Sunita Prasad

An elitist nondominated sorting genetic algorithm for QoS multicast routing in wireless networks

Abstract Due to the increasing popularity of real time multimedia applications, Quality-of-Service (QoS) based multicast routing has emerged as an active area of research. The fundamental requirements of many multimedia applications are cost minimization and bounded end-to-end delay. In addition, video data traffic is sensitive to packet loss and delay variance. Hence, multiobjective optimization seems to be the most appropriate method for such complex problems. We, therefore, formulate QoS based multicast routing as a multiobjective optimization problem using Elitist Nondominated Sorting Genetic Algorithm (NSGA-II). To enhance the performance of NSGA-II, we propose a new encoding scheme that aims to achieve a diversified solution set and faster convergence of search towards optimal Pareto front. It has also been observed that identical solutions cause loss of diversity which degrades the performance of NSGA-II algorithm. To overcome this drawback, the second enhancement based on replacement strategy is used. In this approach, one copy of identical solution is retained and new random solutions are introduced in the population to obtain a well distributed Pareto front. The results of new encoding scheme and replacement strategy are compared with other existing evolutionary multiobjective algorithms to demonstrate the effectiveness of the proposed approach. To further strengthen the usefulness of modified algorithm, the experimental results are validated using statistical significance tests.

TS-LocalRank: A topic similarity local ranking algorithm for re-ranking web search results

This paper proposes a variant of the PageRank algorithm to apply for re-ranking web search results. The algorithm (named TS-LocalRank) obtains top N pages from search results of a major search engine, assigns a local rank to each page based on the topic similarity between the web pages, re-orders the web pages, and presents the results to users. The objectives of this algorithm are (i) to assign a high local rank to the web pages which are most relevant to user query, and (ii) to minimize the Mean Absolute Deviation of the similarity between web pages in top search results.

Ant based Pareto optimal solution for QoS aware energy efficient multicast in wireless networks

The graphical abstract in the form of Pareto front solutions showing the trade-offs between the objectives is depicted in Fig. 1.Display Omitted Wireless networks have finite battery source, so QoS aware multicast routing must also be energy efficient.There is trade-off between energy consumption and QoS guarantees (i.e. end-to-end delay, delay jitter and packet loss) provided by a wireless network.These requirements are formulated as a multiobjective optimization problem.Ant based multiobjective algorithms are proposed to build an energy efficient multicast tree.Simulation results are compared with NSGA-III. Most of the group communication technologies support real-time multimedia applications such as video conferencing and distributed gaming. These applications require quality-of-service (QoS) aware multicast routing protocol to deliver the same data stream to a predefined group of receivers. Since nodes in wireless networks are severely energy constrained due to finite battery source, hence it is of paramount importance that QoS aware multicast routing protocol be energy efficient. Transmission power control is one of the methods used to save energy. In this method, the nodes dynamically adjust the transmission power so that energy consumption in the tree is minimized. However, reduction in the transmission power increases the number of forwarding nodes in the multicast tree. This negatively impacts the QoS in terms of propagation delay, delay jitter, and packet loss etc. In wireless networks, there is a trade-off between the energy consumption and the QoS guarantees provided by the network. We unify these requirements into a multiobjective framework referred to as Energy Efficient QoS Multicast Routing (E2QoSMR). The goal is to simultaneously optimize the total power consumption and the QoS parameters in the multicast tree. We extend two algorithms based on metaphor of swarm intelligence for finding an energy efficient multicast tree satisfying the QoS guarantees. Extensive simulations have been conducted to validate the correctness and efficiency of the algorithms. The simulation result of the algorithms is compared with the nondominated sorting genetic algorithm, NSGA-III. The experimental results are consolidated by statistical analyses that demonstrate the ability of the algorithms to generate the Pareto optimal solution set.

Spectroscopic Investigation of Tungsten Ions in Lead Scandium Phosphate Glass System

ABSTRACT Lead scandium phosphate glasses (PbO-Sc2O3-P2O5) containing different concentrations of tungsten oxide (WO3) ranging from 0 to 5 mol% were prepared. A number of studies, viz. differential thermal analysis (DTA), infrared spectra, optical absorption, and electron spin resonance (ESR) spectra, have been carried out. The results of DTA indicated the highest glass forming ability for the glass containing 5 mol% of WO3. The results of spectroscopic studies have been analyzed in light of different oxidation states of tungsten ions.

Security Enhancement in Data Encryption Standard

Data Encryption Standard (DES) is the most widely used cryptosystem. Faster computers raised the need of high security cryptosystems. Due to its small key length and simple feistel network, many cryptanalysts developed various methods, like parallel and exhaustive attack, to break DES. DES is most vulnerable to differential cryptanalysis attack. This paper proposes modifications in DES to ensure security enhancement by improving the key length and the weak round function against cryptographic attacks. We show analytically that the modified DES is stronger against cryptographic attacks. The proposed modifications divide the expanded 48 bits of right block into two equal blocks of 24 bits. Then two different functions are performed on these two blocks. The effective key length is increased to 112 bits by using 2 keys. These two keys are used in special sequence with round numbers. The analysis shows that for the proposed approach, the probability of characteristic for differential cryptanalysis is reduced and the unicity distance is better as compared to standard DES.

Low voltage low power sub-threshold operational amplifier in 180nm CMOS

A two-stage operational amplifier for biomedical applications is presented in this paper. In the Op-Amp design, all transistors have been operated in sub-threshold region for low voltage low power application. The proposed Op-Amp has been designed based on TSMC foundry 180nm process and simulated in Cadence analog design environment. The proposed circuit generates a 40dB gain, 114 KHz UGBW, 72 deg phase margin & total power consumption is just 112nW with 0.8V battery.

A Multiobjective Model for Energy Efficient QoS Provisioning Using Genetic Algorithm

In this paper, we investigate the problem of finding optimal path in a multicast tree that minimizes the energy consumption and also satisfies the quality-of-service (QoS) requirement of the application. Delay and packet loss probability are important QoS requirement for audio and video transmission. One approach for minimizing the energy consumption is power control. Transmission power control uses variable power to minimize the total transmitted power at the leaf nodes in the multicast tree. It has been established that that reducing the transmission power results in energy savings but increases the number of forwarding nodes in the tree. This may negatively impact the QoS requirement of the application. We model the issue as a multiobjective optimization problem to minimize the total energy consumption, delay and the packet loss in a multicast tree. We adapt the Elitist Non-Dominated Sorting Genetic Algorithm (NSGA - II) to find the Pareto front for the problem. The experimental results on the sample test network are presented to demonstrate the effectiveness of the proposed model.

Energy efficient QoS provisioning: A multi-colony ant algorithm approach.

With the advancement of technology, there is a growing desire to provide support for real time multimedia services over wireless ad hoc networks. These applications demand strict Quality-of-Service (QoS) guarantees by the underlying network in terms of delay, delay variance and packet loss. However, limited battery life of the nodes in a wireless network poses significant challenges in finding QoS optimized multicast routes. The depletion of energy resources of the node may lead to a disjoint network that can severely affect the QoS requirement of the application. In this paper, we investigate the problem of building a multicast tree that aims energy conservation while meeting the QoS demands of the application. We formulate the issue as a multiobjective optimization problem and apply a multi-colony ant approach to find the Pareto front for the new problem. The experimental results are presented to demonstrate the effectiveness of the algorithm. The results are compared with Elitist Non-dominated Sorting Genetic Algorithm (NSGA-II).