VictorJuiz/thesis huggingface dataset:
Signal preconditioning using feedforward equalizers in ADC-based data links [electronic resource]

As the data rates for high-speed wireline transceivers continue to increase, intersymbol interference (ISI) due to channel loss is becoming more pronounced and multiple techniques have been suggested to address this issue. One technique that has recently been gaining popularity is the ADC-based receiver. In ADC-based receivers, a digital feedforward equalizer (FFE) is used in conjunction with a decision feedback equalizer (DFE) to equalize the channel and recover the data. However, in order to recover the data with a high fidelity, a power-hungry ADC is needed to digitize the signal. Recent work has shown that an analog receive-side FFE (RX-FFE) prior to the ADC can reduce the required ADC resolution while achieving the same BER. In order to obtain a net improvement for the system, the RX-FFE must be implemented with low power consumption, low noise, and small chip area. In this thesis, an RX-FFE is demonstrated that meets these requirements and outperforms state-of-the-art designs. The RX-FFE is constructed entirely with low-noise and power-efficient analog-inverter transconductors and capacitors, avoiding the use of area-intensive inductors. The delay element is implemented as a single-path Pade-inspired delay shown to be equivalent to the first-order Pade delay in terms of RX-FFE performance. The proof-of-concept RX-FFE is demonstrated to reduce the signal dynamic range by 2x resulting in a 1 bit ADC resolution relaxation. The total power consumed is less than 26 mW with less than 0.62 mVrms output noise for all coefficient values and an area of only 0.003 mm^2 in 40 nm CMOS.

Keywords: Electrical Engineering.
Advisor: Murmann Boris primary advisor. Thesis advisor
Horowitz Mark (Mark Alan) advisor. Thesis advisor
Narasimha Madihally advisor. Thesis advisor
Signals or substitutes? Why economic sanctions undermine threats of force [electronic resource]

This dissertation investigates how the choice to use economic sanctions undermines threats of force. When faced with a crisis, leaders must choose among a menu of coercive strategies, and the choice of strategy conveys information about the leader's resolve. While some scholars and policymakers look to sanctions as tools for escalation, I argue that sanctions are poor signals of resolve for three reasons. First, sanctions have become attractive instruments for addressing low-level disputes where the use of force would be excessive. Second, sanctions exact pain on opposing states and can be used to ameliorate audience demands to ``do something" in crises where leaders are unwilling to fight. Third, since leaders have the option of directly threatening force, targets should expect the most resolved leaders to do so, and doubt the resolve of leaders who initially apply sanctions as an alternative strategy. This dissertation consists of three papers to support this argument, utilizing formal theory, quantitative analysis, qualitative historical study, and survey experiments to demonstrate why the choice to use sanctions signals a lack of resolve to fight.

Keywords: Political Science.
Advisor: Schultz Kenneth A. primary advisor. Thesis advisor
Fearon James D. advisor. Thesis advisor
Tomz Michael advisor. Thesis advisor
Simulation and computation of human and camera image systems [electronic resource]

Image systems capture, encode, analyze and reconstruct the information in the visual environment. Most image systems focus on light that is visible to humans with wavelengths ranging from 400 to 800 nm. Though the precise design and capabilities of different types of image systems vary widely, the ultimate goal for the image systems are similar: capture and estimate information in the environment. As Hermann von Helmholtz mentioned in 1857, the sensations of our nerves of sense are mere symbols indicating certain external objects. Bearing this in mind, we can revisit a series of image system problems from the perspective of how the system use the symbols to infer the external objects. In this dissertation, I use simulation and computation methods to address different backward estimation problems for imaging systems. I apply these methods to study two image systems: the human vision system and the consumer digital camera. Although the combination of computation and simulation methods may generate different algorithms and models for each image system, I believe the methodology can be generalized across many types of image systems.

Keywords: Electrical Engineering.
Advisor: Wandell Brian A. primary advisor. Thesis advisor
Farrell Joyce E.
Wetzstein Gordon advisor. Thesis advisor
Simulation of dusty plasmas and characterization of their effects on irregularities in the upper atmosphere [electronic resource]

