Mechanical Engineering Commons^™

Zero-G Exercise Equipment, Charisse Biglete, Jake Brajevich, James Monroe, Ethan Siahpush

Mechanical Engineering

In a micro-gravitational environment, the body undergoes less loading than that found on Earth. This leads to muscular atrophy, Osteoporosis, decreases in protein synthesis, and various other undesirable outcomes. To prevent this, astronauts undergo a strict exercise regime to maintain their health. The current exercise equipment available for spacecraft is large, heavy, complicated to use, costly, and unsafe. There is a definite need for the re-engineering of the exercise equipment to be used by astronauts while in microgravity environments to rectify these issues.

Data-Driven Techno-Economic Analysis, Optimization, And Uncertainty Quantification Of Integrated Energy Systems In Deregulated Electricity Markets, Jacob A. Bryan

All Graduate Theses and Dissertations, Fall 2023 to Present

Electricity is a ubiquitous energy source in daily life, powering everything from stovetops and cellphones to vehicles and industrial processes. While wind and solar power have become increasingly common sources of electricity, the majority of electricity is still produced by burning fossil fuels, releasing greenhouse gases and propelling climate change. Wind and solar power cannot economically replace these fossil fuel energy sources on their own because they do not produce consistent power; the wind must be blowing, and the sun must be shining for them to make electricity. Nuclear power is a reliable source of energy that does not generate …

Prediction Of Dislocation Density During Casting Of 316 Stainless Steel Based Alloys As A Function Of Chromium And Nickel Composition, Abhishek Chitradurga Ranganath

All Theses

By the 1990s, computational methods were beginning to be used to study dislocation density in mental casting. Prior to that time research was based heavily on laboratory studies. This move was encouraged by the need to overcome limitations that experimental approaches had, including high costs and time-consuming processes, and needs of researchers to understand atomic-scale phenomena. Computational techniques allow complex materials to be simulated in cost effective way and can provide insight into behaviour that could never be determined through experimental methods alone.

This work utilized molecular dynamics (MD) simulations along with machine learning approaches to examine the dislocation density …

Influence Of Hygrothermal Conditions Of The Bistability Of Asymmetric Carbon Fiber Laminate Composites, Celia Hill

All Theses

Carbon fiber-reinforced polymer (CFRP) laminates have widespread use in many industries because of their exceptional strength-to-weight ratio. Carbon fiber laminates following an asymmetric layup orientation can exhibit bistability meaning the laminate can exist at two stable geometric configurations. The morphing characteristics of bistable CRFP has a growing level of interest because of its potential in various applications including space aircraft structures for easy repair, automotive structures for energy dissipation and ergonomics, robotics for flexible motion and energy harvesting. Existing research shows that both moisture and temperature affect the material properties and behavior of CFRP laminates, however, the influence of moisture …

Multiphysics Modeling And Experimental Validation Of High-Strength Steel In Laser Powder Bed Fusion Process, M. Rangapuram, S. Babalola, J. W. Newkirk, L. N. Bartlett, F. W. Liou, K. Chandrashekhara, Stephen R. Cluff

Materials Science and Engineering Faculty Research & Creative Works

Laser powder bed fusion (LPBF) is a subset of the additive manufacturing process in which a laser beam selectively joins the metal powder into a desired part in a sequential layer process. Owing to its complex nature of rapid heating and cooling of the melt pool, there is a need to understand the melt pool behavior and its effects on the final manufactured part. a densely packed powder bed is highly desirable for fabricating a superior part using the LPBF process. in this work, discrete element model was used to generate powder beds with realistic powder properties and various factors …

The Use Of Two-Dimensional Detectors For Snapshot And High Accuracy Imaging Ellipsometry, Jeremy A. Vanderslice

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Ellipsometry is a powerful and sensitive optical technique used to characterize thin film thickness and optical properties by measuring changes in the polarization state of light upon reflection or transmission. This dissertation investigates novel ellipsometry configurations that use two-dimensional detectors to enhance measurement speed, spatial resolution, or accuracy of ellipsometry measurements. The study involves the development of three different ellipsometry configurations, encompassing mechanical prototypes, mathematical models, and test measurements to evaluate each system.

