Contract harvest operations have become the preferred approach to reducing the largest cost component of timber production through free market competition amongst logging contractors bidding or negotiating for work. The goal of this research was to investigate economic components of harvesting operations not previously studied for steep slope thinning harvests...
In certain cases in system modeling, parameter search problems
are complicated by the availability of scanty and corrupt physical
system data and a large number of model parameters. An algorithm
using man-machine interaction is presented to attack this type
of parameter search problem with the objective of efficiency in the...
Biomechanical models have been used in designing human work environments to evaluate potential risks to workers before a work environment is constructed. In order for work environments to be modeled correctly, most biomechanical models require as input, an accurate body posture of the worker. This information can be obtained by,...
This dissertation consists of three papers on land use economics and policies. The first two papers focus primarily on local land use policies and urban development. The third paper addresses the question how environmental amenities affect households' residential choices in a metropolitan area. In the first paper, an option value...
Many engineering devices and propulsion systems suffer from undesirable effects of cavitation; such as degradation in the efficiency of pumps and turbines, generation of noise and vibration on ship propeller, increased drag and erosion of propeller blade, etc.
In spite of decades of research on this problem, detailed study of...
A model is presented which predicts the net present
value of a stand level multi-entry harvest plan. The model
accounts for potential volume losses due to harvest-related soil compaction. The goal of this project was to answer five economic questions about the issue of soil compaction in forestry. The five...
The atmospheric fluidized bed combustor (AFBC) is an alternative to
the pulverized coal burner. The size of a utility scale AFBC would be
enormous so that the use of large particles is necessary to reduce its
size. In modeling the combustion of coal and capture of sulfur released
from the...
A mathematical model of Limiting Dilution Analysis for two limiting
parameters is presented and investigated. Limiting Dilution Analysis is a microbiological
cell assay developed for immunological application. In the given
case we deal with the interaction between B lymphocytes, macrophage derived
factor and T-independent antigens. The state of the art...
Time-domain models were developed to predict the response of a tethered buoy
subject to hydrodynamic loadings. A coupled analysis of the interaction of a buoy and
its mooring is included and three-dimensional response is assumed. External loadings
include hydrodynamic forces, tethers tensions, wind loadings and the weight of both
cable...
There are numerous techniques for improving the mixing of fuel and
oxidant species. However, many of these methods cannot be applied to combustion
systems due to material limitations. A means of mixing the reacting species without
physically invading the flow stream is therefore desired.
In this work, induced electromagnetic forces...
A new method for accelerating the Upstream Corner Balance (UCB) discretization of the equation of transfer is introduced. The inconsistent acceleration equations for the UCB discretization are derived by applying the "Modified 4-Step" diffusion synthetic acceleration technique not to the UCB discretization, but instead to the simple corner balance (SCB)...
Motivated by observations of locally enhanced sea level variability near steep
topographic slopes in regions of strong time-mean flows, effects of zonal ridge topography
on zonal oceanic jet flow are investigated. Unstable wave properties and the
dynamics of eddy-mean flow interaction are evaluated as a function of topographic
geometry using...
The present work is a study of three degenerate, linear parabolic
systems of equations, each of which represents a version of the so-called
double porosity model for underground fluid flows in natural fractured
rock. These systems of equations together with initial and boundary
conditions describe single-phase flows in fluids, slightly...
Hydrodynamic models are used as a diagnostic tool to understand the temporal variability of shallow-water processes that are difficult to completely resolve with traditional field measurements. For all simulations, modeled quantities are qualitatively or quantitatively compared with available measurements to gain confidence in conclusions derived from the modeled results. In...
Mass transfer processes were evaluated in an artificial, non-uniform porous medium with a power law distribution of diffusion rate coefficients obtained from physical characterization of solute and porous medium. Breakthrough curves of several pulse experiments conducted at different velocities were compared (1) to analytical expressions for concentrations at mass transfer...
