Gateways as inter-modal nodes in different ages: The Venetian region, eighteenth to twentieth centuries

This paper focuses on the theoretical implications of a regional case studyfor the analysis of transportation networks and gateway functions. Thestarting point is the result of a research on the changing role of gateways,and on the relocation of the gateway function from one city to a series ofcities in the Venetian region from the eighteenth to the twentieth century.Against this evolution, I test the validity and usefulness of a definition of thegateway as a point of inter-modal exchange for its historical interpretation.Changing transport technologies involve different organisations of inter-modal exchanges, and imply more or less intense economic functions ofgateway cities. These changes intertwine with political events and deci-sions, and more general economic changes: they could at the same time beread as an effect of these transformations, and as a causal factor. From this perspective, a study of intermodality shows to be useful to shed new lighton specific changes in the structure of urban hierarchie

L'et\ue0\ua0 moderna

Storia di Padova dall'et\ue0 romana al 200

Optimal conditions for avoiding emission of polynuclear aromatic hydrocarbons (PAH) during combustion of sherred recycled tire rubber

When burning in appropriate furnaces Tire Derived Fuel (TDF), emission of several Polynuclear Aromatic Hydrocarbon (PAH) specimens may occur if optimal conditions are not fulfilled. The exhaust fingerprint pattern ensuing from the equilibrium between pyrosynthesis vs. pyrolysis processes depends on the operating parameters of the furnace chamber. The investigated parameters were: temperature, air shortage, addition of preheated air, exhaust residence time, and presence of cement flour. To scan such conditions, five laboratory combustion simulations were carried out in the range of 400-1000°C. These experiments showed that burning TDF at 800°C is normally optimal for massive PAH production. By contrast, in highly oxidizing conditions above 1000°C and short residence time with no cement flour, only environmentally insignificant amount of PAH (especially those carcinogenic) are generated. Because cement industrial furnaces generally reach temperatures well above 1000°C and may easily fulfill optimal conditions, disposed tires can be conveniently exploited as an economic and environmental friendly alternative fuel. Copyright Enviromedia