This thesis contains five short stories, each narrated by a character with a psychological disorder. The disorders represented are as follows: alcohol use disorder, schizophrenia, Alzheimer’s disease, phobic disorder, and autism spectrum disorder. Research was conducted in two parts: (1) study of psychological texts including peer reviewed articles and case studies and (2) study of literary works including memoirs and novels. The author aims to use storytelling to humanize and therefore generate empathy for those with mental illnesses.

Non-volatile memories (NVM) including flash memories and resistive memories have attracted significant interest as data storage media. Flash memories are widely employed in mobile devices and solid-state drives (SSD). Resistive memories are promising as storage class memory and embedded memory applications. Data reliability is the fundamental requirement of NVM as data storage media. However, modern nano-scale NVM suffers from challenges of inter-cell interference (ICI), charge leakage, and write endurance, which threaten the reliability of stored data. In order to cope with these adverse effects, advanced coding techniques including soft decision decoding have been investigated actively. However, current coding techniques do not capture the physical properties of NVM well, so the improvement of data reliability is limited. Although soft decision decoding improves the data reliability by using soft decision values, it degrades read speed performance due to multiple read operations needed to obtain soft decision values. In this dissertation, we explore coding schemes that use side information corresponding to the physical phenomena to improve the data reliability significantly. The side information is obtained before writing data into memory and incorporated during the encoding stage. Hence, the proposed coding schemes maintain the read speed whereas the write speed performance would be degraded. It is a big advantage from the perspective of speed performance since the read speed is more critical than the write speed in many memory applications. First, this dissertation investigates the coding techniques for memory with stuckat defects. The idea of coding techniques for memory with stuck-at defects is employed to handle critical problems of flash memories and resistive memories. For 2D planar flash memories, we propose a coding scheme that combats the ICI, which is a primary challenge of 2D planar flash memories. Also, we propose a coding scheme that reduces the effect of fast detrapping, a degradation factor in 3D vertical flash memories. Finally, we investigate the coding techniques that improve write endurance and power consumption of resistive memories.

Le contexte de ces travaux de thèse est la nécessité de développer des procédés innovants pour produire des matériaux nouveaux ou aux propriétés améliorées. Une des solutions envisagées est l'élaboration de matériaux denses nanostructurés. L'objectif a été de concevoir et développer un dispositif de mise en forme de matériaux pulvérulents par frittage FLASH, couplé à la possibilité de réaliser une compaction dynamique, en vue d'obtenir des matériaux aux microstructures originales. Dans un premier temps, le développement et la conception du dispositif ont été réalisés. La suite de l'étude a eu pour objectif l'analyse et la compréhension du fonctionnement du dispositif à travers une analyse mécanique et une étude des matériaux. L'étude mécanique a permis de déterminer la manière dont se propagent les ondes dans ce nouveau dispositif. L'objectif a été la mise en place d'une méthode de correction de propagation des ondes dans le dispositif DCRS, qui pourrait permettre d'estimer l'énergie stockée dans le matériau due à la déformation à partir de l'obtention des courbes contrainte-déformation. L'insertion des éléments en graphite permettant de réaliser le frittage des matériaux pulvérulents provoque en effet une discontinuité mécanique avec les barres métalliques, perturbant la propagation des ondes élastiques. L'étude de l'effet du graphite est déterminée par une étude numérique, et confirmée par les résultats expérimentaux. Une méthode corrective a été mise en place afin de corriger l'effet du graphite sur la propagation des ondes élastiques. L'étude matériaux a permis d'étudier les effets de la compaction dynamique sur les propriétés physiques de différents matériaux mise en forme avec le dispositif DCRS. Une première étape a été la détermination des mécanismes de durcissement d'un cuivre Oxide dispersion Strengthened (ODS) mise en forme avec le dispositif DCRS. L'objectif était d'estimer l'énergie stockée dans le matériau lors de la compaction dynamique pour une température de frittage donnée. Après la caractérisation du cuivre ODS réalisée et les paramètres de mise en forme du cuivre ODS définis, l'analyse des mécanismes de durcissement a permis d'identifier les perspectives pour l'optimisation de la mise en forme de tels matériaux. Une seconde étape a abordé les relations entre microstructures et propriétés physiques dans un nickel pur via les variations de vitesses d'impact et de température auxquelles est effectuée la compaction dynamique lors d'un cycle thermique défini. Les phénomènes physiques de réorganisation microstructurale intervenant lors de la compaction dynamique comme la recristallisation dynamique et le stockage de l'énergie ont ainsi été mis en évidence / This works investigates a new process development in order to consolidate materials with original microstructures thus improved properties. The technological approach was to use powder metallurgy processes and combine FAST sintering with dynamic compaction. In parallel to elastic wave propagation study into the system, a systematic parametric study on the influence of the processing parameters on the material properties was made

