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Articles 17581 - 17610 of 30237

Full-Text Articles in Mechanical Engineering

Development Of Chatter Attenuation Robust Control For An Amb Machine Spindle, Alexander Hans Pesch Jan 2014

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 Jan 2014

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 Jan 2014

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 Jan 2014

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

Department of Mechanical and Aerospace Engineering Annual Reports

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Bike Braking Vibration Modelling And Measurement, Rob Redfield Jan 2014

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 Jan 2014

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 ZT1000K 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 Jan 2014

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 Jan 2014

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 Jan 2014

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 Jan 2014

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 Jan 2014

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 Jan 2014

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 Jan 2014

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 Jan 2014

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 Jan 2014

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 Jan 2014

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 Jan 2014

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 Jan 2014

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 NOx 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 …


Test-Analysis Model Correlation And Calibration Of A Multi-Component Plastic Part, Steven P. Carter Jan 2014

Test-Analysis Model Correlation And Calibration Of A Multi-Component Plastic Part, Steven P. Carter

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

The goal of this project is to learn the necessary steps to create a finite element model, which can accurately predict the dynamic response of a Kohler Engines Heavy Duty Air Cleaner (HDAC). This air cleaner is composed of three glass reinforced plastic components and two air filters. Several uncertainties arose in the finite element (FE) model due to the HDAC’s component material properties and assembly conditions. To help understand and mitigate these uncertainties, analytical and experimental modal models were created concurrently to perform a model correlation and calibration. Over the course of the project simple and practical methods were …


Reconciling Function- And Affordance-Based Design, Benjamin T. Ciavola Jan 2014

Reconciling Function- And Affordance-Based Design, Benjamin T. Ciavola

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

Traditional engineering design methods are based on Simon's (1969) use of the concept function, and as such collectively suffer from both theoretical and practical shortcomings. Researchers in the field of affordance-based design have borrowed from ecological psychology in an attempt to address the blind spots of function-based design, developing alternative ontologies and design processes. This dissertation presents function and affordance theory as both compatible and complimentary. We first present a hybrid approach to design for technology change, followed by a reconciliation and integration of function and affordance ontologies for use in design. We explore the integration of a standard function-based …


Stock Aggregation Model And Virtual Archetype For Large Scale Retrofit Modelling Of Local Authority Housing In Ireland, James Pittam, Paul D. O’Sullivan, Garrett O’Sullivan Jan 2014

Stock Aggregation Model And Virtual Archetype For Large Scale Retrofit Modelling Of Local Authority Housing In Ireland, James Pittam, Paul D. O’Sullivan, Garrett O’Sullivan

Conference Papers

Developing representative archetypes using a bottom up approach for stock modelling is an excellent tool for evaluating the overall performance of the building stock; however it requires detailed analysis of the various building types. Currently there is no detailed housing data base for Local Authority housing in Cork City, Ireland that catalogues the housing stocks geometric properties and thermal characteristics for each typology. This study details a methodology to catalogue the LAH stock and build a detailed housing data base. The GIS web based mapping application Google Street View is used to identify 20 house typologies across 36 LAH developments; …


Thermal Conduction And Heat Generation Phenomena In Li-Ion Cells, Stephen Drake Jan 2014

Thermal Conduction And Heat Generation Phenomena In Li-Ion Cells, Stephen Drake

Mechanical and Aerospace Engineering Dissertations - Archive

Cylindrical lithium ion (Li-ion) cells have demonstrated high power density and energy capacity among other energy storage devices. Despite their already widespread use, the thermal transport properties of cylindrical Li-ion batteries are not well documented and understood, while a sizable amount of work has been carried out for electrical, electrochemical, and materials optimization of Li-ion cells. These thermal phenomena are particularly important for high discharge rate batteries. With this uncertainty, if thermophysical properties are not accounted for in thermal models, the result may be a significant under-prediction or over-prediction of the temperature field in a Li-ion cell.Experimental techniques are described …


Unsteady Thrust Measurement Techniques For Pulse Detonation Engines, Dibesh Dhoj Joshi Jan 2014

Unsteady Thrust Measurement Techniques For Pulse Detonation Engines, Dibesh Dhoj Joshi

Mechanical and Aerospace Engineering Dissertations - Archive

Thrust is a critical performance parameter and its correct determination is necessary to characterize an engine. Many conventional thrust measurement techniques prevail. However, further developments are required for correct measurement of thrust in the case of a pulse detonation engine (PDE), since the entire thrust generation process is intermittent. The significant effect of system dynamics in the form of inertial forces, stress wave propagation and reflections initiated in the structure due to detonations and pulse-to-pulse interaction in a fast operating PDE further complicate the thrust measurement process. These complications call for a further, detailed study of the unsteady thrust characteristics. …


Experimental Investigation Of Nucleate Boiling And Thin-Film Evaporation On Enhanced Silicon Surfaces, Shailesh Malla Jan 2014

Experimental Investigation Of Nucleate Boiling And Thin-Film Evaporation On Enhanced Silicon Surfaces, Shailesh Malla

