Mechanical Engineering Commons^™

Water Transport Through Porous Media And In Flow Channels Of Proton Exchange Membrane Fuel Cell, Mehdi Mortazavi

Dissertations, Master's Theses and Master's Reports - Open

Proton exchange membrane (PEM) fuel cell has been known as a promising power source for different applications such as automotive, residential and stationary. During the operation of a PEM fuel cell, hydrogen is oxidized in anode and oxygen is reduced in the cathode to produce the intended power. Water and heat are inevitable byproducts of these reactions. The water produced in the cathode should be properly removed from inside the cell. Otherwise, it may block the path of reactants passing through the gas channels and/or gas diffusion layer (GDL). This deteriorates the performance of the cell and eventually can cease …

Hybrid Tio2 Solar Cells Produced From Aerosolized Nanoparticles Of Water-Soluble Polythiophene Electron Donor Layer, Marshall L. Sweet, Joshua G. Clarke, Dmitry Pestov, Gary C. Tepper, James T. Mcleskey Jr.

Mechanical and Nuclear Engineering Publications

Hybrid solar cells (HSCs) with water soluble polythiophene sodium poly[2-(3-thienyl)-ethyloxy-4-butylsulfonate] (PTEBS) thin films produced using electrospray deposition (ESD) were fabricated, tested, and modeled and compared to devices produced using conventional spin coating. A single device structure of FTO/TiO2/PTEBS/Au was used to study the effects of ESD of the PTEBS layer on device performance. ESD was found to increase the short circuit current density (J_sc) by a factor of 2 while decreasing the open circuit voltage (V_oc) by half compared to spin coated PTEBS films. Comparable efficiencies of 0.009% were achieved from both device construction types. Current-voltage …

Development Of Chatter Attenuation Robust Control For An Amb Machine Spindle, Alexander Hans Pesch

ETD Archive

No abstract provided.

Development Of Test Methodology For Evaluation Of Fuel Economy In Motorcycle Engines, Alexander Michlberger

ETD Archive

Rising fuel costs and concerns over fossil fuel emissions have resulted in more stringent fuel economy and emissions standards globally. As a result, motor vehicle manufacturers are constantly pushed to develop more efficient engine and drivetrain systems. Along with advances in hardware, the development of highly fuel efficient engine oils and driveline lubricants can have a significant impact on total system efficiency. Recently motorcycle fuel economy and emissions have come under increased scrutiny. While the passenger vehicle and heavy duty vehicle industries employ a variety of American Society for Testing and Materials (ASTM) standardized tests to measure fuel economy and …

Variable Speed Flapping Wing Micro Air Vehicle Using A Continuous Variable Transmission Design, Jason C. Chuang

Browse all Theses and Dissertations

Flapping wing micro air vehicles (FWMAV) have very unique flight mechanics in two-wing orientation. Many challenges arise with two wing configuration: lift production, design construction, and control systems. Control surfaces used in fixed wings can be used but at low Reynolds numbers they become less effective. In order to truly mimic insects with two wings, control mechanisms must be developed. Since MAVs are designed to navigate through confined spaces they need to have many degrees of freedom in motion. One way is to use a continuous variable transmission (CVT) mechanism, by integrating its infinite gear ratios to change the flapping …

Me-Em 2013-14 Annual Report, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering Annual Reports

Table of Contents

• Human-Centered Engineering
• Enrollment & Degrees
• Graduates
• Faculty & Staff
• Alumni
• Donors
• Contracts & Grants
• Patents & Publications

Bike Braking Vibration Modelling And Measurement, Rob Redfield

United States Air Force: Publications

Modern bicycle disk-brake systems often induce vibration and noise in bike components such as brake rotors, wheels, and even bike frames. When the vibration or noise are excessive, brake performance can be perceived as unsatisfactory. Previous research incorporating bike frame structural dynamics and brake friction modeling has shown that stick-slip friction is likely the cause of much of this vibration and noise. Bicycle design parameters such as brake friction behavior and bike component structural properties are central in producing and/or sustaining these vibrations. The predicted dynamics of these models has correlated reasonably well with the testing of braking systems. This …

Heavy Element Doping For Enhancing Thermoelectric Properties Of Nanostructured Zinc Oxide, Priyanka Jood, Rutvik J. Mehta, Yanliang Zhang, Theo Borca-Tasciuc, Shi Xue Dou, David J. Singh, Ganpati Ramanath

