VictorJuiz/thesis huggingface dataset:
Design Techniques for Energy-Efficient, Low Latency High Speed Wireline Links

As data and computing systems get larger with more elements composing a single system, streamlined computation and data communication has put an ever-increasing demand on throughput of high speed SerDes. Industrial standards have responded to this trend by increasing the data-rate of chip I/Os, demanding doubling per-pin data-rate around every four years while the power budget remains the same. This implies that the energy efficiency of these links must improve all while being able to handle the harsher equalization environments seen at higher frequencies. To address the challenge of per-pin bandwidth, this thesis first presents various receive side equalization techniques used in a 60Gb/s non-return-to-zero (NRZ) link. In particular, a double data-rate (DDR) architecture uses current integration in several front-end equalization circuits, including the continuous-time linear equalizer (CTLE), feed-forward equalizer (FFE), and decision-feedback equalizer (DFE), demonstrated in a receiver frontend to achieve 60Gb/s operation with > 0.2 UI-timing margin at 1e-9 BER, while consuming 173mW. The same architecture was utilized within a complete non-return-to-zero transceiver with adaptive equalization achieving 60Gb/s with >0.3 UI opening at 10-12 Bit Error Rate (BER), while consuming 288 mW and occupying 2.48 mm2./nFurthermore, supporting this throughput in distributed system with a ubiquitous communication standard calls for links, which are able to quickly turn on and off and operate efficiently in low utilization modes while supporting capability for maximum throughput. This thesis then goes into an analysis of the requirements motivating our architectural and circuit level decisions for a burst-mode, energy proportional wireline link. To achieve energy proportionality, a 2-tap switched-capacitor transmitter with FFE equalization is presented that allows for a fully dynamic architecture operating at a nominal data-rate of 20Gb/s while maintaining energy-efficiency during both high and low link utilization. Additionally, a rapid-on/off voltage controlled LC oscillator uses resonant clocking to save power by directly driving the data-path capacitive loads all while improving overall latency, and a phase interpolator with a phase adjustable clock divider allows for the lowest achievable latency design for a 64:1 1-latch serializer implementation. The transmitter was taped out in TSMC’s 28nm GP process, and achieves 1.2ns startup time and 0.72-0.62 pJ/bit at 1-20Gb/s while occupying 0.19mm2.

Advisor: Alon, Elad
Nikolic, Borivoje
Measurement of Krypton Fission Product Yields from 14 MeV Neutrons on 238U

Precisely-known fission yield distributions are used to determine a fissioning isotope and the incident neutron energies in nuclear security applications. 14 MeV neutrons from DT fusion at the National Ignition Facility (NIF) induced fission in depleted uranium (DU) contained in the target assembly hohlraum. The fission yields of Kr isotopes (85m, 87, 88, 89, and 90) were measured relative to the cumulative yield of 88Kr. The fission gas was pumped from the target chamber, collected, and analyzed in the Radiochemical Analysis of Gaseous Samples (RAGS) diagnostic. Isotopes with half-lives ranging 8 s-9 hr can be measured. Kr fission yields have been measured both from the fission of DU in the hohlraum and DU doped into the capsule ablator. Since the mass of U was not known, the relative amounts of Kr isotopes were calculated and compared to existing fission product distribution tables./nIt was found that measurements can be performed with high precision for isotopes with half lives longer than 4 minutes. A more precise quantification of gas transport needs to be achieved to quantify isotopes with shorter half lives to a precision of the published tables.

Advisor: Morse, Edward
Scalable RF Receivers for Large Antenna Arrays

The ongoing exponential mobile traffic increase is continuing to push the requirements of wireless communication systems. Currently in dense urban areas the major limitation to the capacity of wireless links is interference between different users. Massive MIMO is a promising technology to address this challenge, where directional spatial beams are formed by an antenna array on a base station, each serving a different user. This concept is currently verified using commercial general-purpose analog hardware, with power consumption in the kW range for large arrays./nThis thesis focuses on energy-efficient RF receiver design for Massive MIMO systems. In order to be energy-efficient, the system requirements for a large antenna array receiver are different from a conventional single-antenna receiver. We use the fact that the noise of each receiver is uncorrelated across the array, so we can save power by using receivers with larger noise, while still meeting the link budget requirements. However, receiver linearity cannot be relaxed due to the digital beamforming used in the system./nTo address these challenges a novel RF receiver architecture is proposed, using a mixer-first approach with mixer switch resistance larger than 50 Ohm. Configurable mixer and baseband Gm sizes allow the receiver to trade noise figure for power consumption and use the same receiver for various array sizes and array-level noise specifications. Harmonic recombination is performed early in the signal path, enabling rejection of harmonic blockers up to -10dBm of power./nThis architecture was implemented in a first chip prototype. Scalable element noise figure results in sub-2.5 dB array-level noise figure with 16 to 64 antennas and <368 mW total power consumption, for a frequency range of 0.25-1.7GHz./nIn the second chip we perform an optimized design using the Berkeley Analog Generator (BAG). The proposed generator design methodology produces instances with optimum power consumption for a given noise figure specification. An instance of this generator is implemented in the chip, showing power consumption improvement of 50% and wider frequency range of 1-6GHz compared to the first chip.

