Effect of composition and austenite deformation on the transformation characteristics of low-carbon and ultralow-carbon microalloyed steels

Deformation dilatometry has been used to simulate controlled hot rolling followed by controlled cooling of a group of low- and ultralow-carbon microalloyed steels containing additions of boron and/or molybdenum to enhance hardenability. Each alloy was subjected to simulated recrystallization and nonrecrystallization rolling schedules, followed by controlled cooling at rates from 0.1 °C/s to about 100 °C/s, and the corresponding continuous-cooling-transformation (CCT) diagrams were constructed. The resultant microstructures ranged from polygonal ferrite (PF) for combinations of slow cooling rates and low alloying element contents, through to bainitic ferrite accompanied by martensite for fast cooling rates and high concentrations of alloying elements. Combined additions of boron and molybdenum were found to be most effective in increasing steel hardenability, while boron was significantly more effective than molybdenum as a single addition, especially at the ultralow carbon content. Severe plastic deformation of the parent austenite (>0.45) markedly enhanced PF formation in those steels in which this microstructural constituent was formed, indicating a significant effective decrease in their hardenability. In contrast, in those steels in which only nonequilibrium ferrite microstructures were formed, the decreases in hardenability were relatively small, reflecting the lack of sensitivity to strain in the austenite of those microstructural constituents forming in the absence of PF.

Linking the macroscopic and sub-microscopic levels : diagrams

Explanations of chemical phenomena are nearly always focused at the sub-micro level, a level that cannot be observed, yet are normally provided with diagrams at the symbolic level. These diagrams represent the macro and sub-micro levels of matter. The connections between the macro level and the diagrams of the sub-micro level are not always apparent to students, indicating a need for chemical diagrams to be used carefully and explicitly. Having students draw and annotate chemical diagrams representing chemical phenomena at the sub-micro level can provide some insight into their understanding of chemistry at the macro level. Misinterpretation of diagrams can occur when the representations are not understood, when links are not made between the macro and sub-micro levels, or when the diagram is unfamiliar. Responding to these difficulties, strategies based on research and our experiences of teaching with diagrams are suggested for the choice and use of chemical diagrams depicting the sub-micro level in the teaching and learning of chemistry. These strategies provide opportunities for learners to construct acceptable personal mental models of the sub-micro level.

Student-generated submicro diagrams : a useful tool for teaching and learning chemical equations and stoichiometry

This paper reports on a pedagogical approach to the teaching of chemical equations introduced to first year university students with little previous chemical knowledge. During the instruction period students had to interpret and construct diagrams of reactions at the submicro level, and relate them to chemical equations at the symbolic level with the aim of improving their conceptual understanding of chemical equations and stoichiometry. Students received instruction in symbol conventions, practice through graded tutorial tasks, and feedback on their efforts over the semester. Analysis of the student responses to formative test and summative exam items over consecutive years indicates that there was a consistent improvement in the abilities of the various cohorts to answer stoichiometry questions correctly. The responses provide evidence for diagrams of the submicro level being used as tools for reasoning in solving chemical problems, to recognise misconceptions of chemical formulae and to recognise the value of using various multiple representations of chemical reactions connecting the submicro and symbolic levels of representation. The student-generated submicro diagrams serve as a visualisation tool for teaching and learning abstract concepts in solving stoichiometric problems. We argue that the use of diagrams of the submicro level provides a more complete picture of the reaction, rather than a net summary of a chemical equation, leading to a deeper conceptual understanding.

The effect of simulated thermomechanical processing on the transformation behavior and microstructure of a low-carbon Mo-Nb linepipe steel

The present work investigates the transformation behavior of a low-carbon Mo-Nb linepipe steel and the corresponding transformation product microstructures using deformation dilatometry. The continuous cooling transformation (CCT) diagrams have been constructed for both the fully recrystallized austenite and that deformed in uniaxial compression at 1148 K (875 °C) to a strain of 0.5 for cooling rates ranging from 0.1 to about 100 K/s. The obtained microstructures have been studied in detail using electron backscattered diffraction complemented by transmission electron microscopy. Heavy deformation of the parent austenite has caused a significant expansion of the polygonal ferrite transformation field in the CCT diagram, as well as a shift in the non-equilibrium ferrite transformation fields toward higher cooling rates. Furthermore, the austenite deformation has resulted in a pronounced refinement in both the effective grain (sheaf/packet) size and substructure unit size of the non-equilibrium ferrite microstructures. The optimum microstructure expected to display an excellent balance between strength and toughness is a mix of quasi-polygonal ferrite and granular bainite (often termed “acicular ferrite”) produced from the heavily deformed austenite within a processing window covering the cooling rates from about 10 to about 100 K/s.

Geometry and combinatorics of the cutting angle method

Lower approximation of Lipschitz functions plays an important role in deterministic global optimization. This article examines in detail the lower piecewise linear approximation which arises in the cutting angle method. All its local minima can be explicitly enumerated, and a special data structure was designed to process them very efficiently, improving previous results by several orders of magnitude. Further, some geometrical properties of the lower approximation have been studied, and regions on which this function is linear have been identified explicitly. Connection to a special distance function and Voronoi diagrams was established. An application of these results is a black-box multivariate random number generator, based on acceptance-rejection approach.

