Outflowing streams of matter or jets are a common phenomenon in the observeduniverse. The most extreme and powerful jets are relativistic, i.e., they travel at speedscomparable to the of speed light. Gamma Ray-Bursts (GRBs) and Active Galactic Nuclei(AGNs) are two sources of these relativistic jets. In this work I will...
The acceleration in a second-order system is directly controllable
by the input. The Acceleration-Oriented Learning Controller
generates the input to control a second-order system and adjust this
input based on observations of the system's response in order to obtain
a particular acceleration pattern.
Large changes with time and some nonlinearities...
Mountain bike suspension forks have been developed to reduce the
accelerations transmitted to the rider. However, the effectiveness of
suspension forks has not been systematically investigated. It was the goal of
this project to quantify the amount of impact acceleration damping afforded
by three stiffness settings of suspension forks compared...
The Generation IV Very High Temperature Reactor (VHTR) design is being actively
studied in various countries for application due to its inherent passive safe design,
higher thermal efficiencies, and proposed capability of providing high temperature
process heat. The pebble bed core is one of two core designs used in gas...
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...
Given its large population, vigorous and water-intensive agricultural industry, and important ecological resources, the western United States presents a valuable case study for examining potential near-term changes in regional hydroclimate. Using a high-resolution, hierarchical, five-member ensemble modeling experiment that includes a global climate model (Community Climate System Model), a regional...
Normal acceleration characteristics of passenger cars provide valuable information for various aspects of transportation engineering, including use in the geometric designs of intersections, freeway ramps, passing lanes, acceleration lanes, turning bays, or in the development of traffic
simulation or fuel consumption models.
However, the data used in previous studies are...
To understand the forces exerted on structures during tsunamis, model cities are subjected to human-generated tsunamis. The study of vertical evacuation, wherein individuals could take refuge in the upper levels of strong buildings, has resulted in a growing need for a low cost wireless acceleration data logger. Such a device...
This work explores the hypothesis that proton irradiation is a feasible alternative to simulate accelerated thermal aging for Ni2Cr long-range ordered phase formation within NiCr and NiCrFe alloys. In this study, various model alloys and commercial alloys 690 and 690+P (0.01 wt.% P) were subject to 2 MeV proton irradiation...
A short history is given of cathode-ray tubes, from the
earliest laboratory tubes available during the early 1900's through
present day high performance tubes. Special attention is paid to
the development of post-deflection acceleration types especially
band-type PDA tubes and an improvement on that type known as the
helix-type PDA...
The influence of boundary layer pumping on an externally-forced
synoptic-scale flow is examined. The results follow earlier theories of
stratified incompressible Boussinesq flow. These theories state that
the spin-down time scale and the penetration depth of the influence of
boundary layer pumping are inversely proportional to the stratification
and directly...
DSA (Diffusion Synthetic Acceleration) has been developed to accelerate the SN transport iteration. We have developed solution techniques for the diffusion equations of FLBLD (Fully Lumped Bilinear Discontinuous), SCB (Simple Corner Balance) and UCB (Upstream Corner Balance) modified 4-step DSA in x-y geometry. Our first multi-level method includes a block...
The formation of shear bands in isotropic micropolar
elastic materials is considered in this thesis. The
investigation concerns localized deformation fields due to
jumps of second-order gradients of displacement across a
standing singular surface. Such a standing surface gives
rise to a shear band. The condition for the existence of...
Minimizing the number of product terms in a PLA implementation is a large step
towards saving area on a VLSI chip using PLA logic. Due to the large amounts of computer
time necessary to achieve this minimization, a number of heuristic approaches have
been developed to provide near-optimal solutions in...
Steady, longitudinally invariant, barotropic, boundary layer flow is numerically studied at low latitudes where advective accelerations may he large and the Coriolis parameter is small. Flow is generated by specifying the pressure gradient field independent of the flow.
It is found that as the flow approaches the equator, advective terms...
