Dynamics and Performance of Tethered Airborne Wind Energy Systems

This research work presents the dynamics and performance of tethered airborne wind energy systems. To this end, aerodynamic theories for crosswind kite power systems (CKPSs) and an aerostatic power system (APS) have been developed along with the tether models for the respective systems. Two semi-analytical aerodynamic models based on the blade element momentum (BEM) theory considering the effects of induction factor, reel-out ratio, solidity factor, rotor incidence angle, side slip and tether drag are developed for CKPSs. Aerodynamic model 1 is for lift mode CKPSs while Aerodynamic model 2 is for lift mode or drag mode CKPSs or a combination of both. Verification and parametric studies proved the accuracy of the models and gave insights into the combined effects of the operational and geometric parameters. In addition, a semi-analytical aerodynamic model is developed to predict the quasi-steady aerodynamic performance of APS using BEM considerations. The theory which assumes a variable inflow is validated against an autogyro and yawed wind turbine. Variation of aerodynamic performance parameters and optimum rotational speed for the rotor of a $300$ kW APS is studied. Moreover, two tether models based on lumped mass modelling approach, one rigid and the other elastic, accounting for reel-in/reel-out had been developed to analyze the coupled dynamics of the tether and airborne modules. The results from the elastic and rigid tether models for a kite power system and an APS show the shortcomings and advantages of one model over the other

Implantation accuracy of novel polyimide stereotactic electroencephalographic depth electrodes—a human cadaveric study

IntroductionStereoelectroencephalography (sEEG) is a minimally invasive procedure that uses depth electrodes stereotactically implanted into brain structures to map the origin and propagation of seizures in epileptic patients. Implantation accuracy of sEEG electrodes plays a critical role in the safety and efficacy of the procedure. This study used human cadaver heads, simulating clinical practice, to evaluate (1) neurosurgeon's ability to implant a new thin-film polyimide sEEG electrode according to the instructions for use (IFU), and (2) implantation accuracy.MethodsFour neurosurgeons (users) implanted 24 sEEG electrodes into two cadaver heads with the aid of the ROSA robotic system. Usability was evaluated using a questionnaire that assessed completion of all procedure steps per IFU and user errors. For implantation accuracy evaluation, planned electrode trajectories were compared with post-implantation trajectories after fusion of pre- and postoperative computer tomography (CT) images. Implantation accuracy was quantified using the Euclidean distance for entry point error (EPE) and target point error (TPE).ResultsAll sEEG electrodes were successfully placed following the IFU without user errors, and post-implant survey of users showed favorable handling characteristics. The EPE was 1.28 ± 0.86 mm and TPE was 1.61 ± 0.89 mm. Long trajectories (>50 mm) had significantly larger EPEs and TPEs than short trajectories (<50 mm), and no differences were found between orthogonal and oblique trajectories. Accuracies were similar or superior to those reported in the literature when using similar experimental conditions, and in the same range as those reported in patients.DiscussionThe results demonstrate that newly developed polyimide sEEG electrodes can be implanted as accurately as similar devices in the marker without user errors when following the IFU in a simulated clinical environment. The human cadaver ex-vivo test system provided a realistic test system, owing to the size, anatomy and similarity of tissue composition to that of the live human brain

Food Supply and Seawater pCO2 Impact Calcification and Internal Shell Dissolution in the Blue Mussel Mytilus edulis

Progressive ocean acidification due to anthropogenic CO2 emissions will alter marine ecosytem processes. Calcifying organisms might be particularly vulnerable to these alterations in the speciation of the marine carbonate system. While previous research efforts have mainly focused on external dissolution of shells in seawater under saturated with respect to calcium carbonate, the internal shell interface might be more vulnerable to acidification. In the case of the blue mussel Mytilus edulis, high body fluid pCO2 causes low pH and low carbonate concentrations in the extrapallial fluid, which is in direct contact with the inner shell surface. In order to test whether elevated seawater pCO2 impacts calcification and inner shell surface integrity we exposed Baltic M. edulis to four different seawater pCO2 (39, 142, 240, 405 Pa) and two food algae (310–350 cells mL−1 vs. 1600–2000 cells mL−1) concentrations for a period of seven weeks during winter (5°C). We found that low food algae concentrations and high pCO2 values each significantly decreased shell length growth. Internal shell surface corrosion of nacreous ( = aragonite) layers was documented via stereomicroscopy and SEM at the two highest pCO2 treatments in the high food group, while it was found in all treatments in the low food group. Both factors, food and pCO2, significantly influenced the magnitude of inner shell surface dissolution. Our findings illustrate for the first time that integrity of inner shell surfaces is tightly coupled to the animals' energy budget under conditions of CO2 stress. It is likely that under food limited conditions, energy is allocated to more vital processes (e.g. somatic mass maintenance) instead of shell conservation. It is evident from our results that mussels exert significant biological control over the structural integrity of their inner shell surfaces

Effective project management of oil and gas projects: a model for oil sands' sagd plants

Bibliography: p. 331-338A few pages are in colour

Studies on the physiological role of taurine (2-aminoethane sulfonic acid) in mammalian tissues

