The first coal-fired power plant in Sri Lanka was successfully connected to the national grid in year 2011. The proposal of implementing coal-fired power plants in Sri Lanka has been appearing in power sector master plans since year 1985. It was delayed for many years, mainly due to public protests and indecision of the political leadership of the country. This research analyzes the social and economic barriers faced during the implementation stage. Operation of the plant in terms of system inertia, reliability and stability is discussed. This is the single largest power sector investment in Sri Lanka and returns on the investment were analyzed in this study. As this is the first coal-fired power plant in Sri Lanka, success of this project will create the platform for the public acceptance of future coal-fired power plants. There were some technical failures during the initial years of operation of the plant, and now it records a higher reliability. Furthermore, it is important to summarize the lessons learnt after implementing this project. Future plans of the utility, energy policy of the country and the political agenda of a country should reflect the experience with this project. This is a good example that teaches the lesson; projects which require to be implemented in the national interest should not be postponed or cancelled due to the protest by small groups of people perceived to be affected by the project. It is highlighted that system stability is improved in many cases due to the increase of power system inertia, to which this power plant makes the largest contribution. System inertia is improved in six out of nine scenarios, which were analyzed in this study. Economic benefits gained by the power plant were examined and the study proves that this power plant will have a significant positive effect on the national economy. Loss incurred delaying the project was calculated and it proves the importance of this project.

This study has demonstrated that the phenomenon of acoustic emission can be used to detect and monitor first time deformation characteristics in stiff, heavily-overconsolidated clay soils. The results from two field studies are presented and discussed with the aim of identifying the mechanisms responsible for the generation of acoustic emission. The first study, conducted at the Building Research Establishment's test site at Cowden (Humberside), was a section of cliff, naturally eroded by sea action. The second study, conducted in a 'moth-balled' brick-pit in Arlesey (Bedfordshire), was a large scale test in which instability was induced in a cut slope (in the Gault Clay) by cutting away at the toe. A number of different designs of wave guide were installed at both sites in order to determine the relative performance of each and, also, to provide further insight into the generation mechanisms. Some consideration has also been given to the effect of alternative data processing techniques. The results obtained indicate that the active wave guide model is the more appropriate in explaining the occurrence of acoustic emission and this finding is supported by the results of laboratory tests designed to replicate the perceived role of the wave guide in the field. In itself, identification of the generation mechanism is a result but, more importantly, understanding of the mechanics enables the design of monitoring systems which are suited to particular geotechnical conditions. Some comparison is also made between acoustic emission and standard methods of deformation monitoring. It is observed that acoustic emission can detect and clearly indicate disturbances at the same time as standard methods record such small magnitudes of movement as to be indistinguishable from instrument error. Additionally, a number of triaxial shear tests were conducted on a selection of soils which illustrates that different soils do exhibit different acoustic characteristics. Finally, this study demonstrates the feasibility of envelope processing using analogue to digital signal conversion both in the field and laboratory. Four published papers pertaining to work described within this thesis are appended.

