Engineering Commons^™

Radiation Force Modeling For A Wave Energy Converter Array, Salman Husain, Gordon Parker, David Forehand, Enrico Anderlini

Michigan Tech Publications, Part 2

The motivation and focus of this work is to generate passive transfer function matrices that model the radiation forces for an array of WECs. Multivariable control design is often based on linear time-invariant (LTI) systems such as state-space or transfer function matrix models. The intended use is for designing real-time control strategies where knowledge of the model’s poles and zeros is helpful. This work presents a passivity-based approach to estimate radiation force transfer functions that accurately replace the convolution operation in the Cummins equation while preserving the physical properties of the radiation function. A two-stage numerical optimization approach is used, …

Biogas Combustion Characteristics In A Concentric Flow Slot Burner: Effects Of Co2 Concentration On Stability And Flame Structure, Maged Kiriakos

Theses and Dissertations

Biogas combustion is affected by the concentration of carbon dioxide. The successful applications of Biogas as a sustainable renewable alternative fuel produced from waste depend on its combustion stability, heat release, and pollution level. The aim of the current study is to apply new combustion technology and study the stability and combustion characteristics of natural gas with different percentages of carbon dioxide from 0 to 40% simulating biogas fuel. The stability characteristics and the temperature profiles of turbulent planar flames at different levels mixture inhomogeneity are investigated and presented in this work. The flames are created in a newly developed …

Linearized Rigid-Body Static And Dynamic Stability Of An Aircraft With A Bio-Inspired Rotating Empennage, Austin J. Kohler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The United States Air Force (USAF) will likely seek to remove the vertical tail of next-generation fighter aircraft. This work seeks to characterize the static and dynamic stability and handling qualities of a vertical-tailless aircraft concept that would satisfy the USAF’s goal. This concept aircraft, one modified with a Bio-Inspired Rotating Empennage (BIRE), does not have a vertical tail, and is instead capable of rotating the horizontal tail about the fuselage axis for maneuvering. The dynamic characteristics of the BIRE-modified aircraft are compared to a baseline unmodified aircraft, similar to the F16, with a traditional vertical tail. Linearized aerodynamic models …

Assessment Of Stability Of The Body Elements Of A Dynamometric Car For Special Technical Purpose, F F. Khikmatov, Y O. Ruzmetov

Technical science and innovation

In the work, studies were carried out to assess the stability of the body elements of a dynamometric car for special technical purposes for the railways of the Republic of Uzbekistan. Distinctive features of the proposed design of the dynamometric car from the car of the analogue model 61-907 are considered. The results of theoretical calculations for the stability of the body elements of the developed design of a dynamometric car in three design modes are given: under compression, tension and impact.

Fabrication Of Asymmetrical Hollow Fiber-Supported Thin Film Membranes, Stack Assembly, And Accelerated Long-Term Stability Test For Oxygen Production From Air, Myongjin Lee

Theses and Dissertations

Air separation is a widely used process for oxygen production. Several separation technologies have been developed for air separation, including cryogenic distillation, swing adsorption, redox process of metal oxides, and electrochemical process. Among these technologies, electrochemical permeation process stands out as a cost-effective and simple process for pure oxygen production from air. The electrochemical permeation process employs a gas-tight membrane to permeate and separate oxygen from air directly, where the membrane conducts both ions and electrons simultaneously. Different membrane designs have been studied to obtain the improved performance for oxygen permeation, typically planar and tubular designs. Among these membrane configurations, …

Developing New Crutch Tip Design For Overall Increased Stability And Improved Movement On Different Terrains, Lauren Skinner

Honors Theses

Crutches are a mobility assistive device that are often used in various situations, such as post- surgical rehabilitation and recovery after injury. The current crutch tip design that is used on today’s crutches are often unstable and do not provide quality movement on different terrains, such as snow, ice, mud, and wet surfaces. These problems would be solved with a new tip design that could be attached to existing crutches or manufactured with the crutch itself. The team’s solution to this problem is a crutch tip with modular parts. The tip would attach to the shaft of the crutch like …

