On the natural convection boundary layer adjacent to an inclined flat plate subject to ramp heating

An investigation of the natural convection boundary layer adjacent to an inclined semi-infinite plate subject to a temperature boundary condition which follows a ramp function up until some specified time and then remains constant is reported. The development of the flow from start-up to a steadystate has been described based on scaling analyses and verified by numerical simulations. Attention in this study has been given to fluids having a Prandtl number Pr less than unity. The boundary layer flow depends on the comparison of the time at which the ramp heating is completed and the time at which the boundary layer completes its growth. If the ramp time is long compared with the steady state time, the layer reaches a quasi steady mode in which the growth of the layer is governed solely by the thermal balance between convection and conduction. On the other hand, if the ramp is completed before the layer becomes steady; the subsequent growth is governed by the balance between buoyancy and inertia, as for the case of instantaneous heating.

Successes and stresses : A case study on relations between international higher degree students in Australia and their universities.

The paper examines the situation of postgraduate international students studying in Australia, mostly at doctoral level; a group widely seen as sought-after by Australian universities and employers, though also exposed to difficulties in aspects like learning culture, language and temporary employment. The investigation follows a novel path, as an exercise in practice-led research on issues involved in Higher Degree supervision. It is in fact an exercise within an advanced program of professional development for HD research supervisors. It begins by deploying a journalistic method, to obtain and present information. This has entailed the publishing of two feature articles about the lives of scholars for Subtropic, a campus based online magazine in Brisbane, www.subtropic.com.au. The next step is a review of a set of supervisions, citing issues raised in individual cases. Parallels can be seen between the two information-getting and analytical processes, with scope for contradictions. An exegetical statement deals with supervisory issues that have been exposed, and implications for learning, with recommendations for developing the quality of the experience of these students.

Diversity in product familiarity across younger and older adults

This paper reports on the findings of a completed experiment examining levels of familiarity in younger and older adults. Research has shown that older adults use products less intuitively than younger adults, and that familiarity is an essential element of intuitive interaction. This finding influenced the decision to focus on familiarity and to investigate why older adults use products less intuitively than younger adults. By identifying and understanding the differences in familiarity, it is hypothesised that designers will be able to design more usable products for older adults. An empirical study was conducted, investigating the differences in familiarity between younger and older adults with contemporary products. Younger adults demonstrate significantly higher levels of familiarity compared to older adults, and the three groups of older adults demonstrated no significant differences between them. The implications of this finding is discussed.

General characteristics of anticipated user experience (AUX) with interactive products

Providing a positive user experience (UX) has become the key differentiator for products to win a competition in mature markets. To ensure that a product will support enjoyable experiences for its users, assessment of UX should be conducted early during the design and development process. However, most UX frameworks and evaluation techniques focus on understanding and assessing user’s experience with functional prototypes or existing products. This situation delays UX assessment until the late phases of product development which may result in costly design modifications and less desirable products. A qualitative study was conducted to investigate anticipated user experience (AUX) to address this issue. Twenty pairs of participants were asked to imagine an interactive product, draw their product concept, and anticipate their interactions and experiences with it. The data was analyzed to identify general characteristics of AUX. We found that while positive AUX was mostly related to an imagined/desired product, negative AUX was mainly associated with existing products. It was evident that the pragmatic quality of product was fundamental, and significantly influenced user’s anticipated experiences. Furthermore, the hedonic quality of product received more focus in positive than negative AUX. The results also showed that context, user profile, experiential knowledge, and anticipated emotion could be reflected in AUX. The understanding of AUX will help product designers to better foresee the users’ underlying needs and to focus on the most important aspects of their positive experiences, which in turn facilitates the designers to ensure pleasurable UX from the start of the design process.

