Index Catalog // ScholarsArchive@OSU

Wind turbulence input model for horizontal axis wind turbines

Creator:: Lin, Shuh-ren
Abstract:: In order to estimate wind turbine residL2;characteristics in the presence of atmospheric turbulence, the important atmospheric sources for the force excitations felt by the wind turbine system must be identified and characterized. The goal of this research is to develop the wind turbulence input model for horizontal axis wind turbines....
Resource Type:: Dissertation

Wind tunnel simulation and field measurements of flow over a coastal headland

Creator:: Brownlow, Roger West
Abstract:: An experimental study was made of the average and turbulent wind characteristics of the flow over a model of a coastal headland. The scale of the model was 300:1, corresponding to a prototype size of 500 m. The data for validation of the model study was obtained from instruments mounted...
Resource Type:: Dissertation

Volumetric receiver development : a heat transfer and design evaluation of an advanced air heating solar thermal central receiver concept

Creator:: Drost, M. K.
Abstract:: The volumetric receiver is an advanced solar central receiver concept designed to produce high temperature air. This document presents the results of a heat transfer and performance evaluation of the volumetric receiver concept. The volumetric receiver consists of an array of ceramic fins or fibers arranged in concentric rows around...
Resource Type:: Dissertation

Void fraction variations in a fractal-like branching channel network

Creator:: Cullion, Rebecca
Abstract:: Two-phase flow in a fractal-like branching microchannel heat sink may have enhanced heat transfer capabilities over single phase flow in the same branching channel network. In order to exploit this potential, a complete understanding of flow boiling in this geometry is required. The fractal-like geometry is similar to that of...
Resource Type:: Dissertation

Vibrations of suspended cables

Creator:: Gale, John Gregg
Abstract:: The equations of motion of an elastic cable suspended in a viscous medium from two arbitrary points are derived. These are then linearized for the undamped, inextensible case, and it is found that the equations describing the in-plane motion of the cable are then independent of the equation describing the...
Resource Type:: Dissertation

Use of the exergy concept for design improvement of heat exchangers and heat exchanger networks

Creator:: Ranasinghe, Jatila
Abstract:: The second law of thermodynamics, through the exergy concept, allows us to quantify and rationally cost the consumption of exergy (irreversibility) used to drive the heat exchange process and the effluent losses of exergy in a heat exchanger For systems with a network of heat exchangers, the exergy concept recognizes...
Resource Type:: Dissertation

Turbulence induced loads on a teetered rotor

Creator:: Weber, Timothy L.
Abstract:: Development of variable speed horizontal axis wind turbines has resulted in a need for an analysis code with a rotor speed degree-of-freedom. This study develops a five degree-of-freedom time domain computer code that evaluates blade and rotor, mean and cyclic loads with nonlinear aerodynamics together with atmospheric turbulence as a...
Resource Type:: Dissertation

Transient nonlinear deformations of viscoelastic membranes

Creator:: Jenkins, Christopher H. M.
Resource Type:: Dissertation

Three-dimensional, nonlinear viscoelastic analysis of laminated composites : a finite element approach

Creator:: Wang, Min
Abstract:: Polymeric composites exhibit time-dependent behavior, which raises a concern about their long term durability and leads to a viscoelastic study of these materials. Linear viscoelastic analysis has been found to be inadequate because many polymers exhibit nonlinear viscoelastic behavior. Classical laminate theory is commonly used in the study of laminated...
Resource Type:: Dissertation

Thermophysical properties and temperature response of surimi-- measurement and modeling

Creator:: Wang, De-qian
Abstract:: Freezing is one of the important technologies for preservation of foods. In this project, using surimi as a food model, thermophysical properties of frozen foods were evaluated and the freezing process was simulated using a finite element package. To measure temperature-dependent thermal conductivity, a line-source probe system was used. Effects...
Resource Type:: Dissertation

Thermodynamic analysis of geothermal energy systems with forced recovery from aquifers

Creator:: Lee, Se Kyoun
Abstract:: A thermodynamic analysis of forced geoheat recovery from aquifers has been accomplished. The system investigated consists of a single recharging-discharging well pair, in a horizontally extensive aquifer, with either power generation or space heating as surface applications. The space heating systems investigated are (i)direct heating, (ii)heat pumps and (iii)a combination...
Resource Type:: Dissertation

The weldability of ductile iron

Creator:: Rice, William Harold, 1911-
Resource Type:: Dissertation

The design capture system : capturing back-of-the-envelope sketches

Creator:: Hwang, Teng-shang
Abstract:: A system which allows the computer to capture sketches made by a mechanical designer is described. The system not only recognizes basic features as they are sketched, but it also reasons the spatial relationships between features and builds a high level abstract representation (feature model) of the artifact. The temporal...
Resource Type:: Dissertation