Sea tide heights predicted one year
in advance are manipulated to give accelerations
in centimeters per second per kilometer for the
distances San Francisco to Humboldt Bay and
Humboldt Bay to Astoria. Comparison of these
accelerations to various earth-moon-sun lineups
shows the accelerations are controlled by the
29.53 day lunar...
The purpose of this study was to determine kinetic and kinematic
characteristics of Thai Boxing Roundhouse Kicks. In order to measure the kinetic
variables of peak force and impulse, a triaxial accelerometer was inserted into a
kicking bag. The force data were derived from the known mass and measured
acceleration...
Statement of the problem:
The study sought to determine whether certain
measurable differences existed between students who had
withdrawn after acceptance into the accelerated mathematics
classes in the Portland schools and students who
had persisted after acceptance into the program. Examined
were: scores on the Iowa Tests of Basic Skills,...
We investigate several aspects of the numerical solution of the radiative transfer
equation in the context of coal combustion: the parallel efficiency of two commonly used
opacity models, the sensitivity of turbulent radiation interaction (TRI) effects
to the presence of coal particulate, and an improvement of the order of temporal...
Learning disabled students in special education
programs have not been demonstrating equal achievement
gains in reading when compared to their non-handicapped
peers.
The purpose of this study was to determine the effects
of Accelerated Learning methods in teaching reading to ten
learning disabled middle school students in southwest
Washington.
Accelerated...
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)...
Vehicle dynamics evaluation is divided in two domains: ride quality and handling. The evaluation of characteristics related to both of these domains requires the knowledge of the vibrations developed by the vehicle. Vibrations can be described by acceleration, velocity or displacement (linear or angular). The inertial properties of large vehicles...
An experimental study of the dynamics of a generic rigid body during water impact and an equivalent-radius approximate analytical procedure is developed and calibrated in this study. The experimental tests in a wave basin covered a range of drop heights using a 1/6th-scale model of a practical water-landing object prototype...
Driving simulation is widely accepted as a safe, effective, and economical alternative for investigating driver behavior in a variety of contexts. However, in order to apply simulator-based research results to real-world settings, the performance measures acquired through simulated driving experiments must first be validated. This research was aimed at validating...
Surface waves play a vital role in air-sea interactions, and being able to easily measure them in-situ validates and improves predictive models. Here, we diagnose surface wave properties in the Bay of Bengal using modified vertical SOLO II profiling floats, which are regularly used as part of the Argo ocean...
A preproduction prototype of the MagnaGuard Coupling, model 12.5, has been tested to evaluate its performance. The coupling was tested in both deceleration and acceleration modes, to evaluate its capability to disengage jammed or stalled loads and to provide soft-start, respectively. The unit was evaluated at three different airgap settings...
This work develops the loads, boundary conditions, and model construction techniques used to create a high-level vehicle analysis model. The loads are derived from the overall performance parameters of the vehicle, which include 3 axis accelerations and aerodynamic forces from Computational Fluid Dynamics outputs. The boundary condition of the analysis...
In this dissertation, a group of vehicle dynamics simulation tools is developed with two primary goals: to accurately represent vehicle behavior and to provide insight that improves the understanding of vehicle performance. Three tools are developed that focus on tire modeling, vehicle modeling and lap time simulation.
Tire modeling is...
An Inertial Measurement Unit (IMU) is an important part of a freestanding bipedal robot's state estimation system.
IMUs return translational accelerations and rotational velocities, which must be numerically integrated to obtain a robot's orientation.
This thesis documents the implementation of the IMU alignment and integration systems for the ATRIAS robot....
Recent observations from spaceborne microwave sensors have revealed detailed structure of the surface
flow over the equatorial eastern Pacific in the boreal fall season. A marked acceleration of surface wind
across the northern sea surface temperature (SST) front of the cold tongue is a prominent feature of the
regional climate....
The development of a novel high temperature space radiator is
described. A Rotating Bubble Membrane Radiator (RBMR) combines the
best features of heat pipes and droplet radiators while avoiding
their negative attributes. The RBMR offers light weight, self
deployment, ease of startup and its performance is less affected by
acceleration....
