Routing Topologies of Wireless Sensor Networks for Health Monitoring of a Cultural Heritage Site.

This paper provides a performance evaluation of tree and mesh routing topologies of wireless sensor networks (WSNs) in a cultural heritage site. The historical site selected was San Juan Bautista church in Talamanca de Jarama (Madrid, Spain). We report the preliminary analysis required to study the effects of heating in this historical location using WSNs to monitor the temperature and humidity conditions during periods of weeks. To test which routing topology was better for this kind of application, the WSNs were first deployed on the upper floor of the CAEND institute in Arganda del Rey simulating the church deployment, but in the former scenario there was no direct line of sight between the WSN elements. Two parameters were selected to evaluate the performance of the routing topologies of WSNs: the percentage of received messages and the lifetime of the wireless sensor network. To analyze in more detail which topology gave the best performance, other communication parameters were also measured. The tree topology used was the collection tree protocol and the mesh topology was the XMESH provided by MEMSIC (Andover, MA, USA). For the scenarios presented in this paper, it can be concluded that the tree topology lost fewer messages than the mesh topology.

Monitoring of freeze-thaw cycles in concrete using embedded sensors and ultrasonic imaging.

This paper deals with the study of damage produced during freeze-thaw (F-T) cycles using two non-destructive measurement approaches-the first approach devoted to continuous monitoring using embedded sensors during the cycles, and the second one, performing ultrasonic imaging before and after the cycles. Both methodologies have been tested in two different types of concrete specimens, with and without air-entraining agents. Using the first measurement approach, the size and distribution of pores were estimated using a thermoporometrical model and continuous measurements of temperature and ultrasonic velocity along cycles. These estimates have been compared with the results obtained using mercury porosimetry testing. In the second approach, the damage due to F-T cycles has been evaluated by automated ultrasonic transmission and pulse-echo inspections made before and after the cycles. With these inspections the variations in the dimensions, velocity and attenuation caused by the accelerated F-T cycles were determined.

Assessing the environmental benefit of a new fertilizer based on activated biochar applied to cereal crops.

This study analyzes the environmental benefits that a nitrogen fertilizer based on activated biochar has in comparison to other traditional fertilizers (urea, ammonium nitrate (AN), ammonium sulfate (AS) and di-ammonium phosphate (DAP)). With this aim, activated biochar was generated from residual biomass (barley straw) through physical activation and the resulting biochar was combined with mineral fertilizer to synthethise the fertilizer. This new product was subjected to environmental assessment by means of two different approaches, Life Cycle Assessment (LCA) and nitrogen footprint procedure, both of which considered standard conditions typical of Mediterranean climate and wheat and corn as the fertilized crops. Emission factors of traditional fertilizers were obtained from internally developed models, which were in turn based on real data from literature. As for emission factors of the new product, they were calculated basing on experimental results. Fertilizer impacts in terms of acidification, eutrophication and climate change were estimated, thus revealing a great performance of activated biochar over other fertilizers in terms of reactive nitrogen (Nr), reaching a maximum saving rate of 63% in the amount of Nr released by volatilization and leaching. In addition, this work offers a methodology for environmental analysis of fertilizers and provides useful quantitative indicators for the environmental benefit and the saving of reactive nitrogen, which could contribute to the development of new commercial low N-emissions fertilizers.