This work formulates and analyzes a new coupled finite volume (FV) and discontinuous Galerkin (DG) method for convection-diffusion problems. DG methods, though costly, have proved to be accurate for solving convection-diffusion problems and capable of handling discontinuous and tensor coefficients. FV methods have proved to be very efficient but they are only of first order accurate and they become ineffective for tensor coefficient problems. The coupled method takes advantage of both the accuracy of DG methods in the regions containing heterogeneous coefficients and the efficiency of FV methods in other regions. Numerical results demonstrate that this coupled method is able to resolve complicated coefficient problems with a decreased computational cost compared to DG methods. This work can be applied to problems such as the transport of contaminant underground, the CO 2 sequestration and the transport of cells in the body.

Biofouling is a major impediment for the application of reverse osmosis filtration and nanofiltration in water and wastewater treatment as well as seawater desalination. In this study, a novel biofouling control strategy of using D-amino acids to interfere with biofilm formation was evaluated. Impact of D-amino acids on the surface attachment and biofilm formation of Pseudomonas aeruginosa was investigated in batch and continuous flow filtration systems. All 19 D-amino acids demonstrated inhibitive effects on P. aeruginosa biofilm formation. In particular, D-tyrosine was found to strongly inhibit P. aeruginosa attachment and biofilm formation on an NF membrane. When continuously supplemented to the membrane feed water in a bench scale nanofiltration system, it prohibited irreversible biofouling of the NF membrane at concentrations as low as 3 μM. The effectiveness of biofilm control by these D-amino acids seems to strongly depend on the ratio of D-amino acid concentration to bacterial cell number.

Networked real-time systems (NRSs) are pervasive in the real world, and many of them work in an open environment with varying workload. Quality of service (QoS) of NRSs is closely related to the provision of the system resources for servingthe real-time tasks. To provide guarantees of QoS in NRSs, the system resources should be allocated to the real-time tasks in adaptation to the workload variations so that the desired system performance is obtained, referred to as QoS control.This thesis is concerned with the design of dynamic resource allocation schemes for QoS control in three typical NRSs. In the first part, we propose dynamic computing capacity planning schemes for processor utilization control in the distributed real-time systems, and for energy minimization with request response time guarantees in the server clusters. To handle the workload variations, we model the workload uncertainties as the parameters in the system models and use the system performance as online feedback to predict these parameters as precise as possible. Then the optimal computing capacities are provided to serve the real-time tasks in these systems online. Experimental/simulation results demonstrate effectiveness of the proposed schemes for QoS control in comparisons with the existing approaches. In the second part, we propose a dynamic network scheduling scheme for networked control systems (NCSs), typical NRSs with network bandwidth as a critical system resource. The proposed scheduling scheme can properly allocate the network bandwidth to the applications in NCSs so that the good real-time performance can be achieved. / Les systèmes temps-réel en réseau (NRSs) sont de plus en plus utilisés, et beaucoup d'entre eux fonctionnent dans un environnement ouvert aux charges variables. La Qualité de Service (QoS) des NRSs dépend des ressources systèmes pour répondre aux taches en temps-réel. Pour garantir la QoS, les ressources système doivent être allouées dynamiquement, en s'adaptant aux variations de charge, ceci dans le but d'atteindre les performances désirées.Cette thèse traite de la conceptions de méthodes d'allocation dynamique des ressources dans le but d'assurer la QoS dans le cas de 3 NRSs représentatifs. Nous commencerons pas proposer des méthodes de plannification de capacités pour le contrôle de l'utilisation du processeur dans les systèmes distribués, à coup énergétique minimal, avec temps de réponse garanti. Pour supporter les variations de charge, nous utilisons les performances du système pour prédire l'évolution de la charge à venir aussi précisement que possible. Ensuite, les ressources optimales sont libéréespour répondre aux besoins en temp-réel. Les resultats des expérimentations / simulations démontrent l'efficacité de ces méthodes sur le contrôle de la QoS, en comparaison à d'autres approches existantes. Dans un second temps, nous proposerons une méthodologie de séquençage réseau dynamique pour les systèmes controlés en réseau (NCSs), un NRS commun dépendant fortement de la bande passante du réseau. La méthodologie proposée peut correctement allouer la bande passante aux applications du NCS de sorte que de bonnesperformances soient atteintes.

This research implements the first Houston/Galveston area hurricane risk assessment of bridges for multiple failure modes: bridge deck uplift and bridge scour. Due to recent hurricane damage of bridges, emergency managers need to understand the potential state of the bridge network immediately following a storm for effective mitigation and post-event planning. To that end, this study builds a new database of bridge information necessary for vulnerability modeling, adapts current deterministic models of bridge deck uplift and scour for a probabilistic framework and expands the scour models to include a qualitative estimate for embankment scour. The study area bridges are tested under various hurricane scenario events to reveal the likelihood of damage. Potential applications include retrofit prioritization, real-time spatial damage modeling and better informed preparation. By understanding the risk hurricanes pose to the bridge system, emergency officials can better plan rescue and recovery efforts before a storm impacts the Texas coast.

