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Articles 1 - 16 of 16
Full-Text Articles in Engineering
Kinematic Synthesis Of Planar, Shape-Changing, Rigid Body Mechanisms For Design Profiles With Significant Differences In Arc Length, Shamsul A. Shamsudin, Andrew P. Murray, David H. Myszka, James P. Schmiedeler
Kinematic Synthesis Of Planar, Shape-Changing, Rigid Body Mechanisms For Design Profiles With Significant Differences In Arc Length, Shamsul A. Shamsudin, Andrew P. Murray, David H. Myszka, James P. Schmiedeler
Mechanical and Aerospace Engineering Faculty Publications
This paper presents a kinematic procedure to synthesize planar mechanisms capable of approximating a shape change defined by a general set of curves. These “morphing curves,” referred to as design profiles, differ from each other by a combination of displacement in the plane, shape variation, and notable differences in arc length. Where previous rigid-body shape-change work focused on mechanisms composed of rigid links and revolute joints to approximate curves of roughly equal arc length, this work introduces prismatic joints into the mechanisms in order to produce the different desired arc lengths. A method is presented to iteratively search along the …
Bridging The Gap Between Engineering Design And Pk-12 Curriculum Development Through The Use The Stem Education Quality Framework, Margaret Pinnell, James Rowley, Sandi Preiss, Rebecca P. Blust, Rebecca Beach, Suzanne Franco
Bridging The Gap Between Engineering Design And Pk-12 Curriculum Development Through The Use The Stem Education Quality Framework, Margaret Pinnell, James Rowley, Sandi Preiss, Rebecca P. Blust, Rebecca Beach, Suzanne Franco
Mechanical and Aerospace Engineering Faculty Publications
This paper will describe a unique partnership among the Department of Teacher Education and School of Engineering at the University of Dayton (UD) and the Dayton Regional STEM Center (DRSC). This partnership resulted in the development of the STEM Education Quality Framework (SQF), a tool to guide educators in teaching, learning and refining STEM education. The SQF resulted in a variety of educational tools, including a STEM curriculum template, that was implemented in the DRSCs teacher professional development and curriculum development program entitled the STEM Fellow Program. The STEM Fellow program was later modeled in a unique, NSF sponsored six …
Formulation To Predict Lower Limb Muscle Forces During Gait, Gil Serrancolí, Jonathan P. Walter, Allison Kinney, A. Barjau, Benjamin J. Fregly, Josep M. Font-Llagunes
Formulation To Predict Lower Limb Muscle Forces During Gait, Gil Serrancolí, Jonathan P. Walter, Allison Kinney, A. Barjau, Benjamin J. Fregly, Josep M. Font-Llagunes
Mechanical and Aerospace Engineering Faculty Publications
The human body has more muscles than Degrees of Freedom (DoF), and that leads to indeterminacy in the muscle force calculation. This study proposes the formulation of an optimization problem to estimate the lower-limb muscle forces during a gait cycle of a patient wearing an instrumented knee prosthesis. The originality of that formulation consists of simulating muscle excitations in a physiological way while muscle parameters are calibrated. Two approaches have been considered. In Approach A, measured contact forces are applied to the model and all inverse dynamics loads are matched in order to get a physiological calibration of muscle parameters. …
Lifting-Line Predictions For Induced Drag And Lift In Ground Effect, W. F. Phillips, Doug F. Hunsaker
Lifting-Line Predictions For Induced Drag And Lift In Ground Effect, W. F. Phillips, Doug F. Hunsaker
Mechanical and Aerospace Engineering Faculty Publications
Closed-form relations are presented for estimating ratios of the induced-drag and lift coefficients acting on a wing in ground effect to those acting on the same wing outside the influence of ground effect. The closed-form relations for these ground-effect influence ratios were developed by correlating results obtained from numerical solutions to Prandtl’s lifting-line theory. Results show that these influence ratios are not unique functions of the ratio of wing height to wingspan, as is sometimes suggested in the literature. These ground-effect influence ratios also depend on the wing planform, aspect ratio, and lift coefficient.
Synergies Controls Improve Prediction Of Knee Contact Forces And Muscle Excitations During Gait, Benjamin J. Fregly, Jonathan P. Walter, Allison Kinney, Scott A. Banks, Darryl D. D'Lima, Thor F. Besier, David G. Lloyd
Synergies Controls Improve Prediction Of Knee Contact Forces And Muscle Excitations During Gait, Benjamin J. Fregly, Jonathan P. Walter, Allison Kinney, Scott A. Banks, Darryl D. D'Lima, Thor F. Besier, David G. Lloyd
Mechanical and Aerospace Engineering Faculty Publications
This study investigates whether use of muscle excitation controls constructed from subjectspecific muscle synergy information can improve optimization prediction of knee contact forces and muscle excitations during walking. Muscle synergies quantify how a large number of experimental muscle electromyographic (EMG) signals can be reconstructed by linearly mixing a much smaller number of neural commands generated by the nervous system. Our hypothesis was that controlling all muscle excitations with a small set of experimentally calculated neural commands would improve prediction of knee contact forces and leg muscle excitations compared to using independently controlled muscle excitations.
