Electrical and Electronics Commons^™

การปลูกและวิเคราะห์ลักษณะสมบัติของฟิล์มแกลเลียมอาร์เซไนด์ฟอสไฟด์บิสไมด์บนแกลเลียมอาร์เซไนด์และฟิล์มอินเดียมฟอสไฟด์บิสไมด์บนแกลเลียมแอนติโมไนด์, สหรัฐ ชมเดช

Chulalongkorn University Theses and Dissertations (Chula ETD)

วิทยานิพนธ์ฉบับนี้นำเสนอการปลูกชั้นฟิล์ม GaAsPBi บนแผ่นฐาน GaAs เพื่อลดความบกพร่องของโครงผลึกในชั้นฟิล์ม และชั้นฟิล์ม InPBi บนแผ่นฐาน GaSb เพื่อให้เกิดการดึง Bi เข้ามาผสมในชั้นฟิล์มมากขึ้น ชิ้นงานถูกปลูกโดยเทคนิคเอพิแทกซีลำโมเลกุล (MBE) นอกจากนี้ชิ้นงาน GaAsPBi ถูกนำไปอบที่อุณหภูมิสูง เพื่อศึกษาผลกระทบของอุณหภูมิที่มีต่อคุณสมบัติของวัสดุ ชิ้นงาน GaAsPBi ถูกศึกษาสัณฐานวิทยาด้วยกล้องจุลทรรศน์แรงอะตอม (AFM) จุลทรรศน์แบบใช้แสง (OM) และ กล้องจุลทรรศน์อิเล็กตรอนแบบส่องกราด (SEM) ถูกศึกษาโครงสร้างผลึกด้วยเทคนิค XRD ถูกศึกษา oxidation state และองค์ประกอบของธาตุในชั้นฟิล์มด้วยเทคนิคการดูดกลืนรังสีเอกซ์ (XAS) และถูกศึกษาคุณสมบัติเชิงแสงด้วยเทคนิค PL ชิ้นงาน InPBi ถูกศึกษาสัณฐานวิทยาด้วยกล้องจุลทรรศน์แรงอะตอม (AFM) ถูกศึกษาโครงสร้างผลึกด้วยเทคนิค XRD และถูกศึกษาคุณสมบัติเชิงแสงด้วยเทคนิค PL. ผลการวิเคราะห์ชิ้นงาน GaAsPBi แสดงว่าชิ้นงานที่ได้รับการปรับปรุงเงื่อนไขการปลูก ไม่มีความบกพร่องของโครงผลึกบนผิวหน้า เนื่องจากชั้นฟิล์มมีค่าคงตัวแลตทิซใกล้เคียงกับแผ่นฐาน มีปริมาณของ Bi ในชั้นฟิล์มเพิ่มขึ้น และมีปรับปรุงผลตอบสนองเชิงแสงให้ดีขึ้น การศึกษาผลของการอบชิ้นงานพบว่า การอบที่ 650°C เกิดการทำลายผิวหน้าของชิ้นงาน ทำให้คุณภาพผลึกแย่ลง การอบช่วยเพิ่มประสิทธิภาพการเปล่งแสงได้เล็กน้อยในกรณีการอบที่อุณหภูมิ 450°C และ 550°C แต่การอบที่ 650°C ทำให้ประสิทธิภาพการเปล่งแสงลดลงไปอย่างมาก และการอบไม่ส่งผลต่อองค์ประกอบในชั้นฟิล์ม ชั้นฟิล์ม InPBi มีโครงผลึกที่มีการคลายความเครียด ทำให้ผิวหน้ามีความขรุขระ ความขรุขระของผิวหน้าและปริมาณของ Bi ในชั้นฟิล์ม ถูกพบว่าแปรผันกับอุณหภูมิปลูกและปริมาณของ Bi ในลำโมเลกุล ผลตอบสนองเชิงแสงของชิ้นงานแสดงยอดการเปล่งแสงหลายยอด ชิ้นงานที่มีปริมาณ Bi มากที่สุดถูกปลูกที่อุณหภูมิ 300°C โดยมีปริมาณ Bi ในลำโมเลกุลเป็น 2×10-8 Torr ซึ่งทำให้มี Bi ในชั้นฟิล์มเป็น 2.45% เมื่อเปรียบเทียบกับชั้นฟิล์มที่ปลูกด้วยเงื่อนไขเดียวกันบนแผ่นฐาน InP แล้ว พบว่ามีปริมาณ Bi ที่มากกว่าเล็กน้อยในชั้นฟิล์มที่ปลูกบน GaSb

Solid Loading Effects On The Assembly Of Alumina Particles In Aqueous Suspensions Due To The Dielectrophoretic Forces, Sivakumar Chithamallu, Rohan Kiran Parai, Dipankar Ghosh

