Dissertations / Theses: 'Mechanical engineering. Computer systems. Mechanics'

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Wu, Fei. "Parallel computational methods for constrained mechanical systems." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282561.

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Two methods suitable for parallel computation in the study of mechanical systems with holonomic and nonholonomic constraints are presented: one is an explicit solution based on generalized inverse algebra; the second solves problems of this class through the direct application of Gauss' principle of least constraint and genetic algorithms. Algorithms for both methods are presented for sequential and parallel implementations. The method using generalized inverses is able to solve problems that involve redundant, degenerate and intermittent constraints, and can identify inconsistent constraint sets. It also allows a single program to perform pure kinematic and dynamic analyses. Its computational cost is among the lowest in comparison with other methods. In addition, constraint violation control methods are investigated to improve integration accuracy and further reduce computational cost. Constrained dynamics problems are also solved using optimization methods by applying Gauss' principle directly. An objective function that incorporates constraints is derived using a symmetric scheme, which is implemented using genetic algorithms in a parallel computing environment. It is shown that this method is capable of solving the same cases of constraints as the former method. Examples and numerical experiments demonstrating the applications of the two methods to constrained multiparticle and multibody systems are presented.

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Feng, Chieh-Chuan. "Sliding control design and implementation on a single-link flexible arm." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA242714.

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Thesis (M.S. in Mechanical Engineering and Mechanical Engineer)--Naval Postgraduate School, December 1990.
Thesis Advisor(s): Chang, Liang-Wey. "December 1990." Description based on title screen as viewed on March 30, 2010. DTIC Identifier(s): Sliding Mode Control Systems, Sliding control Algorithms, Program Listings, Theses. Author(s) subject terms: Sliding Mode Control, Flexible Arm, Control of Flexible Arm, Uncertainty. Includes bibliographical references (p. 116). Also available in print.

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Yedeg, Esubalewe Lakie. "Control and design of engineering mechanics systems." Licentiate thesis, Umeå universitet, Institutionen för datavetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-76675.

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Chen, Joseph E. "An interactive computer tool for imprecise calculations in engineering systems." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/35018.

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Pearce, Jonathan P. (Jonathan Patrick) 1978. "Qualitative behavior prediction for simple mechanical systems." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86692.

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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.
Includes bibliographical references (p. 55-56).
by Jonathan P. Pearce.
M.Eng.

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Bessent, Paul. "Structure Climbing Monkey Robot." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/508.

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This report describes the design, building, and testing of the Structure Climbing Monkey Robot (SCMR). It is composed of seven successive joints and linkages with two grippers at the two ends. Each gripper can act as the base or the end of the robot. The SCMR has the ability to climb any structure. The gripper plates can be changed to grab different kinds of structures, but this one is made to grab 2x4‘s. A program was written to assist the user to grab four non-coplanar, non-orthogonal points. The SCMR is actuated by a total of nine motors: two to open and close the two grippers and seven to control the movement of the SCMR. Planetary gear motors are used with a worm gear to control the motion of each joint. The worm gear increases the torque of the motor and reduces the rotational speed to a usable value. The SCMR is just over 45 inches long and weighs about 30 pounds. The motion of the SCMR is controlled by the microcontroller Arduino Mega 2560, Vex Robotic quadrature encoders, and Pololu 18v15 motor driver chips. Code was written in the languages Arduino and Processing to actuate the motors and create the GUI, respectively. The motors can be controlled individually or run simultaneously while incrementing a specified angle.

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Yedeg, Esubalewe Lakie. "Analysis, Control, and Design Optimization of Engineering Mechanics Systems." Doctoral thesis, Umeå universitet, Institutionen för datavetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-119978.

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This thesis considers applications of gradient-based optimization algorithms to the design and control of some mechanics systems. The material distribution approach to topology optimization is applied to design two different acoustic devices, a reactive muffler and an acoustic horn, and optimization is used to control a ball pitching robot. Reactive mufflers are widely used to attenuate the exhaust noise of internal combustion engines by reflecting the acoustic energy back to the source. A material distribution optimization method is developed to design the layout of sound-hard material inside the expansion chamber of a reactive muffler. The objective is to minimize the acoustic energy at the muffler outlet. The presence or absence of material is represented by design variables that are mapped to varying coefficients in the governing equation. An anisotropic design filter is used to control the minimum thickness of materials separately in different directions. Numerical results demonstrate that the approach can produce mufflers with high transmission loss for a broad range of frequencies. For acoustic devices, it is possible to improve their performance, without adding extended volumes of materials, by an appropriate placement of thin structures with suitable material properties. We apply layout optimization of thin sound-hard material in the interior of an acoustic horn to improve its far-field directivity properties. Absence or presence of thin sound-hard material is modeled by a surface transmission impedance, and the optimization determines the distribution of materials along a “ground structure” in the form of a grid inside the horn. Horns provided with the optimized scatterers show a much improved angular coverage, compared to the initial configuration. The surface impedance is handled by a new finite element method developed for Helmholtz equation in the situation where an interface is embedded in the computational domain. A Nitschetype method, different from the standard one, weakly enforces the impedance conditions for transmission through the interface. As opposed to a standard finite-element discretization of the problem, our method seamlessly handles both vanishing and non-vanishing interface conditions. We show the stability of the method for a quite general class of surface impedance functions, provided that possible surface waves are sufficiently resolved by the mesh. The thesis also presents a method for optimal control of a two-link ball pitching robot with the aim of throwing a ball as far as possible. The pitching robot is connected to a motor via a non-linear torsional spring at the shoulder joint. Constraints on the motor torque, power, and angular velocity of the motor shaft are included in the model. The control problem is solved by an interior point method to determine the optimal motor torque profile and release position. Numerical experiments show the effectiveness of the method and the effect of the constraints on the performance.

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Sturnick, Gerald R. "Integration of computer-aided design techniques into the mechanical product development process /." Online version of thesis, 1989. http://hdl.handle.net/1850/10477.

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Ask, Olsson Jacob, and Fredrik Dehlin. "Modelling and Simulation of Conservative Dynamical Systems by Computer Algebra Assisted Lagrangian Mechanics." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-210793.

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Conservative dynamical systems is modelled with Lagrangian mechanics using Maple TM with the KTH developed plug-in symbolic package Sophia and simulated using Matlab®. Two double pendulum configurations and an object in a Keplerian orbit is studied. Motions and phase portraits are analysed, and numerical verifications of Kepler’s laws are performed. Properties concerning chaos is determined partly by examining sensitivity to initial conditions and it is shown that the 2D pendulum exhibits non-periodic behaviour whilst the 3D pendulum exhibits chaotic behaviour. Kepler’s laws are reproduced under certain assumptions. Finally, the applicability of Lagrangian mechanics when applied to conservative dynamical systems is evaluated.

