Two basic approaches to reduce computational requirements for solving
distillation problems have been studied: simplifications of the model based on
physical approximations and order reduction techniques based on numerical
approximations.
Several problems have been studied using full and reduced-order
techniques along with the following distillation models: Constant Molar
Overflow, Constant...
The extraction of pentachlorophenol (PCP) from pressure treated wood
wafers with supercritical carbon dioxide has been studied. Experimental data
were obtained for the effects of pressure (17.5 - 25.0 MPa), temperature (313 - 353
K), flow rate (1 - 3 ml/min at supercritical conditions), and sample size (0.8 x 10...
A review of Single-Input Single-Output Internal Model Control
(IMC) is presented, showing its relationships to the Dahlin
algorithm, PID type controllers for simple models with and without
deadtime and Smith predictor control.
The effect of errors in the time constant and the gain of a
first order model with deadtime...
The temperature-time-location relationships during steam conditioning and pressure
treatment of timber poles have been studied and mathematical models that take into
account both the thermal properties of the poles and the parameters of the treatment
process have been developed. Although much work has been previously done in this
area, the...
Two approaches to reduce computational requirements for solving reactive
distillation problems have been studied: simplification of the model using physical
assumptions and numerical approximation using an orthogonal collocation technique.
The results of a full-order model with time dependent stage molar holdups was
compared to published steady-state experimental data and was...
A computer assisted design model, developed for
undergraduate students to teach the basic principles of
humidification design, is developed and presented.
Beginning with the development of the differential
equations, the conversion to numerical code is presented,
followed by a series of applications to mechanical draft
in cooling towers, natural draft...
This thesis examines the transient performance of packed bed heat
regenerators when very large temperature differences are involved. The
effects of gas temperature on the key gas physical properties of velocity,
density and heat capacity were studied via simulation.
Three models were developed and compared. The first model
(HRKDV) considers...
The principal objective of this study was to investigate process simulation and
optimization of an existing offshore natural gas process which needed profitability
improvements. Optimization was done using two alternative approaches: a global
approach (response surface methodology) or a local approach (successive quadratic
programming). The global approach was characterized by...
A column which contains a series of three fluidized
beds for counter-current contacting of solid particles with
a gas stream has been studied. Successful, independent
control of solids holdup on each stage has been achieved by
manipulating the field of a magnetic distributor-downcomer
on each stage. Two methods to manipulate...
This thesis examines the transient response of a packed bed heat
regenerator when heated from an initial uniform bed temperature. Very large
(1700 K) temperature differences were studied as well as the effect of
simultaneous chemical reaction in the gas phase.
First the effects of temperature on physical and transport...
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...
A digital phase locked loop (DPLL) and a statistical time-to-digital converter (STDC) were previously fabricated in a 0.35µm, 3.3V SOI CMOS process. This work summarizes these designs and characterizes the measured performance. Simulations supplement the measurements where applicable.
The DPLL was found to reach a locked state under a limited...
Pediococcus cerevisiae, Lactobacillus casei, Lactobacillus plantarum,
Leuconostoc mesenteroides, Lactococcus diacetylactis Bifidobacterium
bifidum, Leuconostoc oenos, and mixed cultures of Propionibacterium
shermanii and P. cerevisiae were used to ferment cucumber juice brine
(CJB) at 22-26°C for 1.5 months. Sugar utilization ranged from 14.6 to 86.1%.
pH of the fermented CJB ranged from...
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...
Ferrites have been used for various high frequency applications as bulk
materials. These applications, however, are limited to large dimension devices. In
this thesis, thin film ferrites were deposited from a low temperature solution-based
deposition process that is suitable for micro-scale high frequency applications. The
low temperature nature of this...
The design of two 2.4GHz CMOS LC balanced oscillators in the 0.25μm National BiCMOS process for Bluetooth specifications is presented. These oscillators achieve low phase noise with low power consumption. At a frequency offset of 500KHz from the 2.11GHz carrier, the measured phase noise is -101.9dBc/Hz for the NMOS oscillator...