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

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Σε έναν μεγάλο αριθμό βιομηχανικών διεργασιών απαιτείται η διαδικασία της μίξης δύο ή περισσοτέρων υλικών για την παρασκευή του τελικού προιόντος.Ο πιο συνηθισμένος τρόπος μίξης είναι η ανάδευση ενός ή περισσοτέρων υλικών σε μια δεξαμενή. Η δεξαμενή καθώς και ο υπόλοιπος απαραίτητος εξοπλισμός όπως το στροφείο που πραγματοποιεί την ανάδευση, πρέπει να είναι με τέτοιο τρόπο σχεδιασμένος ώστε να είναι σε θέση αφ’ενός να φέρει εις πέρας την διαδικασία της μίξης και την παραγωγή του τελικού αποτελέσματος, τηρώντας κάποιες προδιαγραφές, αφ’εταίρου να είναι μηχανικά ευσταθής και ασφαλής. Λόγω διαφόρων αναγκών κατά την παραγωγική διαδικασία είναι απαραίτητη η αντικατάσταση των σωληνώσεων για την μεταφορά ενός υγρού από μια δεξαμενή επεξεργασίας ή αποθήκευσης σε άλλη, με την χρησιμοποίηση συστημάτων μεταφοράς της δεξαμενής. Άλλοι λόγοι επιβάλλουν την ταυτόχρονη μεταφορά και ανάδευση υλικών σε μια δεξαμενή, ή η δεξαμενή ανάδευσης να είναι στερεωμένη σε μεταλλικά ικριώματα ή να είναι στερεωμένη πάνω σε μεταλλικούς δοκούς. Έτσι, στην περίπτωση του συστήματος μεταφοράς μιας δεξαμενής από ένα σημείο σε κάποιο άλλο πρέπει κανείς να εξετάσει τις διαταραχές που υφίσταται το υγρό που περιέχει η δεξαμενή για παράδειγμα, εξαιτίας της κίνησης της δεξαμενής, για την αποφυγή υπερχείλισης του υγρού. Επιπλέον στην περίπτωση όπου τα υλικά που περιέχει μια δεξαμενή αναδεύονται κατά την μεταφορά της ή αυτή είναι στερεωμένη σε μεταλλικά ικριώματα, πρέπει να εξετάσει κανείς τις επιδράσεις της ανάδευσης στην σταθερότητα της δεξαμενής, και συνεπώς και στο σύστημα στήριξης ή μεταφοράς της ώστε να παρέχεται η αξιοπιστία και η ασφάλεια του συστήματος. Στην παρούσα εργασία χρησιμοποιήθηκε μια δεξαμενή ανάδευσης που περιείχε νερό, και μελετήσαμε τις επιδράσεις που είχε η ανάδευση του νερού, στην ισορροπία της δεξαμενής, καταγράφοντας την κατανομή του βάρους της. Στο πρώτο κεφάλαιο δίνονται διάφοροι ορισμοί και εξισώσεις που περιγράφουν ένα ρευστό και την κίνησή του. Στο δεύτερο κεφάλαιο περιγράφονται οι μονάδες που απαρτίζουν ένα σύστημα ανάδευσης, και στο τρίτο τα αποτελέσματα των φορτίσεων της δεξαμενής κατά την ανάδευσή της, στην πειραματική διάταξη που πραγματοποιήθηκε. / In a large number of industrial processes the mixing of two or more materials is necessary for the production of a final product. The most common form of mixing is the stirring of one or more materials in a mixing tank. The tank as well as the rest of the necessary equipment, for example the impeller which is responsible for the stirring process, must be designed in such a way that it is able to successfully complete the mixing process and produce the final product, according to certain specifications, while keeping mechanical stability and safety. Different needs may arise during the production of a final product. One of these may be the need to replace the pipes which are responsible for transferring one liquid material placed in a tank to another tank, with the use of a transferring system for the tank. Another need may be the simultaneous transfer and stirring of materials in a tank or the stirring tank may need to be stabilized on metal beams. In all these cases, one must evaluate the disturbances and the vibrations which effect the liquid and the tank, in order to ensure the efficiency, stability and safety of the mixing and transfer systems. In the present experimental thesis paper, a stirring tank was used that contained water, and the effects of the stirring of the water on the stability of the tank were studied and analyzed, through the recording of the distribution of the weight during the mixing. The first chapter contains definitions and equations that describe the motion of a fluid. The next chapter describes the parts that comprise a stirring system. Lastly, the third chapter contains the results, the analysis, and the conclusions of the experimental process.

This thesis explored the use of sodium alginate-pectin-poly(ethylene oxide) electrospun fibers as a carrier to stabilize folic acid - an essential micronutrient that is susceptible to degradation when exposed to light and acidic conditions. In the first phase of this research, electrospinning behaviour of aqueous alginate-pectin solutions was investigated. Aqueous polysaccharide solutions could not be electrospun unless poly(ethylene oxide) (PEO) was added (≥20% w/w), resulting in electrospun alginate-pectin fibers that varied from fiber to fiber-bead, depending on the polymer blend ratio, and concentration of the polymer solutions. Polymer solutions properties (surface tension, viscosity, conductivity) were determined to study their effects on the electrospinning behaviour of the polymer solutions. In the second phase of this research, folic acid was incorporated into the polymer solutions and electrospun. The efficacy of these fibers in improving the stability of folic acid under different pH conditions was investigated. FTIR and NMR spectroscopies were employed to elucidate the nature of polymer-polymer and folic acid-polymer interaction. In phase three, the release behaviour of folic acid under simulated gastrointestinal conditions was evaluated. Overall, this research showed that electrospun fibers with different morphologies could be produced by manipulating the polymer concentration, polysaccharide/PEO blend ratio, extent of sonication treatment during sample preparation, and electrospinning process parameters. The positive effect of PEO on the electrospining of alginate-pectin fibers was attributed to its electrical conductivity and surface tension lowering effects on the polymer solutions. Electrospun fibers produced from the combination of alginate-pectin resulted in higher retention of folic acid compared to that of alginate alone. Folic acid encapsulated in crosslinked electrospun fibers achieved close to 100% retention when stored in the dark at pH 3 after 41 days of storage. Minimal release of folic acid from the electrospun fibers was observed at pH 3, although the release was significantly higher at pH 1.2. On the other hand, the release of folic acid was nearly 97% at pH 7.8, a condition that simulated the pH condition in the intestine. From NMR and FTIR data, the stabilization effect of electrospun fibers on folic acid was attributed to physical entrapment and not specific chemical interaction. The research suggests that ethanol-treated crosslinked alginate-pectin electrospun fibers can potentially be used as a folic acid carrier to protect the micronutrient in food products, especially acidic food products such as fruit juices and acidified beverages. / Natural Sciences and Engineering Research Council of Canada (NSERC) and Heinz Company of Canada

