Modern data centers host hundreds of thousands of servers to achieve economies of scale. Such a huge number of servers create challenges for the data center network (DCN) to provide proportionally large bandwidth. In addition, the deployment of virtual machines (VMs) in data centers raises the requirements for efficient resource allocation and find-grained resource sharing. Further, the large number of servers and switches in the data center consume significant amounts of energy. Even though servers become more energy efficient with various energy saving techniques, DCN still accounts for 20% to 50% of the energy consumed by the entire data center. The objective of this dissertation is to enhance DCN performance as well as its energy efficiency by conducting optimizations on both host and network sides. First, as the DCN demands huge bisection bandwidth to interconnect all the servers, we propose a parallel packet switch (PPS) architecture that directly processes variable length packets without segmentation-and-reassembly (SAR). The proposed PPS achieves large bandwidth by combining switching capacities of multiple fabrics, and it further improves the switch throughput by avoiding padding bits in SAR. Second, since certain resource demands of the VM are bursty and demonstrate stochastic nature, to satisfy both deterministic and stochastic demands in VM placement, we propose the Max-Min Multidimensional Stochastic Bin Packing (M3SBP) algorithm. M3SBP calculates an equivalent deterministic value for the stochastic demands, and maximizes the minimum resource utilization ratio of each server. Third, to provide necessary traffic isolation for VMs that share the same physical network adapter, we propose the Flow-level Bandwidth Provisioning (FBP) algorithm. By reducing the flow scheduling problem to multiple stages of packet queuing problems, FBP guarantees the provisioned bandwidth and delay performance for each flow. Finally, while DCNs are typically provisioned with full bisection bandwidth, DCN traffic demonstrates fluctuating patterns, we propose a joint host-network optimization scheme to enhance the energy efficiency of DCNs during off-peak traffic hours. The proposed scheme utilizes a unified representation method that converts the VM placement problem to a routing problem and employs depth-first and best-fit search to find efficient paths for flows.

Due to the expanding aging population, Masters sport is becoming an increasingly popular activity for older adults (Weir et al., 2010). However, few resources are available to support lifelong sport adherence for middle-aged and older adults in competitive sport, or Masters athletes (MAs). The purpose of the thesis was to explore how MAs apply deliberate psychological strategies as a support to enhance their performance, experience, or adherence to the adult sport lifestyle. It also explored how mental performance consultants (MPCs) viewed the application of sport psychology to MAs, including content to which skills/strategies could be applied, and delivery approaches. In Manuscript 1, semi-structured interviews were conducted with eight Canadian MAs (Mage = 51, range 38-62; 3 males, 5 females) from 12 sports (10 individual, 2 team) to explore how they applied psychological skills/strategies as a support to the Masters sport experience. Data were thematically analyzed (Braun & Clark, 2012) deductively (Weinberg & Gould, 2015) and inductively. The results demonstrated that MAs used traditional mental skills predominantly to enhance performance, while novel Masters-specific skills were used to maintain sport adherence. MAs promptly illustrated sport psychology content, but were rather limited when discussing their methods/techniques. In Manuscript 2, five two-person semi- structured group interviews were pursued with ten professional Canadian MPCs (8 women, 2 men) who had experience consulting MAs. These interviews explored the content consultants delivered to MAs and whether there were implications of specific adult attributes associated with service delivery. Data were thematically analyzed (Braun & Clark, 2012) inductively. The results showed MPCs’ perceptions on psychological content they believed was highly pertinent in their consulting practice with MAs. Specifically, they described targeted content related to performance readiness, prioritizing sport, protecting/recovering sport enjoyment, and aging/self-compassionate considerations. MPCs also highlighted nuances related to approaches to consultation with adult sportspersons and the delivery of psychological services to MAs. In both studies with the MAs and the MPCs, interviewees described various barriers and constraints that influenced approaches to consultation and service delivery. Altogether, the corroborative results from both studies suggest the benefits of psychological support services for MAs, the use of MPCs’ services and expertise as an additional support to maintain lifelong sport activity, and provide a formative guide for content and approaches to delivery with the Masters clientele.