Mechanical and Biomedical Engineering Faculty Publications and Presentations

ZnO is a high melting point, high charge carrier mobility semiconductor with potential as a thermoelectric material, but its high thermal conductivity κ is the limiting factor for increasing the thermoelectric figure of merit ZT. Here, we demonstrate that doping ZnO with heavy elements can significantly enhance ZT. Indium doping leads to ultralow κ 3 W m⁻¹ K⁻¹ and a high power factor α²σ 1.230 × 10⁻³ W m⁻¹ K⁻², yielding ZT_1000K 0.45 that is 80% higher than non-nanostructured In–Zn–O alloys. Although Bi doping also yields a high Seebeck coefficient of …

High-Efficiency Thrust Vector Control Allocation, Jeb S. Orr, Nathan Slegers

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

A generalized approach to the allocation of redundant thrust vector slew commands for multi-actuated launch vehicles is presented, where deflection constraints are expressed as omniaxial or elliptical deflection limits in gimbal axes. More importantly than in the aircraft control allocation problem, linear allocators (pseudoinverses) are preferred for large booster applications to facilitate accurate prediction of the control-structure interaction resulting from thrust vectoring effects. However, strictly linear transformations for the allocation of redundant controls cannot, in general, access all of the attainable moments for which there is a set of control effector positions thatsatisfles the constraints. In this paper, the control …

Gust Mitigation Of Micro Air Vehicles Using Passive Articulated Wings, Adetunji Oduyela, Nathan Slegers

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Birds and insects naturally use passive flexing of their wings to augment their stability in uncertain aerodynamic environments. In a similar manner, micro air vehicle designers have been investigating using wing articulation to take advantage of this phenomenon. The result is a class of articulated micro air vehicles where artificial passive joints are designed into the lifting surfaces. In order to analyze how passive articulation affects performance of micro air vehicles in gusty environments, an efficient 8 degree-of-freedom model is developed. Experimental validation of the proposed mathematical model was accomplished using flight test data of an articulated micro air vehicle …

Modeling Of Transfer Path For Determination Of Combustion And Noise Metrics On Diesel Engines, Libin Jia

Dissertations, Master's Theses and Master's Reports - Open

Determination of combustion metrics for a diesel engine has the potential of providing feedback for closed-loop combustion phasing control to meet current and upcoming emission and fuel consumption regulations. This thesis focused on the estimation of combustion metrics including start of combustion (SOC), crank angle location of 50% cumulative heat release (CA50), peak pressure crank angle location (PPCL), and peak pressure amplitude (PPA), peak apparent heat release rate crank angle location (PACL), mean absolute pressure error (MAPE), and peak apparent heat release rate amplitude (PAA). In-cylinder pressure has been used in the laboratory as the primary mechanism for characterization of …

Analysis Of A Chemical Model System Leading To Chiral Symmetry Breaking: Implications For The Evolution Of Homochirality, Brandy N. Morneau, Jaclyn M. Kubala, Carl Barratt, Pauline Schwartz

Chemistry and Chemical Engineering Faculty Publications

Explaining the evolution of a predominantly homochiral environment on the early Earth remains an outstanding challenge in chemistry. We explore here the mathematical features of a simple chemical model system that simulates chiral symmetry breaking and amplification towards homochirality. The model simulates the reaction of a prochiral molecule to yield enantiomers via interaction with an achiral surface. Kinetically, the reactions and rate constants are chosen so as to treat the two enantiomeric forms symmetrically. The system, however, incorporates a mechanism whereby a random event might trigger chiral symmetry breaking and the formation of a dominant enantiomer; the non-linear dynamics of …

Optimal Dredge Fleet Scheduling Within Environmental Work Windows, Heather Nachtmann, Kenneth N. Mitchell, Chase Rainwater, Ridvan Gedik, Edward A. Pohl

Mechanical and Industrial Engineering Faculty Publications

The U. S. Army Corps of Engineers oversees dredging in hundreds of navigation projects annually, through its fleet of government equipment and through individual contracts with private industry. The research presented here sought to examine the decision to allocate dredge resources to projects systemwide under necessary constraints. These constraints included environmental restrictions on when dredging could take place in response to the migration patterns of turtles, birds, fish, and other wildlife; dredge equipment resource availability; and varying equipment productivity rates that affected project completion times. The paper discusses problem definition and model formulation of optimal dredge fleet scheduling within environmental …

Design And Evaluation Of A Propulsion System For Small, Compact, Low-Speed Maneuvering Underwater Vehicles, Florence M. Mbithi

Electronic Theses and Dissertations

Underwater vehicles used to perform precision inspection and non-destructive evaluation in tightly constrained or delicate underwater environments must be small, have low-speed maneuverability and a smooth streamlined outer shape with no appendages. In this thesis, the design and analysis of a new propulsion system for such underwater vehicles is presented. It consists primarily of a syringe and a plunger driven by a linear actuator and uses different inflow and outflow nozzles to provide continuous propulsive force. A prototype of the proposed propulsion mechanism is built and tested. The practical utility and potential efficacy of the system is demonstrated and assessed …

