Mechanical Engineering Commons^™

Sliding Mode Control Of A Nonlinear Wave Energy Converter Model, Tania Demonte Gonzalez

Dissertations, Master's Theses and Master's Reports

The most accurate wave energy converter models for heaving point absorbers include nonlinearities, which increase as resonance is achieved to maximize energy capture. The efficiency of wave energy converters can be enhanced by employing a control scheme that accounts for these nonlinearities. This project proposes a sliding mode control for a heaving point absorber that includes the nonlinear effects of the Froude-Krylov force. The sliding mode controller tracks a reference velocity that matches the phase of the excitation force to ensure higher energy absorption. This control algorithm is tested in regular linear waves and is compared to a complex-conjugate control …

Development Of Autonomous Vehicle Motion Planning And Control Algorithm With D* Planner And Model Predictive Control In A Dynamic Environment, Somnath Mondal

Dissertations, Master's Theses and Master's Reports

The research in this report incorporates the improvement in the autonomous driving capability of self-driving cars in a dynamic environment. Global and local path planning are implemented using the D* path planning algorithm with a combined Cubic B-Spline trajectory generator, which generates an optimal obstacle free trajectory for the vehicle to follow and avoid collision. Model Predictive Control (MPC) is used for the longitudinal and the lateral control of the vehicle. The presented motion planning and control algorithm is tested using Model-In-the-Loop (MIL) method with the help of MATLAB® Driving Scenario Designer and Unreal Engine® Simulator by Epic Games®. Different …

High Injection Pressure Impinging Diesel Spray Characteristics And Subsequent Soot Formation In Reacting Conditions, Zhihao Zhao

Dissertations, Master's Theses and Master's Reports

The spray impingement in diesel engines attracts the attention of engine researchers in recent decades as the physical size of the engine is reduced. Due to the spray impingement, the atomization, vaporizing and air-fuel mixing quality is altered compared to a free spray. For emission control, soot is one of the major particulate emissions from diesel combustion and its formation in an impinged spray is worthy to be investigated.

Firstly, to understand the impinged spray characteristics, the experiments for both non-vaporizing and reacting conditions were conducted in a constant volume combustion vessel. The impinged spray was captured by a high-speed …

Defect Detection Using Dynamic Analysis For Additive Manufactured Metals, Gita Deonarain

Dissertations, Master's Theses and Master's Reports

Additive manufacturing (AM) has the ability to produce parts with complex geometries and internal features, however, for demanding applications such as the automotive and aerospace industries, it is crucial that the parts can meet the demanding functional and geometric requirements. Quality control for AM parts focuses on nondestructive methods of testing, but many of the current methods are expensive and time-consuming. The research presented in this report explores various methods of nondestructive evaluation (NDE) using dynamic analysis on stainless steel parts produced with selective laser melting (SLM). Methods include, but are not limited to, frequency response functions (FRF), impedance-based measurements, …

Integrated Torrefaction-Extrusion System For Conversion Of Fiber-Plastic Wastes Into Solid Fuels, Shreyas Kolapkar

Dissertations, Master's Theses and Master's Reports

Waste generation is increasing, and a significant portion is being landfilled. In parallel, we are constantly pursuing cleaner fuels due to environmental and regulatory factors. To address both these challenges, torrefaction of wastes to produce clean fuels and feedstock for other thermochemical processes is one of the potential solutions. This work focuses on (a) fundamental understanding of the properties of un-torrefied and torrefied wastes and (b) development of a pilot-scale integrated torrefaction-extrusion system for converting fiber-plastic wastes to solid fuels.