Advisor: Jeffrey Shield

Comparing Continuum And Direct Fiber Models Of Soft Tissues: An Ocular Biomechanics Example Reveals That Continuum Models May Artificially Disrupt The Strains At Both The Tissue And Fiber Levels, Xuehuan He, Mohammad R. Islam, Fengting Ji, Bingrui Wang, Ian A. Sigal

Mechanical Engineering Faculty Publications

Collagen fibers are the main load-bearing component of soft tissues but difficult to incorporate into models. Whilst simplified homogenization models suffice for some applications, a thorough mechanistic understanding requires accurate prediction of fiber behavior, including both detailed fiber-level strains and long-distance transmission. Our goal was to compare the performance of a continuum model of the optic nerve head (ONH) built using conventional techniques with a fiber model we recently introduced which explicitly incorporates the complex 3D organization and interaction of collagen fiber bundles [1]. To ensure a fair comparison, we constructed the continuum model with identical geometrical, structural, and boundary …

Biaxial Strain Tuned Upconversion Photoluminescence Of Monolayer Ws2, Shrawan Roy, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Monolayer tungsten disulfide (1L-WS₂) is a direct bandgap atomic-layered semiconductor material with strain tunable optical and optoelectronic properties among the monolayer transition metal dichalcogenides (1L-TMDs). Here, we demonstrate biaxial strain tuned up conversion photoluminescence (UPL) from exfoliated 1L-WS₂ flakes transferred on a flexible polycarbonate cruciform substrate. When the biaxial strain applied to 1L-WS₂ increases from 0 to 0.51%, it is observed that the UPL peak position is redshifted by up to 60 nm% strain, while the UPL intensity exhibits exponential growth with the up-conversion energy difference varying from − 303 to − 120 meV. The measured …

Uncovering Upconversion Photoluminescence In Layered Pbi2 Above Room Temperature, Sharad Ambardar, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

As a van der Waals (vdW) layered semiconductor material, lead iodide (PbI2) possessing a direct bandgap with strong photoluminescence emission in visible range has gained wide attention in applications of photonic and optoelectronic devices. Here, up conversion photoluminescence (UPL) in exfoliated PbI2 flakes is demonstrated at room temperature and elevated temperatures. The linear power dependence of UPL emission with 532 nm excitation suggests the one-photon involved multiphonon-assisted UPL emission process, which is revealed by the temperature-dependent UPL emission measurement. Meanwhile, the nonlinear power dependence of UPL emission with 561 nm excitation indicates the transition of UPL emission mechanism from linear …

Fpga-Based Sensors For Distributed Digital Manufacturing Systems: A State-Of-The-Art Review, Laraib Khan, Sriram Praneeth Isanaka, Frank Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The combination of distributed digital factories (D2Fs) with sustainable practices has been proposed as a revolutionary technique in modern manufacturing. This review paper explores the convergence of D2F with innovative sensor technology, concentrating on the role of Field Programmable Gate Arrays (FPGAs) in promoting this paradigm. A D2F is defined as an integrated framework where digital twins (DTs), sensors, laser additive manufacturing (laser-AM), and subtractive manufacturing (SM) work in synchronization. Here, DTs serve as a virtual replica of physical machines, allowing accurate monitoring and control of a given manufacturing process. These DTs are supplemented by sensors, providing near-real-time data to …

Alteration Of Peripheral Cytokines In Alzheimer’S Disease, Zhengshi Yang

UNLV Theses, Dissertations, Professional Papers, and Capstones

Alzheimer’s disease (AD) is a progressive neurodegenerative disease with the clinical symptoms of gradual cognitive decline and memory loss. Biologically, abnormal accumulation of Aβ (Aβ) plaque and tau tangles in the brain are the core pathological hallmarks in AD. Although inflammatory response is not specific to AD, emerging evidence suggests that the disrupted innate immune system within the central nervous system, particularly microglial activation, might act as the bridge linking Aβ aggregation to pathological phosphorylation and aggregation of tau. The inflammatory response was suggested to initially have a neuroprotective role of attempting to clear Aβ plaques, and then become neurotoxic …

Hitch Cart “Landing Gear”, Rebekah White, Jose Raygoza, Randy Hernandez, Brandon Leon

Mechanical Engineering

This report aims to allow our sponsor, to review our design process of the Hitch Cart Landing Gear Prototype. In the design overview section of this report, we discuss the primary design modifications we made to the wheel mechanism of the existing hitch cart prototype, including the addition of the ACME screws and the folding brackets. This allows our sponsor to see the intended improvements made to the past prototype and understand the primary goal of our project. Then, in the implementation section, we cover the entire manufacturing process to allow our sponsor to understand what manufacturing steps must be …

Pseudo Gps For Romi, Emmanuel Baez, Owen Guinane, Gabriel Coria, Conor Schott

Mechanical Engineering

The Pseudo-GPS system for Romi robots addresses the need for precise real-time location tracking in Cal Poly's Mechatronics lab. This project, developed by Emmanuel Baez, Gabriel Coria, Owen Guinane, and Conor Schott, under the guidance of instructor Charlie Refvem, provides a proof-of-concept system to enhance the Romi robots' geolocation capabilities for advanced robotic algorithms.