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Cziulik, Carlos. "Development of a computer evaluation model for assessing mechanical systems conceptual design alternatives." Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/843915/.

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The focus of this thesis is on the development of a conceptual design evaluation model that can be used in engineering design and can be implemented as a computer tool. A prerequisite to achieve this objective is a proper understanding of the initial phases of the design process, using an adequate framework. Hence, a brief examination of Theory of Technical Systems associated to a comprehensive study of the conceptual design stage, based on academic design methodologies and a survey amongst British industries, is presented. Additionally, evaluation issues at the early phases of design and a number of approaches for evaluating alternative solutions are investigated and relevant characteristics to be included in a prospective conceptual design evaluation model are compiled. A novel evaluation model based on function metrics has been proposed. The approach provides an intermediate evaluation, indicating which solutions have the potential to progress further in the design process The core of the model is the composition of evaluation matrices and computation of partial indices, which will originate an overall index used to classify the alternatives. The model assumes the existence of an explicit function structure on which the development of the organ/component structure is going to be based. A unique feature of this model is that it does not depend on designers' preferences or judgement in assigning values. From the formalised solution the designer has to identify which organ/component implements which function. An initial prototype of a computer tool (LiberSolutio), which embodies the above model, is presented. In addition to being an evaluation system, LiberSolutio can record the design history of the set of solutions generated for a particular functional decomposition/ structure. A preliminary evaluation of the model and computer system is also presented with conclusions drawn from the results obtained.

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Ouellette, Mark Paul. "Form verification for the conceptual design of complex mechanical systems." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/18237.

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Tesiero, Raymond Charles III. "Intelligent approaches for modeling and optimizing HVAC systems." Thesis, North Carolina Agricultural and Technical State University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3672500.

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Advanced energy management control systems (EMCS), or building automation systems (BAS), offer an excellent means of reducing energy consumption in heating, ventilating, and air conditioning (HVAC) systems while maintaining and improving indoor environmental conditions. This can be achieved through the use of computational intelligence and optimization. This research will evaluate model-based optimization processes (OP) for HVAC systems utilizing MATLAB, genetic algorithms and self-learning or self-tuning models (STM), which minimizes the error between measured and predicted performance data. The OP can be integrated into the EMCS to perform several intelligent functions achieving optimal system performance. The development of several self-learning HVAC models and optimizing the process (minimizing energy use) will be tested using data collected from the HVAC system servicing the Academic building on the campus of NC A&T State University.

Intelligent approaches for modeling and optimizing HVAC systems are developed and validated in this research. The optimization process (OP) including the STMs with genetic algorithms (GA) enables the ideal operation of the building's HVAC systems when running in parallel with a building automation system (BAS). Using this proposed optimization process (OP), the optimal variable set points (OVSP), such as supply air temperature (T_s), supply duct static pressure (P_s), chilled water supply temperature (T_w), minimum outdoor ventilation, reheat (or zone supply air temperature, T_z), and chilled water differential pressure set-point (D_pw) are optimized with respect to energy use of the HVAC's cooling side including the chiller, pump, and fan. HVAC system component models were developed and validated against both simulated and monitored real data of an existing VAV system. The optimized set point variables minimize energy use and maintain thermal comfort incorporating ASHRAE's new ventilation standard 62.1-2013. The proposed optimization process is validated on an existing VAV system for three summer months (May, June, August).

This proposed research deals primarily with: on-line, self-tuning, optimization process (OLSTOP); HVAC design principles; and control strategies within a building automation system (BAS) controller. The HVAC controller will achieve the lowest energy consumption of the cooling side while maintaining occupant comfort by performing and prioritizing the appropriate actions. Recent technological advances in computing power, sensors, and databases will influence the cost savings and scalability of the system. Improved energy efficiencies of existing Variable Air Volume (VAV) HVAC systems can be achieved by optimizing the control sequence leading to advanced BAS programming. The program's algorithms analyze multiple variables (humidity, pressure, temperature, CO₂, etc.) simultaneously at key locations throughout the HVAC system (pumps, cooling coil, chiller, fan, etc.) to reach the function's objective, which is the lowest energy consumption while maintaining occupancy comfort.

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Zohur, Abdul. "Micro-Electro-Mechanical Systems (MEMS) Integrated Frequency Reconfigurable Antenna." DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/1731.

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In this paper, the design, analysis, and characterization of reconfigurable antennas based on radio frequency micro-electro-mechanical systems (RF MEMS) operating in the United States' public safety (PS) bands are presented. The design methodology of these antennas, which are different from the normal antenna design, is also reported. In this thesis, two electrically small reconfigurable antenna designs have been presented, with two and three modes of operation, and central frequencies of 718 and 4960 MHz and of 857,809 and 4960 MHz, respectively. The maximum frequency tunable ratio achieved in these designs is 7. The recongurability between the modes is achieved by one and three RF MEMS switches in all three designs. These switches enable a change in the length of the current flow path, thereby changing the resonance frequencies. The measurement results for impedance and radiation characteristics of the fabricated antennas prototypes are also presented, and agree reasonably well with the simulations results from An-soft HFSS.

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Amirtharajah, Rajeevan. "Design of a low power VLSI systems powered by ambient mechanical vibration." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9439.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.
Includes bibliographical references (p. 161-166).
Low power design trends raise the possibility of using ambient energy to power future digital systems. This thesis explores the design of such systems for collecting and processing data from sensors. The low throughput requirements of this type of computation allows aggressive scaling of supply voltages and enables very low power solutions. We discuss implementations of a generator for transducing mechanical vibration to electrical energy using macroscopic and MEMS technology. A DC/DC converter chip has been designed and tested to demonstrate the feasibility of operating a digital system from power generated by vibrations in its environment. A moving coil electromagnetic transducer was used as a power generator. A single generator excitation produced 23 ms of valid DSP operation at a 500 kHz clock frequency, corresponding to 11,700 cycles. An ultra low power DSP chip has also been designed that implements a power scalable detection and classification algorithm for a biomedical sensor. This chip demonstrates appropriate architectural and circuit techniques for low to medium throughput sensor applications. It consumes 550 n W at 1.5 V with a 1 kHz clock frequency.
by Rajeevan Amirtharajah.
Ph.D.