In this study, a 60:40 fiber-plastic waste blend was used for performing extensive experiments on densified and un-densified wastes to …

Toward Intelligent Welding By Building Its Digital Twin, Qiyue Wang

Theses and Dissertations--Electrical and Computer Engineering

To meet the increasing requirements for production on individualization, efficiency and quality, traditional manufacturing processes are evolving to smart manufacturing with the support from the information technology advancements including cyber-physical systems (CPS), Internet of Things (IoT), big industrial data, and artificial intelligence (AI). The pre-requirement for integrating with these advanced information technologies is to digitalize manufacturing processes such that they can be analyzed, controlled, and interacted with other digitalized components. Digital twin is developed as a general framework to do that by building the digital replicas for the physical entities. This work takes welding manufacturing as the case study to …

Nondestructive Evaluation Of Aluminium Foam Panels Subjected To Impact Loading, Gabriella Epasto, Fabio Distefano, Hozhabar Mozafari, Emanoil Linul, Vincenzo Crupi

Department of Mechanical and Materials Engineering: Faculty Publications

Aluminium foam sandwich structures have excellent energy absorption capacity, combined with good mechanical properties and low density. Some of the authors of this paper proposed an innovative Metallic Foam Shell protective device against flying ballast impact damage in railway axles. A closed-cell aluminium foam was chosen for the Metallic Foam Shell device. The main goal of this study was the experimental investigation of the impact responses of aluminium foam panels. Low velocity impact tests were carried out at different energies on different types of aluminium foam panels in order to investigate the effects of some parameters, such as core thickness, …

Surface Strengthening Of Single-Crystal Alumina By High-Temperature Laser Shock Peening, Fei Wang, X. L. Yan, Lei Liu, Michael Nastasi, Yongfeng Lu, Bai Cui

Department of Mechanical and Materials Engineering: Faculty Publications

This manuscript reports a novel process of high-temperature laser shock peening (HTLSP) for surface strengthening of single-crystal ceramics such as sapphire and reveals its fundamental mechanisms. HTLSP at 1200°C can induce a high compressive residual stress on the surface of sapphire while minimize the damage of laser-driven shock waves. Transmission electron microscopy characteriza- tions revealed high dislocation densities near the surface, suggesting that plastic deformation at an ultrahigh strain rate was generated by the high shock wave pressure. The HTLSP-induced compres- sive residual stress can significantly improve the hardness and fracture toughness of sapphire, while maintain its outstanding optical transmittance.

The Role Of Microenvironmental Cues And Mechanical Loading Milieus In Breast Cancer Cell Progression And Metastasis, Brandon D. Riehl, Eunju Kim, Tasneem Bouzid, Jung Yul Lim

Department of Mechanical and Materials Engineering: Faculty Publications

Cancer can disrupt the microenvironments and mechanical homeostatic actions in multiple scales from large tissue modification to altered cellular signaling pathway in mechanotransduction. In this review, we highlight recent progresses in breast cancer cell mechanobiology focusing on cell-microenvironment interaction and mechanical loading regulation of cells. First, the effects of microenvironmental cues on breast cancer cell progression and metastasis will be reviewed with respect to substrate stiffness, chemical/topographic substrate patterning, and 2D vs. 3D cultures. Then, the role of mechanical loading situations such as tensile stretch, compression, and flow-induced shear will be discussed in relation to breast cancer cell mechanobiology and …

Ligand Assisted Growth Of Perovskite Single Crystals With Low Defect Density, Ye Liu, Xiaopeng Zheng, Yanjun Fang, Ying Zhou, Zhenyi Ni, Xun Xiao, Shangshang Chen, Jinsong Huang

Department of Mechanical and Materials Engineering: Faculty Publications

A low defect density in metal halide perovskite single crystals is critical to achieve high performance optoelectronic devices. Here we show the reduction of defect density in per[1]ovskite single crystals grown by a ligand-assisted solution process with 3‐(decyldimethy[1]lammonio)‐propane‐sulfonate inner salt (DPSI) as an additive. DPSI ligands anchoring with lead ions on perovskite crystal surfaces not only suppress nucleation in solution, but also regulate the addition of proper ions to the growing surface, which greatly enhances the crystal quality. The grown CH₃NH₃PbI₃ crystals show better crystallinity and a 23-fold smaller trap density of 7 × 10 …

Social Connectedness And Negative Affect Uniquely Explain Individual Differences In Response To Emotional Ambiguity, Maital Neta, Rebecca L. Brock