Im Rahmen dieser Arbeit wurden elektronische Bauelemente wie Feldeffekttransistoren, elektronische Speicherelemente sowie resonante Tunneldioden hinsichtlich neuartiger Transporteigenschaften untersucht, die ihren Ursprung in der Miniaturisierung mit Ausdehnungen kleiner als charakteristische Streulängen haben. Die Motivation der vorliegenden Arbeit lag darin, die Physik nanoelektronischer Bauelemente durch einen neuen Computercode: NANOTCAD nicht nur qualitativ sondern auch quantitativ beschreiben zu können. Der besondere Schwerpunkt der Transportuntersuchungen lag im nicht-linearen Transportbereich für Vorwärtsspannungen, bei denen die Differenz der elektrochemischen Potentiale im aktiven Bereich der Bauelemente bei Weitem größer als die thermische Energie der Ladungsträger ist, da nur im nicht-linearen Transportbereich die für eine Anwendung elektronischer Bauelemente notwendige Gleichrichtung und Verstärkung auftreten kann. Hierzu war es notwendig, eine detaillierte Charakterisierung der Bauelemente durchzuführen, damit möglichst viele Parameter zur genauen Modellierung zur Verfügung standen. Als Ausgangsmaterial wurden modulationsdotierte GaAs/AlGaAs Heterostrukturen gewählt, da sie in hervorragender struktureller Güte mit Hilfe der Molekularstrahllithographie am Lehrstuhl für Technische Physik mit angegliedertem Mikrostrukturlabor hergestellt werden können. Im Rahmen dieser Arbeit wurde zunächst ein Verfahren zur Bestimmung der Oberflächenenergie entwickelt und durchgeführt, das darauf beruht, die Elektronendichte eines nahe der Oberfläche befindlichen Elektronengases in Abhängigkeit unterschiedlicher Oberflächenschichtdicken zu bestimmen. Es zeigte sich, dass die so bestimmte Oberflächenenergie, einen äußerst empfindlichen Parameter zur Beschreibung miniaturisierter Bauelemente darstellt. Um die miniaturisierte Bauelemente zu realisieren, kamen Herstellungsverfahren der Nanostrukturtechnik wie Elektronenstrahllithographie und diverse Ätztechniken zum Einsatz. Durch Elektronmikroskopie wurde die Geometrie der nanostrukturierten Bauelemente genau charakterisiert. Transportmessungen wurden durchgeführt, um die Eingangs- und Ausgangskennlinien zu bestimmen, wobei die Temperatur zwischen 1K und Raumtemperatur variiert wurde. Die temperaturabhängigen Analysen erlaubten es, die Rolle inelastischer Streuereignisse im Bereich des quasi-ballistischen Transports zu analysieren. Die Ergebnisse dieser Arbeit wurden dazu verwendet, um die NANOTCAD Simulationswerkzeuge soweit zu optimieren, dass quantitative Beschreibungen von stark miniaturisierten, elektronischen Bauelementen durch einen iterativen Lösungsalgorithmus der Schrödingergleichung und der Poissongleichung in drei Raumdimensionen möglich sind. Zu Beginn der Arbeit wurden auf der Basis von modulationsdotierten GaAs/AlGaAs Heterostrukturen eine Vielzahl von Quantenpunktkontakten, die durch Verarmung eines zweidimensionalen Elektronengases durch spitz zulaufende Elektrodenstrukturen realisiert wurden, untersucht. Variationen der Splitgate-Geometrien wurden statistisch erfasst und mit NanoTCADSimulationen verglichen. Es konnte ein hervorragende Übereinstimmung in der Schwellwertcharakteristik von Quantenpunktkontakten und Quantenpunkten gefunden werden, die auf der genauen Beschreibung der Oberflächenzustände und der Erfassung der realen Geometrie beruhen. Ausgehend von diesen Grundcharakterisierungen nanoelektronischer Bauelemente wurden 3 Klassen von Bauelementen auf der Basis des GaAs/AlGaAs Halbleitersystems detailliert analysiert. / In this thesis electronic devices such as field effect transistors, electronic memory devices and resonant tunnelling have been examined with regard to new transport characteristics that have their origin in the miniaturization with extensions smaller than characteristic lengths. The motivation for this thesis was to be able to describe the physics of nanoelectronic devices via a new computer code: NANOTCAD not only by quality but also by quantity. The special emphasis of the transport examinations was on the non-linear transport regime for bias voltages with which the difference of the electro-chemical potentials in the active section of the devices is by far bigger than the thermic energy of the charges, for only in the non-linear transport regime we find the rectification and intensification necessary for the application of electronic devices. To achieve this it was necessary to characterize the devices in detail to have as many parameters for exact modelling as possible. Modulation-doped GaAs/AlGaAs heterostructures were chosen as basic material, for they can be produced in excellent structural quality with the help of molecular beam lithography at the Technical Physics department with attached microstructure laboratory. In this thesis first a method to determine the surface potential was developed and put into operation, a method that is based on the determination of the electron density of an electron gas near the surface in dependence of differently thick surface layers.We can see that the surface energy determined that way is an extremely sensible parameter for the description of miniaturized devices. To realize the miniaturized devices processing techniques of the nanostructure technology such as electron beam lithography and different etching techniques were used.With the electron microscopy the geometry of the nano-structured devices was exactly characterized. Transport measurements had been made to determine the input- and output characteristics with a temperature varying between 1 Kelvin and room temperature. The temperature-dependent analysis allow to analyze the role of inelastic scattering events in the sector of quasi-ballistic transport. The results of this thesis had been used to optimize the NANOTCAD simulation tools in a way that quantitative descriptions of strongly miniaturized electronic devices via an iterative solution algorithm of the Schroedinger equation and the Poisson equation in three dimensions are possible. The thesis starts with an examination of many quantum dot contacts which had been realized by a depletion of an two-dimensional electron gas via tapered electrode structures. Variations of the split gate geometries had been registered statistically and then been compared to NANOTCAD simulations. An excellent accordance in the threshold characteristics of quantum dot contacts and quantum dots could be found which are based on the exact description of surface states and the registration of the real geometry that had been determined with the analysis of electron-microscopic recordings of the structures. From these basic characteristics of nanoelectronic devices three classes of devices on the basis of the GaAs/AlGaAs semiconductor systems had been analyzed in detail.