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Olfati-Saber, Reza. "Nonlinear control of underactuated mechanical systems with application to robotics and aerospace vehicles." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8979.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.
Includes bibliographical references (leaves 308-316).
This thesis is devoted to nonlinear control, reduction, and classification of underactuated mechanical systems. Underactuated systems are mechanical control systems with fewer controls than the number of configuration variables. Control of underactuated systems is currently an active field of research due to their broad applications in Robotics, Aerospace Vehicles, and Marine Vehicles. The examples of underactuated systems include flexible-link robots, nobile robots, walking robots, robots on mobile platforms, cars, locomotive systems, snake-type and swimming robots, acrobatic robots, aircraft, spacecraft, helicopters, satellites, surface vessels, and underwater vehicles. Based on recent surveys, control of general underactuated systems is a major open problem. Almost all real-life mechanical systems possess kinetic symmetry properties, i.e. their kinetic energy does not depend on a subset of configuration variables called external variables. In this work, I exploit such symmetry properties as a means of reducing the complexity of control design for underactuated systems. As a result, reduction and nonlinear control of high-order underactuated systems with kinetic symmetry is the main focus of this thesis. By "reduction", we mean a procedure to reduce control design for the original underactuated system to control of a lowerorder nonlinear or mechanical system. One way to achieve such a reduction is by transforming an underactuated system to a cascade nonlinear system with structural properties. If all underactuated systems in a class can be transformed into a specific class of nonlinear systems, we refer to the transformed systems as the "normal form" of the corresponding class of underactuated systems. Our main contribution is to find explicit change of coordinates and control that transform several classes of underactuated systems, which appear in robotics and aerospace applications, into cascade nonlinear systems with structural properties that are convenient for control design purposes. The obtained cascade normal forms are three classes of nonlinear systems, namely, systems in strict feedback form, feedforward form, and nontriangular linear-quadratic form. The names of these three classes are due to the particular lower-triangular, upper-triangular, and nontriangular structure in which the state variables appear in the dynamics of the corresponding nonlinear systems. The triangular normal forms of underactuated systems can be controlled using existing backstepping and feedforwarding procedures. However, control of the nontriangular normal forms is a major open problem. We address this problem for important classes of nontriangular systems of interest by introducing a new stabilization method based on the solutions of fixed-point equations as stabilizing nonlinear state feedback laws. This controller is obtained via a simple recursive method that is convenient for implementation. For special classes of nontriangular nonlinear systems, such fixed-point equations can be solved explicitly ...
by Reza Olfati-Saber.
Ph.D.

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Wang, Xin 1972 Jan 8. "FastStokes : a fast 3-D fluid simulation program for micro-electro-mechanical systems." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/29229.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.
Includes bibliographical references (p. 150-153).
We have developed boundary integral equation formulas and a corresponding fast 3-D Stokes flow simulation program named FastStokes to accurately simulate viscous drag forces on geometrically complicated MEMS (micro- electro- mechanical systems) devices. Unlike the 3-D finite element or finite difference solvers which often take days to run to completion or fail when geometry gets complicated, the FastStokes 3.0 simulation program is capable of simulating complicated devices such as resonators, accelerometers, and micro-mirrors on PC computers in minutes. The FastStokes 3.0 simulation program is a fast 3-D boundary-element simulation program that uses only surface discretizations. The implementation of the Precorrected-FFT algorithm in combination with the GMRES algorithm substantially improves the speed of this simulation program. An efficient two-step approach that successfully handles the null space of the singular incompressible Stokes BEM operators is developed to avoid numerical errors and solution discontinuities. An analytical flat-panel kernel integration algorithm is implemented in FastStokes and an accurate curved-panel integration algorithm is also developed. Both an incompressible FastStokes solver and a compressible FastStokes solver have been developed and tested. They are not only fast, but also accurate. The incompressible FastStokes solver solves the steady incompressible Stokes equation; the effectiveness of this fast solver has been repeatedly proved by the close matches between numerical simulation results and experiments, within engineering accuracy (5-10% error).
(cont.) The numerical simulation results of a comb drive resonator, the ADXL 76 accelerometer, and a micro-mirror are given. The compressible FastStokes solver solves a linearized compressible Stokes equation that is also capable of capturing the weak air compression effect in MEMS devices. Therefore, the compressible FastStokes solver is a more general simulation program, and it is especially useful when the strength of the fluid compression effect is uncertain. The solutions of the compressible FastStokes are compared with the analytical solutions of the linearized compressible Reynolds equation. Numerical simulations of some common structures that may exhibit compression effect when packaged in gases are also given.
by Xin Wang.
Ph.D.

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Wehage, Kristopher. "Computational Methods for Dynamics and Mobility Analysis of Multiloop Mechanisms and Robotic Systems." Thesis, University of California, Davis, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10256858.

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In this work, a systematic method based on graph theoretic concepts is presented that allows setting up a general mechanism's governing equations and analyzing transmission performance for a wide range of parametric and topological variations. The algorithms and methods described in this work are designed to be both fully automatic — requiring minimal supervision from an analyst for successful execution, robust — capable of handling instantaneous bifurcations and end-of-stroke conditions, and numerically efficient — through the application of numerical reduction strategies, custom sparse matrix methods and vectorization.

In the first primary section, the focus is on automatic, graph-theoretic methods for setting up a mechanism's constraint equations and solving the dynamic equations of motion. A multibody system's constraint equations, i.e. the Jacobian matrix, plays a central role in the equations of motion, and is almost never full-rank, which complicates the solution process even for relatively simple systems. Therefore, Generalized Coordinate Partitioning (GCP), a numerical method based on LU decomposition applied to the Jacobian matrix is applied to find the optimal set of independent, generalized coordinates to describe the system. To increase the efficiency of the GCP algorithm, a new general purpose graph-partitioning algorithm, referred to as "Kinematic Substructuring" is introduced and numerical results are provided. Furthermore, a new numerical implementation of solving the equations of motion, referred to as the "Preconditioned Spatial Equations of Motion" is presented and new sparse matrix solver is described and demonstrated in several numerical examples.

In the second primary section, it is shown how a simple numerical procedure applied to a mechanism's constraint equations can be used as a measure of transmission performance. The metric, referred to as "mobility numbers" provides an indication of a joint's ability to affect a change on a mechanism's overall configuration and is directly related to a mechanism's instantaneous mobility. The relationship between mobility, transmission and manipulability is discussed. Unlike many other measures of transmission performance, mobility numbers are normalized and bound between 0 and 1, and can be computed simply and efficiently from the Jacobian matrix using LU and QR matrix decomposition methods. Examples of applications of mobility numbers are provided.