A Review Of Avian-Inspired Morphing For Uav Flight Control, Christina Harvey, Lawren L. Gamble, Christian R. Bolander, Douglas F. Hunsaker, James J. Joo, Daniel J. Inman

Mechanical and Aerospace Engineering Faculty Publications

The impressive maneuverability demonstrated by birds has so far eluded comparably sized uncrewed aerial vehicles (UAVs). Modern studies have shown that birds’ ability to change the shape of their wings and tail in flight, known as morphing, allows birds to actively control their longitudinal and lateral flight characteristics. These advances in our understanding of avian flight paired with advances in UAV manufacturing capabilities and applications has, in part, led to a growing field of researchers studying and developing avian-inspired morphing aircraft. Because avian-inspired morphing bridges at least two distinct fields (biology and engineering), it becomes challenging to compare and contrast …

Investigation Of Control Parameters, Strategies, And Transport Modeling For Effective Electrokinetic Nanoparticle Treatment Of Cementitious Materials, Huayuan Zhong

Doctoral Dissertations

Various deleterious chemical species (including sulfates, chlorides, and others) contaminate concrete structures which are inherently porous and thus suffer from compromised durability. Several technologies have been developed for repairing concrete or enhancing the service life. Nevertheless, their efficiency, practicability, and cost can vary widely. Compared with chemical grout, fiber wrap, and traditional repair technology, electrokinetic nanoparticle treatment (EN) has been found to provide remarkable benefits for strength restoration and mitigation of durability problems via porosity reduction. Nanoparticle instability and over dosage issues can arise and lead to problems during treatments. In many cases, these treatment processes have been accompanied by …

Digital Cutting Force Modeling For Milling Operations, Timothy T. No

Doctoral Dissertations

Process improvement in milling through improved understanding of machining dynamics is an on-going research endeavor. The objective of this project is to advance digital modeling of the milling process by incorporating tool-specific geometry in the machining analysis. Structured light scanning will be used to perform tool geometry measurements and produce a 3D model. The 3D model data will include the spatial location of the cutting edges, as well as the rake and relief profiles from the tool cross section. The rake and relief profiles will be imported, together with the work material flow stress model, into a finite element analysis …

Vibration Behavior In Modulated Tool Path (Mtp) Turning, Ryan William Copenhaver

Doctoral Dissertations

This project studies the process dynamics and surface finish effects of modulated tool path (MTP) turning. In MTP turning, a small amplitude (typically less than 0.5 mm), low frequency oscillation (typically less than 10 Hz) is superimposed on the feed motion by the machine controller to intentionally segment the traditionally long, continuous chips. The basic science to be examined is the vibration behavior of this special case of interrupted cutting, which is not turning because the chip formation is intentionally discontinuous and is not milling because the time-dependent chip geometry is defined by the oscillatory feed motion, not the trochoidal …

Derivation And Exploration Of Analytical Aircraft Stability Analysis, Roderick Landreth

Honors Theses

A comprehensive measure of the in-flight stability of an aircraft is essential, though it can take a large amount of resources to do accurately and usefully. Small companies and colleges often don't have the resources to attain accurate experimental or analytical data to describe stable flight before potential failure. This composition investigates methods of completing a static and dynamic stability analysis for an aircraft feasible for a college, small business or hobbyist to complete, with the goal to eliminate the 'barrier of entry' concerning a lack of information and resources. A sample analytical calculation for static stability of Union College's …

Enabling Compact Devices Through Origami And Developable Mechanisms, Jacob Ryan Greenwood

Theses and Dissertations

This thesis provides resources that enable the design of novel and compact mechanical devices by providing terminology, engineering models, and design methods in the fields of developable mechanisms and origami-based engineering.The first part of this work presents engineering models to aid in the design of cylindrical developable mechanisms. These models take into account the added spatial restrictions imposed by the developable surface. Equations are provided for the kinematic analysis of cylindrical developable mechanisms. A new classification for developable mechanisms is also presented (intramobile, extramobile, and transmobile) and two graphical methods are provided for determining this classification for single-DOF planar cylindrical …