Optimization Problem Formulation For Predicting Knee Muscle And Contact Forces During Gait, Gil Serrancolí, Jonathan P. Walter, Allison Kinney, Benjamin J. Fregly, Josep M. Font-Llagunes
Optimization Problem Formulation For Predicting Knee Muscle And Contact Forces During Gait, Gil Serrancolí, Jonathan P. Walter, Allison Kinney, Benjamin J. Fregly, Josep M. Font-Llagunes
Mechanical and Aerospace Engineering Faculty Publications
The human body has more muscles than degrees of freedom (DOF), which leads to indeterminacy in the muscle force calculation. In this study, an optimization problem to estimate the lower-limb muscle forces during a gait cycle of a patient wearing an instrumented knee prosthesis is formulated. It consists of simulating muscle excitations in a physiological way while muscle parameters are calibrated.
Momentum Theory With Slipstream Rotation Applied To Wind Turbines, Doug F. Hunsaker, W. F. Phillips
Momentum Theory With Slipstream Rotation Applied To Wind Turbines, Doug F. Hunsaker, W. F. Phillips
Mechanical and Aerospace Engineering Faculty Publications
A momentum theory which includes the effects of slipstream rotation for wind turbines is presented. The theory accounts for the axial and radial pressure gradients within the slipstream as well as the wake expansion caused by wake rotation. Because of the limiting approximations of previous methods, the effects of slipstream rotation have not been accurately realized. The method included here, which does not suffer from the unrealistic approximations of previous methods, predicts that the effects of slipstream rotation are manifest entirely through an increase in the turbine thrust coefficient. The method predicts, as previous methods do, that the Lanchester-Betz-Joukowski limit …
Lifting-Line Predictions For Induced Drag And Lift In Ground Effect, W. F. Phillips, Doug F. Hunsaker
Lifting-Line Predictions For Induced Drag And Lift In Ground Effect, W. F. Phillips, Doug F. Hunsaker
Mechanical and Aerospace Engineering Faculty Publications
Closed-form relations are presented for estimating ratios of the induced-drag and lift coefficients acting on a wing in ground effect to those acting on the same wing outside the influence of ground effect. The closed-form relations for these ground-effect influence ratios were developed by correlating results obtained from numerical solutions to Prandtl's lifting-line theory. Results show that these influence ratios are not unique functions of the ratio of wing height to wingspan, as is sometimes suggested in the literature. These ground-effect influence ratios also depend on the wing planform, aspect ratio, and lift coefficient.
Decomposed Lifting-Line Predictions And Optimization For Propulsive Efficiency Of Flapping Wings, W. F. Phillips, R. A. Miller, Doug F. Hunsaker
Decomposed Lifting-Line Predictions And Optimization For Propulsive Efficiency Of Flapping Wings, W. F. Phillips, R. A. Miller, Doug F. Hunsaker
Mechanical and Aerospace Engineering Faculty Publications
A decomposed Fourier series solution to Prandtl's classical lifting-line theory is used to predict the lift, induced-thrust, and power coefficients developed by a flapping wing. A significant advantage of this quasi-steady analytical solution over commonly used numerical methods is the utility provided for optimizing wing flapping cycles. The analytical solution involves five time-dependent functions that could all be optimized to maximize thrust, propulsive efficiency, and/or other performance measures. Results show that by optimizing only two of these five functions, propulsive efficiencies exceeding 97% can be obtained. Results are presented for untwisted rectangular wings in pure plunging, rectangular wings with linear …
Energy-Vorticity Turbulence Model With Application To Flow Near Rough Surfaces, W. F. Phillips, E. B. Fowler, Doug F. Hunsaker
Energy-Vorticity Turbulence Model With Application To Flow Near Rough Surfaces, W. F. Phillips, E. B. Fowler, Doug F. Hunsaker
Mechanical and Aerospace Engineering Faculty Publications
Based on a more direct analogy between turbulent and molecular transport, a foundation is presented for an energy–vorticity turbulence model. Whereas traditional k-εk-ε, k-ωk-ω, and k-ζk-ζ models relate the eddy viscosity to a dissipation length scale associated with the smaller eddies having the highest strain rates, the proposed model relates the eddy viscosity to a mean vortex wavelength associated with the larger eddies primarily responsible for turbulent transport. A rigorous development of the turbulent-energy-transport equation from the Navier–Stokes equations includes exact relations for the viscous dissipation and molecular transport of turbulent kinetic energy. Application of Boussinesq’s analogy between turbulent and …
End-Of-Life Management Of Crystalline Silicon Photovoltaic Module, Jun-Ki Choi
End-Of-Life Management Of Crystalline Silicon Photovoltaic Module, Jun-Ki Choi
Mechanical and Aerospace Engineering Faculty Publications
PV manufacturing has been growing over the past 10 years and further annual growth of 15% is expected until 2020. A study on positioning a grand plan for solar power shows how vast PV arrays and other renewable energies can provide significant amount of electricity and total energy needs by 2050. Various new PV technologies have been introduced in the market and existing technologies have undergone further development. How all these developments will affect the fate of the end-of-life PV modules is uncertain. In addition, the market price of some rare earth materials utilized in the manufacturing of the various …