Respiratory muscle training (RMT) has been shown to improve exercise tolerance during a wide range of exercise modalities and durations of activity (McConnell & Romer, 2004b). However, there is a limited amount of research characterising the influence of RMT in specific athletic populations, or examining any sport-specific factors that may influence the benefits of RMT. Hence, the purpose of this dissertation was to evaluate the application of RMT in competitive rowers and to explore methods of optimising this to rowing. Results: Inspiratory muscle training (IMT) increased inspiratory muscle strength (~20-29%; p < 0.05) and attenuated inspiratory muscle fatigue (~8-28%; p < 0.05) during time trial performance in club-level and elite rowers. However, only in the club-level oarsmen was IMT associated with a measurable improvement in rowing performance (2.7% increase in mean power; p < 0.05). Expiratory muscle training (EMT) provided no ergogenic effect, and concurrent EMT and IMT did not enhance performance above that seen with IMT alone. IMT loads performed at 60-70% of maximal inspiratory mouth pressure (PImax) were equivalent to the widely used 30 repetition maximum, which is higher than reported for non-rowers (Caine & McConnell, 1998a); further, a load of 60% PImax was sufficient to activate the inspiratory muscle metaboreflex, as evidenced by a time-dependent rise in heart rate (70.1 ± 13.2 to 98.0 ± 22.8 bpm; p < 0.05) and mean arterial blood pressure (92.4 ± 8.5 to 99.7 ± 10.1 mmHg; p < 0.05). Higher and lower inspiratory loads did not activate the metaboreflex. Assessments of flow, pressure and volume in rowing relevant postures revealed no significant impairments, but optimal function occurred in the most upright postures. Conclusions: These data support the application of IMT, but not EMT, in elite and sub-elite rowers, and suggest that a load of 60-70% of PImax provides metaboreflex activation during loading. Further, the data do not support a requirement to undertake IMT in rowing relevant postures.

Wireless communication systems have undergone fast development in recent years. Based on GSM/EDGE and UMTS/HSPA, the 3rd Generation Partnership Project (3GPP) specified the Long Term Evolution (LTE) standard to cope with rapidly increasing demands, including capacity, coverage, and data rate. To achieve this goal, several key techniques have been adopted by LTE, such as Multiple-Input and Multiple-Output (MIMO), Orthogonal Frequency-Division Multiplexing (OFDM), and heterogeneous network (HetNet). However, there are some inherent drawbacks regarding these techniques. Direct conversion architecture is adopted to provide a simple, low cost transmitter solution. The problem of I/Q imbalance arises due to the imperfection of circuit components; the orthogonality of OFDM is vulnerable to carrier frequency offset (CFO) and sampling frequency offset (SFO). The doubly selective channel can also severely deteriorate the receiver performance. In addition, the deployment of Heterogeneous Network (HetNet), which permits the co-existence of macro and pico cells, incurs inter-cell interference for cell edge users. The impact of these factors then results in significant degradation in relation to system performance. This dissertation aims to investigate the key techniques which can be used to mitigate the above problems. First, I/Q imbalance for the wideband transmitter is studied and a self-IQ-demodulation based compensation scheme for frequency-dependent (FD) I/Q imbalance is proposed. This combats the FD I/Q imbalance by using the internal diode of the transmitter and a specially designed test signal without any external calibration instruments or internal low-IF feedback path. The instrument test results show that the proposed scheme can enhance signal quality by 10 dB in terms of image rejection ratio (IRR). In addition to the I/Q imbalance, the system suffers from CFO, SFO and frequency-time selective channel. To mitigate this, a hybrid optimum OFDM receiver with decision feedback equalizer (DFE) to cope with the CFO, SFO and doubly selective channel. The algorithm firstly estimates the CFO and channel frequency response (CFR) in the coarse estimation, with the help of hybrid classical timing and frequency synchronization algorithms. Afterwards, a pilot-aided polynomial interpolation channel estimation, combined with a low complexity DFE scheme, based on minimum mean squared error (MMSE) criteria, is developed to alleviate the impact of the residual SFO, CFO, and Doppler effect. A subspace-based signal-to-noise ratio (SNR) estimation algorithm is proposed to estimate the SNR in the doubly selective channel. This provides prior knowledge for MMSE-DFE and automatic modulation and coding (AMC). Simulation results show that this proposed estimation algorithm significantly improves the system performance. In order to speed up algorithm verification process, an FPGA based co-simulation is developed. Inter-cell interference caused by the co-existence of macro and pico cells has a big impact on system performance. Although an almost blank subframe (ABS) is proposed to mitigate this problem, the residual control signal in the ABS still inevitably causes interference. Hence, a cell-specific reference signal (CRS) interference cancellation algorithm, utilizing the information in the ABS, is proposed. First, the timing and carrier frequency offset of the interference signal is compensated by utilizing the cross-correlation properties of the synchronization signal. Afterwards, the reference signal is generated locally and channel response is estimated by making use of channel statistics. Then, the interference signal is reconstructed based on the previous estimate of the channel, timing and carrier frequency offset. The interference is mitigated by subtracting the estimation of the interference signal and LLR puncturing. The block error rate (BLER) performance of the signal is notably improved by this algorithm, according to the simulation results of different channel scenarios. The proposed techniques provide low cost, low complexity solutions for LTE and beyond systems. The simulation and measurements show good overall system performance can be achieved.

