On a global scale, illicit economies have dramatic impacts on the physical environment. Cocaine trafficking has been recognized as a major driver of deforestation inside Central American protected areas. A key problem in studying and managing the environmental impacts of illicit economic activity is the difficulty in obtaining reliable data....
The sensors in real time data processing IoT devices require high resolution and sub-MHz data converters, usually implemented as Incremental ADCs due to the advantages of oversampling technique and low latency. In discrete time incremental (IDT) ADCs, the sampling switch non-linearity, charge injection degrade the resolution, and power hungry OPAMPs...
A modeling technique for simulating the noise
performance of chopper-stabilized switched-capacitor
filters using SPICE2 is presented. A method for
selection of switched-capacitor network (SCN) stages
to be chopped and an op amp topology for low noise
applications are also outlined. Validity of the
modeling is verified by the close agreement...
The chopper-stabilized operational amplifier has good low
frequency noise properties. Unfortunately a simple technique for
simulation of the chopper-stabilized operational amplifier has
not been available.
This thesis describes the implementation of a differential
amplifier using chopper stabilization and its circuit modeling
for the SPICE simulation. This circuit has been designed...
A short-circuit-protected line-driver circuit is
particularly adapted for use in a CMOS differential line-driver
system, where one line-driver circuit provides a
true output signal, and another line-driver circuit
provides a complementary false output signal. A short-circuit
is sensed by measuring current through a secondary
pull-up transistor, and disabling a primary...
The performance of transit networks must be measured on a regular basis to understand how well these complex systems fulfill their intended purpose and to identify potential opportunities for improvement. Measuring transit network performance is only achievable by defining a specific set of transit network performance indicators (TNPIs). Different schemes...
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J. DavidPorter
The performance of transit networks must be measured on a regular basis to
The determination of the optimal location of transceivers is a critical design factor when deploying a wireless local area network (WLAN). The performance of the WLAN will improve in a variety of aspects when the transceivers' locations are adequately determined, including the overall cell coverage to the battery life of...
Pulse Width Modulation (PWM) has been used extensively for motor control, DC-AC
converters, DC-DC converters and in audio applications. The conventional method of
generating a pulse width modulated signal involves generating an accurate sawtooth or triangle
wave using analog circuits. In CMOS, being analog circuit intensive puts extra constraints
on...
A fast-settling CMOS operational amplifier using the
folded-cascode topology has been designed. The design is
based on a theory developed by Yang et al for the optimum
settling time of two-pole systems for switched-capacitor
applications. The theory states that the two poles are
separated by a given factor in order...
In any biomedical signal acquisition system, a front-end amplifier is needed to amplify low amplitude bio-signals while filtering out any unwanted low-frequency artifacts. The design of low frequency poles within the sub-Hz range implies very large time-constants which goes against system integrability. In recent years, the pseudo resistor has been...
A high-swing, high-linearity Class-AB CMOS
operational amplifier suitable for high speed
application is presented. It does not exhibit large-signal
slewing effects as do others; its output current
is limited by MOSFET aspect ratios and the total power
supply voltage. A rail-to-rail common-mode input range
is achieved by a topology which...
A circuit topology for high-swing, high-linearity
CMOS operational amplifiers has been developed. The
technique uses parallel-connected p- and n-channel
input pairs to realize an input common-mode voltage
range nearly equal to the total power supply voltage.
High linearity is achieved by summing the DC bias and
AC small-signal currents so...
Organizations are constantly looking for innovative strategies to face more stringent competitive environments and the ever increasing market globalization. An alternative these organizations can pursue to respond to these challenges is to optimize their supply chain network (SCN). Important considerations when optimizing a SCN involve determining locations for plants and...
The semiconductor gallium arsenide (GaAs) has many potential
advantages over the more widely used semiconductor silicon (Si).
These include higher low field mobility, semi-insulating substrates,
a direct band-gap, and greater radiation hardness. All these
advantages offer distinct opportunities for implementation of new
circuit functions or extension of the operating conditions...
The integration of photodetectors with IC circuits provides a significant
improvement over conventional designs. Featuring noise reduction, extended frequency
responses, lower power consumption, and data operations, these integrated devices open
challenging opportunities for many applications. One type of photodetector has the
potential for important applications in the life science and...
