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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

The development of computational high-throughput approaches for screening metal-organic frameworks in adsorptive separation applications

Tao, Andi January 2019 (has links)
Chemical separation undoubtedly accounts for a large proportion of process industries' activities. In the past few decades, 10-15% of the world's energy consumed was resulted from separation process. Tremendous efforts have been made in separating the components of large quantities of chemical mixtures into pure or purer forms in most industrial chemists. In addition, industrial development and population growth would lead to a further increase in the global demand for energy in the future. This makes the effective and efficient energy separation process one of the most challenging tasks in engineering. Adsorptive separation using porous materials is widely used in industry today. In order for an adsorptive separation process to be efficient, the essential requirement is a selective adsorbent that possesses high surface area and preferentially adsorbs one component (or class of similar components). Metal-organic frameworks (MOFs) are promising materials for separation purposes as their diversity, due to their building block synthesis from metal clusters and organic linker, gives rise to a wide range of porous structures. Engineering of a separation process is a multi-disciplinary problem that requires a holistic approach. In particular, material selection for industrial applications in the field of MOFs is one of the most significant engineering challenges. The complexity of a screening exercise for adsorptive separations arises from the multitude of existing porous adsorbents including MOFs. There are more than 80,000 structures that have been synthesised so far, as well as the multivariate nature of that performance criteria that need to be considered when selecting or designing an optimal adsorbent for a separation process. However, it is infeasible to assess all the potential materials experimentally to identify the promising structure for a particular application. Recently, molecular simulation and mathematical modelling have seen an ever- growing contribution to the research field of MOFs. The development of these computational tools offers a unique platform for the characterisation, prediction and understanding of MOFs, complementary to experimental techniques. In the first part of this research, Monte Carlo molecular simulation and a number of advanced mathematical methods were used to investigate newly synthesised or not well-known MOFs. These computational techniques allowed not only to characterise materials with their textural properties, but also to predict and understand adsorption performances at the atomic level. Based on the insight gained from the molecular simulation, two computational high-throughput screening approaches were designed and assessed. A multi-scale approach has been proposed and used which combined high-throughput molecular simulation, data mining and advanced visualisation, process system modelling and experimental synthesis and testing. The focus here was on two main applications. On one hand, the challenging CO/N2 separation, which is critical for the petrochemical sector, where two molecules have very similar physical properties. On the other hand, the separation of chiral molecules. For CO/N2 separation, a database of 184 Cu- Cu paddle-wheels MOFs, which contains unsaturated metal centres as strong interaction sites, was extracted from CSD (Cambridge Structural Database) MOF subset for material screening. In the case of chiral separation, an efficient high-throughput approach based on calculation of Henry's constant was developed in this research. Owning to the nature of chirality, this separation of relevance to the pharmaceutical sector is crucially important. A database of 1407 homochiral MOFs was extracted, again, from CSD MOF subset for material screening of enantioselective adsorption. The results obtained in these computational high-throughput approaches allows the screening of interesting, existing structures, and would have a huge impact on making MOFs to be industrially interesting adsorbents as well as guiding the synthesis of these materials. From the many different possibilities, the ultimate interest of this work is in developing an integrated systematic study of the structure-adsorption performance relationship working with a limited library of candidate MOF structures in order to identify promising trends and materials for the specific applications mentioned above. In summary, the overall aim of this research was exploiting different computational techniques, developing novel high-throughput approaches in order to tackle important engineering challenges.
22

Virtual screening and bioactivities of small molecules

Koutsoukas, Alexios January 2014 (has links)
No description available.
23

Novel screening methods for inhibitors of the human ubiquitin-conjugating enzymes

