A New Scheme for Minimizing Malicious Behavior of Mobile Nodes in Mobile Ad Hoc Networks

The performance of Mobile Ad hoc networks (MANET) depends on the cooperation of all active nodes. However, supporting a MANET is a cost-intensive activity for a mobile node. From a single mobile node perspective, the detection of routes as well as forwarding packets consume local CPU time, memory, network-bandwidth, and last but not least energy. We believe that this is one of the main factors that strongly motivate a mobile node to deny packet forwarding for others, while at the same time use their services to deliver its own data. This behavior of an independent mobile node is commonly known as misbehaving or selfishness. A vast amount of research has already been done for minimizing malicious behavior of mobile nodes. However, most of them focused on the methods/techniques/algorithms to remove such nodes from the MANET. We believe that the frequent elimination of such miss-behaving nodes never allowed a free and faster growth of MANET. This paper provides a critical analysis of the recent research wok and its impact on the overall performance of a MANET. In this paper, we clarify some of the misconceptions in the understating of selfishness and miss-behavior of nodes. Moreover, we propose a mathematical model that based on the time division technique to minimize the malicious behavior of mobile nodes by avoiding unnecessary elimination of bad nodes. Our proposed approach not only improves the resource sharing but also creates a consistent trust and cooperation (CTC) environment among the mobile nodes. The simulation results demonstrate the success of the proposed approach that significantly minimizes the malicious nodes and consequently maximizes the overall throughput of MANET than other well known schemes.Comment: 10 pages IEEE format, International Journal of Computer Science and Information Security, IJCSIS July 2009, ISSN 1947 5500, Impact Factor 0.42

Oviposition behaviour and life-history performance of Epiphyas postvittana (Lepidoptera: Tortricidae) on the leaves of Vitis vinifera (Vitales: Vitaceae) infected with Botrytis cinerea (Helotiales: Sclerotiniaceae)

In three-way interaction systems involving an insect and a plant-pathogenic fungus, both occurring on the same plant, the insects generally gain in terms of their growth and metabolism. In this study we have tested how the infection by Botrytis cinerea on the leaves of Vitis vinifera influences the life-history performance of larvae and the oviposition behaviour of Epiphyas postvittana. We conducted free-choice and two-choice experiments to test the oviposition behaviour of gravid E. postvittana. We also characterized the effects of B. cinerea-infected leaves of V. vinifera on the growth and development of E. postvittana. We found that the oviposition preference of E. postvittana was strongly influenced by the olfactory and tactile cues. Volatiles from B. cinerea-infected plants significantly deterred oviposition and in consequence, adult females laid fewer number of eggs on B. cinerea-infected leaves of V. vinifera compared with uninfected leaves. The mortality rate of larvae fed on B. cinerea-infected leaves were not significantly different from the larvae fed on uninfected leaves of V. vinifera. Whereas, the larvae of E. postvittana fed on B. cinerea-infected leaves had significantly shorter developmental period, attained heavier pupal mass, and on becoming adults they laid more numbers of eggs than the larvae that were enabled to feed on uninfected leaves of V. vinifera. We also reared the larvae of E. postvittana on exclusive-fungus diet but all larvae died before pupation indicating that for a better larval performance and adult reproductive output of E. postvittana, the V. vinifera-B. cinerea interacting system is but imperative

A Novel Approach for Creating Consistent Trust and Cooperation (CTC) among Mobile Nodes of Ad Hoc Network

The final publication is available at www.springerlink.comThis paper provides a critical analysis of the recent research wok and its impact on the overall performance of a mobile Ad hoc network. In this paper, we clarify some of the misconceptions in the understating of selfishness and miss-behavior of nodes. Moreover, we propose a mathematical model that based on the time division technique to minimize the node misbehavior by avoiding unnecessary elimination of bad nodes. Our proposed approach not only improves the resource sharing but also creates a consistent trust and cooperation (CTC) environment among the mobile nodes. We believe, that the proposed mathematical model not only points out the weaknesses of the recent research work but also approximates the optimal values of the critical parameters such as throughput, transmission over head, channel capacity etc. The simulation results demonstrate the success of the proposed approach that significantly minimizes the malicious nodes and consequently maximizes the overall throughput of the Ad Hoc network than the other well known schemes.http://link.springer.com/chapter/10.1007/978-1-4020-8737-0_9

A New Mathematical Model for Optimizing the Performance of Parallel and Discrete Event Simulation Systems

Null message algorithm is an important conservative time management protocol in parallel discrete event simulation systems for providing synchronization between the distributed computers with the capability of both avoiding and resolving the deadlock. However, the excessive generation of null messages prevents the widespread use of this algorithm. The excessive generation of null messages results due to an improper use of some of the critical parameters such as frequency of transmission and Lookahead values. However, if we could minimize the generation of null messages, most of the parallel discrete event simulation systems would be likely to take advantage of this algorithm in order to gain increased system throughput and minimum transmission delays. In this paper, a new mathematical model for optimizing the performance of parallel and distributed simulation systems is proposed. The proposed mathematical model utilizes various optimization techniques such as variance of null message elimination to improve the performance of parallel and distributed simulation systems. For the sake of simulation results, we consider both uniform and non-uniform distribution of Lookahead values across multiple output lines of an LP. Our experimental verifications demonstrate that an optimal NMA offers better scalability in parallel discrete event simulation systems if it is used with the proper selection of critical parameters

