VictorJuiz/thesis huggingface dataset:
Multiple antenna transmitter design under power constraints [electronic resource]

Multiple-antenna technique is one of the fundamental building blocks for modern wireless communication systems. The spatial degrees of freedom provided by multiple antennas when used with appropriate transmit coding and receive signal processing, offer several performance advantages including array gain, diversity gain and multiplexing gain. Most theoretical results in multiple-antenna theory assume a sum-power constraint for the transmit antennas. However, practical multiple-antenna transmitters are often subject to per-Power Amplifier (PA) constraint and sometimes also Effective Isotropic Radiated Power (EIRP) constraint. These constraints are motivated by bio-safety, interference reduction and lower cost. However, per-PA power constrained systems suffer from performance loss under imbalances in channel gains at the transmit antennas that often occur in the presence of fading. This thesis studies point-to-point and multi-point-to-point transmission under per-PA power and EIRP constraints, focusing on techniques to increase link performance and to reduce algorithmic complexity. The first part of this thesis studies the use of a Power Combining Network (PCN) to improve link performance under a per-PA power constraint. A PCN switches the outputs of PAs associated with antennas with poor channels to antennas with good channels. The PCN balances the higher coupling gain of the PA power with the loss of array gain or diversity gain. We also study PCN design when an additional EIRP constraint is imposed. We develop fast algorithms for determining the optimal PCN under both a per-PA power constraint alone or with an additional EIRP constraint. We demonstrate the effectiveness of PCN through performance analysis and numerical evaluation. The second part of this thesis is motivated by reducing computational complexity of transmit beamforming algorithms in multi-point-to-point, so called a Coordinated Multi-Point (CoMP), transmission. Algorithmic complexity is high in CoMP since calculating the joint optimal transmit beamformers typically involves an iterative computation of intermediate solutions across the multiple base stations. We present a low-complexity minimum-mean-squared-error beamforming algorithm for CoMP transmission under per-PA power constraint. We decompose the original beamforming problem at each base station into a series of simpler sub-problems. Solution of each sub-problem is derived in a closed-form, and convergence proof and complexity analysis are presented. We demonstrate significant saving in computational complexity without compromising performance which is confirmed by numerical evaluation.

Keywords: Electrical Engineering.
Advisor: Katti Sachin primary advisor. Thesis advisor
Paulraj Arogyaswami primary advisor. Thesis advisor
Cioffi John M. advisor. Thesis advisor
Multivariate density estimation by Bayesian sequential partitioning and its applications [electronic resource]

Consider a class of densities which are piecewise constant functions over partitions of the sample space defined by sequential coordinate partitioning. We introduce a prior distribution for a density in this function class and derive in closed form the marginal posterior distribution of the corresponding partition. A computationally efficient method, based on sequential importance sampling, is presented for the inference of the partition from this posterior distribution. Compared to traditional approaches such as the kernel method or the histogram, the Bayesian sequential partitioning (BSP) method proposed here is capable of providing much more accurate estimates when the sample space is of moderate to high dimension. We illustrate this by simulated as well as real data examples. The examples also demonstrate how BSP can be used to design new classification methods and data compression methods competitive with or even superior to the state of the art. For the data compression application, we use sequence data of format FASTQ from human chromosome 21 and validate the performance of our method on both lossless and lossy compression.

Keywords: Statistics.
Advisor: Wong Wing Hung primary advisor. Thesis advisor
Hastie Trevor advisor. Thesis advisor
Walther Guenther advisor. Thesis advisor
The musical reception of Torquato Tasso's Rime, 1571-1620 [electronic resource]