Taurine (2-aminoethane sulfonic acid) is one of the most abundant free amino acids found in mammalian brain, heart and muscle. Taurine levels have also been shown to be altered in certain disease states. A physiological role for taurine in the maintainance of excitatory activity in muscle and nervous tissues has been suggested; however its possible mechanism of action is still uncertain. Early work on the pharmacological actions of taurine involved its possible conversion to isethionic acid (2-hydroxyethane sulfonic acid), a strong anion. This conversion was said to lead to the conductance of cations into the cardiac cell. An analytical technique to measure isethionic acid in mammalian tissues was developed. The method involved extraction, partial purification and methylation with diazomethane, followed by gas-liquid chromatography. With this technique only trace amounts of isethionic acid were detected in rat heart (0.1 mg/lOOg wet weight tissue) and rat brain (0.2 mg per 100 mg wet weight tissue) and none was detected in dog hearts. Recovery of added isethionic acid was between 95 and 100%. The assay was validated using a sample of squid axoplasm. We were also unable to show ¹⁴C-taurine conversion to ¹⁴C-isethionic acid in rat heart slices. Theories on the mode of action of taurine involving bioconversion to isethionic acid were therefore questioned. Some recent work suggested that taurine affects calcium kinetics in perfused guinea-pig hearts and calcium transport in rat skeletal muscle sarcoplasmic reticulum. We have investigated the effect of taurine on ATP-dependent calcium binding and oxalate-dependent calcium uptake in crude preparations of guinea-pig sarcolemma and in microsomal preparations enriched in sarcoplasmic reticulum. Taurine (5-50 mM) was found to have no significant effect on either ATP-dependent Ca²⁺ binding or uptake in both preparations. This result was observed at all calcium concentrations tested (0.5-100 uM) and at all incubation times used (30 seconds to 20 minutes). Taurine (20 mM) neither altered the effect of cyclic AMP-dependent protein kinase on oxalate-dependent calcium uptake nor exerted a stabilization action on calcium transport in these systems. In a further attempt to determine the possible physiological role of taurine in mammalian tissues, we have investigated the effect of taurine on passive transport of sodium, potassium and calcium in synaptosomal preparations of rat brain. Taurine, in a dose dependent manner, was found to have an inhibitory effect on both calcium- uptake and release in these preparations. Amino acids structurally similar to taurine ( β- alanine, homotaurine, hypotaurine and ɣ- aminobutyric acid) were also shown to inhibit calcium uptake in these preparations while a - alanine, proline and valine had no significant effect. Taurine (20 mM), though, did not alter the permeability of these preparations to either sodium or potassium. It thus appeared that taurine, and chemically related amino acids, can specifically alter calcium movements in these preparations. It is suggested that this effect is due to the binding of these agents to taurine receptor sites postulated to be present in these membranes. These observations may help to provide an insight into the physiological and pharmacological effects of taurine reported in cardiac and nervous tissues.Medicine, Faculty ofPathology and Laboratory Medicine, Department ofGraduat

Replication of Oil & Gas Projects: A Model for Achieving Predictability on Oil Sands' SAGD Plants

Replication in some mature industries is quite common and has been very successful. Every automobile manufactured of a certain year and model is identical, and so is every airplane, with a few variations. Every McDonalds restaurant has the same kind of deep fryer, and similar if not identical floor plans. In the oil & gas industry generally, a few examples of Replication exist, but in the oil sands’ Steam Assisted Gravity Drainage (SAGD) industry, it is a relatively new concept. Numerous papers have been written and research done in the oil sands’ sub-surface reservoirs, but little on the building of the surface plants that actually support it during production. A thesis by Halari (2011) recommends Replication as a strategy to mitigate issues encountered during execution of SAGD plants, and forms the genesis of this research. This much required research into Replication of SAGD plants, which includes industry opinion based on experience of over 140 practitioners, identifies the critical factors in executing replicated SAGD plants. Among these, the most significant critical factors found by this study include: • Effective resource development planning; • Standardization as a major design criterion; and • A proper understanding of the Replication concept and effort required to implement. Grounded on the critical factors collected, a SAGD Replication Model is created in this research. It focuses on the four key pillars of Development Economics, Reservoir Planning, Replication Philosophy, and Engineering Design, which SAGD developers need to evaluate based on their company’s respective contexts. Through analysis, this research has also developed some new and interesting concepts such as the inverse relationship between change and Replication, the impact and correlation between time and Replication, and the most important of all, the definition of Replication within the context of oil & gas projects. It is the intent of this initial research to provide a point of reference in developing new projects based on Replication in the oil & gas industry and SAGD in particular. Hopefully, the thinking and concepts it presents will create a dialogue among industry and academia while providing grounds to germinate newer ideas and further research

The legacy of the early twentieth-century Khilafat movement in India

grantor: University of TorontoThis study attempts to look at the legacy of the Khilafat movement in India early this century. The study shows that the abolition of the institution of the Caliphate in Turkey, and the reasons given by the Turkish ' ulama' for its abolition, provided food for thought to the Muslim elite in India. Muslims saw in the reasons for abolition of the Caliphate in Turkey, a process of 'ijtihad' (theological exploration) in which it was possible to update the institution of the Caliphate. This reflection made it possible to demand, from the British government and the Indian National Congress, an Islamic state. Such a development emerged as the legacy of the Khilafat movement. As Muhammad Ali Jinnah (1876-1948) took up this challenge, he used a three-pronged approach to sell the idea to the Muslim masses. After tracing earlier views of the Caliphate this study looks at the connotations of the 'Ashura event (the martyrdom of Imam al-Husayn, the grandson of Prophet Muhammad) in Karbala, which occurred in the year 61 A.H. (685 C.E.), and its commemoration every year, to show how recalling this event helped Jinnah in his Pakistan movement. The study shows that the khilafatist leaders were involved in using the 'Ashura event in Karbala to motivate Muslims. The study also presents writings and compositions of poems using the 'Ashura event to arouse Muslims, literature recently (1986) released in the material proscribed by the British government in the 1920's and 1930's. Finally, the study shows that in the thinking of twentieth-century Indian Muslims the institutional rationale of the Caliphate seems to have evolved, from a one-man Caliph-emperor to a socially elected, democratic caliphal state, from the idea of an individual Caliph to the concept of an Islamic state.Ph.D