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In soil and rock mechanics, coupling effects between geomechanics field and fluid-flow field are important to understand many physical phenomena. Coupling effects in fluid-saturated porous media comes from the interaction between the geomechanics field and the fluid flow. Stresses subjected on the porous material result volumetric strains and fluid diffusion in the pores. In turn, pore pressure change cause effective stresses change that leads to the deformation of the geomechanics field. Coupling effects have been neglected in traditional geotechnical engineering and petroleum engineering however, it should not be ignored or simplified to increases reliability of the results. The coupling effect in porous media was theoretically established in the poroelasticity theory developed by Biot, and it has become a powerful theory for modeling three-dimensional consolidation type of problem. The analysis of the porous media with fully-coupled simulations based on the Biot's theory requires intensive computational effort due to the large number of interacting fields. Therefore, advanced computational techniques need to be exploited to reduce computational time. In order to solve the coupled problem, several techniques are currently available such as one-way coupling, partial-coupling, and full-coupling. The fully-coupled approach is the most rigorous approach and produces the most correct results. However, it needs large computational efforts because it solves the geomechanics and the fluid-flow unknowns simultaneously and monolithically. In order to overcome this limitation, staggered solution based on the Biot's theory is proposed and implemented using a modular approach. In this thesis, Biot's equations are implemented using a Finite Element method and/or Finite Difference method with expansion of nonlinear stress-strain constitutive relation and multi-phase fluid flow. Fully-coupled effects are achieved by updating the compressibility matrix and by using an additional source term in the conventional fluid flow equation. The proposed method is tested in multi-phase FE and FD fluid flow codes coupled with a FE geomechanical code and numerical results are compared with analytical solutions and published results. / Ph. D.

Lattice-based cryptography has generated considerable interest in the last two decades due toattractive features, including conjectured security against quantum attacks, strong securityguarantees from worst-case hardness assumptions and constructions of fully homomorphicencryption schemes. On the other hand, even though it is a crucial part of many lattice-basedschemes, Gaussian sampling is still lagging and continues to limit the effectiveness of this newcryptography. The first goal of this thesis is to improve the efficiency of Gaussian sampling forlattice-based hash-and-sign signature schemes. We propose a non-centered algorithm, with aflexible time-memory tradeoff, as fast as its centered variant for practicable size of precomputedtables. We also use the Rényi divergence to bound the precision requirement to the standarddouble precision. Our second objective is to construct Falcon, a new hash-and-sign signaturescheme, based on the theoretical framework of Gentry, Peikert and Vaikuntanathan for latticebasedsignatures. We instantiate that framework over NTRU lattices with a new trapdoor sampler.

" In the last decade, cloud computing became popular among companies for outsourcing some of their services. Companies use cloud services to store crucial information such as financial and client data. Cloud services are not only cost effective but also easier to manage since the companies avoid maintenance of servers. Although cloud has its advantages, maintaining the security is a big concern. Cloud services might not have any malicious intent, but attacks targeting cloud systems could easily steal vital data belong to the companies. The only protection that assures the security of the information is a strong encryption. However, these schemes only protects the information but prevent you to do any computation on the data. This was an open problem for more than 30 years and it has been solved recently by the introduction of the first fully homomorphic encryption (FHE) scheme by Gentry. The FHE schemes allow you to do arbitrary computation on an encrypted data by still preserving the encryption. Namely, the message is not revealed (decrypted) at any given time while computing the arbitrary circuit. However, the first FHE scheme is not practical for any practical application. Later, numerous research work has been published aiming at making fully homomorphic encryption practical for daily use, but still they were too inefficient to be used in everyday practical applications. In this dissertation we tackle the efficiency problems of fully homomorphic encryption (FHE) schemes. We propose two new FHE schemes that improve the storage requirement and runtime performance. The first scheme (Doröz, Hu and Sunar) reduces the size of the evaluation keys in existing NTRU based FHE schemes. In the second scheme (F-NTRU) we designed an NTRU based FHE scheme which is not only free of costly evaluation keys but also competitive in runtime performance. We further proposed two hardware accelerators to increase the performance of arithmetic operations underlying the schemes. The first accelerator is a custom hardware architecture for realizing the Gentry-Halevi fully homomorphic encryption scheme. This contribution presents the first full realization of FHE in hardware. The architecture features an optimized multi-million bit multiplier based on the Schönhage-Strassen multiplication algorithm. Moreover, a number of optimizations including spectral techniques as well as a precomputation strategy is used to significantly improve the performance of the overall design. The other accelerator is optimized for a class of reconfigurable logic for somewhat homomorphic encryption (SWHE) based schemes. Our design works as a co-processor: the most compute-heavy operations are offloaded to this specialized hardware. The core of our design is an efficient polynomial multiplier as it is the most compute-heavy operation of our target scheme. The presented architecture can compute the product of very-large polynomials more efficiently than software implementations on CPUs. Finally, to assess the performance of proposed schemes and hardware accelerators we homomorphically evaluate the AES and the Prince block ciphers. We introduce various optimizations including a storage-runtime trade-off. Our benchmarking results show significant speedups over other existing instantiations. Also, we present a private information retrieval (PIR) scheme based on a modified version of Doröz, Hu and Sunar’s homomorphic scheme. The scheme is capable of privately retrieving data from a database containing 4 billion entries. We achieve asymptotically lower bandwidth cost compared to other PIR schemes which makes it more practical. "