Investigating the Effects of Trees and Butterfly Barriers on the Performance of Optimistic GVT Algorithm

The final publication is available at www.springerlink.comThere is two approaches for handling timing constraints in a heterogeneous network; conservatives and optimistic algorithms. In optimistic algorithms, time constraints are allowed to be violated with the help of a time wrap algorithm. Global Virtue Time (GVT) is a necessary mechanism for implementing time wrap algorithm. Mattern [2] has introduced an algorithm for GVT based computation using a ring structure. which showed high latency. The performance of this optimistic algorithm is optimal since it gives accurate GVT approximation. However, this accurate GVT approximation comes at the expense of high GVT latency. Since this resultant GVT latency is not only high but may vary, the multiple processors involve in communication remain idle during that period of time. Consequently, the overall throughput of a parallel and distributed simulation system degrades significantly In this paper, we discuss the potential use of trees and (or) butterflies structures instead of the ring structure. We present our analysis to show the effect of these new mechanisms on the latency of the system.http://link.springer.com/chapter/10.1007%2F978-90-481-3660-5_7

A Novel Approach of Using Data Guard for Disaster Recovery & Rolling Upgrades

© ASEE 2008Though we already had a standardized way (from Oracle) for Disaster Recovery policy, a major crash of the PLM database made our DBAs to come up with a proposal to execute a procedure using Data Guard together with Oracle Transportable Tablespace which resulted in the successful and timely migration of the PLM Production from Oracle 9.2.0.3 on HP N-Class to Oracle 9.2.0.5 on HP-Superdome in just 8 minutes. This same procedure also gives a fast, reliable way to upgrade from Oracle9i to Oracle Database10g with minimal downtime. And future database upgrades get even easier using Data Guard 10g Rolling Upgrades

EFFECT OF PIGEON ORIGIN NEWCASTLE DISEASE VIRUS ON VARIOUS LIVER ENZYMES AND ASSOCIATED PATHOLOGICAL CHANGES IN EXPERIMENTALLY INFECTED PIGEONS

Newcastle disease virus (NDV) was isolated from a field outbreak in pigeons. The virus was characterized by haemagglutination test (HA) and confirmed by haemagglutination inhibition test (HAI). The pathotyping was done by mean death time (MDT), intracerebral pathogenicity index (ICPI) and intravenous pathogenicity index (IVPI). The ELD50 of the velogenic strain was 10-4.66/0.1 ml. Thirty-nine pigeons were randomly divided into three equal groups. Pigeons of one group were vaccinated with ND vaccine (LaSota strain) intraocularly after 14 days of procurement, while the other two groups served as vaccinated and non-vaccinated controls. Birds of these two groups were challenged with velogenic strain of field isolate of NDV 7 days post-vaccination. Birds were kept under observation for 15 days post-challenge. Haemorrhages and congestion were observed in trachea, lungs, liver, proventriculus and intestine of pigeons infected with NDV. Concentrations of AST, ALT and ALP did not differ among pigeons of the three groups

Moisture effects on the bending fatigue of laminated composites

This paper investigated the effect of moisture ingress on the bending fatigue of laminated composites. An accelerated testing method was developed to investigate the correlation between composite fatigue and moisture diffusion effects. Unidirectional and cross-ply laminated CFRP composites were manufactured in autoclave, and then submerged in both fresh and seawater for various periods until moisture saturation. Quasi-static and cyclic tests were carried out in both air and wet environment, and the failure mechanisms were investigated using visual and microscopic methods. Additionally, a robust 2D Finite Element model (FEA) was developed to simulate the fatigue crack propagation based on virtual crack closure technique (VCCT), while a 3D FEA model was developed to investigate the edge effect on fatigue crack propagation. The experimental observations gave a good agreement with the FEA models. The study showed that the bending fatigue failure was due to the so-called buckling-driven delamination, and the fatigue life was reduced significantly owing to the combination of edge effect and capillary effect. The fatigue test indicated that the fatigue resistance was degraded one stress level due to the water ingress, e.g. from 80% ultimate flexural strength (UFS) to 65% UFS. Therefore, a 4-step fatigue failure theory was proposed to explain the moisture effects on the crack propagation under bending fatigue

A Mathematical Model for Evaluating the Performance of Multicast Systems

© 2008 IEEE. Reprinted, with permission, from Syed S. Rizvi, Aasia Riasat, and Khaled M. Elleith, "A Mathematical Model for Evaluating the Performance of Multicast Systems," The 1st IEEE International Workshop on IP Multimedia Communications (IPMC 2008) August 4 - 7, 2008, St. Thomas U.S. Virgin IslandsThe Internet is experiencing the demand of high-speed real-time applications, such as live streaming multimedia, videoconferencing, and multiparty games. IP multicast is an efficient transmission technique to support these applications. However, there are several architectural issues in this technique that hinder the development and the deployment of IP multicast such as a lack of an efficient multicast address allocation scheme. On the other hand, End System Multicasting (ESM) is a very promising application-layer scheme where all the multicast functionality is shifted to the end-users. Supporting high-speed real-time applications always demand a sound understanding of these schemes and the factors that might affect the end-user requirements. In this paper we attempt to propose both analytical and the mathematical models for characterizing the performance of IP multicast and ESM. Our proposed mathematical model can be used to design and implement a more efficient and robust ESM model for the future networks