Modern supply chains have grown to be far more complex than their predecessors, as global trade and accessibility have opened avenues of trade that were previously impossible. As such, the inherent risk of internal and/or external disruptions impacting the performance of a supply chain has also grown due to the...
The bandgap voltage reference technique, as implemented in Silicon technology, has evolved to a state of advanced development and become the method of choice for temperature independent voltage biasing in integrated circuits. The heterojunction bipolar transistor (HBT), fabricated from epitaxial A1GaAs /GaAs, is developing to a point where basic circuit...
The rapid advancement of manufacturing has led to the creation of a myriad of technologies that facilitate the analysis and simulation of manufacturing processes. These technologies have become a pivotal component in maintaining and improving processes in today’s complex manufacturing environments. Discrete Event Simulation (DES) is one such technology that...
Analog computation in the form of neural networks is currently
receiving much attention. Existing algorithms cannot be easily
implemented in hardware because of the large number of neurons needed
and the number of connections necessary between them. These problems
have motivated development of alternatives to a conventional
implementation. Hence, a...
It has become customary in electrical engineering to think of
signal processing in terms of voltage variables to the exclusion of
current variables. This tendency has resulted in voltage signal
processing circuits such as voltage-controlled voltage sources
(VCVS) and voltage-mode operational amplifiers. However, the VCVS
operational amplifier has several limitations...
In the last few years, many schools and universities have incorporated personal
digital assistants (PDAs) into their teaching curricula, in an attempt to enhance
students' learning experience and reduce instructors' workload. One of the
most common uses of PDAs in the classroom is as a test administrator. This
study compared...
Most existing methods for generating individual task time estimates in production systems where jobs move through various manually operated workstations remain tedious and time consuming. For existing systems, average task times may vary considerably from prior estimates causing system inefficiencies, poor scheduling and poor planning decisions. Accurate and up-to-date estimates...
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J. DavidPorter
Most existing methods for generating individual task time estimates in
Certain applications have recently appeared in industry where a traditional bar code printed on a label will not survive because the item to be tracked has to be exposed to harsh environments. Laser direct-part marking is a manufacturing process used to create permanent marks on a substrate that could help...
Climate change affects the choice of land-use not only through its direct effect on the productive potential of land, but also through human actions that alter the landscape. In this dissertation, I estimate current climate's effect on the economic net returns to alternative land-use systems in the United States. Then...
Efficient and effective climate policies require cost estimates supported by empirical analysis at multiple spatial scales. Fine-scale spatial analysis of climate impacts for rural land markets represents a gap in the current climate change economics literature. In this dissertation I estimate relationships between climate, risk and parcel-level land values for...
Nitrification is a critical step in the global nitrogen cycle involving the biological oxidation of ammonia (NH₃) to nitrite (NO₂⁻ ) and then to nitrate (NO₃⁻). The first step in nitrification is carried out by NH₃-oxidizing bacteria (AOB) and archaea (AOA), and the second by NO₂⁻-oxidizing bacteria (NOB). In addition...
We developed a model to investigate the dielectric properties of the
BaTiO₃ − Bi(Zn₁/₂Ti₁/₂)O₃ (BT-BZT) solid solution, which is a relaxor ferroelectric and exhibits long range disorder. The model uses ab initio methods
to determine all polarization states for every atomic configuration of 2 x 2 x 2
supercells of...
The output characteristics of a conventional GaAs depletion-mode MESFET device have been investigated. One of the important parameters of the small-signal GaAs MESFET model, g[subscript ds] (output conductance), is shown to be frequency and temperature dependent. Variations in g[subscript ds] are a serious problem in many analog and digital circuits...
This study compares three approaches in the design of an autonomous machine listening agent that predicts harbor porpoise ultrasonic echolocation clicks in diverse noise environments. Considering the temporal variations of noisy coastal ocean soundscapes which the harbor porpoises inhabit, we propose a leave-one-day-out (LODO) cross-validation strategy in the training of...
The core area of a conventional CMOS digital gate
array consists of only one size of NMOS device and one
size of PMOS device. Both primitives have fixed minimum
channel lengths, and this has significantly impeded analog
applications. This work has shown that by forming series
and parallel interconnections between...
