Thesis (M. S.)--Florida State University, 2005. / Advisor: Dr. An-I Andy Wang, Florida State University, College of Arts and Sciences, Dept. of Computer Science Title and description from dissertation home page (viewed Sept. 15, 2005). Document formatted into pages; contains xi, 71 pages. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--Lehigh University, 1999. / Includes vita. Includes bibliographical references (leaves 147-151).

Thesis (MEng)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The SUNSAT RAMDISK was studied, and tests performed to assess its flight readiness. Errors were detected, and modifications had to be made to ensure proper operation. SUNSAT was subsequently launched, and to date the RAMDISK is still functioning correctly. The flight readiness testing of the RAMDISK was considered a pre-study to designing a second generation RAMDISK. A conceptual mass memory storage device support structure was designed. This second generation RAMDISK, or memory drive is intended to be used on a second generation SUNSAT, or SUNSAT 2. The design is targeted for implementation in fields programmable gate arrays (FPGA's) and was realised using VHDL. This hardware description language is an accepted standard, and can be implemented in a number of different programmable logic devices; both SRAM and fuse-link based. Simulations were performed to verity the functionality of the design, and to determine whether the data transfer specifications could be met using programmable logic devices. A modular design methodology was followed. The memory drive was designed so that any type and amount of memory can be added to the drive without a major design change. The simulations indicated that a data capturing speed of 130 Mbits/s could be maintained. / AFRIKAANSE OPSOMMING: Die SUNSAT massa geheue module is bestudeer, en toetse is daarop uigevoer om die vlug gereedheid te bepaal. Foute is gevind, en veranderinge moes aangebring word om korrekte werking te verseker. SUNSAT is gelanseer en die geheue module werk tot op datum nog korrek. Die geheue module se vlug gereedheid toetse is beskou as In voor studie vir die ontwerp van In tweede generasie geheue module. In Konseptueie massa stoor toestel struktuur is ontwerp. Hierdie tweede generasie geheue module, of geheue skyf is bedoel om op In tweede generasie SUNSAT, of SUNSAT 2 gebruik te word. FPGA's is die teiken tegnologie vir hierdie ontwerp en VHDL is gebruik om die ontwerp te realiseer. Hierdie hardeware beskrywingstaal word as In standaard aanvaar en kan in verskillende herprogrammeerbare tegnologieë gebruik word. Sirnulasies is gedoen om die funksionaliteit van die ontwerp te verifieer, en om te bepaal of die nodige data oordragstempo gehandhaaf kan word met herprogrammeerbare tegnologie. In Modulêre ontwerpsfilosofie is gevolg. Die geheue skyf is ontwerp sodat dit enige tipe en hoeveelheid geheue kan ondersteun sonder om groot veranderinge aan die ontwerp te doen. Die sirnulasies toon dat In data oordragstempo van 130 Mbits/s gehandhaafkan word.

Philosophiae Doctor - PhD / With the rapid rise in energy demand and ever-escalating environmental hazards, the need for transition from fossil fuel to renewable energy sources is of paramount importance, requiring better and efficient energy storage devices such as supercapacitors. Supercapacitors are energy storage devices with high power density and long cycle life, but relatively low energy density when compared to batteries. New and advanced electrode materials are required to improve the energy density requirements of next-generation supercapacitors. However, the search for new types of active materials to be used as supercapacitors' electrodes continues to be a tough challenge. Herein, ruthenium antimony oxide (RuSbO) and ruthenium antimony oxide graphene (RuSbO-G) were synthesized via the microwave-assisted method for the first time and tested as a possible electrode material for an asymmetric supercapacitor. Graphene oxide prepared by modified Hummer’s method was exfoliated at low temperature and used for the synthesis of RuSbO-G. / 2025

Graph Neural Networks (GNNs) have emerged as a robust model for machine learning, addressing complex graph-structured data, in contrast to traditional deep learning techniques primarily used for image and text data. However, the scalability of GNNs on large graphs with billions of nodes and trillions of edges remains a challenge. Existing approaches propose partitioning across distributed systems or employing single machines with GPU caching techniques during the sampling phase. While the former encounters issues related to maintenance costs and increased latency, the latter faces bottlenecks in data movement, resulting in inefficient resource utilization and suboptimal training. To address the limitations of single-machine techniques, we direct our attention to the sampling stage and introduce a novel approach utilizing the Samsung smartSSD computational storage device. This approach significantly reduces unnecessary data movement overhead and minimizes overall training time. Computational storage devices enable the offloading of computations to their computational units. In our method, we calculate the required sampling subset on its Field programmable gate array (FPGA) of the smartSSD and transfer it to the host DRAM. Our experimental section illustrates that our proposed solution, compared to the baseline MMAP sampling method, achieves a speedup of up to 9 times in terms of sampling time and 5 times in host DRAM utilization.

