Dissertations / Theses: 'Mechanical dynamic systems'

1

Davison, Paul. "Dynamic analysis of flexible multibody mechanical systems." Thesis, University of Bath, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261035.

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Tariku, Fitsum. "Simulation of dynamic mechanical systems with stick-slip friction." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0011/MQ38415.pdf.

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Yunt, Mehmet 1975. "Nonsmooth dynamic optimization of systems with varying structure." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/65284.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 357-365).
In this thesis, an open-loop numerical dynamic optimization method for a class of dynamic systems is developed. The structure of the governing equations of the systems under consideration change depending on the values of the states, parameters and the controls. Therefore, these systems are called systems with varying structure. Such systems occur frequently in the models of electric and hydraulic circuits, chemical processes, biological networks and machinery. As a result, the determination of parameters and controls resulting in the optimal performance of these systems has been an important research topic. Unlike dynamic optimization problems where the structure of the underlying system is constant, the dynamic optimization of systems with varying structure requires the determination of the optimal evolution of the system structure in time in addition to optimal parameters and controls. The underlying varying structure results in nonsmooth and discontinuous optimization problems. The nonsmooth single shooting method introduced in this thesis uses concepts from nonsmooth analysis and nonsmooth optimization to solve dynamic optimization problems involving systems with varying structure whose dynamics can be described by locally Lipschitz continuous ordinary or differential-algebraic equations. The method converts the infinitedimensional dynamic optimization problem into an nonlinear program by parameterizing the controls. Unlike the state of the art, the method does not enumerate possible structures explicitly in the optimization and it does not depend on the discretization of the dynamics. Instead, it uses a special integration algorithm to compute state trajectories and derivative information. As a result, the method produces more accurate solutions to problems where the underlying dynamics is highly nonlinear and/or stiff for less effort than the state of the art. The thesis develops substitutes for the gradient and the Jacobian of a function in case these quantities do not exist. These substitutes are set-valued maps and an elements of these maps need to be computed for optimization purposes. Differential equations are derived whose solutions furnish the necessary elements. These differential equations have discontinuities in time. A numerical method for their solution is proposed based on state event location algorithms that detects these discontinuities. Necessary conditions of optimality for nonlinear programs are derived using these substitutes and it is shown that nonsmooth optimization methods called bundle methods can be used to obtain solutions satisfying these necessary conditions. Case studies compare the method to the state of the art and investigate its complexity empirically.
by Mehmet Yunt.
Ph.D.

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Orbak, Âli Yurdun 1970. "Identification and self-tuning control of dynamic systems." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/35457.

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Ding, Huali. "Dynamic wear models for gear systems." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1194025602.

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Ospanov, Asset. "DELAY DIFFERENTIAL EQUATIONS AND THEIR APPLICATION TO MICRO ELECTRO MECHANICAL SYSTEMS." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5674.

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Delay differential equations have a wide range of applications in engineering. This work is devoted to the analysis of delay Duffing equation, which plays a crucial role in modeling performance on demand Micro Electro Mechanical Systems (MEMS). We start with the stability analysis of a linear delay model. We also show that in certain cases the delay model can be efficiently approximated with a much simpler model without delay. We proceed with the analysis of a non-linear Duffing equation. This model is a significantly more complex mathematical model. For instance, the existence of a periodic solution for this equation is a highly nontrivial question, which was established by Struwe. The main result of this work is to establish the existence of a periodic solution to delay Duffing equation. The paper claimed to establish the existence of such solutions, however their argument is wrong. In this work we establish the existence of a periodic solution under the assumption that the delay is sufficiently small.

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Shi, Zhenghong. "Nonlinear Time-varying Dynamic Modeling of Vehicle Driveline Systems with Emphasis on Hypoid Gear Excitation and Response." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1490355055106922.

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8

Moody, Seth S. "Development of Dynamic Thermal Performance Metrics For Eco-roof Systems." Thesis, Portland State University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1535587.

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In order to obtain credit for an eco-roof in building energy load calculations the steady state and time-varying thermal properties (thermal mass with evapotranspiration) must be fully understood. The following study presents results of experimentation and modeling in an effort to develop dynamic thermal mass performance metrics for eco-roof systems. The work is focused on understanding the thermal parameters (foliage & soil) of an eco-roof, further validation of the EnergyPlus Green Roof Module and development of a standardized metric for assessing the time-varying thermal benefits of eco-roof systems that can be applied across building types and climate zones.

Eco-roof foliage, soil and weather parameters were continuously collected at the Green Roof Integrated PhotoVoltaic (GRIPV) project from 01/20/2011 to 08/28/2011. The parameters were used to develop an EnergyPlus eco-roof validation model. The validated eco-roof model was then used to estimate the Dynamic Benefit for Massive System (DBMS) in 4 climate-locations: Portland Oregon, Chicago Illinois, Atlanta Georgia and Houston Texas.

