Isovists, occlusions and the exosomatic visual architecture

Recently, simulation agents (or animats) using an exosomaticvisual architecture (EVA) have been shown to correlate well with ob-served pedestrian movement in both building and urban environments.An EVA uses a grid overlaid on a two-dimensional plan of a system torecord the locations visible from the current grid square. The agents areallowed to roam freely in the environment, and lookup visual informationfrom the EVA in order to guide them through the plan. This allows manyagents to navigate concurrently using visibility relationships. However,while good correlation between observed physical and virtual systemshas been shown, experiments to date have been based on agents whichmove stochastically to visible locations. This leads to them congregatingin large open vistas, where there are more visible locations. In contrast,when people are observed, they tend to follow the edges of spaces tomove or take direct routes across open spaces to the far side. Here wehypothesize that rather than using open space to guide them, people in-stead use the visual clue of an occluding edge to indicate where furthermovement potential may lie. We supplement the information in the EVAwith details of the isovist at each location, to supply the locations ofoccluding edges from each grid square. We show that these new agentsfollow paths much more similar to observed pedestrians using an openspace. We speculate that the invariance of the occlusion points within aplan may thus lead to an economic skeletal mapping of the environment,and possible basis for a cognitive map

Analysing the visual dynamics of spatial morphology

Recently there has been a revival of interest in visibility analysis of architectural configurations. The new analyses rely heavily on computing power and statistical analysis, two factors which, according to the postpositivist school of geography, should immediately cause us to be wary. Thedanger, they would suggest, is in the application of a reductionist formal mathematical description in order to `explain' multilayered sociospatial phenomena. The author presents an attempt to rationalise how we can use visibility analysis to explore architecture in this multilayered context by considering the dynamics that lead to the visual experience. In particular, it is recommended that we assess the visualprocess of inhabitation, rather than assess the visibility in vacuo. In order to investigate the possibilities and limitations of the methodology, an urban environment is analysed by means of an agent-based model of visual actors within the configuration. The results obtained from the model are compared with actual pedestrian movement and other analytic measurements of the area: the agents correlate well both with human movement patterns and with configurational relationship as analysed by space-syntax methods. The application of both methods in combination improves on the correlation with observed movement of either, which in turn implies that an understanding of both the process of inhabitation and the principles of configuration may play a crucial role in determining the social usage of space

Encoding natural movement as an agent-based system: an investigation into human pedestrian behaviour in the built environment

Gibson's ecological theory of perception has received considerable attention within psychology literature, as well as in computer vision and robotics. However, few have applied Gibson's approach to agent-based models of human movement, because the ecological theory requires that individuals have a vision-based mental model of the world, and for large numbers of agents this becomes extremely expensive computationally. Thus, within current pedestrian models, path evaluation is based on calibration from observed data or on sophisticated but deterministic route-choice mechanisms; there is little open-ended behavioural modelling of human-movement patterns. One solution which allows individuals rapid concurrent access to the visual information within an environment is an 'exosomatic visual architecture" where the connections between mutually visible locations within a configuration are prestored in a lookup table. Here we demonstrate that, with the aid of an exosomatic visual architecture, it is possible to develop behavioural models in which movement rules originating from Gibson's principle of affordance are utilised. We apply large numbers of agents programmed with these rules to a built-environment example and show that, by varying parameters such as destination selection, field of view, and steps taken between decision points, it is possible to generate aggregate movement levels very similar to those found in an actual building context