This thesis examines substrate noise coupling for NMOS transistors in heavily doped substrates. The study begins with the analysis of an NMOS transistor switching noise in a digital inverter at the device level. A resistive substrate network for the NMOS transistor is proposed and verified. Coupling between N+- P+ contacts...
The brain has long attracted the interest of researchers. Some tasks, such as pattern
recognition and optimization, have proven to be exceptionally difficult for conventional
computing systems to perform, but are executed by the brain almost effortlessly. Due to
the large number of neurons and interconnections, it has proven impossible...
Retention of engineering students is a problem for many universities, especially during the first year. The problem of introducing students to engineering while increasing retention rates has recently been addressed by many different universities. Implementing novel lab structures, adjusting the lecture to incorporate more effective teaching techniques, and using orientation...
This study examines the effects of pressure, temperature, and treatment time on supercritical fluid impregnation of such composites as plywood, particleboard, flakeboard, and medium-density fiberboard. Carbon dioxide with methanol as a cosolvent was used as the supercritical fluid, with tebuconazole as the biocide. Biocide distribution, as measured by extraction and...
The effect of process variations under supercritical conditions on cyproconazole retention and distribution in ponderosa pine sapwood boards was assessed. While pressure and temperature appeared to affect biocide solubility to some extent, the overall results suggested that biocide movement into wood was influenced more by diffusion than bulk flow. Biocide...
The effects of supercritical fluid (SCF) impregnation on physical properties of composites were investigated at various pressures, temperatures, and treatment times with carbon dioxide as the fluid and tebuconazole as a biocide. In general, within the ranges tested, SCF treatment had no negative effects on modulus of rupture (MOR), modulus...
The development of pressure inside wood during preservative impregnation was studied using Douglas-fir heartwood and ponderosa pine sapwood. Pressure sensors mounted on sample holders provided the most reliable measurements. As expected, pressure equilibrated most rapidly with air as the treatment medium and ponderosa pine as the test species. Pressure changes...
A simple heat exchanger network has been studied as
an example of a dynamically interactive process. The
process is relatively simple, requiring only temperature
measurements and flow rate manipulations. Equations are
presented for the design of a physical process having a
specified steady-state Relative Gain Array and specified
dynamic characteristics....
The major historical studies that have examined American
biology have emphasized the development of experimental biology at
the end of the nineteenth century. In this characterization, the
descriptive branch of biology has often been treated as less than
important and, in several cases, as a hindrance in the application
of...
Covalent organic frameworks (COFs) are an emerging type of microporous crystalline polymers connected by organic units via strong covalent bonds. Due to the well-defined crystalline structure and excellent chemical and thermal stabilities, COF materials are being considered as promising candidates in a variety of applications, such as gas adsorption, catalysis...
The need for less toxic quantum dots (QDs) has led to a significant number of investigations related to copper indium sulfide (CIS) QDs. Lower toxicity and broad band absorbance width makes CIS QDs appealing for light emitting diodes (LEDs), lasers, sensors, bio-imaging, solar cells, and computing. The optical and electronic...
Digital inkjet printing is developing quickly today because inkjet printing processes consume less energy and water and produce less waste discharge than traditional dyeing and other printing technologies. Inkjet printing provides more versatility and flexibility in terms of printing patterns and colors. Natural pigments are gaining more attention today as...
The effect of supercritical fluid treatment on superficial gas permeability of Douglas-fir was investigated by using carbon dioxide either alone or amended with methanol. Permeability increased in a majority of samples, although nearly one-third of the specimens declined in permeability. Improvements in permeability appeared to be unrelated to variations in...
Adverse effects on mechanical properties from using a supercritical fluid (SCF) to increase preservative penetration of refractory woods were evaluated by treating small ponderosa pine sapwood specimens with supercritical carbon dioxide at 64 combinations of temperatures (35 to 80 C), pressure (1,000 to 4,000 psig), and time (0.5 to 2...