Arguably the most prominent poet of late 16th-century Italy, Torquato Tasso (1544-1595) produced throughout his career more than 1,500 lyric poems, collectively known as Rime. About 180 of these poems, for the most part madrigali liberi, enjoyed a remarkable musical fortune in the late 16th and early 17th centuries. Indeed, between 1571 and 1620 they received about 500 polyphonic settings by composers of varied geographical provenance, ranging from central Europe to Sicily. In this dissertation I explore this vast poetic-musical repertoire, to which both literary scholars and musicologists have so far devoted limited attention. In so doing, I pursue two main research avenues: the first is to understand how these poems became musical hits; the second is to determine how composers set them to music, providing a snapshot of compositional personalities and schools. The dissertation is divided in two parts. Part I is titled "Selected Centers" and is composed of four chapters, each on a center where Tasso's lyric poems received a particularly large number of settings. The centers I examine are Ferrara, Mantua, Genoa, and Prague. In these chapters, I study how local literary trends and contacts with Tasso and his entourage influenced the production of Rime settings in each center. In addition, I analyze the musical settings, determining how they fit within local compositional styles. Part II is titled "Selected Poems" and is composed of three chapters that explore the musical reception of two specific poems, "Non è questa la mano" and "La bella pargoletta, " and of group of poems, the canzonettas. In these chapters I focus on the question of transmission, tracing where composers drew the texts from, and on stylistic analysis. The dissertation is accompanied by an appendix with an up-to-date list of the extant settings of Tasso's lyric poems.

Keywords: Music.
Advisor: Berger Karol
Newcomb Anthony
Gerbino Giuseppe
Grey Thomas S.
Rodin Jesse advisor. Thesis advisor
My Little (Homo)Nationalist Pony: a Critique of Zoophilia

This essay won the 2013 Stanford University's Michelle Zimbalist Rosaldo Prize for undergraduate work. It provides a theoretical framework on zoophilia and post-humanist thinking in relationship to racism and neo-colonialism.

Keywords: queer theory
queer studies
zoophilia
neocolonialism
queer activism
ecofeminism
sexual identity
sexual violence
dehumanization of racialized sexualities
human-animal relationships
bestiality
non-human animal erotica
Stanford University Feminist Gender and Sexuality Studies
Thesis
The myth of school improvement [electronic resource] : more than a decade of reform in one school and what it suggests about the American school improvement project

For more than a decade, state and federal accountability policies have operated on the assumption that the school organization may improve continuously over a period of time, whether by adopting the behaviors of effective schools or by implementing Comprehensive School Reform. This dissertation takes a critical look at the problem of school improvement by documenting what happened at a California K-8 school from its origins in 1992 through 2008. The featured case was established as a developmental, multiage program and for ten years participated as a leadership site in the Bay Area School Reform Collaborative (BASRC). Drawing on institutional and organizational theory, this study uses a longitudinal, process-sequencing approach to document what happened inside the school. Multiple instances of principal turnover, episodes of major teacher turnover and policy changes affected the school's identity, organizational boundaries, curriculum and instruction and routines and relationships. Over time the school was isomorphic with its environment, changing in response to changes in district, state and federal regulatory policies, with certain events having path-dependent consequences for the school's trajectory. Under state and federal accountability policies individual schools are held responsible for improvement; this case illustrates how these same policies shifted significant decisions and authority over curriculum and instruction to the district and state levels. School principals were instrumental in establishing a tone of trust by making and breaking decision-making agreements and structures, but these structures were increasingly symbolic in nature. This case thus suggests limits to ideals such as school leadership, data-driven decision-making and continuous improvement, and raises questions about the notion of school capacity. Given continuous churn in policies and people comprising a school, the concept of school improvement deserves revaluation. Additionally, the study contributes to theory about schools as loosely-coupled systems, suggesting that tighter administrative control over schools does not necessarily make the system more tightly coupled. Finally, I argue that school improvement has become institutionalized across the field, but churn in the policies and people that comprise a school may make the school organization a meaningless unit of change.

