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Articles 1  19 of 19
FullText Articles in Mechanical Engineering
The Spectral Center Of Gravity Effect And Auditory Filter Bandwidth, Marc Fagelson, Linda M. Thibodeau
The Spectral Center Of Gravity Effect And Auditory Filter Bandwidth, Marc Fagelson, Linda M. Thibodeau
Marc A. Fagelson
Simulation Of Active Control Of Asymmetric Flows Around Slender Pointed Forebodies, Hazem Sharaf ElDin
Simulation Of Active Control Of Asymmetric Flows Around Slender Pointed Forebodies, Hazem Sharaf ElDin
Mechanical & Aerospace Engineering Theses & Dissertations
At high angles of attack, the flowfield over slender forebodies becomes asymmetric with substantial side force, which may exceed the available control capability. The unsteady compressible NavierStokes equations are used to investigate the effectiveness of different active control methods to alleviate and possibly eliminate the flow asymmetry and the subsequent side force. Although the research work focuses on active control methods, a passive control method has been investigated. The implicit, Roe fluxdifference splitting, finite volume scheme is used for the numerical computations. Both locallyconical and threedimensional solutions of the NavierStokes equations are obtained.
The asymmetric flow over fivedegree semiapex angle ...
Nc Milling Error Assessment And Tool Path Correction, Yunching Huang, James H. Oliver
Nc Milling Error Assessment And Tool Path Correction, Yunching Huang, James H. Oliver
Mechanical Engineering Conference Presentations, Papers, and Proceedings
A system of algorithms is presented for material removal simulation, dimensional error assessment and automated correction of Þveaxis numerically controlled (NC) milling tool paths. The methods are based on a spatial partitioning technique which incorporates incremental proximity calculations between milled and design surfaces. Hence, in addition to realtime animated Þveaxis milling simulation, milling errors are measured and displayed simultaneously. Using intermediate error assessment results, a reduction of intersection volume algorithm is developed to eliminate gouges on the workpiece via tool path correction. Finally, the view dependency typical of previous spatial partitioningbased NC simulation methods is overcome by a contour display ...
A Recursive Least Squares Training Algorithm For Multilayer Recurrent Neural Networks, Q. Xu, K. Krishnamurthy, Bruce M. Mcmillin, Wen Feng Lu
A Recursive Least Squares Training Algorithm For Multilayer Recurrent Neural Networks, Q. Xu, K. Krishnamurthy, Bruce M. Mcmillin, Wen Feng Lu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Recurrent neural networks have the potential to perform significantly better than the commonly used feedforward neural networks due to their dynamical nature. However, they have received less attention because training algorithms/architectures have not been well developed. In this study, a recursive least squares algorithm to train recurrent neural networks with an arbitrary number of hidden layers is developed. The training algorithm is developed as an extension of the standard recursive estimation problem. Simulated results obtained for identification of the dynamics of a nonlinear dynamical system show promising results.
Identification Of Cutting Force In End Milling Operations Using Recurrent Neural Networks, Q. Xu, K. Krishnamurthy, Bruce M. Mcmillin, Wen Feng Lu
Identification Of Cutting Force In End Milling Operations Using Recurrent Neural Networks, Q. Xu, K. Krishnamurthy, Bruce M. Mcmillin, Wen Feng Lu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The problem of identifying the cutting force in end milling operations is considered in this study. Recurrent neural networks are used here and are trained using a recursive least squares training algorithm. Training results for data obtained from a SAJO 3axis vertical milling machine for steady slot cuts are presented. The results show that a recurrent neural network can learn the functional relationship between the feed rate and steadystate average resultant cutting force very well. Furthermore, results for the MackeyGlass time series prediction problem are presented to illustrate the faster learning capability of the neural network scheme presented here
Unsteady Flow Simulations About Moving Boundary Configurations Using Dynamic Domain Decomposition Techniques, GuanWei Yen
Unsteady Flow Simulations About Moving Boundary Configurations Using Dynamic Domain Decomposition Techniques, GuanWei Yen
Mechanical & Aerospace Engineering Theses & Dissertations
A computational method is developed to solve the coupled governing equations of an unsteady flowfield and those of rigidbody dynamics in six degreesoffreedom (6DOF). This method is capable of simulating the unsteady flowfields around multiple component configurations with at least one of the components in relative motion with respect to the others. Two of the important phenomena that such analyses can help us to understand are the unsteady aerodynamic interference and the boundaryinduced component of such a flowfield. By hybridizing two dynamic domain decomposition techniques, the grid generation task is simplified, the computer memory requirement is reduced, and the governing ...