[NO ABSTRACT PRESENT]

Spatial database systems widely employ spatial indexing structures to speed up the processing of spatial queries. Many of the proposed spatial indices in the literature, such as the R-tree, assume magnetic disks (i.e., HDDs) as the underlying storage device. They are termed as disk-based spatial indices. On the other hand, several spatial database applications are increasingly using flash-based Solid State Drives (SSDs) and thus, designing spatial indices for these storage devices has gained increasing attention. This is due the fact that, compared to HDDs, SSDs offer smaller size, lighter weight, lower power consumption, better shock resistance, and faster reads and writes. Hence, specific indices for SSDs, termed flash-aware spatial indices, have been proposed in the literature to deal with the intrinsic characteristics of SSDs, such as the asymmetric costs of reads and writes. However, the research to date has not been able to establish a flash-aware spatial index that actually exploits all the benefits of SSDs. This PhD thesis advances on the literature as follows. We firstly define a methodology to create spatial datasets for experimental evaluations. We also propose FESTIval, a versatile framework that provides a common and unique environment to execute experimental evaluations. Such contributions served as a foundation to conduct performance analysis along this PhD work. By using this foundation, we analyze the performance behavior of spatial indices on different storage devices, such as HDDs and SSDs. Further, we discuss the applicability of employing flash simulators on the evaluation of spatial indices. The findings of these experiments contributed to the proposal of eFIND, a generic and efficient framework for flash-aware spatial indexing. eFIND is generic because it can port a wide range of disk-based spatial indices to SSDs. eFIND is also efficient because it is based on a set of design goals that exploits SSD performance. Performance tests showed that, compared to the state of the art, eFIND improved the construction of ported disk-based spatial indices and the execution of spatial queries. For porting the R-tree (i.e., the eFIND R-tree), eFIND showed performance reductions from 43% to 77% to build spatial indices, and from 4% to 23% to execute spatial queries. For porting the xBR+-tree (i.e., the eFIND xBR+-tree), eFIND showed reductions from 28% to 83% to build spatial indices and up to 35% in the spatial query processing. / Sistemas de banco de dados espaciais empregam estruturas de indexação espaciais para acelerar o processamento de consultas espaciais. Muitos dos índices espaciais propostos na literatura, como a R-tree, assumem que os dispositivos de armazenamentos são os discos magnéticos (i.e., HDDs) e são denominados índices espaciais baseados em disco. Por outro lado, várias aplicações de banco de dados espaciais estão cada vez mais usando Solid State Drives (SSDs) baseados em memória flash e, assim, projetar índices espaciais para esses dispositivos tem ganhado cada vez mais atenção. Isso se deve ao fato de que, em comparação com os HDDs, os SSDs oferecem menor tamanho, menor peso, menor consumo de energia, melhor resistência a choques além de leituras e escritas mais rápidas. Assim, índices espaciais para memória flash têm sido propostos na literatura para lidar com as características intrínsecas dos SSDs, como os custos assimétricos de leituras e escritas. No entanto, a pesquisa até o momento não conseguiu estabelecer um índice espacial que realmente explora todos os benefícios dos SSDs. Esta tese de doutorado avança na literatura da seguinte forma. Primeiramente, é definida uma metodologia para criar conjuntos de dados espaciais para avaliações experimentais. Também é proposto FESTIval, um arcabouço versátil que fornece um ambiente comum e único para executar avaliações experimentais. Tais contribuições serviram como base para conduzir análises de desempenho ao longo deste trabalho de doutorado. Usando essa base, o comportamento de desempenho de índices espaciais em diferentes dispositivos de armazenamento, como HDDs e SSDs, é analisado. Além disso, discutese a aplicabilidade de simuladores flash na avaliação experimental de índices espaciais. Os resultados desses experimentos contribuíram para a proposta de eFIND, uma estrutura genérica e eficiente para indexação espacial em memórias flash. eFIND é genérico porque pode portar uma ampla gama de índices espaciais baseados em disco para SSDs. eFIND também é eficiente porque é baseado em um conjunto de objetivos de projeto que exploram o desempenho do SSD. Os testes de desempenho mostraram que, em comparação com o estado da arte, eFIND melhorou a construção de índices espaciais portados e a execução de consultas espaciais. Para portar a R-tree (ou seja, a eFIND R-tree), eFIND mostrou melhorias de desempenho de 43% a 77% para construir índices espaciais e de 4% a 23% para executar consultas espaciais. Para portar a xBR+-tree (ou seja, a eFIND xBR+-tree), eFIND mostrou melhorias de 28% a 83% para construir índices espaciais e de até 35% no processamento de consultas espaciais.