Finally, in the last section, aspects of software design, including external and internal storage formats and memoization programming methods are discussed.

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Taft, William T. (William Theodore). "Z-source circuit breakers in naval power systems." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122611.

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Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019
Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 97-100).
New power system components and control systems are required to facilitate the U.S. Navy's move to medium voltage direct current power (MVDC) systems on future vessels. Integrating the z-source circuit breaker into a "typical" naval MVDC power system requires understanding system dynamics that may cause the circuit breaker to inadvertently energize a circuit through regenerative turn-on of the thyristor. An electrically-scaled model and a simulation model are used to characterize voltage transients that could lead to this false triggering. The results of this experiment show that these transients are within the specifications of commercially available components. Limitations in the circuit breaker's protective capabilities during turn-on transients are identified and discussed. Potential topology modifications, control schemes, and power system arrangements that provide protection across the operating range are proposed for further investigation.
by William T. Taft.
Nav. E.
S.M.
Nav.E. Massachusetts Institute of Technology, Department of Mechanical Engineering
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

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Jacobs, Gregory. "Simulation, Control Design, and Experiments on Single and Double Inverted Pendulum Systems." Thesis, Southern Illinois University at Edwardsville, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10010746.

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The discipline of control engineering has been applied for thousands of years. As long as humans have needed a system to vary automatically, different devices, electronics and algorithms have been designed to attain system control and stability. This study intends on implementing the theory developed my mathematicians such as Henri Poincaré, Aleksandr Lyapunov, Rudolf E. Kálmán and many others in an attempt to stabilize an unstable system: a cart and inverted pendulum. In order to stabilize the inverted pendulum system, control designs consisting of both classical and modern approaches will be explored to design effective PID and LQR controllers. Furthermore, an adaptive controller will be designed as well for a one-degree-of-freedom unstable system. For accurate control design, linear and non-linear system identification techniques will be used to attain mathematical dynamic system models. Multiple tuning techniques will be utilized to achieve the most stable system possible. A micro-processor (Arduino) will be used in conjunction with a computer for data communication and digital control algorithms. The utilization of an Arduino will require the design and implementation of digital control systems, digital tuning techniques, and digital filtering. If successful, the implemented theory will result in the stabilization of a multiple degree of freedom system with chaotic potential.

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Zuo, Lei 1974. "Optimal control with structure constraints and its application to the design of passive mechanical systems." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/68378.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.
Page 214 blank.
Includes bibliographical references.
Structured control (static output feedback, reduced-order control, and decentralized feedback) is one of the most important open problems in control theory and practice. In this thesis, various techniques for synthesis of structured controllers are surveyed and investigated, including H2 optimization, H[infinity] optimization, L1 control, eigenvalue and eigenstructure treatment, and multiobjective control. Unstructured control-full- state feedback and full-order control-is also discussed. Riccati-based synthesis, linear matrix inequalities (LMI), homotopy methods, gradient- and subgradientbased optimization are used. Some new algorithms and extensions are proposed, such as a subgradient-based method to maximize the minimal damping with structured feedback, a multiplier method for structured optimal H2 control with pole regional placement, and the LMI-based H2/H[infinity]/pole suboptimal synthesis with static output feedback. Recent advances in related areas are comprehensively surveyed and future research directions are suggested. In this thesis we cast the parameter optimization of passive mechanical systems as a decentralized control problem in state space, so that we can apply various decentralized control techniques to the parameter design which might be very hard traditionally. More practical constraints for mechanical system design are considered; for example, the parameters are restricted to be nonnegative, symmetric, or within some physically-achievable ranges. Marginally statable systems and hysterically damped systems are also discussed. Numerical examples and experimental results are given to illustrate the successful application of decentralized control techniques to the design of passive mechanical systems, such as multi-degree-of-freedom tuned-mass dampers, passive vehicle suspensions, and others.
by Lei Zuo.
S.M.

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Eubanks, Charles Frederick. "A Framework for computer-based failure modes and effects analysis of mechanical systems in the conceptual design phase /." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu148794150429435.

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Gupta, Raj K. Ph D. 1969. "Electrostatic pull-in test structure design for in-situ mechanical property measurements of microelectromechanical systems (MEMS)." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10454.

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Austin, Andrew. "Process Capability in a Computer Integrated Manufacturing Cell." TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1322.

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With the rise of automation in traditional manufacturing processes, more companies are beginning to integrate computer integrated manufacturing (CIM) cells on their production floors. Through CIM cell integration, companies have the ability to reduce process time and increase production. One of the problems created with CIM cell automation is caused by the dependency the sequential steps have on one another. Dependency created by the previous step increases the probability that a process error could occur due to previous variation. One way to eliminate this dependency is through the use of an in-process measuring device such as a Renishaw spindle probe used in conjunction with a computer numerical control (CNC) milling machine. Western Kentucky University (WKU) utilizes a CIM cell in the Senator Mitch McConnell Advanced Manufacturing and Robotics laboratory. The laboratory is located in the Architectural and Manufacturing Sciences department and gives students the opportunity to learn how automated systems can be integrated. The CIM cell consists of three Mitsubishi six-axis robots, a Haas Mini-mill, a Haas GT-10 lathe, an AXYZ, Inc. CNC router table, 120 watt laser engraver, an Automated Storage and Retrieval System (ASRS), material handling conveyor, and vision station. The CIM cell functions throughout the curriculum as a means for applied learning and research. The researcher used this CIM cell in order to determine if an in-process measuring device, such as the Renishaw spindle probe, had the ability to affect process capability. The researcher conducted the study to see if an in-process measuring device can be integrated into the CIM cell located in the Senator Mitch McConnell Advanced Manufacturing and Robotics laboratory to eliminate compounding variation. The researcher discovered that through the use of a Renishaw 40-2 spindle probe used in conjunction with a CNC Haas Mini Mill, process capability has the potential to be improved in a CIM cell by accounting for compounding variation present in the process.

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Soni, Ravi. "Computer-aided modeling and simulation of molecular systems and protein secondary structure prediction." Ohio : Ohio University, 1993. http://www.ohiolink.edu/etd/view.cgi?ohiou1176235817.

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Han, Sijing. "Design and Modeling Environment for Nano-Electro-Mechanical Switch (NEMS) Digital Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1354568246.

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Baker, Tyson J. "Attribution Standardization for Integrated Concurrent Engineering." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd873.pdf.

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Le, Toan T. "A Single-Stage Passive Vibration Isolation System for Scanning Tunneling Microscopy." DigitalCommons@CalPoly, 2021. https://digitalcommons.calpoly.edu/theses/2272.