Earth's atmosphere is a complex system composed of different layers of gas surrounding the Earth. Approximately between 50 and 1000 km above Earth's surface, solar radiation ionizes the gas to from a region of plasma in our atmosphere known as the ionosphere. Dynamics in the ionosphere are driven by a number of mechanisms. The predictable portion of the ionosphere is made up of three layers that shift in height and width depending on the time of day and the solar activity. In addition, the ionosphere hosts a number of transient non-dusty and dusty plasma irregularities that can affect the dynamics of the ionosphere. Understanding and predicting the dynamics of these irregularities is important in properly communicating between ground systems and space satellites because the ionosphere lies directly between these two. While non-dusty ionospheric irregularities have been studied for many years, the dust component in ionospheric phenomenon is only beginning to be considered, even though dusty plasma dynamics are far more complex to understand and predict. In order to better mitigate communication error in the ionosphere, a deeper understanding of the physics and dynamics of dusty plasmas is required. This thesis describes the simulation of dusty plasmas in ionospheric phenomena, namely polar mesospheric summer echoes (PMSEs) and meteors. The simulation methods utilized are a 1-D (PMSE) and 2-D (meteor) particle-in-cell (PIC) simulation. The simulations incorporate additional models for simulating the composition and growth of dust particles, the charge attachment of plasma particles to dust particles, and the collisions with neutral particles in the ionosphere. The PMSE simulation results demonstrate that presence of dust particles can lead to the development of the ice-plasma growth instability, which can lead to the development and detection of sharp small-scale structures as seen in PMSE rocket and radar measurements. In addition, the meteor simulation shows that the presence of dust during meteor expansion can reduce the overall diffusion rate of the meteoric particles and extend the detection lifetime of the meteor. These meteor simulation results will aid in explaining the detection of long duration meteor trails. The two simulations presented in this thesis are only a first step in exploring the effects that dusty plasmas can have on irregularities in the ionosphere. Understanding how dust can alter the dynamics of ionospheric irregularities will assist in reducing the noise and error when communicating through Earth's ionosphere in the future.

Keywords: Aeronautics and Astronautics.
Advisor: Close Sigrid
Cantwell Brian advisor. Thesis advisor
Lele Sanjiva K. (Sanjiva Keshava)
Single antenna null-steering for GPS & GNSS aerial applications [electronic resource]

As the utility of the Global Positioning System (GPS) and other Global Navigation Satellite Systems (GNSS) continue to pervade -and upgrade- our daily activities, our increased reliance makes us more vulnerable to the inherent weaknesses of GPS. The incredible faintness and unencrypted nature of the GNSS signal exposes it to both unintentional and intentional overwhelming, via mechanisms such as interference, jamming and spoofing (the broadcast of counterfeit GNSS signals intended to deceive a GNSS receiver). However some may argue that despite the great risk, the probability of a jamming or spoofing event is thankfully low. The argument may continue, that correspondingly few resources should be dedicated to protect against a low probability event. I attempt to resolve the tension between these high risk yet low probability scenarios by establishing antenna designs that provide protection while exploiting existing infrastructure and equipment, thus requiring minimal additional resource dedication. This thesis will start with an introduction of a low complexity mechanism for generating radiation pattern nulls and beams with a single antenna, without requiring any additional hardware or signal processing blocks beyond those already inherent to GNSS receiver systems. I will describe the basic mathematical model that underlies this mechanism and share simulation results. I will then introduce two applications of this mechanism: single antenna interference/jam suppression and single antenna spoof detection. Results from simulations and two field trials will be presented: one with a software implementation using a software defined radio, and the other with a hardware prototype implemented in off-the-shelf components using a standard GPS receiver. Results show about 15 dB of interference/jam suppression and robust spoof detection, when the threatening signals originate from below the horizon of the GNSS antenna, making aerial platforms an ideal application.

Keywords: Electrical Engineering.
Advisor: Enge Per primary advisor. Thesis advisor
Lee Thomas
Walter Todd advisor. Thesis advisor
The social, economic and cultural dimensions of bushmeat in Yaounde, Cameroon [electronic resource]

Urban bushmeat demand may now account for the majority of wild meat consumed in Central Africa, posing environmental, health, and economic dilemmas. The bushmeat trade represents a complex and dynamic interaction of cultural, political, socio-economic, and status-seeking behaviors that I investigate in this dissertation through interdisciplinary inquiries framed in political ecology, social capital theory, and grounded theory. The study took place in a major Central African city: Yaoundé, Cameroon. A census of profiles and sourcing relationships between Yaoundé's 211 bushmeat-selling restaurants, street stalls and hotels, 13 open bushmeat markets, and rural bushmeat source points revealed a decentralized trade, with the exception of a centralized primary market. Yaoundé's thriving open bushmeat markets circulated ca. 660 - 1320 tons of bushmeat per year, generating ca. US$ 4.4 - 8.8M annual gross revenues. Restaurant, street stall and hotel bushmeat sales accounted for US$ 1.8M annual gross revenues. Primary market sales data for 4112 purchases over 12 months documented over 24 taxa sold in the primary market, including rodents (31% of carcass sales), ungulates (17%), primates (13%), scaly anteaters (12%), and reptiles (11%). While women were the primary sellers at low-priced, high volume street stalls and bar-restaurants, men were associated with the sale of high-priced, endangered species at restaurants and hotels, reflecting distinct gendered approaches to the trade. Ethnography in the primary market revealed that more-educated traders and sellers are relegated to the trade but would prefer other work, while less educated marketers with ethnic ties to forest zones found bushmeat trading an appealing option. Participant observation and interviews with 211 consumers revealed that eating bushmeat in Yaoundé appears to reaffirm cultural and kin connections for people originating in forest zones; buffer food security needs for lower economic classes; and meet luxury and social status seeking desires for high economic-status consumers of endangered species. Combined, these results reveal possibilities for reshaping a regulated trade that would incorporate the suite of livelihood and socio-cultural needs currently met through consuming and selling bushmeat in urban Central Africa.

