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From source to emplacement:The origin of leucogranites from the Sikkim-Darjeeling Himalayas,India

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Geoscience Frontiers 2024年第1期15卷 384-401页

作者： Tanya Srivastava Nigel Harris Catherine Mottram Kumar Batuk Joshi Nishchal Wanjari Department of Geology Sikkim UniversityGangtokIndia School of Environment Earth&Ecosystem SciencesOpen UniversityMiltonKeynesUK School of the Environment Geography and GeosciencesUniversity of PortsmouthUK National Centre for Earth Science Studies ThiruvananthapuramKeralaIndia

Himalayan leucogranites are important for understanding the tectonic evolution of collision zones in general and the causes of crustal melting in the Himalayan orogen in particular.This paper aims to understand the melt source and emplacement age of the leucogranites from Sikkim in order to decipher the deep geodynamic processes of the eastern Himalayas.Zircon U-Pb analysis of the Higher Himalayan Sequence(HHS)metamorphic core reveals a prolonged period of crustal melting between>33 Ma and ca.14 Ma.Major and trace element abundances are presented for 27 leucogranites from North Sikkim that are classified into two-mica and tourmaline leucogranite types.They are peraluminous in composition,characterized by high SiO2(70.91-74.9 wt.%),Al2O3(13.69-15.82 wt.%),and low MgO(0.13-0.74 wt.%).Elemental abundances suggest that Sikkim Himalayan leucogranites are derived from crustal melts.The two-mica leucogranites are derived from a metagreywacke source,whereas the tourmaline leucogranites are sourced from metapelitic sources,with inherited zircons indicating an HHS origin for both types.U-Pb zircon geochronology of the two mica leucogranites indicates ages of ca.19-15 Ma,consistent with crustal melting recorded in HHS gneisses from Darjeeling.Monazites from both the two-mica and tourmaline leucogranites yield a crystallization age of ca.15-14 Ma,coeval with movement on the Main Central Thrust and South Tibetan Detachment System which further provides constraints on the timing and mechanism of petrogenesis of leucogranites in the Sikkim Himalayas.

关键词： Leucogranites Gneiss U-Pb geochronology Zircon Monazite Sikkim-Darjeeling Himalayas

Fluoride contamination in groundwater:A global review of the status,processes,challenges,and remedial measures

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Geoscience Frontiers 2024年第2期15卷 1-29页

作者： E.Shaji K.V.Sarath M.Santosh P.K.Krishnaprasad B.K.Arya Manisha S.Babu Department of Geology University of KeralaKariavattom CampusThiruvananthapuramKerala 695581India School of Earth Sciences and Resources China University of Geosciences(Beijing)29 Xueyuan RoadBeijing 100083China Department of Earth Science University of AdelaideAdelaideSA 5005Australia Department of Geology Central University of KeralaTejaswini HillsPeriyeKasaragodKerala 671316India

Groundwater pollution by fluoride is one of the prime concerns of the world population due to its toxicity,which results in adverse health impacts.In this paper,we review the current scenario of the fluoride contamination of groundwater in various countries across the globe and its impact on human health.During the last decade,several newly affected regions have been reported all over the world,with more than 100 countries affected by fluoride contamination in groundwater(concentration exceeding the acceptable limit of 1.5 mg/L defined by the World Health Organization).Fluoride poisoning is mainly due to the unsupervised ingestion of products for dental and oral hygiene and over-fluoridated drinking water.It is estimated that more than 200 million people from different countries are affected by fluoriderelated groundwater issues and health problems.The highest among these are from the countries in Africa(38),Asia(28),and Europe(24),followed by countries like South America(5),North America(3),and Australia(2).The source of fluoride in drinking water is primarily geogenic,together with forage,grasses and grains,tea,and anthropogenic sources.These countries affected were correlated with climatic zones and geological factors to gain insights into geospatial relations.Our analyses show that most of the fluoride pollution-prone zones are located in high-grade metamorphic terranes with granitoid or alkaline intrusions,geothermal hot springs,and volcanic regions with arid or semi-arid climatic conditions.This study also finds that children across the globe are more vulnerable than adults to fluoride contamination.The review finds that,although there are efficient fluoride removal techniques,including filters with next-generation nanomaterials,to date,there has not been a single technique developed that can claim to be a practically robust solution for fluoride removal from drinking water.Therefore,we suggest developing next-generation filters that can retain essential minerals in water and remove only harmful ones and se

关键词： Fluoride Groundwater Water contamination WHO standards Climate zones Remediation Sustainable Development Goals

Physico-mechanical characteristics of bast fibres of Sesamum indicum and Sesamum radiatum for bioprospecting

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Journal of Bioresources and Bioproducts 2022年第4期7卷 306-319页

