Final Report for National Science Foundation Divisions of Policy Research and Analysis and International Programs - Grant No. PRA-8007498 and Consejo Nacional de Ciencia y Tecnologia Comision Nacional de Zonas Aridas

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As the current rate of improvement in processor performance far exceeds the rate of memory performance, memory latency is the dominant overhead in many performance critical applications. In many cases, automatic compiler-based approaches to improving memory performance are limited and programmers frequently resort to manual optimisation techniques. However, this process is tedious and time-consuming. Furthermore, a diverse range of a rapidly evolving hardware makes the optimisation process even more complex. It is often hard to predict the potential benefits from different optimisations and there are no simple criteria to stop optimisations i.e. when optimal memory performance has been achieved or sufficiently approached. This thesis presents a platform independent optimisation approach for numerical applications based on iterative feedback-directed program restructuring using a new reasonably fast and accurate performance prediction technique for guiding optimisations. New strategies for searching the optimisation space, by means of profiling to find the best possible program variant, have been developed. These strategies have been evaluated using a range of kernels and programs on different platforms and operating systems. A significant performance improvement has been achieved using new approaches when compared to the state-of-the-art native static and platform-specific feedback directed compilers.

Advancement in information technology has influenced various aspects of human lives. The penetration of information technology is likely to increase in future. Therefore, it is imperative that one should be aware of the factors, which encourage or discourage customers towards use of information technology and related products and services. With reference to e-commerce, organizations should analyze preferences of consumers in mobile-commerce environment and based on their findings, should adjust their product or service accordingly. The current research was based on the future research areas highlighted by Pantano and Priporas (2016) and covered the limitations of their study using a larger sample (150 customers) using the context of Pakistan. Shahid et al. (2015) Highlighted that mobile-phone industry of Pakistan is one of the vibrant industries of the world. The mobile-density of Pakistan is one of the highest of Asia. The findings of this research revealed different dimensions of independent variables. For perceived ease of use, these dimensions were understandable and easier for one to become skillful in using MBA. Likewise, for perceived usefulness, these dimensions were opportunity of processing more banking transactions and always available. Further to this, for innovativeness of user, these dimensions were being an unconventional person, prefer to experiment new things in life and prefer to obtain information about new products. Likewise, for design of application, these dimensions were using MBA is secure, using MBA has a pleasant experience on my mood, easier to navigate MBA, can customize MBA according to my needs and MBA gives me an opportunity to compare charges with competitors. Finally, for finance cost these dimensions were using MBA saves transportation cost, to and from stores and using MBA saves time of visiting Bank. In addition, this study helped in identification of relative importance of different independent variables on the dependent variables. It was revealed that perceived usefulness is the most influential factor which influences future usage intentions of the people whereas design of application is least influential factor. Likewise, finance cost and innovativeness of users are also important factors. It was suggested that MBA providers should focus on female segments as well, create awareness of MBA among older people, provide MBA in native language, and focus on promoting MBA using different dimensions such as perceived usefulness and cost efficiency. Moreover, this research contributed to previous research in various forms including identification of important dimensions of select variables as well as relative importance of perceived ease of use, perceived usefulness, innovativeness, design of application and cost. Researcher identified various research limitations. Future researchers should overcome these limitations.

Two important trends in computer systems are that applications are moved to the Internet as web applications, and that computer systems are getting an increasing number of cores to increase the performance. It has been shown that JavaScript in web applications has a large potential for parallel execution despite the fact that JavaScript is a sequential language. In this thesis, we show that JavaScript execution in web applications and in benchmarks are fundamentally different and that an effect of this is that Just-in-time compilation does often not improve the execution time, but rather increases the execution time for JavaScript in web applications. Since there is a significant potential for parallel computation in JavaScript for web applications, we show that Thread-Level Speculation can be used to take advantage of this in a manner completely transparent to the programmer. The Thread-Level Speculation technique is very suitable for improving the performance of JavaScript execution in web applications; however we observe that the memory overhead can be substantial. Therefore, we propose several techniques for adaptive speculation as well as for memory reduction. In the last part of this thesis we show that Just-in-time compilation and Thread-Level Speculation are complementary techniques. The execution characteristics of JavaScript in web applications are very suitable for combining Just-in-time compilation and Thread-Level Speculation. Finally, we show that Thread-Level Speculation and Just-in-time compilation can be combined to reduce power usage on embedded devices.

