Mechanical Engineering Commons^™

Investigative Research On Design Parameters And Criticality Models For Microreactors, Cameron Jensen

UNLV Theses, Dissertations, Professional Papers, and Capstones

With increased energy demand and the desire to reduce reliance on fossil fuels, nuclear power will need to play a prominent role in achieving carbon-free energy independence. Large nuclear reactors are necessary to meet this objective. However, they are expensive and take a long time to build. For remote locations (e.g., military bases) and smaller communities, large nuclear reactors would not be feasible or cost effective. Small reactors (microreactors) can fill this necessary gap. These reactors would be factory-built, delivered quickly, and operated with high intrinsic levels of safety. With microreactors still in conceptual and testing states, there is a …

Novel Designs Of Soft Tactile Sensor And Robot Finger Manipulator Based On Optical Fibers., Seokyoung Han

Electronic Theses and Dissertations

Robotic manipulation is one of the main types of automated labor that humans want to achieve in order to free ourselves from mundane and hazardous tasks. The range of realizations could be very broad, from massive industrial robots to highly advanced medical devices for human healthcare. Given the critical nature of these application spaces, they require robust, safe, and most of all versatile designs. In that direction, one of the most interesting topics is the anthropomorphic robotic manipulator. Since it is inspired by human hands’ function and structure, it is able to achieve the aforementioned system requirements. However, the perfect …

Electrokinetic Particle Trapping Performance Of Conductive Nanofiber Mats In Microfluidic Wells., Jacob Hunter West

Electronic Theses and Dissertations

The frequency dependence of electrokinetic particle trapping using large-area (>mm²) conductive carbon nanofiber (CNF) mat electrodes is investigated. The fibers provide nanoscale geometric features for the generation of high electric field gradients, which is necessary for particle trapping via dielectrophoresis (DEP). A device was fabricated with an array of microfluidic wells for repeated experiments; each well included a CNF mat electrode opposing an aluminum electrode. Fluorescent microspheres (1 µm) were trapped at various electric field frequencies between 30 kHz – 1 MHz. Digital images of each well were analyzed to quantify particle trapping. DEP trapping by the …

Barocaloric Heat Pumps Based On Soft Materials., Naveen Weerasekera

Electronic Theses and Dissertations

Solid-state refrigeration offers a promising alternative to traditional vapor compression systems that are relatively inefficient, unreliable, and have a high global warming potential. Various solid-state cooling technologies, including those based on electrocaloric, magnetocaloric, and elastocaloric effects have been investigated in the recent past. However, concerns regarding their efficiency, scalability and cost remain. Refrigeration and heat pump technologies based on the barocaloric effect (temperature/entropy change due to hydrostatic pressure) hold great promise but have received comparatively less attention. Barocaloric heating/cooling based on low cost, compressible soft materials with large barocaloric response have the potential to pave the way for efficient, scalable, …

A Computational Framework For Predicting Cell-Specific Nucleo-Cytoskeletal Forces, Madison Leigh Goldfeldt

Boise State University Theses and Dissertations

Understanding the influence of mechanical forces on cell function and fate is crucial in unraveling the intricate mechanisms that govern cellular behavior. The cytoskeleton, a dynamic network of protein filaments, plays a pivotal role in sensing and transmitting mechanical cues within cells. The nucleus relies on cytoskeletal mechanical input through nuclear envelope adaptor proteins to sense external stimuli and respond by regulating intra-nuclear chromatin organization. This research provides a means for examining the interplay between mechanical forces and the cytoskeleton in regulating various cellular processes, including cell adhesion, migration, division, and differentiation. Through studying and simulating the cellular response to …

Porcine Computational Modeling To Investigate Developmental Dysplasia Of The Hip, Chia-Yu Yu

Boise State University Theses and Dissertations

While it is well-established that early detection and initiation of treatment of developmental dysplasia of the hip is crucial to successful clinical outcome, research on mechanics of the hip joint during healthy and pathological hip development in infants has been limited. Quantification of mechanical behavior in both the healthy and dysplastic developing joints may provide insight into the causes of developmental dysplasia of the hip and facilitate innovation in treatment options. In this study, subject-specific three-dimensional finite element models of two pigs were developed: one healthy pig and one pig with induced dysplasia in the right hindlimb. The objectives of …