The application of a band variable-inertia flywheel to an urban transit bus

Creator:: Moosavi-Rad, Hamid
Abstract:: This dissertation investigates by means of computer simulation the potential of a Band Variable-Inertia Flywheel (BVIF) to store energy for an urban transit bus. Replacing both a fixed-inertia flywheel (FIF) and a continuously variable transmission (CVT), the Band Variable-Inertia Flywheel is capable of accelerating a vehicle from rest to a...
Resource Type:: Dissertation

Tentative equilibrium diagram for the nickel-rich end of the nickel-zirconium system

Creator:: Armstrong, Asa William
Resource Type:: Dissertation

Temperature profiles, thermal diffusion factors, and molecular diffusion coefficients for flow-coupled diffusion in a two-dimensional flow field

Creator:: Laity, Walter William
Resource Type:: Dissertation

Temperature measurement, electrical characteristics, and lorentz mixing of alkali seeded flames

Creator:: Pattee, Heidi Ann
Abstract:: When trace quantities of an alkali element are added to a flame, its optical and electrical properties change significantly. Addition of alkali seed to both premixed and diffusion flames has been used in the development of two new techniques, one for flame temperature measurement and the other for enhanced mixing....
Resource Type:: Dissertation

Stochastic loads on horizontal axis wind turbine blades

Creator:: Freeman, Lisa Nalani
Abstract:: The objective of this work was to develop a method for determining stochastic loads on horizontal axis wind turbine blades. Stochastic loads caused by wind turbulence are a major consideration in designing for long life, cost effective wind turbines. The rotor blades are of particular concern because the blades are...
Resource Type:: Dissertation

Sampling submicrometer particles suspended in near sonic and supersonic free jets of air

Creator:: Martone, Joseph Arthur
Abstract:: This experiment is concerned with sampling submicrometer particles in near sonic and supersonic flows. The study employed a high volume condensation aerosol generator to produce stearic acid particles having a geometric mean diameter of 0.8 μm and a geometric standard deviation of 1.28. The aerosol was diluted with dry air...
Resource Type:: Dissertation

Robustness of uncertain systems : globally optimal Lyapunov function

Creator:: Ahmadkhanlou, Fariborz
Abstract:: The Lyapunov direct method is utilized to determine the robustness bounds for nonlinear, time-variant uncertainies p[subscript i]. Determination of the robustness bounds consists of two principal steps: (i) generation of a Lyapunov function and (ii) determination of the bounds based on the generated Lyapunov function. Presently in robustness investigations, a...
Resource Type:: Dissertation

Robust lateral pulse jet control of an atmospheric rocket

Creator:: Burchett, Bradley Thomas
Abstract:: Uncontrolled direct fire rockets exhibit high impact point dispersion, even at relatively short range, and as such have been employed as area weapons on the battlefield. In order to reduce the dispersion of a direct fire rocket, feedback control is employed to fire short-duration solid rocket pulses mounted near the...
Resource Type:: Dissertation

Robust controller design for robotic manipulators with saturation

Creator:: Liang, Zuyang
Abstract:: The development of modern industries calls for the robotic manipulators with high speed and accurate tracking performance. Many authors have paid attention to robust control of robotic manipulators; however, only few authors have also considered the control problem of manipulators with power limitation. In this dissertation, the robotic manipulator is...
Resource Type:: Dissertation

Response of guyed offshore towers to stochastic loads in the presence of steady current

Creator:: Brynjolfsson, Sigurdur
Abstract:: The validity of the widely used stochastic linearization method for analysing the response of guyed towers to stochastic loads is investigated. The governing equations of a guyed tower have two main sources of nonlinearities, fluid-structure interaction and the restoring force of the cables. In this study, two models are considered....
Resource Type:: Dissertation

Rebound predictions of mechanical collisions

Creator:: Lai, Liang-Ju
Abstract:: Predictions of mechanical collisions between two bodies frequently cannot be completed by the impulse-momentum equation together with a complete description of the motion of the system at the initial contact. Additional account must be taken of the deformations and frictional interaction induced by the impulsive reaction force, where the bodies...
Resource Type:: Dissertation

Rebound predictions for elastic collisions

Creator:: Liu, Pao-pao
Abstract:: In this paper, a numerical method is used to predict the response of an elastic body during a collision in which both normal and tangential impulses are important. Results are compared with those from simplified prediction procedures, which stem from the assumptions that the energy-returning capacity of the normal deformation...
Resource Type:: Dissertation