The proposed system uses a Raspberry Pi 4 equipped with a Pi camera module and ArUco markers to track the position and orientation of Romi robots within a lab environment. Custom 3D-printed stands secure markers on the robots, and a designated origin marker defines the coordinate …

Expandable And Retractable Wheel Design, Ethan Fortenberry, Emily Cottrell, Keegan Martin, Benjamin Mcconnell

Mechanical Engineering

Our sponsor, Jeremy Goren, wants to see his patented expandable wheel design come to life. He requires a functional final product actuated by linear actuators and with a continuous, circular outer shell. The overall design can be broken up into 2 parts: the inner hub and outer shell. The wheel's shell will consist of a 12-piece outer shell that guides the 6 inner shell pieces. The outer shell pieces will be connected via a UBracket. The hub will consist of 3 identical parts that will hold 2 linear actuators each. The pieces will be bolted together to create 1 singular …

The Waterbug: Adaptive Paddle Board Frame, Remy James Elio Lacchia, Katie Kellum, Madeline Evenson, Shelbi Sullaway

Mechanical Engineering

People with disabilities, particularly wheelchair users, face limitations in participating in outdoor activities like paddleboarding. Central Cal Adaptive, a nonprofit organization, aims to bridge this gap by offering adapted paddleboarding experiences. However, their current paddleboard presents challenges such as portability, range of motion, stability, and safety. Our team, comprising Madeline Evenson, Remy Lacchia, Katie Kellum, and Shelbi Sullaway, has collaborated with Central Cal Adaptive to refine the existing paddleboard design. The team’s goal is to enhance the paddleboard's functionality to better cater to wheelchair users' needs, ensuring lightweight, portable, and safe features for an improved outdoor experience.

Our paddleboard concept …

Piston Crown Design, Kurt L. Lippmann, Liam T. Janssen, Alex Rangel, Larry J. Davis

Mechanical Engineering

This project investigates the effects of dimpling a piston crown, and its impact on engine combustion dynamics. Through computational methods, the effects of piston crown dimpling on flow characteristics were evaluated. Theoretical results were verified with experimental methods. Experimental methods included characterization of exhaust gas content, engine horsepower and torque, and exhaust opacity.

Swim Fly Drone, Alia Wolken, Sha'anan Levy, Andrew Jwaideh, Eduardo Santos

Mechanical Engineering

This project addresses the need for a versatile drone that is capable of operation in both air and water environments, with potential applications in infrastructure inspection, defense, search and rescue, and ocean exploration. This project focuses on the design and development of a waterproof aerial drone capable of floating on the water surface and submerging underneath to controlled depths with the integration of a custom detachable buoyancy chamber. The buoyancy chamber design utilizes syringes to compress and decompress air inside of the chamber, changing the volume of the chamber, with an actuation system controlled by a closed-loop control system that …

Development Of A Manifold Microchannel Heat Sink For The Electrification Of Aircraft, Joshua Mora Sanchez

Mechanical Engineering Undergraduate Honors Theses

The miniaturization of microprocessors and power electronics is leading to critical thermal management challenges. For instance, the heat flux generated in modern computer chips is at the order of 100W/cm², which is well beyond the limit of air cooling. This high heat generation can cause a variety of thermal or mechanical failures in electronic devices. As such, there is a pressing need to devise effective cooling strategies for these microelectronic devices. Liquid cooling with microchannel heat sinks is a promising technology for high power loads. Nevertheless, traditional heat sinks with straight microchannels suffer from two critical challenges: high pressure drop …

Neodymium Doped Zinc Oxide Based Advanced Flexible Piezoelectric Energy Harvester And Self-Powered Biomotion Sensor, Muhtasim Ul Karim Sadaf, Abu Musa Abdullah, Haimanti Majumder, Sk Shamim Hasan Abir, Mariana Torres, Karen Lozano, Md. Wasikur Rahman, M. Jasim Uddin