Distribution feeder voltage support and power factor control by distributed multiple inverters

The potential of distributed reactive power control to improve the voltage profile of radial distribution feeders has been reported in literature by few authors. However, the multiple inverters injecting or absorbing reactive power across a distribution feeder may introduce control interactions and/or voltage instability. Such controller interactions can be alleviated if the inverters are allowed to operate on voltage droop. First, the paper demonstrates that a linear shallow droop line can maintain the steady state voltage profile close to reference, up to a certain level of loading. Then, impacts of the shallow droop line control on line losses and line power factors are examined. Finally, a piecewise linear droop line which can achieve reduced line losses and close to unity power factor at the feeder source is proposed.

Researching intuitive interaction

Intuitive interaction is based on past experience and is fast and often non conscious. We have conducted ten studies into this issue over the past ten years, involving more than 400 participants. Data collection methods have included questionnaires, interviews, observations, concurrent and retrospective protocols, and cognitive measures. Coding schemes have been developed to suit each study and involve robust, literature based heuristics. Some other researchers have investigated this issue and their methods are also examined. The paper traces the development of the methods and compares the various approaches used over the years.

An experimental study of a reactive plume in grid turbulence

Experimental results for a reactive non-buoyant plume of nitric oxide (NO) in a turbulent grid flow doped with ozone (O3) are presented. The Damkohler number (Nd) for the experiment is of order unity indicating the turbulence and chemistry have similar timescales and both affect the chemical reaction rate. Continuous measurements of two components of velocity using hot-wire anemometry and the two reactants using chemiluminescent analysers have been made. A spatial resolution for the reactants of four Kolmogorov scales has been possible because of the novel design of the experiment. Measurements at this resolution for a reactive plume are not found in the literature. The experiment has been conducted relatively close to the grid in the region where self-similarity of the plume has not yet developed. Statistics of a conserved scalar, deduced from both reactive and non-reactive scalars by conserved scalar theory, are used to establish the mixing field of the plume, which is found to be consistent with theoretical considerations and with those found by other investigators in non-reative flows. Where appropriate the reactive species means and higher moments, probability density functions, joint statistics and spectra are compared with their respective frozen, equilibrium and reaction-dominated limits deduced from conserved scalar theory. The theoretical limits bracket reactive scalar statistics where this should be so according to conserved scalar theory. Both reactants approach their equilibrium limits with greater distance downstream. In the region of measurement, the plume reactant behaves as the reactant not in excess and the ambient reactant behaves as the reactant in excess. The reactant covariance lies outside its frozen and equilibrium limits for this value of Vd. The reaction rate closure of Toor (1969) is compared with the measured reaction rate. The gradient model is used to obtain turbulent diffusivities from turbulent fluxes. Diffusivity of a non-reactive scalar is found to be close to that measured in non-reactive flows by others.

Categorising emotional experiences with portable interactive devices

This paper reports on a six month longitudinal study exploring people’s emotional experience with two categories of portable interactive devices (PIDs); media and health related PIDs. The focus is on emotions and how PIDs mediate these experiences in everyday contexts. Previous findings presented by the authors (Gomez 2009, 2010) revealed that people’s emotional experiences with PIDs over time are influenced by whether interactions were at a personal or social level. This paper presents four categories of activities identified and their relationship to emotional experiences with PIDs that have been developed through further analysis of the data. It concludes with a discussion of the findings and their implications to the field of Design on the design of future PIDs.

An approach for current balancing in distribution networks with rooftop PVs

Current unbalance is a significant power quality problem in distribution networks. This problem increases further with the increased penetration of single-phase photovoltaic cells. In this paper, a new approach is developed for current unbalance reduction in medium voltage distribution networks. The method is based on utilization of three single-phase voltage source converters connected in delta configuration between the phases. Each converter is controlled to function as a varying capacitor. The combination of the load and the compensator will result in a balanced load with unity power factor. The efficacy of the proposed current unbalance reduction concept is verified through dynamic simulations in PSCAD/EMTDC.

