K. Murali

Bio: K. Murali is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Breakwater & Finite element method. The author has an hindex of 14, co-authored 73 publications receiving 700 citations. Previous affiliations of K. Murali include Swansea University & Institute of High Performance Computing Singapore.

Study on Maintenance Dredging for Navigable Depth Assurance in the Macro-tidal Hooghly Estuary

Abstract: Hooghly Estuary is a tide-dominated estuary in the east coast of India, experiencing heavy siltation in the navigation channel. This frequent siltation affects the movement of vessels, thus, hampering the efficiency of the port. The quantity of siltation is related to the physical and environmental conditions and the geometric configuration of the entrance as well as the navigation channels. This study aims at investigating the possibility of smooth navigable channel to the Haldia Dock Complex with a minimum quantity of maintenance dredging. The monitoring of the channel through bathymetry survey at regular intervals has been carried out. The filed survey involved identification of the zones of siltation, changes in the depth and estimation of sediment volumes at 10 different sections along the Eden bar. It was found in the study that the siltation depth varies between the spring and neap tide periods due to the variation in the tidal currents. From the field monitoring surveys, it is found that there is predominant erosion from neap-to-spring tidal cycle. These aspects are brought out in the manuscript along with the stability details of the Eden channel, throughout the year.

Keratoconus Classifier for Smartphone-based Corneal Topographer

Abstract: Keratoconus is a severe eye disease that leads to deformation of the cornea. It impacts people aged 10–25 years and is the leading cause of blindness in that demography. Corneal topography is the gold standard for keratoconus diag-nosis. It is a non-invasive process performed using expensive and bulky medical devices called corneal topographers. This makes it inaccessible to large populations, especially in the Global South. Low-cost smartphone-based corneal topographers, such as SmartKC, have been proposed to make keratoconus diagnosis accessible. Similar to medical-grade topographers, SmartKC outputs curvature heatmaps and quantitative metrics that need to be evaluated by doctors for keratoconus diagnosis. An auto-matic scheme for evaluation of these heatmaps and quantitative values can play a crucial role in screening keratoconus in areas where doctors are not available. In this work, we propose a dual-head convolutional neural network (CNN) for classifying keratoconus on the heatmaps generated by SmartKC. Since SmartKC is a new device and only had a small dataset (114 sam-ples), we developed a 2-stage transfer learning strategy-using historical data collected from a medical-grade topographer and a subset of SmartKC data-to satisfactorily train our network. This, combined with our domain-specific data augmentations, achieved a sensitivity of 91.3% and a specificity of 94.2%.

Impact of Ship-Generated Waves on the Sediment Resuspension in Restricted Waterways

Abstract: The ship-generated waves in restricted waterways can influence the behavior of sediment resuspension and bank erosion. This paper explores the case study considering the effect of ship-generated waves in restricted channels. A fully nonlinear Boussinesq model (FUNWAVE-TVD) is used to simulate the ship-generated waves. The sediment transport model adopted in FUNWAVE has been changed to incorporate the modified diffusion coefficients, deposition flux, and an explicit equation for settling velocity and critical shield parameter. The sediment transport model was validated against the experimental results of solitary waves in a wave tank, and model performance in shoreline geometry was reported. The implementation of the moving vessel in the numerical model and its impact on suspended sediment concentration were evaluated against the field measurements in the Falta stretch of the Hooghly river in Indian National Waterway 1. The error value in predicting the depth-averaged suspended sediment concentration by the FUNWAVE module was 97.6%, which has been significantly reduced to 16.3% based on the present modification. The parametric study of the ship waves in a typical restricted waterway of India revealed that the concentration of the sediments gradually decreases from the navigation channel to the river banks due to dissipation in the ship waves. The change in wave height and depth-averaged sediment concentration increases with the increasing depth Froude number. Finally, the impact on sediment transport due to different scenarios, such as the movement of two vessels in close proximity, the passage of vehicles coming from the opposite direction on the navigation channel, the influence of small draft vessels, and the bed morphology changes due to the multiple vessel movements are analyzed and reported.

Sri Lanka Field Survey after the December 2004 Indian Ocean Tsunami

Abstract: In August 2005, a team surveyed the effects of the December 2004 Indian Ocean tsunami on the southern coast of Oman. Runup and inundation were obtained at 41 sites, extending over a total of 750 km of shoreline. Measured runup ranged from 3.25 m in the vicinity of Salalah to a negligible value at one location on Masirah Island. In general, the largest values were found in the western part of the surveyed area. Significant incidents were documented in the port of Salalah, where a 285-m-long vessel broke its moorings and drifted inside and outside the port, and another ship struck the breakwater while attempting to enter the harbor. The general hazard to Oman from tsunamis may be greatest from the neighboring Makran subduction zone in western Pakistan.