We develop a simplified one-dimensional numerical model that simulates the performance of thermoelectric generators (TEG). The model is based on the energy and electrical potential field equations. The Seebeck coefficient, thermal conductivity, electrical resistivity and Thomson coefficient of the TEG material are used to predict the harvested power. Bismuth-telluride is used as semiconductors materials of the TEG, which is the most commonly used material by industry. Experiments on three TEG modules were performed to validate the numerical model. A comparison with predicted levels of harvested energy based on the TEG specifications is also performed. The results show differences between the experimental and numerical values on one hand and the predicted ones on the other hand. The reason for these differences are discussed. A procedure to estimate the sensitivity of the harvested power to different inputs and TEG parameters is detailed. In the second part of the dissertation, we integrate a thermoelectric generator with an organic storage device. The performance of the integrated system for different values of load resistances and temperature gradients is determined. Finally, we demonstrate that power generated from a TEG is related to the flow rate in a pipe and can, thus, be used as a flow meter. Particularly, a dimensionless relation between the TEG's peak power and Reynolds number is determined. / Ph. D.

Thesis (MComm)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: This thesis describes the design and implementation of a data storage service. Many clients can be served simultaneously in an environment where processes execute on different physical machines and communicate via message passing primitives. The service is provided by two separate servers: one that functions at the disk block level and another that maintains files. A prototype system was developed first in the form of a simple file store. The prototype served two purposes: (1) it extended the single-user Oberon system to create a multiuser system suitable to support group work in laboratories, and (2) it provided a system that could be measured to obtain useful data to design the final system. Clients access the service from Oberon workstations. The Oberon file system (known as the Ceres file system) normally stores files on a local disk. This system was modified to store files on a remote Unix machine. Heavily used files are cached to improve the efficiency of the system. In the final version of the system disk blocks are cached, not entire files. In this way the disks used to store the data are unified and presented as a separate virtual block service to be used by file systems running on client workstations. The virtual block server runs on a separate machine and is accessed via a network. The simplicity of the block server is appealing and should in itself improve reliability. The main concern is efficiency and the goal of the project was to determine whether such a design can be made efficient enough to serve its purpose. / AFRIKAANSE OPSOMMING:Hierdie tesis omskryf die ontwerp en implementasie van 'n data stoor diens. Verskeie gebruikers word bedien deur die diens wat funksioneer in 'n verspreide omgewing: 'n omgewing waar prosesse uitvoer op verskillende masjiene en met mekaar kommunikeer met behulp van boodskappe wat rondgestuur word. Die diens word verskaf deur twee bedieners: die eerste wat funksioneer op 'n blok vlak en die ander wat lers onderhou. 'n Prototipe leer diens is ontwikkel deur middel van 'n basiese leer stoor. Die prototipe het twee funksies verrig: (1) die enkel gebruiker Oberon stelsel is uitgebrei na 'n veelvoudige gebruiker stelsel bruikbaar vir groepwerk in 'n laboratorium omgewing, en (2) 'n stelsel is verskaf wat betroubare en akkurate data kon verskaf vir die ontwerp van die finale stelsel. Oberon werkstasies word gebruik met die leer diens. Die Oberon leer stelsel (ook bekend as die Ceres leer stelsel) stoor normaalweg leers op 'n lokale skyf. Hierdie bestaande stelsel is verander om leers te stoor op 'n eksterne Unix masjien. Leers wat die meeste in gebruik is word in geheue aangehou vir effektiwiteits redes. Die finale weergawe van die stelsel berg skyf blokke in geheue, nie leers nie. Hierdie metode laat dit toe om data te stoor op 'n standaard metode, bruikbaar deur verskillende tipes leer stelsels wat uitvoer op verskeie gebruikers se werkstasies. Die virtuele blok stoor voer uit op 'n aparte masjien en is bereikbaar via 'n netwerk. Die eenvoudige ontwerp van die diens is opsigself aanloklik en behoort betroubaarheid te verbeter. Die hoof bekommernis is effektiwiteit en die hoofdoel van die projek was om te bepaal of hierdie ontwerp effektief genoeg gemaak kon word.

This thesis concerns a study of the application, and performance optimization, of standard lead-lag compensation techniques to improve the closed loop performance of a focus servo system for an optical data storage device. Only with proper application of these compensation techniques will it be possible to meet the sub-micrometer focus error tolerances while maintaining the stability of the closed loop system. The performance indices used in this optimization study are the Integral of the Squared Error (ISE), the Integral of the Absolute Error (IAE), and the Integral of the Time multiplied by the Absolute Error (ITAE) as defined below, with the error function e(t) being the focus error of the closed loop servo system in response to a step input. ISE= ∫OT e²(t) dt IAE= ∫OT / e(t) / dt ITAE= ∫OT t / e(t) / dt

M.Com. (Informatics) / Please refer to full text to view abstract