Seeking inclusion : views from ‘vulnerable’ communities about reporting by the Australian news media

This conference paper reports on the findings of the 'Vulnerability and the News Media’ project about news reporting on communities that are commonly regarded as ‘vulnerable’ by virtue of their issues or circumstances. The project focuses on news reporting of Indigenous and ethnically diverse communities, as well as people affected by mental health issues, people with disabilities, and survivors of crime and traumatic events. Numerous educational initiatives have tried to improve the quality of media reports about these communities and their issues. Despite this, the project’s research with stakeholders from those communities has found that they continue to raise the same concerns that have been expressed about the news media since the 1970s. In focus group research, stakeholders from these communities expressed concern about their continuing under-representation or omission from the news media. They felt that voices, experiences, perspectives and issues from their communities rarely appeared, or if they did appear, it was in limited contexts – often in circumstances that portrayed them as vulnerable or disruptive. They also pointed to ongoing media misrepresentation, such as stereotyping, inappropriate framing, and over-reliance on ‘usual suspects’ to talk about their communities. A common theme that they voiced was their need for greater inclusiveness in the media. Participants wished that journalists would better represent the diversity of life experiences and perspectives within their communities. Stakeholders also wanted an increased in representation of their political frameworks, such as stories about the difficulties they encountered in dealing with social and bureaucratic systems, and their understandings of causes and potential solutions for issues affecting their communities.

Playing with Picturebooks : Postmodernism and the Postmodernesque

Postmodernism has played a significant part in the development of playful and experimental picturebooks for children over the past 50 years. Playing with Picturebooks offers fresh insights into the continuing influence of postmodernism on picturebooks for children, covering a wide range of international picturebooks predominantly from the 1980s to the present. It represents a significant contribution to current debates centred on the decline of the effects of postmodernism on fiction and detects a shift from the postmodern to the postmodernesque. Playing with Picturebooks draws on a wide range of critical perspectives in examining postmodern approaches to narrative and illustration. Chapters discuss how metafictive devices enable different modes of representation, offer different perspectives to authorised version of history, and promote difference and ex-centricity over unity. Playing with Picturebooks is essential reading, not only for academics in the field of children's literature, but also for researchers, teachers and students

Thermo-magnetic convection of paramagnetic fluids with non-instantaneous heating

The unsteady boundary-layer development for thermomagnetic convection of paramagnetic fluids inside a square cavity has been considered in this study. The cavity is placed in a microgravity condition (no gravitation acceleration) and under a uniform magnetic field which acts vertically. A ramp temperature boundary condition is applied on left vertical side wall of the cavity where the temperature initially increases with time up to some specific time and maintain constant thereafter. A distinct magnetic convection boundary layer is developed adjacent to the left vertical wall due to the effect of the magnetic body force generated on the paramagnetic fluid. An improved scaling analysis has been performed using triple-layer integral method and verified by numerical simulations. The Prandtl number has been chosen greater than unity varied over 5-100. Moreover, the effect of various values of the magnetic parameter and magnetic Rayleigh number on the fluid flow and heat transfer has been shown.

A pre-treatment verification tool for IMRT based on EPID measurements and a GEANT4 back projection application

The aim of this work is to develop software that is capable of back projecting primary fluence images obtained from EPID measurements through phantom and patient geometries in order to calculate 3D dose distributions. In the first instance, we aim to develop a tool for pretreatment verification in IMRT. In our approach, a Geant4 application is used to back project primary fluence values from each EPID pixel towards the source. Each beam is considered to be polyenergetic, with a spectrum obtained from Monte Carlo calculations for the LINAC in question. At each step of the ray tracing process, the energy differential fluence is corrected for attenuation and beam divergence. Subsequently, the TERMA is calculated and accumulated to an energy differential 3D TERMA distribution. This distribution is then convolved with monoenergetic point spread kernels, thus generating energy differential 3D dose distributions. The resulting dose distributions are accumulated to yield the total dose distribution, which can then be used for pre-treatment verification of IMRT plans. Preliminary results were obtained for a test EPID image comprised of 100 9 100 pixels of unity fluence. Back projection of this field into a 30 cm9 30 cm 9 30 cm water phantom was performed, with TERMA distributions obtained in approximately 10 min (running on a single core of a 3 GHz processor). Point spread kernels for monoenergetic photons in water were calculated using a separate Geant4 application. Following convolution and summation, the resulting 3D dose distribution produced familiar build-up and penumbral features. In order to validate the dose model we will use EPID images recorded without any attenuating material in the beam for a number of MLC defined square fields. The dose distributions in water will be calculated and compared to TPS predictions.

