Open Access. Powered by Scholars. Published by Universities.®

Physics Commons™

Open Access. Powered by Scholars. Published by Universities.®

Electrical and Computer Engineering

Linfield University

Articles 1 - 12 of 12

Full-Text Articles in Physics

Design Of Smart Trashcan, Haoran Song Apr 2021

Design Of Smart Trashcan, Haoran Song

Senior Theses

A smart trashcan has been designed which can bring convenience to people for throwing their garbage away during the COVID-19 pandemic. A prototype is made from cardboard to demonstrate its function. This trashcan can sense people who are coming and leaving, and it can open and close automatically. The trashcan is powered by solar energy. A solar panel is mounted on top of the trashcan supporter. This design is specifically for use in China.

Go to article

Exploring The Electrical Properties Of Twisted Bilayer Graphene, William Shannon May 2019

Exploring The Electrical Properties Of Twisted Bilayer Graphene, William Shannon

Senior Theses

Two-dimensional materials exhibit properties unlike anything else seen in conventional substances. Electrons in these materials are confined to move only in the plane. In order to explore the effects of these materials, we have built apparatus and refined procedures with which to create two-dimensional structures. Two-dimensional devices have been made using exfoliated graphene and placed on gold contacts. Their topography has been observed using Atomic Force Microscopy (AFM) confirming samples with monolayer, bilayer, and twisted bilayer structure. Relative work functions of each have been measured using Kelvin Probe Force Microscopy (KPFM) showing that twisted bilayer graphene has a surface potential …

Go to article

Manufacturing And Testing The Permanent Magnet Linear Motor, Renjie Kang May 2019

Manufacturing And Testing The Permanent Magnet Linear Motor, Renjie Kang

Senior Theses

Controlled mechanical motion is vital in many useful applications in technology. Among them, linear motors have advantages over traditional rotating motors. In this work, we built a permanent magnet linear motor to test and measure its energy efficiency. A maximum 29% total energy efficiency, and 67% energy transfer rate, were detected. In addition, a C-shape support structure was added to the moving part in order to increase the moving accuracy. The tests show that, with the support structure, the fluctuation in the vertical direction decreases significantly, but the friction of the system slightly increases.

Go to article

A Human Powered Micro-Generator For Charging Electronic Devices, John Adam May 2018

A Human Powered Micro-Generator For Charging Electronic Devices, John Adam

Senior Theses

A hand-pulled generator has been designed and tested. A preliminary result has been obtained and discussed. This device was created to provide outlet-free charging. Electronic devices are useful when going out into the wilderness. A portable power supply is necessary to keep an electronic device alive. This project created a device that converts human energy into electricity to charge electronic devices. This thesis overviews the device’s design, build, and tests. Two different tests were run to determine that the device is capable of charging the storage battery. The device presented can provide 14 minutes of charging time with one hour …

Go to article

Increasing The Longevity Of Tungsten Filaments In A Zone Refiner, Byron D. Greenlee May 2018

Increasing The Longevity Of Tungsten Filaments In A Zone Refiner, Byron D. Greenlee

Senior Theses

Zone refining is used for its ability to purify material and grow single crystals. To produce these single crystals, a suspended molten zone, generated by electron bombardment, passes along the polycrystalline stock. During a zone refining run, the filaments that produce the electron bombardment can fail. In this project, the longevity of tungsten filaments in a zone refiner was investigated. A new bombardment geometry was constructed to attempt to increase the longevity of the filaments. The new geometry had a shield machined into it to prevent line-of-sight impurities originating in the molten zone from striking the filaments. It was found …

Go to article

Thermoelectrics And Thermoelectric Devices, Benjamin T. Erck May 2018

Thermoelectrics And Thermoelectric Devices, Benjamin T. Erck

Senior Theses

The field of thermoelectrics has many applications, and more are found in everyday systems. From its current studies, it is apparent that improving the figure of merit zT (which defines a good thermoelectric material) is important in the effectiveness of power generation. Another important part of thermoelectrics is the duality of these devices. They can both move heat and generate power, depending on their role in the system. In this thesis research, a process was made to test these thermoelectric relationships for a few Peltier devices in order to understand their efficiencies and what systems they can be applied to.