A pulsed fuel injector system was used to study flame structure, flame length, and emissions of ethylene jet diffusion flames over a range of injection times and duty-cycles with a variable air co-flow. In all cases the jet was completely shut off between pulses (fully-modulated) for varying intervals, giving both widely-spaced, non-interacting puffs and interacting puffs. Imaging of the luminosity from the flame revealed distinct types of flame structure and length, depending on the duration of the fuel injection interval. Flame lengths for isolated puffs (small injection times) were up to 83% less than steady state flames with the same injection velocities. With the addition of co-flow flame lengths grew to a maximum of 30% longer than flames without any co-flow. A scaling argument is also developed to predict the amount of co-flow that gives a 15% increase in mean flame length. Interacting flames with a small co-flow and small injection times (injection time = 5.475 ms) experienced flame length increases of up to 212% for a change in injection duty-cycle from 0.1 to 0.5. For interacting flames with long injection times (on time = 119 ms), essentially no change in flame length was noticeable over the same range of duty-cycles. Emission measurements suggest partial quenching of the reaction in isolated puffs with low duty-cycles and injection times (injection times less than 5.475 ms) resulting in high CO and UHC concentrations and low NO and NOx concentrations. With an increase in duty-cycle, the puffs began to interact and CO and UHC concentrations decreased while NO and NOx concentrations increased. For flames with injection times greater than 5.475 ms emission concentrations seem to be reasonably constant, with a slight increase in NO and NOx concentrations as the duty-cycle increased. Also the duty-cycle experienced in the vicinity of the probe is estimated and used as a scaling factor for the emission measurements.

This thesis introduces the Named-State Register File, a fine-grain, fully-associative register file. The NSF allows fast context switching between concurrent threads as well as efficient sequential program performance. The NSF holds more live data than conventional register files, and requires less spill and reload traffic to switch between contexts. This thesis demonstrates an implementation of the Named-State Register File and estimates the access time and chip area required for different organizations. Architectural simulations of large sequential and parallel applications show that the NSF can reduce execution time by 9% to 17% compared to alternative register files.

