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1

Optimization of a dual-slot waveguide for a refractive index biosensor

Sahu S., Ali J., Singh G.

Optica Applicata

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2018

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Vol. 48, nr 1

161--167

EN

The present article illustrates the modeling and optimization of a dual-slot waveguide for the application of a refractive index biosensor. The nanometer scale waveguide structure uses the silicon-on-insulator platform for the consideration of higher sensitivity and compactness of a resonator biosensor. The modal analysis is performed using the finite difference method based on full vector eigenmode calculation. The maximum field penetration in the lower index region is found for the quasi-TE mode. The sensitivity is maximized through the optimization of the waveguide dimension by relating effective refractive index with the dispersion of a waveguide. The biosensor showed the maximum calculated sensitivity of 461.327 nm/RIU and a limit-of-detection of 2.601 × 10–6 RIU (where RIU denotes refractive index unit).

2

Intelligent hybrid fuzzy logic system for damage detection of beam-like structural elements

Sahu S., Kumar P. B., Parhi D. R.

Journal of Theoretical and Applied Mechanics

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2017

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Vol. 55 nr 2

509--521

EN

Fuzzy logic has been used in different research fields for more than three decades. It has become a robust method to solve complex and intricate problems which are otherwise difficult to solve by traditional methods. But it still requires some human experience and knowledge. In the present study, an attempt is made to design a hybrid optimization technique for automatic formation of the fuzzy knowledge based rules using an evolutionary algorithm. This hybridization technique has been applied in the field of damage detection and location of cracks in cracked structural elements. In this paper, a robust fault diagnostic tool based on a differential evolution algorithm and fuzzy logic has been proposed. Theoretical and Finite Element analyzes are done to model the crack and to find the effect of the presence of cracks on changes of vibrational characteristic (natural frequencies) of a fixed-fixed beam. The inputs to DEA-FL system are the first three relative natural frequencies, and the outputs from the system are the relative crack depth and relative crack location. For the validation of the results obtained from the proposed method and to check the robustness of the controller, experimental analysis is performed. To find average error rates, the bootstrap method has been adopted.

3

Design and development of 3-stage determination of damage location using Mamdani-Adaptive Genetic-Sugeno model

Sahu S., Kumar P. B., Parhi D. R.

Journal of Theoretical and Applied Mechanics

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2017

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Vol. 55 nr 4

1325--1339

EN

Damage detection in structural elements like beams is one of important research areas for health monitoring. Initiation of a fault in the form of a crack or any damage puts a limitation on the service life of a structural member. So, in this paper, a method is proposed which uses the advantages of soft computing techniques like Fuzzy Inference Systems (Mamdani and Sugeno) and Adaptive Genetic Algorithm for three stage refinement of the data base generated using dynamic responses from a cracked fixed-free aluminum alloy beam element. For the crack element reference, a finite element model of a single transverse crack has been considered. The proposed method describes both Mamdani and Sugeno Fuzzy Inference Systems for training of damage parameters. In the Adaptive Genetic Algorithm, a statistics based method has been incorporated to limit the randomness of the search process. Finally, the results from the Mamdani-Adaptive Genetic-Sugeno model (MAS) are validated with the results from the experimental analysis.

4

Cardiovascular Load During Summer Work of Two Age Groups of Van-Rickshaw Pullers in West Bengal, India

Sahu S., Maity S. G., Moitra S., Sett M., Haldar P.

International Journal of Occupational Safety and Ergonomics

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2013

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Vol. 19, No. 4

657--665

EN

Van-rickshaw is a popular mode of transport of people and merchandise in developing countries. The purposeof this study was to assess the effect of age on cardiovascular load of van-rickshaw pullers in the summer season (March–June) in real situations. In 142 participants, divided into 2 age groups (25–40 and 41–55 years), cardiovascular load was assessed on the basis of working and partial recovery heart rate (HR), predicted maximal HR, working maximal HR, average working HR, percentage of reserved HR, sum of recovery heart beats, percentage of recovery, relative and net cardiac cost, etc. Except for percentage of recovery, all parameters differed significantly between the groups and were significantly correlated with age. As this activity is very stressful, it places a heavy demand on the cardiovascular system. Therefore, age is an important factor for sustainability of the work, especially in a hot environment. Some ergonomic interventions are necessary to reduce cardiovascular load.

5

A Comparative Ergonomics Postural Assessment of Potters and Sculptors in the Unorganized Sector in West Bengal, India

Sahu S., Moitra S., Maity S., Pandit A. K., Roy B.

International Journal of Occupational Safety and Ergonomics

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2013

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Vol. 19, No. 3

455--462

EN

Potters and sculptors perform their work in very awkward postures. The purpose of this study was to analyse these postures. The modified Nordic questionnaire was used to analyse musculoskeletal discomfort. Rapid entire body assessment (REBA) and rapid upper limb assessment (RULA) were used to evaluate the subjects' postures. There were no significant differences between times of discomfort and the group of subjects. However, there were significant differences in discomfort in different body parts. The analysis indicated that various body postures were harmful to the subjects and that there were profound deviations from natural curvature of various body parts due to awkward body postures. Ergonomics intervention was required to improve the quality of life.