Purification of zirconium by solid state electrolysis and zone refining

Creator:: Claudson, Thomas Tucker
Resource Type:: Dissertation

Processing of laser interferometric signals for small displacement measurements

Creator:: Peng, Gwo-sheng
Abstract:: Algorithms for analyzing laser interferometry signals were developed and adopted to the computer based processing of small displacement measurements. These methods, matrix operation approach and fixed parameters approach, are based on signal phase calculation and are able to replace complex fringe counting electronic circuits. The matrix operation provides an approach...
Resource Type:: Dissertation

Periodic system analysis with application to wind turbines

Creator:: Bahrami, Mohsen
Abstract:: An algorithm is developed to compute the time averaged, output statistics of a linear system with periodic coefficients forced by stationary white noise. The algorithm makes use of Floquet theory and introduces the averaged system dynamics matrix to obtain more favorable numerical performance. The time series approach to averaged statistics...
Resource Type:: Dissertation

Performance of rotary regenerative heat exchanger--a numerical simulation

Creator:: Bae, Young Lib
Abstract:: This thesis examines the transient and steady-state temperature performance of a rotary regenerative heat exchanger. In contrast to previous studies on this problem, fluid flow in the circumferential direction was considered. Appropriate modeling was included to measure the effect of carry-over on the differential equations describing mass and energy conservation....
Resource Type:: Dissertation

Performance and optimum design analysis/ computation for propeller type wind turbines

Creator:: Walker, Stel Nathan
Abstract:: Development of a performance analysis for propeller type wind turbines is presented. The analysis uses a strip theory approach that includes tip-loss and blade interference. A comparison is presented between analysis and test data. The comparison indicates that the analysis predicts wind turbine performance to an accuracy that is within...
Resource Type:: Dissertation

Parameters affecting mechanical collisions

Creator:: Aum, Ho Sung
Abstract:: Even though the elastic deformations that occur during the impact of colliding bodies may be small in comparison to their actual dimensions, they play an important role in mechanical collisions. During the time the bodies are in contact, elastic, friction, and inertia properties combine to produce a complex variation of...
Resource Type:: Dissertation

Optimal soaring by a small autonomous glider

Creator:: Kyle, Jason A.
Abstract:: Extending the flight time of an autonomous unmanned air vehicle by soaring is considered. A suboptimal controller is developed and successful static soaring is demonstrated with a 6 degree of freedom glider model. Altitude gain rates of between ¼ and ½ m/s are achieved with this simple implementation. A hybrid...
Resource Type:: Dissertation

Optimal design of traction drive continuously variable transmissions

Creator:: Lim, Kyoung Ho
Abstract:: The optimal design technique for minimum power loss in traction drive continuously variable transmissions is developed. The mathematical model is developed to evaluate the traction force and torque in traction drive contact. Kinematic analysis of general traction drive contact is conducted to find the best configuration for minimum power loss....
Resource Type:: Dissertation

On the lyapunov-based approach to robustness bounds

Creator:: Jo, Jang Hyen
Abstract:: The objective of this investigation is the development of improved techniques for the estimation of robustness for dynamic systems with structured uncertainties, a problem which was approached by application of the Lyapunov direct method. This thesis considers the sign properties of the Lyapunov function derivative integrated along finite intervals of...
Resource Type:: Dissertation

Numerical study of natural convection in square partitioned and non-partitioned enclosures

Creator:: Sukkaset, Prasart
Abstract:: Heat transfer characteristics and associated temperature and flow fields for natural convection in two-dimensional, square, partitioned and non-partitioned enclosures have been determined for Grashof numbers ranging from 10³ to 10⁶. The vertical side walls of the enclosure are isothermal with all other surfaces assumed to be adiabatic. An adiabatic partition...
Resource Type:: Dissertation

Numerical modeling of the hydrodynamics of gas fluidized beds

Creator:: Wang, Yusan
Abstract:: This research involves a numerical study of the hydrodynamics of gas fluidized beds. We use the continuum model, treating both gas and particles as interpenetrating continua. The motion of gas and particles is strongly coupled by the interactions between them. For simplicity, we only consider drag forces. We use MacCormack's...
Resource Type:: Dissertation

Numerical analysis of liquid cooling by natural convection for heated protusions simulating vertical plate-mounted electronic components facing an opposing plate

Creator:: Park, Sung-kwan
Resource Type:: Dissertation

Normal modes in nonlinear nonsymmetrical systems with two degrees of freedom, and applications to air springs

Creator:: Moustafa, Mahmoud Abd-Elfattah
Abstract:: The study of nonlinear vibrations of systems having two degrees of freedom has met considerable attention during the past few years. Nonlinear symmetrical systems have received most of it. Normal mode motion of a system is defined as a periodic motion such that the masses of the system assume repeated...
Resource Type:: Dissertation

