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Laser beam welding: research state of the art on performance and measures

Chandran Sudhin, Rajesh R., Devanand M.

Control and Cybernetics

2020

Vol. 49, No. 1

123--153

Laser beam welding (LBW) is a remarkable method for combining dissimilar materials, primarily when the unique amalgamation of metals is necessary. LBW, owing to attractive features, namely: low heat input, high heat concentration, high power density and low distortion is one of the more advantageous methods for, e.g., welding and repair of aircraft and turbine engine elements, constructed from superalloy. In this paper, the literature is scrutinized on diverse techniques that are associated with laser welding systems. The review is provided of several dozen research articles, involving an appropriate analysis. Initially, the analysis depicts various schemes that are contributed in different articles. Subsequently, the analysis also focuses on various particular features such as laser beam width and type of laser, and it also considers the heat treatment analysis that is contained in each of the articles reviewed. Furthermore, the present paper provides a detailed study regarding the performance measures and maximum performance achievements regarding each contribution accounted for. Finally, it indicates the various research issues, which can be useful for the researchers to carry out further research on laser welding systems. Of particular interest to the Readers of this journal is the fact of ample application of modelling, identification, data processing, image processing and AI tools in the respective surveyed studies.

Outage Performance of Bidirectional Full-Duplex Amplify-and-Forward Relay Network with Transmit Antenna Selection and Maximal Ratio Combining

Rajesh R., Velmurugan P. G. S., Thiruvengadam S. J., Mallick P. S.

Journal of Telecommunications and Information Technology

2018

nr 1

62--69

In this paper, a bidirectional full-duplex amplify- and-forward (AF) relay network with multiple antennas at source nodes is proposed. Assuming that the channel state information is known at the source nodes, transmit antenna selection and maximal ratio combining (MRC) are employed when source nodes transmit information to the relay node and receive information from the relay node respectively, in order to improve the overall signal-to-interference plus noise ratio (SINR). Analytical expressions are derived for tight upper bound SINR at the relay node and source nodes upon reception. Further, losed form expressions are also derived for end-to-end outage probability of the proposed bidirectional full-duplex AF relay network in the Nakagami-m fading channel environment. Although self-interference at the relay node limits the performance of the full-duplex network, the outage performance of the proposed network is better than that of conventional bidirectional full-duplex and half-duplex AF relay networks, due to the selection diversity gain in TAS and diversity and array gain in MRC.