Coset Coding to Extend the Lifetime of Non-Volatile Memory

<p>Modern computing systems are increasingly integrating both Phase Change Memory (PCM) and Flash memory technologies into computer systems being developed today, yet the lifetime of these technologies is limited by the number of times cells are written. Due to their limited lifetime, PCM and Flash may wear-out before other parts of the system. The objective of this dissertation is to increase the lifetime of memory locations composed of either PCM or Flash cells using coset coding. </p><p>For PCM, we extend memory lifetime by using coset coding to reduce the number of bit-flips per write compared to un-coded writes. Flash program/erase operation cycle degrades page lifetime; we extend the lifetime of Flash memory cells by using coset coding to re-program a page multiple times without erasing. We then show how coset coding can be integrated into Flash solid state drives.</p><p>We ran simulations to evaluate the effectiveness of using coset coding to extend PCM and Flash lifetime. We simulated writes to PCM and found that in our simulations coset coding can be used to increase PCM lifetime by up to 3x over writing un-coded data directly to the memory location. We extended the lifetime of Flash using coset coding to re-write pages without an intervening erase and were able to re-write a single Flash page using coset coding more times than when writing un-coded data or using prior coding work for the same area overhead. We also found in our simulations that using coset coding in a Flash SSD results in higher lifetime for a given area overhead compared to un-coded writes.</p>Dissertatio

The Deep Space Network: A Radio Communications Instrument for Deep Space Exploration

The primary purpose of the Deep Space Network (DSN) is to serve as a communications instrument for deep space exploration, providing communications between the spacecraft and the ground facilities. The uplink communications channel provides instructions or commands to the spacecraft. The downlink communications channel provides command verification and spacecraft engineering and science instrument payload data

Cryptography based on the Hardness of Decoding

This thesis provides progress in the fields of for lattice and coding based cryptography. The first contribution consists of constructions of IND-CCA2 secure public key cryptosystems from both the McEliece and the low noise learning parity with noise assumption. The second contribution is a novel instantiation of the lattice-based learning with errors problem which uses uniform errors

Alterations within the structural hierarchy of parchment induced by damage mechanisms

Collagen plays an important role in many biological tissues, including skin, which, once dried and treated, forms parchment and leather. The structural alterations that occur in collagenous materials due to X-ray radiation damage, fluctuation of relative humidity, and mechanical deformation (with a special focus on historical parchment) are the focus of this thesis. The primary aim of this thesis is to investigate major structural changes to collagen within parchment when exposed to inappropriate levels of relative humidity during conservation treatments, and cyclic-humidity during long-term storage in archives, museums and libraries. This study led to the discovery that each parchment sample reacted to the application and removal of moisture in a different way, indicating the fundamental need to treat individual parchment documents as in-homogeneous materials. This thesis investigates the changes that fibrillar collagen undergoes and describes the creation of computational models capable of reproducing the X-ray diffraction patterns for collagen. Previous structural models have been created that sufficiently account for native collagen, however, models created as part of this thesis succeed where previous models have failed in explaining the X-ray diffraction patterns collected from damaged collagen. This study provided the opportunity to contribute towards a large-scale international collaborative project on the hugely important historical resource, the Domesday Book. X-ray diffraction was used to provide unprecedented analysis of Domesday Book samples, providing a structural survey at a molecular level. This analysis produced the conclusion that the majority of samples displayed the presence of collagen axial structure, and were generally of a degraded state as a consequence of the method used to source them the samples were scrapings from the surface, which was less intact than the bulk of the parchment.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Alterations within the structural hierarchy of parchment induced by damage mechanisms

Collagen plays an important role in many biological tissues, including skin, which, once dried and treated, forms parchment and leather. The structural alterations that occur in collagenous materials due to X-ray radiation damage, fluctuation of relative humidity, and mechanical deformation (with a special focus on historical parchment) are the focus of this thesis. The primary aim of this thesis is to investigate major structural changes to collagen within parchment when exposed to inappropriate levels of relative humidity during conservation treatments, and cyclic-humidity during long-term storage in archives, museums and libraries. This study led to the discovery that each parchment sample reacted to the application and removal of moisture in a different way, indicating the fundamental need to treat individual parchment documents as in-homogeneous materials. This thesis investigates the changes that fibrillar collagen undergoes and describes the creation of computational models capable of reproducing the X-ray diffraction patterns for collagen. Previous structural models have been created that sufficiently account for native collagen, however, models created as part of this thesis succeed where previous models have failed in explaining the X-ray diffraction patterns collected from damaged collagen. This study provided the opportunity to contribute towards a large-scale international collaborative project on the hugely important historical resource, the Domesday Book. X-ray diffraction was used to provide unprecedented analysis of Domesday Book samples, providing a structural survey at a molecular level. This analysis produced the conclusion that the majority of samples displayed the presence of collagen axial structure, and were generally of a degraded state as a consequence of the method used to source them the samples were scrapings from the surface, which was less intact than the bulk of the parchment