Nonlinear adaptive control of highly maneuverable high performance aircraft

Creator:: Cho, Sul
Abstract:: This thesis presents an effective control design methodology using a one-step-ahead prediction adaptive control law and an adaptive control law based on a Lyapunov function. These control law were applied to a highly maneuverable high performance aircraft, in particular, a modified F/A-18. An adaptive controller is developed to maneuver an...
Resource Type:: Dissertation

Multiple cooling tower plumes, a field study and analytical model

Creator:: Macduff, Robert Bruce
Resource Type:: Dissertation

Modelling root reinforcement in shallow forest soils

Creator:: Skaugset, Arne E.
Abstract:: A hypothesis used to explain the relationship between timber harvesting and landslides is that tree roots add mechanical support to soil, thus increasing soil strength. Upon harvest, the tree roots decay which reduces soil strength and increases the risk of management -induced landslides. The technical literature does not adequately support...
Resource Type:: Dissertation

Microstructures and properties of Nb/Ti multilayered thin films

Creator:: Faase, Kenneth James
Resource Type:: Dissertation

Micromechanics of heterogeneous materials under compressive loading

Creator:: Laird, George
Abstract:: In mining and mineral processing, compressive loading is often encountered during the comminution of ore bearing minerals and in the wear resistant materials used in the comminution circuit. A common thread joining many of the materials that are primarily used under compressive loading is the presence of a high modulus...
Resource Type:: Dissertation

Mechanics of Nb-Ti superconducting composites

Creator:: Guo, Zhiqiang
Abstract:: Mechanical behavior of Nb-Ti superconducting composites with copper matrices have been studied experimentally and theoretically. Experimental work includes extensive measurements of Cu/Nb-Ti composite system. Techniques for fine fiber testing and composite wire measurement have been developed. Experimental parameters examined in this research include geometry, hardness, Young's modulus, Poisson's ratio, yield...
Resource Type:: Dissertation

Linearized model for wind turbines in yaw

Creator:: Chaiyapinunt, Somsak
Abstract:: The analysis of rigid hub, three-bladed horizontal-axis, axisymmetric wind turbines in yaw is made using a linearized, four-degree-of-freedom model. The linearized equations of motion of rotor and nacelle are developed using quasi-steady blade element theory and Lagrange's equations. The yaw behavior of the system is studied from coefficients of the...
Resource Type:: Dissertation

Lateral pulse jet control of a direct fire atmospheric rocket using an inertial measurement unit sensor system

Creator:: Jitpraphai, Thanat
Abstract:: Impact point dispersion of a direct fire rocket can be drastically reduced with a ring of appropriately sized lateral pulse jets coupled to a trajectory tracking flight control system. The system is shown to work well against uncertainty in the form of initial off-axis angular velocity perturbations as well as...
Resource Type:: Dissertation

Laminar natural convection within long vertical uniformly heated parallel-plate channels and circular tubes

Creator:: Vorayos, Nat
Abstract:: The problem of simple mathematical models of laminar natural convective flow within a long vertical parallel-plate channels and circular tubes kept at uniformly heated walls is revisited to seek a clear physical understanding of heat transfer mechanisms. A series solution method to analyze the fully developed flow and an integral...
Resource Type:: Dissertation

Laminar natural convection in vertical tubes with one end open to a large reservoir

Creator:: Wu, Yissu
Resource Type:: Dissertation

Laminar natural convection in vertical tubes with one end closed

Creator:: Fukuda, Masao
Resource Type:: Dissertation

Kinematics of arthropod legs : modeling and measurement

Creator:: Albright, Stephen L.
Abstract:: This thesis presents a method for determining the kinematic geometry of arthropod legs. A kinematic description makes possible the analysis of arthropod leg motion, as a prelude to investigating how various arthropod species are able to negotiate diverse terrains. Such knowledge will aid in design of legged vehicles. The focus...
Resource Type:: Dissertation

Kinematic analysis of legged system locomotion on smooth horizontal surfaces

Creator:: Baek, Yoon Su
Abstract:: This thesis presents a model of legged locomotion in which position and velocity of body are directly controlled by positions and velocities of feet. One central relationship between foot acceleration, leg stroke and body velocity is developed. Procedures for determining all parameters of a step sequence including periods of constant...
Resource Type:: Dissertation

Investigation of instantaneous hydrodynamics and heat transfer to a horizontal tube immersed in a high-temperature gas-solid fluidized bed of large particles