Surface topography is known to be important in biomedical applications such as scaffolds for tissue regeneration and has been shown to affect wettability and cell behaviour. Traditionally, topographical effects such as surface texturing have been generated using methods such as photolithography, soft lithography, thermal embossing, and laser/electron beam techniques. This thesis introduces a relatively new technique known as photoembossing to create surface texturing for biomedical applications. Photoembossing is used to produce surface texturing on polymer surfaces by patterned ultraviolet (UV) exposure of a photopolymer blend without an etching step or an expensive mould. After a short general introduction and a literature review, the first experimental chapters describe surface patterning of poly(methyl methacrylate) (PMMA) photopolymer substrates by photoembossing. PMMA is blended with an acrylate monomer and photoinitiator by dissolution in a volatile solvent and processed into films by wire bar coating, and fibres are produced by electrospinning. Surface texture is achieved on both films and fibres by photoembossing. Endothelial cell culture shows that the substrates are biocompatible and cells readily adhere to the surface. In tissue regeneration applications, scaffold degradation is often important to allow tissue in-growth. Thus, in subsequent studies polylactide-co-glycolide (PLGA) is used as a polymer binder. PLGA blended with a triacrylate monomer showed partial degradation after 10 weeks, with a cross-linked acrylate network remaining. Endothelial cell adhesion was even better on the PLGA photopolymer substrates compared to PMMA. Furthermore, surface texture improved cell adhesion and proliferation on the PLGA photopolymer. To obtain completely degradable substrates, thiol monomer was used in addition to the acrylate to produce ester bonds after the thiol-ene reaction, which is cleavable by hydrolysis. Accelerated degradation in sodium hydroxide (NaOH) showed complete degradation of this photopolymer system. The degradation rate of the photopolymer could be tuned by the molecular weight of the acrylate monomer, with low molecular weight monomers degrading more slowly than high molecular weight species. Furthermore, the height of the surface relief structures could be enhanced by using low-molecular-weight acrylate monomers. Endothelial cell culture revealed biocompatibility of the blend and cells were able to adhere after 24 hours of seeding. This thesis demonstrates that photoembossing is a viable technique in producing surface texture for tissue engineering applications. This surface texture can be achieved on both biocompatible and biodegradable photopolymer films and fibres.

Drones can be used for several civil applications including search and rescue, coverage, and aerial imaging. Newer applications like construction and delivery of goods are also emerging. Performing tasks as a team of drones is often beneficial but requires coordination through communication. In this thesis, the communication requirements of video streaming drone applications based on existing works are studied. The existing communication technologies are then analyzed to understand if the communication requirements posed by these drone applications can be met by the available technologies. The shortcomings of existing technologies with respect to drone applications are identified and potential requirements for future technologies are suggested. The existing communication and routing protocols including ad-hoc on-demand distance vector (AODV), location-aided routing (LAR), and greedy perimeter stateless routing (GPSR) protocols are studied to identify their limitations in context to the drone networks. An application scenario where a team of drones covers multiple areas of interest is considered, where the drones follow known trajectories and transmit continuous streams of sensed traffic (images or video) to a ground station. A route switching (RS) algorithm is proposed that utilizes both the location and the trajectory information of the drones to schedule and update routes to overcome route discovery and route error overhead. Simulation results show that the RS scheme outperforms LAR and AODV by achieving higher network performance in terms of throughput and delay. Video streaming drone applications such as search and rescue, surveillance, and disaster management, benefit from multicast wireless video streaming to transmit identical data to multiple users. Video multicast streaming using IEEE 802.11 poses challenges of reliability, performance, and fairness under tight delay bounds. Because of the mobility of the video sources and the high data-rate of the videos, the transmission rate should be adapted based on receivers' link conditions. Rate-adaptive video multicast streaming in IEEE 802.11 requires wireless link estimation as well as frequent feedback from multiple receivers. A contribution to this thesis is an application-layer rate-adaptive video multicast streaming framework using an 802.11 ad-hoc network that is applicable when both the sender and the receiver nodes are mobile. The receiver nodes of a multicast group are assigned with roles dynamically based on their link conditions. An application layer video multicast gateway (ALVM-GW) adapts the transmission rate and the video encoding rate based on the received feedback. Role switching between multiple receiver nodes (designated nodes) cater for mobility and rate adaptation addresses the challenges of performance and fairness. The reliability challenge is addressed through re-transmission of lost packets while delays under given bounds are achieved through video encoding rate adaptation. Emulation and experimental results show that the proposed approach outperforms legacy multicast in terms of packet loss and video quality.

Due to their unique structure and flexible choice of materials, electrospun degradable and biocompatible polymer fibres are considered to be extremely suitable for biomedical applications such as tissue engineering and drug delivery, either on their own or integrated within composites. Conventional electrospun fibre composites are typically based on non-woven mats and therefore limited to simple-curved geometries (films, membranes, etc.). For aqueous composites such as hydrogels, the hydrophobicity of the materials sometimes prohibits fibres to be easily integrated or distributed in these composites. In this thesis, a review on the topic is firstly presented in Chapter 2, introducing and discussing engineering of electrospun fibre as well as their biomedical applications. In Chapter 3, electrospun polylactide (PLA) fibres reinforced poly(trimethylene carbonate) (PTMC) composites are prepared. The composites are loaded with both continuous and short PLA fibres, achieving significant mechanical enhancement and offering opportunities to produce composites conveniently using liquid formulations. Chapter 4 presents the development of shape memory polymer composites based on a combination of PLA fibres and a PTMC matrix. By loading different amounts of short fibres with different aspect ratios or by using plasticisers, the shape memory behaviour is modulated; and composites of more complex geometries are produced. In Chapter 5, PTMC-PLA fibre composites are made into drug release system. Dexamethasone-loaded PLA fibres are integrated into a PTMC matrix, showing sustained drug release and stimulating stem cell osteogenic differentiation. This concept gives promise to loading various drugs into photo-crosslinked structures without denaturation. In Chapter 6, electrospun PLA fibres are functionalized by amphiphilic block copolymer polylactide-block-poly[2-(dimethylamino)ethyl methacrylate] (PLA-b-PDMAEMA) for the development of carboxymethylcellulose composites hydrogels. Functionalization of PLA fibres not only allows for easy integration and dispersion into the hydrogel, but also enhances the interfacial bonding between fibre and hydrogel. In the last chapter (Chapter 7), some conclusions are drawn and future works are discussed.