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Scanning Tunneling Microscopy (STM) uses quantum tunneling effect to study the surfaces of materials on an atomic scale. Since the probe of the microscope is on the order of nanometers away from the surface, the device is prone to noises due to vibrations from the surroundings. To minimize the random noises and floor vibrations, passive vibration isolation is a commonly used technique due to its low cost and simpler design compared to active vibration isolation, especially when the entire vibration isolation system (VIS) stays inside an Ultra High Vacuum (UHV) environment. This research aims to analyze and build a single-stage passive VIS for an STM. The VIS consists of a mass-spring system staying inside an aluminum hollow tube. The mass-spring system is comprised of a circular copper stage suspended by a combination of six extension springs, and the STM stays on top of the copper stage. Magnetic damping with neodymium magnets, which induces eddy currents in the copper conductor, is the primary damping method to reduce the vibrations transferred to the mass-spring system. FEMM and MATLAB® are used to model magnetic flux density and damping coefficients from eddy current effect, which will help determine the necessary damping ratios for the VIS. Viton, which demonstrates a high compatibility with vacuum environments, will also serve as a great damping material between joints and contacts for the housing tube. Viton will be modeled as a Mooney-Rivlin hyperelastic material whose material parameters are previous studied, and Abaqus will be used as a Finite Element Analysis software to study the Viton gaskets’ natural frequencies. The natural frequencies of the aluminum hollow tube will also be investigated through Abaqus.

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Mensah, Edoe F. Kwatny Harry G. "Logic-based optimal control for shipboard power system management /." Philadelphia, Pa. : Drexel University, 2008. http://hdl.handle.net/1860/2765.

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29

Goolcharan, John D. "Computational Fluid Dynamic analysis of Microbubble Drag Reduction Systems at High Reynolds Number." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2542.

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Microbubble drag reduction (MBDR) is an effective method to improve the efficiency of fluid systems. MBDR is a field that has been extensively studied in the past, and experimental values of up to 80% to 90% drag reduction have been obtained. The effectiveness and simplicity of MBDR makes it a viable method for real world applications, particularly in naval applications where it can reduce the drag between the surface of ships and the surrounding water. A two dimensional single phase model was created in ANSYS Fluent to effectively model the behavior of bubble laden flow over a flat plate. This model was used to analyze the effectiveness of MBDR based on the following factors: Reynolds number, types of gas injected, upstream flow velocity, upstream fluid type, density ratio, flow rate of injected gas, using air as the upstream injected fluid.

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30

Conradie, Antonie Eduard. "Performance optimization of engineering systems with particular reference to dry-cooled power plants." Thesis, Link to the online version, 1995. http://hdl.handle.net/10019.1/1326.

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31

Huang, Zheng. "Computer-aided modeling and simulation of molecular systems and protein (WT-bGH) structure minimization." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179347691.

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Hu, Zhen Hua Sampson. "Antennas with frequency domain control for future communication systems." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3332/.

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This dissertation describes research into “Antennas with Frequency Domain Control for Future Communication Systems” and several novel antennas are shown, each of which addresses a specific issue for current and future communication systems, in terms of wideband coverage, channel capacity, antenna isolation and band-rejection. These antenna designs may be candidates for implementation in future multiband radios, and software defined radio (SDR) and cognitive radio (CR) systems, which are two new concepts in wireless communications in the foreseeable future, although it is evident that there are as yet no clear specifications for those future systems. A novel two-port reconfigurable antenna which can operate within a narrowband or wideband mode is presented. Three different structures of wideband reconfigurable balanced antennas, with a wide tuning range, have been proposed. When the balanced antenna is combined with the two-port chassis antenna, it becomes a reconfigurable MIMO antenna for small terminals and at least 15 dB of isolation is achieved. Several designs of conical monopole antennas, incorporating different types of slots to achieve good band-rejection behaviour, have been introduced. These are the 2 Cshaped, 4 C-shaped slots, 4 U-shaped slots, 4 tilted-U-shaped slots and 4 U-C-shaped slots. The study of wideband antennas with notched-band behaviour using a simple equivalent circuit model has been proposed. It has been noted that increasing the number of resonators and the coupling factor will increase the band-rejection. However, it will also widen the bandwidth of the frequency notched band. A novel pyramidal monopole antenna, with four loop shaped slots, offering wide tunable band-notch, is also presented.

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Roberts, David Anthony. "Discontinuous Systems Analysis: an Interdisciplinary Analysis Tool." Oxford, Ohio : Miami University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1196390609.

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Vij, Lokesh. "Computer aided modeling of proteins and prediction of their 3-D structure using neural networks." Ohio : Ohio University, 1993. http://www.ohiolink.edu/etd/view.cgi?ohiou1176312284.

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Poorkiany, Morteza. "Managing design rationale in the development of product families and related design automation systems." Doctoral thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Produktutveckling, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-38033.

