G.S.Sanyal School of Telecommunication

This paper presents an improved particle swarm optimizer (PSO) for solving multimodal optimization problems with problem-specific constraints and mixed variables. The standard PSO is extended by employing a comprehensive learning strategy, different particle updating approaches, and a feasibility-based rule method. The experiment results show the algorithm located the global optima in all tested problems, and even found a better solution than those previously reported in the literature. In some cases, it outperforms other methods in terms of both solution accuracy and computational cost.

One of the main attractions of a fuzzy rule-based system is its interpretability which is hindered severely with an increase in the dimensionality of the data. For high-dimensional data, the identification of fuzzy rules also possesses a big challenge. Feature selection methods often ignore the subtle nonlinear interaction that the features and the learning system can have. To address this problem of structure identification, we propose an integrated method that can find the bad features simultaneously when finding the rules from data for Takagi-Sugeno-type fuzzy systems. It is an integrated learning mechanism that can take into account the nonlinear interactions that may be present between features and between features and fuzzy rule-based systems. Hence, it can pick up a small set of useful features and generate useful rules for the problem at hand. Such an approach is computationally very attractive because it is not iterative in nature like the forward or backward selection approaches. The effectiveness of the proposed approach is demonstrated on four function-approximation-type well-studied problems.

In this paper we examine the effect of relay (R) placement on the energy efficiency of a wireless sensor network (WSN) operating over a η-μ fading channel. We consider η-μ statistics for modeling the small scale fading affected wireless channel between the sensor nodes as the η-μ model is quite general in nature and it encompasses other popular fading models such as Rayleigh, Nakagami etc. In order to address the demand for high data rate WSN applications, spectrally efficient M-ary quadrature amplitude modulation (MQAM) is adopted. Transmission between a pair of sensor nodes is benefitted from a third node, placed in a collinear manner (i.e. on the same straight line, joining source and destination) between source (S) and destination (D), and acting as a relay (R). The relay operates in a selective decode and forward (DF) mode. It has been seen that it is more beneficial to place the R closer to S than D. We have also investigated the effective relay placement region and how different design parameters such as constellation size (M), path loss exponent (n) and fading parameters (η and μ) affect the placement region.

IEEE 802.15.4 has emerged as a popular standard for short range wireless sensor networks used in industrial, military, health, and environmental sectors. The limited lifetime of such networks is one of the critical design challenges. This paper examines the how relaying through intermediate sensor nodes can enhance the lifetime of an 802.15.4 network. In particular, novel energy consumption models for both AF and DF relays have been developed. Different relay gain scaling mechanisms and forwarding strategies under each of the relay categories were also considered and their energy efficiencies were compared. For every relaying protocol, it was found that there exists an optimum location where energy saving is maximum and this location is not necessarily different for different modes. In summary, it has been observed that the optimum location for AF relays is the equidistant point from source and destination. In contrast, the optimal location for DF relays is closer to source. The effect of different PHY level (outage probability, path loss) and MAC level parameters (frame length) on the energy efficiency are also studied.

Objectives: This paper presents the design aspects and simulation of a right-hand circularly polarized, dual-band, two layer stacked micro-strip antenna for IRNSS receiver front-end operating at L5 band (1176.45 MHz) and S band (2492.028 MHz) frequencies. Methods: IRNSS satellites transmit navigational signals in L5 (1176.45 MHz) and S (2492.028 MHz) frequency bands. Dual-band antenna is preferred to mitigate the effect of Ionosphere on the IRNSS signal. Two layer stacked patch structure is adopted for the proposed antenna with the bottom patch designed for L5 band and top patch for S band. Right-Hand Circularly Polarized operation with Axial Ratio less than 2dB is achieved by introducing a pair of square shaped notches at the diagonally opposite sides of 1 International Journal of Pure and Applied Mathematics Volume 118 No. 17 2018, 47-59 ISSN: 1311-8080 (printed version); ISSN: 1314-3395 (on-line version) url: http://www.ijpam.eu Special Issue ijpam.eu

In order to observe severe weather conditions during cyclones, thunderstorms, etc., IMAGER instruments on-board INSAT3D/3DR have been built with a flexible scanning feature known as 'rapid scan mode'. Using this feature, the number of scan lines over a given coverage region and the number of repetitions of the selected region can be programmed for scanning. Therefore, to understand the physical processes involved in convective clouds associated with severe weather phenomena, rapid scan of INSAT3DR mode is attempted. It has very high temporal resolution of approximately 4 min and 30 sec. The present study will help in better understanding of the physical processes of severe weather phenomena and in nowcasting. It will also help to improve the accuracy in the NWP model forecast through assimilation of radiances and atmospheric motion wind determined using rapid scan mode.