Farm Tenancy Distribution and Trends in the United States

This paper includes a study of the mutual fund market investors during a selected time period. The reader is given a descriptive picture of how people in different age groups have  acted  in  conjunction  with  the  last  major  financial  crisis.  It  has  been  studied whether people in the different age categories have saved, purchased or sold during this time  period  based  on  theories  and  analytic  material  from  one  of  the  largest  fund operators in Sweden. The result enlightens people’s activity and risk appetite in relation to the fund market. The essay results in an explanation of the underlying cause of the behavior        of         the         people         in         the         different         age         categories. The paper assumes that the market is cyclical and that more crises will occur in the future. The most recent crisis developed during the years 2007-2008 and has therefore been  selected  to  represent  the  analyzed  period.  Among  other  things,  a  general hypothesis  was  applicable  to  recurring  tendency  of  nonprofessional  retail  client  in extreme market situations to buy fund shares at a high value and sell them at low value in the market. The starting point was to criticize this hypothesis, which clearly turned out   to   be   in   favor   for   one   of   the   mutual   funds   that   have   been   observed. The result shows that more people in the middle age save more than those in their young years as well as those in the retirement age. The conclusion of the study shows that when this crisis occurred there were no major withdrawals from any of the mutual funds. In fact the sales transaction was reduced in the period of time from the peak of the stock market in 2007 to the time market touched the ground in 2008.I denna uppsats undersöks fondmarknadens investerare under en vald tidsperiod. Läsaren ges en beskrivande bild av hur personer i olika ålderskategorier har agerat i samband med den senaste stora finanskrisen. Det har studerats, med stöd av teorier och analysmaterial från en av Sveriges största fondaktörer, huruvida personer i de olika ålderskategorierna har sparat under denna period. Resultatet belyser personers aktivitet och riskbenägenhet i förhållande till fondmarknaden. Uppsatsen mynnar ut i en förklaring till vad som är och kan vara bakomliggande orsaker till beteendet hos personerna i de olika ålderskategorierna. Undersökningen utgår från att marknaden är cyklisk och att fler kriser kommer uppkomma i framtiden. Den senaste krisen ägde rum under år 2007-2008 och har därför valts ut för att representera den tidsperiod som avser att analyseras. Bland annat har en generell hypotes testats gällande att icke-professionella kunder har en återkommande tendens att i extrema marknadslägen köpa vid uppgång och sälja vid nedgång i de utvalda tillväxtmarknadsfonderna. Utgångspunkten var i detta hänseende att förkasta denna hypotes, vilket tydligt visade sig stämma i en av de fonder som studerats. Resultatet visar i korthet att fler personer i medelåldern investerar mer än de i ungdomens år och pensionsåldern. Slutsatsen av undersökningen visar på att när detta krisläge uppstod skedde inga större uttag ur någon av fonderna. De facto minskar säljtransaktionerna överlag från toppnoteringen på börsen under år 2007 till bottennoteringen år 2008

Chemical structure matching using correlation matrix memories

This paper describes the application of the Relaxation By Elimination (RBE) method to matching the 3D structure of molecules in chemical databases within the frame work of binary correlation matrix memories. The paper illustrates that, when combined with distributed representations, the method maps well onto these networks, allowing high performance implementation in parallel systems. It outlines the motivation, the neural architecture, the RBE method and presents some results of matching small molecules against a database of 100,000 models

A simple model of the Belousov-Zhabotinsky reaction from first principles

The Belousov-Zhabotinsky (BZ) reaction is an example of a temporally oscillating chemical reaction. An unusual and interesting feature of the reaction is that as it progresses on a twodimensional plate, self-organized spirals are formed. Many computer models have been constructed of the BZ reaction to simulate the evolution of these spirals. The models typically use cellular automata to allow progression of a wavefront through a notional substrate. Usually a single substrate is used with somewhat arbitrary transference rules. Here it is shown that cellular automata models of BZ spirals can be created by using a very simple set of equations based on a three substrate model with close connection to reaction-diffusion models, more closely resembling the actual BZ reaction. Source code for the model is given in the Processing language

Stitching together the fabric of space and society: an investigation into the linkage of the local to regional continuum

To date, space syntax models have focused typically on relatively small areas up to the city scale. There have been very few models that take into account the entire network up to the regional scale, so the cumulative effects of micro-scale connections on regional networks is unknown, and the performance of the regional network as a function of the local area cannot be assessed. As such, a complete understanding of the ways in which regional centres are co-dependent and cities relate to their surrounding sub-centres is lacking. This study models the entire road network at the regional scale, by dispensing with axial lines entirely and moving to a road-centre line model of the UK, the Ordnance Survey's Integrated Transport Network (ITN) layer. This layer includes the topological connections between roads, so that a complete topological model of the road network including the directionality of streets can be constructed quickly. A region of the North of England - including Manchester, Bradford, Sheffield and Leeds - is analysed. Regional level angular analysis is shown to correlate well with overall movement in the network, while local level metric analysis is shown to correlate with the population density. It is hypothesised that combined measures that link the global to the local will uncover discontinuities in the continuum of space, and that these disruptions to the network will correspond to social deprivation. However, although such discontinuities exist, experimental linkage of the analysis to deprivation indices by census areas shows little conclusive evidence. In particular, it is clear that the complex web of spatial factors uncovered need investigation with more sensitive tools and smaller units of aggregation. The study highlights the need for a set of combined measures using microscopic spatial, economic, demographic, and land-use data, in order to further understand the relationship of spatial factors with social activity, while reinforcing standard space syntax results at the regional level