Keywords: Education.
Advisor: McLaughlin Milbrey Wallin primary advisor. Thesis advisor
Bridges Edwin M.
Callan Eamonn advisor. Thesis advisor
Labaree David F.
Nanometer tip-based ultrafast electron sources [electronic resource] : emission processes and direct pulse characterization techniques

Since the first half of the 20th century, metal tips ending in hemispheres with a radius of curvature of hundreds of nanometers or less have been used as stochastic field emission electron sources because the small radius of curvature allows the application of very strong electric fields to the tip apex. These tips are high brightness electron sources because they have very small virtual source sizes-typically smaller than the tip radius. In this work, field emission tips are operated as pulsed electron sources triggered by a femtosecond laser; thus, the temporal profile of the electron emission is determined by the laser pulse, but the source size is much smaller than the diffraction-limited laser focal spot. Furthermore, due to optical field enhancement at the tip apex, it is possible to get into the strong field regime, where electron emission happens on a time-scale shorter than the optical period. Possible applications of these sources include ultrafast x-ray tubes, improved ultrafast time-resolved electron microscopy and diffraction, injectors for laser accelerators, and quantum optics experiments with time-tagged electrons. The first part of this thesis presents a unified picture of the ultrafast laser-induced emission processes (photo-assisted field emission, multiphoton emission and strong field photoemission, thermally enhanced field emission) and experimental characterization of these processes. The second half describes two ongoing experiments that seek to directly characterize the electron pulses in time. The first is based on streaking the bias field of the tip, which maps the electron emission time onto electron kinetic energy. The second is a cross-correlator for electrons and photons, where an electron absorbs a photon in the near field created by scattering light from a nanostructure. These experiments will constitute not only the first direct measurement of the electron pulse duration in this system but will also point the way towards new techniques for manipulating ultrafast electron pulses with optical and microwave fields.

Keywords: Physics.
Advisor: Kasevich Mark A. primary advisor. Thesis advisor
Bucksbaum Philip H. advisor. Thesis advisor
Byer R. L. (Robert L.)
Nanophotonic computational design [electronic resource]

In contrast to designing nanophotonic devices by tuning a handful of device parameters, we have developed a computational method which utilizes the full parameter space to design linear nanophotonic devices. We show that our method may indeed be capable of designing any linear nanophotonic device by demonstrating designed structures which are fully three-dimensional and multi-modal, exhibit novel functionality, have very compact footprints, exhibit high efficiency, and are manufacturable. In addition, we also demonstrate the ability to produce structures which are strongly robust to wavelength and temperature shift, as well as fabrication error. Critically, we show that our method does not require the user to be a nanophotonic expert or to perform any manual tuning. Instead, we are able to design devices solely based on the user's desired performance specification for the device.

Keywords: Electrical Engineering.
Advisor: Vuckovic Jelena primary advisor. Thesis advisor
Fan Shanhui
Miller D. A. B. advisor. Thesis advisor
Nanophotonics [electronic resource] : near-field light propagation and optical force

Nanophotonics is the study of light at a nanometer to micrometer scale. In this thesis, I present my work on two sub-fields of nanophotonics: near-field light propagation and optical force. In the near-field limit, where the light's propagation distance is shorter than the wavelength of light, light propagation is not restricted by the macroscopic diffraction limit. As a result, field patterns with sub-wavelength feature size are allowed. I will show that it is possible to intuitively describe this system in wavevector space. I will also show that it is possible to enhance the field in this system by the use of an interface between a positive- and a negative-permittivity material. This field enhancement can be used to compensate the decay that is characteristic of near-field propagation in free-space. It also allows the system to be optimized for image-transfer purposes, where the goal is to have the image resembles the original input field. In optical force studies, the presence of light in optical systems can exert an electromagnetic force on an object. For example, two parallel waveguides with light propagating along them can experience a force that pushes or pulls the two waveguides. The force in this system allows us to design a non-volatile optical memory, which, unlike conventional optical memory, can maintain a state without the need of continuous input power. I will also study the force between a waveguide and a coupled resonator. I will show that there is a fundamental limit on the system, and show a more complicated setup where the limit is overcome. Finally, I study the existence of an optical equilibrium in the optical force in the waveguide-resonator system. I will show that optical equilibrium cannot be obtained in a single-resonance system and requires the interaction between two resonances.

