Evolution of Langmuir waves in a plasma contaminated by variable-charge impurities

The propagation of Langmuir waves in nonisothermal plasmas contaminated by fine dust particles with variable charge is investigated for a self-consistent closed system. Dust charge relaxation, ionization, recombination, and collisional dissipation are taken into account. It is shown that the otherwise unstable coupling of the Langmuir and dust-charge relaxation modes becomes stable and the Langmuir waves are frequency down-shifted.

Low-frequency dispersion properties of plasmas with variable-charge impurities

A theory of low-frequency dust-acoustic waves in low-temperature collisional plasmas containing variable-charge impurities is presented. Physical processes such as dust-charge relaxation, ionization-recombination of the electrons and ions, electron and ion elastic collisions with neutrals and dusts, as well as charging collisions with the dusts, are taken into account. Inclusion of these processes allows a balance of the plasma particles and thus a self-consistent determination of the stationary state of the unperturbed plasma. The generalized dispersion relation describing the propagation and damping of the dust acoustic waves is derived and analyzed. © 2000 American Institute of Physics.

Networking iPads into Preschool Spaces

This chapter explores preschools as networked spaces into which iPads were introduced, which involved the mediation of complex relationships between children and adults, physical and virtual technology and other materials like toys, play spaces, art materials and books. The chapter aims to explain how these human and non-human ‘actors’ come to coexist and lead to the development of literacy and creativity in specific ways. This approach particularly draws attention to specific challenges faced by the teachers as they negotiated a range of complex demands and obstacles to make the iPads available to the children for play and learning.

Art spaces in community and economic development : connections to neighborhoods, artists, and the cultural economy

There is growing interest in the arts in community and economic development, yet little research examines the dynamics of community-based arts institutions to inform urban planning and policy. Drawing on interviews with participants and organizers of small and midsized art spaces, the study explores the factors that influence their involvement in neighborhood revitalization and outreach, support for artistic communities, and efforts to build bridges to commercial cultural sectors. Art spaces function as a conduit for building social networks that contribute to both community revitalization and artistic development. But issues pertaining to the location, organization, and management of art spaces may limit their community and economic development potential. The article concludes with proposals to craft stronger arts-based community and economic development programs.

Art spaces, public space, and the link to community development

Recent literature credits community art spaces with both enhancing social interaction and engagement and generating economic revitalization. This article argues that the ability of art spaces to realize these outcomes is linked to their role as public spaces and that their community development potential can be expanded with greater attention to this role. An analysis of the public space characteristics is useful because it encourages consideration of sometimes overlooked issues, particularly the effect of the physical environment on outcomes related to community development. I examine the relationship between public space and community development at various types of art spaces including artist cooperatives, ethnic-specific art spaces, and city-sponsored art centers in central city and suburban locations. This study shows that through their programming and other activities, art spaces serve various public space roles related to community development. However, the ability of many to perform as public spaces is hindered by facility design issues and poor physical connections in their surrounding area. This article concludes with proposals for enhancing the community development role of the art spaces through their function as public spaces.

Designing schools as effective 21st C learning spaces : a review

The Queensland Centre for Social Science Innovation was formed in 2012 to develop collaborations among the Queensland Government and five Queensland universities—The University of Queensland, Griffith University, Queensland University of Technology, James Cook University and Central Queensland University. Three priorities for initial projects were established by the Queensland Government with response by the participating universities. This project addressed the identified priority area: factors affecting educational achievement and investigation of the link between school design, refurbishment and educational outcomes. The proposal for this project indicated that a Review of research literature would be undertaken that linked school and classroom design with educational outcomes for learners in the 21st century. Further, research would be examined for impact of technology on staff and students, as well as learning spaces that addressed the diversity of student learners. Specific investigation of research on effective design to enhance learning outcomes for Aboriginal and Torres Strait Islander students was to be undertaken. The project therefore consists of a Review of research literature to provide an evidence base on the impact of school and classroom on educational outcomes. The original proposal indicated that indicators of successful school and classroom design would be student learning outcomes on a range of variables, with input, the specific architectural design elements. The review was undertaken during the period July 2012 to June 2013. A search was undertaken of journals, databases, and websources to identify relevant material. These were examined for evidence-based statements and design of learning spaces to enhance learning. The Review is comprehensive, and representative of issues raised in research, and conceptualisations and debates informing modern educational design. Initial findings indicated two key findings central to reading this Review. The first key finding is that the predominant focus of modern design of learning space is on process and the engagement of stakeholders. Schools are social institutions and development of a school as a learning space to suit 21st century learning needs necessarily involves the staff, students and other members of the community as key participants. The concept of social aspects of design is threaded throughout the Review. The second key finding is that little research explicitly examined the relationship between the design of learning spaces and educational outcomes. While some research does exist, the most explicitly-focused research uses narrow test-based achievement as the learning outcomes. These are not sympathetic to the overall framings of the research on 21st century learning, future schooling and the needs of the new generation of learners and society.