Department of Mechanical and Materials Engineering: Faculty Publications

Negativity bias is not only central to mood and anxiety disorders, but can powerfully impact our decision-making across domains (e.g., financial, medical, social). This project builds on previous work examining negativity bias using dual-valence ambiguity. Specifically, although some facial expressions have a relatively clear negative (angry) or positive valence (happy), surprised expressions are interpreted negatively by some and positively by others, providing insight into one’s valence bias. Here, we examine putative sources of variability that distinguish individuals with a more negative versus positive valence bias using structural equation modeling. Our model reveals that one’s propensity toward negativity (operationalized as temperamental …

Direct Numerical Simulation Of A Pulsatile Flow In A Stenotic Channel Using Immersed Boundary Method, Siamak Mirfendereski, Jae Sung Park

Department of Mechanical and Materials Engineering: Faculty Publications

A three-dimensional direct numerical simulation model coupled with the immersed boundary method has been developed to simulate a pulsatile flow in a planar channel with single and double one-sided semicircular constrictions. For relevance to blood flow in large arteries, simulations have been performed at Reynolds numbers of 750 and 1000. Flow physics and resultant wall shear stress (WSS)-based hemodynamic parameters are presented. The instantaneous vortex dynamics, mean flow characteristics, and turbulent energy spectra are evaluated for flow physics. Subsequently, three WSS-based parameters, namely the time-averaged WSS, oscillatory shear index, and relative residence time, are calculated over the stenotic wall and …

Large-Scale Synthesis Of Compressible And Re-Expandable Three-Dimensional Nanofiber Matrices, Alec Mccarthy, Lorenzo Saldana, Daniel Mcgoldrick, Johnson V. John, Mitchell Kuss, Shixuan Chen, Bin Duan, Mark A. Carlson, Jingwei Xie

Department of Mechanical and Materials Engineering: Faculty Publications

Due to their biomimetic properties, electrospun nanofibers have shown great potential in many biomedical fields. However, traditionally-produced nanofibers are typically two-dimensional (2D) membranes limiting their applications. Herein, we report a large-scale synthesis of compressible and reexpandable three-dimensional (3D) nanofiber matrices for potential biomedical applications. The reproducible mass production of such matrices is achieved using a multiple-emitter electrospinning machine with a controlled environment (e.g., temperature, humidity, and air flow rate) followed by an innovative gas-foaming expansion. The modified 20-emitter circular array with 3D-printed needle caps is capable of maintaining stable Taylor cones under extremely high flow rates. The introduction of such …

Assembly Of Close-Packed Ferroelectric Polymer Nanowires Via Interface-Epitaxy With Res2, Dawei Li, Shuo Sun, Kun Wang, Zahra Ahmadi, Jeffrey E. Shield, Stephen Ducharme, Xia Hong

Department of Mechanical and Materials Engineering: Faculty Publications

The flexible, transparent, and low-weight nature of ferroelectric polymers makes them promising for wearable electronic and optical applications. To reach the full potential of the polarization-enabled device functionalities, large-scale fabrication of polymer thin films with well-controlled polar directions is called for, which remains a central challenge. The widely exploited Langmuir–Blodgett, spin-coating, and electrospinning methods only yield polymorphous or polycrystalline films, where the net polarization is compromised. Here, an easily scalable approach is reported to achieve poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) thin films composed of close-packed crystalline nanowires via interface-epitaxy with 1T′-ReS₂. Upon controlled thermal treatment, uniform P(VDF-TrFE) films restructure into …

Reducing Corrosion Of Additive Manufactured Magnesium Alloys By Interlayer Ultrasonic Peening, M. P. Sealy, R. Karunakaran, S. Ortgies, G. Madireddy, A. P. Malshe, K. P. Rajurkar

Department of Mechanical and Materials Engineering: Faculty Publications

Additive manufad (AM) magn alloys corrode rapidly due to tensile stress and coarse microstructures. Cyclically combining (hybridizing) additive manufacturing with interlayer ultrasonic peening was proposed as a solution to improve corrosion resistance of additive manufactured magnesium WE43 alloy through strengthening mechanisms and compressive residual stress. Applying interlayer peening work hardened discrete layers and formed a glocal integrity of regional grain refinement and subsurface compressive residual stress barriers. Tensile residual stress that typically accelerates corrosion decreased 90%. Results showed time-resolved control over corrosion was attainable by interlayer peening, and local corrosion within print cells decreased 57% with respect to as-printed WE43.