Origami-Based Design Of Fold States And Stability, Alex Avila

Theses and Dissertations

Origami is a potentially elegant and powerful source of inspiration for many engineering designs. The viable shapes (fold states) of a single device allow it to perform multiple, seemingly contradictory, functions. The fold state is a large factor in the device's performance, but there are challenges in selecting and maintaining those fold states. In this thesis we analyze existing concepts for overcoming these challenges. Those concepts are compared with those that occur in origami-based devices. From this analysis fundamental gaps were identified, specifically, shortcoming in the terminology used to refer to (1) non-flat origami states and (2) sets of facets …

Strong Stability Of A Class Of Difference Equations Of Continuous Time And Structured Singular Value Problem, Qian Ma, Keqin Gu, Narges Choubedar

SIUE Faculty Research, Scholarship, and Creative Activity

This article studies the strong stability of scalar difference equations of continuous time in which the delays are sums of a number of independent parameters tau_i, i = 1, 2, . . . ,K. The characteristic quasipolynomial of such an equation is a multilinear function of exp(-tau_i s). It is known that the characteristic quasipolynomial of any difference equation set in the form of one-delayper- scalar-channel (ODPSC) model is also in such a multilinear form. However, it is shown in this article that some multilinear forms of quasipolynomials are not characteristic quasipolynomials of any ODPSC difference equation set. The equivalence …

Strong Stability Of A Class Of Difference Equations Of Continuous Time And Structured Singular Value Problem, Qian Ma, Keqin Gu, Narges Choubedar

SIUE Faculty Research, Scholarship, and Creative Activity

This article studies the strong stability of scalar difference equations of continuous time in which the delays are sums of a number of independent parameters τi, i = 1, 2, . . . , K. The characteristic quasipolynomial of such an equation is a multilinear function of e−τis. It is known that the characteristic quasipolynomial of any difference equation set in the form of one-delay-per-scalar-channel (ODPSC) model is also in such a multilinear form. However, it is shown in this article that some multilinear forms of quasipolynomials are not characteristic quasipolynomials of any ODPSC difference equation set. The equivalence between …

Effect Of Moment Gradient And Load Height With Respect To Centroid On The Reliability Of Wide Flange Steel Beams Subject To Elastic Lateral Torsional Buckling, Christopher D. Eamon, Alexander W. Lamb, Kapil Patki

Civil and Environmental Engineering Faculty Research Publications

The reliability of doubly-symmetric wide flange steel beams designed to the AISC Specification for Structural Steel Buildings subjected to elastic lateral torsional buckling was evaluated when considering variation in moment gradient and load height. The analysis considers continuous loads on spans subjected to various end moments with supports that are torsionally fixed and laterally supported, without additional intermediate restraints. Dead load, occupancy live load, and beam resistance random variables were considered. Beam lateral torsional buckling resistance was evaluated from numerical solution of a fundamental differential equation that accounts for the effect of moment gradient and load height. In some cases, …

Novel Nanomaterials For Lithium Ion Batteries And Oxygen Reduction Reactions, Jianyang Li

Theses and Dissertations

Undoubtedly, one of the most pressing issues that world is dealing with today is global warming. It requires long-term potential actions for sustainable development to achieve solutions to address this kind of environmental problems that we are facing today. In this regard, renewable energy resources appear to be the one of the most efficient and effective solutions to reduce reliance on fossil fuels that cause release of excess amounts of carbon dioxide, the main contributor to global warming. As an alternative, electrochemical energy production has long been explored due to its intrinsic nature of more sustainable and more environmentally friendly. …

Wrinkling Of Functionally Graded Sandwich Structures Subject To Biaxial And In-Plane Shear Loads, Harold Costa

Masters Theses

"Benefits of a functionally graded core increasing wrinkling stability of sandwich panels have been demonstrated in a recent paper [1] where a several-fold increase in the wrinkling stress was observed, without a significant weight penalty, using a stiffer core adjacent to the facings. In the present paper wrinkling is analyzed in case where the facings are subject to biaxial compression and/or in-plane shear loading and the core is arbitrary graded through-the-thickness. Two issues addressed are the effect of biaxial or in-plane shear loads on wrinkling stability of panels with both graded and ungraded core and the verification that functional grading …