Preparation and characterization of TiO2/acid leached serpentinite tailings composites and their photocatalytic reduction of Chromium(VI)

Composite TiO2/acid leached serpentine tailings (AST) were synthesized through the hydrolysis–deposition method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energydispersive X-ray spectrometry (EDS), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and surface area measurement (BET). The XRD analysis showed that TiO2 coated on the surface of acid leached serpentine tailings was mixed crystal phases of rutile and anatase, the grain size of which is 10–30 nm. SEM, TEM, and EDS analysis exhibited that nano-TiO2 particles were deposited on the surface and internal cavities of acid leaching serpentine tailings. The XPS and FT-IR analysis demonstrated that the coating process of TiO2 on AST was a physical adsorption process. The large specific surface area, porous structure, and plentiful surface hydroxyl group of TiO2/AST composite resulted in the high adsorption capacity of Cr(VI). The experimental results demonstrated that initial concentration of Cr(VI), the amount of the catalyst, and pH greatly influenced the removal efficiency of Cr(VI). The removal kinetics of Cr(VI) at a relative low initial concentration was fitted well with Langmuir–Hinshelwood kinetics model with R2 value of about unity. The asprepared composites exhibited strong adsorption and photocatalytic capacity for the removal of Cr(VI), and the possible photocatalytic reduction mechanism was studied. The photodecomposition of Cr(VI) was as high as 95% within 2 h, and the reusability of the photocatalysis was proven.

Monte Carlo-based diode design for correction-less small field dosimetry

Due to their small collecting volume diodes are commonly used in small field dosimetry. However the relative sensitivity of a diode increases with decreasing small field size. Conversely, small air gaps have been shown to cause a significant decrease in the sensitivity of a detector as the field size is decreased. Therefore this study uses Monte Carlo simulations to look at introducing air upstream to diodes such that they measure with a constant sensitivity across all field sizes in small field dosimetry. Varying thicknesses of air were introduced onto the upstream end of two commercial diodes (PTW 60016 photon diode and PTW 60017 electron diode), as well as a theoretical unenclosed silicon chip using field sizes as small as 5 mm × 5 mm . The metric D_(w,Q)/D_(Det,Q) used in this study represents the ratio of the dose to a point of water to the dose to the diode active volume, for a particular field size and location. The optimal thickness of air required to provide a constant sensitivity across all small field sizes was found by plotting D_(w,Q)/D_(Det,Q) as a function of introduced air gap size for various field sizes, and finding the intersection point of these plots. That is, the point at which D_(w,Q)/D_(Det,Q) was constant for all field sizes was found. The optimal thickness of air was calculated to be 3.3 mm, 1.15 mm and 0.10 mm for the photon diode, electron diode and unenclosed silicon chip respectively. The variation in these results was due to the different design of each detector. When calculated with the new diode design incorporating the upstream air gap, k_(Q_clin 〖,Q〗_msr)^(f_clin 〖,f〗_msr ) was equal to unity to within statistical uncertainty (0.5 %) for all three diodes. Cross-axis profile measurements were also improved with the new detector design. The upstream air gap could be implanted on the commercial diodes via a cap consisting of the air cavity surrounded by water equivalent material. The results for the unclosed silicon chip show that an ideal small field dosimetry diode could be created by using a silicon chip with a small amount of air above it.