Thermal-Fluid And Optical Considerations In The Design Of Porous Cavity Receivers, Koda D. Boldt

Boise State University Theses and Dissertations

Concentrated solar power (CSP) is a versatile renewable energy source that cleanly provides thermal energy by means of concentrating solar irradiance. One form of CSP, central receiver systems (CRS), utilizes receivers that allow for a solid medium to act as a heat exchanger between the solar irradiance and an optically clear working fluid. This solid medium can take many forms. One such form that shows great potential in high temperature applications is a porous receiver made of a ceramic material. The porous media is subject to solar irradiance to heat its surface. Air is then pulled across the porous media …

Synthesis Of Durable Zeolite 13x Insertion Coatings And Scaled-Up Experimental Demonstration For Co2 Capture, Daniel Jamil Hocheimy

Theses and Dissertations

Minimizing the energy requirement for capturing carbon dioxide (CO₂) from post-combustion sources is critical to efficient industrial decarbonization and subsequent mitigation of the effects of climate change. The current portfolio of CO₂ capture technologies includes absorption, membrane separation and packed bed adsorption, which suffer from high energy and temperature requirements, scalability, and location dependency issues. Adsorption-based systems could cater to these concerns; however, their current embodiments primarily use packed adsorbent bed design and electricity-driven vacuum pumps to regenerate them. While simple and easy to fabricate, these designs are not scalable and cannot use heat to regenerate them …

Test And Evaluation Model For Midwater Docking Of Autonomous Underwater Vehicles, Parker Baillon

Theses and Dissertations

This research created a Test and Evaluation (T&E) model for midwater Autonomous Underwater Vehicle (AUV) capture. The creation of this model will allow for a better assessment of the feasibility of midwater AUV capture. To achieve this, the T&E model was exposed to various flow conditions to assess stability. Capturing an AUV in midwater, the area below the wave-affected zone to the sea floor, has many benefits for an AUV and its mission. AUVs basing missions from a midwater dock will not be affected by wave motions. A midwater dock can be transported to any mission site and deployed with …

Study Of Electrospun Nanocomposite Nanofiber Nonwoven Mats With Precursor Solutions Prepared By Ultrasonic Processing, Stephanie Tussey

All Dissertations

Understanding the complexity of changes in a polymer solution through the addition of nanoparticles and the process used to prepare the solutions is vitally important to obtain desirable characteristics of electrospun nanofibers such as degree of crystallinity, morphological, thermal and mechanical properties. Although there have been significant efforts in this research area, a more in-depth understanding on how nanoparticles can affect the formation of polymeric structures during electrospinning is still needed to ensure overall quality and performance of the nonwoven material. The present study aimed to specifically explore the relationship between solution processing method, nanoparticle volume fraction, and solution properties …

A Manufacturing-To-Response Pathway For Manufacturing Optimization Of Carbon Fiber Reinforced Polymer Composite Structures, Madhura Limaye

All Dissertations

Over the past decade, there has been an increased adoption of thermoplastic and thermoset based continuous carbon fiber reinforced polymer (CFRP) composites for structural applications in several industries. Among the different manufacturing methods, thermoforming process for thermoplastic based continuous CFRP’s offer a major advantage in reducing cycle times for large scale productions. Similarly, out-of-autoclave curing process for thermoset based continuous CFRP’s using heated tooling enables production of large composite structures. However, these manufacturing processes can have a significant impact on the structural performance of parts by inducing undesirable effects. These effects include inhomogeneous fiber orientations, thickness variations, and residual stresses …

Oscillations Of Capillary Surfaces With Volume And Edge Effects, Dingqian Ding

All Dissertations

Capillary surfaces are defined by an interface endowed with surface tension that is partially supported by a solid substrate and are susceptible to oscillations reflecting a balance between fluid inertia and the restorative force of surface tension. The wave dynamics strongly depend upon volume change within the domain and edge effects through the boundary conditions applied at the contact-line formed at the liquid-gas-solid interface, while the spatial wave structure conforms to the geometry of the capillary surface. This dissertation develops mathematical models to address these effects for several canonical capillary surfaces, which are organized into two parts that are focused …