Mechanical and Aerospace Engineering Dissertations - Archive

The present work consists of two major studies. The first study investigates the effects of surface energy or wettability on nucleate pool boiling and the second study investigates the thin-film evaporative cooling for near junction thermal management. For the first study, effects of surface energy or wettability on critical heat flux (CHF) and boiling heat transfer (BHT) of smooth heated surfaces was studied in saturated pool boiling of water at 1 atm. For this purpose hydrophilic and hydrophobic surfaces were created on one side of 1cm x 1cm double-side polished silicon substrates. A resistive heating layer was applied on the …


Degradation Mechanics Of Bone And Bone Like Materials Via Multiscale Analysis, Md Farzad Sarker Jan 2014

Degradation Mechanics Of Bone And Bone Like Materials Via Multiscale Analysis, Md Farzad Sarker

Mechanical and Aerospace Engineering Dissertations - Archive

Bone fracture is a common health risk for older people suffering from bone disease like osteoporosis. The more severe the osteoporosis is the more structural degradation in bones occurs, which eventually makes bones more fracture prone. The mechanical behavior of bone depends on the structural response of bone constituents over a broad range of length scales spanning from the nanoscale collagen fibril level to the macroscale trabeculae level. As such, in order to understand bone fracture, it is important to know the structure-property relations of bone material over the entire length of scale. Surprisingly, a quantitative understanding of bone fracture …


Wind Field Estimation And Its Utilization In Trajectory And Input Prediction, Jane-Wit Kampoon Jan 2014

Wind Field Estimation And Its Utilization In Trajectory And Input Prediction, Jane-Wit Kampoon

Mechanical and Aerospace Engineering Dissertations - Archive

This dissertation work develops a method for onboard estimation of wind field with spatial and temporal variation based on local wind vector estimation and/or measurements from multiple aircraft flying in the same airspace. Aircraft flying in the same airspace of operation are considered airborne wind sensors scattered over the airspace because of the fact that aircraft carry along with them wind information inherent in their dynamics and kinematics. The onboard wind field estimation is formulated in the framework of parameter estimation based on various wind field models, which are different function of position and time. The online wind field estimation …


Electrowetting On Dielectric Digital Microfluidics For 3-Dimensional Cell Culture And Chemical Screening, Subin Mac George Jan 2014

Electrowetting On Dielectric Digital Microfluidics For 3-Dimensional Cell Culture And Chemical Screening, Subin Mac George

Mechanical and Aerospace Engineering Dissertations - Archive

Microfluidic devices have allowed improved cell culture studies to be carried out by allowing greater spatiotemporal control over the cell environment while at the same time providing greater throughput, increased automation capabilities and reagent savings. To improve the relevancy of such studies, 3-dimensional (3D) cell culture has been attempted in microfluidic devices. 3D cell culture is known to better mimic and recreate the environment that cells in the body experience as compared to conventional 2-dimensional cell culture. However, incorporating 3D cell culture into conventional channel based microfluidic devices have proven to be challenging. Hydrogels which provide the 3D environment in …


Modeling, Estimation, And Analysis Of Unresolved Space Object Tracking And Identification, Laura Suarez Henderson Jan 2014

Modeling, Estimation, And Analysis Of Unresolved Space Object Tracking And Identification, Laura Suarez Henderson

Mechanical and Aerospace Engineering Dissertations - Archive

The problem of orbit determination along with shape determination is significant. The orbit determination problem has been tackled for centuries by some of the greatest mathematicians and physicists. The issue of shape determination of space objects, although more recent, has also been addressed quite extensively. Nevertheless, these problems remain of great interest in the scientific and engineering community, and are addressed in this work. The greatest motivation for the tracking and identification of Earth orbiting objects is the ever-increasing population of space assets and man-made debris. It is of interest to implement new and better techniques to track and identify …


Investigation Of Wetting States On Microstructures After Liquid Drops Contact Groove Base, Mingming Xiang Jan 2014

Investigation Of Wetting States On Microstructures After Liquid Drops Contact Groove Base, Mingming Xiang

Mechanical and Aerospace Engineering Dissertations - Archive

Wetting properties of roughness surfaces have attracted a considerable attention because of both the scientific insight and the practical applications. One of the most intriguing topics of wetting is the so-called Cassie-Baxter and Wenzel transition. Recently, theoretical and experimental works have been done to explore this transition on microstructure-formed surfaces. One of the criteria that most commonly used to judge such transition is whether a liquid drop contacts the base of a roughness groove. It is expected that, after the contact, liquid immediately fills the roughness groove, and subsequently the wetting state is changed from Cassie-Baxter state to that of …


Thermal Design Of Lithium Bromide-Water Solution Vapour Absorption Cooling System For Indirect Evaporative Cooling For It Pod, Digvijay Ramkrishna Sawant Jan 2014

Thermal Design Of Lithium Bromide-Water Solution Vapour Absorption Cooling System For Indirect Evaporative Cooling For It Pod, Digvijay Ramkrishna Sawant

Mechanical and Aerospace Engineering Theses - Archive

Supervising Professor: Dereje Agonafer Nowadays with increase use of internet, mobile there is increase in heat which ultimately increases the efficient cooling system of server room or IT POD. Use of traditional ways of cooling system has ultimately increased CO? emission and depletion of CFC's are serious environmental issues which led scientific people to improve cooling techniques and eliminate use of CFC's. To reduce dependency on fossil fuels and 4environmental friendly system needed to be design. For being utilizing low grade energy source such as solar collector and reducing dependency on fossil fuel vapour absorption cooling system has shown a …