Analytical modelling of Breathing Walls: experimental verification by means of the Dual Air Vented Thermal Box lab facility
Abstract Breathing Walls are air permeable envelope components based on porous materials. In contra-flux operation air flows opposite to conductive flux, while in pro-flux they have the same direction. The Breathing Wall behaves either as a ventilation heat exchanger or as an active insulation. In literature an analytical model describing steady state heat transfer across a Breathing Wall can be found. Since it lacks an exhaustive experimental validation, a facility developed at the Energy Department of Politecnico of Milano was used to investigate the thermo-physical behavior of a no-fines concrete based Breathing Wall in steady state Dirichlet conditions and contra-flux operation.
This paper presents a study of the technical efficiency of industries in a transitional economy: China. Using data for 28 manufacturing industries across 29 provinces and the Data Envelopment Analysis approach, the technical efficiency of each industry is measured and compared across regions and provinces. The determinants of differential technical efficiency performance are analysed, with a particular focus on the impact of trade orientation and foreign investment. Trade openness is found generally to have a positive effect on technical efficiency.