Full integration of CMOS low noise amplifiers (LNA) presents a challenge for low
cost CMOS receiver systems. A critical problem faced in the design of an RF CMOS LNA
is the inaccurate high-frequency noise model of the MOSFET implemented in circuit
simulators such as SPICE. Silicon-based monolithic inductors are another...
In this dissertation, two important current mode circuit design subjects have
been explored. In the first part, the switched-current circuit technique has been
investigated. The fundamental performance and limitations of this technique are
explored. One of the major limitations, the signal distortion caused by clock
feedthrough has been substantially reduced...
In this paper, an analysis of the clock-feedthrough effects in
switched-current (SI)' circuits will be presented. The clock-feedthrough
effects caused by the non-ideal characteristic of MOS
switches when they are turned off limit the accuracy of the analog
track-and-hold (T/H) circuits. A model to analyze and characterize this
effect is...
Advancements in the sophistication and complexity of modern electronic systems are creating a need for highly integrated systems with ever higher operational frequencies. The economical demands of these systems dictate that they be implemented using low cost fabrication technologies, such as digital CMOS. One of the major challenges facing circuit...
In recent years, there has been an extensive effort to develop low-cost implementations
of radio frequency integrated circuits for consumer applications. This thesis is a
research effort in the design and implementation of integrated RF CMOS Power Amplifiers
(PAs). A significant challenge in the implementation of RF CMOS ICs is...
The design considerations for fast-settling operational
amplifiers (opamps) differ significantly between sampled-data switchedcapacitor
(SC) and conventional continuous-time applications. In SC
circuits, the shape of the output voltage waveform of an opamp is of no
consequence provided that the output settles to within a specified
tolerance of its steady-state value prior...
The design and implementation of Switched-Current (SI) ladder filters is
described. SI filters require only a standard digital CMOS process and the power
supply voltage requirement is low. SI circuits also can be potentially operated at
higher frequencies than Switched-Capacitor (SC) filters due to the low-impedance
wideband nodes of the...
Multi-level decision feedback equalization (MDFE) is an effective technique to remove inter-symbol interference (ISI) from disk readback signals, which uses the simple architecture of decision feedback equalization. Parallelism which doubles the symbol rate can be realized by setting the first tap of the feedback filter to zero.
A mixed-signal implementation...
Decision feedback equalizer (DFE) is an effective method to remove inter-symbol
interference (ISI) from a disk-drive read channel. Analog IC implementations of DFE
potentially offers higher speed, smaller die area, and lower power consumption when
compared to their digital counterparts.
Most of the available DFE equalizers were realized by using...
Multi-level decision feedback equalization (MDFE) is an effective sampled signal processing technique to remove inter-symbol interference (ISI) from disk read-back signals. Parallelism which doubles the symbol rate can be realized by utilizing the characteristic of channel response and decision feedback equalization algorithm.
A mixed-signal IC implementation has been chosen for...
State departments of transportation, transportation consultants, and other transportation agencies are always in need of data that can be used to better understand how different modes of transportation use the road and highway systems. A variety of automatic data collection technologies have been used to gather these data including video...
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J. DavidPorter
State departments of transportation, transportation consultants, and other
Digitally-programmable filters have been an ongoing research topic for a number of years. The first such filters were FIR transversal filters using Charge-Coupled Devices (CCD's) and IIR recursive filters using switched-capacitor (SC) techniques. Although both techniques achieve excellent results, they require non-standard and/or additional IC fabrication steps. Low substrate doping...
Recently, switched-current circuits have received great
attention because they offer potentially better performance in terms
of speed, low voltage power supplies, and accuracy in mixed-mode
analog-digital signal processing. In this thesis, the distortion
characteristics, DC offset and AC gain errors induced by the threshold
voltage, channel width, channel length, and...
Natural resources play a crucial role in human society by providing both market value and non-market value. Effective management of these resources is necessary to achieve a balance between economic value and other non-market benefits. Econometric studies focusing on natural resource management help us understand the costs and benefits of...
The use of high throughput molecular methods that allow for the study of bacterial communities in environmental samples is commonplace in microbial ecology. Until recently, fungal community ecology has
focused on isolation, collection of sporocarps, or collection of ectomycorrhizal roots. The techniques used to extract and amplify DNA from environmental...