This thesis considers one of the classical problems in the actuarial mathematics literature, the decay of the probability of ruin in the collective risk model. The
claim number process N(t) is assumed to be a renewal process, the resulting model
being referred as the Sparre Andersen risk model. The inter-claim...
Supplementary mathematical analysis and comparison with the results of tests. This report is one of a series issued in cooperation with the Army-Navy-Civil Committee on Aircraft Design Criteria under the supervision of the Aeronautical Board.
We investigate the optimal harvesting strategies for McKendrick type population models. Models of this type endow the population with a continuous age structure. They consist of a partial differential equation with a boundary condition which involves an integral of the solution. We study two problems, the first concerns the yield...
This paper discusses the development of a computer simulation program for the operation of a log landing for the proposed Helistat airship. The first part of the paper describes the time study used to develop production rates for the chasers, buckers, front-end loaders, and skidders to be used on the...
The principles of mobility are applied to the forest setting to
simulate the movement of logs with a rubber tired-skidder. A computer
program was written to perform the analysis . Vehicle-terrain and logterrain
interactions are the resistances which must be overcome by
the available vehicle power. The rate at which...
The aim of this research is to understand and quantify the modeling differences between CSiBridge and OpenSees, and to determine sensitive model parameters. When designing bridges for the high seismic region of California, the California Department of Transportation (Caltrans) performs nonlinear time history analysis of their bridge models. For three-dimensional...
We present a new mathematical model for the development of biofilm that extends the nonlinear density-dependent continuum model introduced by Eberl et al. in 2001. It is a coupled nonlinear density-dependent diffusion-reaction model for biomass spreading, describing the interaction of nutrient availability and biomass production. The model by Eberl has...
The mathematical technique of overrelaxation is used here to speed the convergence of a numerical method for solving viscous, incompressible fluid flow problems. The method, called MAC, involves approximating the complete two-dimensional incompressible Navier-Stokes equations with analogous finite-difference equations. The MAC method was developed by the Los Alamos Scientific Laboratory...
The effect of entering streamflow on currents of a density
stratified reservoir has been studied in a laboratory model to
provide insight into the prediction, control, and maintenance of
quality water discharge from a thermally stratified reservoir.
Twenty experiments were performed using various concentrations
of a sodium chloride solution to...
The temperature field inside a "truncated" wedge is investigated.
For this purpose the two dimensional Green's function of the
heat equation for this domain is established. Further applications of
these results center around a problem of heat conduction investigated
by Lebedev.
It is popular belief that the volatility of the exchange rate is due
to the balance of payments, which in turn is mainly influenced by the
balance of trade. A closed-loop dynamic economic model is proposed
to describe and analyse the effect of the international trade of a
country on...
An algorithm for computing the parameter sensitivities of an excitation system for a hydroelectric generation system is developed for model analysis in this thesis. The IEEE Type 1 excitation system representation, linked with a simplified alternator and voltage regulator equivalent, provide a closed-loop model for digital simulation. Parametric sensitivities are...
This thesis develops a model for locating field offices for the
Motor Vehicles Division of Oregon. The locations are determined by
minimizing the total cost to the Public. This is reasonable because
the Public finances the operation and the opening of the offices
through tax dollars, and it bears the...
The objective of this thesis is to develop criteria for a data
acquisition system for electrical machinery capable of sampling a
signal every 0.2 msec with a desired accuracy of 0.1%. The system to
be measured includes both AC and DC voltage and current signals from
several points. The main...
Unit cell or pin cell calculations form the basis for
most nuclear core modeling. Because of this, it is of primary
importance to perform these unit cell calculations
accurately.
The subject of this thesis is the analysis of one of
the major approximations made in unit cell modeling, the
infinite...
Pattern recognition techniques and their application to a
consumer behavior study are presented. The Local Majority Method
(LOMAME) utilizes a set of prototypes and corrective factors which
undergo a training cycle before being utilized as pattern classifiers.