GRIPV30 (GRIPV soil with 30% soil organic matter) was compared to 12 previously tested eco-roof soils. GRIPV30 reduced dry soil conductivity by 50%, increased field capacity by 21% and reduced dry soil mass per unit volume by 60%. GRIPV30 soil had low conductivity at all moisture contents and high heat capacity at moderate and high moisture content. The characteristics of the GRIPV30 soil make it a good choice for moisture retention and reduction of heat flux, improved thermal mass (heat storage) when integrating an eco-roof with a building.

Eco-roof model validation was performed with constant seasonal moisture driven soil properties and resulted in acceptable measured - modeled eco-roof temperature validation. LAI has a large impact on how the Green Roof Module calculates the eco-roof energy balance with a higher impact on daytime (measured - modeled) soil temperature differential and most significant during summer.

DBMS modeling found the mild climates of Atlanta Georgia and Houston Texas with eco-roof annual DBMS of 1.03, 3% performance improvement above the standard building, based on cooling, heating and fan energy consumption. The Chicago Illinois climate with severe winter and mild spring/summer/fall has an annual DBMS of 1.01. The moderate Portland Oregon climate has a below standard DBMS of 0.97.

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Tubilla, Kuri Fernando. "Dynamic scheduling of manufacturing systems with setups and random disruptions." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67606.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 249-256).
Manufacturing systems are often composed of machines that can produce a variety of items but that most undergo time-consuming (and possibly costly) setups when switching between product types. Scheduling these setups efficiently can have important economic effects on the performance of the plant and involves a tradeoff between throughput, inventory, and operating costs. In addition, the schedule must be robust to random disruptions such as failures or raw material shortages, which are common in production environments. In this thesis, we study policies that address the setup scheduling problem dynamically, in response to current conditions in the system. A new heuristic, called the Hedging Zone Policy (HZP), is introduced and developed. It is a dynamic-sequence policy that always produces the current part type at its maximum production rate until a fixed base stock level is reached. Then, before switching setups, the policy might produce the current part type at its demand rate for some additional time. When selecting changeovers, the HZP implements two types of decision rules. If the difference between base stock and surplus level is small for all part types, the item with the largest weighted difference is selected. Otherwise, the policy uses a fixed priority ranking to select between items that are far from their base stock value. In order to demonstrate the benefits of our policy, we also adapt and implement several other heuristics that have been proposed in the literature for related models. The policies are first analyzed in a purely deterministic setting. The stability of the HZP is addressed and it is shown that a poor selection of its parameters leads to a condition in which some low-priority parts are ignored, resulting in an unstable system. Using Lyapunov's direct method, we obtain an easy-to-evaluate and not-too-conservative condition that ensures production of all part types with bounded surplus. We then compare, through a series of extensive numerical experiments with three-part-type systems, the deterministic performance of the policies in both make-to-order and make-to-stock settings. We show that the HZP outperforms other policies within its class in both cases, a fact that is mainly attributed to its priority-based decisions. When compared to the approximate optimal cost of the problem, our policy performs very well in the make-to-order case, while the simplicity of its base stock structure makes it less competitive in the deterministic make-to-stock problem. The results are then leveraged for the study of a stochastic model, where we consider the effect of random disruptions in the form of machine failures. We prove that our model converges to a fluid limit under an appropriate scaling. This fact allows us to employ our deterministic stability conditions to verify the stochastic (rate) stability of the failure-prone system. We also extend our previous numerical experiments by characterizing the performance of the policies in the stochastic setting. The results show that the HZP still outperforms other policies in the same class. Furthermore, we find that except for cases where failures occur much less or much more frequently than changeovers, the HZP outperforms a fixed-sequence policy that is designed to track a pre-determined, near-optimal deterministic schedule.
by Fernando Tubilla.
Ph.D.

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Lee, Sungho Ph D. Massachusetts Institute of Technology. "Dynamic response analysis of spar buoy floating wind turbine systems." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/46545.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.
Includes bibliographical references (leaves 83-84).
The importance of alternative energy development has been dramatically increased by the dwindling supplies of oil and gas, and our growing efforts to protect our environment. A variety of meaningful steps have been taken in order to come up with cleaner, healthier and more affordable energy alternatives. Wind energy is one of the most reliable energy alternatives for countries that have sufficiently large wind sources. Due to the presence of steady and strong winds, and the distance from coastline residential, the offshore wind farm has become highly attractive as an ideal energy crisis solution. Floating wind turbine systems are being considered as a key solution to make the offshore wind farm feasible from an economic viewpoint, and viable as an energy resource. This paper presents the design of a synthetic mooring system for spar buoy floating wind turbines functioning in shallow water depths. Nacelle acceleration, static and dynamic tensions on catenaries, the maximum tension acting on the anchors are considered as design performances, and a stochastic analysis method has been used to evaluate those quantities based on sea state spectral density functions. The performance at a 100-year hurricane condition is being defined as a limiting case, and a linear wave theory has been the most fundamental theory applied for the present analysis.
by Sungho Lee.
S.M.

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11

McCarragher, Brenan Joseph. "A discrete event dynamic systems approach to robotic assembly tasks." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/12887.