Ultra-Fast Charging In Aluminum-Ion Batteries: Electric Double Layers On Active Anode, Xuejing Shen, Tao Sun, Lei Yang, Alexey Krasnoslobodtsev, Renat F. Sabirianov, Michael P. Sealy, Wai-Ning Mei, Zhanjun Wu, Li Tan

Department of Mechanical and Materials Engineering: Faculty Publications

With the rapid iteration of portable electronics and electric vehicles, developing high-capacity batteries with ultra-fast charging capability has become a holy grail. Here we report rechargeable aluminum-ion batteries capable of reaching a high specific capacity of 200 mAh g^−1. When liquid metal is further used to lower the energy barrier from the anode, fastest charging rate of 10⁴ C (duration of 0.35 s to reach a full capacity) and 500% more specific capacity under high-rate conditions are achieved. Phase boundaries from the active anode are believed to encourage a high-flux charge transfer through the electric double layers. As …

Twinning-Assisted Dynamic Adjustment Of Grain Boundary Mobility, Qishan Huang, Qi Zhu, Yingbin Chen, Mingyu Gong, Jixue Li, Ze Zhang, Wei Yang, Jian Wang, Haofei Zhou, Jiangwei Wang

Department of Mechanical and Materials Engineering: Faculty Publications

Grain boundary (GB) plasticity dominates the mechanical behaviours of nanocrystalline materials. Under mechanical loading, GB configuration and its local deformation geometry change dynamically with the deformation; the dynamic variation of GB deformability, however, remains largely elusive, especially regarding its relation with the frequently-observed GB-associated deformation twins in nanocrystalline materials. Attention here is focused on the GB dynamics in metallic nanocrystals, by means of well-designed in situ nanomechanical testing integrated with molecular dynamics simulations. GBs with low mobility are found to dynamically adjust their configurations and local deformation geometries via crystallographic twinning, which instantly changes the GB dynamics and enhances the …

Predictive Maintenance Of Bearing Machinery Using Simulation- A Bibliometric Study, Karan Gulati Mr., Keshav Basandrai Mr., Shubham Tiwari Mr., Pooja Kamat Prof., Satish Kumar Dr.

Library Philosophy and Practice (e-journal)

Modelling is a way of constructing a virtual representation of software and hardware that involves a real-world device. We will discover the behaviour of the system if the software elements of this model are guided by mathematical relationships. For testing conditions that may be difficult to replicate with hardware prototypes alone, modelling and simulation are particularly useful, especially in the early phase of the design process when hardware might not be available. Model-based approach in MATLAB-Simulink can be useful for predictive maintenance of machines as it can reduce unplanned downtimes and maintenance costs when industrial equipment breaks. Through this bibliometric …

Bibliometric Analysis Of Research Trends In Rice Straw/Husk Reinforced Polymer Composites, Deepak D Dr., Abhishek S. Madival, Anupkumar M. Bongale Dr.

