Finite element modeling of lead acid batteries

This thesis investigates the finite element method with regard to the macrohomogeneous theory for flooded porous electrochemical cells, more specifically lead-acid cells. One- and two-dimensional finite element models are developed for flooded porous electrochemical lead acid cells. Chapter One introduces the background of the technology of lead-acid batteries, theory fundamentals, previous mathematical models for lead acid batteries, and the reason for the work. Chapter Two develops Newman’s macrohomogeneous equations for flooded porous electrodes. Chapter Three details the finite element theory, and how it is used to solve time dependent coupled non-linear partial differential equations. Chapter Four applies finite element theory to one-dimensional macrohomogeneous equations that describe lead-acid batteries. The results of the model are compared to previously published papers utilising finite difference methods. In Chapter Five, the technique is extend to two-dimensions and is validated with previously published papers of models on lead-acid batteries

An Interactive Graph Theory System

The medium of computer graphics provides a capability for dealing with pictures in man-machine communication. Graph Theory is used to model relationships which are represented by pictures and is therefore an appropriate discipline for the application of an interactive computer graphics system. Previous efforts to solve Graph Theoretic problems by computer have usually involved specialized programs written in a symbolic assembly language or algebraic compiler language. In recent years, graphics equipment with processing power has been commercially available for use as a remote terminal to a large central computer. Although these terminals typically include a small general purpose computer, the potential of using one as programmable subsystem has received little attention. These motivations have led to the design and implementation of an interactive graphics system for solving Graph Theoretic problems. The system operates on an IBM 7040 with a DEC-338 graphics terminal connected by voice-grade telephone line. To provide effective response times, computing power is appropriately divided between the two machines. The remote computer graphics terminal is controlled by a special-purpose executive program. This executive includes an interpreter of a command language oriented towards the control of existence and display of graphs. Several interactive functions such as graph drawing and editing are available to a user through light button and pushbutton selection. These functions which are local to the terminal are programmed in a mixture of the terminal computer\u27s machine language and the interpreted command language. For more significant computational requirements the central computer is used, but response time for interactive operation is then diminished. In order to overcome the speed of the telephone link, the central computer may call upon a program at the terminal as a subroutine. Based on the mathematical terminology used to define graphs, a high level language was developed for the specification of interactive algorithms. A growing library of these algorithms provides routines to aid in the construction and recognition of various types of graphs. Other routines are used for computing certain properties of graphs. Graphs may be transformed by some routines with respect to both connectivity and layout. Any number of graphs my be saved and later restored. A programmer using the terminal as an alphanumeric console may call upon the programming features of the system to develop new interactive algorithms and add them to the library. Programs may also be created for the display terminal, using the central computer for assembly. Examples of system use which are presented include finding a shortest path between any pair of vertices in a weighted directed graph, determining the maximally complete subgraphs of an arbitrary graph, interpreting a graph as a Mealy model of a finite state machine, and laying out a tree for aesthetic presentation

Publishing practices and the role of publication in the work of academics in the mathematics education research community in England

This thesis explores the publishing practices of the mathematics education research\ud community in England with the aim of better understanding the ways in which\ud education research is shaped by its social, institutional and political context. This is of\ud vital importance in debates about its goals, nature and future, particularly at a time of\ud rapid change in the higher education sector, with changing funding patterns, a drive for\ud research 'impact' and the association of publication with accountability through the\ud Research Assessment Exercise and the Research Excellence Framework.\ud Mathematics education research is explored on three levels: as a field, following\ud Bourdieu; through its external relations with other areas of research, with institutions,\ud government and society; and through the sense-making of individuals who are part of it.\ud The focus on publications cuts an analytical cross-section/seam across these three levels\ud since publication is intimately bound up in both internal and external struggles.\ud Interviews with academics and social network analysis of publication data are brought\ud together through an analysis of existing literature which examines the autonomy,\ud boundaries, entry conditions and doxa of mathematics education research as a field.\ud Semi-structured interviews with nine academics at English universities were used to\ud reconstruct some of the narrative resources drawn on in making sense of publishing\ud practices. These suggest that positive narratives around the value of publication to the\ud research field itself are lacking. This finding is I inked to the nature of education\ud research as a field of study connected to professional practice, as well as to the link\ud between publication and accountability. Exploratory social network analysis of\ud publication data from fourteen mathematics education research journals over a ten-year\ud period allowed a structural examination of the patterns that the ties formed by\ud collaboration. This analysis was then linked with interview data on individual\ud positioning within the field, suggesting the varied ways in which similar patterns of\ud collaboration arise.\ud Implications are drawn for mathematics education research in the UK and for the role of\ud publication in social sciences research, particularly in a field of study connected with\ud professional practice