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12

Huang, Shih-Ying. "Structural analysis from system configurations for modeling and design of multi-energy domain dynamic systems." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42659.

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Kazerooni, H. (Homayoon). "A robust design method for impedance control of constrained dynamic systems." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15218.

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Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1985.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Bibliography: leaves 133-138.
by Homayoon Kazerooni.
Sc.D.

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14

Claewplodtook, Pana. "Optimization of nonlinear dynamic systems without Lagrange multipliers." Ohio : Ohio University, 1996. http://www.ohiolink.edu/etd/view.cgi?ohiou1178654973.

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15

Yang, Shanhu. "An Adaptive Prognostic Methodology and System Framework for Engineering Systems under Dynamic Working Regimes." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1455209450.

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16

Cho, Hee Jin. "DYNAMIC SIMULATION AND OPTIMAL REAL-TIME OPERATION OF CHP SYSTEMS FOR BUILDINGS." MSSTATE, 2009. http://sun.library.msstate.edu/ETD-db/theses/available/etd-03312009-144452/.

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Combined Cooling, Heating, and Power (CHP) systems have been widely recognized as a key alternative for electric and thermal energy generation because of their outstanding energy efficiency, reduced environmental emissions, and relative independence from centralized power grids. The systems provide simultaneous onsite or near-site electric and thermal energy generation in a single, integrated package. As CHP becomes increasingly popular worldwide and its total capacity increases rapidly, the research on the topics of CHP performance assessment, design, and operational strategy become increasingly important. Following this trend of research activities to improve energy efficiency, environmental emissions, and operational cost, this dissertation focuses on the following aspects: (a) performance evaluation of a CHP system using a transient simulation model; (b) development of a dynamic simulation model of a power generation unit that can be effectively used in transient simulations of CHP systems; (c) investigation of real-time operation of CHP systems based on optimization with respect to operational cost, primary energy consumption, and carbon dioxide emissions; and (d) development of optimal supervisory feed-forward control that can provide realistic real-time operation of CHP systems with electric and thermal energy storages using short-term weather forecasting. The results from a transient simulation of a CHP system show that technical and economical performance can be readily evaluated using the transient model and that the design, component selection, and control of a CHP system can be improved using this model. The results from the case studies using optimal real-time operation strategies demonstrate that CHP systems with an energy dispatch algorithm have the potential to yield savings in operational cost, primary energy consumption, and carbon dioxide emissions with respect to a conventional HVAC system. Finally, the results from the case study using a supervisory feed-forward control system illustrate that optimal realistic real-time operation of CHP systems with electric and thermal energy storages can be managed by this optimal control using weather forecasting information.

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Yu, Ssu-Hsin. "Model-based identification and control of nonlinear dynamic systems using neural networks." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/39609.

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Huang, He 1967. "Comparison of neural and control theoretic techniques for nonlinear dynamic systems." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36483.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1994.
Includes bibliographical references (leaves 70-72).
by He Huang.
M.S.

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19

Muratagic, Haris. "Passive Symmetry in Dynamic Systems and Walking." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5998.

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The ubiquitous nature of symmetry lends itself to be taken for granted, however the breath of research on symmetry encompasses several disciplines. In engineering, studies centered on symmetry often address issues in dynamic systems theory, robotics, and gait rehabilitation. This thesis presents findings on two specific topics dealing with passively induced symmetry; dissimilar rotating systems and human gait. Past studies on passive symmetry in dynamic systems often incorporate physical coupling or a controller. This thesis presents a technique to passively induce symmetry between two dissimilar systems that are not physically connected. This work also presents a human gait study consisting of several elements that merge to provide a unique look at how walking symmetry and altered physical parameters (leg length and added weight) of the lower limbs are related. One aspect of this thesis shows the successful development of a general method to induce synchronization between any two dissimilar, uncoupled, rotating systems given the same degrees of freedom, initial angular dynamics, and applied torque. This method is validated with a simulation and subsequent comparison with two physical experiments. The results are in agreement, with slight variations due to the friction and damping of the physical systems. This is further expanded to include the induced symmetry of two systems that experience an external collision. Due to the highly non-linear nature of such systems, an analytical solution was not found; instead a numerical solution is presented that resulted in partial symmetry between systems. The gait study demonstrated that weighted walking and altered leg length have both independent and combined spatio-temporal effects on lower limb symmetry. While altered leg length alone resulted in higher gait asymmetry, the combination of the two physical changes increases this asymmetry to affect the same limb. This study also showed that cognitive and physically distracted walking does not have an added effect to the gait symmetry with passive physical changes. In addition, this study was able to demonstrate that the arm swinging that occurs during natural walking does not significantly alter spatial or temporal gait parameters.

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He, Xiang-Dong. "Dynamic modeling and multivariable control of vapor compression cycles in air conditioning systems." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10725.

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Goupil, Marc Y. "Dynamic Pressure Sensing for the Flight Test Data System." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2115.