Its advantages over the Minimum-Distance Method and the Fix
and Hodges Method are...
A simulation method using a hybrid computer is developed in
this dissertation to enhance the study of wind-driven ocean circulation.
The simulation is based on the mathematical model developed by
Ekman. Pure digital simulation is not economical due to excessive
computer time required for the solution of the partial differential...
An analytical tool to assist municipal planners in evaluating
alternative planning strategies is proposed. Schlager's Land Use
Plan Design Model provides the linear formulation of the problem,
Goal Programming is used to create alternatives, and Brown and Kirby's
Measures of Urban Performance serve to evaluate the alternatives.
Resource Planning and...
Mathematicians have been concerned with population growth
and movement since the days of Leonhard Euler and Thomas Malthus.
Chapter i of this paper sketches the history of the development of the
modern population theory.
In Chapter II, a partial differential equation is derived which
governs the growth and movement of...
The viability of incorporating optimization within budgeting
methodologies is examined.
Resource Planning and Management System and optimization are
proposed as tools to enhance the planning and control functions of the
budgeting process. Three hypotheses are proposed: (1) Integer
Programming, Integer Goal Programming and Dynamic Programming
can be substituted in place...
In this paper, we discuss extensions of two coordinated ordering
methods which reduce inventory costs for multi-item systems.
Goyal's method, which is useful for constant demand, decreases cost
by assigning an order interval for each item, and an optimum number
of purchase orders per period. Goyal's method is modified to...
The economic aspects of quality control have received wide concern since its developmental stages, however, they have not been sufficiently explored. Moreover, as the need for complex products of high precision and reliability increases, most industrial firms have experienced some difficulties in meeting that need at reasonable costs with their...
The exact frequencies and mode shapes of flexural vibration of a
rotating beam are found. The beam has a linear mass and stiffness
distribution.
With certain simplifying assumptions, the kinetic and potential
energies of the rotating beam are found. Hamilton's principle is then
used to determine the equation governing the...
This thesis presents work done to verify the accuracy of a
heuristic method for computing availability percentiles for
cascaded independent systems. Previous work has provided a model
for a single line that will be used as the basis for a simulation
of cascaded and parallel systems of lines. The simulation...
The problem of estimating the parameters of a forced discrete
linear dynamic model is considered. The system model is conceptualized
to include the value of the initial state as a parameter. The forces
driving the system are partitioned into accessible and inaccessible
inputs. Accessible inputs are those that are measured;...
This dissertation introduces a method which
can simulate multi-dimensional Gaussian random
processes by the superposition of sine functions
The fast Fourier transform technique is incorporated into the simulating method to facilitate
saving of computer time.
In view of the fact that the fast Fourier
transform play important roles in digital...
Several dichotomous-response models of carcinogenesis are discussed and their implications for low-dose risk estimation are
examined. In addition, a pharmacokinetic model incorporating non-linear kinetics is studied and the results are investigated with
respect to multiple-pollutant exposures. None of these models appears to suggest the existence of "thresholds".
The analysis of...
This thesis presents a simulation technique for the
post-detection of a point-source trajectory in an
isotropic, stationary random medium. The two-dimensional
source location is estimated from spatially correlated
angle-of-arrival data which are collected simultaneously at
two sensor positions. We assume that the data are collected
at discrete, constant time intervals...
A compartmental model of lymphocyte circulation
through a lymphnode is derived and simulated. The
purpose of the model is to analyze experimental data and
in turn design experimental plans from the analysis in
order to obtain sufficient data for the organ-distributed
immune response. The model will be used to predict...
Two packages of subroutines were developed to perform material
balances on chemical processes using the simultaneous modular
approach and the equation-based approach. The performances of these
packages were compared for five different processes under at least
two conditions: one with no design specifications, and one with two
or more design...
ANSI/ASQC Z1.4 is a widely used attributes
acceptance sampling system. A necessary aspect of a
scheme, from both a theoretical and psychological
viewpoint, is the switching between normal, tightened,
and reduced inspection as a function of quality
history. In the latest revision of the standard the
switching rules were altered...