Library Philosophy and Practice (e-journal)

Bibliometric research is statistical analysis of publications to identify the most influencing sources of research pertaining to a specific area of research. This paper presents an overview research on rice straw/husk (RS/RH) reinforced polymer composites by using the bibliometric indicators to establish the research framework and to identify the essential research. The relevant journals, authors, institutions and countries which have significantly contributed to research on RS/RH based composite is focused. The bibliometric data is generated through Scopus database. It is observed that the number of publications on characterization of RS/RH based composites are consistently increasing over the last few years …

Electron Microscopy Observation Of Electric Field-Assisted Sintering Of Stainless Steel Nanoparticles, Fei Wang, Qin Zhou, Xing-Zhong Li, Yongchul Yoo, Michael Nastasi, Bai Cui

Department of Mechanical and Materials Engineering: Faculty Publications

The intrinsic role of electrical current on the electric field-assisted sintering (EFAS) process of stainless steel 316L nanoparticles has been revealed by both ex situ and in situ experiments. A novel device on the Si chip has been designed and fabricated to fit into the sample holder of a transmission electron microscope for these experiments. The evolution of nanoparticle morphology and microstructures during the EFAS process has been studied using scanning electron microscopy and transmission electron microscopy, which has been combined with the simultaneous measurement of the electric voltage and current changes. A preliminary four-stage mechanism for the EFAS process …

Biomechanics Of Head Impacts In An Unhelmeted Sport, Stephen Tiernan

Doctoral

Concussion in sport is very common and often the injury is undetectable using CT and MRI scans. In addition, approximately 50% of concussions areunreported.The project initially investigated the suitability of a skin patch sensor and a head-band sensorfor the measurement of head impacts in unhelmeted sports. It was found that both were unsuitable due to large angular accelerationerrors. Thestudy then collaborated withCAMLab at Stanford University and 25 Mixed Martial Arts (MMA) athletes were fitted CAMLab’s validated instrumented mouthguard. 451 video confirmed impacts were recorded at 19 sparring and 11 competitive MMA events. Five concussions were diagnosed during the competitive events. …

A Bibliometric Analysis Of Ultrasonic Vibration Assisted Turning, Govind S. Ghule, Sudarshan Sanap Prof. Dr.

Library Philosophy and Practice (e-journal)

Ultrasonic vibration-assisted turning (UVAT) is a new crossover in machining techniques which uses high frequency, low amplitude sound waves which are further superimposed on the cutting tool in traditional turning. This innovative technology is being utilized over the decades due to its conspicuous influence contrasted with traditional approach particularly in turning of hard-to-machine materials. This present paper analyses the past explores in the arena of ultrasonic vibration-assisted turning, by a far-reaching bibliometric investigation. The analysis is carried out by scrutinizing the studies through Science Direct and Scopus database to select the peer-reviewed papers. The advanced research tools like the word …

Mid-Infrared Laser Absorption Spectroscopy And Ignition Delay Time Measurements Of Advanced Renewable Fuels At High Pressure In A Shock Tube, Erik Ninnemann

Electronic Theses and Dissertations, 2020-2023

The United States government has set 2050 as the target for net-zero greenhouse gas emissions due to their increasing levels and the subsequent rise in global temperatures. To meet this target, there has been renewed interest in the combustion of high-energy biofuels that could combat these issues. Thus, the Department of Energy started the Co-Optimization of Fuels and Engines program to find bioderived blendstocks that can harmonize with current and future generation engines to increase power and efficiency, all while reducing overall emissions. As part of this program, it is crucial to understand the combustion of these fuels at the …

Reclamation Of Fused Silica From Investment Shells Used For Casting Steel, Samuel L. Holt

College of Graduate Studies: Theses & Dissertations

Fused silica is widely used for investment casting shell molds. Fused silica shells are discarded after being used for casting one time. This is due to the transformation of fused silica to beta cristobalite above 1652℉ (900℃). To reduce cost and waste of investment casting foundries, this study is exploring a method to inhibit transformation of fused silica and reclaim it from high temperature investment casting shells. This research has employed firing to minimalize fused silica transformation to cristobalite. The phase transformation is minimalized due to sintering and coarsening of the particles during firing. Coarsening reduces surface area to volume …

Understanding Forearm Muscle Coordination In Children, Miguel Gonzalez

Electronic Theses and Dissertations, 2020-2023

A combination of surface electromyography (EMG) and pattern recognition algorithms have led to improvements in the functionality of upper limb prosthetics. This method of control relies on user's ability to repeatedly generate consistent muscle contractions. Research in EMG based control of prosthesis has mainly utilized adult subjects who have fully developed neuromuscular control. Little is known about children's ability to generate consistent EMG signals necessary to control artificial limbs with multiple degrees of freedom. To address this gap, two experiments were designed to validate and benchmark an experimental protocol that quantifies the ability to coordinate forearm muscle contractions in able-bodied …

