The Pacific Northwest is a particularly good candidate for a
power plant fired with wood since the wood products industry is so
important in the area. The combined cycle concept for such a plant
has increased in popularity due to the generally greater efficiency
of the gas turbine part of...
Wave dispersion and fracture are phenomena that involve. mechanisms triggered at the scale of a material's internal structure. Experiments were performed with a candidate material to judge the hypothesis that wave dispersion measurements can be used to nondestructively predict fracture strength. Wood-based particleboard was chosen as the candidate material because...
An analytical model of the radiative contribution to the
total heat transfer between a large-particle (greater
than 1 mm) gas-fluidized bed and an immersed horizontal
tube is discussed. The model is applied to the case of a
bubbling bed and the emulsion phase contribution is obtained from a detailed analysis...
This thesis presents thermodynamic evaluations of various biomass-fueled combined-cycle power plants using a computer model developed for simulating such plants. The combined-cycle systems Investigated are characterized by having a wood-fueled combustor, an indirect-fired gas turbine, and a steam cycle. This work was part of a larger biomass energy project at...
Three approaches for evaluating mode I interlaminar strain energy release rates in graphite/epoxy composites were compared using experimental data from double cantilever beam specimens. Expressions for evaluating strain energy release rates were arrived at based on assumptions regarding specimen geometry and material behavior. The calculations included the direct method of...
The effects of selected atmospheric variables on the power output
of a DOE Mod-2 horizontal-axis wind turbine are studied. Particular
attention is focused on unsteady, nonuniform flow conditions
within the rotor disc as represented by vertical profiles measured at
adjacent meteorological towers. Primary variables are wind speed,
wind direction and...
The Boleyn home located in Portland Oregon (latitude 45°) is evaluated based on monitoring data taken from 1977 to 1982. The Boleyn home is a two-story (plus basement) frame home. It takes benefit of passive solar gains and is equipped with an active solar system. The active solar system consists...
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...
Dumping drilling mud from offshore drilling rigs into the
ocean could have a negative impact on the marine environment. Due
to this possible impact, the Offshore Operators Committee (OOC) has
deemed it necessary to predict the fate of drilling mud discharged
into the ocean. Through the funding of OOC and...
This report presents the off-design analysis of various
wood-fired combined-cycle power plants using a computer
model to simulate plant performance. The combined-cycle
systems investigated are characterized by having a woodfueled
combustor, an indirect-fired gas turbine, and a
Rankine steam cycle. This work was conducted as part of a
larger biomass...
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....
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...
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...
In this work, a method for solving the differential form of the radiative transfer equation was implemented into an existing three-dimensional thermal-hydraulic computer program known as TEMPEST. The method used was the P-l approximation, where the angular distribution of the radiation intensity is represented by a truncated series of spherical...
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...
This study is primarily concerned with the measurement of the local radiative component of total heat transfer around a horizontal tube immersed in a large particle fluidized bed at elevated temperatures.Total heat transfer was also measured in order to assess the relative radiation contribution.The radiation measurement probe employs a silicon...
This report presents the study of wood combustion and
combustion systems for a combined cycle wood-fired power
plant. The power plant consists of a twin air cycle and a
single steam cycle. The fuel for this power plant is wood
and wood waste with particle size in the range of...
This report investigates the use of wood to fuel a
trimburner incorporated in a combined-cycle, biomass-fired
power plant. The term "trimburner" applies to a
ductburner which is designed to boost the temperature of
the air stream entering the gas turbine. The work
presented here is part of a larger biomass...
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...
This report presents the analysis of ceramic heat
exchangers for use in a combined-cycle, wood-fired power
plant. The combined-cycle system investigated is
characterized by having a wood-fueled combustor, an
indirect-fired gas turbine, and a Rankine steam cycle.
The direct use of low-grade fuels, such as wood, in
present gas turbines...
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...
A simplified model of the combined particle convective and
radiative components of heat transfer between large-particle gas-fluidized
beds and immersed surfaces was developed. This analytical
model was based on the single particle formulation of Adams and Welty
[4,9], with the added assumptions of one-dimensional heat conduction
in the particle and...
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...
An experimental study of the properties of plane jets issuing at various angles into a cross-flow of air was conducted to obtain information relating to the momentum diffusion properties of the jet flow in order to provide a background for predicting the feasibility of the preswirl concept of the Volumetric...
The problems of freezing and melting present special
mathematical complexity and, except for the most elementary
one-dimensional cases, require a numerical solution.
