977 resultados para DIELECTRIC REFLECTION GRATINGS


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Pacific Rim Real Estate Society has conducted four property case competitions from 2009 to 2012. The competition provides opportunities for undergraduate students to present their proposal on a given case study. All students were locked down with their four team members for five hours without external help to ensure a level playing field across participants. Students prepared their presentation and defended their arguments in front of experts in property industry and academia. The aim of this paper is reflecting on the feedback received from stakeholders involved in the case competition. Besides exploring what students have gained from the competitions, this paper provides an insight on the opportunities and challenges for the new format of competition to be introduced in 2013. Over the last four competitions, there were three universities participated in all the four consecutive events, four universities partook in two events and another four universities only competed once. Some universities had a great advantage by having previous experiences by participating in similar international business competitions. Findings show that the students have benefited greatly from the event including improving their ability in problem solving and other non-technical skills. Despite the aforementioned benefits, the PRRES closed-book case competition is proven not viable thus future competition needs to minimise the travel and logistic cost.

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The benefits of reflective practice have been well established in the literature (Rogers, 2001), as have models to embed reflective thinking in higher education curriculum (Ryan and Ryan, 2012). Reflection is commonly envisaged as a textual practice, through which students ‘reflect in and on action’ (Schön 1983), and articulate their experiences, learning and outcomes in written portfolios, journals, or blogs. While such approaches to individual written reflection are undoubtedly beneficial for deepening insight and self-criticality, reflection can also provide other benefits when approached as a collaborative, oral activity. This poster presents a dialogic model of reflective practice that affords the opportunity for developing presentation skills, critique, community and professional identity formation. This dialogic approach to reflection is illustrated by a first year subject (‘KIB101 Visual Communication’ at QUT), in which students apply visual theory (presented in lectures) to communication and graphic design problems in the studio. In regular (fortnightly) presentations, they critically reflect upon their work in progress by aligning it with the concepts, design principles and professional language of the lectures. This iterative process facilitates responsive peer feedback, similarly couched in the formal terms of the discipline. This ‘mirrored reflection’ not only provides opportunities to incrementally improve, it also sets designs in a theoretical frame; provides the opportunity for comparative analysis (to see design principles applied by peers in different ways); to practice formal design language and presentation techniques of the discipline and; because peer critique is framed as an act of generosity; it affords the development of a supportive community of practice. In these ways, dialogic reflection helps students develop a professional voice and identity from first year. Evidence of impact is provided by quantitative and qualitative student feedback over several years, as well as institutional feedback and recognition.

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Thin film supercapacitors are produced by using electrochemically exfoliated graphene (G) and wet-chemically produced graphene oxide (GO). Either G/GO/G stacked film or sole GO film are sandwiched by two Au films to make devices, where GO is the dielectric spacer. The addition of graphene film for charge storage can increase the capacitance about two times, compared to the simple Au electrode. It is found that the GO film has very high dielectric constant, accounting for the high capacitance of these devices. AC measurements reveal that the relative permittivity of GO is in the order of 104 within the frequency range of 0.1–70 Hz.

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Research into the human dynamics of expeditions is a potentially rewarding and fruitful area of study. However, the complex nature of expedition work presents the researcher with numerous challenges. This paper presents a personal reflection on the challenges linked to determining appropriate methodological processes for a study into expedition teamwork. Previous expedition research is outlined and reviewed for appropriateness. Some alternative methodological theories are described and limitations highlighted. Lastly the actual data gathering and analysis processes are detailed. The aim being to show that what happened in the field inevitably dictated how methodological processes were adapted. Essentially the paper describes a personal journey into research. A journey that sparked numerous personal insights in the science of human dynamics and expeditions and one that I hope will add to the development of expedition research in general.

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Despite the importance of the school-based practicum experience in teacher education programs, only limited research has investigated how supervising and pre-service teacher roles and relationships are interactively achieved in situ. Using conversation analysis, we interrogate extracts of practicum talk between supervising teachers (STs) and their pre-service teachers (PTs), revealing that asymmetrical relationships are talked into being within and through their conversations about classroom practice. We compare the different structural conversational arrangements that are employed when STs provide either positive feedback or raise issues of potential difficulty in relation to their PTs’ observed classroom activities. Analysis reveals that STs tend to make evaluative statements when providing positive feedback, in contrast to initiating a process of critical reflection when talking about the need for improvements in PTs’ pedagogic practices. We conclude by arguing the need for STs to instigate sustained critical and collaborative professional conversations with their PTs during the practicum experience, enabling them to engage in reflective practice and providing them with opportunities to extend their professional knowledge and skills, thereby potentially improving their future classroom practices.

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Frequency Domain Spectroscopy (FDS) is used to assess the insulation condition of oil-paper power transformers. Dissipation factor is one of the conventional indicators to analyze insulation ageing status. In this paper, the imaginary admittance of the transformers insulation, after removal of the geometric capacitance, is proposed as an alternative indicator to assist in the interpretation of ageing status. Ageing effects on the imaginary admittance are investigated both through simulation results and experimental results.

