in this work, the waste stone sludge obtained from the granite and marble stone processing factories was used for the manufacture of artificial stones using vibratory compaction in a vacuum environment. the results obtained showed that water absorption and density increased, and the flexure, compressive, and tensile strengths decreased with increase in the content of the waste stone sludge. the...

We introduce nutrient recycling into a model where competitors differ in the scale at which they perceive their environment. In a two-resource system with both external nutrient inputs and recycling, larger consumers ("integrators") often generate resource distributions that favor their smaller ("nonintegrator") competitors, and vice versa. This occurs because recycling of integrator biomass re...

Contaminants cause a decrease in the quality of materials with each recycling step. These quality losses should be minimized to increase the sustainability of resources use. Quality losses cannot be measured using weight-based recovery definitions alone, as the quality degradation cannot be translated by mass measures. Therefore, a better measure of the efficiency of resource use is investigate...

Article history: Received 25 September 2007 Received in revised form 4 November 2008 Accepted 7 November 2008 Available online 7 December 2008 Phosphorus (P) is an essential input into agriculture with no substitute. Thus international and intertemporal P allocations greatly impact food security which requires increased food production for a growing world population. As high quality phosphorus ...

This paper considers the relocation problem arising from public re-development projects cast as a two-machine flowshop scheduling problem. In such a project, some buildings need to be torn down and re-constructed. The two processes of tearing down and re-constructing each building are often viewed as a single operation. However, under certain circumstances, the re-construction process, i.e., th...