Thermal stream loadings from both natural and anthropogenic sources have significant relevance with respect to ecosystem health and water resources management, particularly in the context of future climate change. In recent years, there has been an increase in field-based research directed towards characterizing thermal energy transport exchange processes that occur at the surface water/groundwater interface of streams. In spite of this effort, relatively little work has been performed to simulate these exchanges and elucidate their roles in mediating surface water temperatures and to simultaneously take into account all the pertinent hydrological, meteorological and surface/variably-saturated subsurface processes. To address this issue, HydroGeoSphere, a fully-integrated surface/subsurface flow and transport model, was enhanced to include fully-integrated thermal energy transport. HydroGeoSphere can simulate water flow, evapotranspiration, and advective-dispersive heat and solute transport over the 2D land surface and water flow and heat and solute transport in 3D subsurface variably-saturated conditions. In this work, the new thermal capabilities of HydroGeoSphere are tested and verified by comparing HydroGeoSphere simulation results to those from a previous subsurface thermal groundwater injection study, and also by simulating an example of atmospheric thermal energy exchange. A proof of concept simulation is also presented which illustrates the ability of HydroGeoSphere to simulate fully-integrated surface/subsurface thermal energy transport. High-resolution 3D numerical simulations of a well-characterized reach of the Pine River in Ontario, Canada are also presented to demonstrate steady-state thermal energy transport in an atmosphere-groundwater-surface water system. The HydroGeoSphere simulation successfully matched the spatial variations in the thermal patterns observed in the river bed, the surface water and the groundwater. Transient simulations of the high-resolution Pine River domain are also presented. Diurnal atmospheric conditions were incorporated to illustrate the importance of fluctuations in atmospheric parameters on the entire hydrologic regime. The diurnal atmospheric input fluxes were found to not only change the temperatures of the surface and subsurface throughout the cycle, but also the magnitude and direction of the transfer of thermal energy between the surface and subsurface. Precipitation events were also simulated for the Pine River domain using three different rainfall rates. The surface temperatures responded quickly to the rainfall events, whereas the subsurface temperatures were slower to respond in regions where infiltration was not significant. A thermal energy signal from the precipitation event was evident in the subsurface, and dissipated once the rainfall ceased. This indicates that temperature can potentially be used as a tracer for hydrograph separation. The potential of a thermal energy tracer for hydrograph separation was investigated using HydroGeoSphere simulations of the Borden rainfall-runoff experiment. These results matched both measured and previous simulation results using a bromide tracer. The hydrograph separation results from the thermal energy tracer were sensitive to temperature conditions in the subsurface, although this sensitivity reduced considerably when the precipitation event and subsurface temperatures were significantly different. The contribution of each atmospheric component to thermal energy transport was investigated using the Pine River and Borden examples. Each atmospheric component was individually neglected from the simulation of both sites to investigate their impact on thermal energy transport. The results show that longwave radiation dominates the atmospheric inputs for the Borden example, whereas shortwave radiation dominates in the Pine River example. This indicates that the atmospheric contributions to the thermal energy distribution are site-specific and cannot be generalized. In addition, these results indicate that the atmospheric contributions should not be ignored; measuring atmospheric data in the field is an important component in developing an accurate thermal energy transport model. The addition of thermal energy transport to HydroGeoSphere provides a valuable tool for investigating the impact of anthropogenic and non-anthropogenic changes to the atmospheric and hydrological thermal energy system. This computational framework can be used to provide quantitative guidance towards establishing the conditions needed to maintain a healthy ecosystem.

Thermal stream loadings from both natural and anthropogenic sources have significant relevance with respect to ecosystem health and water resources management, particularly in the context of future climate change. In recent years, there has been an increase in field-based research directed towards characterizing thermal energy transport exchange processes that occur at the surface water/groundwater interface of streams. In spite of this effort, relatively little work has been performed to simulate these exchanges and elucidate their roles in mediating surface water temperatures and to simultaneously take into account all the pertinent hydrological, meteorological and surface/variably-saturated subsurface processes. To address this issue, HydroGeoSphere, a fully-integrated surface/subsurface flow and transport model, was enhanced to include fully-integrated thermal energy transport. HydroGeoSphere can simulate water flow, evapotranspiration, and advective-dispersive heat and solute transport over the 2D land surface and water flow and heat and solute transport in 3D subsurface variably-saturated conditions. In this work, the new thermal capabilities of HydroGeoSphere are tested and verified by comparing HydroGeoSphere simulation results to those from a previous subsurface thermal groundwater injection study, and also by simulating an example of atmospheric thermal energy exchange. A proof of concept simulation is also presented which illustrates the ability of HydroGeoSphere to simulate fully-integrated surface/subsurface thermal energy transport. High-resolution 3D numerical simulations of a well-characterized reach of the Pine River in Ontario, Canada are also presented to demonstrate steady-state thermal energy transport in an atmosphere-groundwater-surface water system. The HydroGeoSphere simulation successfully matched the spatial variations in the thermal patterns observed in the river bed, the surface water and the groundwater. Transient simulations of the high-resolution Pine River domain are also presented. Diurnal atmospheric conditions were incorporated to illustrate the importance of fluctuations in atmospheric parameters on the entire hydrologic regime. The diurnal atmospheric input fluxes were found to not only change the temperatures of the surface and subsurface throughout the cycle, but also the magnitude and direction of the transfer of thermal energy between the surface and subsurface. Precipitation events were also simulated for the Pine River domain using three different rainfall rates. The surface temperatures responded quickly to the rainfall events, whereas the subsurface temperatures were slower to respond in regions where infiltration was not significant. A thermal energy signal from the precipitation event was evident in the subsurface, and dissipated once the rainfall ceased. This indicates that temperature can potentially be used as a tracer for hydrograph separation. The potential of a thermal energy tracer for hydrograph separation was investigated using HydroGeoSphere simulations of the Borden rainfall-runoff experiment. These results matched both measured and previous simulation results using a bromide tracer. The hydrograph separation results from the thermal energy tracer were sensitive to temperature conditions in the subsurface, although this sensitivity reduced considerably when the precipitation event and subsurface temperatures were significantly different. The contribution of each atmospheric component to thermal energy transport was investigated using the Pine River and Borden examples. Each atmospheric component was individually neglected from the simulation of both sites to investigate their impact on thermal energy transport. The results show that longwave radiation dominates the atmospheric inputs for the Borden example, whereas shortwave radiation dominates in the Pine River example. This indicates that the atmospheric contributions to the thermal energy distribution are site-specific and cannot be generalized. In addition, these results indicate that the atmospheric contributions should not be ignored; measuring atmospheric data in the field is an important component in developing an accurate thermal energy transport model. The addition of thermal energy transport to HydroGeoSphere provides a valuable tool for investigating the impact of anthropogenic and non-anthropogenic changes to the atmospheric and hydrological thermal energy system. This computational framework can be used to provide quantitative guidance towards establishing the conditions needed to maintain a healthy ecosystem.