Advances In Nanofiber Technology For Biomedical Application: A Review, Dipasree Bhowmick, Islam Uddin Shipu

Mechanical Engineering Faculty Publications

The application of nanofiber technology in the biomedical field has garnered significant interest due to its potential to revolutionize areas such as tissue engineering, wound healing, and antimicrobial treatments. This paper provides a comprehensive review of the recent advancements in nanofiber technology, particularly focusing on electrospinning and 3D printing methods that enable the fabrication of scaffolds mimicking the native extracellular matrix. These technologies have facilitated the development of nanofibers with high surface-to-volume ratios, adjustable porosity, and enhanced mechanical properties, tailored to meet specific biomedical needs. Despite their promising features, challenges such as the optimization of pore size for effective cell …

Mechanical Properties And Microstructure Of Multi-Materials Fabricated Through A Combination Of Lpbf And Ded Additive Manufacturing Techniques, Christopher J. Bettencourt

All Graduate Theses and Dissertations, Fall 2023 to Present

This research explores the use of different metals combined through 3D-printing to enhance the performance of materials, with a focus on making heat exchangers more cost-effective for renewable energy. The goal is to replace a costly high-temperature alloy with a more affordable low-temperature alloy, using metal additive manufacturing for its benefits such as less material waste, faster production, reduced weight, and the ability to print entire assemblies in one go. The study delves into a unique combination of two 3D-printing techniques, Directed Energy Deposition and Laser Powder-Bed Fusion, to create a multi-material composed of stainless steel 316L and a nickel-based …

Development, Modeling, Identification, And Control Of Tilt-Rotor Evtol Aircraft, Clayton T. Spencer

All Graduate Theses and Dissertations, Fall 2023 to Present

This thesis includes the development, modeling, identification, and control of an electric-Vertical-Take-Off-and-Landing (eVTOL) aircraft with tiltable rotors. The front two rotors have tilting capability for transition flight from vertical-take-off to forward-level flight. This work details the development of an eVTOL aircraft and the selection of sub components such as electric motors, batteries, and controllers. After the aircraft build, mathematical model is derived to describe the motion of the aircraft. Unknown parameters in the mathematical model are identified using a Least-Squares-regression (LSR) method that can handle parameter constraints. This is done using real flight data collected from the aircraft. Lastly, this …

Fabrication And Performance Demonstration Of Compact Adsorption Heat Pump, Faraz Ege

Theses and Dissertations

Addressing global environmental concerns requires a shift to eco-friendly energy sources, particularly in cooling applications where traditional vapor-compression systems rely on harmful refrigerants and electricity. Thermally-driven cooling systems, like adsorption heat pumps, offer promise with their environmentally friendly refrigerants such as water and use of low-temperature heat sources, including solar energy or waste industrial heat. This dissertation undertakes a comprehensive investigation into the development and optimization of compact adsorption heat pumps, aiming to address the efficiency and environmental challenges inherent in conventional cooling systems.

This research begins by introducing a novel insertion coating technique for fabricating MIL-101 (Cr) adsorbent layers …

Experimental And Numerical Analysis Of Laminar And Transitional Flow Through Annular Corrugated Pipes, Joseph Russell Sargent

Theses and Dissertations

This dissertation presents studies on pressure loss through annular corrugated pipes to determine a friction factor coefficient using nitrogen. Ten different corrugated pipes’ geometries were evaluated via testing and experimentation. The ratio of corrugation height to inner diameter varied from 0.233 to 0.333 and the ratio of corrugation pitch to inner diameter varied from 0.181 to 0.446. Nitrogen flow rates between 0.25 to 94.4 standard liters per minute were used, resulting in Reynolds numbers, based on the corrugated pipe inner diameter, from 100 to 23,000. The experimental set-up was validated using smooth-pipe pressure loss measurements and the derived friction factor …

System Identification For Motion Control Of Unmanned Aerial Vehicles Platform, Raj Ramesh Agarwal

