A multipath routing strategy to prevent flooding disruption attacks in link state routing protocols for MANETs

Multipath routing has been proposed to increase resilience against network failures or improve security in Mobile Ad Hoc Networks (MANETs). The Optimized Link State Routing (OLSR) protocol has been adopted by several multipath routing strategies. They implement Multipoint Relay (MPR) nodes as a flooding mechanism for distributing control information. Ideally, the construction of multiple disjoint paths helps to increase resilience against network failures or malicious attacks. However, this is not always possible. In OLSR networks, partial link-state information is generated and flooded exclusively by the MPRs. Therefore, the nodes only obtain a partial view of the network topology. Additionally, flooding disruption attacks may affect either the selection of the MPRs or the propagation of control traffic information. As a consequence, the chances of constructing multiple disjoint paths are reduced. We present a strategy to compute multiple strictly disjoint paths between any two nodes in OLSR-based networks. We provide mechanisms to improve the view of the network topology by the nodes, as well as handling potential flooding disruption attacks to the multipath construction mechanism in OLSR-based networks. We conduct simulations that confirm our claims.     

Selective removal of sulphur in liquid fuels for fuel cell applications

Fuels like diesel and gasoil must be desulphurised to extremely low levels before being used as hydrogen source for modern fuel cell applications and to avoid sulphur poisoning of therein used catalysts. A commercial Ni/NiO-sorbent has been identified as being able to remove even refractory sulphur species like 4,6-dimethyldibenzothiophene and the total sulphur concentration is lowered to below 0.2 ppm. The influence of temperature, residence time and level of the sulphur content in the untreated fuel has been investigated in parametric studies. Gas chromatography with mass spectrometric detection (GC–MS) of treated gasoils and diesels reveal which sulphur species are selectively removed and which are left in the fuel. The selectivity and activity of the sorbent can be influenced by the operating temperature. Moreover, GC–MS chromatograms of the breakthrough curves reveal that the sorbent capacity is related to specific sulphur species. Their molecular structure and the alkyl groups at the 4- and 6-positions of dibenzothiophene as well as the C₃-benzothiophenes influence the adsorption and the sorbent capacity significantly.