NOPR Collection:

Hydrodynamic and Advection-Dispersion Simulation of Cool Seawater Discharges from an LNG Facility

2020-01-01T00:00:00Z

Title: Hydrodynamic and Advection-Dispersion Simulation of Cool Seawater Discharges from an LNG Facility Authors: Gupta, Ankit; Vijay, Ritesh; Kumar, Rakesh Abstract: The impact of cool seawater discharge in the coastal waters from a Liquefied Natural Gas (LNG) plant has been simulated using MIKE21. In this work, hydrodynamics conditions of the coastal waters were calibrated and corroborated to predict the cool seawater discharge under two plant design scenarios by selecting flow rate 15 m3/s and 10 m3/s with a temperature drop of 5 °C and 7 °C, respectively. The simulations were carried out under different scenarios, to arrive at the best possible case to minimize the potential impact on the coastal environment. Both the simulated scenarios complied with the available World Bank guidelines for LNG facilities. However, the designed scenario of flow rate 10 m3/s with a temperature drop of 7 °C between inlet and outlet presents a better choice as it reduces the pumping power of seawater intake. As there are no Indian guidelines for cool seawater discharges from LNG plant, the present work can support the policymakers and regulators to formulate coherent discharge standards. Page(s): 7-14

Statistical Studies on Rainfall and Time-based Deviations in Precipitation Trends in Vaigai River Basin, TN State, India

2020-01-01T00:00:00Z

Title: Statistical Studies on Rainfall and Time-based Deviations in Precipitation Trends in Vaigai River Basin, TN State, India Authors: Palanichamy, Mahadevan; Sankaralingam, Ramaswamy; Narayanasamy Abstract: Food shortage and water shortage remains the most critical issues throughout the world. Understanding the variability in rainfall will help to make predictions about the rainfall patterns as well as addressing the issues of food-water-energy nexus. Herein, a trend analysis of rainfall was carried out in selected seven rainfall stations of Vaigai river basin in Tamil Nadu state, India. Statistical trend analysis was carried out, to observe the trend pattern for the period from 1959 to 2016. To determine the trend of rainfall, non-parametric Mann-Kendall test and Spearman Rho tests were used. This investigation provides insights about precipitation trends during annual, post-monsoon, pre-monsoon periods. These findings will provide clues for developing efficient water management systems using different simulation techniques and artificial intelligence approaches. Page(s): 15-23

Variation of hydrochemical parameters with reference to geomorphological features in Godavari estuary, India

2020-01-01T00:00:00Z

Title: Variation of hydrochemical parameters with reference to geomorphological features in Godavari estuary, India Authors: Chari, N.V.H.K.; Venkateswararao, Ch.; Muralikrishna, R.; Sivakrishna, K. Abstract: In this study, seasonal observations of hydrochemical parameters were measured in the estuarine regions of Gautami Godavari (GGE) and Vasishta Godavari (VGE), which are surrounded by extensive mangrove swamps and closely spaced beach ridge-swale complex, respectively. A significant vertical stratification in the water column showed in the VGE region due to the strong influence of saline water intrusion. NO₂^- -N was higher and NO₃^- -N was lower in VGE during the end of the post monsoon season with reference to excretion by phytoplankton and uptake during the process of primary production respectively, which is also supported by higher concentrations of Chlorophyll a. Nutrients (NO₃^- -N, PO₄^3—P and SiO₄^2--Si) showed conservative behaviour with salinity in GGE, whereas, in the case of VGE absence of this is due to intrusion of saline water was significantly higher. Page(s): 24-33

A new method for detecting line spectrum of ship-radiated noise based on a new double duffing oscillator differential system

2020-01-01T00:00:00Z

Title: A new method for detecting line spectrum of ship-radiated noise based on a new double duffing oscillator differential system Authors: Li, Guohui; Zhao, Ke; Yang, Hong Abstract: In order to detect line spectrum of ship-radiated noise under the ocean background noise and improve the method of detecting duffing oscillator intermittent chaos, a method of detecting intermittent chaos based on variable step size dual duffing oscillator differential system is proposed. Based on the duffing oscillator, two independent and incompletely coupled duffing oscillators can be differentiated based on the differential principle by using the proposed method, which reduces the computational complexity and makes the timing diagram more intuitive. In order to further improve the detection efficiency and reduce the computational complexity of the system, the author put forward that a sequence of solving steps can be built by using only one duffing oscillator and the method of detecting the unknown frequency signal can be achieved by changing the step size of the system. Simulation results show that compared with the conventional duffing oscillator detection method, the proposed method has improved the SNR (signal-to-noise ratio) by at least 10.6 dB. Comparing with duffing system chaotic oscillator column and double duffing system chaotic oscillator column detection method, the proposed method is most effective in detecting line spectrum of ship-radiated noise. Page(s): 34-43