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Amiya Gayen,Sunil Saha 대한공간정보학회 2018 Spatial Information Research Vol.26 No.1
Deforestation threatens biodiversity in remaining forest in India. Today majority of populated areas are facing huge anthropogenic deforestation and it is one of the greatest problems in our country. For the sustainable management of forest there is a need of prediction about the probability of deforestation, i.e. which areas are most susceptibility to deforestation. This study reveals a methodology for predicting the areas of deforestation based on cultural and natural landscape. Geographical information system and logistic regression have been used to predict the greatest propensity for the deforestation of Pathro river basin. The logistic regression model has proven that the deforestation is an integrated function of altitude, slope, slope aspect, distance from road, settlement, river and forest edge. The independent variables are strongly correlated with deforestation. Finally, the receiver operating characteristic curve has been drawn for the validation of deforestation probability map and the area under the curve (AUC) is commuted for verification and measurement of level of accuracy. The AUC for the logistic regression model has shown 76.6% prediction accuracy. The result reveals that the performance logistic regression is good enough in simulation of deforestation process. This model also predicted the areas with high potential for future deforestation.
Sanjib Gayen,Sri Harsha Kombathula,Sumanta Manna,Sonal Varshney,Puneet Pareek 대한방사선종양학회 2020 Radiation Oncology Journal Vol.38 No.2
Purpose: To evaluate the dosimetric variations in patients of head and neck cancer treated with definitive or adjuvant radiotherapy using optimized non-coplanar (ncVMAT) beams with coplanar (cVMAT) beams using volumetric arc therapy. Materials and Methods: Twenty-two patients of head and neck cancer that had received radiotherapy using VMAT in our department were retrospectively analyzed. Each of the patients was planned using coplanar and non-coplanar orientations using an optimized couch angle and fluences. We analyzed the Conformity Index (CIRTOG), Dose Homogeneity Index (DHI), Heterogeneity Index (HIRTOG), low dose volume, target and organs-at-risk coverage in both the plans without changing planning optimization parameters. Results: The prescription dose ranged from 60 Gy to 70 Gy. Using ncVMAT, CIRTOG, DHI and HIRTOG, and tumor coverage (ID95%) had improved, low dose spillage volume in the body V5Gy was increased and V10Gy was reduced. Integral dose and intensity-modulated radiation therapy factor had increased in ncVMAT. In the case of non-coplanar beam arrangements, maximum dose (Dmax) of right and left humeral head were reduced significantly whereas apex of the right and left lung mean dose were increased. Conclusion: The use of ncVMAT produced better target coverage and sparing of the shoulder and soft tissue of the neck as well as the critical organ compared with the cVMAT in patients of head and neck malignancy.
Roy, Amitava,Suneel, G.,Gayen, J.K.,Ravi, K.V.,Grover, R.B. Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.10
The key process used in nuclear industries for the management of radiotoxicity associated with spent fuel in a closed fuel cycle is solvent extraction. An understanding of hydrodynamics and mass transfer is of primary importance for the design of mass transfer equipment used in solvent extraction processes. Understanding the interfacial phenomenon and the associated hydrodynamics of the liquid drops is essential for model-based design of mass transfer devices. In this work, the phenomenon of drop formation at the tip of a nozzle submerged in quiescent immiscible liquid phase is revisited. Previously reported force balance based models and empirical correlations are analyzed. Experiments are carried out to capture the process of drop formation using high-speed imaging technique. The images are digitally processed to measure the average drop diameter. A correlation based on the force balance model is proposed to estimate drop diameter and jet length. The average drop diameter obtained from the proposed model is in good agreement with experimental data with an average error of 6.3%. The developed model is applicable in both the necking as well as jetting regime and is validated for liquid-liquid systems having low, moderate and high interfacial tension.