There is a growing interest in the field of Dielectric Elastomer Actuators (DEAs).A DEA consists of a thin DE lm coated with a compliant electrode. It expandsin planar directions and contracts in thickness under a driving voltage. Becauseof the similar actuation capability compared with human muscles, it is oftenreferred as artificial muscle. One possible application is to integrate the DEA inwearable devices for tremor suppression. In this thesis, the development of theDEA has been advanced towards this application in three aspects: performanceenhancement, modelling accuracy and self-sensing control. The results presented demonstrate that the combination of pre-strain and motion constraining enhances the force output of the DEA significantly but it also leads to the pre-mature electric breakdown that shortens the operational life. This drawback was suppressed by optimising the electrode configuration to avoid the electrically weak regions with low thickness across the DE lm, together with the lead contact o the active electrode region. The durability of the enhanced DEA was therefore improved significantly. Polyacrylate, a commonly used DE, was characterised for dynamic mechanical loading and electrical actuation. The conventional Kelvin-Voigt model was proved to be deficient in simulating the viscoelastic behaviour of polyacrylate in the frequency domain. The error in modelling was substantially reduced using a higher material model that contains multiple spring-damper combinations. It allows the system dynamics to be shaped over frequency ranges. A detailed procedure was given to guide the parameter identification in higher order material model. A novel self-sensing mechanism that does not require superposition of drivingvoltage and excitation signal was also designed. It reconfigures the conventionalDEA to have separate electrode regions for sensing and actuating. As the DElm deforms under driving voltage, the capacitive change in the electrode regionfor sensing was measured via a capacitor bridge and used as the feedback foractuation control. The self-sensing DEA can, therefore, be implemented with anyhigh voltage power supply. Moreover, the sensing performance is demonstratedto have improved consistency without interference of the electrical field. It alsohas a unique feature of DE lm wrinkling detection.