Advisor: Alon, Elad
Pending Governance Challenges in the Mexican Oil Industry: A Case for Checks and Balances

This is a critical account of the regulatory framework governing Mexico’s upstream petroleum sector, as a result of the energy reform passed by Congress in 2013 and 2014. Despite the high expectations raised by the opening of the Mexican oil sector towards a market-friendly investment regime, my main argument is that there is set of institutional shortcomings present at the oil regulatory model in force, making the energy reform’s liberalization objective far from being complete./nBased upon a political economy approach toward institutions and a comparative analysis of the Norwegian petroleum regime, the present case study applies a concept of checks and balances –as governing standard– to evaluate the new governance model by which the Mexican state has decided to exert control over oil exploration and production activity./nThis research identifies sources of excessive administrative discretion and power concentration at the level of 1) the rules governing property rights, 2) the public law contract regime for upstream oil activities, and 3) the administrative state on petroleum in Mexico. The array of failures affecting a balanced oil regime in Mexico lead this critique to put into question whether the government has the capacity to credibly commit to a robust liberalizing policy of its upstream oil business./nMore importantly, the institutional design weaknesses stressed by this analysis suggest the persistence of a rentier-state logic shadowing Mexico’s upstream oil governance. This rentier function seems to be guaranteed by a full state ownership structure that is much more flexible and permissive than that of the past, but still grants discretionary command and control of this extractive industry to the presidential administration –which ultimately plays against the sector’s development.

Advisor: Cooter, Robert D
Post, Alison E
Learning to Learn with Gradients

Humans have a remarkable ability to learn new concepts from only a few examples and quickly adapt to unforeseen circumstances. To do so, they build upon their prior experience and prepare for the ability to adapt, allowing the combination of previous observations with small amounts of new evidence for fast learning. In most machine learning systems, however, there are distinct train and test phases: training consists of updating the model using data, and at test time, the model is deployed as a rigid decision-making engine. In this thesis, we discuss gradient-based algorithms for learning to learn, or meta-learning, which aim to endow machines with flexibility akin to that of humans. Instead of deploying a fixed, non-adaptable system, these meta-learning techniques explicitly train for the ability to quickly adapt so that, at test time, they can learn quickly when faced with new scenarios./nTo study the problem of learning to learn, we first develop a clear and formal definition of the meta-learning problem, its terminology, and desirable properties of meta-learning algorithms. Building upon these foundations, we present a class of model-agnostic meta-learning methods that embed gradient-based optimization into the learner. Unlike prior approaches to learning to learn, this class of methods focus on acquiring a transferable representation rather than a good learning rule. As a result, these methods inherit a number of desirable properties from using a fixed optimization as the learning rule, while still maintaining full expressivity, since the learned representations can control the update rule./nWe show how these methods can be extended for applications in motor control by combining elements of meta-learning with techniques for deep model-based reinforcement learning, imitation learning, and inverse reinforcement learning. By doing so, we build simulated agents that can adapt in dynamic environments, enable real robots to learn to manipulate new objects by watching a video of a human, and allow humans to convey goals to robots with only a few images. Finally, we conclude by discussing open questions and future directions in meta-learning, aiming to identify the key shortcomings and limiting assumptions of our existing approaches.

Advisor: Levine, Sergey
Abbeel, Pieter
Localized States in Dissipative Systems with Spatially Periodic Modulation

The Ginzburg-Landau equation with spatially periodic parametric forcing is used to/nstudy localized states near a weakly subcritical steady-state bifurcation. First the speed and/nstability of fronts near such a bifurcation are studied without spatial forcing, focusing on the/ntransition between pushed and pulled fronts. Exact nonlinear front solutions are constructed/nand their stability properties investigated. In some cases, the exact solutions are stable but/nare not selected from arbitrary small amplitude initial conditions. In other cases, the exact/nsolutions are unstable to modulational instabilities which select a distinct front. Chaotic/nfront dynamics may result and is studied using numerical techniques./nWhen periodic spatial forcing is added the Ginzburg-Landau equation exhibits bistabil-/nity between the trivial state and a nontrivial periodic state. It is shown that a family of/nstationary localized states accumulate near the Maxwell point of the homogeneous problem./nNumerical continuation is used to show that under appropriate conditions these localized/nstates are organized within a snakes-and-ladders structure. This phenomenon is named/nforced snaking. The stability properties of these states are determined and it is shown that/nlonger lengthscale forcing leads to stationary trains consisting of a finite number of strongly/nlocalized, weakly interacting pulses exhibiting foliated snaking./nThe phenomenon of forced snaking is not only relevant in dissipative systems and is/nintroduced in the study of gap solitons. These solitons are described by the cubic-quintic/nGross-Pitaevskii equation with a spatially periodic potential. The stability of the forced/nsnaking solutions in the gap soliton context is determined. It is shown that multi-pulse solu-/ntions of all parities are stabilized when the spatial scale of the periodic forcing is sufficiently/nlarge, effectively quenching the self interactions between the pulses. Finally it is shown that/nthe solitons unbind from the potential when subjected to sufficiently large perturbations and/na strongly nonlinear theory is derived to capture the dynamics during this transition.