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As the markets’ needs change rapidly, developing a variety of products that meet customers’ diverse needs is a competitive factor for many manufacturing companies. Development of highly customized products requires following an engineer-to-order business process to allow the products to be modified or adapted to new customers’ specifications, which brings more value to the customer and profit to the company. The design of a new product variant involves a large amount of repetitive and time-consuming tasks but also information handling activities that are sometimes beyond human capabilities. Such work that does not rely so much on creativity can be carried out more efficiently by applying design automation systems. Design automation stands out as an effective means of cutting costs and lead time for a range of well-defined design activities and is mainly considered as a computer-based tool that processes and manipulates the design information. Variant design usually concern generating a new variant of a basic design, that has been developed and proved previously, according to new customer’s demands. To efficiently generate a new variant, a deep understanding of the intention and fundamentals of the design is essential and can be achieved through access to design rationale—the explanation of the reasons and justifications behind the design. The maintenance of product families and their corresponding design automation systems is essential to retaining their usefulness over time and adapting them to new circumstances. Examples of new circumstances can include the introduction of new variants of existing products, changes in design rules to meet new standards or legislations, or changes in technology. To maintain a design automation system, updating the design knowledge (e.g. design rules) is required. The use of design rationale will normally become a necessity for allowing a better understanding of the knowledge. Consequently, there is a need for principles and methods that enable the capture and structure of the design rationale and sharing them with the users. This study presents methods and tools for modeling design knowledge and managing design rationale in order to support the utilization and maintenance of design automation systems. Managing design rationale concerns enabling the capturing, structuring, and sharing of design rationale. The results have been evaluated through design automation systems in two case companies.
Att kunna erbjuda kundanpassade produkter har blivit allt viktigare för många tillverkande företag. Utformningen av en ny produktvariant involverar en stor mängd repetitiva och tidskrävande uppgifter men även informationshanteringsaktiviteter som ibland är bortom mänskliga möjligheter. Sådant arbete som inte förlitar sig så mycket på kreativitet kan genomföras mer effektivt genom att använda designautomatiseringssystem. Designautomatisering framstår som ett effektivt sätt att minska kostnader och ledtid för en rad väldefinierade designaktiviteter och betraktas huvudsakligen som ett datorbaserat verktyg som analyserar och syntetiserar designinformationen. Variantdesign handlar vanligtvis om att skapa en ny variant av en grundläggande design, som har utvecklats och bevisats tidigare enligt nya kunders krav. För att effektivt skapa en ny variant är en djup förståelse för designens avsikt och grundläggande uppbyggnad avgörande och kan uppnås genom tillgång till ”design rationale”- förklaringen av skälen och motiveringarna bakom designen. Underhållet av produktfamiljer och deras motsvarande designautomatiseringssystem är viktigt för att behålla användbarheten över tid och anpassa dem till nya omständigheter. Exempel på nya omständigheter kan innefatta införande av nya varianter av befintliga produkter, ändringar av designregler för att uppfylla nya standarder, lagstiftningar eller tekniska ändringar. För att upprätthålla ett designautomatiseringssystem krävs uppdatering av designkunskapen (t ex designregler). Användningen av design rationale kommer normalt att bli en nödvändighet för att ge en bättre förståelse av kunskapen. Följaktligen finns det ett behov av principer och metoder som möjliggör fångande och strukturering av design rationale och dela dem med användarna. Denna studie presenterar metoder och verktyg för modellering av designkunskap och hantering av design rationale för att stödja utnyttjande och underhåll av designautomatiseringssystem. Vid hantering av design rationale gäller det att göra det möjligt att fånga, strukturera och dela med sig av design rationale. Resultaten har utvärderats genom att undersöka effekterna av dem i designautomationssystem i två företag.

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36

Schuster, Michael Jeremy. "PHYSICAL TESTING OF POTENTIAL FOOTBALL HELMET DESIGN ENHANCEMENTS." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1596.

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Football is a much loved sport in the United States. Unfortunately, it is also hard on the players and puts them at very high risk of concussion. To combat this an inventor in Santa Barbara brought a new design to Cal Poly to be tested. The design was tested in small scale first in order to make some preliminary conclusions about the design. In order to fully test the helmet design; however, full scale testing was required. In order to carry out this testing a drop tower was built based on National Operating Committee on Standards for Athletic Equipment, NOCSAE, specification. The drop tower designed for Cal Poly is a lower cost and highly portable version of the standard NOCSAE design. Using this drop tower and a 3D printed prototype the new design was tested in full scale.

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Avila, Gomez Adrian Enrique. "Development MEMS Acoustic Emission Sensors." Scholar Commons, 2017. https://scholarcommons.usf.edu/etd/7392.

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The purpose of this research is to develop MEMS based acoustic emission sensors for structural health monitoring. Acoustic emission (AE) is a well-established nondestructive testing technique that is typically used to monitor for fatigue cracks in structures, leaks in pressurized systems, damages in composite materials or impacts. This technology can offer a precise evaluation of structural conditions and allow identification of imminent failures or minor failures that can be addressed by planned maintenances routines. AE causes a burst of ultrasonic energy that is measured as high frequency surface vibrations (30 kHz to 1 MHz) generated by transient elastic waves that are typically emitted from growing cracks at the interior of the structure. The AE sensor marketplace is currently dominated by bulky and expensive piezoelectric transducers that are wired to massive multichannel data acquisition systems. These systems are complex to operate with the need of signal conditioning units and near proximity pre-amplifiers for each sensor that demands a fairly complicated wiring requirements. Furthermore, due to the high prices of conventional AE sensors and associated instrumentation, and the current requirements in sensor volumes for smart transportation infrastructure, it is undeniable that new AE technology is required for affordable structural health monitoring. The new AE technology must deliver comparable performance at one or two orders of magnitude lower cost, size and weight. MEMS acoustic emission (AE) sensors technology has the potential to resolve several of these traditional sensor’s shortcomings with the advantage of possible integration of on-chip preamplifier while allowing substantially cost reduction due to the batch processing nature of MEMS technology. This study will focus on filling some of the major existing gaps between current developments in MEMS acoustic emission sensors and commercial piezoelectric sensors, such as sensor size, signal-to-noise ratio (SNR), cost and the possibility to conform to sharply curved surfaces. Basically, it is proposed to develop a new class of micro-machined AE sensors or sensor arrays through strategic design of capacitive and piezoelectric MEMS sensors, which will focus on optimizing the following performance aspects: Creating geometric designs to manipulate the sensor resonant frequency and to optimize Q factor under atmospheric pressure and ambient environment. Developing a strategic selection of materials according to its acoustic impedance as insulator, structure and backing material. Developing strategies to improve the signal to noise ratio SNR with and without integrated amplification/signal processing. Performing a comparison between MEMS and commercial piezoelectric sensors.

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38

Begley, Taylor A. "REDUCED FREQUENCY MOTOR STARTING FOR THIRD WORLD POWER SYSTEMS." UKnowledge, 2009. http://uknowledge.uky.edu/gradschool_theses/607.

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People in modern industrialized societies live a blessed life relative to those who do not when it comes to some modern conveniences. While many think nothing of flipping on a light switch or running electric appliances, there are people in third world countries could not imagine such things. As service projects are being undertaken to bring such conveniences to those less fortunate, there often is the harsh reality of a strict budget. An item that commands a large portion of said budget is often the diesel generator used to provide the facility with electricity. Generators serving motor loads are typically oversized due to a large kVA starting requirement. This paper addresses an approach to this problem by temporarily restricting the generator fuel supply by pulling back the rack of the mechanical governor reducing the frequency and voltage output as a motor load is switched onto the system. By reducing the voltage and frequency output of the generator, the motor is switched on at a time when its typically poor power factor and resulting kVA requirement is mitigated by the lower voltage and frequency allowing for a smaller generator to be used.

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39

Simon, Derek. "Static Balancing of the Cal Poly Wind Turbine Rotor." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/837.