Muscle Synergies Improve Estimation Of Knee Contact Forces During Walking, Benjamin J. Fregly, Jonathan P. Walter, Allison Kinney, Scott A. Banks, Darryl D. D'Lima, Thor F. Besier, David G. Lloyd
Muscle Synergies Improve Estimation Of Knee Contact Forces During Walking, Benjamin J. Fregly, Jonathan P. Walter, Allison Kinney, Scott A. Banks, Darryl D. D'Lima, Thor F. Besier, David G. Lloyd
Mechanical and Aerospace Engineering Faculty Publications
This study investigates whether use of subject-specific muscle synergies can improve optimization predictions of muscle excitation patterns and knee contact forces during walking. Muscle synergies describe how a small number of neural commands generated by the nervous system can be linearly combined to produce the broad range of muscle electromyographic (EMG) signals measured experimentally. By quantifying the interdependence of individual EMG signals, muscle synergies provide dimensionality reduction for the neural control redundancy problem. Our hypothesis was that use of subjectspecific muscle synergies to limit muscle excitation patterns would improve prediction of muscle EMG patterns at the hip, knee, and ankle …
Assess The Accuracy Of The Variational Asymptotic Plate And Shell Analysis Using The Generalized Uni, Luciano Demasi, Wenbin Yu
Assess The Accuracy Of The Variational Asymptotic Plate And Shell Analysis Using The Generalized Uni, Luciano Demasi, Wenbin Yu
Mechanical and Aerospace Engineering Faculty Publications
The accuracy of the Variational Asymptotic Plate and Shell Analysis (VAPAS) is assessed against several higher order, zig zag and layerwise theories generated by using the invariant axiomatic framework denoted as Generalized Unified Formulation (GUF). These theories are also compared against the elasticity solution developed for the case of a sandwich structure with high Face to Core Stiffness Ratio. GUF allows to use an infinite number of axiomatic theories (Equivalent Single Layer theories with or without zig zag effects and Layerwise theories as well) with any combination of orders of the displacements and it is an ideal tool to precisely …
Thermal Conductivity Profile Determination In Proton-Irradiated Zrc By Spatial And Frequency Scanning Thermal Wave Methods, C. Jensen, M. Chirtoc, N. Horny, J. S. Antoniow, H. Pron, Heng Ban
Thermal Conductivity Profile Determination In Proton-Irradiated Zrc By Spatial And Frequency Scanning Thermal Wave Methods, C. Jensen, M. Chirtoc, N. Horny, J. S. Antoniow, H. Pron, Heng Ban
Mechanical and Aerospace Engineering Faculty Publications
Using complementary thermal wave methods, the irradiation damaged region of zirconium carbide (ZrC) is characterized by quantifiably profiling the thermophysical property degradation. The ZrC sample was irradiated by a 2.6 MeV proton beam at 600 °C to a dose of 1.75 displacements per atom. Spatial scanning techniques including scanning thermal microscopy (SThM), lock-in infrared thermography (lock-in IRT), and photothermal radiometry (PTR) were used to directly map the in-depth profile of thermal conductivity on a cross section of the ZrC sample. The advantages and limitations of each system are discussed and compared, finding consistent results from all techniques. SThM provides the …
Dnad, A Simple Tool For Automatic Differentiation Of Fortran Codes Using Dual Numbers, Wenbin Yu, Maxwell Blair
Dnad, A Simple Tool For Automatic Differentiation Of Fortran Codes Using Dual Numbers, Wenbin Yu, Maxwell Blair
Mechanical and Aerospace Engineering Faculty Publications
DNAD (dual number automatic differentiation) is a simple, general-purpose tool to automatically differentiate Fortran codes written in modern Fortran (F90/95/2003) or legacy codes written in previous version of the Fortran language. It implements the forward mode of automatic differentiation using the arithmetic of dual numbers and the operator overloading feature of F90/95/2003. Very minimum changes of the source codes are needed to compute the first derivatives of Fortran programs. The advantages of DNAD in comparison to other existing similar computer codes are its programming simplicity, extensibility, and computational efficiency. Specifically, DNAD is more accurate and efficient than the popular complex-step …
A Closed-Form Solution For The Similarity Transformation Parameters Of Two Planar Point Sets, Shamsul A. Shamsudin, Andrew P. Murray
A Closed-Form Solution For The Similarity Transformation Parameters Of Two Planar Point Sets, Shamsul A. Shamsudin, Andrew P. Murray
Mechanical and Aerospace Engineering Faculty Publications
Image registration covers the set of techniques used in matching images of the same scene. A subset of the image registration problem, identifying the parameters in a similarity transformation, has emerged as useful in a recently defined area of machine design: designing mechanisms for rigidbody shape-change. First, this brief paper shows a potential use for image registration techniques outside the field of machine vision. Second, it presents a closed-form solution for the similarity transformation parameters when the point sets to be matched are restricted to two-dimensional space as is needed in the aforementioned design problem.