Positive development

net sustainability. At best they reduce relative resource consumption. They still consume vast quantities of materials, energy, water and ecosystems during construction. Moreover, green buildings replace land and ecosystems with structures that, at the very best, only 'mimic' ecosystems<'). Mimicking nature is little compensation when we have lost a third of species that are integral parts of our life support system. Already, development has exceeded the Earth's ecological carrying capacity, so even 'restorative' design is not enough. Urban areas must be retrofitted to increase net bioregional carrying capacity - just to support existing or reduced population levels in cities. The eco-retrofitting of our built environment is therefore an essential precondition of achieving a sustainable society. But we need to eco-retrofit cities in ways that increase net sustainability, not just relative efficiency.

Prediction of fluidization behaviour and a quasi-stationary approach to drying kinetics of irregular particulate food materials

Changes in fluidization behaviour behaviour was characterised for parallelepiped particles with three aspect ratios, 1:1, 2:1 and 3:1 and spherical particles. All drying experiments were conducted at 500C and 15 % RH using a heat pump dehumidifier system. Fluidization experiments were undertaken for the bed heights of 100, 80, 60 and 40 mm and at 10 moisture content levels. Due to irregularities in shape minimum fluidisation velocity of parallelepiped particulates (potato) could not fitted to any empirical model. Also a generalized equation was used to predict minimum fluidization velocity. The modified quasi-stationary method (MQSM) has been proposed to describe drying kinetics of parallelepiped particulates at 30o C, 40o C and 50o C that dry mostly in the falling rate period in a batch type fluid bed dryer.