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Data Transport in an Integrated NGSO Satellite Communication and Radio Astronomy System
No full textAn integrated mega-constellation non-geostationary orbit (NGSO) satellite communication
and radio astronomy system (ISCRAS), was recently proposed in the literature as a new
coexistence paradigm. We consider ISCRAS and focus on radio astronomical observation
(RAO) data transport from the RAO-conducting satellites (called source satellites) to the
ground gateways where each gateway is directly connected to a certain number of satellites
(called destination satellites). This transportation of RAO data is an important problem
and an existing work addressed it by applying a linear programming optimization based
algorithm. However, the computational complexity of this algorithm is quite high which is
exacerbated by the need to re-compute the algorithm frequently due to the time-varying
characteristics of the RAO-conducting satellites, the Earth stations, and the RAO region.
To address this high complexity issue, we develop a low-complexity RAO data transport
algorithm. In addition to the static spectrum resource constraint scenario considered in the
existing work, we introduce a dynamic spectrum resource constraint scenario to exploit the
knowledge of the satellite communication system (SCS) traffic statistics. We also present
a modified version of the optimization based algorithm in the literature for the dynamic
resource constraint scenario. In addition to the number of inter-satellite link (ISL) hops as
the RAO data transport cost metric, we also evaluate the metric of the sum of the squared
ISL hop distances which reflects the transmission energy cost. Furthermore, computational
complexity analysis and data transport costs of the algorithms are presented. Our results
show that the proposed algorithm yields several orders of computational complexity saving over the existing method while incurring a modest increase in the data transport cost.
Our proposed dynamic resource constraint scenario provides plausible reduction of the RAO
data transport cost. Next, we introduce a generalized ISL connection model which extends
the existing approach of adjacent-only ISL connections to include non-adjacent ISL connections. This model is implemented with an upper limit on the ISL distance which can be
adjusted for performance tradeoffs. Next, we develop analytical expressions to study two
impacts of satellite dynamics on the RAO data transport. The first one concerns with the
beam misalignment of individual ISL hops. The second one corresponds to whether destination satellites move outside the gateway coverage during the end-to-end delay interval of a
data packet transport. Furthermore, we introduce delay, energy, and spectrum usage performance metrics and evaluate them to yield performance tradeoff guidelines. A simplified data
transport path model is also presented to facilitate analytical performance evaluation and
initial system design settings. Then, we present a new RAO data transport design which
incorporates system dynamics and desired performance tradeoffs
Ambivalent Pleasures: Pleasure, Desire, Authenticity, and the Production of Value in Online Disability Cultures
No full textThis dissertation, “Ambivalent Pleasures: Pleasure, Desire, Authenticity, and the Production of
Value in Online Disability Cultures,” examines how discourses of “desirable disability” manifest
in cultural productions and Internet publics. I trace the circulation and intensification of this
discourse in popular culture, exploring the neoliberal commodification of identity politics that
occurs and, concomitantly, is contested, as a result of this discourse. I undertake this analysis
through a combination of discourse and textual analysis, examining a range of audiovisual
material from the last ten years including independent film— The Sessions (2011), streaming
television—Netflix’s Special (2019-2021), and social media—Jillian Mercado’s self-presentation
on Instagram. Alongside neoliberal attempts to commodify desirable disability, I analyze the
complex relations between pleasure, desire, and authenticity that undergird desirable disability.
Building on a foundation of crip theory, critical disability methodology, and critical/disability
media studies, this dissertation asks the following questions: first, how is desirable disability
visualized and narrativized across intersections of race and gender; second, how do the
sociotechnical systems in which desirable disability is visualized and narrativized reproduce
those same oppressive processes that disability activism works to actively resist? In the case of
disability, the language and practices of desire are acts of resistance. They are a reaction against
medical and scientific regimes of cure, which position disability as undesirable. However, even
when advancing the notion of desirable disability is a rejection of a model of cure—and thus, is a
model for world making and knowledge production— this embrace of desirable disability online
invites economies and structures of desire that allow for value extraction and processes of
neoliberal logic and communicative capitalism, which effect different bodies unequally in
differing historical and cultural contexts. These are the contradictions this dissertation
scrutinizes. As radical method and in its activist form, desirable disability seeks to capacitate the
disabled body. However, practiced within culture industries, it also allows for the
commodification of labor and lived experience, giving rise to those same ableist—and racist and
misogynistic—ideologies that disability activism strives against. This dissertation seeks to
critically examine these structures of power-knowledge, sketching out these oppressive specters
in the service of imagining more just worlds, bearing in mind the centrality of medium
affordances and limitations that is key to this project, and seriously considering the cultural work
of disability and disabled people within and across media industries. Most importantly however,
I aim to demonstrate there is no single discourse of disability and desire. I take up a constantly
modulating constellation of politics, culture, and technology that work upon publics differently,
to produce crip imaginings of the future
Murphy: a Framework for Identifying Risks for Collaborative Systems During Requirements Engineering
No full textA risk is an undesirable event that can result in mishaps if not identified early on during
requirements engineering adequately. However, requirements engineers may not always be
aware if important/critical risks are ignored. For instance, in building a smartphone appli-
cation to help blind people navigate indoors, it may not be too evident to the requirements
engineer that a blind person may not be able to walk in a straight line, or may not be able
to turn at a right angle at the right spot, etc. Similarly, for an Autonomous Vehicle run-
ning on the Autodrive System (ADS), it may not be too evident that the driver may ignore
instructions from the system or the ADS may not be able to identify obstacles accurately
or may not be able to identify any obstacles at all. These are a few examples of many such
risks that can occur with collaborative systems, where the (semi-)automated systems and
the agents in their environments need to collaborate with each other to achieve the intended
goals of the stakeholders. However, identifying risks can be challenging, and there is a lack
of systematic risk identification and analysis approaches to identifying risks for collaborative
systems.