Monitoring ecological impacts: concepts and practice in flowing waters

Monitoring Ecological Impacts provides the tools needed to design  assessment programs that can reliably monitor, detect and allow  management of human impacts on the natural environment. The procedures described are well-grounded in inferential logic. Step-by-step guidelines and flow diagrams provide clear and useable protocols, which are applicable to real situations.

Ionic liquid mixtures—variations in physical properties and their origins in molecular structure

In order to explore the various possible property trends in ionic liquid mixtures, five different ionic liquids were mixed with N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([C₃mpyr][NTf₂]), and the viscosities, excess molar volumes, ionic conductivities, and phase diagrams of the mixtures were determined over a range of temperatures. In a number of the mixtures the crystallization of both components was completely suppressed and no melting point was observable. Such mixtures of similar ionic liquids thus have potential for use in low-temperature applications by extending the liquid range to T_g. The molar conductivities and viscosities are described as approximating predictable or “simple” mixing behaviors, while excess molar volumes were found to show a variety of mixing and nonideal mixing effects. Mixture equations for viscosity and conductivity are discussed and analyzed. An immiscibility window was observed in the trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)amide ([P_6,6,6,14][NTf₂]) in the [C₃mpyr][NTf₂] system in the [C₃mpyr][NTf₂]-rich region. Unusual physical properties are exhibited by miscible compositions near the demixing line. These compositions are described as [P_6,6,6,14][NTf₂]-like, even up to 0.5 mol fraction of [C₃mpyr][NTf₂].

A suite of visual languages for model-driven development of statistical surveys and services

Objective: To provide statistician end users with a visual language environment for complex statistical survey design and implementation. Methods: We have developed, in conjunction with professional statisticians, the Statistical Design Language (SDL), an integrated suite of visual languages aimed at supporting the process of designing statistical surveys, and its support environment, SDLTool. SDL comprises five diagrammatic notations: survey diagrams, data diagrams, technique diagrams, task diagrams and process diagrams. SDLTool provides an integrated environment supporting design, coordination, execution, sharing and publication of complex statistical survey techniques as web services. SDLTool allows association of model components with survey artefacts, including data sets, metadata, and statistical package analysis scripts, with the ability to execute elements of the survey design model to implement survey analysis. Results: We describe three evaluations of SDL and SDLTool: use of the notation by expert statistician to design and execute surveys; useability evaluation of the environment; and assessment of several generated statistical analysis web services. Conclusion: We have shown the effectiveness of SDLTool for supporting statistical survey design and implementation. Practice implications: We have developed a more effective approach to supporting statisticians in their survey design work.

Futures in education

Futures education (FE) in a rapidly changing world is critical if young people are to be empowered to be proactive rather than reactive about the future. Research into young people's images and ideas of the future lead to the disturbing conclusion that, for many, the future is a depressing and fearful place where they feel hopeless and disempowered. On the other hand, as Richard Slaughter writes, 'young people are passionately interested in their own futures, and that of the society in which they live. They universally 'jump at the chance to study something with such intrinsic interest that also intersects with their own life interests in so many ways'. FE explicitly attempts to build on this interest and counter these fears by offering a profound and empowering set of learning strategies and ideas that can help people think and act critically and creatively about the future, without necessarily trying to predict it. Futures educators have, over the past decades, developed useful tools, ideas and a language for use with students of all ages to enable them to develop foresight literacy. Most of us tend to view the future as somehow beyond the present and rarely consider how decisions and choices made today profoundly affect not just one fixed future but any number of futures. The underlying goal of FE is to move from the idea of a single, pre-determined future to that of many possible futures, so that students begin to see that they can determine the future, that they need not be reactive and that they are not powerless. How does one do that? Ideas include, but are not limited to: timelines and Y-diagrams, futures wheels and mind maps, and 'Preferable, possible and probable' futures - a.k.a. the 3Ps. Current Australian curricula present education about the future in various implicit or explicit guises. A plethora of statements and curriculum outcomes mention the future, but essentially take 'it' for granted, and are uninformed by FE literature, language, ideas or tools. Science, the humanities and technology tend to be the main areas where such an implicit futures focus can be found. It also appears in documents about vocational education, civics and lifelong learning. Explicit FE is, as Beare and Slaughter put it, still the missing dimension in education. Explicit FE attempts to develop futures literacy, and draws widely upon futures studies literature for processes and content. FE provides such a wide range of ideas and tools that it can be incorporated into education in any number of ways. Programs in two very different schools, one primary and one secondary, are described in this article to provide examples of some of these ways. The first school, Kimberley Park State Primary School in Brisbane, operates with multi-age classrooms based on a 'thinking curriculum' developed around four organisers: change, perspectives, interconnectedness and sustainability. The second school, St John's Grammar School in Adelaide, is an independent school where FE operates as an integrated approach in Year Seven, as a separate one-semester subject in Year Nine and in separate subjects at other levels. Teachers both at Kimberley Park and St John's are very positive about FE. They say it promotes valuable and authentic learning, assists students to realise they have choices that matter and helps them see that the future need not be all doom and gloom. Because students are interested in the Big Questions, as one teacher put it, FE provides a perfect opportunity to address them, and to consider values that are fundamental for them and the future of the planet. Like any innovation, the long-term success of FE in schools depends on an embedding process so that the innovation does not depend on the enthusiasm and energy of a few individuals, only to disappear when they move on. It requires strong leadership, teacher knowledge, support and enthusiasm, and the support and understanding of the wider school community.