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This thesis describes the design, assembly, and test of the FTDS-K, a new device in the Boundary Layer Data System (BLDS) family of flight data acquisition systems. The FTDS-K provides high-frequency, high-gain data acquisition capability for up to two pressure sensors and an additional three low-frequency pressure sensors. Development of the FTDS-K was separated into a core module, specialized analog subsystem, and practical testing of the FTDS-K in a flow measurement mission. The core module combines an nRF52840-based microcontroller module, switching regulator, microSD card, real-time clock, temperature sensor, and trio of pressure sensors to provide the same capabilities as previous-generation BLDS-P devices. An expansion header is included in the core module to allow additional functionality to be added via daughter boards. An analog signal chain comprised of two-stage amplification and fourth-order active antialiasing filters was implemented as a daughter board to provide an AC-coupled end-to-end gain of 7,500 and a DC-coupled end-to-end gain of 50. This arrangement was tested in a wind tunnel to demonstrate that sensors with a full-scale range of 103 kPa can be used to reliably discriminate between laminar and turbulent flows based on pressure fluctuation differences on the order of tens of Pa. A combination of wind-off correction and band-filtering was used to reduce the effect of inherent and induced electrical noise, while two-sensor correlation was tested and shown to be effective at removing certain types of noise. Total power consumption for the FTDS-K in a representative mission is 208 mW, which translates to an operational endurance of 9 hours with 2 AAA LiFeS2 cells at -40°C.

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Migchelbrink, Matthew. "Sliding mode control trajectory tracking implementation on underactuated dynamic systems." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18245.

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Master of Science
Department of Mechanical Engineering
Warren N. White
The subject of linear control is a mature subject that has many proven powerful techniques. Recent research generally falls into the area of non-linear control. A subsection of non-linear control that has garnered a lot of research recently has been in underactuated dynamic systems. Many applications of the subject exist in robotics, aerospace, marine, constrained systems, walking systems, and non-holonomic systems. This thesis proposes a sliding mode control law for the tracking control of an underactuated dynamic system. A candidate Lyapunov function is used to build the desired tracking control. The proposed control method does not require the integration of feedback as does its predecessor. The proposed control can work on a variety of underactuated systems. Its predecessor only worked on those dynamic systems that are simply underactuated (torques acting on some joints, no torques acting on others). For dynamic systems that contain a roll without slip constraint, often a desired trajectory to follow is related to dynamic coordinates through a non-holonomic constraint. A navigational control is shown to work in conjunction with the sliding mode control to allow tracking of these desired trajectories. The methodology is applied through simulations to a holonomic case of the Segbot, an inverted cart-pole, a non-holonomic case of Segbot, and a rolling wheel. The methodology is implemented on an actual Segbot and shown to provide more favorable tracking results than linear feedback gains.

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Martin, Justin N. "Nonlinear tracking of natural mechanical systems for HWIL simulation." Auburn, Ala., 2007. http://repo.lib.auburn.edu/07M%20Theses/MARTIN_JUSTIN_8.pdf.

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Hover, Franz S. "Deeply-towed underwater vehicle systems : a verified analytical procedure for creating parameterized dynamic models." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14005.

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Veeraklaew, Tawiwat. "Optimization of linear time-invariant dynamic systems without lagrange multipliers." Ohio University / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1178821882.

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Thapa, Bal K. "Neural network enhanced self tuning adaptive control application for non-linear control of dynamic systems." Thesis, Aston University, 2001. http://publications.aston.ac.uk/11767/.

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The main theme of research of this project concerns the study of neutral networks to control uncertain and non-linear control systems. This involves the control of continuous time, discrete time, hybrid and stochastic systems with input, state or output constraints by ensuring good performances. A great part of this project is devoted to the opening of frontiers between several mathematical and engineering approaches in order to tackle complex but very common non-linear control problems. The objectives are: 1. Design and develop procedures for neutral network enhanced self-tuning adaptive non-linear control systems; 2. To design, as a general procedure, neural network generalised minimum variance self-tuning controller for non-linear dynamic plants (Integration of neural network mapping with generalised minimum variance self-tuning controller strategies); 3. To develop a software package to evaluate control system performances using Matlab, Simulink and Neural Network toolbox. An adaptive control algorithm utilising a recurrent network as a model of a partial unknown non-linear plant with unmeasurable state is proposed. Appropriately, it appears that structured recurrent neural networks can provide conveniently parameterised dynamic models for many non-linear systems for use in adaptive control. Properties of static neural networks, which enabled successful design of stable adaptive control in the state feedback case, are also identified. A survey of the existing results is presented which puts them in a systematic framework showing their relation to classical self-tuning adaptive control application of neural control to a SISO/MIMO control. Simulation results demonstrate that the self-tuning design methods may be practically applicable to a reasonably large class of unknown linear and non-linear dynamic control systems.

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Axin, Mikael. "Fluid Power Systems for Mobile Applications : with a Focus on Energy Efficiency and Dynamic Characteristics." Licentiate thesis, Linköpings universitet, Fluida och mekatroniska system, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-92578.