The Critical Role Of Dynamic Surface Tension Of Surfactants On The Impact Dynamics Of Water Droplets, Amir Esmaeili, Reza Mohammadi

Graduate Research Posters

Due to their time-dependent surface tension, the addition of surface-active agents or surfactants to water for specific applications has made controlling the impact dynamics of these droplets a complex phenomenon. This work investigates the influence of the molecular weight, concentration, and ionic nature of the surfactants as well as the substrate surface characteristics on the impact dynamics of surfactant-laden droplets using a high-speed camera at 10000 frames per second. Sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, and n-decanoyl-n-methylglucamine were used as anionic, cationic, and nonionic surfactants, respectively. We used hydrophilic glass slides, hydrophobic polytetrafluoroethylene, and superhydrophobic alkyl ketene dimer (AKD) as substrates. …

Design Of A Heat Exchanger For A Supercritical Co2 Turbine System, Kehinde Oluwatobi Adenuga

Graduate Theses, Dissertations, and Problem Reports (ETD)

This research aims at designing a shell and tube heat exchanger which will drive a turbine operated on supercritical CO₂. Hot gases from boiler (simulated using air) at 1500 K is introduced into the shell to heat up the supercritical CO₂ at 10 MPa flowing within tubes from 450 K to 1050 K. The design was done using selected shell and tube heat exchanger empirical equations at predefined boundary conditions. The effect of shell and tube diameter on other design parameters was examined. It was observed that the number of tubes, tube external and internal side surface …

Electroosmotic Flow Of Viscoelastic Fluid Through A Constriction Microchannel, Jianyu Ji, Shizhi Qian, Zhaohui Liu

Mechanical & Aerospace Engineering Faculty Publications

Electroosmotic flow (EOF) has been widely used in various biochemical microfluidic applications, many of which use viscoelastic non-Newtonian fluid. This study numerically investigates the EOF of viscoelastic fluid through a 10:1 constriction microfluidic channel connecting two reservoirs on either side. The flow is modelled by the Oldroyd-B (OB) model coupled with the Poisson–Boltzmann model. EOF of polyacrylamide (PAA) solution is studied as a function of the PAA concentration and the applied electric field. In contrast to steady EOF of Newtonian fluid, the EOF of PAA solution becomes unstable when the applied electric field (PAA concentration) exceeds a critical value for …

Simulation Of Particle Transport In A Multi-Component Flow With A High Viscosity Ratio Driven By Slender Structures, Michael Roeing-Donna

Graduate Research Theses & Dissertations

Simulating particle transport in multi-component fluid flows driven by slender structures is important but challenging, especially when dealing with large viscosity ratios. In this thesis, a general multi-physics model is introduced to handle multi-component fluid flows, slender beating structures, immersed particles/droplets, and their interactions. This multi-physics model has been validated with analytical solutions and other published experimental and numerical results for the mean mucous velocity. The validated model is used to study particle transport in nasal mucous layer, the interplay between cilia and fluid flow. The model shows that mucous-pericilairy layer interface and mucous-air interface remain a constant height throughout …

Modeling Study Of Electrocoagulation System For Treating Wastewater, Swachwa Dey

Graduate Research Theses & Dissertations

Effective treatment of wastewater from households, communities, and industries is vital to preserve our environment. Chemical treatment to add coagulants into the wastewater is the most popular treatment method, but due to the high operating cost and secondary contamination issue, a novel method to solve those issues is required. In this study, we revisited the electro-coagulation (EC) system which has promising features of low system/operating cost and environment friendly process. EC was actively developed once, but due to the low efficiency and scaling-up issues, it could not be fully utilized. In this study, physics-based mathematical model was developed to elucidate …