Advisor: Knobloch, Edgar
Space-based constraints on NOx lifetime using high-resolution NO2 retrievals

Satellite observations of NO2 provide information about the spatial and temporal variability of NO2 column densities that can be used to infer the processes controlling NO2 concentrations. However, satellite observations require a priori information to properly transform the observed radiances into vertical column densities. Previous work has shown that using a priori data at equal or better spatial resolution to the satellite pixels significantly improves the retrieved NO2. Of particular importance are the a priori vertical profiles that represent the vertical distribution of NO2 within each satellite pixel./nIn this dissertation, I show that the temporal resolution of the a priori NO2 profiles, as well as the spatial resolution, is important to accurately retrieve NO2. I show that using profiles with high spatial resolution, but coarse temporal resolution, overestimates the rate at which NO2 is lost in the outflow from an urban source, and that high spatial and temporal resolution of these profiles is necessary to simultaneously retrieve the NO2 column density and lifetime in an urban plume. To account for this, I design and validate an upgrade to the Berkeley High Resolution (BEHR) NO2 retrieval that incorporates daily, high resolution profiles for over 7 years. With this retrieval, I show direct observations of the relationship between NOx concentration and lifetime by examining the weekend-weekday changes in column density and lifetime from several US cities between 2005 and 2014. Specifically, I show that Chicago, IL and Dallas, TX are undergoing a transition from NOx-suppressed to NOx-limited chemistry, which may indicate that future reductions in NOx emissions will be more effective at controlling O3 production, but have less direct effect on NOx concentrations.

Advisor: Cohen, Ronald C
Measurement techniques for atmospheric nitrogen oxides and observational constraints on alkyl nitrate chemistry

NOx (NO + NO2) molecules act as a control over atmospheric oxidation rates. The chemical lifetime of NOx is controlled by daytime OH-initiated photochemical reactions and nighttime NO3-initiated reactions. One class of products of this chemistry, alkyl nitrates (denoted by the general formula RONO2), is formed by both daytime and nighttime processes, but the balance between these processes is not well understood. In order to investigate mechanisms of RONO2 production and thus shed light on this balance, measurements of reactive nitrogen and other relevant species were taken during three field campaigns, two in Colorado during summer 2014, the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) and Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality (Discover-AQ), and one in the northeast US in winter 2015, Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER). Evidence is presented showing that the nighttime pathway for RONO2 formation, often considered a negligible source compared to daytime production, results in concentrations that are up to half of observed daytime concentrations. High RONO2 concentrations observed in the morning at constant ozone that cannot be explained by loss processes, mixing, or other sources point to rapid nighttime production via NO3 chemistry. This result is surprising because, while nighttime NO3 chemistry has often been shown to be a significant source of organic aerosol, especially in rural regions dominated by biogenic emissions, it has not been shown to be a significant source of alkyl nitrates in an urban area. In addition, measurement comparisons are presented in order to evaluate the accuracy of the observations used in this analysis and to evaluate the winter and nighttime performance of instruments that have been previously well characterized for summer and daytime operation. For the WINTER campaign, comparisons between measurements of the same species using different operating principles showed agreement to better than 20%. The measurements from WINTER show a comprehensive observation-based view of the partitioning of nitrogen oxides under winter and nighttime conditions not previously demonstrated. For FRAPPE and Discover-AQ, a method is presented for comparing measurements between instruments flown on two different aircraft with different flight paths. This comparison shows agreement to within expected accuracies for all 13 species compared except for the total RONO2 measurement (ΣRONO2), a measurement of the sum of all species with the RONO2 general formula. A comparison of ΣRONO2 with measurements of individual RONO2 species scaled to approximate ΣRONO2 reveals a systematic error in the Discover-AQ ΣRONO2 measurements; reasons for this error are discussed.

Advisor: Cohen, Ronald
Polarized Federalism: Activists, Voters, and the Resurgence of State Policy in the U.S.

