116 resultados para Super-conducting coils


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This thesis explores the chaotic, dynamic, ambiguous, complex and confusing world of the insider researcher. The proliferating species of insider researcher is common in public sector organisations and is particularly prevalent among post-graduate students who have combined study with work. Insider researchers range from the in-house researcher employed to conduct research to those who are conducting research in addition to their normal duties. This thesis, through five illustrative case-studies, discusses, reflects upon, explains, and clarifies the possibilities, limitations and the issues arising from a consideration of the practice of professionals conducting research in the large government education system in Victoria. The central focus of this thesis, that of exploring issues arising from professionals conducting research in their own working environments, has an importance that hitherto has had little direct recognition in the qualitative education research literature. And yet the practice of insider research is common and has a potentially large impact on the nature of the decision making process in public sector organisations. This relative invisibility in the social research literature of a discussion of issues relating to insider research demands to be made more visible. It is both useful and necessary to explore the particular possibilities, conditions and challenges of insiders conducting research in public organisations as the practice of insider research contines to grow. This thesis adds to the literature by locating insider research in a discussion of the wider soial context of ideology, culture, relationships, politics, language and meaning, and the decision-making process.

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Drawing upon one research project Home-School-Community Partnerships for Enhancing Children's Numeracy Development we examine, critically, some problems entailed in the processes of conceptualizing the subjects and objects of inquiry, conducting field work with subjects (as knowing agents) and interpreting and disseminating the knowledge gained. Addressing these issues, in practice, has entailed some necessary consideration of fundamental tensions centred around the professional power-knowledge of teachers and a dominant cultural discourse that situates numeracy learning in the school.

A theoretical model (based upon Engeström's Activity Theory) was used to specify and analyse various types of partnerships within a network of mutually interconnected activities to support children's learning (Bloome et al., 2000; Engeström, 1999). By decentering the school, within this model, we have been led to a closer analysis of the concept of 'partnership' and of the social construction of parental and community involvement in children's numeracy development. One of the most problematic aspects of partnerships evident in our research is the way in which the term 'numeracy' is understood by different stakeholders. Awareness of this has shaped the conduct and dissemination of our research and ultimately enabled us to identify critical issues for further inquiry.

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This paper reports on some physical properties of a conducting polymer, polypyrrole, coated textiles. Polypyrrole was coated on textiles chemically through in-situ solution or vapor polymerisation to produce conducting textiles. The effects of the conductive coating on the physical and mechanical properties of the fibrous materials are presented. The coating durability and conductivity of the textiles have also been examined.

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This research developed non-hazardous methods for coating wool with conductive polymers for thermal and anti-static clothing. Conductive polymers are black in colour, thus the synthesis of new conductive polymers was required to produce coloured or fluorescent conductive textile. Cross-linked conductive polymers were also synthesised to increase their durability.

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This investigation of textiles coated with a polymer that conducts electricity showed that they can be used for effectively reflecting and absorbing microwaves. These conducting textiles are an economical, flexible and lightweight alternative to traditional materials for electromagnetic interference shielding of, for instance, sensitive electronic equipment.

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Electrochemical synthesis of a tri-layer polypyrrole based actuator optimized for performance was reported. The 0.05 M pyrrole and 0.05 M tetrabutylammonium hexaflurophosphate in propylene carbonate (PC) yielded the optimum performance and stability. The force produced ranged from 0.2 to 0.4mN. Cyclic deflection tests on PC based actuators for 3 hours indicated that the displacement decreased by 60%. PC based actuator had a longer operating time, exceeding 3 hours, compared to acetonitrile based actuators. A triple-layer model of the polymer actuator was developed based on the classic bending beam theory by considering strain electrode material. A tri-layer actuator was fabricated [4, 6], by initially sputter coating a PVDF film with approximately 100nm of gold layer, resulting in a conductive film with a surface resistance of 8-10Ω. The PVDF film was about ~145µm thick had an approximate pore size of 45μm. A solution containing 0.05M distilled pyrrole monomer, 0.05M (TBAPF6) and 1% (w/w) distilled water in PC (propylene carbonate) solution was purged with nitrogen for 15 minutes. The continuity between PPy and PVDF. Results predicted by the model were in good agreement with the experimental data.

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The lithium fast-ion conductor, Li1+xAlxTi2−x(PO4)3 (LATP) has been modified via changes in stoichiometry during the processing steps. The resultant changes have been followed using 27Al MAS NMR, X-ray powder diffraction and impedance spectroscopy. The most important changes were those of the form Li1.3+4yAl0.3Ti1.7−y(PO4)3. It was possible to remove the AlPO4 phase (both tridymite and berlinite polymorphs), as monitored by X-ray diffractograms and 27Al NMR spectra. Consequently, these changes appear to result in increased grain boundary conductivity of the LATP material.

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Carbon black (CB) fillers were used to study the feasibility of achieving multiple percolation using an immiscible (polar) polymer blend matrix. By tailoring the morphology of the insulating dual phase matrix it has been shown that the percolation threshold (Фc) can be reduced over single-phase matrices. Cocontinuity in the polymer matrix is important in reducing Фc by either preferentially isolating the conducting filler at the interface of the two phases or within one particular continuous phase of the matrix thereby forming a continuous conducting network within a continuous network (multiple percolation). Actual melt processing time has been found to influence the dispersion of the fillers and hence Фc. Polarity of the matrix as well as the processing method has also been found to influence the dispersion of the filler within the host polymer.

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X-ray diffraction (XRD) was employed to characterize electrochemically synthesized polypyrrole (PPy) films with 1,5-naphthalene disulfonate (1,5-NDS) counterions treated with simple acid and base. Results show that the as-synthesized film is amorphous with short-range ordering in the polymer backbone. This ordering is soon lost after thermal ageing at 150°C for 60 days and there is evidence of counterion degradation. Base treatment of the PPy/1,5-NDS films has similar effects leading to a complete loss of ordering in the polymer backbone and dedoping of the polymer. Acid treatment at high temperatures increases the ordering of the polymer backbone and results in the development of a secondary interdopant peak confirming that ion exchange has occurred. Conductivity of the PPy was also increased substantially. The enhanced ordering was maintained even after thermal ageing. Room-temperature acid treatment also results in improved ordering of the polymer as well as the counterion but the increase in conductivity is only marginal and most of the ordering is soon lost after thermal ageing. Increase in ordering of the polymer structure seems to lead to better conductivity, although not necessarily improved thermal stability.

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Electrochemically synthesised polypyrrole (PPy) with 1,5 naphthalene disulfonate (1,5-NDS) counterions treated with simple acid and base was characterised using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The as synthesised film was found to be amorphous with short-range ordering in the polymer backbone. Ordering was lost after thermal ageing with evidence of counterion degradation. Base treatment lead to loss of ordering as well as dedoping of the polymer whereas acid treatment at high temperature increases short range ordering. Conductivity was also increased dramatically with evidence of ion exchange. Ordering induced by the treatment was maintained even after thermal ageing.

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The use of ionic liquids (ILs) as electrolytes for electromechanical actuators based on polypyrroles (PPy's) is described. The composition of the electrolytes has a significant effect on the electrochemical properties of the PPy actuator and subsequently on actuator performance, improving cycle life and strain generated. The actuator performance in ionic liquid electrolytes is significantly better than that in traditional organic and aqueous electrolytes.