This dissertation presents Murphy and Murphy+G frameworks for identifying and analysing
risks. Murphy is an Ontology-based framework that adopts the Reference Model to sys-
tematically identify risks by generating a Risk Analysis Graph (RAG). Murphy+G is a
goal-oriented framework that extends Murphy Framework for identifying risks, facilitating
the requirements for engineers/developers to devise risk-mitigation strategies by adopting the
NFR Framework and extending it with the Reference Model to identify risks and perform
risk analysis qualitatively.
We propose five main technical contributions: 1. The domain-independent, activity-oriented
ontology and processes for both Murphy and Murphy+G are presented explicitly for de-
scribing categories of essential concepts and relationships and constraints related to agent,
action, risk, requirements, specification, domain, etc. The ontology ensures that there are
no omissions and commissions of risks. 2. An Augmented Reference Model is obtained by
adopting the Reference Model and extending it with risks to perform risk generation and
identification. 3. Rules for systematically generating risks and thereby facilitating the devel-
opment of risk mitigation strategies later. 4. A Risk Analysis Graph (RAG) shows a bigger
picture of all the risks possible for a requirement and its corresponding specification and
domain assumptions. 5. The (SIG-PIG)+ RM (Reference Model) graph, which considers
NFRs, identifies risks and corresponding mitigation strategies for achieving user goals by us-
ing the Reference Model. To see the strengths and weaknesses of Murphy and Murphy+G,
we have used the Murphy Assistant tool to identify a set of risks from a requirement. These
risks are categorized based on their criticality, and these results are compared against the
risks identified by students from team projects. We feel that the proposed framework helps
identify the most important and critical risks and devise risk-mitigation strategies for those
risks, which would help users to avoid risks to some extent and feel confident about using
the system
Left Orderability of Cyclic Branched Covers of Rational Knots
No full textA non-trivial group G is left orderable if there is a total ordering < on G such that g < h
implies f g < f h for all f, g, h ∈ G. In this dissertation, we study the left orderability
of the fundamental groups of cyclic branched covers of the 3-sphere, S3, branched over
rational knots. Specifically, the focus is on the three parameter family of rational knots
C(2p, 2m, 2n+1) in the Conway notation. This study is motivated by the L-space conjecture
of Boyer-Gordon-Watson, which states that an irreducible rational homology 3-sphere is an
L-space if and only if its fundamental group is not left oderable. A sufficient condition for
the fundamental group of the r-th cyclic branched cover of S3 branched over a prime knot
to be left orderable was given by Hu in [12]. As an application, Turner determined the left
orderability of the fundamental groups of the cyclic branched covers of the rational knots
C(2n + 1, 2, 2) for a positive integer n. In Chapters 2 and 3, we generalize Turners results
to the rational knots C(2p, 2m, 2n + 1) where p, m, n are integers
Evaluation of Consonant Error Patterns in Speech Perception and Production of Pediatric Cochlear Implant Users
No full textThis dissertation uses the framework of the speech chain to examine the associations between
perception/production and associated error patterns in children using cochlear implants (CIs),
children with normal hearing (NH), and children with NH listening to vocoder simulations (NHV).
Chapter 1 introduces background information on the populations represented by the three groups.
This chapter focuses on typical perception and production development and introduces the
challenges in evaluating perception and production patterns in children with hearing loss (HL).
Chapter 2 examines the association between consonant perception, production error patterns and
speech ineligibility in two groups of children using CIs: one group implanted at early ages using
newer CI technologies, and the other group implanted at later ages using older CI technologies.