Theses and Dissertations

Comprehensive research on Unmanned Aerial Vehicles (UAV) system identification for motion control parameters is presented in this thesis, with a focus on the necessity of precise control and improved performance. Using Pseudorandom Binary Sequence (PRBS) and Normally Distributed Random Numbers, it presents a unique technique for excitation of UAV dynamic systems. It also shows how effective random signals are in time-domain identification for precise control in a range of flying circumstances. The piece of research includes a thorough analysis and implementation of various approaches and its further improvements, highlighting the benefits and drawbacks of each. These approaches include the free …

Sliding Markov Decision Processes For Dynamic Task Planning On Uncrewed Aerial Vehicles, Trent Wiens

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Mission and flight planning problems for uncrewed aircraft systems (UASs) are typically large and complex in space and computational requirements. With enough time and computing resources, some of these problems may be solvable offline and then executed during flight. In dynamic or uncertain environments, however, the mission may require online adaptation and replanning. In this work, we will discuss methods of creating MDPs for online applications, and a method of using a sliding resolution and receding horizon approach to build and solve Markov Decision Processes (MDPs) in practical planing applications for UASs. In this strategy, called a Sliding Markov Decision …

Dynamic Impact Testing And Numerical Analysis Of Non-Proprietary Astm F2656-20 M50 Anti-Ram Barrier Components, Weston Kelley

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

In a post-9/11 world, hostile actors are using vehicles as weapons to inflict civilian casualties. Pedestrians, vulnerable road users, military personnel, and police may be targeted using a vehicle as a weapon. The United States Department of Defense (DoD) also utilizes Entry Control Facilities (ECFs) which are carefully designed transportation corridors to manage how threat vehicles are able to access military facilities. In 2004, DoD started to upgrade all ECFs using both passive and active barriers. Many anti-ram vehicle barriers were evaluated according to the criteria established in ASTM F2656, but to date few options are available which are (1) …

The Effect Of Extended Saltwater Absorption And Uv Cure On The Compressive Properties Of Msla 3d-Printed Photopolymer Resin Samples With Printing Variations, Suzanne Dixon

Theses and Dissertations

Liquid Crystal Display (LCD) 3D printers, also known as Masked Stereolithography Apparatus (MSLA), is a type of vat polymerization printing technique that cures liquid resin into a solid object. This technique is relatively new. Consequently, there is a shortage of detailed research on the impact of long-term environmental exposure on the MSLA-printed materials. The research within this document informs engineers and scientists of resin compressive properties after extended exposure to saltwater and ultraviolet (UV) light. Saltwater absorption of the material was analyzed at atmospheric pressure, 30-psi, 60-psi, and 90-psi; the samples reached saturation in saltwater after 56 days. The variation …

Computational Fluid Dynamics Study Of Perforated Monopiles, Mary Kathryn Walker

Theses and Dissertations

Monopiles are used in the construction of offshore wind turbines and typically have a design life of 25 to 50 years. Over their lifecycle, monopiles are exposed to a corrosive saltwater environment, facilitating a galvanic oxidation process that quickly degrades the structure. This process can be mitigated by coating the monopile in a protective barrier and implementing cathodic protection techniques. Historically, monopile designers assumed the interior of the pile would be completely sealed and the galvanic corrosion process would eventually consume all the available oxygen, halting the reaction. However, penetrations made in the pile wall for conduit often leaked and …

Heat Sink Integrating Phase Change Materials (Pcms) For Cooling High Power Electronic Devices, Mohammad Sameer Qasem

Theses

This research explores the numerical analysis of phase change materials (PCMs) heat sinks, focusing on high heat flux dissipation applications, e.g. electronics cooling. Both 2D and 3D numerical models using gallium and paraffin RT31 as PCMs are considered within a heat sink design framework featuring a rectangular cavity and dual opposing vertical copper walls serving as fins to dissipate heat from the hot sink base that receives heat from the heat source. The inclusion of a Triply Periodic Minimal Surface (TPMS) ‘Primitive’ structure as an in-fill thermal conductivity enhancer (TCE) in the case of the gallium heat sink, and a …

Emulsion Stability, Rheological Properties, And Combustion Characteristics Of Water-Jojoba Biofuel Emulsion, Ihab Mohamed Helal