Koszela, Joanna January 2014 (has links)
The ubiquitin-proteasome system (UPS) controls the stability, activity and localisation of most of the proteome and regulates virtually all cellular processes through modification of proteins with ubiquitin. Ubiquitin conjugation is mediated by a conserved enzymatic cascade composed of E1, E2 and E3 enzymes, which cooperate to activate and transfer ubiquitin to substrate proteins. Dysfunction of the UPS is implicated in many disease states, including cancer, neurodegeneration, immune and cardiovascular disorders. Despite the central role of the UPS in cellular regulation, our understanding of the function, interactions and specificity of proteins that comprise the UPS is still limited. One approach to dissect and to study the UPS is to identify molecular probes, which can be used to specifically interrogate catalytic mechanisms and can be potentially considered as entry points for drug discovery. This work focuses on developing novel high-throughput screening methods for inhibitors of the ubiquitin-conjugating enzymes (E2s), using a unicellular organism Saccharomyces cerevisiae and in vitro technologies. S. cerevisiae is a model organism, commonly used in research as a valuable tool for genetic investigations and other high-throughput studies. In this work, we evaluated the toxicity of exogenously expressed human E2s on yeast cells and discovered that one of the E2s, Ube2U, significantly inhibited yeast growth. This inhibition was dependent on the Ube2U ubiquitin-conjugation activity, as demonstrated with a catalytically inactive Ube2U C89A control, which did not affect yeast growth. The growth defect induced by Ube2U allowed us to develop a screening setup for inhibitors of Ube2U, where the enzyme activity was coupled to cell growth readout. Potential Ube2U inhibitors would be identified as rescuers of the slow growing Ube2U-expressing yeast phenotype. Although screening methods in yeast are relatively straightforward to set up and run, the advantages of this system, namely simplicity of the detection signal and high-throughput, are limited by the fact that yeast is not a recognised large scale screening system in pharmaceutical industry, and that it is difficult to identify the target in a complex pathway such as the UPS. In vitro technologies are needed to provide the necessary structure-activity relationship for chemical optimisation. Therefore, we developed a novel, fluorescence-based, miniaturised assay technology, suitable for biochemical investigations and screening for inhibitors of a wide range of specific ubiquitination reactions within the UPS.
24

Measuring Highway Work Zone Throughput

Hicks, Carolyn 10 August 2009 (has links)
The focus of this project is highway construction zones and the impact of lane closures on traffic. By measuring throughput (the number of vehicles that can flow through a work zone in a given amount of time), analysis was performed to determine the factors that affect this value. Successful data collection uncovered a paradox. Often work zones would see no queuing, indicating the lane could have been closed for longer hours. Alternatively sites with forced flow allowed fewer vehicles through the site than expected, indicating that the design value is too high, requiring shorter lane closure hours. A generic model for throughput was developed as well as a better functioning highway specific model. In addition to these models, this project developed a spreadsheet-based form of analysis named SZUDA (Simplified work Zone User Delay Analysis) that determines queue length and approximate costs associated with road user delay.
25

Measuring Highway Work Zone Throughput

Hicks, Carolyn 10 August 2009 (has links)
The focus of this project is highway construction zones and the impact of lane closures on traffic. By measuring throughput (the number of vehicles that can flow through a work zone in a given amount of time), analysis was performed to determine the factors that affect this value. Successful data collection uncovered a paradox. Often work zones would see no queuing, indicating the lane could have been closed for longer hours. Alternatively sites with forced flow allowed fewer vehicles through the site than expected, indicating that the design value is too high, requiring shorter lane closure hours. A generic model for throughput was developed as well as a better functioning highway specific model. In addition to these models, this project developed a spreadsheet-based form of analysis named SZUDA (Simplified work Zone User Delay Analysis) that determines queue length and approximate costs associated with road user delay.
26

Measuring Work Zone Throughput and User Delays

Mushtaq, Mohammad 17 February 2011 (has links)
A larger amount of funding and attention are going toward highway infrastructure of Ontario for rehabilitation, maintenance and construction projects. These rehabilitation and maintenance activities on highways involve lane closures, which reduce the traffic throughput and cause delays for the road users. The impact of these activities is very important and has led to research into improvements of work zones in Ontario. To prevent the significant cost that these construction delays have on the general public, contractors are required to keep highway lanes open during the peak traffic hours and work at night. However, working at night may reduce the quality of the work by increasing cold joints and construction joints in the pavement, and may increase the amount of time needed to complete the work. Therefore, finding a balance between the times that the lanes can be closed and the times they should be kept open requires an accurate prediction of the construction work zone throughputs, which can increase the efficiency of the contractor work, save money and reduce the user delay costs. Consequently, this study which has been funded by the Ministry of Transportation of Ontario (MTO) Highway Infrastructure Innovation Funding Program (HIIFP) involves measurement of highway construction work zones throughput of Southern Ontario, to determine the factors affecting the throughput. It has been carried out in partnership with researchers at the University of Toronto. For this study, a manual counting method for collecting throughput data has been employed. This involved data collection of variables such as heavy vehicles which had not been included in previous studies. This provides the visual confirmation of queuing and assists in evaluating the intensity of work activity at the work zones. New generic models for throughput have been developed in this research to better describe current state-of-the practice on Southern Ontario highways. Furthermore, a better functioning highway specific model was developed to calculate the throughput of the MTO Southern Ontario Highway network. In addition to development of these new models, this project involved further development and refinement to a spreadsheet based model SZUDA (Simplified work Zone User Delay Analysis) that uses normal hourly traffic flows to calculate the resulting queue for that entire hour and approximate user delay cost associated with road user delay. Overall, the thesis describes a methodology for collection of data in work zones. This involved collection of data during 2009 and 2010 Ontario construction season. Furthermore, the data were then used to develop more reliable generic and highway specific models for the MTO. These models can be used to determine when and how work zones should be established. Finally the refined SZUDA model and case studies demonstrate the impact of various work zone configurations on the traveling public.
27