Temperature-dependent Scaling Behavior of Magnetic Hysteresis Loop of CoFeB/Pd Multilayer Film
Nguyen Le Thi,Anabil Gayen,Yunxiu Zhao,Jae-Hyun Ha,Jung-Il Hong,Dong-Hyun Kim 한국자기학회 2022 Journal of Magnetics Vol.27 No.4
We report our experimental investigation on the temperature-dependent hysteresis loops and magnetic domain behaviors of CoFeB (0.4 nm)/Pd (1 nm) multilayer on polyimide substrate with a perpendicular magnetic anisotropy, by means of magneto-optical Kerr microscopy. Hysteresis characteristics such as saturation magnetization, coercivity, and hysteresis loop area with respect to the temperature have been analyzed, where powerlaw scaling behaviors are observed with microscopic magnetic domain patterns mediated by numerous nucleation sites.
G. Suneel,S. Rajasekaran,J. Selvakumar,Chetan P. Kaushik,J.K. Gayen,K.V. Ravi 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.3
Vitrification of radioactive liquid waste (RLW) provides a feasible solution for isolating radionuclidesfrom the biosphere for an extended period. In vitrification, base glass and radioactive waste are addedsimultaneously into the melter. Determination of heat and mass transfer rates is necessary for rationaldesign and sizing of melter. For obtaining an assured product quality, knowledge of reaction kineticsassociated with the thermal decomposition of waste constituents is essential. In this study Thermogravimetry(TG) - Differential Thermogravimetry (DTG) of eight kinds of nitrates and two oxides, whichare major components of RLW, is investigated in the temperature range of 298e1273 K in the presence ofbase glasses of five component (5C) and seven component (7C). Studies on thermal behavior of constituentsin RLW were carried out at heating rates ranging from 10 to 40 K min 1 using TG e DTG. Thermal behavior and related kinetic parameters of waste constituents, in the presence of 5C and 7C baseglass compositions were also investigated. The activation energy, pre-exponential factor and order of thereaction for the thermal decomposition of 24% waste oxide loaded glasses were estimated using Kissingermethod
RADAR level measurement in Joule heated ceramic melter: A novel technique
Suneel, G.,Mahashabde, Mukesh,Borkotoky, Ritusmita,Sharma, Nitin Kumar,Pradeep, M.P.,Gayen, J.K.,Pimparkar, H.R.,Ravi, K.V. Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.4
The current study relates to RADAR (RAdio Detection and Ranging) application for level measurement of vitrified radioactive liquid nuclear waste. The vitrification of radioactive liquid waste is carried out in special equipment called 'Melters'. The study is directed towards the design and frequency modulation used in the level measurement of vitrified waste. More specifically, the RADAR design and frequency used for level measurement in a melter. This level measurement technique can also be used for dynamic vitrification process and can be used to measure the level variations without using any external medium/material and using only electromagnetic waves. Also, this technique is durable and accurate even under the high radioactive environment present inside the melter.
Manas Mandal,Krishna Chattopadhyay,Malay Chakraborty,Wonjae Shin,Kamal Kanti Bera,Sujit Chatterjee,Akbar Hossain,Dipanwita Majumdar,Arup Gayen,Changwoon Nah,Swapan Kumar Bhattacharya 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.6
A negative electrode is constructed based on MnSn(OH)6 nanocubes prepared by a simple precipitation method at roomtemperature for supercapacitor application. The as-prepared material was structurally and morphologically characterizedwith the help of XRD, FT-IR, Raman, XPS, FESEM, and HRTEM analyses. The uniform structure and fine edge morphologywith high conductivity due to oxygen vacancies promote the redox reaction, which results in high pseudocapacitance. Theelectrochemical performance is investigated through a three-electrode cell system in a negative potential window (− 1.0 to0.0 V). A maximum specific capacitance of 209 F/g is calculated at a specific current of 1 A/g. The electrodes also exhibitexcellent cycling stability (79% specific capacitance retention after 3000 consecutive GCD cycles).