Flow Simulations About SteadyComplex And Unsteady Moving Configurations Using StructuredOverlapped And Unstructured Grids, James Charles Newman Iii
Flow Simulations About SteadyComplex And Unsteady Moving Configurations Using StructuredOverlapped And Unstructured Grids, James Charles Newman Iii
Mechanical & Aerospace Engineering Theses & Dissertations
The limiting factor in simulating flows past realistic configurations of interest has been the discretization of the physical domain on which the governing equations of fluid flow may be solved. In an attempt to circumvent this problem, many Computational Fluid Dynamic (CFD) methodologies that are based on different grid generation and domain decomposition techniques have been developed. However, due to the costs involved and expertise required, very few comparative studies between these methods have been performed. In the present work, the two CFD methodologies which show the most promise for treating complex threedimensional configurations as well as unsteady moving boundary ...
Click‐Evoked Otoacoustic Emissions In Normal‐Hearing Children, Jacek Smurzynski
Click‐Evoked Otoacoustic Emissions In Normal‐Hearing Children, Jacek Smurzynski
Jacek Smurzynski
Advanced Fuzzy Logic Controllers And SelfTuning Strategy , ShouHeng Huang
Advanced Fuzzy Logic Controllers And SelfTuning Strategy , ShouHeng Huang
Retrospective Theses and Dissertations
This study has concentrated on fuzzy logic controllers from the basic aspects to an advanced selftuning strategy. Fuzzy logic provides a very good technique for knowledge representation which makes it possible to incorporate the experience of human operators in the design of controllers;The basic concepts of fuzzy set theory, fundamental definitions of fuzzy logic, and basic structure of fuzzy logic controllers are introduced and a guideline for building the fuzzy rulebased system is developed. The rule development and adjustment strategies for fuzzy logic controllers are presented and experimentally identified. The fuzzy logic control system is analyzed on a linguistic ...
Development Of Strength Theories For Random Fiber Composites, Victor Giurgiutiu
Development Of Strength Theories For Random Fiber Composites, Victor Giurgiutiu
Faculty Publications
A ressessment of existing theories for calculating the strength of random and quasirandom fiber composites is presented. Fundamental aspects regarding the physical model, macromechanics analysis, fiber distribution functions, generalized failure criterion, and progressive versus sudden failure models are covered first. Progressive ductile failure, progressive brittle failure, and sudden brittle failure are treated in detail. In each case, the original theory is briefly reviewed, and then its extensions accompanied by numerical examples are presented. Several limitations originally imposed by Hahn, such as the monotonically nonincreasing requirement on the failure strain curve, are lifted and the mathematical formulations are generalized. Some common ...
Modelling And Evaluation Of A CisternBased GroundCoupled Heat Pump: Its Implications In Reducing Energy In A Commercial Swine Operation , James D. Leary
Modelling And Evaluation Of A CisternBased GroundCoupled Heat Pump: Its Implications In Reducing Energy In A Commercial Swine Operation , James D. Leary
Retrospective Theses and Dissertations
This research details the analysis of a groundcoupled heat pump system which utilizes a 20,000 gallon wellwater storage tank as a source of heating and cooling. It addresses the feasibility of such a system and discusses the system in terms of energy efficiencyfirst law conservation analysis. The potential use of this type of system for the control of sensitive thermal environments involving swine is also evaluated;The goal of this research was to investigate ISU's SNMRC heat pump system. Specific objectives were: (1) To evaluate the system in terms of heat exchanger and heat pump efficiencies. (2) To ...
Efficient Inversion Of Fourier And Laplace Domain Boundary Element Solutions For Elastodynamic Scattering , Joel Kevin Ness
Efficient Inversion Of Fourier And Laplace Domain Boundary Element Solutions For Elastodynamic Scattering , Joel Kevin Ness
Retrospective Theses and Dissertations
In ultrasonic nondestructive testing, the actual time domain signature of a scattered wave due to a pulsed input is the common observable (via oscilloscope) quantity. Numerically simulated solutions are thus desirable in the time domain. These can be obtained by working directly in the time domain or by inversions of integral transform solutions in the frequency (Fourier) or Laplace domains. Direct time solutions are suitable for short times but generally deteriorate for longer times. Alternately, the transform techniques generally require solutions over a wide spectrum in the transform variable to provide accurate inversions back to the time domain. However, without ...
