The investigations of the methods for the reduction of chloropyrimidines

This thesis investigated on the dehalogenation of 2, 4- dichloropyrimidine in various different conditions. These conditions were changed by varying the solvents, the amount of catalysts and the hydrogen chloride acceptors in order to study the effects on the yields. It was found that the ether-aqueous sodium hydroxide medium with palladium on charcoal as the catalysts gave the best yield at the proper time of the reaction only when the ether: water ratio of 5:1. The ethanol was found as the side product during the reduction. The isolation problem of pyrimidine from the reaction mixture was studied and some organic compounds have been used as the "chaser" in the fractional distillation using Podbielniak column. Quinoline, naphthalene, and N, N-dimethylaniline were found to be the effective ones, but o-xylene and mesitylene formed the azeotropic mixture with pyrimidine. The compositions of pyrimidine fractions were identified by the method of gas chromatography analysis

A Bayesian method for material identification of composite plates via dispersion curves

Ultrasonic guided waves offer a convenient and practical approach to structural health monitoring and non-destructive evaluation. A key property of guided waves is the fully defined relationship between central frequency and propagation characteristics (phase velocity, group velocity and wavenumber)—which is described using dispersion curves. For many guided wave-based strategies, accurate dispersion curve information is invaluable, such as group velocity for localisation. From experimental observations of dispersion curves, a system identification procedure can be used to determine the governing material properties. As well as returning an estimated value, it is useful to determine the distribution of these properties based on measured data. A method of simulating samples from these distributions is to use the iterative Markov-Chain Monte Carlo (MCMC) procedure, which allows for freedom in the shape of the posterior. In this work, a scanning-laser Doppler vibrometer is used to record the propagation of Lamb waves in a unidirectional-glass-fibre composite plate, and dispersion curve data for various propagation angles are extracted. Using these measured dispersion curve data, the MCMC sampling procedure is performed to provide a Bayesian approach to determining the dispersion curve information for an arbitrary plate. The distribution of the material properties at each angle is discussed, including the inferred confidence in the predicted parameters. The percentage errors of the estimated values for the parameters were 10–15 points larger when using the most likely estimates, as opposed to calculating from the posterior distributions, highlighting the advantages of using a probabilistic approach

Feasibility study on a full‐scale wind turbine blade monitoring campaign: Comparing performance and robustness of features extracted from medium‐frequency active vibrations

The present work investigates the performance of different features, extracted from vibration-based data, for structural health monitoring of a 52-meter wind turbine blade during fatigue testing. An active vibration monitoring system was used during the test campaign, providing periodic excitation of single frequencies in the medium-frequency range, and using accelerometers to measure the vibration output on different parts of the blade. Based on previous work from the authors, data is available for the wind turbine blade in healthy state, with a manually induced damage, and with progressively increasing damage severity. Using the vibration data, different signal processing methods are used to extract damage-sensitive features. Time series methods and time-frequency domain methods are used to quantify the applied active vibration signal. Using outlier analysis, the health state of the blade is classified, and the classification accuracy through use of the different features is compared. Highest performance is generally obtained by auto-regressive modeling of the vibration outputs, using the auto-regressive parameters as features. Finally, suggestions for future improvements of the present method toward practical implementation are given

A full-scale wind turbine blade monitoring campaign: detection of damage initiation and progression using medium-frequency active vibrations

This work is concerned with a structural health monitoring campaign of a 52-m wind turbine blade. Multiple artificial damages are introduced in the blade sequentially, and fatigue testing is conducted with each damage in sequence. Progressive fatigue-driven damage propagation is achieved, enabling investigations concerning detection of initiation and propagation of damage in the blade. Using distributed accelerometers, operational modal analysis is performed to extract the lower-order natural vibration modes of the blade, which are shown to not be sensitive to small damages in the blade. To enable monitoring of small damages, an active vibration monitoring system is used, comprised of an electrodynamic vibration shaker and distributed accelerometers. From the accelerometer data, frequency domain methods are used to extract features. Using the extracted features, outlier detection is performed to investigate changes in the measurements resulting from the introduced damages. Capabilities of using features based on the active vibration data for detection of initiation and progression of damage in a wind turbine blade during fatigue testing are investigated, showing good correlation between the observed damage progression and the calculated changes in the damage index

A Bayesian method for material identification of composite plates via dispersion curves

