Systematic selection of analogue redesign method for forward-type digital power converters

This article proposes a systematic approach to determine the most suitable analogue redesign method to be used for forward-type converters under digital voltage mode control. The focus of the method is to achieve the highest phase margin at the particular switching and crossover frequencies chosen by the designer. It is shown that at high crossover frequencies with respect to switching frequency, controllers designed using backward integration have the largest phase margin; whereas at low crossover frequencies with respect to switching frequency, controllers designed using bilinear integration with pre-warping have the largest phase margins. An algorithm has been developed to determine the frequency of the crossing point where the recommended discretisation method changes. An accurate model of the power stage is used for simulation and experimental results from a Buck converter are collected. The performance of the digital controllers is compared to that of the equivalent analogue controller both in simulation and experiment. Excellent closeness between the simulation and experimental results is presented. This work provides a concrete example to allow academics and engineers to systematically choose a discretisation method.

Nonlinear identification using orthogonal forward regression with nested optimal regularization

An efficient data based-modeling algorithm for nonlinear system identification is introduced for radial basis function (RBF) neural networks with the aim of maximizing generalization capability based on the concept of leave-one-out (LOO) cross validation. Each of the RBF kernels has its own kernel width parameter and the basic idea is to optimize the multiple pairs of regularization parameters and kernel widths, each of which is associated with a kernel, one at a time within the orthogonal forward regression (OFR) procedure. Thus, each OFR step consists of one model term selection based on the LOO mean square error (LOOMSE), followed by the optimization of the associated kernel width and regularization parameter, also based on the LOOMSE. Since like our previous state-of-the-art local regularization assisted orthogonal least squares (LROLS) algorithm, the same LOOMSE is adopted for model selection, our proposed new OFR algorithm is also capable of producing a very sparse RBF model with excellent generalization performance. Unlike our previous LROLS algorithm which requires an additional iterative loop to optimize the regularization parameters as well as an additional procedure to optimize the kernel width, the proposed new OFR algorithm optimizes both the kernel widths and regularization parameters within the single OFR procedure, and consequently the required computational complexity is dramatically reduced. Nonlinear system identification examples are included to demonstrate the effectiveness of this new approach in comparison to the well-known approaches of support vector machine and least absolute shrinkage and selection operator as well as the LROLS algorithm.

Looking back, moving forward: drama, disability and social justice

The aim of this chapter is to briefly outline how disability has been represented in theatre, what access disabled people have had to drama and theatre in the past, and what might be achieved in the pursuit of social justice with young people in relation to awareness of and provision for disability. It will focus in particular on how disability has been addressed in drama education and what assumptions have been made regarding drama and disability in education. In considering such issues one might perceive manifestations of what Freebody and Finneran (2013) recognise as an overlapping and ‘somewhat artificially created dichotomy between drama for social justice and drama about social justice.’ This chapter will examine some examples of how drama has been used to give students in mainstream schools insights into disability, and the philosophy that underpins the drama curriculum of one special school where the focus is on drama as social justice: the argument being that in some cases simply doing drama is, in effect, a manifestation of social justice. Finally, some of the progress made in recent years regarding access and engagement will be addressed through specific reference to the authors’ on-going work into ‘performing social research’ (Shah, 2013) and how theatres are increasingly attempting to give more access to disabled young people and their families by offering ‘relaxed performances.’

Vocabulary acquisition in young children: the role of the story

Sharing storybooks with babies increases their future achievements in literacy, especially in reading (Hall, 2001; Moore and Wade, 1997, 2003; Scarborough et al., 1991; Wade and Moore, 1998; Wells, 1985). This study, focusing on case studies of two 20-month-old children, attempts to identify the role the storybook plays in children’s vocabulary acquisition. Their mothers adopted a regime of daily reading of specific picture books over a six-week period, and recorded the children’s acquisition of new vocabulary, in order to explore what specific contribution these texts made to the children’s speech. The findings demonstrate that storybooks form one source of children’s newly-acquired vocabulary. Factors that might account for this were more difficult to determine through a study of this scale.

An open book: what and how young children learn from picture and story books

Looking at and listening to picture and story books is a ubiquitous activity, frequently enjoyed by many young children and their parents. Well before children can read for themselves they are able to learn from books. Looking at and listening to books increases children’s general knowledge, understanding about the world and promotes language acquisition. This collection of papers demonstrates the breadth of information pre-reading children learn from books and increases our understanding of the social and cognitive mechanisms that support this learning. Our hope is that this Research Topic/eBook will be useful for researchers as well as educational practitioners and parents who are interested in optimizing children’s learning. We conceptually divide this research topic into four broad sections, which focus on the nature and attributes of picture and story books, what children learn from picture and story books, the interactions children experience during shared reading, and potential applications of research into shared reading, respectively.

