequity between men and women in inter-gender conversations, how it manifests linguistically, and the social ramifications thereafter. Conversations from the game show Cash Cab are used to this point.

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Date Created
  • 2021-05