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This thesis studies an innovative working hydraulic system design for mobile applications. The purpose is to improve the energy efficiency and the dynamic characteristics compared to load sensing systems without increasing the complexity or adding additional components. The system analysed in this thesis is referred to as flow control. The fundamental difference compared to load sensing systems is that the pump is controlled based on the operator’s command signals rather than feedback signals from the loads. This control approach enables higher energy efficiency since the pressure difference between pump and load is given by the system resistance rather than a prescribed pump pressure margin. High power savings are possible especially at medium flow rates. Furthermore, load sensing systems suffer from poor dynamic characteristics since the pump is operated in a closed loop control mode. This might result in an oscillatory behaviour. Flow control systems have no stability issues attached to the load pressure feedback since there is none. Pressure compensators are key components in flow control systems. This thesis addresses the flow matching problem which occurs when using conventional compensators in combination with a flow controlled pump. Flow sharing pressure compensators solve this problem since the pump flow will be distributed between all active functions. A novel control approach where the directional valve is controlled without affecting the cylinder velocity with the objective of optimizing the damping is proposed. In this research, both theoretical studies and practical implementations demonstrate the capability of flow control systems. Experiments show a reduced pump pressure margin and energy saving possibilities in a short loading cycle for a wheel loader application.

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Noxon, Nikola John Linn. "A MODEL PREDICTIVE CONTROL APPROACH TO ROLL STABILITY OF A SCALED CRASH AVOIDANCE VEHICLE." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/783.

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In this paper, a roll stability controller (RSC) is presented based on an eight degree of freedom dynamic vehicle model. The controller is designed for and tested on a scaled vehicle performing obstacle avoidance maneuvers on a populated test track. A rapidly-exploring random tree (RRT) algorithm is used for the vehicle to execute a trajectory around an obstacle, and examines the geographic, non-homonymic, and dynamic constraints to maneuver around the obstacle. A model predictive controller (MPC) uses information about the vehicle state and, based on a weighted performance measure, generates an optimal trajectory around the obstacle. The RSC uses the standard vehicle state sensors: four wheel mounted encoders, a steering angle sensor, and a six degree of freedom inertial measurement unit (IMU). An emphasis is placed on the mitigation of rollover and spin-out, however if a safe maneuver is not found and a collision is inevitable, the program will run a brake command to reduce the vehicle speed before impact. The trajectory is updated at a rate of 20 Hz, providing improved stability and maneuverability for speeds up to 10 ft/s and turn angles of up to 20°.

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ASSAD, MARILIA MAURELL. "CHARACTERIZATION OF COMPONENTS DYNAMIC BEHAVIOR IN A PNEUMATIC ACTUATION SYSTEM FOR CONTROL APPLICATIONS ON REDUCED SCALE MECHANICAL SYSTEMS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2013. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=37189@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Sistemas pneumáticos são equipamentos leves, baratos, limpos e de baixo risco, sendo apropriados para aplicações que necessitem de força e rapidez de resposta. Por outro lado, esse tipo de sistema apresenta restrições devido à principal característica do ar: sua compressibilidade confere efeitos não lineares ao sistema, desde um escoamento turbulento pelas válvulas de controle até sua atuação dentro do cilindro – a qual inclui alta sensibilidade ao atrito e volumes inativos durante o curso do pistão. Essas características particulares dificultam seu controle e posicionamento preciso e limitam sua aplicação, principalmente considerando seu emprego em um mecanismo tipo Plataforma de Stewart em escala reduzida. No presente trabalho apresenta-se a modelagem, simulação computacional e análise experimental do comportamento dinâmico de um sistema de atuação pneumático que inclui uma válvula de controle de vazão não convencional, composta de quatro válvulas proporcionais, e um atuador com haste simples de dupla ação. O objetivo deste trabalho é, baseado nos resultados experimentais, determinar as características desses componentes para desenvolver estratégias de controle em tempo real capazes de minimizar os efeitos das não linearidades típicas, visando sua utilização no mecanismo anteriormente mencionado.
Pneumatic equipment is lightweight, cheap, clean and low-risk, being suitable for applications that require strength and high responsiveness. Nevertheless, this type of system has some limitations due to the air main feature: its compressibility results in nonlinear effects in the system, from the turbulent flow control valves to its performance inside the cylinder - which includes high sensitivity to friction and dead volumes during the stroke piston. These particular characteristics make its control and precise positioning difficult, limiting its application, especially when considered its use in a mechanism such as a Stewart Platform in a reduced scale. The present paper presents the modeling, computational simulation and experimental analysis of the dynamic behavior of a pneumatic actuation system that includes an unconventional flow control valve, consisting of four proportional valves, and a double acting single rod actuator. The final goal of this work is to, based on experimental results, determine the characteristics of these components in order to develop real-time control strategies which can minimize the effects of those typical nonlinearities for their use in the mechanism mentioned above.

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Jaafar, Haydar. "Condition assessment of polyethylene pipeline systems." Thesis, Brunel University, 1997. http://bura.brunel.ac.uk/handle/2438/6589.