Creator:: Burr, Marlene Mainland
Resource Type:: Dissertation

Interactions of a fully modulated inclined jet with a crossflow

Creator:: Dano, Bertrand P. E.
Abstract:: Jets in crossflow are used in a wide range of engineering applications and have been studied for more than 60 years. The transversal penetration and structure of a jet placed in a crossflow is known to be strongly three-dimensional. It is believed that, by using a pulsed jet inclined in...
Resource Type:: Dissertation

Integrated forward light scattering as a measure of aerosol mass concentration

Creator:: Tomine, Chris Shinya
Abstract:: A mathematical model was developed that relates the ratio, R, of two light flux measurements to the mass concentration, m, of the atmospheric aerosol particles between a source of parallel light (e.g., the sun) and the measuring system. R is defined as the ratio of the light fluxes passing through...
Resource Type:: Dissertation

Initial performance of rigid, porous sheets of sintered-polyethylene powder for filtering airborne sander dust

Creator:: Anderson, Charles Michael
Resource Type:: Dissertation

Influence of laser processing on the corrosion and microstructure of zirconium based material

Creator:: Reitz, W. (Wayne)
Resource Type:: Dissertation

Influence of environmental factors on human mental and motor performance in console operations

Creator:: Riggs, James Lear
Resource Type:: Dissertation

Human gait analysis by gait pattern measurement and forward dynamic model combined with non linear feedback control

Creator:: Ko, Seung-uk
Abstract:: Normal gait of human is believed to be an adapted motor control result of optimal behavior of individual. Normal gait would be altered by aging or injury without being perceived. Subtle changes in gait which is not easy to detect, can cause many serious problems including joint pains and even...
Resource Type:: Dissertation

Heat treatment characteristics of heavily doped epitaxial silicon materials

Creator:: Wijaranakula, Witawat
Abstract:: Nucleation and growth kinetics of oxygen precipitates and bulk defects in epitaxial silicon wafers were investigated. Low temperature nucleation heat treatments were applied to the well characterized epitaxial silicon wafers before and after the epitaxial deposition processing. Subsequently the wafers were heat treated at a high temperature. In the case...
Resource Type:: Dissertation

Heat transfer in the splash-zone of a high temperature fluidized bed

Creator:: Pidwerbecki, David
Resource Type:: Dissertation

Heat transfer in magnetic fluids at low Reynolds number

Creator:: Choi, Sang Hyouk
Abstract:: This study was concerned with the flow of a magnetic self-propelled ferrohydrodynamic fluid in a horizontal circular tube subjected to axially varying temperature and magnetic field. The first phase of the study involved the analytical solution to the governing equations for the velocity and temperature profiles within the fully developed...
Resource Type:: Dissertation

Fracture energies of Zircaloy and some zirconium alloys

Creator:: Rawers, James C.
Abstract:: The fracture mechanics of Charpy V-notch specimens of Zircaloy-4 and phosphorus contaminated Zircaloy-4 were investigated. Three-point bend and impact tests with Charpy V-notch samples provided an efficient and economical method of fracture evaluation. Fracture failure was monitored by the force-displacement curve. Failure was initially analyzed using fracture toughness values as...
Resource Type:: Dissertation

Fatigue life, fatigue crack propagation and fracture toughness study of 7075 aluminum alloy subjected to thermomechanical processing

Creator:: Lee, Moon H. (Moon Hee), 1949-
Abstract:: Due to its high strength/weight ratio, 7075 aluminum alloy has been widely used as an aerospace material. However, it has relatively low fatigue strength and low fracture toughness in the T6 condition. Thermomechanical processing, including pre-cyclic loading and stretching at high and ambient temperatures, has been investigated with the aim...
Resource Type:: Dissertation

Experimental studies of heat transfer with an array of horizontal tubes immersed in a high-temerature fluidized bed

Creator:: Goshayeshi, Ali
Abstract:: An experimental study is described in which time-average local heat transfer coefficients were obtained for arrays of horizontal tubes immersed in a hot fluidized bed. Spatial-averaged heat transfer coefficients, computed from local values, are also reported. Refractory particles with surface mean diameters of 2.14 mm and 3.23 mm were fluidized...
Resource Type:: Dissertation

Experimental studies of a partially defluidized bed with immersed heat exchange tubes

Creator:: Sitthiphong, Norkun
Abstract:: The object of this research study is to investigate and provide some fundamental information about bed slumping in a partially defluidized bed combustor. Due to the difficulty in making measurements and observations at high temperature, a dynamically similar cold phase fluidized bed was used to model the high temperature case....
Resource Type:: Dissertation

Experimental investigation of wood combustion and combustion profiles in a cylindrical combustion chamber

Creator:: Dadkhah-Nikoo, Abbas
Abstract:: This study presents the results of an experimental investigation of wood combustion. Variables chosen for investigation were fuel feed rate, fuel moisture content, fuel particle size, excess air, fraction and temperature of under-fire air. Data recorded during the experiments included the composition and temperature of the combustion products in the...
Resource Type:: Dissertation