The descriptive and explanatory nature of chemical diagrams does not guarantee understanding

Volunteer non-major chemistry students, taking an introductory university chemistry course (n= 17) were interviewed about their understanding of a variety of chemical diagrams. All the students’ interviewed appreciated that diagrams of laboratory equipment were useful to show how to set up laboratory equipment. However students’ ability to explain specific diagrams at either the macroscopic or sub-microscopic level varied greatly. The results highlighted the poor level of understanding that some students had even after completing both exercises and experiments using the diagrams. The connection between the diagrams of the macroscopic level (equipment), the sub-microscopic level (molecular) and the symbolic level (equations) was not always apparent to students. The results indicate a need for chemical diagrams to be used carefully and more explicitly to ensure the learner understanding.

Using data mining for digital ink recognition: dividing text and shapes in sketched diagrams

The low accuracy rates of textshape dividers for digital ink diagrams are hindering their use in real world applications. While recognition of handwriting is well advanced and there have been many recognition approaches proposed for hand drawn sketches, there has been less attention on the division of text and drawing ink. Feature based recognition is a common approach for textshape division. However, the choice of features and algorithms are critical to the success of the recognition. We propose the use of data mining techniques to build more accurate textshape dividers. A comparative study is used to systematically identify the algorithms best suited for the specific problem. We have generated dividers using data mining with diagrams from three domains and a comprehensive ink feature library. The extensive evaluation on diagrams from six different domains has shown that our resulting dividers, using LADTree and LogitBoost, are significantly more accurate than three existing dividers.

Rethinking schools and community : the knowledge producing school

Schools appear in some accounts of community informatics as part of community, one of a number of organisations that need to be taken into account, perhaps on the basis of them being useful physical or human resources around which community informatics might be based. For their part, schools, at least in Australia, have been an important, early element in the broad take-up of computing and communication technologies (CCTs) by the community. Apart from the possibility of using school resources to support community access out of school time and based on what is published in both fields, schools and work in community informatics have tended to operate independently of one another. There are, nonetheless, interesting parallels in these two broad areas of activity which promote the use of CCTs. This chapter outlines a new research agenda in which schools produce knowledge for local community and in doing so develop new and productive community partnerships. The development provides interesting opportunities for the transformation of regions via this approach to community informatics. The background to this project is based in the long history of using CCTs in schools. The chapter will argue that the way in which schools understand CCTs is crucial to shaping what is possible to be done with CCTs in schools. Shifting the emphasis from information to relationships opens up alternatives that provide opportunities for significant, new relationships with community.

Achieving greater feedback and flexibility using online pre-laboratory exercises with non-major chemistry students

Compulsory online pre-laboratory exercises were required of non-major, first-year university chemistry students in response to poor student preparation for laboratory sessions. The online pre-laboratory exercises were designed to be straightforward, endeavoring to help students maximize the benefits of the introductory laboratory class. Diagrams and pictures were included in the exercises to improve descriptions. Students were allowed multiple attempts with immediate feedback provided to help them learn from their mistakes. The study is a descriptive account of students' perceptions of the impact of online pre-laboratory exercises on their learning. Students recognized the value of the exercises in improving their organization, their preparedness for the laboratory class, and their understanding of the chemistry concepts of the weekly experiments. The increased flexibility of doing pre-laboratory exercises online and the increased feedback to students were two important aspects of this project that nearly all students recognized as being beneficial to their learning.

Correct interpretation of chemical diagrams requires transforming from one level of representation to another

17 volunteer non-major chemistry students taking an introductory university chemistry course were interviewed about their understanding of a variety of chemical diagrams. All the students' interviewed appreciated that diagrams of laboratory equipment were useful to show how to set up laboratory equipment. However students' ability to explain specific diagrams at either the macroscopic or sub-microscopic level varied greatly. The results highlighted the poor level of understanding that some students had even after completing both exercises and experiments using the diagrams. The connection between the diagrams of the macroscopic level (equipment, chemicals), the sub- microscopic level (molecular) and the symbolic level (equations) was not always considered explicitly by students. The results indicate a need for chemical diagrams to be used carefully and more explicitly to ensure learner understanding. Correspondingly, students need to interpret visual chemical diagrams using meta-visualisation skills linking the various levels of representation, and appreciating the role of the diagrams in explanations need to be developed.