Smartphone applications(apps) often run with full privileges to access the network and sensitive local resources, making it difficult for remote systems to have any trust in the provenance of network connections they receive. Even within the phone, different apps with different privileges can communicate with one another, allowing one app to trick another into improperly exercising its privileges (a confused deputy attack). This thesis presents two new security mechanisms built into the Android operating system to address these issues. First, the call chain of all interprocess communications are tracked, allowing an app the choice of operating with the diminished privileges of its callers or to act explicitly on its own behalf. Additionally, a lightweight signature scheme allows any app to create a signed statement that can be verified anywhere inside the phone. Both of these mechanisms are reflected in network RPCs, allowing remote endpoints visibility into the state of the phone when an RPC is made.

This thesis describes the design and the optimization of a low overhead, high performance variable latency carry select adder. Previous researchers believed that the traditional adder has reached the theoretical speed bound. However, a considerable portion of hardware resources of the traditional adder is only used in the worst case. Based on this observation, variable latency adders have been proposed to improve on the theoretical limit, but such adders incur significant area overhead. By combining previous variable latency adders with carry select addition, this work describes a novel variable latency carry select adder. Applying carry select addition in the variable latency adder design significantly reduces the area overhead and increases its performance. This variable latency adder is faster and smaller than previous variable latency adders. Furthermore, this variable latency adder can be optimized to be faster and smaller than the fastest adder generated by the Synopsys DesignWare building block IP.

The details of the aerodynamics of flapping flight continue to pose a considerable challenge to a complete understanding of flight. Advanced computational fluid mechanics technology coupled with experimental data offers a unique perspective into these aerodynamics. The difficulty of computing such complex aerodynamics is mostly related to the presence of moving and deforming solid surfaces. The finite element method with the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) formulation, which was developed by the Team for Advanced Flow Simulation and Modeling for the computation of flow problems involving moving boundaries and interfaces, is well-suited for this type of problem. The DSD/SST method is further enhanced with a variational multiscale turbulence model and other special techniques, which were developed in the context of the DSD/SST method for flapping flight computations and involve temporal NURBS basis functions. These techniques are applied to the computation of locust flapping flight, where the prescribed motion and deformation of the wings are based on digital data extracted from wind tunnel experiments. This forms a foundation upon which further study may reveal additional insight into flapping flight aerodynamics.

Atomic force microscope (AFM) is an important tool for measuring the topographical and other properties of a sample with nanometer resolution. The cantilever probe of the AFM is influenced by nonlinear interaction forces which act between the probe and the sample. For certain non-standard excitation conditions, this can result in bifurcations in the probe's response. This work numerically examines a period-doubling bifurcation observed to occur for interactions with soft materials. The influence of the sample properties and other conditions on the bifurcation is studied and a method is proposed for sample material characterization. The identified values from simulated 1-D and 2-D scans agree well with the true values. The proposed method does not require the use of special probes and it uses the control algorithm for traditional tapping mode AFM with minor modification. This proposed method could also achieve high scan speeds and prevent strong, destructive interaction forces.

In this research, I derive a refined asymptotic expression for the eigenvalues, [Special characters omitted.] , of the operator matrix from the telegrapher's equation to accuracy O (1/ n 2). First, the expression for the "shooting function" is refined to O (1/ n 2) using a "fake potential" and a Neumann series. Then, this expression for the "shooting function" is used to refine the expressions for the eigenvalues. This refinement of the previously published results of accuracy O (1/| n |) enables the inverse spectral problem (recovering unknown resistance) to be solved in numerical experiments, using Fourier series. One application of this recovery process would be to find a fault in the insulation of a submarine telegraph cable without having to physically inspect every inch of the cable.

This thesis presents a framework for a radar-based flood alert system (FAS) for the Oyster Creek Watershed to aid the City of Sugar Land in flood forecasting. The motivation for using this particular system stems from a radar's ability to provide flood warning lead-time when calibrated with available gauge information. This study follows a typical workflow in analyzing watersheds, which involves converting excess rainfall to runoff, then converting the resulting flow rates to polygons that show water levels. This thesis also introduces the Flood Warning Indicator (FWI) as a component of Sugar Land's FAS. FWI only uses radar rainfall to portray potential flooding problems within the watershed through GIS mapping, which is helpful when gauge information is unavailable. Having a significant role in the communication of flood information, FWI may be applied in other areas that lack the resources to build extensive gauge networks for flood monitoring and radar calibration.