Mechanical Engineering Faculty Publications

Flexible piezoelectric devices have garnered a lot of attention for their potential as energy harvesters and transducers. In this work, Neodymium (Nd) doped Zinc Oxide (ZnO) based flexible piezoelectric energy harvester and sensory device has been developed. Nd-doped ZnO has been synthesized using wet chemical co-precipitation and incorporated in Polyvinylidene Difluoride (PVDF) polymer matrix along with Multiwalled Carbon Nanotubes (MWCNT) to produce flexible piezoelectric films. The piezoelectric output of the device is tested at variable tapping frequency (60 to 240 BPM) and pressure (10 to 40 psi). The device has also been tested with conventional electronics like bridge rectifiers, capacitors, …

Investigation Ionic Polymer Metal Composite Capacitors Through Fabrication, Experimentation, And Modeling, Liya S. Napollion

UNLV Theses, Dissertations, Professional Papers, and Capstones

The increasing demand for greater energy storage capacity alongside the need to minimize the size of various devices, such as hybrid electric vehicles, medical devices, and pulsed power systems—has highlighted the necessity for advanced polymer film capacitors with high energy density. While traditional batteries and electronic devices have generally sufficed for many applications, their inherent size limitations hinder their ability to deliver the high levels of peak power required for certain demanding applications. This shortfall highlights the critical ongoing challenge within the energy storage sector to improve technology and more effectively meet these growing power requirements. Flexible Ionic Polymer Metal …

Primary And Secondary Resonances Of Fringe Effect Electrostatically Actuated Mems Cantilever Resonators, Miguel Armando Martinez

Theses and Dissertations

The nonlinear dynamics of micro-electromechanical system (MEMS) cantilever resonators actuated by the fringe field at parametric and primary resonances are studied. Three models are used based on different descriptions of the system capacitance. In the fringe and capacitance models, the electrostatic force due to the parallel-plate capacitance is neglected due to a hole in the ground plate (removes overlapping area). The SolidWorks model is based on numerical capacitance simulations performed on SolidWorks using EMS. All three models that approximate the fringe field capacitance are compared with one another. The Method of Multiple Scales (MMS) and Reduced Order Model (ROM) up …

Resonances Of Electrostatically Actuated Non-Uniform Mems Cantilever Resonator Of Constant Width And Linearly Varying Thickness, Rigoberto Flores

Theses and Dissertations

In this investigation the behavior of an electrostatically actuated non-uniform microelectromechanical (MEMS) cantilever resonator of constant width and linearly varying thickness is investigated. The cantilever resonator vibrates using soft AC voltage at near half the first natural frequency of the cantilever and near the first natural frequency of the cantilever, known as primary and parametric resonances, respectively. Bifurcation diagrams for the amplitude-frequency and amplitude-voltage response are obtained for both resonances. Two methods are used in this investigation, namely the Method of Multiple Scales (MMS) and Reduced Order Model (ROM) using up to 6 modes of vibration.

These methods are used …

Thermal Conductivity Characterization Of High Oleic Vegetable Oils Based Hybrid Nanofluids Formulated Using Gnp, Tio2, Mos2, Al2o3 Nanoparticles For Mql Machining, Anthony Chukwujekwu Okafor, Tobechukwu Kingsley Abor, Saidanvar Esanjonovich Valiev, Ignatius Echezona Ekengwu, Abiodun Saka, Monday Uchenna Okoronkwo

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents the results of thermal conductivity characterization of six high oleic soybean oil (HOSO) and four high oleic canola oil (HOCO)-based hybrid nanofluids formulated with four types of nanoparticles (Graphene nanoplatelet (xGnP), TiO2, MoS2, and Al2O3) at nanoparticles wt.% concentration from 1 % to 7 % in 1 % increment using the two-step method for use in MQL machining of difficult-to-cut metals. Thermal conductivity of the formulated hybrid nanofluids were measured using Thermtest Transient Hot Wire Liquid Thermal Conductivity Meter at temperatures from 25 °C to 75 °C in increment of 10 °C. Obtained results showed that thermal …

Finite Element Analysis And Verification Of Transverse Mechanical Properties Of Generally Cylindrical Orthotropic Constitutive Modeling Of 3-Phase Nanocomposite Unit Cell, Christopher J. Hawkins

Master's Theses

Fiber-reinforced composites are increasingly popular due to their specific strength and stiffness, making them ideal for high-performance applications. However, these materials primarily exhibit superior properties in-plane, while their out-of-plane characteristics remain comparatively weaker. Previous research has shown that the most effective method to enhance out-of-plane properties involves the incorporation of carbon nanotubes. Experimental tests have demonstrated significant improvements in properties such as tension, flexural, short beam shear, and fracture toughness. Alongside these experimental studies, analytical equations have been developed to predict the behavior of these composites under various loading conditions, including tension, bending, shear, and fracture. Existing models primarily address …