Mechanical & Aerospace Engineering Faculty Publications

Current work in situ investigated the mechanisms of the interparticle interactions that evolve in dilute aqueous alumina suspensions subjected to alternating current (AC) electric field and the effects of solid loading of suspensions. The interactions were investigated for alumina suspension compositions in the 0.005‒0.04 vol.% solid loading range. Field‐induced interactions evolved via particle motion and dynamic assembly, chain formation parallel to the direction of the applied field and chain growth, chain cross‐linking, and chain thickening. The evolution time of each of those events was rapidly accelerated with solid loading. While chain cross‐linking was negligible in low solid loading suspensions, a …

3d Printing Metal Horn Antennas Using Periodic And Aperiodic Perforated Designs For Directed Energy Applications, Alexis Valencia

Open Access Theses & Dissertations

In the past decade, Additive Manufacturing (AM) has proven to be groundbreaking yet reliable technology. Not only has it revolutionized the way we approach problems in research, design, and production but it has enabled burgeoning discoveries and methods due to the technologyâ??s efficiency, speed, and low manufacturing cost. One area that benefits greatly from this includes radio frequency (RF) devices like horn antennas. At the moment, most horn antennas produced by conventional manufacturing are expensive, heavy, and limited in customization, yet they are necessary for various systems like satellite communication, radar, radio astronomy, and more. 3D printing technology would alleviate …

Correlation Of Internal Pressure To The Fundamental Aging Mechanism Of Li-Ion Batteries, Kayla Garcia

Electrical Engineering Theses - Archive

As technology continues to evolve, the demand for more reliable and longer-lasting batteries is growing rapidly in the electronics industry. Batteries are vital for powering a wide range of technologies, from smartphones and consumer electronics to automotive systems and high-end tools used across multiple sectors. Lithium-ion batteries (LIBs) have helped bridge the power and energy gap that these different technologies require while achieving sufficient efficiency and reliability to make carrying them around feasible and long lasting. To further enhance the performance and longevity of a these devices, a deeper understanding of the degradation mechanisms occurring inside LIBs is crucial. The …

Safety Monitoring & Intelligent Power Distribution Systems For Compact Agricultural Equipment, Mason O. Bradley

Theses and Dissertations--Biosystems and Agricultural Engineering

The agricultural industry continues to be one of the most dangerous career fields in the United States of America with compact agricultural equipment being a common source for casualties in the industry. The primary focus of this work is to develop new technology that improves operational safety of compact agricultural equipment through the use of low-cost embedded electronics. This work presents the design of three systems in alignment with this goal.

The first system aims to integrate electrical intelligence and passive safety monitoring into the power distribution system of a small piece of agricultural equipment. The system known as the …

Mxenes In Biosensing: Enhancing Sensitivity And Flexibility - A Review Of Properties, Applications, And Future Directions, Ali Mohammad Amani, Lobat Tayebi, Ehsan Vafa, Alireza Jahanbin, Milad Abbasi, Ahmed Vaez, Hesam Kamyab, Lalitha Gnanasekaran, Shreeshivadasan Chelliapan

Electrical & Computer Engineering Faculty Publications

MXenes are a novel type of nanostructured material that has received a lot of attention for their potential applications in bioanalysis owing to their unique features. These materials, made from transition metal nitrides, carbides, or carbonitrides, have a number of advantages, including high hydrophilicity, a large surface area, strong metallic conductivity, superior ion transport capabilities, biocompatibility, and low diffusion barriers. Their surfaces are easily manipulated, making them more adaptable for a variety of applications, including biosensing. The outstanding properties of MXenes have attracted researchers of different fields, including renewable energy, fuel cells, supercapacitors, electronics, and catalysis. In the context of …

Development Of 2d Microfluidics Surface With Low-Frequency Electric Fields For Cell Separation Applications, Madushan Wickramasinghe, Dharmakeerthi Nawarathna

Electrical & Computer Engineering Faculty Publications

Cell separation techniques are widely used in many biomedical and clinical applications for the development of screening, diagnosis and therapeutic tests. Current 3D microfluidics-based cell separation methods have limited applications in part due to low throughput and technical complexity. To address these critical needs, we have developed a 2D microfluidics surface which is the miniaturized version of a 3D microfluids cell separation device. Using low-frequency electric fields (1–10 Vpp and 1 kHz–20 MHz), we have first studied dielectrophoresis, AC electro-osmosis and capillary flow within a sessile drop, and finally utilized the results to develop the 2D cell separation surface. Our …

Flux-Weakening Control Methods For Permanent Magnet Synchronous Machines In Electric Vehicles At High Speed, Samer Alwaqfi, Mohamad Alzayed, Hicham Chaoui