Intelligent Control Of A Class Of Nonlinear Systems, Phuong D. Ngo

Open Access Dissertations

The objective of this study is to improve and propose new fuzzy control algorithms for a class of nonlinear systems. In order to achieve the objectives, novel stability theorems as well as modeling techniques are also investigated. Fuzzy controllers in this work are designed based on the fuzzy basis function neural networks and the type-2 Takagi-Sugeno fuzzy models.

For a class of single-input single-output nonlinear systems, a new stability condition is derived to facilitate the design process of proportional-integral Mamdani fuzzy controllers. The stability conditions require a new technique to calculate the dynamic gains of nonlinear systems represented by fuzzy …

Modified Trajectory Shaping Guidance For Autonomous Path Following Control Of Platooning Ground Vehicles, Ishmaal T. Erekson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis proposes a modification of trajectory shaping guidance to provide more accurate path convergence in curved paths. The object of this thesis is to apply this simple guidance law to platooning control to ensure all vehicles in the platoon converge to a desired constant radius path at a desired vehicle separation distance. To show the viability of this new guidance law, it is shown mathematically to be exponentially stable. It is also confirmed through simulations and on ground robots.

Low Temperature Solution-Processed Sb:Sno2 Nanocrystals For Efficient Planar Perovskite Solar Cells, Yang Bai, Yanjun Fang, Yehao Deng, Qi Wang, Jingjing Zhao, Xiaopeng Zheng, Yang Zhang, Jinsong Huang

Department of Mechanical and Materials Engineering: Faculty Publications

Inorganic metal oxide electron-transport layers (ETLs) have the potential to yield perovskite solar cells with improved stability, but generally need high temperature to form conductive and defect-less forms, which is not compatible with the fabrication of flexible and tandem solar cells. Here, we demonstrate a facile strategy for developing efficient inorganic ETLs by doping SnO₂ nanocrystals (NCs) with a small amount of Sb using a low-temperature solution-processed method. The electrical conductivity was remarkably enhanced by Sb-doping, which increased the carrier concentration in Sb:SnO₂ NCs. Moreover, the upward shift of the Fermi level owing to doping results in improved …

Co-Design Of Dynamic Real-Time Scheduling And Cooperative Control For Human-Agent Collaboration Systems Based On Mutual Trust, Xiaotian Wang

All Theses

Mutual trust is a key factor in human-human collaboration. Inspired by this social interaction, we analyze human-agent mutual trust in the collaboration of one human and (semi)autonomous multi-agent systems. In the thesis, we derive time-series human-agent mutual trust models based on results from human factors engineering. To avoid both over- trust and under-trust, we set up dynamic timing models for the multi-agent scheduling problem and develop necessary and sufficient conditions to test the schedulability of the human multi-agent collaborative task. Furthermore, we extend the collaboration between one human and multiple agents into the collaboration between multi-human network and swarm-based agents …

The Use Of Initial Imperfection Approach In Design Process And Buckling Failure Evaluation Of Axially Compressed Composite Cylindrical Shells

Faculty of Engineering University of Malaya

Thin-walled cylindrical shells are susceptible to buckling failures caused by the axial compressive loading. During the design process or the buckling failure evaluation of axially-compressed cylindrical shells, initial geometric and loading imperfections are of important parameters for the analyses. Therefore, the engineers/designers are expected to well understand the physical behaviours of shell buckling to prevent unexpected serious failure in structures. In particular, it is widely reported that no efficient guidelines for modelling imperfections in composite structures are available. Knowledge obtained from the relevant works is open for updates and highly sought. In this work, we study the influence of imperfections …

Design Considerations Towards The Construction Of Hybrid Floating Brush Seal (Hfbs), S. Lattime, Minel Braun, Fred Choy