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The balancing of a wind turbine rotor is a crucial step affecting the machine’s performance, reliability, and safety, as it directly impacts the dynamic loads on the entire structure. A rotor can be balanced either statically or dynamically. A method of rotor balancing was developed that achieves both the simplicity of static balancing and the accuracy of dynamic balancing. This method is best suited, but not limited, to hollow composite blades of any size. The method starts by quantifying the mass and center of gravity of each blade. A dynamic calculation is performed to determine the theoretical shaking force on the rotor shaft at the design operating speed. This force is converted to a net counterbalance mass required for each blade. Despite the most careful methodology, there may still be large errors associated with these measurements and calculations. Therefore, this new method includes a physical verification of each blade’s individual balance against all other blades on the rotor, with the ability to quantify the discrepancy between blades, and make all balance adjustments in situ. The balance weights are aluminum plugs of varying lengths inserted into the root of each blade with a threaded steel rod running through the middle. The balance adjustment is thus not visible from outside. The weight of the plug and rod represent the coarse counterbalance of each blade, based on the dynamic calculations. The threaded steel rod acts as a fine adjustment on the blades’ mass moment when traveled along the plug. A dedicated blade-balance apparatus, designed and constructed in-house, is used to verify and fine-tune each individual blade and compare it to all other blades on the rotor. The resulting blade assembly is verified on a full rotor static balancing apparatus. The full rotor apparatus measures the steady state tilt of the rotor when balanced on a point. Next, the rotors' tilt is related to its overall level of imbalance with quantifiable error. Most error comes from the fact that the hub, comparable in mass to the blades, creates a false righting moment of the assembly not present in operation. The fully assembled rotor is tested, pre and post balance, in operation on the turbine at a series of predetermined speeds. This is accomplished with a 3-axis accelerometer mounted on the main turbine shaft bearing and a control system which regulates and records turbine speed at 100 Hz

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40

Sommer, Andrew Patrick. "VIBRATION-BASED HEALTH MONITORING OF MULTIPLE-STAGE GEAR TRAIN AND DIFFERENTIAL PLANETARY TRANSMISSION INVOLVING TEETH DAMAGE AND BACKLASH NONLINEARITY." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/631.

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The objective of this thesis is to develop vibration-based fault detection strategies for on-line condition monitoring of gear transmission systems. The study divides the thesis into three sections. First of all, the local stresses created by a root fatigue crack on a pinion spur gear are analyzed using a quasi-static finite element model and non-linear contact mechanics simulation. Backlash between gear teeth which is essential to provide better lubrication on tooth surfaces and to eliminate interference is included as a defect and a necessary part of transmission design. The second section is dedicated to fixed axis power trains. Torsional vibration is shown to cause teeth separation and double-sided impacts in unloaded and lightly loaded gearing drives. The transient and steady-state dynamic loading on teeth within a two stage crank-slider mechanism arising from backlash and geometric manufacturing errors is investigated by utilizing a non-linear multi-body dynamics software model. The multi-body model drastically reduces the computation time required by finite element methods to simulate realistic operation. The gears are considered rigid with elastic contact surfaces defined by a penalty based non-linear contact formulation. The third section examines a practical differential planetary transmission which combines two inputs and one output. Planetary gears with only backlash errors are compared to those containing both backlash and tooth defects under different kinematic and loading conditions. Fast Fourier Transform (FFT) analysis shows the appearance of side band modulations and harmonics of the gear mesh frequency. A joint time-frequency analysis (JTFA) during start-up reveals the unique vibration patterns for fixed axis gear train and differential planetary gear, respectively, when the contact forces increase during acceleration.

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41

Jayakumar, Adithya. "Simulation-based optimization of Hybrid Systems Using Derivative Free Optimization Techniques." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1531954151797307.

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42

Poorkiany, Morteza. "Support Maintenance of Design Automation Systems - A Framework to Capture, Structure and Access Design Rationale." Licentiate thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH. Forskningsmiljö Produktutveckling - Datorstödd konstruktion, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-28172.

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The ability to innovate and launch customized products that are well matched to customer demands is a competitive factor for many manufacturing companies. Development of highly customized products requires following an engineer-to-order business process to allow the products to be modified or adapted to new customers’ specifications, which brings more value to the customer and profit to the company. Design of a new product variant involves a large amount of repetitive and time consuming tasks but also information handling activities that are sometimes beyond human capabilities. Such work that does not rely so much on creativity can be carried out more efficiently by applying design automation systems. Design automation stands out as an effective means of cutting costs and lead time for a range of well-defined design activities and is mainly considered as a computer-based tool that processes and manipulates the design information. Adaptation and variant design usually concern generating a new variant of a basic design, which has been developed and proved previously, according to new customer’s demands. In order to efficiently generate a new variant, a deep understanding of the previous design is essential. Such understanding can be achieved by access to the design rationale explaining the reasons and justifications behind the design. Maintenance of design automation systems is essential to retain their usefulness over time and adapt them to new circumstances. New circumstances are, for example, introduction of new variants of existing products, changes in design rules in order to meet new standards or legislations, or changes in technology. To maintain a design automation system, updating the design knowledge (e.g. design rules) is required. Use of design rationale will normally become a necessity to allow a better understanding of the knowledge. Consequently, there is a need of principles and methods to enable capture, structure, and access design rationale. In this study, a framework for modeling design knowledge and managing design rationale in order to support maintenance of design automation systems is presented. Managing of design rationale concerns enabling capture, structure, and access to design rationale. In order to evaluate the applicability of the framework, the findings are tested through design automation systems in two case companies.
Impact
Adapt

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43

Sholapurwalla, Ardeshir. "Two-dimension to three-dimension conversion using sliced sections." Ohio : Ohio University, 1991. http://www.ohiolink.edu/etd/view.cgi?ohiou1183747718.

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44

Dhamija, Dinesh. "Macintosh - Bridgeport communications CAD/CAM." Ohio : Ohio University, 1988. http://www.ohiolink.edu/etd/view.cgi?ohiou1182784285.

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45

Yung, Melody T. 1976. "Revamping EDICS : the Engineering-Design Instructional Computer System." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/89931.

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46

Salaskar, Swati. "Digital human modeling for ergonomic evaluation of laparoscopic surgery." Diss., Online access via UMI:, 2009.

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47

Samson, Akiev. "Digital human modeling for ergonomic assessment of patient lifting by paramedics." Diss., Online access via UMI:, 2009.

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Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2009.
Includes bibliographical references.

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48

Tzelepis, Vasileios. "Electromechanics of an Ocean Current Turbine." ScholarWorks@UNO, 2015. http://scholarworks.uno.edu/td/2112.