Data from the Chapter 2 helps to establish the methodological basis for constructing a new
database described in the Chapter 3. Chapter 3 examines perception and production error patterns
in children using CIs who were implanted after 2010 using newer CI technologies in comparison
to NH and NHV control groups. Chapter 4 provides a general discussion that relates the findings
of these three studies.
Results from Chapter 2 indicate lower speech perception scores with a higher number and greater
variability of errors in the CI group implanted with older technologies compared to the CI group
implanted with newer technologies. Methodological limitations in the data presented in
Chapter 2 did not permit a direct comparison of errors in consonant production and perception.
The testing procedures developed in Chapter 3, which allowed for such comparisons, showed
that production and perception error patterns generally did not mirror one another. Although no
overall differences in mean error rate were observed between CI and NH groups, the error
patterns for individual consonants in these groups were different. Perception performance of
children in the NHV group was worse than in CI group suggesting caution is needed when
interpreting CI vocoder simulation studies in children. The results provide important clinical
information suggesting that intervention for children using CIs needs to consider how speech
perception confusions interact with the production errors in order to develop more effective
techniques for including them in clinical protocols
Evaluation of Engineered Microstructure Developed Using Interpenetrating Lattices Fabricated by Laser Powder Bed Fusion
No full textLaser powder bed fusion (LPBF) is one of the well-adapted additive manufacturing processes used
to fabricate near-net shaped complex metal parts with high accuracy. LPBF involves various
process parameters such as laser power, scan speed, scan strategy, hatch spacing, and layer
thickness, which significantly affect the properties of the fabricated parts. The microstructure of
LPBF parts can be controlled by selecting appropriate process parameters. However, achieving a
controlled combination of both coarse and fine grains has been a challenge due to rapid changes
in the thermal gradient. To address this challenge, this study introduces an innovative approach
using interpenetrating triply periodic minimal surfaces (TPMS) lattices. These lattices are
employed to control the percentage and distribution of both coarse and fine grains. However,
implementing the LPBF process to fabricate interpenetrating lattices presents various challenges,
including selecting suitable process parameters for designing and fabricating the defect-free parts.
Initially, a comprehensive investigation is conducted to understand the processing, structure, and
properties of bulk structures created using the LPBF process in a single metallic alloy.
Subsequently, different lattice designs, unit cell sizes, and fabrication strategies are examined to
achieve defect-free interpenetrating TPMS lattice parts. Finally, the appropriate process
parameters, interpenetrating TPMS lattice design, and fabrication strategy are optimized to create
parts with an isotropic microstructure. The parts with engineered microstructure exhibit a desired
combination of coarse and fine grains, leading to improved electrochemical and comparable
mechanical properties when compared to bulk specimens fabricated using LPBF
Remote Sensing Videography: Potentials, Methods, and Applications
No full textIn the last several years, new satellite sensors capable of capturing videos have been developed
and launched. Unlike satellite images, the temporal resolution of a satellite video is determined
by its frame rate. For example, the sensors onboard SkySat satellites can film panchromatic
videos at the 1-meter spatial resolution with a frame rate of 30 frames per second (fps), which
means the sensors’ temporal resolution is approximately 0.03 seconds. With the potential to
detect and tracking moving objects, satellite videography provides a new perspective for Earth
observation and enables important applications that may not be possible by using traditional
remote sensing images.
Moving object detection and tracking has been a hot topic in remote sensing. However, such
research using satellite video data have been scarcely investigated. The first objective of this
study was to utilize a satellite video to detect and tracking airplanes. To achieve this, two
different methods have been developed. The first method includes an Improved Gaussian-based
Background Subtractor (IPGBBS) algorithm for moving airplane detection and a Primary Scale
Invariant Feature Transform keypoint matching (P-SIFT KM) algorithm for moving airplane
tracking. The second method includes a Normalized Frame Difference Labeling (NFDL)
algorithm for moving airplane detection and a template matching with improved similarity
measures (TM-ISMs) for moving airplane tracking. The second objective of this study is to
achieve traffic monitoring with satellite video data, which involves moving vehicle detection and
tracking, vehicle motion property extraction, and traffic property extraction.
