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1	Designing Secure and Robust Distribted and Pervasive Systems with Error Correcting Codes Paul, Arnab 11 February 2005 (has links) This thesis investigates the role of error-correcting codes in Distributed and Pervasive Computing. The main results are at the intersection of Security and Fault Tolerance for these environments. There are two primary areas that are explored in this thesis. 1. We have investigated protocols for large scale fault tolerant secure distributed storage. The two main concerns here are security and redundancy. In one arm of this research we developed SAFE, a distributed storage system based on a new protocol that offers a two-in-one solution to fault-tolerance and confidentiality. This protocol is based on cryptographic properties of error correction codes. In another arm, we developed esf, another prototype distributed persistent storage; esf facilitates seamless hardware extension of storage units, high resilience to loads and provides high availability. The main ingredient in its design is a modern class of erasure codes known as the {em Fountain Codes}. One problem in such large storage is the heavy overhead of the associated fingerprints needed for checking data integrity. esf deploys a clever integrity check mechanism by use of a data structure known as the {em Merkle Tree} to address this issue. 2. We also investigated the design of a new remote authentication protocol. Applications over long range wireless would benefit quite a bit from this design. We designed and implemented LAWN, a lightweight remote authentication protocol for wireless networks that deploys a randomized approximation scheme based on Error correcting codes. We have evaluated in detail the performance of LAWN; while it adds very low overhead of computation, the savings in bandwidth and power are quite dramatic. Authentication protocol Large scale storage Distributed computing Security Ubiquitous computing Computer security Fault-tolerant computing Authentication
2	Hydrogen Production and Storage Optimization based on Technical and Financial Conditions : A study of hydrogen strategies focusing on demand and integration of wind power. / Optimering av vätgasproduktion och lagring utifrån tekniska och ekonomiska förutsättningar : En studie av vätgasstrategier med fokus på efterfrågan och integration av vindkraft. Langels, Hanna, Syrjä, Oskar January 2021 (has links) There has recently been an increased interest in hydrogen, both as a solution for seasonal energy storage but also for implementations in various industries and as fuel for vehicles. The transition to a society less dependent on fossil fuels highlights the need for new solutions where hydrogen is predicted to play a key role. This project aims to investigate technical and economic outcomes of different strategies for production and storage of hydrogen based on hydrogen demand and source of electricity. This is done by simulating the operation of different systems over a year, mapping the storage level, the source of electricity, and calculating the levelized cost of hydrogen (LCOH). The study examines two main cases. The first case is a system integrated with offshore wind power for production of hydrogen to fuel the operations in the industrial port Gävle Hamn. The second case examines a system for independent refueling stations where two locations with different electricity prices and traffic flows are analyzed. Factors such as demand, electricity prices, and component costs are investigated through simulating cases as well as a sensitivity analysis. Future potential sources of income are also analyzed and discussed. The results show that using an alkaline electrolyzer (AEL) achieves the lowest LCOH while PEM electrolyzer is more flexible in its operation which enables the system to utilize more electricity from the offshore wind power. When the cost of wind electricity exceeds the average electricity price on the grid, a higher share of wind electricity relative to electricity from the grid being utilized in the production results in a higher LCOH. The optimal design of the storage depends on the demand, where using vessels above ground is the most beneficial option for smaller systems and larger systems benefit financially from using a lined rock cavern (LRC). Hence, the optimal design of a system depends on the demand, electricity source, and ultimately on the purpose of the system. The results show great potential for future implementation of hydrogen systems integrated with wind power. Considering the increased share of wind electricity in the energy system and the expected growth of the hydrogen market, these are results worth acknowledging in future projects. Hydrogen hydrogen energy system hydrogen production hydrogen storage large-scale storage underground storage vessels LRC hydrogen application hydrogen strategies hydrogen transition offshore wind energy electricity grid electricity price volatile electricity prices renewable energy hydrogen refueling station hydrogen port green hydrogen hydrogen trucks hydrogen forklifts fuel cells electrolysis alkaline electrolyzer PEM electrolyzer levelized cost of hydrogen LCOH Vätgas vätgassystem vätgasproduktion vätgaslagring storskalig vätgaslagring bergrum vätgasapplikationer vätgasstrategi vätgasomställning grön omställning havsbaserad vindkraft volatila elpriser elnätet förnybar energi vätgastankstation vätgasmack vätgashamn grön vätgas vätgaslastbilar vätgastruckar bränsleceller elektrolys alkalisk elektrolysör PEM elektrolysör Elektroteknik och elektronik

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Designing Secure and Robust Distribted and Pervasive Systems with Error Correcting Codes