Art Spaces, Art Places : Examining Neighborhood Preferences of New York Arts Organizations

This report builds on and extends a diverse literature that examines the location patterns of the arts and creative industries through analysis of a database of arts nonprofit organizations from the New York State Cultural Data Project. We confirm the link between arts organizations and the urban core and creative economy, but challenge the assumption that arts tend to locate in ethnic and disadvantaged neighborhoods. By identifying key neighborhood attributes associated with distinct types of arts organizations, we can better identify potential sites conducive to nurturing additional artistic activity and inform strategies to engage organizations in neighborhoods that are underserved in the arts.

The Habitual Rhythms of Becoming-Involved: Insights into Participation Experiences in Urban Spaces by Children with Diverse Mobility

This chapter reports on a study that reveals the essence of participation in urban spaces by ten children who live with various physical conditions: Muscular Dystrophy, Cerebral Palsy, and Autoimmune Rheumatic Diseases. These conditions affect muscle and movement differently resulting in diverse ways in which children move through space (personal mobility). The children at the time of the research were 9-12 years of age residing in South-east Queensland, Australia. The approach and methods selected for this study, interpretive phenomenological inquiry and grounded theory, were chosen for their capacity to capture the complexity and multiple interactions of the child’s urban living. The confronting and poignant accounts by children and their families of their experiences produced a new way of understanding the concept of participation, as a ‘journey of becoming involved.’ Their accounts of performing everyday routines (e.g. leaving home, getting in and out of the car, and entering places) in urban spaces (neighbourhood streets, schools, open spaces, shopping centres, and hospitals) revealed differences in the way settings were experienced. These differences were associated with the interplay between the body, space and context. Where interplays were problematic, explicit decisions about children’s involvement were made. These decisions were described in terms of ‘avoid going’, ‘pick and choose’, ‘discontinue’, ‘accept’, or ‘contest.’ What these decisions mean is some spaces are avoided, some journeys are discontinued, and some barriers encountered in journeys are normalised as everyday experiences, i.e. ‘tolerable discrimination’. These actions resulted in experiences of non-participation or partial–tokenistic participation. The key substantive contribution of the research lies in the identification of points in children’s journeys that shape participation experience. These points identify where future interventions in policy, programming and design can be made to make real and sustaining changes to lives of children and their families in geographies crucial to urban living.

Rectifier systems for variable speed wind generation : a review

The drive towards high efficiency wind energy conversion systems has resulted in almost all the modern wind turbines to operate in the variable speed mode which inevitably requires back-to-back power electronic converters to decouple generator dynamics from the grid. The aim of this paper is to present an analysis on suitable topologies for the generator-side converter (rectifier) of the back-to-back converter arrangement. Performance of the two most popular rectifier systems, namely, the passive diode bridge rectifier and the active six-switch two-level rectifier are taken as two extremes to evaluate other topologies presented in this paper. The other rectifier systems considered in this study include combinations of a diode bridge rectifier and electronic reactance(s), a combination of a rectifier and a dc-dc converter and a half controlled rectifier. Diode-clamped and capacitor-clamped three-level active rectifier topologies and their possible switch reductions are also discussed in relation to the requirements of modern high power wind energy conversion systems (WECSs). Simulation results are presented to support conclusion derived from this analysis.

Controller design for variable-speed permanent magnet wind turbine generators interfaced with Z-source inverter

Increased awareness of environmental concerns has caused greater interest in developing power sources based on renewable technologies, such as wind. Due to the intermittent nature of the wind speed, output voltage and frequency of the direct driven permanent magnet synchronous generators (PMSG) are normally unsteady. Recently proposed Z-source inverter has been considered as a potential solution for grid interfacing wind power generators, thanks to buck-boost function that the single stage Z-source inverter can offer. Two control methodologies, namely unified controller for isolated operation and a multi-loop controller for grid interfaced operation are investigated in this paper. Theoretical analysis of these two control schemes is presented and experimental results to verify the effectiveness of the control method are also included.