One step forward, and two steps back: women and career progression in academia during times of uncertainty

While there is an extensive and still growing body of literature on women in academia and the challenges they encounter in career progression, there is little research on their experience specifically within a business school setting. In this study, we attempt to address this gap and examine the experiences and career development of female academics in a business school and how these are impacted by downsizing programmes. To this end, an exploratory case study is conducted. The findings of this study show that female business school academics experience numerous challenges in terms of promotion and development, networking, and the multiple and conflicting demands placed upon them. As a result, the lack of visibility seems to be a pertinent issue in terms of their career progression. Our data also demonstrates that that, paradoxically, during periods of downsizing women become more visible and thus vulnerable to layoffs as a consequence of the challenges and pressures created in their environment during this process. In this paper, we argue that this heightened visibility, and being subject to possible layoffs, further reproduces inequality regimes in academia.

Electricity derivatives pricing with forward-looking information

In order to increase overall transparency on key operational information, power transmission system operators publish an increasing amount of fundamental data, including forecasts of electricity demand and available capacity. We employ a fundamental model for electricity prices which lends itself well to integrating such forecasts, while retaining ease of implementation and tractability to allow for analytic derivatives pricing formulae. In an extensive futures pricing study, the pricing performance of our model is shown to further improve based on the inclusion of electricity demand and capacity forecasts, thus confirming the general importance of forward-looking information for electricity derivatives pricing. However, we also find that the usefulness of integrating forecast data into the pricing approach is primarily limited to those periods during which electricity prices are highly sensitive to demand or available capacity, whereas the impact is less visible when fuel prices are the primary underlying driver to prices instead.

The EarthCARE satellite: the next step forward in global measurements of clouds, aerosols, precipitation, and radiation

The collective representation within global models of aerosol, cloud, precipitation, and their radiative properties remains unsatisfactory. They constitute the largest source of uncertainty in predictions of climatic change and hamper the ability of numerical weather prediction models to forecast high-impact weather events. The joint European Space Agency (ESA)–Japan Aerospace Exploration Agency (JAXA) Earth Clouds, Aerosol and Radiation Explorer (EarthCARE) satellite mission, scheduled for launch in 2018, will help to resolve these weaknesses by providing global profiles of cloud, aerosol, precipitation, and associated radiative properties inferred from a combination of measurements made by its collocated active and passive sensors. EarthCARE will improve our understanding of cloud and aerosol processes by extending the invaluable dataset acquired by the A-Train satellites CloudSat, Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), and Aqua. Specifically, EarthCARE’s cloud profiling radar, with 7 dB more sensitivity than CloudSat, will detect more thin clouds and its Doppler capability will provide novel information on convection, precipitating ice particle, and raindrop fall speeds. EarthCARE’s 355-nm high-spectral-resolution lidar will measure directly and accurately cloud and aerosol extinction and optical depth. Combining this with backscatter and polarization information should lead to an unprecedented ability to identify aerosol type. The multispectral imager will provide a context for, and the ability to construct, the cloud and aerosol distribution in 3D domains around the narrow 2D retrieved cross section. The consistency of the retrievals will be assessed to within a target of ±10 W m–2 on the (10 km)2 scale by comparing the multiview broadband radiometer observations to the top-of-atmosphere fluxes estimated by 3D radiative transfer models acting on retrieved 3D domains.

Task design and interaction in collaborative writing: the students’ story

This article investigates student behaviour on collaborative assignments, looking at the relationship between task type and interaction, and considers the implications for task design. Students reported on interactions in a year-long workplace-focussed group communication project, comparing these with interactions on other academy based group assignments. Differences were seen in the amount of brainstorming, the criteria for dividing up work, the intensity of editing, and how conflict was managed. Contributing factors to these differences included the presence or absence of a creative element, the instrumental nature of the task, and the need for a collective approach inherent in the task design.

Health in Brazil 6 Health conditions and health-policy innovations in Brazil: the way forward

Brazil is a large complex country that is undergoing rapid economic, social, and environmental change In this Series of six articles, we have reported important improvements in health status and life expectancy, which can be ascribed largely to progress in social determinants of health and to implementation of a comprehensive national health system with strong social participation. Many challenges remain, however. Socioeconomic and regional disparities are still unacceptably large, reflecting the fact that much progress is still needed to improve basic living conditions for a large proportion of the population. New health problems arise as a result of urbanisation and social and environmental change, and some old health issues remain unabated. Administration of a complex, decentralised public-health system, in which a large share of services is contracted out to the private sector, together with many private insurance providers, inevitably causes conflict and contradiction. The challenge is ultimately political, and we conclude with a call for action that requires continuous engagement by Brazilian society as a whole in securing the right to health for all Brazilian people.

Looking for intrinsic charm in the forward region at BNL RHIC and CERN LHC

The complete understanding of the basic constituents of hadrons and the hadronic dynamics at high energies are two of the main challenges for the theory of strong interactions. In particular, the existence of intrinsic heavy quark components in the hadron wave function must be confirmed (or disproved). In this paper we propose a new mechanism for the production of D-mesons at forward rapidities based on the Color Glass Condensate (CGC) formalism and demonstrate that the resulting transverse momentum spectra are strongly dependent on the behavior of the charm distribution at large Bjorken x. Our results show clearly that the hypothesis of intrinsic charm can be tested in pp and p(d)A collisions at RHIC and LHC. (C) 2010 Elsevier B.V. All rights reserved.