Experimental investigation of natural convection from an array of uniformly heated horizontal cylinders to mercury

Creator:: Wang, Deing
Abstract:: An experimental investigation was conducted to better understand the heat transfer process with natural convection from an array of uniformly heated horizontal cylinders to mercury. Five assembly geometries were studied, these being the single horizontal cylinder, two cylinders with spacing ratios S/D = 2,3 and 4, (S represents the center-to-center...
Resource Type:: Dissertation

Experimental and analytical characterization of bidirectional reflectance data for engineering materials

Creator:: Zaworski, Joseph Robert
Abstract:: Bidirectional reflectance is a fundamental property used for the analysis of radiative heat transfer. It is a form of reflectivity in which the spectral and directional dependencies of both the beam incident on a surface and the beam reflected from the surface are specified. A new system has been designed...
Resource Type:: Dissertation

Evaporator analysis for application to water-source and ice-maker heat pumps

Creator:: Aceves, Salvador M.
Abstract:: Water-source and ice-maker heat pumps share many characteristics. However, each presents different technical difficulties that have prevented them from being used more widely. In a water-source heat pump a very important consideration is to reduce water consumption, while in an ice-maker heat pump a major concern is to reduce the...
Resource Type:: Dissertation

Evaluation of horizontal axis wind turbine blade loads using unsteady aerodynamics

Creator:: Hartin, John R.
Abstract:: Most existing analyses of the blade loads on horizontal axis wind turbines are conducted using linear steady-state aerodynamics, but evaluation of loads resulting from wind turbulence or gusts may not be adequate using these techniques. This study develops single-parameter approximations for both the shed wake and trailing wake components of...
Resource Type:: Dissertation

Estimation of physical parameters in mechanical systems for predictive monitoring and diagnosis

Creator:: Nickel, Thomas
Abstract:: Monitoring, diagnosis and prediction of failures play key roles in automatic supervision of machine tools. They have received much attention because of the potential for reduced maintenance expenses, down time, and an increase in the equipment utilization level. At present, signal analysis techniques are predominantly used. But methods involving system...
Resource Type:: Dissertation

Elastodynamic analysis of a propagating finite crack in a micropolar elastic solid

Creator:: Han, Seog-young
Abstract:: A dynamic propagation of a finite crack of opening mode in a micropolar elastic solid was investigated. By using an integral transform method, a pair of twodimensional singular integral equations governing stress and couple stress was formulated in terms of the displacement transverse to the crack, macro- and microrotations, and...
Resource Type:: Dissertation

Effect of PZT driving waveform and frequency on meniscus shape and dropon-demand droplet formation parameters

Creator:: Yang, Guozhong
Abstract:: For piezoelectric stack (PZT) driven droplet generator, the driving waveform and driving frequency effect on liquid filament shape and droplet characteristics have been experimentally studied. The experimental study was based on a PZT driven droplet generator with known geometric design parameters and working fluid properties. A lumped-element-model (LEM) constructed to...
Resource Type:: Dissertation

Effect of hydrous ethanol on crankcase oil dilution

Creator:: Khalifa, Gamaleldin A.
Abstract:: Adequate lubrication is of the utmost importance in internal combustion engines. Low temperature operation with low-proof alcohol may create some operational problems if alcohol and or water accumulates in the crankcase oil. Condensates of unburned alcohol and water may be blown into the crankcase oil with blow by gases. The...
Resource Type:: Dissertation

Dynamics and control of a rigid/flexible manipulator

Creator:: Yeh, Chun-tien
Abstract:: Control of high-speed, light-weight robotic manipulators is a challenge because of their special dynamic characteristics. In this work, a two-stage control algorithm for the position control of flexible manipulators is proposed. First, the more complex, flexible robot system is replaced by a simplified hypothetical rigid body system (HRRA) with off-line...
Resource Type:: Dissertation

Dynamic modeling, control aspects and model predictive control of a parafoil and payload system

Creator:: Slegers, Nathan J.
Abstract:: Control issues are investigated for a parafoil and payload system with left and right parafoil brakes used as the control mechanism. It is shown through dynamic modeling and simulation that parafoil and payload systems can exhibit two basic modes of lateral control, namely, roll and skid steering. Using a small...
Resource Type:: Dissertation

Dynamic modeling, control and linear theory of a projectile equipped with a rotating internal part

Creator:: Frost, Geoffrey W.
Abstract:: Dynamic modeling of the atmospheric flight mechanics of a projectile equipped with an uncontrolled internal rotating disk is investigated and a modified projectile linear theory is established. It is shown through modeling of this type of projectile that several coefficients of the epicyclic dynamics are altered, leading to changes in...
Resource Type:: Dissertation