Investigating Challenges Of Converting Cad Models To Game Ready Assets, Vathsa Pawar

All Theses

This thesis explores the challenges associated with converting detailed CAD models into game-ready assets optimized for use in virtual reality (VR) environments using game engines, focusing on enhancing using mechanical engineering models. The primary goal is to establish a toolchain that allows the integration of CAD models into game engines for immersive applications, enabling engineers and stakeholders to interact with 3D models in a synthetic environment. The study employs several test cases ranging from simple door models to complex automotive vehicle prototypes, elaborating the process of exporting CAD models through intermediate formats (such as STEP, STL, GLB) using tools like …

End-To-End Learning For A Low-Cost Robotics Arm, Abhishek Chothani

Theses and Dissertations

Robotic manipulation is a cornerstone of automation, with the ultimate goal of developing versatile systems capable of executing a wide range of real-world tasks autonomously. Traditional robotics approaches, while reliable and widely adopted in industrial settings, often struggle with adaptability, perception, and dynamic task execution. This thesis explores the evolution from classical robotics techniques to modern learning-based approaches, leveraging advancements in artificial intelligence to overcome these limitations.

Initially, the thesis presents a pick-and-place pipeline built using the Drake robotics framework and the KUKA iiwa robotic arm. This system employs a pseudoinverse controller for inverse kinematics to perform structured tasks like …

Fabrication And Performance Of Scalable Bio-Engineered Porous Layers For Efficient Co2 Capture, Mary Sharon Rose Bondugula

Theses and Dissertations

This dissertation addresses the critical challenge of mitigating climate change by advancing CO2 capture technologies. As global CO2 emissions continue to rise, effective methods for capturing and separating CO2 from industrial processes are essential to combat climate change. Existing CO2 capture systems, such as Pressure Swing Adsorption (PSA) and Temperature Swing Adsorption (TSA), often rely on packed bed designs that face limitations, including poor heat and mass transfer, slow gas diffusion, and low thermal conductivity, reducing their efficiency. To overcome these challenges, this dissertation explores innovative solutions by developing advanced adsorbent coatings and scalable bed configurations.

This research begins by …

Fabrication And Charcaterization Of Pullulan-Collagen Nanofibers Via Forcespinning, Valeria Leon Leal

Theses and Dissertations

Extensive research on collagen has spurred advancements in tissue engineering and biomaterial development, given collagen´s pivotal role in regulating various tissue structures across diverse organisms. This study delves into fabricating nanocomposites utilizing collagen, along with silver nanoparticles, chondroitin sulfate and pullulan, for potential applications in antibacterial medical devices, and cell regeneration. Collagen, abundant in the extracellular matrix, provides essential structural support, while silver nanoparticles and chondroitin confer antimicrobial properties, crucial for combating infections. Pullulan, a polysaccharide polymer, serves as a biocompatible carrier for silver nanoparticles whilst being the starting nanofiber forming material. Utilizing Forcespinning® technology, composite nanofibers were successfully synthesized. …

Synthesis Of Materials For Additive Manufacturing Of Enhanced Polymers And Textured Ceramics, Diana Fontes

Open Access Theses & Dissertations

This research will be divided into two sections. The first section investigates the development of textured Barium Titanate (BaTiO3) ceramics fabricated through Direct Ink Write Printing (DIW) integrated with Templated Grain Growth (TGG). This approach aims to develop lead-free piezoelectric materials with grain alignment during printing process to promote high piezoelectric performance comparable to those in lead-based ceramics. This research evaluates the impact of the DIW-TGG process on grain orientation, material densification, and piezoelectric response, illustrating its potential for developing high-performance ceramics for advanced applications such as sensors, actuators, and other piezoelectric devices. The second project explores the chemical stability …

Vertically Aligned Nickel Cobalt Molybdenum Copper Oxide Nanotubes For High Performance Asymmetric Supercapacitors, Ricardo Herrera Aguirre

Open Access Theses & Dissertations

Designing materials having novel multi metal oxide electrodes with controlled structure and composition is a critical technological challenge for high performance supercapacitor applications. Quaternary metal oxides have attracted considerable attention in this field, where many methods have been used to improve their performance. In the present work, the nickel cobalt molybdenum copper oxide (NCMCuO2) has been synthesized using a hydrothermal method. The effect of different concentrations of Cu doping (0.5%,1.0% and 2.0%) on the NCM frame and structural and electrochemical properties of the quaternary metal oxide (NCMCuO2) are studied thoroughly. The XRD pattern of synthesized NCMCuO2 exhibited predominant (002) orientation …