Location theory is a well-established and active research area. The main objective in location theory is to find the best locations for facilities to meet supply and demand constraints and minimize total cost. The median problem (also known as the 1-median problem) is a special case in location analysis that...
Deep Learning methods have been gaining a lot of significance for various Biomedical applications for diagnosing several types of diseases. Two applications considered here are: 1) Diabetic Retinopathy Detection and 2) ECG signal Classification (or Arrhythmia Detection). Diabetic Retinopathy (DR) is a major cause of blindness in Diabetic patients, and...
Forests are highly valuable resources providing both timber as well as many non-use values like habitat for various endangered and threatened species, carbon sequestration, and recreation, to name a few. Given that there are 765 million acres of forestland in the United States, almost 60% of which are privately owned,...
Forests provide a wide range of timber and non-timber products along with providing a range of ecological services and support for biodiversity. Climate change poses various risks to forest health, as it can disrupt tree growth functions and trigger natural disturbances that increase tree mortality. In recent decades, altered disturbance...
The CMOS two-stage Operational Transconductance Amplifier (OTA) has been a key enabler for mixed-signal IC design for nearly four decades . This research focuses on a modified two-stage CMOS OTA that features load-pole cancellation (LPC); i.e., the resulting architecture is essentially a two-stage CMOS OTA with no load capacitance. The...
Using summertime housing transactions data of 3,309 parcels from multiple years in Eugene-Springfield, OR, we present a hedonic price model to estimate the influence of the urban heat island (UHI) effect on housing prices in this metropolitan area. By taking advantage of the inherent random nature of summertime weather observations,...
This thesis uses a hedonic price model to estimate the value of water for irrigation in Deschutes County, Oregon. The analysis uses a dataset comprising information on 2,274 agricultural parcels across the County. Uniquely, the analysis successfully utilizes assessor-determined real market values in the place of actual land sales. A...
After a mobile communication device (MCD), such as a smartphone or tablet, has been sold to the public, the customer may find that there is a defect. Each MCD is sold with a warranty that covers the repair of manufacturing defects and is supported by the MCD manufacturer. A third...
The frontlines of climate change adaptation will occur in rural, impoverished regions of the world where households engage in climatically dependent livelihoods, such as peasant agriculture or pastoralism. As changing climate and changing markets affect the suite of household livelihood assets (environmental, social, and economic) which enable a household to...
Following European-American colonization of North America and associated landscape changes, barred owls (Strix varia) underwent a dramatic expansion of their historical range. The barred owl expanded across the previously tree-less Great Plains that had limited their distribution, and into the forests along the west coast. In these western forests they...
The equation of state for a fluid described by the Weeks-Chandler-Andersen (WCA) potential was solved to determine at what pressures and temperatures the fluid will theoretically freeze. A Monte Carlo (MC) algorithm was used to sample a system of 256 spheres for a set of thermodynamic averages to locate and...
With increasing interest in current-mode analogue processing due to its high
performance properties such as speed, bandwidth and accuracy compared to voltage-mode
processing, new current-mode alternatives to various conventional circuit designs are
appearing. In this report, a novel circuit design to construct a fully-differential current-mode
operational amplifier ( OP-AMP )...
The gm/ID-based design of analog integrated circuits introduced in 1996 employs an empirical transistor sizing methodology using SPICE-generated lookup tables that enables good agreement between simulations and specifications. This thesis introduces a new SPICE lookup table that extends the gm/ID approach to the Miller pole-splitting frequency compensation of the classical...
This thesis reports on computational research in two different areas. I first discuss the Min-protein system found within Escherichia coli. Following this I discuss an extended investigation into improving free energy functionals that are used within Classical Density Functional Theory in order to model water. Chapter 2 examines the dynamics...
Clock-feedthrough effects, channel-length modulation and device mismatch are
the main causes of the inaccuracy of Switched-Current (SI) circuits. In this paper, these
non-ideal effects are analyzed. A high-performance current mirror, namely regulated
cascode current mirror, which eliminates drain voltage variation problem is introduced.
By using this current mirror as a...
As Si MOS approaches its maximum limits in speed and bandwidth, new
devices are desired to meet the needs of high speed communications and signal
processing. A device that exhibits superior performance to Si MOS, BJT, and
GaAs technology is the HEMT (high electron mobility transistor).