These essays are an attempt to rebuild memories that explore the nature of work and family. They explore how work knocks against the joints of the body and against the joints between family members, and, as time passes, how the next generation inherits the family line of work only to...
Steam distillation is the traditional method used for the extraction of peppermint oil. This process is able to remove approximately 20% of the oils from the leaves of the plant. It is a very costly and un-sustainable process due to the release of carbon emissions. Solvent free microwave extraction promises...
Most general purpose protocols are found to suffer from
inefficiency in an Ethernet LAN environment when used for large
volume data transfer. This is especially true with the TCP/IP family
which was designed for a wide area network. This research work
presents a proof of this inefficiency and proposes a...
This work focusses on the modeling and the development of efficient coupled simulation techniques for MEMS based RF oscillators. High-level models for MEMS based varactors have been discussed and their accuracy issues are identified, based on comparisons with numerical simulations. A faster simulation approach based on the time-domain shooting method...
Supercritical fluid (SCF) impregnation is a promising preservative treatment method, however, the development of SCF processes has been slowed by a limited understanding of the process. Developing a better understanding of the effects of various process parameters on treatment results would allow for a more rational development of SCF impregnation....
The benefits of physical activity (PA) are well established (USDDHS, 2008). Concern over the high rate of childhood obesity, however, has highlighted the emphasis of PA. Yet, children and adolescents are not obtaining the recommended amount of PA (CDC, 2011). Physical education (PE) has been recognized as an important source...
A new technique is developed to recover elemental tellurium (Te) from cadmium telluride (CdTe) which is abundantly available in photovoltaic semiconductor waste. The method is based on microchannel fluid flow with the use of a supported liquid membrane (SLM) between the donor (feed) and acceptor (strip) channels. A predictive theoretical...
Renewable energy is a topic of significant interest and importance in the world today. Ocean wave energy, particularly in areas such as the Oregon Coast, has considerable potential as a renewable resource. However, to rightly evaluate the overall cost of energy for wave energy converters, survivability and maintenance issues must...
The low physical activity levels of children today are a cause for serious concern. When examining certain populations of children, such as children with Autism Spectrum Disorder (ASD), there is a possibility of even lower overall physical activity levels. However, when exploring the current literature examining the physical activity levels...
Cellulose nanocrystals (CNCs) have received considerable attention over the last ten years because CNCs can be produced from renewable materials such as straw, wood, cotton, and sea animals (tunicates). CNCs are slender rods with high aspect ratios (10-100) and the final dimensions of the CNCs depend on the starting material....
Polyethylene terephthalate (PET) polymer has been the material of choice for packaging industry as a result of its excellent mechanical and physical properties. These properties are highly dependent on the microstructure, chemistry, and processing conditions of this material. PET is often oriented in the machine direction (MD), the transverse direction...
Efficient usage of resin is of critical importance to industry in the manufacture of wood composite panels, because resin represents a significant proportion of product costs. However, resin efficiency is poorly defined in literature, making it difficult to compare manufacturing processes in quantifiable terms. Additionally, resin content in the product...
The hydrogen economy is a possible component of an energy future based on use of alternative and renewable energy sources, deemed desirable from the general consensus of the worldwide community that we do not want to further exacerbate the climate problems that we have introduced over the last two centuries...
Resistance to moisture uptake is an important attribute of some wood preservatives and can help reduce moisture cycling that leads to the development of deep checks. While the potential for preservative treatments to help improve wood/moisture interactions is acknowledged, there are no tests that specifically evaluate this performance parameter. Checking...
Meeting the energy demands of the future is one of the most important challenges facing the engineering community today. An example of this problem is transportation fuels. Most of the current transportation fuels are composed of petroleum hydrocarbons. Finding a viable alternative is important given the potential scarcity of these...