Keywords: Anthropology.
Advisor: Jones James Holland primary advisor. Thesis advisor
Curran Lisa Marie
Durham William H. advisor. Thesis advisor
Social meaning in linguistic perception [electronic resource]

As individuals position themselves and others in the social landscape, they use language to convey and to understand the social meanings indexed by linguistic forms. Research taking social meaning as central to the study of linguistic variation has shown that linguistic features are deployed as components of styles, or clusters of features, and speakers use these styles to enact particular personae, or social types. Though a majority of studies in this realm have focused on speakers' production of styles, semiotic links between styles and personae are formed, reproduced, and reinterpreted in the interactional space between the speaker, who produces these styles, and the listener, who construes them. This dissertation focuses on the listener perspective, exploring the cognitive underpinnings of links between social meaning and linguistic variation at various levels of awareness. This dissertation provides evidence that social meanings and linguistic features are inextricably intertwined in listener perceptions. The same links between a single linguistic feature (the backing of the TRAP vowel) and its social meanings are examined in four paradigms that range from more controlled to more automatic perceptual behavior, asking (1) how persona-based information can affect linguistic categorization, (2) when in processing links between social and linguistic information become evident, (3) how these links can affect memory (and thus, cognitive representations), and (4) the relation of all of these processes to explicit social evaluations. At all of these levels, I show that social meanings crucially shape the way that linguistic perceptions unfold. Specifically, I argue that the constructs of social personae are integral to the way that language is interpreted online, in interactions, advocating for movement beyond the heavy focus on macro-social information in studies of sociolinguistic perception. Further, I demonstrate gradience in listener awareness of feature-meaning links below the level of consciousness, showing that explicit social evaluations of language do not straightforwardly predict effects in more implicit perceptions.

Keywords: Linguistics.
Advisor: Eckert Penelope primary advisor. Thesis advisor
Podesva Robert primary advisor. Thesis advisor
Sumner Meghan advisor. Thesis advisor
Soil microbial community responses to long-term multifactorial global change in a California annual grassland ecosystem

Soil microbial communities (SMCs) are important regulators of biogeochemical cycles and plant nutrition in terrestrial ecosystems, but the diversity, composition, and function of SMCs are expected change in response to anthropogenic global change. While field-based, manipulative global change experiments have helped to build a nuanced understanding of plant community responses to multiple interacting environmental changes in a variety of ecosystems, relatively little research has investigated the response of SMCs to similar conditions. To this end, we used next-generation DNA sequencing to assess the soil fungal and bacterial communities in the bulk soil (0–7cm depth) of the Jasper Ridge Global Change Experiment: a full-factorial global change experiment that has tested two levels of nitrogen deposition, atmospheric CO2 concentration, temperature, and precipitation in a California annual grassland since 1998. Of the four global change treatments, nitrogen deposition had the strongest effect on the composition of SMCs, and also explained the most variation in fungal richness. Although all individual treatments had significant effects on SMC composition and diversity, treatment interactions in this experiment were infrequent and could only be identified at finer taxonomic scales in the bacterial community. Furthermore, the best covariates for most SMC composition and diversity were usually not the global change factors themselves; SMC properties could be better explained by soil chemical properties that were, in turn, affected by a global change treatment. In particular, fungal and bacterial community composition were the best covariates for each other, suggesting that despite differential effects of global change on fungal and bacterial communities, as a whole their relationship is resilient to global change. Finally, we found a significant decrease in the relative abundance of arbuscular mycorrhizal fungi under elevated CO2, which has never been described in the literature. Our results support the hypotheses that increased nutrient inputs can cause strong shifts in SMCs in grasslands, and that the ultimate effect of global change factors on SMCs is mediated by changes to the local soil environment.