The HEMT offers superior...
Private forest landowners can adapt to climate change by altering their timing and intensity of harvests, by changing thinning or fertilizing activities, and by altering the tree species growing on their land. The well-being of humans is closely tied to the ecosystem services that forests provide as both market and...
Stacked sheets of polyethylene terephthalate andpolystyrene provide a means
for recovering projectiles travelling at hypervelocities. The transparency of these
multiple diaphragms is utilized so that light generated from hypervelocity impacts
can be studied.
A method for gathering visible as well as ultraviolet light from less
transparent polymer foams has been...
Radio frequency identification (RFID) has long been regarded as an automated data collection technology that promises solutions to inefficiencies found in supply chains such as “just-in-case” inventory stock, inventory obsolescence, stockouts, and theft. However, the disappointingly slow return on RFID investment has forced companies to examine and redefine RFID initiatives....
Private forest owners face an increasing risk of economic damage from extreme wildfires as the climate becomes warmer and drier. This thesis empirically estimates the influence of climate on private forest owners’ management decisions using plot-level data in the Pacific states of the U.S. Econometric models are specified where the...
Transportation systems need to get better by moving ever more people while consuming ever fewer resources. To build better transportation systems, planners need an accurate understanding of how people exercise mobility and tools to apply that understanding to the transportation system. Such an understanding can come through the development of...
Single Point Incremental Forming (SPIF) is a forming process in which a fully clamped sheet is formed by a hemispherical ended tool that moves along a predefined 3D toolpath. The sheet is formed in a series of local deformations to reach its desired shape. Double Sided Incremental Forming (DSIF) includes...
Climate change has the potential to accelerate many forms of human migration and mobility, yet almost all of the key migration outcomes of interest are determined predominantly by governance, or the norms, laws, and institutions involved in the coordination of human society. These outcomes include the decision whether or not...
Nucleic acid estimates in tissues of marine macrophytes with the fluorochromes Hoechst 33258 and ethidium homodimer were severely impaired by high concentrations of interfering compounds. The isolation and extraction techniques used pointed towards compounds of low molecular weight and of polar characteristics that were insensitive to organic solvent extraction and...
The use of mobile bar code scanners is expanding to markets beyond popular manufacturing uses, such as healthcare, environmental testing and professional services. The successful interaction of users with mobile bar code scanners is of great importance from a business and technology perspective as well as from the user standpoint....
The operational transconductance amplifier (OTA) is a fundamental building block in analog and mixed-signal systems. This research describes a process-, voltage-, and temperature- (PVT) insensitive low-voltage tracking RC compensation scheme considered for two-stage CMOS OTAs, which cancels the pole due to the load capacitance using a Miller zero generated by...
Natural disasters are an increasingly costly and frequent occurrence globally and in the United States (IPCC, 2012; IPCC, 2014; Berlemann & Steinhardt, 2017). Discrete disaster events, such as coastal flooding, have been shown to be push factors in temporary and long-term migration (Black et al., 2013). Policy efforts to adapt...
This thesis will examine the model and design technique of a self-contained analog
CMOS Phase-Locked Loop. This system has an adaptable filter and demodulator for an
oscillating frequency of up to 1000 KHz and it is programmable by means of an external
resistor and capacitor. The first topic to be...
Stock loss and out-of-stocks are outcomes of poorly designed inventory management systems and can lead to significant revenue losses. Inventory management systems (IMS) based on radio frequency identification (RFID) have the potential to minimize these losses if they are properly designed and deployed. However, the placement of RFID readers to...
The characteristic of the subthreshold current in a
GaAs MESFET exhibits a negative exponential function with
Vgs. After studying the behavior of this current in this
region over a range of temperature and drain bias voltages,
a subthreshold current model was developed. The model was
implemented in a circuit simulation...
A MOS biquadratic (biquad) filter employing the switched-current technique is
reported. The circuit uses current-mode processing which can offer wide
bandwidth, low voltage operation, and can be implemented with standard CMOS
technology. Examples of lowpass, highpass, and bandpass filters are given
which illustrate the synthesis procedures and the versatility of...