Keywords: Applied Physics.
Advisor: Digonnet Michel J. F. primary advisor. Thesis advisor
Fan Shanhui
Miller D. A. B. advisor. Thesis advisor
Nanoscale transverse Fabry-Perot resonators [electronic resource]

The ability to fabricate multiple resonant photodetectors, each with separately engineered wavelength sensitivity, in a single-step process has many potential applications. In this dissertation, we propose and demonstrate the use of nanoscale semiconductor fin structures surrounded by metal as efficient transverse Fabry-Perot resonators which allow one to efficiently excite in-plane resonances under surface-normal incidence. We show that these devices support strong absorption resonances that can be tuned by varying the width of the structure and use this effect to engineer devices for two potential application areas. In the first part of the dissertation, we show how we can engineer nanoscale planar multispectral image sensors based on silicon fins surrounded by metallic slits wherein the resonant wavelength of each pixel is determined by the width of the silicon fin. The same metallic structure is used for both light confinement and carrier extraction in a compact metal-semiconductor-metal (MSM) geometry. We experimentally study how close we can put two of these pixels together and how small we can make an individual pixel. We show that, in principle if the electrical properties of the devices are suitably controlled, one can engineer devices with pixel pitch down to 250 nm and pixel sizes down to 500 nm by 500 nm. In the second part of the dissertation, we use this effect to enhance the indirect absorption in germanium and engineer CMOS-compatible germanium photodetectors with high responsivity across the telecommunications bands (both C and L bands). Finally, we show that this effect can be used to engineer passive devices like novel resonant waveguide couplers that can be used to couple light efficiently from free space to both dielectric and plasmonic slot waveguides with slot widths ~ 50 nm.

Keywords: Electrical Engineering.
Advisor: Miller D. A. B. primary advisor. Thesis advisor
Brongersma Mark L. advisor. Thesis advisor
Fan Shanhui
Nanosecond pulsed plasma-assisted combustion [electronic resource]

In this study, the use of non-equilibrium plasmas is examined as possible methods of active control of combustion. The plasmas investigated here include nanosecond-pulsed repetitive discharges as well as nanosecond-pulsed laser-produced breakdowns. These sources are used to stabilize both premixed and jet-diffusion flames of various fuel types. The use of nanosecond-pulsed repetitive discharges to stabilize lean premixed fuel-air mixtures is found to extend the equivalence ratio for complete combustion to lower values, in some cases, below the so-called lean flammability limits. This extension depends strongly on the pulse repetition frequency or average discharge power. Simulations reveal that a significant production of radicals associated with gas heating is responsible for flame stabilization and this is attributed mainly to a dissociative quenching of electronically excited species by molecular oxygen. In jet diffusion flames, anchoring of the flame-base is best when the discharge plasma is positioned where the local equivalence ratio is between 0.8 and 1.9. Lastly, the discharge plasma source is replaced by laser-induced breakdowns. Two successive laser pulses with a variable time delay are employed to mimic repetitive breakdowns expected from a future high frequency laser source of sufficient power. From studies first carried out in pure air, it is found that the first laser breakdown causes a temporal region virtually transparent to the subsequent laser pulse during the interval from 100 ns to 60 µs. This is attributed to heating by the plasma, reducing the density below threshold levels needed for absorption of a laser pulse. In premixed fuel-air mixtures, the first breakdown induces a second region of transparency during the interval from 100 µs to 2 ms after the pulse due to the heat released by combustion. These findings limit the laser repetition rate to a maximum of 500 Hz when the equivalence ratio is 1. Time-resolved imaging of CH* chemiluminescence reveals flame front merging confirming that flame stabilization can be achieved at these moderate laser repetition rates.