作者： Ancy S Watson Suhara Beevy S Department of Botany University of KeralaThiruvananthapuram 695581KeralaIndia

Natural fibres are renewable,inexpensive and biodegradable sources of sustainable materials from plants or animals.Bast fibres,as the notable natural fibres,are gathered from the outer cell layers of the stem of plant.Mature and young bast fibres from two species of Sesamum,namely Sesamum indicum L.and S.radiatum Schumach.&Thonn.were extracted through traditional water retting technique and analyzed for their physical,mechanical and chemical attributes.Anatomical studies revealed polygon shaped phloem(bast fibre)cells with small lumen were similar to jute,in terms of architecture,and bagasse,in terms of lumen size.Upon extraction and subsequent drying,the young stems of S.radiatum were found to yield more bast fibres by mass compared with the rest of the Sesamum samples,that was,0.59 g(dry weight)of bast fibres from 100 g(fresh weight)of stem.According to stereo microscopic images,the mature S.radiatum fibres had rougher edges than the rest.Both S.indicum and S.radiatum fibre surfaces also seemed to have pores,according to scanning electron microscopy(SEM)images.The porosity appeared to get more pronounced as the plants got older.The Sesamum bast fibres were also found to be extremely hydrophilic with a high-water retention value.The fibres obtained from S.radiatum were determined to be suitable for the textile industry due to their light colour,ideal diameter and length,and water-holding capacity that matched the requirements of fabric manufacturing.Even in the absence of a mordant,the mature fibres showed a significant degree and evenness of Alizarin dye attachment,which might be correlated to the increase in fibre surface roughness with fibre maturity.These fibres were also discovered to be comparable with jute in terms of phloem cell shape(polygonal),diameter(13-15 m),tenacity(12.86-32.54 gf/(g·km-1)),and linear density(2.5-3.3 g/km).It suggested that they might find industrial applications if further research were to be done.

关键词： Sesamum Bast fibre Textile Tensile strength Dyeing Sustainability

Robust Machine Learning Technique to Classify COVID-19 Using Fusion of Texture and Vesselness of X-Ray Images

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Computer Modeling in Engineering & Sciences 2024年第2期138卷 1981-2004页

作者： Shaik Mahaboob Basha Victor Hugo Cde Albuquerque Samia Allaoua Chelloug Mohamed Abd Elaziz Shaik Hashmitha Mohisin Suhail Parvaze Pathan Department of Electronics and Communication Engineering N.B.K.R.Institute of Science&TechnologyVidyanagarAndhra Pradesh524413India Department of Teleinformatics Engineering Federal University of CearáFortaleza60455-970Brazil Information Technology Department College of Computer and Information SciencesPrincess Nourah bint Abdulrahman UniversityRiyadh84428Saudi Arabia Department of Mathematics Faculty of ScienceZagazig UniversityZagazig44519Egypt Faculty of Computer Science and Engineering Galala UniversitySuez435611Egypt Artificial Intelligence Research Center(AIRC) College of Engineering and Information TechnologyAjman UniversityAjmanUnited Arab Emirates Department of Electrical and Computer Engineering Lebanese American UniversityByblos13-5053Lebanon Department of Avionics Indian Institute of Space Science and TechnologyThiruvananthapuramKerala695547India Department of Veterinary Clinical Sciences University of MinnesotaSt.PaulMinnesota55108USA

Manual investigation of chest radiography(CXR)images by physicians is crucial for effective decision-making in COVID-19 diagnosis.However,the high demand during the pandemic necessitates auxiliary help through image analysis and machine learning techniques.This study presents a multi-threshold-based segmentation technique to probe high pixel intensity regions in CXR images of various pathologies,including normal cases.Texture information is extracted using gray co-occurrence matrix(GLCM)-based features,while vessel-like features are obtained using Frangi,Sato,and Meijering filters.Machine learning models employing Decision Tree(DT)and RandomForest(RF)approaches are designed to categorize CXR images into common lung infections,lung opacity(LO),COVID-19,and viral pneumonia(VP).The results demonstrate that the fusion of texture and vesselbased features provides an effective ML model for aiding diagnosis.The ML model validation using performance measures,including an accuracy of approximately 91.8%with an RF-based classifier,supports the usefulness of the feature set and classifier model in categorizing the four different pathologies.Furthermore,the study investigates the importance of the devised features in identifying the underlying pathology and incorporates histogrambased analysis.This analysis reveals varying natural pixel distributions in CXR images belonging to the normal,COVID-19,LO,and VP groups,motivating the incorporation of additional features such as mean,standard deviation,skewness,and percentile based on the filtered images.Notably,the study achieves a considerable improvement in categorizing COVID-19 from LO,with a true positive rate of 97%,further substantiating the effectiveness of the methodology implemented.