An Efficient Packet Forwarding Mechanism Based on Bandwidth Prediction with Consideration of V2V and V2I Environment

Jhuang, Ya-Lin 09 August 2011 (has links)
none
28

Throughput Analysis and Enhancement of Multi-Channel MAC Protocol in Ad-Hoc Networks

Kao, Hui-hsiang 07 September 2006 (has links)
Multi-channel MAC protocol is that schedules frames to be exchanged on different channels. To analyze the performance of multi-channel MAC protocol, an analytical model is proposed to compute the network throughput. Simulation results show that the proposed model is able to model the behaviors of multi-channel MAC protocol accurately. Furthermore, based on the analysis model, in this thesis we also proposes an adaptive contention window scheme to enhance the network throughput by tuning the initial contention window size. Results indicate that the proposed scheme can reduce the cost of collisions and increase the network throughput.
29

On improving performance and conserving power in cluster-based web servers

Vageesan, Gopinath 25 April 2007 (has links)
Efficiency and power conservation are critical issues in the design of cluster systems because these two parameters have direct implications on the user experience and the global need to conserve power. Widely adopted, distributor-based systems forward client requests to a balanced set of waiting servers in complete transparency to the clients. The policy employed in forwarding requests from the front-end distributor to the backend servers plays an important role in the overall system performance. Existing research separately addresses server performance and power conservation. The locality-aware request distribution (LARD) scheme improves the system response time by having the requests served by web servers which have the data in their cache. The power-aware request distribution aims at reducing the power consumption by turning the web servers OFF and ON according to the load. This research tries to achieve power conservation while preserving the performance of the system. First, we prove that using both power-aware and locality-aware request distribution together provides optimum power conservation, while still maintaining the required QoS of the system. We apply the usage of pinned memory in the backend servers to boost performance along with a request distributor design based on power and locality considerations. Secondly, we employ an intelligent-proactive-distribution policy at the front-end to improve the distribution scheme and complementary pre-fetching at the backend server nodes. The proactive distribution depends on both online and offline analysis of the website log files, which capture user navigation patterns on the website. The prefetching scheme pre-fetches the web pages into the memory based on a confidence value of the web page predicted by backend using the log file analysis. Designed to work with the prevailing web technologies, such as HTTP 1.1, our scheme provides reduced response time to the clients and improved power conservation at the backend server cluster. Simulations carried out with traces derived from the log files of real web servers witness performance boost of 15-45% and 10-40% power conservation in comparison to the existing distribution policies.
30

Cryptoraptor : high throughput reconfigurable cryptographic processor for symmetric key encryption and cryptographic hash functions

Sayilar, Gokhan 03 February 2015 (has links)
In cryptographic processor design, the selection of functional primitives and connection structures between these primitives are extremely crucial to maximize throughput and flexibility. Hence, detailed analysis on the specifications and requirements of existing crypto-systems plays a crucial role in cryptographic processor design. This thesis provides the most comprehensive literature review that we are aware of on the widest range of existing cryptographic algorithms, their specifications, requirements, and hardware structures. In the light of this analysis, it also describes a high performance, low power, and highly flexible cryptographic processor, Cryptoraptor, that is designed to support both today's and tomorrow's encryption standards. To the best of our knowledge, the proposed cryptographic processor supports the widest range of cryptographic algorithms compared to other solutions in the literature and is the only crypto-specific processor targeting the future standards as well. Unlike previous work, we aim for maximum throughput for all known encryption standards, and to support future standards as well. Our 1GHz design achieves a peak throughput of 128Gbps for AES-128 which is competitive with ASIC designs and has 25X and 160X higher throughput per area than CPU and GPU solutions, respectively. / text

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