Fred K. Choy

The hybrid floating brush seal (HFBS) represents an advance in brush seal technology by combining brush seal and film riding face seal technologies to create a hybrid seal that allows both axial and radial excursions of the sealed shaft without damage to seal integrity. At the same time, it eliminates interface surface speeds between the rotor and the brush bristles. This accomplishment is possible because the brush seal, which forms the primary seal, rotates with the shaft, while floating against a hydrodynamic face seal surface, which makes up the secondary seal. The present paper presents continuation work (Int J of …

La0.7Sr0.3Fe0.7Ga0.3O3-Δ As Electrode Material For A Symmetrical Solid Oxide Fuel Cell, Zhibin Yang, Yu Chen, Chao Jin, Guoliang Xiao, Minfang Han, Fanglin Chen

Fanglin Chen

In this research, La_0.7Sr_0.3Fe_0.7Ga_0.3O_3−δ (LSFG) perovskite oxide was successfully prepared using a microwave-assisted combustion method, and employed as both anode and cathode in symmetrical solid oxide fuel cells. A maximum power density of 489 mW cm⁻² was achieved at 800 °C with wet H₂ as the fuel and ambient air as the oxidant in a single cell with the configuration LSFG|La_0.8Sr_0.2Ga_0.83Mg_0.17O_3−δ|LSFG. Furthermore, the cells demonstrated good stability in H₂ and acceptable sulfur tolerance.

Characterization Of Sr‐Doped Lamno3 And Lacoo3 As Cathode Materials For A Doped Lagao3 Ceramic Fuel Cell, Kevin Huang, Man Feng, John B. Goodenough, Michael Schmerling

Kevin Huang

Energy dispersive spectrometry line scan and ac impedance spectroscopy were used in this study to investigate the chemical reactions between two cathode materials, La_0.84Sr_0.16MnO₃ (LSM), La_0.5Sr_0.5CoO_3-δ (LSC), and the electrolyte La_0.9Sr_0.1Ga_0.8Mg_0.2O_2.85 (LSGM). Significant interdiffusions of Co into LSGM and Ga into LSC were found at an LSC/LSGM interface even at relatively low fabrication temperatures. In contrast, only small interdiffusions of Mn into LSGM and Ga into LSM were detected at the LSM/LSGM interface even though it was fired at 1470°C. The …

A Reversible And Stable Flake-Like Licoo2 Cathode For Lithium Ion Batteries, Tao Wei, Rui Zeng, Yongming Sun, Yunhui Huang, Kevin Huang

Kevin Huang

A dense and thick flake-like cathode structure was demonstrated to have a preferential crystallographic orientation for Li+ migration and a better tolerance to cracking, both of which enable a reversible and stable capacity at moderate rates from 0.1 to 2 C.

Flux Of Silver-Carbonate Membranes For Post-Combustion Co2 Capture: The Effects Of Membrane Thickness, Gas Concentration And Time, Lingling Zhang, Yunhui Gong, Kyle Brinkman, Tao Wei, Siwei Wang, Kevin Huang

Kevin Huang

No abstract provided.

Surface Modified Silver-Carbonate Mixed Conducting Membranes For High Flux Co2 Separation With Enhanced Stability, Lingling Zhang, Yunhui Gong, Jacob Yaggie, Siwei Wang, Kevin Romito, Kevin Huang

Kevin Huang

No abstract provided.

Impact Of In Situ Physical And Chemical Cleaning On Pvdf Membrane Properties And Performances

Faculty of Engineering University of Malaya

Appropriate selection of cleaning agent is an important factor to achieve a better cleaning efficiency and this topic has become an ongoing discussion. This work assesses the impacts of sodium hydroxide (NaOH) and sodium hypochlorite (NaOCl) aqueous solution towards polyvinylidene fluoride (PVDF) stability at the typical concentrations used in membrane cleaning. The cleaned membranes were characterised using held emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), pure water flux measurement, contact angle, protein retention and tensile testing. Membrane cleaned at elevated temperature and higher concentration presented a higher water flux than the virgin membrane which can be a worrying …