Keywords:  Department of Biology
biology
microbial ecology
global change
soil microbial communities
arbuscular mycorrhizae
nitrogen limitation
elevated CO2
warming
precipitation
grassland
Jasper Ridge Global Change Experiment
Thesis
Advisor: Peay Kabir
Dirzo Rodolfo
Some finiteness results for groups of automorphisms of manifolds [electronic resource]

We prove that in dimensions not equal to 4,5,7 the homology and homotopy groups of the topological group of diffeomorphisms of a disk fixing the boundary are finitely generated in each degree. The proof uses homological stability, embedding calculus and the arithmeticity of mapping class groups. From this we deduce similar results for the homeomorphisms of R^n and various types of automorphisms of 2-connected manifolds.

Keywords: Mathematics.
Advisor: Galatius Søren
Cohen Ralph L.
Wilson Jennifer C. H. advisor. Thesis advisor
Sound and vision [electronic resource] : sonic experience in Wordsworth, Blake, and Clare

This dissertation re-orients the study of Romantic poetry by advocating a shift in Romanticist critical discourse away from the visual sensorium and towards a focus on sound. I examine three major poets—William Wordsworth, William Blake, and John Clare—whose work has been critiqued, celebrated, or otherwise understood through a critical focus both centered on and shaped by tropes of visuality. An investigation of poetic sound, I argue, helps us understand the work of these poets on a more fundamental level. Sound was used by these writers to promote the aesthetic mode of experience over and against social and intellectual forces that threatened the essential freedom of the human imagination. In doing so, they were also writing against a millenia-old tradition in Western thought that privileged visual over audible experience.

Keywords: English.
Advisor: Greene Roland
Gelpi Albert advisor. Thesis advisor
Vermeule Blakey advisor. Thesis advisor
Sounding the nation [electronic resource] : dialect and the making of modern China

This dissertation argues that the concept of "dialect" was fundamental to the formation of modern Chinese nationalism and identity. I contend that elite and non-elite groups, inspired by diverse conceptualizations of nation, local place, and self, relegated China's myriad local languages to the status of 'dialect' -- a category that simultaneously webbed local communities to the broader concept of the Chinese nation, but also excluded them by placing them outside of the idealized form of "standard" Chinese. By tracing how the meaning of dialect was transformed by nineteenth-century Western missionaries, early twentieth-century artists and academics, and finally, the Nationalist and Communist governments, I show how Chinese—both as a language and as a national and ethnic moniker— was not just heterogeneous, but something that state-defined standards could not adequately capture.

Keywords: History.
Advisor: Mullaney Thomas S. (Thomas Shawn) primary advisor. Thesis advisor
Inoue Miyako
Lee Haiyan advisor. Thesis advisor
Sommer Matthew Harvey
Space environment effects on the gravity probe B satellite control system [electronic resource]

Gravity Probe B (GP-B) was a satellite-based physics experiment designed to test Einstein's General Theory of Relativity. Circling the Earth in a polar orbit, the spacecraft housed four spinning spherical gyroscopes and measured the inertial orientation of their spin axes. Based on the theory, two relativistic effects, the geodetic effect and the frame-dragging effect, were predicted to cause a drift of the gyroscope spin axes in perpendicular directions. GP-B made unprecedented measurements of both of these effects. The primary focus of this dissertation is an improvement to the GP-B spacecraft attitude estimation using an updated model based on the response of the control system to the space environment. Early data analysis revealed to 1% the influence of the geodetic effect in the motion of all four gyroscopes, but also illustrated the need to model and remove several systematic noise sources, in order to measure successfully the much smaller frame-dragging effect. Some disagreement in gyroscope drift rate estimates has been identified as a Newtonian torque, called the misalignment torque, and resulted from the interaction between electrical patches located on the gyroscope and housing surfaces. This torque caused a motion of the gyroscope spin axes that blended in with the science results, but that was modeled and removed from the data. This modeling required an improvement in satellite attitude estimation. The main contribution of the work described in this dissertation is to improve the spacecraft pointing knowledge, in order to model more effectively the misalignment torque disturbance. By modeling the response of the vehicle to the space environment, it was possible, in many cases, to reduce the pointing estimation uncertainty by a factor of two. Much of the improvement in satellite pointing estimation came from an improved understanding of the thermal space environment, specifically the thermal cycles that caused much of the vehicle motion that required additional terms in the attitude estimation model. The improvements made using the new model were used to generate a new time history of vehicle pointing for use in the GP-B data analysis.

Keywords: Aeronautics and Astronautics.
Advisor: DeBra D. B. (Daniel B.) primary advisor. Thesis advisor
Close Sigrid
Everitt C. W. F. (C. W. Francis)
Rock Stephen