With the advance of technology and rapid growth of digital systems, low power high speed analog-to-digital converters with great accuracy are in demand. To achieve high effective number of bits Analog-to-Digital Converter(ADC) calibration as a time consuming process is a potential bottleneck for designs. This dissertation presentsa fully digital background calibration algorithm for a 7-bit redundant flash ADC using split structure and look-up table based correction. Redundant comparators are used in the flash ADC design of this work in order to tolerate large offset voltages while minimizing signal input capacitance. The split ADC structure helps by eliminating the unknown input signal from the calibration path. The flash ADC has been designed in 180nm IBM CMOS technology and fabricated through MOSIS. This work was supported by Analog Devices, Wilmington,MA. While much research on ADC design has concentrated on increasing resolution and sample rate, there are many applications (e.g. biomedical devices and sensor networks) that do not require high performance but do require low power energy efficient ADCs. This dissertation also explores on design of a low quiescent current 100kSps Successive Approximation (SAR) ADC that has been used as an error detection ADC for an automotive application in 350nm CD (CMOS-DMOS) technology. This work was supported by ON Semiconductor Corp, East Greenwich,RI.

This thesis focuses on the performace of pipeline converters and their integration on mixed signal processes. With this in mind, a 12-b 50MHz pipeline ADC has been realized in a 0.6um digital CMOS process. The architecture is based on a 1.5-b per stage structure utilizing digital correction for the first six stages. A differeintial switched capacitor circuit consisting of a cascode gm-c op-amp with 250MHz of bandwidth is used for sampling and amplification in each stage. Comparators with an internal offset voltage are used to implement the decision levels required for the 1.5-b per stage structure. Correction of the pipeline is accomplished by measuring the offset and gain of each of the first six stages using subsequent stages. The measured values are used to calculate digtal values the compensate for the inaccuracies of the analog pipeline. Corrected digital values for each stage are stored in the pipeline and used to create corrected output codes. Errors caused by measuring the first six stages using uncalibrated stages are minimized by using extra switching circuitry during calibration.

This project is a collection of interconnected short stories all based in the Los Angeles area. Each story is able to stand on its own as a short piece, but ultimately plays a larger role of possessing a relationship with those that come before and after it. The collection is broken into three segments, each segment possessing its own theme. And while each segment, and the stories within each segment, flourishes with the theme they are placed in, each and every story still interconnects with each other in order to produce the framework of the book entirely; that being the story of two young lovers: “Leslie,” and “Thomás.” These two characters that I have produced are at the basis of this project. Their stories are peppered throughout the collection in order to better convey the sporadic nature of their relationship.

acase@tulane.edu