Z-source converter based grid-interface for variable-speed permanent magnet wind turbine generators

A Z-source inverter based grid-interface for a variable-speed wind turbine connected to a permanent magnet synchronous generator is proposed. A control system is designed to harvest maximum wind energy under varied wind conditions with the use of the permanent magnet synchronous generator, diode-rectifier and Z-source inverter. Control systems for speed regulation of the generator and for DC- and AC- sides of the Z-source inverter are investigated using computer simulations and laboratory experiments. Simulation and experimental results verify the efficacy of the proposed approach.

Engaging children and young people in creating resilient and healthy urban spaces

Urban public space in Australia and internationally, can be critically examined from a number of multidisciplinary standpoints, including human geography, urban design, planning, sociology, and public health. Viewing urban public space from a range of perspectives encourages different vantage points to emerge and questions around health, wellbeing and public space are increasingly topical and important in the broadest of terms, with public space being a key arena for physical activity, mental health, commercial, cultural and community life and the possibility of social inclusion. However, in the name of urban regeneration, programs of securitisation, ‘gentrification’ ‘creative’ and ‘smart’ city initiatives refashion public space as sites of selective inclusion and exclusion (Watson 2005; Gabrys 2014). In this context of monitoring and control procedures, in particular, children and young people’s use of space in parks, neighbourhoods, shopping malls and streets, is often viewed as a threat to social order, requiring various forms of remedial action, such as being ‘designed out’ of public space (Johnson 2014). Rarely are children and young people actively and respectfully brought into planning and governance processes and consequently many urban public spaces are essentially adult places, where control and ongoing surveillance are the key concerns (Freeman 2011, Dee 2013). There is also a political economy of public space discernable in cities like Brisbane, where ‘flagship’ infrastructure such as road tunnels take pride of place, while more humbly appointed pedestrian footpaths are often narrow, in a poor state of repair and a potential barrier to good health (Atkinson and Easthope 2009). The recent development of bikeways in Brisbane is a case in point, presenting both challenges and opportunities in being a valuable new form of public space heavily used by ‘commuter cyclists’ by day, but poorly lit and conceived, for a range of users at other times (Wyeth 2014). This paper concentrates on questions of social citizenship rights and discourses of health and wellbeing and suggests that cities, places and spaces and those who seek to use them, can be resilient in maintaining and extending democratic freedoms, calling surveillance, planning and governance systems to account (Smith 2014). The active inclusion of children and young people better informs the implementation of public policy around the design, build and governance of public space and also understandings of urban citizenship, leading to healthier, more inclusive, public space for all (Jacobs 1965).

The Journey of Becoming Involved in Urban Spaces by Children with Diverse Mobility

Participation is a word frequently espoused in the literature of childhood and urban studies. It has also been made sacrosanct through the Convention on the Rights of the Child and other rights-based policy and programming. Despite this importance, what it means and how it is experienced in the everyday lives of children with diverse abilities is not well understood. This chapter provides insight into the everyday experiences of participation by ten children 9-12 years of age, who have diverse personal mobility from various physical conditions that affect muscle and movement differently, including: Muscular Dystrophy, Cerebral Palsy, and Autoimmune Rheumatic Diseases. The children participants live in the outer suburbs and inner regions of south-east Queensland, Australia. The chapter discusses a new way of understanding and theorising participation as a journey of becoming involved. This knowledge emerged through the children’s body-space-time routines (body ballets) and their descriptions of inhabiting urban space. This chapter also establishes how body-space-context interplays shape the experiences of becoming and being involved in everyday life, as well as the preconceptions of body embed in space which divide and constrain children and families actualisation of full and genuine participation.

On the effect of topology on cellular automata rule spaces

This thesis presents an empirical study of the effects of topology on cellular automata rule spaces. The classical definition of a cellular automaton is restricted to that of a regular lattice, often with periodic boundary conditions. This definition is extended to allow for arbitrary topologies. The dynamics of cellular automata within the triangular tessellation were analysed when transformed to 2-manifolds of topological genus 0, genus 1 and genus 2. Cellular automata dynamics were analysed from a statistical mechanics perspective. The sample sizes required to obtain accurate entropy calculations were determined by an entropy error analysis which observed the error in the computed entropy against increasing sample sizes. Each cellular automata rule space was sampled repeatedly and the selected cellular automata were simulated over many thousands of trials for each topology. This resulted in an entropy distribution for each rule space. The computed entropy distributions are indicative of the cellular automata dynamical class distribution. Through the comparison of these dynamical class distributions using the E-statistic, it was identified that such topological changes cause these distributions to alter. This is a significant result which implies that both global structure and local dynamics play a important role in defining long term behaviour of cellular automata.