Seeing the bigger picture: visual imagination and the social brain

I studied multi-modal aspects of visual imagination in relation to visual art and complex images, defining ‘visual imagination’ broadly as a dynamic of complex psychological processes that integrate visual information with prior experiences and knowledge to construct internal models of oneself, others and the outside world. This reflects the ultimate aim of my work to develop engaging cultural and clinical resources that strengthen social brain networks, tailored to personal interests, age and cognitive health. I pursued two interrelated research programmes based primarily at the Wellcome Collection, as part of my interdisciplinary residency with Created Out of Mind. I used complementary neuroscientific and visual research methods to probe relationships between visual imagination and the social brain in neurologically healthy adults and people living with various forms of dementia. The Social Brain Atlas and connectome (Alcalá López et al., Cerebral Cortex 2017) was recently computed from 3972 functional neuroimaging studies in 22712 healthy adults: to contextualise my research in the social brain, I first translated the social brain connectome to functional infographics (relational spatial representations) of the four hierarchical processing levels of the Social Brain Atlas, and generated visual imagination brain profiles in healthy adults and profiles of canonical dementia syndromes. I used these to generate hypotheses and guide analysis of my neuroscientific experiments. I recruited three participant cohorts: 17 neurologically healthy adults aged 20-30 years; 20 neurologically healthy adults aged 50+ years; and 11 senior adults living with various forms of dementia. These research participants took part in five neuroscientific experiments that I had designed, in which I used advanced technologies to capture physiological responses and established as well as novel visual research methods to study neuropsychological responses to visual art, complex imagery and colour experiences. I employed an arts-based facilitated conversation methodology, Visual Thinking Strategies (VTS); and I developed novel quantitative methods to analyse recorded eye tracking data, electrodermal activity and speech samples. I used both parametric and non-parametric statistical methods to compare participant cohorts. In parallel with the neuroscientific research, I developed a series of art experiments at UCL Institute of Making, and my studio at the Limehouse Art Foundation, East London. My artistic research complemented my neuroscientific work by emphasising individual experience over generic perceptual mechanisms: by creating space for personal interactions with art, the research becomes contextualised in the social world. The artistic research resulted in a public exhibition of optical instruments, visual artworks and installations that expanded on the two neuroscientific research projects, complementing the written thesis with the embodied language of visual art. Visitors could freely explore the perceptual effects of the optical instruments and were invited to reflect on the visual artworks with the Visual Thinking Strategies method

A cognitive model of fiction writing.

Models of the writing process are used to design software tools for writers who work with computers. This thesis is concerned with the construction of a model of fiction writing. The first stage in this construction is to review existing models of writing. Models of writing used in software design and writing research include behavioural, cognitive and linguistic varieties. The arguments of this thesis are, firstly, that current models do not provide an adequate basis for designing software tools for fiction writers. Secondly, research into writing is often based on questionable assumptions concerning language and linguistics, the interpretation of empirical research, and the development of cognitive models. It is argued that Saussure's linguistics provides an alternative basis for developing a model of fiction writing, and that Barthes' method of textual analysis provides insight into the ways in which readers and writers create meanings. The result of reviewing current models of writing is a basic model of writing, consisting of a cycle of three activities - thinking, writing, and reading. The next stage is to develop this basic model into a model of fiction writing by using narratology, textual analysis, and cognitive psychology to identify the kinds of thinking processes that create fictional texts. Remembering and imagining events and scenes are identified as basic processes in fiction writing; in cognitive terms, events are verbal representations, while scenes are visual representations. Syntax is identified as another distinct object of thought, to which the processes of remembering and imagining also apply. Genette's notion of focus in his analysis of text types is used to describe the role of characters in the writer's imagination: focusing the imagination is a process in which a writer imagines she is someone else, and it is shown how this process applies to events, scenes, and syntax. It is argued that a writer's story memory, influences his remembering and imagining; Todorov's work on symbolism is used to argue that interpretation plays the role in fiction writing of binding together these two processes. The role of naming in reading and its relation to problem solving is compared with its role in writing, and names or signifiers are added to the objects of thought in fiction writing. It is argued that problem solving in fiction writing is sometimes concerned with creating problems or mysteries for the reader, and it is shown how this process applies to events, scenes, signifiers and syntax. All these findings are presented in the form of a cognitive model of fiction writing. The question of testing is discussed, and the use of the model in designing software tools is illustrated by the description of a hypertextual aid for fiction writers