Operation and modelling of an updraft long-stick wood gasifier

Even though biomass gasification technology has come up in the past with impressive applications, the exact details of the gasification process are yet to be completely understood quantitatively. On the basis of the experience of gasifier users with regard to the efforts and energy needed for wood chip preparation in a typical gasifier, we have embarked on the development of a gasifier suitable to work with long-stick woody biomass as the feed material to avoid major fuel preparation problems in rural settings. With this concept, a 25m 3 /hr capacity updraft gasifier was designed and constructed. Since the interest here is in exploring and validating this concept, an updraft gasifier was designed. This gasifier attains a high-energy release rate per unit area due to high inlet air velocity and activated reaction in the combustion zone. The temperature ranged from 922º C in the combustion zone to 128º C in the drying zone. In all the zones, the heat balance equations show a good fit between the theoretical and experimental values. The gasifier was operated in a batch mode, both bottom-lit (conventional) and top-lit, and the air flow and gas outflow were measured. The temperature of the raw gas was measured. The gas and air flows can be converted to the air/fuel ratio (A/F), the most important aspect of gasifier operation. A/F shows operation in a combustion mode at start-up, a gasification mode for the middle part of the run and a charcoal gasification mode at the end of the run. For modelling, the gasifier was divided into a drying zone, a pyrolysis zone, a combustion zone and a reduction zone

The state of peer-to-peer network simulators

Networking research often relies on simulation in order to test and evaluate new ideas. An important requirement of this process is that results must be reproducible so that other researchers can replicate, validate and extend existing work. We look at the landscape of simulators for research in peer-to-peer (P2P) networks by conducting a survey of a combined total of over 280 papers from before and after 2007 (the year of the last survey in this area), and comment on the large quantity of research using bespoke, closed-source simulators. We propose a set of criteria that P2P simulators should meet, and poll the P2P research community for their agreement. We aim to drive the community towards performing their experiments on simulators that allow for others to validate their results

Ecological phytochemistry of Cerrado (Brazilian savanna) plants

The Cerrado (the Brazilian savanna) is one of the vegetation formations of great biodiversity in Brazil and it has experienced strong deforestation and fragmentation. The Cerrado must contain at least 12,000 higher plant species.We discuss the ecological relevance of phytochemical studies carried out on plants from the Cerrado, including examples of phytotoxicity, antifungal, insecticidal and antibacterial activities. The results have been classified according to activity and plant family. The most active compounds have been highlighted and other activities are discussed. A large number of complex biochemical interactions occur in this system. However, only a small fraction of the species has been studied from the phytochemical viewpoint to identify the metabolites responsible for these interactions