The focus of this research is to develop a personal computer based simulation model of the mechanized logging process, from felling until the log arrives at the sawmill. The SLAM II simulation language is used for modeling, and the main emphasis is on the overall performance of this system, and...
Dredged spoil plumes are monitored during nine hopper dredge
disposal events in 186 foot water depths offshore near Coos Bay,
Oregon. Position and solids volume concentration characteristics of
the plumes are established.
Computer simulations of the monitored events are executed using
the WES modified version of the Koh-Chang instantaneous disposal...
Mathematical models of the precipitation process are needed to
effectively use historical precipitation data in the design and
planning of engineering projects and for analysis of watershed
runoff behavior. Existing simple models based on the assumptions of
independent, identically-distributed random variables are
insufficient to describe several features of the historical...
A test system was developed and used to
investigate ice/structure interaction with centrifugal
modeling. The test system was designed to perform two
main functions: (1) create a uniform ice sheet, and
(2) drive a model structure through the ice sheet at a
constant speed. Both of these functions were required...
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...
A dynamic model of a refrigerant boiler has been produced by
the use of distributed parameter modeling techniques. A number
of elementary cases were studied and were used as an aid in the
final model formulation. Modeling using distributed parameters
employed the use of mesh equations which were then reorganized...
Mass transfer from a single rising gas bubble in water may be analyzed by numerical methods. In this study the simultaneous differen- tial equations which describe two component mass transfer from a rising gas bubble are solved by numerical integration. This is accomplished using a computer model which employs a...
In order to develop three models for use in quantifying the
environmental conditions of reforestation, extensive measurements
required for energy balance calculations were taken for a
reforestation site in southwest Oregon. The models are used to
decrease the number of measurements required to properly evaluate
the potential for heat or...
Mathematical models for the doubly-fed machine are
presented. The properties of the machine with rotor excitation as supplied by a power converter with voltage
source character are reviewed. The peculiar torque-speed
characteristic of the machine in this operating mode and
its effect on the stability of the machine are presented....
A generalized mathematical model of ecosystems is
developed. The model begins with the general class of
systems known as state-determined systems, in which the
time-derivative of each state variable is a function of some
subset of the set of all system state variables and
.environmental parameters. A formal basis is...
The oxide/electrolyte solution interface has been studied experimentally by two methods, and a mathematical model for the interface has been developed. The change in interfacial potential with solution composition was determined through the capacitance of electrolyte/oxide/semiconductor (EOS) structures and the charge through potentiometric titrations of colloidal oxide suspensions. The differential...
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....
Three areas of liquid state theory are considered.
First, Monte Carlo computer simulation of a two-dimensional hard
disk fluid with an imbedded ellipse was undertaken to determine how a
non-spherical molecule affects intermolecular ordering. The
elliptical molecule (with axial ratios of 2, 5 and 10) altered the
isotropic distribution of...
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 success of civil engineering construction in cold regions often depends on the
assessment of the potential for frost heave. Over the past two decades two models have
been presented to the engineering community to identify the frost heave potential,
namely: (1) the segregation potential (SP), and (2) the discrete...
Neural networks are models which have been developed to simulate the anatomy
of the nervous system. The connection between the elements of these networks,
the so called artificial neurons, is similar to the connection between the biological
neurons. In developing neural networks people are trying to create systems which
have...
Impact is a large and complex field. It embraces both structures as simple as a
nail, and more complex systems, such as a car collision. A central feature of impact
theory is finding the dependence between the velocities before and after impact. The
transformation law of the velocities in an...
Design phase decisions based on diagnosability lead to lower system costs and, in turn, higher quality products by means of reducing maintenance time and increasing system reliability. A case for diagnosability is presented. Functions of diagnosability are expounded upon including life cycle costs, statistical analysis, and design criterion to emphasize...