Keywords: Mechanical Engineering.
Advisor: Cappelli Mark A. (Mark Antony) primary advisor. Thesis advisor
Ito Tsuyohito advisor. Thesis advisor
Mungal Mark Godfrey advisor. Thesis advisor
Nanostructures in III-V solar cells [electronic resource]

From the physics and materials viewpoint, III-V materials are ideal for highly efficient photovoltaic conversion. Their major limitations are cost and resource availability. As industrial planar III-V solar cells continue to set the all-time efficiency records, nanostructured III-V solar cells are now being investigated in academia with the goal to further improve the efficiency and lower the required materials volume and cost. However, most previously investigated nano-structured solar cells suffer from low efficiencies. In this dissertation, I first present optical enhancement in nanopyramid III-V ultra-thin films which can potentially reduce the required materials by one order of magnitude. I then demonstrate significant efficiency improvement in GaAs solar cell. Especially, with an AlGaAs nanocone window layer, a 17%-efficiency nanostructured single-junction solar cell is obtained. The first part of my dissertation focuses on optical engineering and absorption improvement in nanopyramid GaAs ultra-thin film. I demonstrate a double-sided nanopyramid GaAs film that is only 160 nm thick, laminated in a flexible transparent superstrate. Without additional antireflection coatings, this nanopyramid film absorbs over 80% more photons than a planar counterpart with equal thickness at normal incidence and is equivalent to a 1um thick film. At large incident angles, this enhancement can be even greater. With similar light trapping design, III-V solar cell film thickness can be potentially reduced from 3-4 um to 200-300 nm, which could significantly reduce III-V cell cost. The second part of my dissertation focuses on efficiency improvement in III-V nanostructured solar cells. First, GaAs solar cell efficiency enhancement using ZnO nanoparticle antireflection coating is briefly demonstrated. I then demonstrate our work on nanostructured p-n junction solar cells and discuss the challenges for nanostructured solar cell. After this, I propose a nanowindow solar cell design that can overcome these challenges by enhancing both optical and electrical properties. A nanowindow solar cell using a nanocone AlGaAs window layer, a GaAs junction and mesa grid contact is demonstrated with a high energy conversion efficiency of 17.0% and high open circuit voltage of 0.982 V.

Keywords: Physics.
Advisor: Harris J. S. (James Stewart)
Cui Yi
Fan Shanhui
Hollberg Leo (Leo William)
Narrative ambition [electronic resource] : Victorian self-help and competition

This dissertation investigates the Victorian narrative of ambition across its two key genres, the novel and the self-help text. The term and the genre of "self-help" were invented in the nineteenth century, with Thomas Carlyle coining the term in Sartor Resartus (1834), and Samuel Smiles preaching its importance in his 1859 Self-Help, which collected and condensed the biographies of great men in order to illustrate the importance of hard work, perseverance, and energy. Whereas Smiles's brief, condensed biographies focus on the individual, in the novel, the self-help plot expands to explore the dangers of excessive ambition in a competitive and hierarchical society. I suggest that the Victorian narrative of ambition divided into two paths, and whereas Smiles's self-help ethos focuses on the individual's ambition--with each person rising "very much according to his deserts"--the novel takes on the wider social context of ambition, as many ambitious self-helping characters compete, crowding a fictional world that, as one of Anthony Trollope's characters laments, "will soon be like a fishpond, very full of fish, but with very little food for them." Across chapters focusing on Smiles's Self-Help, Dinah Mulock Craik's John Halifax, Gentleman, Charles Dickens's Our Mutual Friend, William Makepeace Thackeray's The Luck of Barry Lyndon and Vanity Fair, and Anthony Trollope's The Three Clerks and An Autobiography, I argue that these Victorian authors used varying narrative strategies to dramatize ambition. Smiles's Self-Help repeats the same story of successful ambition across hundreds of examples, seeming to replicate in its form the perseverance of the characters. But whereas Smiles uses these stories to praise ambitious work, the Victorian novel explores the consequences of ambition--both within the story, as the ambitious subject seeks to displace others in the process of "getting ahead, " and in the telling, as narrators exaggerate, satirize, and judge the ambitions of the novel's characters. Ultimately, this dissertation argues that dramatizing ambition has both formal and stylistic consequences on the Victorian novel.

Keywords: English.
Advisor: Moretti Franco
Woloch Alex
Gigante Denise