Active Noise Control In A ThreeDimensional Space , Jihe Yang
Active Noise Control In A ThreeDimensional Space , Jihe Yang
Retrospective Theses and Dissertations
In this research, a new approach is presented for optimizing the performance of active noise control in threedimensional space. The work focuses on the critical role of determining the locations for secondary sources in active noise suppression. A systematic technique is proposed for estimating optimal locations of secondary sources on the boundary of a threedimensional domain for both local and global active control of harmonic sound fields. The theoretical foundation of this work is Huygen's principle. The indirect boundary element method (IBEM) which is a numerical implementation of Huygen's principle is employed as a basis for the numerical ...
Several Considerations Regarding The Variable Length Blade Rotor, Bogdan Popescu, Victor Giurgiutiu
Several Considerations Regarding The Variable Length Blade Rotor, Bogdan Popescu, Victor Giurgiutiu
Faculty Publications
No abstract provided.
Multigrid Acceleration Of TimeDependent Solutions Of NavierStokes Equations, Sarafa Oladele Ibraheem
Multigrid Acceleration Of TimeDependent Solutions Of NavierStokes Equations, Sarafa Oladele Ibraheem
Mechanical & Aerospace Engineering Theses & Dissertations
Recent progress in Computational Fluid Dynamics is encouraging scientists to look at fine details of flow physics of problems in which natural unsteady phenomena have hitherto been neglected. The acceleration methods that have proven very successful in steady state computations can be explored for time dependent computations. In this work, an efficient multigrid methods is developed to solve the timedependent Euler and NavierStokes equations. The BeamWarming ADI method is used as the base algorithm for time stepping calculations. Application of the developed algorithm proved very efficient in selected steady and unsteady test problems. For instance, the inherent unsteadiness present in ...
Spline Network Modeling And Fault Classification Of A Heating Ventilation And AirConditioning System , Mathew Scaria Chackalackal
Spline Network Modeling And Fault Classification Of A Heating Ventilation And AirConditioning System , Mathew Scaria Chackalackal
Retrospective Theses and Dissertations
A spline network, that is an alternative to artificial neural networks, is introduced in this dissertation. This network has an input layer, a single hidden layer, and an output layer. Spline basis functions, with small support, are used as the activation functions. The network is used to model the steady state operation of a complex Heating Ventilation and Airconditioning (HVAC) system. Real data was used to train the spline network. A neural network was also trained on the same set of data. Based on the training process, it is possible to conclude that when compared to artificial neural networks, the ...
Characterization And Analysis Of Viscoelastically Loaded Thin Film Piezoelectric Resonators Incorporated In An Oscillator Microsensing System , Ronald Patrick O'Toole
Characterization And Analysis Of Viscoelastically Loaded Thin Film Piezoelectric Resonators Incorporated In An Oscillator Microsensing System , Ronald Patrick O'Toole
Retrospective Theses and Dissertations
In the recent advancement of piezoelectric resonator technology, there has been a large growth in the application of these devices for chemical sensing. These sensors operate by detecting changes in their environment which perturb the electrical  acoustic operation and in turn can be harnessed by means of supporting electronics and signal processing to monitor various processes. Examples include remote environmental monitoring, chemical process control, and commercial gas phase detectors. In this dissertation, the chemical sensing theory and properties of piezoelectric resonators such as the bulkacoustic wave thinfilm resonator (TFR) and the quartz crystal microbalance (QCM) are developed. This analysis concentrates ...
A Fringe Center Detection Technique Based On A SubPixel Resolution, And Its Applications Using Sinusoidal Gratings, Ming Chang, Paul P. Lin, Wen Chih Tai
A Fringe Center Detection Technique Based On A SubPixel Resolution, And Its Applications Using Sinusoidal Gratings, Ming Chang, Paul P. Lin, Wen Chih Tai
Mechanical Engineering Faculty Publications
A common problem in optical profilometry is the accuracy in locating fringe centers. This paper presents an accurate fringe center detection technique based on subpixel resolution using the fringe projection method. An optimum reconstruction filter is developed which has low sensitivity to noise. In fringe center detection, computer simulation results of using onepixel and subpixel resolutions are compared. The detection technique is then applied to radius measurement of cylindrical objects and surface profile measurement of diffuse objects. The experimental results thus obtained through the proposed optimum reconstruction filter show significant improvement in measurement accuracy.
Directional Wave Spectra Using An Acoustic Doppler Current Profiler, William T. Stockhausen
Directional Wave Spectra Using An Acoustic Doppler Current Profiler, William T. Stockhausen
Dissertations, Theses, and Masters Projects
No abstract provided.