This thesis presents an examination of the nearshore wave bottom boundary layer
under conditions of significant sediment response. Using both field observations and
simple models, the response of the bottom boundary layer to random waves is shown to
have a complex behavior. First, the linearized wave bottom boundary layer governing...
This dissertation addresses three topics on applied microeconomics. First, we investigate issues of market power and tax incidence in the U.S. brewing industry. Since alcohol consumption can be addictive, we derive a structural econometric model of addiction from a dynamic oligopoly game. This model identifies the degree of market power...
A two-dimensional numerical mesoscale model, which ic1udes
radiative and turbulent transfers, has been constructed to study the
formation, development and dissipation of coastal stratus cloud
under an inversion. In the model, the delta-Eddington and emissivity
approximations are used for the solar and thermal radiative
transfers, respectively. K-theory parameterization is adopted...
The thesis examines the applicability of a two-dimensional flow acceleration model to describe a terrain-induced flow perturbation as measured at Yaquina Head on the central Oregon coast. The geometry of Yaquina Head together with the upstream wind values were used in estimating hilltop winds. These estimates compare well with the...
A global, multi-level, wave-mean flow model based on an
approximate version of the primitive equations is developed to
investigate the development of a baroclinic wave field initially
confined to a single zonal wavenumber. The effects of physical
processes (surface drag and thermal damping) and internal diffusion
on the evolution have...
A modeling study is undertaken to better understand the physics of katabatic flows. This study is divided into three topics; a comparison between a large eddy simulation (LES) and a mesoscale model of katabatic flows, a sensitivity study of katabatic flows to various physical parameters, and an investigation into the...
One dimensional nonlinear difference equations have been used to model population growth. The standard biological models have the interesting characteristic that
they display global stability if they display local stability. Various researchers have sought
a simple explanation for this agreement of local and global stability. Here, we show that
enveloping...
The principal aim of this study was the use and evaluation of dynamic
modeling techniques to identify mathematical models for cereal drying rates and
quality changes that best describe thin-layer malt drying data. Seven thin-layer
malt drying experiments were performed at the Great Western Malting pilot
facilities, Vancouver, WA. Malt...
Reach defined analysis concentrated on the water temperature change that occurred in a stream/river segment over the course of one full diurnal cycle. Digital thermistors, data loggers and computer model development were utilized in reach analysis to link parameters of the stream system to a specific temperature change. The methodology...
Policy analysts designing programs to improve the
efficiency and expand the use of water in the irrigation of
farm lands often enlist benefit-cost analysis as a means of
assessing impacts and feasibility. While on-site comparisons
of costs and benefits are important factors in project
assessment, other dimensions such as risk,...
Shear waves, which are instabilities of the longshore current, are of interest
to nearshore research because they can act as a cross-shore mixing mechanism
for the current. The best method to study them is in a controlled environment,
such as circular wave tank where continuous longshore currents can be
generated....
We present a study of the ocean circulation using state of the art numerical and data assimilation techniques. The second chapter of the thesis presents the development and application of generalized inversion to a simple dynamical model of Lake Kinneret. The intent was to develop the necessary tools to implement...
The main focus was on developing an algorithm and supporting computer programs for use by extension personel to counsel farm managers on problems of enterprise choice. Investigation was initiated from the complete certainty viewpoint of linear programming. Upon introducing uncertainty, ramifications of changing expected income, variance and the correlation coefficient...
Essential to the testing of propositions in economic theory is the estimation of the parameters involved in relationships among economic variables. Probably the most widely used method of estimation is ordinary least squares (OLS). However, severe multicollinearity or near linear
dependence of the explanatory variables can cause the OLS estimates...
A flexible flowshop, comprised of one or more stages having unrelated parallel machines, is investigated in this research. Unrelated parallel machines can perform the same function but have different capacity or capability. Since this problem is motivated by industry research, dynamic job release times and dynamic machine availability times have...