Extending TRANSIMS Technology to an Integrated Multilevel Representation

The TRANSIMS system developed at Los Alamos in the USA over the past decade is a world leader in providing an integrated land-use transportation dynamical model for large areas with a million or more inhabitants. TRANSIMS uses standard survey data to create synthetic micropopulations, including family structure, to simulate trip making and emergent traffic dynamics. We propose to extend TRANSIMS by adapting it to a new multi-level representation, allowing dynamics to be algebraically integrated at the micro-, meso- and macro-levels. The new representation builds a lattice hierarchy in a way that integrates non-partitional hierarchies of links and routes based on the usual hierarchy of geographical zones, e.g. neighbourhoods, districts, cities, counties and countries. Applying the representation to a big city starts by defining sets of zones at different levels. At the first level, N, is the street. This can be subdivided to building plots at level N-1, buildings at level N-2, and even rooms at level N-3. At level N+1 are the neighbourhoods, at level N+2 is the set of district zones (each of them containing the different neighbourhoods in the previous level), and at the top level N+3 (in this case), is just one zone, the city itself. If a larger study area is to be considered, we would have a whole set of N+3 zones defining N+4-level areas, and so on, extending to the level of counties, countries or even continents. This paper will explain the fundamentals of TRANSIMS technology and compare it to other systems. We will show how TRANSIMS and the new multi-level representation can be brought together to give new insights into the macro-dynamics of very large road systems such as London, England and even the whole of Europe

Gravity vs radiation model: on the importance of scale and heterogeneity in commuting flows

We test the recently introduced radiation model against the gravity model for the system composed of England and Wales, both for commuting patterns and for public transportation flows. The analysis is performed both at macroscopic scales, i.e. at the national scale, and at microscopic scales, i.e. at the city level. It is shown that the thermodynamic limit assumption for the original radiation model significantly underestimates the commuting flows for large cities. We then generalize the radiation model, introducing the correct normalisation factor for finite systems. We show that even if the gravity model has a better overall performance the parameter-free radiation model gives competitive results, especially for large scales.Comment: in press Phys. Rev. E, 201

The multilevel dynamics of very large complex road systems

Abstract not available

Multidimensional multilevel representation for traffic simulation models

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Extending Eiffel as a full life-cycle language

One of the Object Technology goals is to offer a seamless transition in the development of systems. One way to ensure this seamless transition is using the same language throughout the process in order to avoid the need for translations between phases or activities. In this paper we present an extension to Eiffel which we propose as a full life-cycle language. This language is capable of being a lingua franca between different analysis and design methodologies and their notations and the CASE tools which support them.Postprint (published version

Extending Eiffel as a full life-cycle language

One of the Object Technology goals is to offer a seamless transition in the development of systems. One way to ensure this seamless transition is using the same language throughout the process in order to avoid the need for translations between phases or activities. In this paper we present an extension to Eiffel which we propose as a full life-cycle language. This language is capable of being a lingua franca between different analysis and design methodologies and their notations and the CASE tools which support them

Design quality metrics for object-oriented software development

The availability of metrics for measuring software design quality and complexity are a great help in the development of such systems. Applications of such metrics in the initial stage of the software development process (specification, analysis, and design) allows us to detect those software designs which are excessively complex or intricate at a time when correction costs are still low. In this way, we are able to avoid all the negative consequences that badly-designed systems may involve, such as high maintenance cost, poor re-use, proneness to error, low portability to different environments, ... Whereas there is a large number of studies and reviews on the measurement of systems which have been developed by means of procedural methods, this is not the case for systems designed through the object-oriented paradigm. In this paper we present a collection of measures which can be useful for measuring object-oriented systems and which may also help to extend the research so far carried out in this field.Postprint (published version

Design quality metrics for object-oriented software development

The availability of metrics for measuring software design quality and complexity are a great help in the development of such systems. Applications of such metrics in the initial stage of the software development process (specification, analysis, and design) allows us to detect those software designs which are excessively complex or intricate at a time when correction costs are still low. In this way, we are able to avoid all the negative consequences that badly-designed systems may involve, such as high maintenance cost, poor re-use, proneness to error, low portability to different environments, ... Whereas there is a large number of studies and reviews on the measurement of systems which have been developed by means of procedural methods, this is not the case for systems designed through the object-oriented paradigm. In this paper we present a collection of measures which can be useful for measuring object-oriented systems and which may also help to extend the research so far carried out in this field