Go to article

Measuring The Double Layer Capacitance Of Electrolytes With Varied Concentrations, Geoffrey Rath May 2018

Measuring The Double Layer Capacitance Of Electrolytes With Varied Concentrations, Geoffrey Rath

Senior Theses

When electric potentials are applied from an electrolytic fluid to a metal, a double layer capacitor, Cdl, develops at the interface. The layer directly at the interface is called the Stern layer and has a thickness equal to roughly the size of the ions in the fluid. The next layer, the diffuse layer, arises from the gathering of like charges in the Stern layer. This layer is the distance needed for ionic charges to return to equilibrium. This distance, called the Debye length, λ, depends on the square root of the electrolyte concentration. To study the properties of …

Go to article

Measuring The Double Layer Capacitance Of Electrolyte Solutions Using A Graphene Field Effect Transistor, Agatha Ulibarri May 2018

Measuring The Double Layer Capacitance Of Electrolyte Solutions Using A Graphene Field Effect Transistor, Agatha Ulibarri

Senior Theses

When operating graphene field effect transistors (GFETs) in fluid, a double layer capacitance (Cdl) is formed at the surface. In the literature, the Cdl is estimated using values obtained using metal electrode experiments. Due to the distinctive electronic and surface properties of graphene, there is reason to believe these estimates are inadequate. This work seeks to directly characterize the double layer capacitance of a GFET. A unique method for determining the Cdl has been implemented, and data has been obtained for three electrolytes and one ionic fluid. The results yield dramatically lower Cdl values than …

Go to article

Operating Temperature Of A Solar Thermal Stirling Engine, Spencer Beck May 2017

Operating Temperature Of A Solar Thermal Stirling Engine, Spencer Beck

Senior Theses

This paper explores the relationship between the operating temperature and electricity production of a simple heat engine. A Stirling engine was designed and constructed which runs on solar thermal energy collected by a Fresnel lens. The surface area of the solar collector was varied. This manipulated the operating temperature of the Stirling engine in order to measure power output. The mechanical energy from the engine was converted to electricity using a DC motor running in reverse, acting like a generator, in conjunction with an Arduino for data collection. Although adjustments must be made in order to improve the efficiency of …

Go to article

Are Solar Panels A Viable Power Source For A Green Energy Vehicle?, Mason C. Adams May 2017

Are Solar Panels A Viable Power Source For A Green Energy Vehicle?, Mason C. Adams

Senior Theses

A solar cell powered go-kart has been built and tested. The result shows using solar energy alone cannot meet the requirement of running a regular passenger car. This is due to the limited surface area of the passenger car. This thesis also discusses the operating principles of solar panels, the physics of P type and N type semiconductors, and the formation of the PN junction, as well as the solar current. Modifications of an existing go-kart are described in detail in this thesis. Suggestions for making green vehicles are discussed as well.

Go to article

Reflective Efficiencies Of Materials For Applications Of Bifacial Solar Cells, Michael Metter May 2016

Reflective Efficiencies Of Materials For Applications Of Bifacial Solar Cells, Michael Metter

Senior Theses

The bifacial solar cell is superior to its monofacial predecessor due to its ability to convert both incident light on top and reflected light from below into energy. The scattering of the reflected light is affected by the property of the material on which it is interacting. To date, little work has been contributed to studying the properties of these materials to determine optimal quantities for bifacial solar cells. In the first experiment, reflective efficiencies compared to the angle of reflection were explored for different grit of sandpaper in order to develop an understanding of how surface texture impacts reflectivity. …

Go to article

Effect Of Ga Content On Defect States In Cuin1-XGaXSe2 Photovoltaic Devices, Jennifer T. Heath, J. David Cohen, William N. Shafarman, Dongxiang Liao, Angus Rockett Jan 2002

Effect Of Ga Content On Defect States In Cuin1-XGaXSe2 Photovoltaic Devices, Jennifer T. Heath, J. David Cohen, William N. Shafarman, Dongxiang Liao, Angus Rockett

Faculty Publications

Defects in the band gap of CuIn1-xGaxSe2 have been characterized using transient photocapacitance spectroscopy. The measured spectra clearly show response from a band of defects centered around 0.8 eV from the valence band edge as well as an exponential distribution of band tail states. Despite Ga contents ranging from Ga/(In+Ga)=0.0 to 0.8, the defect bandwidth and its position relative to the valence band remain constant. This defect band may act as an important recombination center, contributing to the decrease in device efficiency with increasing Ga content.

Go to article