However, these problems have a growing importance in
engineering problems because of their application to
metallurgical operations, food preservation, heating and
air conditioning, etc.
In the present work,...
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...
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....
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...
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...
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....
An information processing model of the problem-solving
performance of mechanical designers is presented for four design
tasks: conceptual assembly design, layout component design, detail
component design, and catalog selection. These tasks are organized
into six kinds of segments called episodes, which describe the goal
structure of the designer while performing...
Heat transfer measurements have been made from a long (L/D = 15)
horizontal cylinder in water parallel to a heated vertical wall. The
cylinder and wall boundary conditions were isothermal, and they were
maintained at equal temperatures. The investigation covered Rayleigh
numbers based on cylinder diameter from 400,000 to 10,000,000....
The influence of microwave radiation on the fabrication
of cermet materials has been investigated for alumina-titanium
cermets with compositions ranging from 20 to 80 wt. % titanium.
An industrial microwave oven was characterized and adapted to
process cermet materials. Physical and mechanical property
determinations were made as a function of...
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...
The effects of laser processing of Ni₃Al, TiAl,
Fe₃Al, and Ni₃Si on microstructure and phase
composition were characterized using optical and
scanning electron microscopy and X-ray diffraction
analysis. It was found that laser processing
resulted in melt zones of ordered phases with fine
grains and microstructures. The effects of heat...
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...
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...
Analytical and numerical study of steady-state laminar natural
convection and conduction has been performed for an enclosure between
concentric vertical cylinders. The inner and outer cylinders were
isothermal, and the connecting top and bottom walls were adiabatic. A
concentric baffle was included in the annulus, and the flow field and...
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....
For control of a flexible manipulator, the assumed- mode method is applied to the mathematical model of the model reference adaptive system. In the assumed-mode method, the flexible, continuous manipulator is described by a limited number of degrees of freedom. A modified model reference adaptive system is studied for direct...
An experimental investigation was carried out to
determine the thermodynamics and fluid mechanics of the
pipe flow of magnetic fluids. A water-based magnetic
fluid was synthesized in the laboratory and its relative
viscosity and magnetic properties were determined
as a function of temperature. A "thermomagnetic pump"
was built and tested...
Only very recently has modern technology been applied
to the design of the tennis racket. In fact, the tennis
player of a few hundred years ago would easily recognize
today's racket. Although the literature reveals a surprising
number of studies on racket mechanics, little work has been
reported on the...
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...
In this thesis, a method is presented to construct minimum-time
robot trajectories for predefined Cartesian end-effector path in a
workspace containing obstacles. The method is preferably applied to a
geometric collision-free path of a SCARA robot by using the theories of
Bezier, B-spline, and parabolic blending curves. The motion of...
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...
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...
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...
An experimental biomass combustion facility has been
built and established at Oregon State University. The
furnace, or Biomass Combustion Unit ( BCU ), uses an augertype
fuel feed system, grate-type fuel support with under
and over fire air supply.
Fourteen pellet species from five States - Alaska,
Washington, Oregon, Idaho,...
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...
Centrifugal casting has been a successful
technique for quickly filling molds, but little is
understood about the fluid flow characteristics that occur
during filling. The understanding of these flow
characteristics and the application of this knowledge
should improve the quality of metal parts cast by this
process. The subject of...
A need exists to develop a high speed dynamic tow carriage used to
motivate hydrodynamic specimens through a fluid environment. It is
desired to simulate high Reynolds number unsteady flow about the
specimen by towing the specimen through the fluid. The fluid
environment is to be provided by the existing...
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...
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...
A computer model was created using compressor and
condenser performance data to simulate vapor-compression
ammonia refrigeration system performance under various
operating conditions and strategies. The model was used to
estimate energy, demand, and cost savings resulting from
reduced condensing pressures.
Two ammonia refrigeration systems were selected for the
investigation into...
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...
This thesis reports on research conducted to determine
the information which should be included in a mechanical
design history. This is part of a larger research effort
aimed at developing a computer tool for storing and
replaying mechanical design history information. Three
question-asking protocols were conducted to determine what
information...
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...
Liquid cooled, laminar microchannel heat sinks were
earlier proposed by Tuckerman for cooling high heat
generating integrated circuits and high power microwave
generation systems using photoconductive switches. A
method of computationally analyzing the heat sinks is
presented which produces the desired temperature and
velocity distributions within the heat sinks. The...
A representation for the process of mechanical design,
along with its computer implementation is presented and
discussed. The representation consists of three
fundamental concepts: design objects, constraints, and
decisions. The design objects are the structures with
which the physical artifacts of the design are described.