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This study is an industrial project commissioned by British Gas plc. (UK) to investigate the state of in-service naturally aged polyethylene (PE) buried pipes and to define procedures or techniques available to facilitate the condition assessment programme of PE pipelines systems. The primary goal of this study was to establish a better understanding of the ageing process in commercial piping materials and to understand its effect on long term integrity of PE pipeline systems. Eltex, Rigidex and Aldyl A are trade names of the PE gas grade resins used in this study and they represent the range of pipe materials used in the transport of potable water and gas in the UK. Sections of pipes used in this project were supplied by British Gas plc. in the form of unaged pipes and pipes which were aged in-service. Laboratory based accelerated ageing of the pipe resin samples was also carried out. The ageing regimes considered were water ageing at 23°C, air-oven ageing at 80°C, water ageing at 80 C, vacuum ageing at 80°C and in-service aged samples. Compression moulded plaques were produced as reference material. By utilising specific instrumentation and designs, several reliable procedures were developed to produce specimens directly from pipes. The feasibility of using micro-samples instead of large samples was demonstrated. A methodology was developed to retrieve disk samples using electrofusion "tapping-tee" saddles. Appropriate test specimens were designed for chemical and physical evaluations. This sampling method negates the need for excavating large sections of pipe material for the purpose of condition assessment. Reliable micro and macro-sampling test methods were developed and established as techniques for the condition assessment programme. Characterisation techniques included: (i) differential scanning calorimetry (DSC) to measure (from the same specimen) both the degree of crystallinity and the oxidation induction time (OIT), (ii) HPLC analysis was used to quantify additives concentrations, (iii) Fourier transform infrared spectroscopy was used to monitor the carbonyl index and to identify a pipe resin type from site, (iv) micro- and macro-tensile and fatigue tests to assess the changes in the mechanical properties as function of ageing. The fatigue test procedure was developed to produce brittle fracture at laboratory scale within a shorter period of time as compared to existing procedures such as the hydrostatic test. A reference data-base was created using the above identified tools and the criteria and methodology for carrying out site condition assessment inspection was compiled. The fundamental mechanisms of chemical and physical ageing were studied along with the possibility of their effect on the mechanical properties of PE pipes.

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31

Lyon, Scott M. "The pseudo-rigid-body model for dynamic predictions of macro and micro compliant mechanisms /." Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd219.pdf.

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32

Liu, Y. "Fault detection and isolation for wind turbine dynamic systems." Thesis, Liverpool John Moores University, 2018. http://researchonline.ljmu.ac.uk/8524/.

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This work presents two fault detection and isolation (FDI) approaches for wind turbine systems (WTS). Firstly, a non-linear mathematical model for wind turbine (WT) dynamics is developed. Based on the developed WTS mathematical model, a robust fault detection observer is designed to estimate system faults, so as to generate residuals. The observer is designed to be robust to system disturbance and sensitive to system faults. A WT blade pitch system fault, a drive-train system gearbox fault and three sensor faults are simulated to the nominal system model, and the designed observer is then to detect these faults when the system is subjected to disturbance. The simulation results showed that the simulated faults are successfully detected. In addition, a neural network (NN) method is proposed for WTS fault detection and isolation. Two radial basis function (RBF) networks are employed in this method. The first NN is used to generate the residual from system input/output data. A second NN is used as a classifier to isolate the faults. The classifier is trained to achieve the following target: the output are all “0”s for no fault case; while the output is “1” if the corresponding fault occurs. The performance of the developed neural network FDI method was evaluated using the simulated three sensor faults. The simulation results demonstrated these faults are successfully detected and isolated by the NN classifier.

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Larsson, Tobias. "Effective development of dynamic systems - a structured approach." Licentiate thesis, Luleå University of Technology, 1999. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-11316.

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This licentiate thesis deals with effective simulation of multibody dynamic systems in the product development process. Previous work to make simulation more effective has concentrated on developing faster calculation methods. Instead, this approach is to make the process of multibody dynamics simulation more effective by structuring of products, simulation models and their usage. Efforts have been made to clarify how computer tools are used in product development in industry today. Insight into the two domains of product development and multibody dynamics is given. These domains have traditionally been separated but the introduction of concurrent engineering and faster computers puts new demands on the integration of computer support and analysis in the development process. A proposal for performing the multibody dynamics methodology in a modular way in the product development process is given based on the performed work.

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Sherbaf, Behtash Mohammad. "A Decomposition-based Multidisciplinary Dynamic System Design Optimization Algorithm for Large-Scale Dynamic System Co-Design." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535468984437623.

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Azad, Saeed. "Combined Design and Control Optimization of Stochastic Dynamic Systems." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1602153122063302.

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Houshmand, Arian. "Multidisciplinary Dynamic System Design Optimization of Hybrid Electric Vehicle Powertrains." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479822276400281.

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37

Li, Zhaoyi, and n/a. "Analysis and Design of Virtual Reality Visualization for a Micro Electro Mechanical Systems (MEMS) CAD Tool." Griffith University. School of Information and Communication Technology, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20060731.121340.

