Security is an essential service for wired and wireless network communication. This work concerned with a particularly sever security attack that affects the ad hoc networks routing protocols, called "wormhole attack". There are many solutions to detect and prevent this attack like packet leashes, cluster base, hop count analysis etc., but none of them is perfect solution. This paper contains a proposal for new technique for wormhole avoidance. Proposed technique has been implemented with NS2 simulator over the DSR protocol. This technique for wormhole avoidance addresses the malicious nodes and avoids the routes having wormhole nodes without affecting the overall performance of the network. The performance metrics used for evaluating network performance are jitter, throughput and end to end delay. The performance of proposed techniques is good.
The primary objective of this research paper is to develop a dynamic nonlinear pH neutralization process model, based on physical and chemical principles that can represent the specific pH neutralization pilot plant. The accuracy of this model should be sufficient to allow development of conventional and advanced control systems through simulation for subsequent implementation and testing on the plant itself. The pH neutralization process is modeled based on the reaction between strong basic solution (NaoH) and strong acidic solution (H2SO4) in Continuous Stirred Tank Reactor (CSTR). From open loop response pH system is considered as First Oder plus Dead time process. Comparison was made between four strategies like ZN, Fruehauf et al, Original IMC and Min ISTSE tuning Methods of PI and PID controllers. From the simulation results Error Indices and Time domain specifications where calculated for different tunings methods of PI and PID controller.
S u m m a r yNyctanthes arbor tristis (NATE) ethanol extract (150 mg/kg, orally) was evaluated for its protective effect against scopolamine-induced (1 mg/kg i.p.) cognitive impairments in rats using behavioral models like radial arm maze test, Morris water maze test and active avoidance test. NATE effect was evaluated and compared with the standard piracetam (200mg/kg i.p.). NATE (p<0.005) significantly reversed the impairment produced by the scopolamine in radial arm maze test. In addition, NATE also decreased the time period taken to find the hidden platform in Morris water maze test and increased number of avoidances in active avoidance paradigm. Acetylcholinesterase activity and thiobarbituric acid levels were significantly (p<0.005) decreased along with the rise in activities of superoxide dismutase and catalase. This might suggest that the NATE has protective effect against scopolamine-induced cognitive impairment in rats through acetylcholine muscarinic receptor pathway and also antioxidant activity. No significant changes were found in histopathological studies of brain.
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