Describing functions have traditionally been used to obtain the
solutions of systems of ordinary differential equations. In this
work the describing function concept has been extended to include
nonlinear, distributed parameter partial differential equations. A
three-stage solution algorithm is presented which can be applied to
any nonlinear partial differential equation....
A mathematical model of a differential thermal analysis (DTA)
system was formulated so that influence of the various physical parameters
on the DTA peak could be determined. The specific DTA apparatus
simulated had cylindrical sample holes drilled into a nickel
block considered to have a negligible thermal resistance, and the...
Pure aluminum deformed in torsion (shear) at elevated temperatures reaches
a broad "peak" stress and then undergoes about a 17% decrease in flow stress with
deformation to roughly 1-2 equivalent uniaxial strain. Beyond this strain the flow
stress is approximately constant. The sources for this softening are unclear. The
suggested...
In this thesis we consider boundary and initial value problems
associated with the melting of homogeneous cylinders and
spheres. The study includes the temperature distribution in cylinders
and spheres which are perfectly insulated at the surface and
subjected to a heat input respectively along the axis and at the
center....
A phase sensitive measurement technique that permits the simultaneous determination
of two independent thermal properties of thin dielectric films is presented. Applying the technique results in a film's thermal diffusivity and effusivity, from which the thermal conductivity and specific heat can be calculated. The technique involves measuring a specimen's front...
The quality of a digital image pipeline relies greatly on its color reproduction which should at a minimum handle the color constancy, and the final judgment of the excellence of the pipeline is made through subjective observations by humans.
This dissertation addresses a few topics surrounding the color processing of...
Five Ultra light Fabric Reflux Tubes (UFRTs) were tested in a thermal vacuum chamber at the National Aeronautics and Space Administration's Johnson Space Center in September 1994. These test articles were design and fabricated by staff at the Pacific Northwest Laboratory, operated by Battelle Memorial Institute for the United States...
Nearly fifty years after the introduction of skew Brownian motion by Itô and
McKean (1963), the first passage time distribution remains unknown. In this
paper, we first generalize results of Pitman and Yor (2001) and Csáki and Hu
(2004) to derive formulae for the distribution of ranked excursion heights of...
An analytical solution is developed for the temperature
profile of a unit cell consisting of a sphere of one
material centered in a cube of a second material. All
material properties are considered constant and boundary
conditions consist of specified temperatures on the top
and bottom faces of the cube...
With the continued decrease in size and subsequent increase in power of computer processors, thermal management in electronics is becoming more important than ever before. The chip heat densities are reaching new peaks (> 100 W cm-2) that current cooling methods are not able to keep up with. However, some...
A cooling tower system was built and fouling resistances were
studied for cooling water flowing over a heated tubular surface. The
cooling water studied was formulated in an effort to match industrial
cooling water quality. The water used in this study had an average
Ryznar Stability Index of 6.23 and...
This research presents an analysis of thermal stratification in the reactor cold leg of the Advanced Plant Experiment-Combustion Engineering (APEX-CE). This phenomenon may be a precursor leading to a Pressurized Thermal Shock (PTS) event in a nuclear power plant. This work was performed in support of the U.S. Nuclear Regulatory...
This publication is the third in a series of circulars de signed to assist the graduate engineer in reviewing engineering subject matter in order to prepare for registration examinations. As in the first publication of the series, most of the illustrative problems are taken from recent examinations of the Oregon...
Among recently found multi-component Zr-based bulk metallic glasses (BMG), Zr₅₈.₅Cu₁₅.₆Ni₁₂.₈Al₁₀.₃Nb₂.₈ is characterized by its lower critical cooling rate requirement and absence of beryllium as one of the constituent element which makes its handling more convenient. Its large supercooled liquid regions made possible the study of thermodynamics and kinetics of this...
By the investigation of the bulk metallic glass-forming liquids that have very low critical cooling rates, the thermodynamics of metallic glasses can be clarified. For studying thermodynamic properties, such as the specific heat capacity, calorimetry (DSC) is utilized and one of the most used instruments is the differential scanning calorimeter....
The heating rate dependence of the glass transition temperature of the
Ni₆₅Nb₃₅, Ni₆₀Nb₃₅Sn₅, Ni₅₉.₃₅Nb₃₄.₄₅Sn62, Ni₆₀(Nb₄₀Ta₆₀)₃₄Sn₆, and
Ni₅₇Fe₃Nb₃₅Sn₅ metallic glass forming alloys was investigated with a
differential scanning calorimeter (DSC). The inverse heating rate for each
DSC experiment was plotted versus inverse temperature and a Vogel-Fulcher-
Tamman (VFT) type relation was...