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Ground-penetrating radar (GPR) is widely used for assessment of soil moisture variability in field soils. Because GPR does not measure soil water content directly, it is common practice to use calibration functions that describe its relationship with the soil dielectric properties and textural parameters. However, the large variety of models complicates the selection of the appropriate function. In this article an overview is presented of the different functions available, including volumetric models, empirical functions, effective medium theories, and frequency-specific functions. Using detailed information presented in summary tables, the choice for which calibration function to use can be guided by the soil variables available to the user, the frequency of the GPR equipment, and the desired level of detail of the output. This article can thus serve as a guide for GPR practitioners to obtain soil moisture values and to estimate soil dielectric properties.

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Polymeric nanocomposites have been shown to possess superior electrical insulation properties compared to traditional filled-resins. However, poor dispersion uniformity and insufficient filler-matrix interaction can adversely affect insulation properties of nanocomposites. In this study, the use of plasma polymerization is proposed to coat poly(ethylene oxide) polymer layers on silica nanoparticles. It is shown that better dispersion is achieved and C-O bonds are created between the surface functional groups of the nanoparticles and the host epoxy polymer. Electrical insulation tests demonstrate that the nanocomposites with plasma polymerized silica nanoparticles feature better resistance against electrical treeing, lower dielectric constant, and also mitigated space charge built-up. Therefore, plasma polymerization offers a promising fabrication technique to further improve the synthesis of nanocomposite dielectrics with superior electrical insulation properties.

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In this study, atmospheric-pressure plasmas were applied to modify the surface of silane-coated silica nanoparticles. Subsequently nanocomposites were synthesized by incorporating plasma-treated nanoparticles into an epoxy resin matrix. Electrical testing showed that such novel dielectric materials obtained high partial discharge resistance, high dielectric breakdown strength, and enhanced endurance under highly stressed electric field. Through spectroscopic and microscopic analysis, we found surface groups of nanoparticles were activated and radicals were created after the plasma treatment. Moreover, a uniform dispersion of nanoparticles in nanocomposites was observed. It was expected that the improved dielectric performance of the nanocomposites can attribute to stronger chemical bonds formed between surface groups of plasma-treated nanoparticles and molecules in the matrix. This simple yet effective and environmentally friendly approach aims to synthesize the next generation of high-performance nanocomposite dielectric insulation materials for applications in high-voltage power systems.

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We report on the application of cold atmospheric-pressure plasmas to modify silica nanoparticles to enhance their compatibility with polymer matrices. Thermally nonequilibrium atmospheric-pressure plasma is generated by a high-voltage radio frequency power source operated in the capacitively coupled mode with helium as the working gas. Compared to the pure polymer and the polymer nanocomposites with untreated SiO2, the plasma-treated SiO2–polymer nanocomposites show higher dielectric breakdown strength and extended endurance under a constant electrical stress. These improvements are attributed to the stronger interactions between the SiO2 nanoparticles and the surrounding polymer matrix after the plasma treatment. Our method is generic and can be used in the production of high-performance organic–inorganic functional nanocomposites.

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The Ar/O2plasma needle in the induction of A549 cancer cells apoptosis process is studied by means of real-time observation. The entire process of programmed cell death is observed. The typical morphological changes of A549 apoptosis are detected by 4′, 6-diamidino-2-phenylindole staining, for example, chromatin condensation and nuclear fragmentation. Cell viability is determined and quantified by neutral red uptake assay, and the survival rate of A549 from Ar/O2plasmas is presented. Further spectral analysis indicates the reactive species, including O and OH play crucial roles in the cell inactivation.

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An effective technique to improve the precision and throughput of energetic ion condensation through dielectric nanoporous templates and reduce nanopore clogging by using finely tuned pulsed bias is proposed. Multiscale numerical simulations of ion deposition show the possibility of controlling the dynamic charge balance on the upper template's surface to minimize ion deposition on nanopore sidewalls and to deposit ions selectively on the substrate surface in contact with the pore opening. In this way, the shapes of nanodots in template-assisted nanoarray fabrication can be effectively controlled. The results are applicable to various processes involving porous dielectric nanomaterials and dense nanoarrays.

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The theory of ion-acoustic surface wave propagation on the interface between a dusty plasma and a dielectric is presented. Both the constant and variable dust-charge cases are considered. It is found that massive negatively charged dust grains can significantly affect the propagation and damping of the surface waves. Application of the results to surface-wave generated plasmas is discussed. © 1998 IEEE.

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The results of multi-scale numerical simulations of pulsed i-PVD template-assisted nanofabrication of ZnO nanodot arrays on a silicon substrate are presented. The ratios and spatial distributions of the ion fluxes deposited on the lateral and bottom surfaces of the nanopores are computed as a function of the external bias and plasma parameters. The results show that the pulsed bias plays a significant role in the ion current distribution inside the nanopores. The results of numerical experiments of this work suggest that by finely adjusting the pulse voltage, the pulse duration and the duty cycle of the external pulsed bias, the nanopore clogging can be successfully avoided during the deposition and the shapes of the deposited ZnO nanodots can be effectively controlled. A figure is presented.

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A theoretical model of a large-area planar plasma producer based on surface wave (SW) propagation in a plasma-metal structure with a dielectric sheath is presented. The SW which produces and sustains the microwave gas discharge in the planar structure propagates along an external magnetic field and possesses an eigenfrequency within the range between electron cyclotron and electron plasma frequencies. The spatial distributions of the produced plasma density, electromagnetic fields, energy flow density, phase velocity and reverse skin depth of the SW are obtained analytically and numerically.