Acid treatment, especially at high temperatures, is very challenging since HCl is really corrosive to the metal equipment. The use of HCl is associated with face dissolution, corrosion, and iron precipitation. Organic acids are weak and less corrosive than HCl but they have a limitation, which means that they can't be used at high concentrations. The next option would be chelating agents. Chelating agents are used in well stimulation, iron control during acidizing, and removal of inorganic scales. Chelates such as ethylenediaminetetraacetic acid (EDTA), N-(hydroxyethyl)-ethylenediaminetetraacetic acid (HEDTA), L- glutamic acid-N, N diacetic acid (GLDA), and nitrilotriacetic acid (NTA) are used in high-pressure/high-temperature oil and gas wells. GLDA is environmentally friendly, which makes it favorable. One of the concerns with these chelates is their thermal stability at high temperatures because if they degrade at high temperatures, they may lose their functionality. This study describes the thermal stability of these chelates, thermal degradation products, and some methods to improve their stability. The thermal stability is determined by measuring the concentration before and after heating using a complexo-metric titration utilizing FeCl₃ as a titrant. The degradation products are identified using Mass Spectrometry (MS). A series of experiments were run in the lab at varying temperatures (300 to 400°F) up to 12 hours, and the results shows chelates are not stable at temperatures greater than 350°F. Furthermore, chelates with two nitrogen atoms are more stable than those with one nitrogen atom. Iminodiacetic acid (IDA), acetic acid, and [alpha]-hydroxy acids are the decomposition products. There is a layer of black deposition after the chelates are heated, which is analyzed using Scanning Electron Microscope (SEM). Some coreflood tests are conducted using these degraded chelates to investigate the effect of these solid precipitates on the permeability of carbonate and sandstone cores. Increasing ionic strength and raising pH results in a higher thermal stability. Some salts such as, NH₄Cl, KCl, Csformate, and NaBr are added to chelate solutions to enhance stability.

This thesis studies several issues in the field of macroeconomic and financial stability. In Chapter 2, I argue that systemic bankruptcy of firms can originate from coordination failure in an economy with investment complementarities. I demonstrate that in such an economy, a very small uncertainty about economic fundamentals can be magnified through the uncertainty about the investment decisions of other firms and can lead to coordination failure, which may be manifested as systemic bankruptcy. Moreover, my model reveals that systemic bankruptcy tends to arise when economic fundamentals are in the middle range where coordination matters. High financial leverage of firms greatly increases the severity of systemic bankruptcy. Optimistic beliefs of firms and banks can alleviate coordination failure, but can also increase the severity of systemic bankruptcy once it happens. Chapter 3 studies how coordination failure in a country's new technology investment dampens a country's economic growth. I establish a two-sector Overlapping Generation model where capital goods are produced by two different technologies. The first is a conventional technology with constant returns. The second is a new technology exhibiting increasing returns to scale due to technological externalities, about whose returns economic agents have only incomplete information. My model reveals that coordination failure in new technology investment can lead to slower economic growth. More interestingly, the model generates a positive correlation between economic growth and volatility. In Chapter 4, Frank Milne and I establish a dynamic currency attack model in the presence of a large player. In an attack on a fixed exchange rate regime with a gradually overvalued currency, both the inability of speculators to synchronize their attack and their incentive to time the collapse of the regime lead to the persistent overvaluation of the currency. We find that the presence of a large player can accelerate or delay the collapse of the regime, depending on his incentives to preempt other speculators or to ``ride the overvaluation." / Thesis (Ph.D, Economics) -- Queen's University, 2007-11-28 15:26:27.834

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