This dissertation investigates the causes and consequences of policy variation and policy polarization in the U.S. states. Chapter 2 describes policy change over time. Since the 1970s, state governments have implemented important policies while national policymaking has slowed, such that Americans' relationships to government are increasingly determined by their states of residence. This policy variation is increasingly associated with party control of state government, and carries major consequences for the lives of residents. Chapter 3 further investigates the measurement of policy outcomes, suggesting that prior measures may understate policy polarization in recent years. Chapter 4 estimates the relationship between public opinion and policy outcomes. Results suggest that this relationship varies widely by policy issue area, with marijuana and LGBT rights policy showing strong responsiveness. While public opinion may play an inconsistent role in state policy change, Chapter 5 suggests that changes in activist group behavior may influence legislative behavior and policy outcomes in the states. The implications of this dissertation challenge traditional theories of federalism and state politics, suggesting that organized and well-resourced political actors, not ordinary voters, have collapsed American politics into a single national arena of contestation over the direction of public policy.

Advisor: Pierson, Paul
Schickler, Eric
On Betti Tables, Monomial Ideals, and Unit Groups

This thesis explores two topics in commutative algebra. The first topic/nis Betti tables, particularly of monomial ideals, and how these relate to/nBetti tables of arbitrary graded ideals. We systematically study the/nconcept of mono, the largest monomial subideal of a given ideal, and/nfor an Artinian ideal I, deduce relations in the last column of the Betti/ntables of I and mono(I). We then apply this philosophy towards a/nconjecture of Postnikov-Shapiro, concerning Betti tables of certain ideals/ngenerated by powers of linear forms: by studying monomial subideals/nof the so-called power ideal, we deduce special cases of this conjecture./nThe second topic concerns the group of units of a ring. Motivated by/nthe question of when a surjection of rings induces a surjection on unit/ngroups, we give a general sufficient condition for induced surjectivity to/nhold, and introduce a new class of rings, called semi-fields, in the process./nAs units are precisely the elements which avoid all the maximal ideals,/nwe then investigate infinite prime avoidance in general, and in this/ndirection, produce an example of a ring that is not a semi-field, for which/nsurjectivity on unit groups still holds.

Advisor: Eisenbud, David
Correlation of Nanohardness to Bulk Mechanical Tensile and Shear Properties through Direct Characterization and Comparison of Neutron-Irradiated Steels

Nanoindentation has been used for decades to assess materials on a local scale and to obtain fundamental mechanical property parameters. Nuclear materials research often faces the challenge of testing rather small samples due to the hazardous nature, limited space in reactors, and shallow ion-irradiated zones, fostering the need for small-scale mechanical testing (SSMT). As such, correlating the results from SSMT to bulk properties is particularly of interest. This thesis compares macroscopic tensile (σy, σflow, and σuts) and shear punch (τy and τmax) test results to nanoindentation hardness data (H) obtained on a number of different neutron-irradiated materials in order to understand the relationship and scaling behavior on radiation-damaged samples. Various empirical relationships are employed and compared. In addition, multiple methods for obtaining hardness numbers from the load-displacement (LD) curves generated during instrumented indentation testing (IIT) are analyzed. After investigating many permutations of LD curve analysis methods and empirical relationships, combinations for specific cases are suggested based on expected material behavior. Utilizing these suggestions, efficacious relationships are found between hardness, tensile yield, tensile flow, and shear max.

Advisor: Hosemann, Peter
Simulating Nonlinear Faraday Waves on a Cylinder

In 1831, Michael Faraday observed the formation of standing waves on the surface of a vibrating fluid body. Subsequent experiments have revealed the existence of a rich tapestry of patterned states that can be accessed by varying the frequency and amplitude of the vibration and have spurred vast research in hydrodynamics and pattern formation. These include linear analyses to determine the conditions for the onset of the patterns, weakly nonlinear studies to understand pattern selection, and dynamical systems approaches to study mode competition and chaos. Recently, there has been some work towards numerical simulations in various three-dimensional geometries. These methods however possess low orders of accuracy, making them unsuitable for nonlinear regimes./nWe present a new technique for fast and accurate simulations of nonlinear Faraday waves in a cylinder. Beginning from a viscous potential flow model, we generalize the Transformed Field Expansion to this geometry for finding the highly non-local Dirichlet-to-Neumann operator (DNO) for the Laplace equation. A spectral method relying on Zernike polynomials is developed to rapidly compute the bulk potential. We prove the effectiveness of representing functions on the unit disc in terms of these polynomials and also show that the DNO algorithm possesses spectral accuracy, unlike a method based on Bessel functions./nThe free surface evolution equations are solved in time using Picard iterations carried out by left-Radau quadrature. The results are in perfect agreement with the instability thresholds and surface patterns predicted for the linearized problem. The nonlinear simulations reproduce several qualitative features observed experimentally. In addition, by enabling one to switch between various nonlinear regimes, the technique allows a precise determination of the mechanisms triggering various experimental observations.

Advisor: Wilkening, Jon A