Computational Fluid Dynamics Uncertainty Analysis For Payload Fairing Spacecraft Environmental Control Systems, Curtis Groves

Electronic Theses and Dissertations

Spacecraft thermal protection systems are at risk of being damaged due to airflow produced from Environmental Control Systems. There are inherent uncertainties and errors associated with using Computational Fluid Dynamics to predict the airflow field around a spacecraft from the Environmental Control System. This paper describes an approach to quantify the uncertainty in using Computational Fluid Dynamics to predict airflow speeds around an encapsulated spacecraft without the use of test data. Quantifying the uncertainty in analytical predictions is imperative to the success of any simulation-based product. The method could provide an alternative to traditional “validation by test only” mentality. This …

Numerical Investigation Of Boiling In A Sealed Tank In Microgravity, Sonya Lynn Hylton

ETD Archive

NASA's missions in space depend on the storage of cryogenic fluids for fuel and for life support. During long-term storage, heat can leak into the cryogenic fluid tanks. Heat leaks can cause evaporation of the liquid, which pressurizes the tank. However, when the tanks are in a microgravity environment, with reduced natural convection, heat leaks can also create superheated regions in the liquid. This may lead to boiling, resulting in much greater pressure rises than evaporation at the interface between the liquid and vapor phases. Models for predicting the pressure rise are needed to aid in developing methods to control …

Quality And Safety Of Minimally Invasive Surgery: Past, Present, And Future, Bernadette Mccrory, Chad A. Lagrange, M. S. Hallbeck

Department of Mechanical and Materials Engineering: Faculty Publications

Adverse events because of medical errors are a leading cause of death in the United States (US) exceeding the mortality rates of motor vehicle accidents, breast cancer, and AIDS. Improvements can and should be made to reduce the rates of preventable surgical errors because they account for nearly half of all adverse events within hospitals. Although minimally invasive surgery (MIS) has proven patient benefits such as reduced postoperative pain and hospital stay, its operative environment imposes substantial physical and cognitive strain on the surgeon increasing the risk of error. To mitigate errors and protect patients, a multidisciplinary approach is needed …

Measurement Of Hydrodynamic Force Generation By Swimming Dolphins Using Bubble Dpiv, Frank E. Fish, Paul Legac, Terrie M. Williams, Timothy Wei

Department of Mechanical and Materials Engineering: Faculty Publications

Attempts to measure the propulsive forces produced by swimming dolphins have been limited. Previous uses of computational hydrodynamic models and gliding experiments have provided estimates of thrust production by dolphins, but these were indirect tests that relied on various assumptions. The thrust produced by two actively swimming bottlenose dolphins (Tursiops truncatus) was directly measured using digital particle image velocimetry (DPIV). For dolphins swimming in a large outdoor pool, the DPIV method used illuminated microbubbles that were generated in a narrow sheet from a finely porous hose and a compressed air source. The movement of the bubbles was tracked …

An Assessment Of Flow Regime Maps And A Numerical Heat Transfer Correlation For The Stratified/Annular Regime Of Shear-Driven Internal Condensing Flows, Fnu Nikhil Shankar

Dissertations, Master's Theses and Master's Reports - Open

Several modern-day cooling applications require the incorporation of mini/micro-channel shear-driven flow condensers. There are several design challenges that need to be overcome in order to meet those requirements.

The difficulty in developing effective design tools for shear-driven flow condensers is exacerbated due to the lack of a bridge between the physics-based modelling of condensing flows and the current, popular approach based on semi-empirical heat transfer correlations. One of the primary contributors of this disconnect is a lack of understanding caused by the fact that typical heat transfer correlations eliminate the dependence of the heat transfer coefficient on the method of …

An Investigation Of Variable Valve Timing Effects On Hcci Engine Performance, Hrishikesh Abhay Saigaonkar

Dissertations, Master's Theses and Master's Reports - Open

The Homogeneous Charge Compression Ignition (HCCI) engine is a promising combustion concept for reducing NO_x and particulate matter (PM) emissions and providing a high thermal efficiency in internal combustion engines. This concept though has limitations in the areas of combustion control and achieving stable combustion at high loads. For HCCI to be a viable option for on-road vehicles, further understanding of its combustion phenomenon and its control are essential. Thus, this thesis has a focus on both the experimental setup of an HCCI engine at Michigan Technological University (MTU) and also developing a physical numerical simulation model called the …