Dynamic finite element analysis of micropolar elastic materials

Creator:: Kim, Jong-bum, 1960-
Abstract:: In granular or fibrous materials, in which the dimensions of the internal structure can be of the same order of magnitude as major flaws or holes, classical elasticity theory does not consistently provide accurate models of the large stress gradients that may develop. With the incorporation of additional rotational degrees...
Resource Type:: Dissertation

Ductile fracture of metals under triaxial states of stress

Creator:: Schrems, Karol Krumrey
Abstract:: Silver interlayers between maraging steel base metal were examined to evaluate mechanisms leading to ductile failure in constrained thin metals. The constraint of the maraging steel base metal during uniaxial testing of constrained thin silver results in a large hydrostatic tension component, a small von Mises effective stress, and negligible...
Resource Type:: Dissertation

Ductile facture of metals under high triaxial stress states

Creator:: Tolle, Michael C.
Resource Type:: Dissertation

Drilling process evaluation by predicting drilled hole quality and drill bit wear with on-line acoustic emission signals

Creator:: Wang, Kuang-Jen, 1962-
Abstract:: Improvement of manufacturing productivity is dependent on the successful automation of manufacturing processes, the success of which is based in turn upon the availability of information which describes the state of manufacturing operations. Acoustic Emission (AE) signals related to the cutting process and tool wear have been recently applied to...
Resource Type:: Dissertation

Discrete-time explicit model reference adaptive control for robotic manipulators

Creator:: Yuh, Junku
Abstract:: In this dissertation a direct approach to discrete-time model reference adaptive control (MRAC) based on hyperstability theory is proposed to control industrial robotic manipulators. For industrial robots and manipulators, which usually have highly nonlinear and complex dynamic equations and often have unknown inertia characteristics, it is very difficult to achieve...
Resource Type:: Dissertation

Discrete-time blade pitch control for wind turbine torque regulation with digitally simulated random turbulence excitation

Creator:: Sharif-Razi, Ali-Reza
Abstract:: A time domain simulation model which approximates the three-dimensional velocity fluctuations of wind turbulence has been developed. This model is used in a discrete time control algorithm to regulate the output torque of a wind turbine by changing the pitch angle of the turbine blade. The wind model provides a...
Resource Type:: Dissertation

Direct-sampling optical techniques for the study of transient combustion events

Creator:: Herron, John R.
Abstract:: Techniques have been developed for measuring the temperature, stable species concentrations, and atomic radical concentrations during a transient combustion event. They combine the features of direct sampling with two spectroscopic techniques to produce relatively simple diagnostic techniques to obtain time-resolved measurements. In this study, a transient event was provided by...
Resource Type:: Dissertation

Development of acoustic emissions testing procedures applicable to conventionally reinforced concrete deck girder bridges subjected to diagonal tension cracking

Creator:: Lovejoy, Steven C.
Abstract:: A need exists to develop a non-destructive testing technique that can identify the formation and propagation of diagonal tension cracks in conventionally steel reinforced concrete deck girder (RCDG) highway bridges in the State of Oregon. Such a technique could be included into a structural health monitoring (SHM) system installed on...
Resource Type:: Dissertation

Design of advanced aluminum silicon alloy compositions and processing

Creator:: Li, Xiao, 1963-
Abstract:: Part I discusses the development of an aluminum-magnesium-silicon alloy that may combine strength, extrudability, favorable corrosion resistance with low cost and scrap compatibility. The first part of the study determined the effects of small composition, heat treatment and mechanical processing changes on the ambient temperature tensile properties of the alloy....
Resource Type:: Dissertation

Derivation and automatic generation of Kane's dynamical equations for mechanical manipulators

Creator:: Nie, Tinglin
Abstract:: To design and precisely control a manipulator requires developing an efficient dynamic model of the system. The present work demonstrates how this can be accomplished by employing Kane's dynamical equations. First, a detailed manual derivation of the equations of motion for a particular robot is presented in such way that...
Resource Type:: Dissertation

Combustion mechanisms in wood fired boilers

Creator:: Tuttle, Kenneth Lewis
Abstract:: A program of research has been established at Oregon State University to study wood residue combustion using an experimental spreader-stoker combustor. This research was conducted to increase the understanding of combustion occurring in wood fired boilers. Using Douglas Fir screened to 3/8-3/4 inches, two 4x4 factorial experiments were conducted varying...
Resource Type:: Dissertation

Biaxial fatigue behavior of commercially pure titanium Ti-50A (Grade 2) and low-alloy titanium Ti-Code 12 (Grade 12) heat exchanger materials