The Adams-Larsen-Pomraning coupled transport model has been used to describe neutral particle transport in binary stochastic mixtures. Here, the mixing statistics are considered to be homogeneous Markovian processes. While the model is robust, the convergence behavior and efficiency of this coupled model have not been addressed. Countless iterative methods could...
By assuming the linear superposition principle to be valid, the
hydrodynamic forces on a horizontal cylinder under waves and current
are examined. In this study, towing a cylinder in waves is used to
simulate a cylinder under waves and current. The experimental
technique is proved valid through theoretical considerations and...
Traditional braced frames are an efficient and economic means of resisting seismic demands. However, braced frames are prone to story mechanisms, which can result in concentrations of demands and damage during seismic events. Including steel strongbacks in conjunction with traditional braced frames can mitigate story mechanisms. The SBF results in...
The characterization of the seismic performance of structures relies on numerical simulations. However, estimates of seismic response are subject to various sources of uncertainty, including modeling uncertainty. This research estimated the response of two full-scale structural specimens composed of a moment resisting frame, elastic spines, and force-limiting connections (FLC), which...
In the companion paper (Chen & Yeh, J. Fluid Mech., vol. 749, 2014, pp. 577–596), collisions of counter-propagating solitary waves were studied experimentally by analysing the measured water-surface variations. Here we study the flow fields associated with the collisions. With the resolved velocity data obtained in the laboratory, the flow...
Using rotated principal component analysis, 200mb wind data from
the First GARP Global Experiment are analyzed in the East Asia winter
monsoon region. It is found that there exist slowly eastward-moving
disturbances with a wind-speed maximum embedded in the jet stream
(jet streak). The implied vertical circulation that is transverse...
The spatial and temporal variability of inner-shelf circulation along the central Oregon coast during the
2004 upwelling season is described using a 70-km-long array of moorings along the 15-m isobath. Circulation
at three stations located onshore of a submarine bank differed from that of a station north of the bank,...
Reactor modeling is largely limited by the computational time required to perform accurate full core calculations. There are many different methods and techniques employed in different reactor simulation codes, but properly modeling all of the physics that takes place in the system requires extensive computational effort. The Coarse Mesh Finite...
Theoretical b:::-eaking criteria for progressive surface gravity waves
are examined, and laboratory and field experiments concerned with breaking waves are reviewed with respect to the testing of these breaking criteria.
The measurements of Komar and Simmons are presented here for the first
time. Only three theoretical breaking criteria have been...
Theoretical breaking criteria for progressive surface gravity
waves are examined, and laboratory and field experiments concerned
with breaking waves are reviewed with respect to the testing of these
breaking criteria. The measurements of Komar and Simmons are
presented here for the first time. Only three theoretical breaking
criteria have been...
In most estuarine systems it is assumed that the dominant along-channel momentum balance is between the integrated pressure gradient and bed stress. Scaling the amplitude of the estuarine circulation based on this balance has been shown to have predictive skill. However, a number of authors recently highlighted important nonlinear processes...
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...
For this project, we designed a soot modeling software to produce a full particle density function. This model uses the Direct Simulation Monte Carlo with a full conditioning particle selection method to capture soot nucleation and coagulation in a diffusion flame. We investigate the use of graphic processing units as...
Engineering applications often require fast, accurate solutions of fluid flow around freely moving bodies. The massive parallelism enabled by graphics processing unit (GPU) architecture enables high performance, offering a promising alternative to traditional solver acceleration via multicore central processing units (CPU). However, fully harnessing GPU parallelism requires specialized algorithms and...
A method to design foot trajectory in Cartesian
coordinates for a six-leg walking machine is presented in
this thesis. The walking machine is based on the geometry of
the darkling beetle.
The walking procedure developed by Y.S. Baek is
introduced first to provide step length and leg swing time
for...