A frequency compensation technique for increasing the
settling speed of two-stage operational amplifiers used in
switched-capacitor applications has been developed. By
properly decompressing the pole-zero doublet to form a
three-pole one zero system, the settling speed is increased
up to 50 percent as compared to the optimized two-pole
system.
The market for Wireless Local Area Networks (WLANs) has experienced tremendous growth over the last few years and this trend is expected to continue in the future. This growth is due to the fact that wireless LANs provide several benefits including mobility, efficiency, and accuracy. In addition, the cost of...
The ability to integrate designs from board level, multi-chip modules to single process solutions is highly attractive in today's PC multimedia industry. Saving board area and chip count will decrease the production cost of personal computing hardware and increase profitability. The ability to integrate analog circuit capability and it's reference...
Metal organic frameworks(MOFs) are a class of crystalline materials utilized in gas storage, chemicalsensing, and other engineering applications. Recently chemists have begun synthesizing MOFs withmoving parts in order to further these applications. A wide array of dynamic MOFs have been created andtheorized. Among them is the interlocking of a ring...
Small amounts of carbon from glucose and leucine added at natural
concentrations to seawater were biologically transformed to higher
molecular weight (MW) dissolved materials which persisted through six
months of incubation. These materials were resistant to biological
utilization: only 1 to 17% of the higher MW carbon was respired when...
In the case of lake management for recreational use, policy makers often face a balancing act. They must maintain both the ecological quality of sites and the welfare of recreationists. In Wisconsin's Northern Highland Lake District, recreational boaters inadvertently transport aquatic invasive species between lakes. Economic models of boater demand...
Changes to disturbance regimes resulting from shifts in forest management practices have created novel landscape conditions in the Pacific Northwest (PNW). I analyzed the implications of changes to landscape conditions caused by forest management for the spread of a native root disease: black stain root disease (BSRD) of Douglas-fir. BSRD...
Sensor system plays an important role in connecting everything including human body to the electrical information systems that we have built and that we are going to build, to make the world more intelligent and efficient. One of the key propulsive forces behind these emerging techniques is CMOS scaling that...
The motor protein dynein is responsible for cellular processes such as axonal transport and cell division by delivering vital information along the microtubule track. A failed delivery can cause severe damage to the cell’s functionality and lead to neurological diseases. Despite dynein’s rich history in cellular research, the mechanism of...
Sagebrush steppe ecosystems in the Great Basin have become increasingly threatened by the proliferation of cheatgrass (Bromus tectorum L.), an invasive annual grass. Diverse sagebrush and perennial bunchgrass landscapes can be converted to homogenous cheatgrass grasslands mainly through the effects of fire. Although the consequences of this conversion are well...
Nowadays, wireless communication systems use high-order quadrature amplitude modulation (QAM) together with orthogonal frequency-division multiplexing (OFDM) to increase the link capacity and robustness. These signals always have large peak-to-average power ratio (PAPR) and require power amplifiers (PAs) achieve both high efficiency and linearity simultaneously. For the efficiency, the complementary metal...
In this work we introduce some basic concepts within homotopy type theory (HoTT), a proposed alternative mathematical foundation to classical set theory. In particular, our discussion revolves around the Axiom of Choice (AC). In Part I, we introduce the classical AC and some of its most important equivalents. In Part...
Shocked porous granular material experiences pressure dependent compaction. D. John
Pastine introduced a model in which the degree of compaction is dependent on the pressure induced
by the shock wave, the shear strength of the material, and the distribution of void sizes. In the
past, the model could only be...
Computational statistical mechanics leans heavily on the class of Markov Chain Monte Carlo Algorithms. Many such algorithms exist, and simulations can run for several weeks, making the selection of algorithms a difficult, but critical task. In this work, we introduce a benchmark system of two quadratic wells with an analytical...
This dissertation reports on the computational physics research in the area of
inhomogeneous fluids. I first discuss the theory background for this work beginning
with water, which is important for the two published articles that are presented in
this work (Chapters 5 and 6). Next, I give a brief overview...
The purpose of this study was to understand the vulnerability and adaptive capacity of shellfish stakeholders in the Pacific Northwest who are adapting to ocean acidification (OA). This study developed a geovisualization tool of existing environmental data for assessing species-specific risk profiles to OA (based on their exposure and sensitivity),...