Differential geometric nonlinear control of a multiple stage evaporator system of the liquor burning facility associated with the Bayer process for alumina production at Alcoa Wagerup alumina refinery, Western Australia was investigated.Mathematical models for differential geometric analysis and nonlinear controller synthesis for the evaporator system were developed. Two models, that were structurally different from each other, were used in the thesis for simulation studies. Geometric nonlinear control structure, consisting of nonlinear state feedback control laws and multi-loop single-input single-output proportional-integral controllers, were designed for the industrial evaporator system. The superiority of the geometric nonlinear control structure for regulatory control of the evaporator system was successfully demonstrated through computer simulations and real-time simulator implementation. The implementation trial has verified the practicality and feasibility of these type of controllers. It also re-solved some practical issues of the geometric nonlinear control structure for industrial control applications. In addition, the implementation trial also established a closer link between the academic nonlinear control theory and the industrial control practices.Geometric nonlinear output feedback controller, consisting of the geometric nonlinear control structure and reduce-order observer was proposed for actual plant implementation on the evaporator system on-site. Its superior performance was verified through computer simulations, but its feasibility on the evaporator system on-site has yet to be investigated either through simulator implementation or actual plant implementation. This investigation was not performed due to the time constraint on the preparation of this thesis and the inavailability of the plant personnel required for this implementation.Robust ++ / nonlinear control structures that are simple and computationally efficient have been proposed for enhancing the performance of geometric nonlinear controllers in the presence of plant/model mismatch and/or external disturbances. The robust nonlinear control structures are based on model error compensation methods. Robustness properties of the proposed robust nonlinear control structures on the evaporator system were investigated through computer simulations and the results indicated improved performance over the implemented geometric nonlinear controller in terms of model uncertainty and disturbance reductions.A software package was developed in MAPLE computing environment for the analysis of nonlinear processes and the design of geometric nonlinear controllers. This developed symbolic package is useful for obtaining fast and exact solutions for the analysis and design of nonlinear control systems. Procedures were also developed to simulate the geometric nonlinear control systems. It was found that MAPLE, while it is superior for the analyses and designs, is not viable for simulations of nonlinear control systems. This was due to limitation of MAPLE on the physical, or virtual, memory management. The use of both symbolic and numeric computation for solutions of nonlinear control system analysis, design and simulation is recommended.To sum up, geometric nonlinear controllers have been designed for an industrial multiple stage evaporator system and their simplicity, practicality, feasibility and superiority for industrial control practices have been demonstrated either through computer simulations or real-time implementation. It is hoped that the insights provided in this thesis will encourage more industry-based projects in nonlinear control, and thereby assist in closing the widening gap between academic nonlinear control theory and industrial control ++ / practice.Keywords: geometric nonlinear control, input-output linearization, multiple stage evaporator, robust geometric nonlinear control, control performance enhancement.

A laboratory experiment and a numerical simulation of a dual well pair SAGD process with live bitumen were conducted to examine operating strategies on the recovery performance of a multiple well pair SAGD process. The experiment was successfully carried out under such operation strategies as injecting steam into one well pair while producing from both producers after chambers mergence to sweep the oil between the two well pairs. The experimental results showed high oil recovery from the transition region between the two well pairs with these operation strategies. Numerical simulation matched reasonably well experimental results, which indicated that the numerical model captured the key mechanisms of the dual well pairs experiment. The improved SAGD process behaviour and performance was demonstrated in terms of faster oil production, enhanced solution gas production, and accelerated adjacent chambers communication in the experimental and numerical studies. These operation strategies could be applied in the multiple well pairs SAGD and enhance SAGD performance after steam chambers merge between adjacent well pairs. / Petroleum Engineering

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Numerous advancements made in the field of computational sciences have made CFD a viable solution to the modern day fluid dynamics problems. Progress in computer performance allows us to solve a complex flow field in practical CPU time. Commodity clusters are also gaining popularity as computational research platform for various CFD communities. This research focuses on evaluating and enhancing the performance of an in-house, unstructured, 3D CFD code on modern commodity clusters. The fundamental idea is to tune the codes to optimize the cache behavior of the node on commodity clusters to achieve enhanced code performance. Accordingly, this work presents discussion of various available techniques for data access optimization and detailed description of those which yielded improved code performance. These techniques were tested on various steady, unsteady, laminar, and turbulent test cases and the results are presented. The critical hardware parameters which influenced the code performance were identified. A detailed study investigating the effect of these parameters on the code performance was conducted and the results are presented. The successful single node improvements were also efficiently tested on parallel platform. The modified version of the code was also ported to different hardware architectures with successful results. Loop blocking is established as a predictor of code performance.