Kinetics and FTIR characteristics of the pyrolysis process of poplar wood

The pyrolysis characteristics of residues of poplar （Populus sp.） wood were investigated using a thermogravimetric analyzer coupled with a Fourier transform infrared （TG-FTIR） spectrometer. The pyrolysis process was sub- divided into four stages at a rate of 10℃.min-1, varying from 30 to 650℃. Below 180℃, a mass loss occurred for drying and preheating the sample and the onset temperature of pyrolysis ranged between 180-260℃. A significant mass loss 3f 61.4 wt.% occurred between 260-380℃, followed by a slow and continuous mass change with lignin devolatilization. The analysis of kinetic reactions showed that the activation energy （78.29 kJ.mol-1） in the low-temperature section was much larger than that （6.40 kJ-mol-1） in the high-temperature section. The evolved gases formed by thermal degradation 3f poplar wood were simultaneously analyzed by FTIR. It was observed from the main peaks that the emissions evolved during poplar wood pyrolysis were acetic acid, carbon dioxide, carbon monoxide, methane, water, some volatile com- 3ounds of esters, alcohols and aldehydes. The emissions gradually increased with rising temperatures before a strong 3eak around 360℃ and then decreased. Most gaseous products were emitted in the 320-380℃ range, while CO2 was =ontinuously emitted in a wide range from 140-550℃.

EDA: an enhanced dual-active algorithm for location privacy preservation in mobile P2P networks

Various solutions have been proposed to enable mobile users to access location-based services while preserving their location privacy. Some of these solutions are based on a centralized architecture with the participation of a trustworthy third party, whereas some other approaches are based on a mobile peer-to-peer (P2P) architecture. The former approaches suffer from the scalability problem when networks grow large, while the latter have to endure either low anonymization success rates or high communication overheads. To address these issues, this paper deals with an enhanced dual-active spatial cloaking algorithm (EDA) for preserving location privacy in mobile P2P networks. The proposed EDA allows mobile users to collect and actively disseminate their location information to other users. Moreover, to deal with the challenging characteristics of mobile P2P networks, e.g., constrained network resources and user mobility, EDA enables users (1) to perform a negotiation process to minimize the number of duplicate locations to be shared so as to significantly reduce the communication overhead among users, (2) to predict user locations based on the latest available information so as to eliminate the inaccuracy problem introduced by using some out-of-date locations, and (3) to use a latest-record-highest-priority (LRHP) strategy to reduce the probability of broadcasting fewer useful locations. Extensive simulations are conducted for a range of P2P network scenarios to evaluate the performance of EDA in comparison with the existing solutions. Experimental results demonstrate that the proposed EDA can improve the performance in terms of anonymity and service time with minimized communication overhead.