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Since the proliferation of CAD tools, visualizations have gained importance.. They provide invaluable visual feedback at the time of design, regardless whether it is fbi civil engineering or electronic circuit design-layout. Typically dynamic visualizations are produced in a two phase process: the calculation of positions and rendering of the image and its presentation as an animated video clip. This is a slow process that is unsuitable fbr interactive CAD visualizations, because the former two require finite element analysis Faster hardware eases the problem, but does not overcome it, because the algorithms are still too slow. Our MEMS CAD project works towards methods and techniques that are suitable for interactive design, with faster methods. The purpose of this PhD thesis is to contribute to the design of an interactive virtual prototyping of Micro Electro Mechanical Systems (MEMS) This research comprises the analysis of the visualization techniques that are appropriate for these tasks and identifying the difficulties that need to be overcome to be able to offer a MEMS design engineer a meaningful and interactive CAD design environment Such a VR-CAD system is being built in our research group with many participants in the team. Two particular problems are being addressed by presenting algorithms for truthful VR visualization methods: one is for displaying objects that are different in size on the computer screen. The other is modelling unsynchronized motion dynamics, that is different objects moving simultaneously at very high and vety low speed, by proposing stroboscopic simulation to present their dynamics on the screen They require specific size scaling and time scaling and filtering. It is these issues and challenges which make the design of a MEMS CAD tool different from other CAD tools. In the thesis I present algorithms for displaying animated virtual reality for MEMS virtual prototyping in a physically truthful way by using the simulated stroboscopic illumination to filter animated images to make it possible to show unsynchronized motion.. A scaling method was used to show or hide objects which cannot be shown simultaneously on the computer screen because of their large difference in size. The visualization of objects being designed and their animations is done with much consideration of visual perception and computer capability, which is rising attention, but not too often mentioned in the visualization domain.

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Li, Zhaoyi. "Analysis and Design of Virtual Reality Visualization for a Micro Electro Mechanical Systems (MEMS) CAD Tool." Thesis, Griffith University, 2005. http://hdl.handle.net/10072/366361.

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Since the proliferation of CAD tools, visualizations have gained importance.. They provide invaluable visual feedback at the time of design, regardless whether it is fbi civil engineering or electronic circuit design-layout. Typically dynamic visualizations are produced in a two phase process: the calculation of positions and rendering of the image and its presentation as an animated video clip. This is a slow process that is unsuitable fbr interactive CAD visualizations, because the former two require finite element analysis Faster hardware eases the problem, but does not overcome it, because the algorithms are still too slow. Our MEMS CAD project works towards methods and techniques that are suitable for interactive design, with faster methods. The purpose of this PhD thesis is to contribute to the design of an interactive virtual prototyping of Micro Electro Mechanical Systems (MEMS) This research comprises the analysis of the visualization techniques that are appropriate for these tasks and identifying the difficulties that need to be overcome to be able to offer a MEMS design engineer a meaningful and interactive CAD design environment Such a VR-CAD system is being built in our research group with many participants in the team. Two particular problems are being addressed by presenting algorithms for truthful VR visualization methods: one is for displaying objects that are different in size on the computer screen. The other is modelling unsynchronized motion dynamics, that is different objects moving simultaneously at very high and vety low speed, by proposing stroboscopic simulation to present their dynamics on the screen They require specific size scaling and time scaling and filtering. It is these issues and challenges which make the design of a MEMS CAD tool different from other CAD tools. In the thesis I present algorithms for displaying animated virtual reality for MEMS virtual prototyping in a physically truthful way by using the simulated stroboscopic illumination to filter animated images to make it possible to show unsynchronized motion.. A scaling method was used to show or hide objects which cannot be shown simultaneously on the computer screen because of their large difference in size. The visualization of objects being designed and their animations is done with much consideration of visual perception and computer capability, which is rising attention, but not too often mentioned in the visualization domain.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Information and Communication Technology
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39

Boke, Tevfik Ali. "Dynamic Stability Analysis Of Modular, Self-reconfigurable Robotic Systems." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606016/index.pdf.

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In this study, an efficient algorithm has been developed for the dynamic stability analysis of self-reconfigurable, modular robots. Such an algorithm is essential for the motion planning of self-reconfigurable robotic systems. The building block of the algorithm is the determination of the stability of a rigid body in contact with the ground when there exists Coulomb friction between the two bodies. This problem is linearized by approximating the friction cone with a pyramid and then solved, efficiently, using linear programming. The effects of changing the number of faces of the pyramid and the number of contact points are investigated. A novel definition of stability, called percentage stability, is introduced to counteract the adverse effects of the static indeterminacy problem between two contacting bodies. The algorithm developed for the dynamic stability analysis, is illustrated via various case studies using the recently introduced self-reconfigurable robotic system, called I-Cubes.

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40

Hagigat, Michael Kent. "Influence of non classical friction on the rubbing and impact behavior of rotor dynamic systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1057602344.

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41

Davies, Christopher Michael. "Study on the dynamic response of a printed circuit board focusing on constraint clearances." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1213368683.

