Contenu du sommaire

Serge THIBAULT, Fractals and the structure of urban rainwater run-off systems. The evolution of the concept and management of rainwater run-off systems is the starting point for this research, which consists in linking the hydrological function of urban drainage pools to the morphology of the drainage systems. This latter element can be formulated as a model by means of fractal dimension theory. Thus, a system is defined as an arrangement of sections composing a spatial form, whose dimension can be understood as between one and two. This model, while taking into account the greater or lesser complexity of the object in question, is at the same time characterized by properties which illustrate an urban form via a particular technical network. We hope that this approach can be extended to other technical networks.

Paul A. DAVID & Julie A. BUNN, The economics of gateway technologies and network evolution. This paper is concerned with the role played by so-called gateway technologies in the development of network industries. They rest their argument on a real-life example: the influence of the rotary converter innovation on the expansion of a.cj technology (and the eviction of d.c.) in the power supply industry in the US at the turn of the century (1890-1910). The first part of the paper is published here. First the authors suggest modified definitions, based on different technical examples, of widely-used concepts, such as innovation, standard, compatibility, and introduce a new concept, that of gateway technologies (between incompatible syb-systems). And secondly they examine the historical context of the 'Battle of the Currents' that burst into public view in the US at the end of the 1880s, as well as subsequent interpretations of it in the literature. In the second part of the paper, to be published in FLUX no.6, the authors re-examine these historical events, while more particularly laying stress on the influence of the rotary converter, viewed as a gateway innovation.

Hermann KORTE, The development of "infrastructure" in the Ruhr, 1840-1990, Part I: the railroads. Infrastructure, that is, basic economic functions under public control, develops according to an unplanned process, made of a succession of decisions forming a structured sequence of events. The study of the social and economic history of the Ruhr from the beginning of industrialization illustrates this theoretical point of view. Thus, the railroad evolves according to increasing concentration phases. The State progressively organizes and controls private initiatives into nationalization and eventually, monopoly (this forms the subject of Part I, published in this issue of FLUX). In the case of water distribution and purification, the State merely plays the role of encouraging cooperation. In the institution of the union can also be found, in the case of the Rurh, a typical compromise, in which the State is merely the solicitor with respect to cooperative agreements between local partners (Part 2, to be published in FLUX 6). Ruhr from the beginning of industrialization illustrates this theoretical point of view. Thus, the railroad evolves according to increasing concentration phases. The State progressively organizes and controls private initiatives into nationalization and eventually, monopoly (this forms the subject of Part I, published in this issue of FLUX). In the case of water distribution and purification, the State merely plays the role of encouraging cooperation. In the institution of the union can also be found, in the case of the Rurh, a typical compromise, in which the State is merely the solicitor with respect to cooperative agreements between local partners (Part 2, to be published in FLUX 6).