Electrical & Computer Engineering Faculty Publications

Permanent magnet synchronous motors (PMSMs) are widely favored by manufacturers for use in electric vehicles (EVs) because of their many benefits, which include high power density at high speeds, ruggedness, potential for high efficiency, and reduced control complexity. However, since the Back Electromotive Force (EMF) increases proportionally with the motor’s rotational speed, it must be carefully controlled at high speeds. Flux-weakening (FW) control is required to avoid excessive electromagnetic flux beyond the power source and inverter’s voltage restrictions. This paper aims to compare various FW control strategies and analyze their effectiveness in maximizing the speed of PMSMs in EV applications …

The Effect Of Electrode Geometry On Excited Species Production In Atmospheric Pressure Air-Hydrogen Streamer Discharge, Shirshak Kumar Dhali, Stuart Reyes

Electrical & Computer Engineering Faculty Publications

When a gas is overvolted at or near atmospheric pressure, it results in a streamer discharge formation. Electrode geometries exert significant impact on the electrical breakdown of gases by altering the spatial profile of the electric field. In many applications the efficient generation of radicals is critical and is determined by the characteristics of the streamer discharge. We examine the effect of electrode geometry on the streamer characteristics and the production of radicals. This is performed for three different electrode geometries: plane–plane, pin–plane, and pin–pin. A two-dimensional rotationally symmetric fluid model is used for the streamer discharge simulation in the …

The Effect Of Electrode Geometry On Excited Species Production In Atmospheric Pressure Air–Hydrogen Streamer Discharge, Shirshak Kumar Dhali, Stuart Reyes

Electrical & Computer Engineering Faculty Publications

When a gas is overvolted at or near atmospheric pressure, it results in a streamer discharge formation. Electrode geometries exert significant impact on the electrical breakdown of gases by altering the spatial profile of the electric field. In many applications the efficient generation of radicals is critical and is determined by the characteristics of the streamer discharge. We examine the effect of electrode geometry on the streamer characteristics and the production of radicals. This is performed for three different electrode geometries: plane–plane, pin–plane, and pin–pin. A two-dimensional rotationally symmetric fluid model is used for the streamer discharge simulation in the …

Implementation Of Quantized Artificial Neural Networks With Spintronic Stochastic Computing, Saadi Sabyasachi Mr.

Theses and Dissertations

Artificial intelligence or machine learning is going through a rapid expansion. It also incurs significant costs for power and device footprints. Various approaches are being explored to design energy and hardware efficient machine learning models. Stochastic computing has been proposed for efficient machine learning implementation. It requires a source of random number generation which poses some practical challenges. So spintronic solutions such as magnetic tunnel junction has been used for random number generation. Again, spintronic random number generation to implement high precision circuit is prone to device-to-device variations. Hence we designed quantized artificial neural network with spintronic stochastic computing which …

Modeling And Analysis Of Amorphous Steel Transformer For Potential Loss Reduction In Power Systems., Daniel A. Muchow

Theses and Dissertations--Electrical and Computer Engineering

The energy consumed in power systems can be reduced directly by implementing new technologies and materials. The effort to reduce the carbon emissions expelled from the production of electrical energy has become a major focus. According to the U.S. energy Information Administration approximately 5% of all the electric generated and transmitted in the U.S. electrical grid is lost. The energy profile calculated from the usage of electrical power from all 50 states in 2021 is estimated to be 3.8 billion megawatts per hour, with a state average of just over 11 cents per MWh, producing just over 41.8 billion in …

A Multiscale Ai Framework For Forest And Agriculture Health Monitoring: Drone-Based Object Recognition And Segmentation For Automated Ecological Assessment, Sruthi Keerthi Valicharla

Graduate Theses, Dissertations, and Problem Reports (ETD)

Forest and agricultural ecosystems are increasingly at risk due to invasive species, pests, and diseases, necessitating scalable, automated, and intelligent monitoring solutions. Traditional field based forest and agriculture health assessments are limited by cost, time, and spatial coverage. This dissertation presents a multiscale deep learning framework that automates forest and agriculture health monitoring using drone imagery and computer vision techniques. The system operates across three spatial levels: forest level, tree level, and leaf level, combining object detection, segmentation, and classification models to support large scale ecological assessment.

