Eaodv: A*-based Enhancement Ad-hoc on Demand Vector Protocol to Prevent Black Hole Attacks

Black hole attack is an attack where a node that responds to RREQ from the source node by replying a fake freshness information and false hop count. The black hole nodes do not respond to distributed co-operation in routing protocol to absorb all the packets, as a result, the network performance will drop. Most previous works are focused on anomaly detection through dynamic trusted of the neighbouring nodes. We find out that the internal comparisons take a long time. This loss can be shortened by changing the routing mechanism. We propose an enhancement of AODV protocol, named EAODV, that is able to prevent black hole attacks. The EAODV can find a shortest path of routing discovery using A* heuristic search algorithm. Values of hop count and estimate time to reach the destination node are used as input in the heuristic equation and one-way hash function is used to make a secure value and then to casting it to all neighbouring nodes. Experiments were conducted in NS2 to simulate EAODV in different running time with and without black hole nodes. The EAODV performance results are indicated better in terms Packet loss and Average End-to-End delay

Dimensional-analysis and similitude for scale-up of solid-liquid extraction of eurycoma longifolia roots

A dimensionless model was proposed to scale-up the solid-liquid extraction of Eurycoma longifolia roots. ShSc−1 dimensionless number was found to be the best fit of all proposed models. At optimum conditions of the extraction process, which were duration of extraction of 53 min, solvent to raw material ratio of 12.5:1 and roots particle size of 0.5 to 1.0 mm, the extract yield of 8.76% at lab-scale produced ShSc−1 no. of 0.0312. Employing the scale up rule of P/V idem and scale-up factor of 7.65, the extract yield of 8.65% with 1.37% error was obtained at pilot-scale at ShSc−1 no. of 0.0376. The outcome of this study provided useful scale-up knowledge in ensuring smooth transition from lab-scale to pilot-scale