Creator:: Tobias, Benjamin C.
Abstract:: Material failures in heat exchangers are often closely tied to events associated with the conditions of service and operating parameters. These events can generally be attributed to adverse load application and higher than optimum operating temperatures that could lead to changes in the microstructure of the materials and fatigue failure...
Resource Type:: Dissertation

Application of linear quadratic control in reduction of aerodynamic forces on aircraft

Creator:: Wei, Shou Yuan
Abstract:: A problem found in high speed transport aircraft is excessive tail loading when flying at cruise speeds through turbulence. Attempts to reduce these areodynamic forces on the tail may result in unstable aircraft motions. Using a linear quadratic regulator in conjunction with a Kalman filter, the feasibility of designing an...
Resource Type:: Dissertation

Analysis of heat transfer, including axial conduction, for laminar tube flow with arbitrary circumferential wall heat flux

Creator:: Faghri, Mohammad
Abstract:: This thesis is concerned with the analysis of heat transfer in a tube with forced flow under conditions of an arbitrary variation of wall heat flux both axially and circumferentially. This total study is separated into two distinct problems which are presented separately. The first is the case of a...
Resource Type:: Dissertation

Analysis of heat pump and steam bleed-off systems linked with thermal-electric power plants to supply low-grade heating and cooling

Creator:: Ileri, Arif
Abstract:: This thesis analyzes two systems that can meet low-grade heating and/or cooling demands by operating in conjunction with thermal-electric power plants. At the application site, one of the systems, HPS, has water-to-air heat pumps that are connected to the supply and return lines of a plant-to-user loop. During heating, the...
Resource Type:: Dissertation

Analysis of energy conversion systems, including material and global warming aspects

Creator:: Zhang, Mingyuan
Abstract:: With the rapid increase of the world energy demand and consumption, the method and techniques to analyze, improve and optimize energy conversion systems have to deal not only with direct fuel exergy (energy) consumption, but also with other resources, which have associated exergy consumptions, and with environmental impacts, such as...
Resource Type:: Dissertation

Analysis and simulation of dual-source heat pumps with three-fluid evaporators

Creator:: Lee, Jai-hyo
Abstract:: When the ambient temperature drops, air-source heat pumps deliver less heating per unit of power input and usually cannot provide for the heating load. Therefore, dual-source heat pumps can offer an attractive alternative. In the context of this work, a dual-source heat pump operates as an air-source unit under normal...
Resource Type:: Dissertation

An investigation of the effects of radial acceleration on a fluidized bed used for filtration of air-borne particulate of submicron size

Creator:: Junge, David C.
Resource Type:: Dissertation

An experimental/analytical investigation of deep submerged multiple buoyant jets

Creator:: Kannberg, Landis Dee
Abstract:: The results of an experimental and analytical study of deep submerged multiple-port thermal discharges are presented. The experimental results include the measured downstream thermal dilution, width, and centerline trajectory of the buoyant thermal plume from multiport jets. Independent parameters for which measurements were obtained include port spacing, discharge Froude Number,...
Resource Type:: Dissertation

An experimental/analytical investigation of buoyant jets in shallow water

Creator:: Hsiao, Entsung
Abstract:: This thesis presents the results of an experimental and analytical study of single-port buoyant turbulent jets discharged into shallow water. The experimental results include the measured downstream dilution, centerline concentration and trajectory. Independent parameters considered were Froude number, submerged depth, discharge angle and velocity ratio. Results indicate that decreasing the...
Resource Type:: Dissertation

An experimental study of radiative and total heat transfer between a high temperature fluidized bed and an array of immersed tubes

Creator:: Lei, David Hsien-Yu
Abstract:: Experimental data are reported for the time-averaged local radiative and total heat transfer coefficients for both an array of horizontal tubes as well as a single horizontal tube immersed in a large-particle fluidized bed at elevated temperatures. Spatial-averaged heat transfer coefficients computed from the local values, using a simple trapezoidal...
Resource Type:: Dissertation

An experimental study of natural convection heat transfer from a horizontal cylinder array vertically aligned to and confined by a single wall and two walls

Creator:: Al-Alusi, Thamir R.
Abstract:: Convection heat transfer was experimentally investigated for two different geometries. One case had three horizontal cylinders in a vertical plane placed between two vertical walls. The second case had three horizontal cylinders in a vertical plane with only one vertical wall. Several different cylinder center-tocenter spacings were investigated. The wall...
Resource Type:: Dissertation

An experimental study of natural convection from protruding arrays on a vertical plate with and without an opposing wall for various fluids

Creator:: Lin, Peng-cheng
Resource Type:: Dissertation

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