Theses

This thesis comprehensively investigates the stability, rheological properties, and engine performance implications of Water in Jojoba Biodiesel (WJBD) emulsion. The research delves into multiple aspects, including the influence of diverse surfactants and water concentrations on emulsion stability. It also yields valuable insights into the development of stable water in jojoba biodiesel emulsions, specifically tailored for diesel engines. These insights contribute significantly to the body of knowledge of positioning emulsion fuels as viable alternative to traditional diesel fuels. The anticipated benefits include notable reductions in emissions, improvement in combustion efficiency, and lower production cost. Importantly, this study underscores the critical importance …

Renewable Energy Misinformation: A Literature Based Approach To Rebutting False Claims, Matthew Ard

McNair Research Journal SJSU

No abstract provided.

Information Model Based On Parameters Of A Combined Soil Preparation Until For Planting, Azmuddin Sadriddinov, Anvar Abdazimov, Faxraddin Mavlanov, Hursand Madrakhim Ugli Rakhimov

Technical science and innovation

The article describes in detail the development of a combined pre-sowing machine as a result of the literature analysis of the scientific research conducted on pre-sowing tillage machines and its use and working process. In addition, the article provides scientifically based information about the factors affecting the leveler-softener and previous work on their improvement. The current state of tillage before planting in Uzbekistan and the size of the tilled fields are studied and tabulated. In order to optimize the parameters of the developed machine and minimize costs, as well as to increase its efficiency, it is devoted to the creation …

Characterizing Brain And Skull Mechanics In The Minipig Using Magnetic Resonance Elastography, Shuaihu Wang

McKelvey School of Engineering Graduate Student Theses & Dissertations

Computational models and simulation are important tools to investigate the mechanisms underlying traumatic brain injury (TBI); their accuracy depends strongly on accurate model parameters, including the mechanical properties of the brain and its interactions with the skull. However, most existing TBI modeling studies are performed using material properties derived from animal tissue obtained after death. Magnetic resonance elastography (MRE) provides a non-invasive method for estimating the mechanical properties of soft tissue. The overall objective of this thesis is to characterize the biomechanical properties of brain tissue and brain-skull interface in the minipig by using MRE. This was achieved through pursuit …

Experimental Analysis Study Wave Drift Force Of Moored Floating Production Units (Fpu), Arifin Rifliansah, Wibowo Harso Nugroho

Makara Journal of Technology

Drift forces caused by sea waves and currents are an important aspect that needs to be studied in planning moored floating structures, especially Floating Production Units (FPU) type ships which are operated for oil and gas exploration. This study describes the drift forces on the FPU which is subjected to environmental loads in the form of waves. The slow-drift movement that occurs in a moored FPU, and experiencing irregular waves is a very important problem. The complexity of determining drift forces analytically and numerically requires the use of hydrodynamics model test. In the model test on a certain model scale …

Optimization Pump As Turbine Coupled To A Self-Excited Induction Generator Using Multi-Objective Genetic Algorithm, Emanuel J. Nyirenda

Tanzania Journal of Engineering and Technology (TJET)

As a way of accelerating the deployment of affordable and clean renewable energy generation technologies, applying a pump working as a turbine coupled to a self-excited induction generator is gaining popularity in various areas including energy recovery and micro hydro systems. However, it is currently challenging to predict the performance of the PAT-SEIG system and there is no agreed-upon rule on the selection of the appropriate system to be installed at a particular site. This paper has presented multi-objective optimization to select the best operating point of the PAT-SEIG system. The results show that the peak efficiencies for the PAT …

Optimal Load Shedding During Service Restoration In Electrical Secondary Distribution Network Based On Reinforcement Learning, Rukia J. Mwifunyi

Tanzania Journal of Engineering and Technology (TJET)

Increased stress in traditional power systems results in blackouts due to voltage instability attributed to a mismatch between available capacity and load demand, especially in distribution networks. Service restoration schemes are designed to return power supply to the affected parts of the networks. The availability of insufficient supply is a complex problem that requires operational experience or an automatic system. The stochastic nature of load demand significantly impacts service restoration as it results in increased restored demand in case a fault occurs during off-peak hours and helps reduce overload if the fault occurs during peak hours. The study adopts an …