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Moody, Seth Sinclair. "Development of Dynamic Thermal Performance Metrics for Eco-roof Systems." PDXScholar, 2013. http://pdxscholar.library.pdx.edu/open_access_etds/666.

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In order to obtain credit for an eco-roof in building energy load calculations the steady state and time-varying thermal properties (thermal mass with evapotranspiration) must be fully understood. The following study presents results of experimentation and modeling in an effort to develop dynamic thermal mass performance metrics for eco-roof systems. The work is focused on understanding the thermal parameters (foliage & soil) of an eco-roof, further validation of the EnergyPlus Green Roof Module and development of a standardized metric for assessing the time-varying thermal benefits of eco-roof systems that can be applied across building types and climate zones. Eco-roof foliage, soil and weather parameters were continuously collected at the Green Roof Integrated PhotoVoltaic (GRIPV) project from 01/20/2011 to 08/28/2011. The parameters were used to develop an EnergyPlus eco-roof validation model. The validated eco-roof model was then used to estimate the Dynamic Benefit for Massive System (DBMS) in 4 climate-locations: Portland Oregon, Chicago Illinois, Atlanta Georgia and Houston Texas. GRIPV30 (GRIPV soil with 30% soil organic matter) was compared to 12 previously tested eco-roof soils. GRIPV30 reduced dry soil conductivity by 50%, increased field capacity by 21% and reduced dry soil mass per unit volume by 60%. GRIPV30 soil had low conductivity at all moisture contents and high heat capacity at moderate and high moisture content. The characteristics of the GRIPV30 soil make it a good choice for moisture retention and reduction of heat flux, improved thermal mass (heat storage) when integrating an eco-roof with a building. Eco-roof model validation was performed with constant seasonal moisture driven soil properties and resulted in acceptable measured - modeled eco-roof temperature validation. LAI has a large impact on how the Green Roof Module calculates the eco-roof energy balance with a higher impact on daytime (measured - modeled) soil temperature differential and most significant during summer. DBMS modeling found the mild climates of Atlanta Georgia and Houston Texas with eco-roof annual DBMS of 1.03, 3% performance improvement above the standard building, based on cooling, heating and fan energy consumption. The Chicago Illinois climate with severe winter and mild spring/summer/fall has an annual DBMS of 1.01. The moderate Portland Oregon climate has a below standard DBMS of 0.97.

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43

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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Sears, Nicholas C. "Investigations into the Quasi-Static and Dynamic Properties of Flexible Hybrid Electronic Material Systems." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1525278328687427.

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45

Avsar, Ahmet Levent. "Dynamic Modeling And Analysis Of Vibration Effects On Performance In Optical Systems." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609778/index.pdf.

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In order to understand the effects of structurally induced line of sight (SILOS) jitter (vibration) and to predict its effects on optical system performance, a simple and practical vibratory model and software are developed by using discrete and finite element modeling techniques. For an existing simple optical system, discrete and FE dynamic models are constructed and they are validated by modal tests for the frequency range of interest. In order to find material properties of adhesive, which is used in optical system, a simple test is constructed and these properties are found by using a single degree of freedom model. The effects of vibration on the system performance are investigated under random vibration load conditions by using the software developed. It is concluded that the analytical model suggested can successfully be used in preliminary design stage of a simple optical system when the optical housing and lens behave rigidly in the frequency range of interest. The optical performance prediction software combines the optical element tolerances and displacements in order to determine the optical performance.

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Proffitt, Donnie E. II. "EXPERIMENTAL INVESTIGATION TO INFORM OPTIMAL CONFIGURATIONS FOR DYNAMIC NEAR-FIELD PASSIVE UHF RFID SYSTEMS." UKnowledge, 2013. http://uknowledge.uky.edu/me_etds/29.

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RFID has been characterized as a “disruptive technology” that has the potential to revolutionize numerous key sectors. A key advantage of passive RFID applications is the ability to wirelessly transmit automatic identification and related information using very little power. This paper presents an experimental investigation to inform the optimal configuration for programming passive ultra-high frequency (UHF) RFID media in dynamic applications. Dynamic programming solutions must be designed around the tag’s functionality, the physical programming configuration and environment. In this investigation, we present a methodology to determine an optimal configuration to maximize the systems programming efficiency for dynamic applications.

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47

Tan, Sean. "Development of a dynamic model of a ventricular assist device for investigation of control systems." Ottawa, 1996.

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48

Wang, Qian. "A study of alternative formulations for optimization of structural and mechanical systems subjected to statics and dynamic loads." Diss., University of Iowa, 2006. http://ir.uiowa.edu/etd/82.

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Oprisoni, Cristian Alexandru [Verfasser]. "Investigation of the high frequency dynamic-mechanical properties of polymer systems using ultrasonic longitudinal waves / Cristian Alexandru Oprisoni." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2011. http://d-nb.info/104185126X/34.

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Brezina, Aron Jon. "Measurement of Static and Dynamic Performance Characteristics of Electric Propulsion Systems." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1340066274.

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Dissertations / Theses on the topic 'Mechanical dynamic systems'

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