A design object consists of...
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...
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...
Cogeneration is the simultaneous generation and use of
both electricity (or mechanical power) and thermal energy
from a single fuel source. It is a technology that has been
used for years by industries, commercial institutions, and
municipalities that need both heat and electrical power. An
analytical approach has been developed...
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...
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...
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...
Self-propagating high-temperature synthesis (SHS) is a new
method of producing advanced ceramic materials and offers an
attractive alternative to conventional methods of materials
processing.
An experimental investigation was carried out to determine
the SHS reaction wave propagation speed in a vertical cylindrical
compact made from a mixture of titanium and...
This thesis presents a method for determining range
of body motion for a walking machine with feet fixed on
the ground. The darkling beetle was selected as the
sample subject in this study.
A closed form inverse kinematic solution is used to
determine if a point in space is within...
Mechanical properties of Nb-Ti composite superconducting wires were tested at
room temperature. The results were analysed using simple composite theory, the rule
of mixtures. The objective is to predict the mechanical properties of Nb-Ti
superconducting composite wires as a function of volume ratio and geometry of the
components, the composite...
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...
Investment casting has been an important form of metal casting
for many years, but little is understood about the fluid flows that
occur during mold filling. A key to quality castings is the
understanding and control of the fluid flows that are present when the
mold is filled with molten...
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...
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...
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...
In current practice, design documentation often fails
to support the activities of design understanding,
communication, and redesign. A Design History Tool has been
developed to improve current design documentation. This
tool is a computerized design history that represents and
plays back important information generated during the
process of designing a...
Combustive Synthesis or Self-Propagating High-Temperature
Synthesis (SHS), is an energy-efficient combustion
method of producing metallic, ceramic and composite
materials from their constituent powders.
This thesis presents the results of an experimental and
numerical evaluation of the propagation velocity for the SHS
solid-solid reaction of titanium and carbon, as well as...
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...
This thesis examines the influence on range-of-motion
of beetle body of changes in leg segment
parameters. From beetle's leg orientation, influence of
the following leg segment parameters are investigated:
coxa length, coxa twist and body-coxa joint.
Kinematic equations are derived for legs of the
beetle. Roots of quartic polynomials obtained...
The application of laser generated ultrasonics was first
demonstrated in the mid-seventies and has shown good potential
when applied to isotropic materials. However, its use with
composite materials is still in the early stages of development.
This study explores the potential for application of laser
generated Rayleigh and Lamb waves...
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...
Ti-6Al-2Sn-4Zr-2Mo-0.1Si specimens were shaped by repeated cycles of heating
(to 954 °C) and hammer or press forging followed by a solution anneal that varied from
968 to 998 °C. The coupons were originally extracted from billets forged below the beta
trans us ( 1009 °C) and slow cooled to ambient...
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....
This thesis investigates a simple dynamic model of the hind leg
of a beetle during initiation of a step. The primary assumption was
that the full load of the body was carried on the hind leg during
this time. That is, the only forces on the body were that of...
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...
An investigation focusing on methods of estimation
of robustness of nominally linear dynamic systems with
unstructured uncertainties was performed.
The algorithm proposed involves the consideration
of an associated system, selection, and subsequent
development, of Liapunov function candidate and integration
of their derivatives along the solution trajectory.
A nominally linear multi-dimensional...
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...
Hydrodynamic effects play important roles in fluidized bed
combustion processes. Since the motion of "bubbles" is an important
influence on fluidized bed heat transfer, a better understanding of their
behavior is necessary for improving the design of fluidized bed boilers.
Using a two-dimensional bed, silica sand particles were fluidized with...
This thesis presents a control system for a walking
machine leg. The leg is representative of one of the six
legs required for a proposed walking machine based on the
geometry of the darkling beetle.
Each of the three joints is controlled by a DC servo
motor mounted to the...
Effective combustion of waste fuels requires an
understanding of the fuels characteristics. Gaseous and
particulate emissions, ash residues and combustion
properties are of interest to many; those that produce and
sell heating units, utilities interested in using the fuels
for power generation, regulatory agencies, municipalities
needing to solve a disposal...
In this thesis the critical parameters involved in the
dislodgement and deformation of microbubbles in laminar
channel flow, are determined and evaluated. Experimentally
the effects of surface tension, viscosity, fluid flow rate,
density, and bubble diameter on bubble dislodgement were
evaluated. A theoretical scale analysis was performed which
provided a...
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...