Filmes de óxidos de molibdênio, com ou sem a inclusão de metais, foram eletroquimicamente depositados sobre eletrodos de carbono vítreo em solução de Mo(VI) com pH ajustado em 2,5 ou 3,0. Estes filmes foram caracterizados por Soft X-ray Spectroscopy (SXS), X-ray Diffraction (XRD) e Rutherford Backscattering Spectroscopy (RBS). A coordenação local dos sítios de Mo foram analizadas. As configurações estruturais locais do Mo foram avaliadas quando diferentes números de ciclos de potencial foram empregados na modificação dá superfície do eletrodo. Alguns metais (Pt, Pd, Rh e Cu) foram codepositados com as espécies de Mo e seu efeito nos materiais obtidos foi investigado. O grau de ocupação do orbital 4d do Mo foi examinado como um indicador da existência de interações entre o Mo e o metal codepositado. A incorporação de Pt no filme de óxidos na superfície de um eletrodo de ouro foi caracterizada por espectroscopia PIXE. O eletrodo modificado por óxidos de molibdênio foi estudado em faixas de potencial positivas frente à oxidação de nitrito (NO2-) e de óxido nítrico (NO). A relação entre a porosidade do filme e a presença de água em seus interstícios foi examinada e a capacidade de retenção de NO e NO2 foi também investigada. O eletrodo modificado foi usado como um sensor amperométrico em um sistema de injeção em fluxo (FIA) e o método foi empregado na determinação de nitrito em amostras de lingüiça. A oxidação de H2O2 foi investigada em superfície recoberta por filme de óxidos de Mo com Pt codepositada. O efeito do pH, do potencial e do tempo de pré-redução do filme de Pt e MoOx foi discutida. O comportamento eletroquímico dos filmes codepositados de Rh, Pd, Pt ou Cu e MoOx foi caracterizados comparativamente pela redução do iodato e pela oxidação do nitrito e do etanol nestes substratos. H4MogO26 foi empregado para preparar filmes contendo molibdênio e sua resposta eletroquímica foi comparada com as obtidas com o filme depositado por procedimento usual. O filme de óxidos de molibdênio foi usado com sucesso na imobilização de um complexos de Ru(III) na superfície de carbono vítreo. / Molybdenum oxide films with and without metal inclusion were electrochemically deposited on glassy carbon electrodes from Mo(VI) solutions at pH 2.5 or pH 3.0. These films were characterized by Soft X-ray Spectroscopy (SXS), X-ray Diffraction (XRD) and Rutherford Backscattering Spectroscopy (RBS). The local coordination of Mo sites was analyzed. The Mo local structure configurations were evaluated when different number of potential cycles were employed in the modification of the electrode surface. Some metaIs (Pt, Pd, Rh and Cu) were codeposited with the Mo species and their effect on the obtained material was investigated. The occupancy leveI of the 4d orbital of Mo was examined as an indicator of interactions between Mo and codeposited metals. The incorporation of Pt in the oxide film at a gold electrode surface was characterized by PlXE spectroscopy. The electrode modified by molybdenum oxides was studied at positive potential ranges for the oxidation of nitrite (NO2-) and nitric oxide (NO). The relationship between the porosity of the film and its water content was exarnined and the entrapment of NO and NO2 was also investigated. The modified electrode was used as an amperometric sensor in a flow injection configuration and the method was employed in the deterrnination of nitrite in sausage samples. The oxidation of H2O2 was investigated at surfaces covered by the Mo filrn with codeposited Pt. The effect of pH and potential and time of pre-reduction on the response of the film with Pt was discussed. The electrochemical behaviour of codeposited films of Rh, Pd, Pt or Cu and Mo MoOx was characterized comparatively for the reduction of iodate and the oxidation of nitrite and ethanol. 4MogO26 was also employed to prepare films containing molybdenum and their electrochemical responses were compared with those obtained by using the film electrodeposited by the usual procedure. The molybdenum oxide film was successfully used for the immobilization of Ru(III) complex at glassy carbon surfaces.

Qin Shuijie. / "August 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 109-123). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.