Fully conjugated heterocyclic aromatic rod-like polymer poly-p-phenylene- benzobisoxazole (PBO) and coil-like poly-(3-hexylthiophene) (P3HT) were applied as opto-electronically active layer. The two polymers mixed with nano-carbon particles, having excellent optical absorption and electric conductivity, of [6,6]-phenyl C61-butyric acid methyl ester (PCBM) or esterified multi-wall carbon nano-tube (MWNT-COOC10H21) as well as a hole transporting layer of PEDOT:PSS. Photovoltaic (PV) cells of indium-tin-oxide (ITO)/PEDOT:PSS/nano-carbon particle:fully conjugated polymer/Al were fabricated for optical and electrical characterizations. Tri-layered structure of ITO/PEDOT:PSS/PBO/PCBM/Al produced a straight current-voltage relation showing no PV effects. Upon changing the active layer into PCBM doped P3HT layer (PCBM:P3HT), it produced good PV effects suggesting that the doped layer had a penetrating network to facilitate the PV effects. When PCBM or MWNT-COOC10H21 was doped into P3HT, the device PV effects were increased significantly with nano-carbon particle concentration. The direct-current electric conductivity parallel to the film surface (£m¡ü)was increased with the nano-carbon particle concentration. By changing the thickness of hole transporting PEDOT:PSS and of opto-electronically active layers, it was found that when the PEDOT:PSS layer was decreased from 90 nm to 32 nm, there was a slight increase of PV cell efficiency. The active layer of PCBM:P3HT with a thickness of 99 nm had the best optical absorption and charge transport leading to an increase of PV cell efficiency.

Fully homomorphic encryption (FHE) allows for computation of arbitrary func- tions on encrypted data by a third party, while keeping the contents of the encrypted data secure. This area of research has exploded in recent years following Gentry’s seminal work. However, the early realizations of FHE, while very interesting from a theoretical and proof-of-concept perspective, are unfortunately far too inefficient to provide any use in practice. The bootstrapping step is the main bottleneck in current FHE schemes. This step refreshes the noise level present in the ciphertexts by homomorphically evaluating the scheme’s decryption function over encryptions of the secret key. Bootstrapping is necessary in all known FHE schemes in order to allow an unlimited amount of computation, as without bootstrapping, the noise in the ciphertexts eventually grows to a point where decryption is no longer guaranteed to be correct. In this work, we present two new bootstrapping algorithms for FHE schemes. The first works on packed ciphertexts, which encrypt many bits at a time, while the second works on unpacked ciphertexts, which encrypt a single bit at a time. Our algorithms lie at the heart of the fastest currently existing implementations of fully homomorphic encryption for packed ciphertexts and for single-bit encryptions, respectively, running hundreds of times as fast for practical parameters as the previous best implementations.