The performance of the developed methods for moving airplane detection and tracking were
compared with state-of-the-art approaches. Experimental results show that IPGBBS possesses
higher detection accuracy than state-of-the-art approaches, and NFDL exhibits the highest
detection accuracy. Moreover, TM-ISMs achieve notably higher tracking accuracy than TMTSMs. The developed method for traffic monitoring was tested on a satellite video of an urban
area and demonstrated high accuracy for moving vehicle detection and tracking, which
contributed to the effective extraction of both vehicle motion properties and traffic properties
Vatican Influence in the United States: the Roman Catholic Church’s Attempt to Retain Power in the U.S. Philippines
No full textThe United States prepared to extend its imperial conquests overseas after a century of land-
locked expansionism. Normally occupied with conquering continental tracts or exerting
influence in the Caribbean, the United States government opted to invest in the “Spheres of
Influence” concept reverberating around the Western powers. The Philippines now protected
America’s interests in the Pacific. It became evident that the Filipinos would not receive their
independence at this time, as the governments of Spain and the United States worked out a treaty
to transfer power. Yet the Roman Catholic Church, the largest landowner in the Philippines, still
held considerable power. the American episcopacy would have an opportunity to make an impact
on the future of the Philippines. Without official power in the government, the American bishops
needed to exert their authority in alternative ways. Contrary to previous claims of a decentralized
American episcopacy with individual bishops wielding disparate agendas, American bishops
were in fact unified within America prior to the Spanish-American War. This unification
occurred through their continuous subordination to Roman directives and through the protection
of the Church in the Philippines at the expense of America’s best interests. The Church’s attempt
to regain or exert temporal power over countries through treaties and negotiations emerges
regarding the agriculturally profitable friar-owned lands and the influence of the Catholic Church
on the Philippine islands
Coupling of Ionic and Electronic Processes in Lead Halide Perovskite Devices and Nanostructures
No full textLead Halide Perovskites (LHPs) such as Methylammonium Lead Iodide (MAPbI3) or Cesium
Lead Bromide (CsPbBr3) have garnered massive attention from researchers in photovoltaic, light
emitting, and other optoelectronic fields as an interesting class of materials with attractive
semiconducting and optical properties. Fabrication processes of LHPs are relatively simple
compared to conventional inorganic semiconductors and don’t require powerful or expensive
equipment which is promising for commercial development. However, they have shown
dynamic performance behaviors and instabilities that have yet to be fully understood. These
dynamic behaviors on the time scale of seconds have been attributed to their mobile charged
point defects redistributing themselves during device operation. The ions (or charged defects) act
as mobile intrinsic donors and acceptors that can be utilized in device operations. This thesis
discusses the physical origin that strongly couples the electronic and ionic transport of LHPs and
demonstrates devices that exploit and utilize this coupling. This coupling enables the dual
functionality of mixed halide solar cells to also act as effective light emitting devices. We also
demonstrate that utilizing extrinsic ionic salts such as lithium hexafluorophosphate (LiPF6) can
serve as sacrificial ions that help protect the bulk of the perovskite from fast degradation. We
studied the dynamic performance of LHP optoelectronic devices configured as perovskite lightemitting electrochemical cells (PeLECs) under various temperatures and conditions. We develop
novel equivalent circuit models to extract the diffusion coefficients and concentrations of
dominant ionic species at play in PeLEC devices in vacuum and dry air, in the dark or under
illumination, and at different temperatures. Activation energies of ionic species in PeLECs were
calculated by the temperature dependence of fitted parameters from diffusion elements in the
equivalent circuits used to model impedance spectroscopy measurements. This thesis advances
the knowledge and understanding of ion migration (or charged point defect transport) in LHP
devices and how it affects their performance
Essays on Hedge Fund Activism and Family Firm
No full textThis dissertation has two essays covering hedge fund activism and family firm.
In the first essay of my dissertation, I investigate how hedge fund activism reengineer corporate culture of targeted firms. By using culture measures based on the Q&A section
of earnings conference calls, I find that target firms emphasize building organizational
culture with better quality, more innovation, higher integrity, and growing respect after
activism. However, teamwork culture does not change. I also find that these positive
effects of activism on corporate culture are mainly driven by CEO turnover, especially if
incumbent CEOs are replaced by outsiders, not insiders. New outside CEOs are recruited
from firms with better culture and higher asset sales. Activist-appointed directors also
influence corporate culture by promoting outside CEO turnover. Target firms with positive cultural change improve their firm performance. Additionally, employees of target
firms perceive their firms’ culture as improved after activism. Overall, this study provides evidence of the importance of corporate culture as a source of gains from hedge
fund activism.
The second essay examines the extent to which founder-CEOs pay attention to stock
market signals in making their investment decisions. We find that founder-CEOs, on average, place significantly less weight on market signals than professional CEOs, without
compromising investment efficiency and firm performance. We employ decimalization as
an exogenous shock to show that the market premium due to enhanced liquidity is lower
for founder-CEO firms, consistent with founder-CEOs underweighting the incremental
information provided by a more liquid market. Further, we find that the weaker learning
behavior is more prominent if founder-CEOs possess more specialized skills and operate
firms with higher R&D intensity and greater operating cash flow volatility. We argue
that founder-CEOs’ superior skills and longer-term investment horizons drive this result. Price informativeness, CEO power, external monitoring, financing constraints, and
overconfidence do not seem to drive our findings