At the forest level, high-altitude drone imagery is processed using object detection and …

Rheology Of Alumina Suspensions Subjected To Alternating Current Electric Fields For Freeze-Casting, Sivakumar Chithamallu, Ruksana Baby, Jacob L. Jones, Dipankar Ghosh

Mechanical & Aerospace Engineering Faculty Publications

Alternating current (AC) electric field can extrinsically tune freeze‐cast microstructure, originating from field‐induced increase in viscosity of ceramic suspensions. However, the changes that occur in a ceramic suspension and rheological behavior, ultimately affecting freeze‐cast microstructure, are not well understood. Moreover, the effects of AC electrokinetic forces and temperature on viscosity need to be decoupled. The viscosity and temperature of ceramic suspensions subjected to AC field and direct heating were measured, revealing that the increase in viscosity is due to AC dielectrophoretic forces rather than field‐induced heating of suspension. The shear thinning behavior of suspensions characterized using a power‐law model reveals …

A Novel Intelligent Thermal Feedback Framework For Electric Motor Protection In Embedded Robotic Systems, Mohamed Shili, Salah Hammedi, Hicham Chaoui, Khaled Nouri

Electrical & Computer Engineering Faculty Publications

As robotic systems advance in autonomy and sophistication while being used in uncertain environments, the challenge of building reliable and robust electric motors that are embedded into robotic systems has never been a more important engineering problem. Thermal distress caused by extended operation or excessive loading can negatively affect a motor’s performance and efficiency and lead to catastrophic hardware failure. This paper proposes a novel intelligent control framework that includes real-time thermal feedback for hybrid electric motors that are embedded into robotic systems. The framework relies on adaptive control techniques and lightweight machine learning techniques to estimate internal motor temperatures …

Differential Equations' Coverage In Circuits And Heat Transfer Courses In An Engineering Technology Curricula, Otilia Popescu, Orlando Ayala

Engineering Technology Faculty Publications

Differential equations are at the core of any undergraduate engineering as well as of science programs. While a course in differential equations is required by any engineering degree, it is not a requirement for engineering technology programs, which usually require mathematics up to calculus I. This paper discusses the undergraduate engineering technology curricula, focusing on how differential equations are taught to engineering technology students and how they are covered in the programs. In particular, the paper will discuss the treatment of differential equations in electrical circuits and heat transfer courses.

Identification Of Π-Stacking Motifs In Naphthalene Diimides Via Solid-State Nmr, Jennifer E. Mejia, Hannah E. Butler-Au, Nalaya E. Thompson, Karcher D. Goodman, Elizabeth R. Zengel, Robert D. Pike, Jingdong Mao, Craig A. Bayse

Chemistry & Biochemistry Faculty Publications

Organic electronics, featuring π-conjugated small molecules and polymers, have gained significant attention for their potential in flexible, lightweight devices. However, characterization of the ordered, π-stacking domains within these materials using microscopy or X-ray diffraction (XRD) is challenging with complex systems or when crystallography is impractical. This study applied 1D ¹³C multiple cross-polarization magic angle spinning (multiCP/MAS) and 2D ¹H-¹³C heteronuclear correlation (HetCor) solid-state nuclear magnetic resonance (ssNMR) to systematically characterize π-stacking motifs in a series of N,N'-dialkyl naphthalene diimides (NDIs). These techniques were shown to distinguish between the electronic environments attributed to different π-stacking motifs adopted in these NDIs, such …

Antennas For Emerging Satellite Services, Jakub Przepiorowski

Doctoral

The NewSpace era has revolutionized access to space, driving advancements in satellite communication (SATCOM) systems and creating demand for low-cost, compact, and high-performance user terminals. This thesis addresses these needs by developing innovative antenna solutions tailored for user terminals designed for emerging satellite constellations and satellite Internet-of-Things (S-IoT) applications.

Fabrication Of Thylakoid Membrane-Based Photo-Bioelectrochemical Bioanode For Self-Powered Light-Driven Electronics, Amit Sarode, Gymama Slaughter

Center for Bioelectronics Publications

The transition toward sustainable and decentralized energy solutions necessitates the development of innovative bioelectronic systems capable of harvesting and converting renewable energy. Here, we present a novel photo-bioelectrochemical fuel cell architecture based on a biohybrid anode integrating laser-induced graphene (LIG), poly(3,4-ethylenedioxythiophene) (PEDOT), and isolated thylakoid membranes. LIG provided a porous, conductive scaffold, while PEDOT enhanced electrode compatibility, electrical conductivity, and operational stability. Compared to MXene-based systems that involve complex, multi-step synthesis, PEDOT offers a cost-effective and scalable alternative for bioelectrode fabrication. Thylakoid membranes were immobilized onto the PEDOT-modified LIG surface to enable light-driven electron generation. Electrochemical characterization revealed enhanced redox …

Dc To Dc Buck Converter, Matthew Bildstein

Williams Honors College, Honors Research Projects

This research project focuses on the design, implementation, and optimization of a high-efficiency DC-to-DC buck converter that steps down 12V to 5V for applications such as USB-powered devices, embedded systems, and automotive electronics. Building on my Associate’s degree project, where a 555 timer-based was replace with a LM2576 switching regulator IC.

The research involves circuit simulation in Multisim, PCB layout optimization in Ultiboard, and prototype testing to assess voltage stability, efficiency, and thermal performance. The project will incorporate best practices in power electronics design, including proper grounding techniques and thermal management strategies.

Expected outcomes …