Ultrasonic guided waves offer a convenient and practical approach to structural health monitoring and non-destructive evaluation. A key property of guided waves is the fully-defined relationship between central frequency and propagation characteristics (phase velocity, group velocity and wavenumber) -- which is described using dispersion curves. For many guided wave-based strategies, accurate dispersion curve information is invaluable, such as group velocity for localisation. From experimental observations of dispersion curves, a system identification procedure can be used to determine the governing material properties. As well as returning an estimated value, it is useful to determine the distribution of these properties based on measured data. A method of simulating samples from these distributions is to use the iterative Markov-Chain Monte Carlo procedure, which allows for freedom in the shape of the posterior. In this work, a scanning-laser doppler vibrometer is used to record the propagation of Lamb waves in a unidirectional-glass-fibre composite plate, and dispersion curve data for various propagation angles are extracted. Using these measured dispersion curve data, the MCMC sampling procedure is performed to provide a Bayesian approach to determining the dispersion curve information for an arbitrary plate

Lithium-ion battery separator membranes based on poly(L-lactic acid) biopolymer

Sustainable materials are increasingly needed in lithium ion batteries in order to reduce their environmental impact and improve their recyclability. This work reports on the production of separators using poly (L-lactic acid) (PLLA) for lithium ion battery applications. PLLA separators were obtained by solvent casting technique, by varying polymer concentration in solution between 8 wt.% and 12 wt.% in order to evaluate their morphology, thermal, electrical and electrochemical properties. It is verified that morphology and porosity can be tuned by varying polymer concentration and that the separators are thermally stable up to 250 ºC. The best ionic conductivity of 1.6 mS/cm was obtained for the PLLA separator prepared from 10 wt.% polymer concentration in solution, due to the synergistic effect of the morphology and electrolyte uptake. For this membrane, a high discharge capacity value of 93 mAh.g-1 was obtained at the rate of 1C. In this work, it is demonstrated that PLLA is a good candidate for the development of separator membranes, in order to produce greener and environmentally friendly batteries in a circular economy context.Work supported by the Portuguese Foundation for Science and Technology (FCT) undes strategic funding UID/FIS/04650/2020 and UID/QUI/0686/2020, project PTDC/FISMAC/28157/2017, and Grants SFRH/BD/140842/2018 (J.C.B.), SFRH/BPD/121526/2016 (D.M.C), CEECIND/00833/2017 (R.G.) and SFRH/BPD/112547/2015 (C.M.C.). Financial support from the Basque Government Industry Department under the ELKARTEK and HAZITEK programs is also acknowledged. Technical and human support provided by SGIker (UPV/EHU, MICINN, GV/EJ, EGEF and ESF) is gratefully acknowledge

Economic policy and development in South-East Asian Economies

The importance of South-east Asian economies in the world economy became apparent through their rapid increasing shares in the world trade. The fast growing trade sector in these countries enabled a near double digit economic growth rate in the 1970s and 1980s. When a group of under-developed economies quickly turns themselves into emerging economies and gain a reputation as an 'Asian Miracle', this naturally attracts economists' attention into the field. The key driving force of the growth rate in these countries was seen to be exports and investment, this has been emphasized and accepted in a large number of papers.However, an equally interesting question concerns the relative growth rates of economies within the region, an issue which the first paper, Comparative Economic Development, of this thesis will investigate. Korea, Thailand and the Philippines were at a similar state of development with comparable level of GNP per capita in 1960, but had achieved very different levels of economic success by 1990. Ironically, among the three countries in consideration, the Philippines was endowed with the most favourable human and capital resources but turned out to be the least successful economy 30 years afterward, and the opposite is true for Korea. Although regression results confirm that their growth rates have been influenced by common factors such as exports and investment, their relative success can partially be explained by differences in other factors captured in the model. To what extent do these other factors play a role in explaining their relative growth rate during 1960-1990? Were they country-specific factors - or can they be duplicated in other countries? The first paper attempts to provide insights to these questions and to identify the key ingredients of economic success.Regardless of relative economic success found within the region, these South-east Asian countries have recorded the highest average growth rates among developing countries. However, this reputation was shattered when the financial crisis broke out in one of the fast growing economies in the region, Thailand. This crisis was largely unanticipated in terms of its timing and severity and economists are still to agree on its root causes. The second paper tries to identify the cause of the crisis by examining what actually happened during the few years preceding the crisis in the original country where the crisis broke out.</p

Economic policy and development in south-east Asian economies

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