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The development of a numeric simulation for predicting the performance of an Ocean Current Energy Conversion System is presented in this thesis along with a control system development using a PID controller for the achievement of specified rotational velocity set-points. In the beginning, this numeric model is implemented in MATLAB/Simulink® and it is used to predict the performance of a three phase squirrel single-cage type induction motor/generator in two different cases. The first case is a small 3 meter rotor diameter, 20 kW ocean current turbine with fixed pitch blades, and the second case a 20 meter, 720 kW ocean current turbine with variable pitch blades. Furthermore, the second case is also used for the development of a Voltage Source Variable Frequency Drive for the induction motor/generator. Comparison among the Variable Frequency Drive and a simplified model is applied. Finally, the simulation is also used to estimate the average electric power generation from the 720 kW Ocean Current Energy Conversion System which consists of an induction generator and an ocean current turbine connected with a shaft which modeled as a mechanical vibration system.

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Adams, Azeez Olawale. "Control of reconfigurable assembly system." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5368.

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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: This work considers the control of reconfigurable assembly systems using a welding assembly system as a case study. The assembly system consists of a pallet magazine, a feeding system, an inspection and removal system, a welding system and a conveyor. The aim of the work is to compare PC and PLC as controllers, as well as to compare two different approaches to reconfigurable control. The control system of the pallet magazine was developed using a PC and a PLC. The PC control was programmed using Visual C#, while the PLC was programmed in Ladder Logic using Siemens S-300 STEP7. The two controllers were compared based on the attributes that measure the quality of a controller's software, which include its capability, availability, usability and adaptability. The approaches to reconfigurable control considered were the agent-based methodology and the IEC 61499 distributed control methodology, both of which were applied to the feeding system. The agent-based control system was implemented using the JADE agent platform, while the IEC 61499 distributed control system was implemented using the FBDK software kit. These two methods were compared based on the characteristics of a reconfigurable system, which include the system's modularity, integrability, convertibility, diagnosability, customization and scalability. The result obtained in comparing the PC to the PLC shows that the PLC performs better in terms of capability, availability and usability, while the PC performs better in terms of adaptability. Also, the result of the comparison between the agent-based control system and the IEC 61499 distributed control system shows that the agent-based control system performs better in terms of integrability, diagnosability and scalability, while the IEC 61499 distributed control system performs better in terms of modularity and customization. They are, however, on a par in terms of convertibility.
AFRIKAANSE OPSOMMING: Hierdie werk beskou die beheer van herkonfigureerbare monteringstelsels met 'n sweismonteringstelsel as gevallestudie. Die monteringstelsel bestaan uit 'n paletmagasyn, 'n voerstelsel, 'n inspeksie-en- verwyderingstelsel, 'n sweisstelsel en 'n voerband. Die mikpunt van die werk is om persoonlike rekenaars (PCs) en programmeerbare-logikabeheerders (PLCs) as beheerders te vergelyk, asook om twee verskillende benaderings tot herkonfigureerbare beheer te vergelyk. Die beheerstelsel van die paletmagasyn is ontwikkel met 'n PC en 'n PLC. Die PC-beheer is in Visual C# geprogrammeer, terwyl die PLC in leerlogika met Siemens S-300 STEP7 geprogrammeer is. Die twee beheerders is vergelyk in terme van die eienskappe wat die kwaliteit van 'n beheerder se sagteware meet en sluit in vermoë, beskikbaarheid, bruikbaarheid en aanpasbaarheid. Die benaderings tot herkonfigureerbare beheer wat oorweeg is, is die agent-gebaseerde metodologie en die IEC 61499 verspreide-beheermetodologie. Beide is op die voerstelsel toegepas. Die agent-gebaseerde beheerstelsel is geïmplementeer met behulp van die JADE agent-platform, terwyl die IEC 61499 verspreide stelsel geïmplementeer is met behulp van die FBDK sagteware-stel. Hierdie twee metodes se vergelyking is gebaseer op die eienskappe van 'n herkonfigureerbare stelsel, waarby die stelsel se modulariteit, integreerbaarheid, diagnoseerbaarheid, pasmaakbaarheid en skaleerbaarheid ingesluit is. Die resultate wat in die vergelyking tussen die PC en PLC verkry is, toon dat die PLC beter vaar in terme van vermoë, beskikbaarheid en bruikbaarheid, terwyl die PC beter vaar in terme van aanpasbaarheid. Die resultaat van die vergelyking tussen die agent-gebaseerde beheerstelsel en die IEC 61499 verspreide beheerstelsel wys dat die agent-gebaseerde beheerstelsel beter vaar in terme van integreerbaarheid, diagnoseerbaarheid en skaleerbaarheid, terwyl die IEC 61499 verspreide beheerstelsel beter vaar in terme van modulariteit en pasmaakbaarheid. Hulle is egter vergelykbaar in terme van omskepbaarheid.

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50

Fulcher, Jared T. "A DESIGN PATHFINDER WITH MATERIAL CORRELATION POINTS FOR INFLATABLE SYSTEMS." UKnowledge, 2014. http://uknowledge.uky.edu/me_etds/39.

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The incorporation of inflatable structures into aerospace systems can produce significant advantages in stowed volume to mechanical effectiveness and overall weight. Many applications of these ultra-lightweight systems are designed to precisely control internal or external surfaces, or both, to achieve desired performance. The modeling of these structures becomes complex due to the material nonlinearities inherent to the majority of construction materials used in inflatable structures. Furthermore, accurately modeling the response and behavior of the interfacing boundaries that are common to many inflatable systems will lead to better understanding of the entire class of structures. The research presented involved using nonlinear finite element simulations correlated with photogrammetry testing to develop a procedure for defining material properties for commercially available polyurethane-coated woven nylon fabric, which is representative of coated materials that have been proven materials for use in many inflatable systems. Further, the new material model was used to design and develop an inflatable pathfinder system which employs only internal pressure to control an assembly of internal membranes. This canonical inflatable system will be used for exploration and development of general understanding of efficient design methodology and analysis of future systems. Canonical structures are incorporated into the design of the phased pathfinder system to allow for more universal insight. Nonlinear finite element simulations were performed to evaluate the effect of various boundary conditions, loading configurations, and material orientations on the geometric precision of geometries representing typical internal/external surfaces commonly incorporated into inflatable pathfinder system. The response of the inflatable system to possible damage was also studied using nonlinear finite element simulations. Development of a correlated material model for analysis of the inflatable pathfinder system has improved the efficiency of design and analysis techniques of future inflatable structures.

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Dissertations / Theses on the topic 'Mechanical engineering. Computer systems. Mechanics'

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