关键词： Chest radiography(CXR)image COVID-19 classifier machine learning random forest texture analysis

Effects of multiple subcavities with floor subcavity in supersonic cavity flow

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Propulsion and Power Research 2023年第1期12卷 114-137页

作者： Priyansh Jain Anbarasan Sekar Aravind Vaidyanathan Indian Institute of Space Science and Technology ThiruvananthapuramKerala 695547India

Experimental and computational analysis has been carried out by many researchers on supersonic cavity flow,but detailed analysis based on Rossiter’s model still requires some insight.In the current study an open rectangular cavity with a length to depth ratio of 2(L/D=2)and Mach number at the inlet as 1.71,was considered as a baseline configuration for experimental analysis.Statistical techniques such as power spectral density(PSD),correlation,and overall sound pressure level(OASPL)were carried out on the unsteady pressure data,to analyze the aero-acoustic flow physics.High-speed schlieren images were processed to obtain spatially coherent modes by proper orthogonal decomposition(POD).The analysis was extended for different dimensions of subcavities on the aft,floor,and front wall.This detailed analysis of these configurations with different dimensions and combinations revealed the various flow features and mode frequencies in supersonic cavity.As the front wall subcavity act as a passive control device,reducing the overall sound pressure level inside the cavity whereas,the aft wall subcavity acts as a passive resonator with distinct harmonic fluidresonant modes,a similar phenomenon was observed for floor subcavity at different locations.A novel method was employed to analyze Rossiter’s model and its applicability in estimating experimental modes was verified,as it accurately predicted the dominant frequencies with a maximum of 2.74% uncertainty among all the configurations.

关键词： Supersonic cavity flow Fast Fourier transform High speed schlieren Proper orthogonal decomposition Rossiter’s feedback mechanism

Hydrocarbon fluid inclusions and source rock parameters:A comparison from two dry wells in the western offshore,India

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Geoscience Frontiers 2023年第1期14卷 64-78页

作者： Silpa Thankan V.Nandakumar S.Shivapriya National Facility for Geofluids Research and Raman Analysis National Centre for Earth Science StudiesMinistry of Earth SciencesGovernment of IndiaThiruvananthapuram 695011KeralaIndia Department of Geology University of KeralaThiruvananthapuram 695581KeralaIndia

Fluid inclusions represent the direct evidence of paleofluids and can provide valuable information on the evolution of sedimentary basins and oil-bearing strata.Hydrocarbon fluid inclusion(s)(HCFIs)are the vestiges of oil from the geological formations.The paper delineates the paleotemperature(T_(h))/oil window,the oil quality of HCFIs and Raman peaks corresponding to hydrocarbon species of HCFIs using fluid inclusion techniques,and source rock potential of hydrocarbon generation,thermal maturity,the quantity of organic matter,and the kerogen types obtained through Rock-Eval pyrolysis data from two dry wells RV-1 well of Mumbai offshore and KKD-1A well of Kerala-Konkan Basin.The present study compares the fluid inclusion parameters as well as the source rock geochemical characteristics of these two dry wells to address the scientific problem of the wells going dry.Further,evaluated whether the results agree with an earlier finding from a case study of two wells named KK4C-Al(Kerala-Konkan basin)and RV-1 well where only a few parameters such as temperature of homogenization(T_(h))&API gravity were utilised,and the chances of getting oil in the nearby areas of these two wells were reported.In the present study,the fluid inclusion parameters such as the palaeotemperature(T_(h)),API Gravity and Raman spectra were obtained from micron sized fluid inclusions at different depths for a quick assessment of nature of oil inclusions within the two dry wells.Along with fluid inclusion parameters,different source rock parameters obtained from Rock-Eval Pyrolysis analysis(secondary data)such as S1,S2,S3,(T_(max)),Hydrogen Index(HI),Oxygen Index(OI),Potential Yield(PY),Production Index(PI)and Total Organic Carbon Content(TOC)were also considered for a detailed source-rock evaluation of two wells(RV-1 and KKD-1A)and the results act as the supporting evidence to address the reason for the wells gone dry.Temperature of homogenisation(T_(h))of hydrocarbon Fluid Inclusion Assemblages(FIAs)from both the wells fall in the oil window(6

关键词： Hydrocarbon fluid inclusions(HCFIs) Spectroscopic analysis Oil window API gravity Rock-Eval pyrolysis

Statistical optimization and formulation of microalga cultivation medium for improved omega 3 fatty acid production

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Systems Microbiology and Biomanufacturing 2022年第2期2卷 369-379页

作者： Aswathy Udayan Nidhin Sreekumar Muthu Arumugam Microbial Processes and Technology Division National Institute for Interdisciplinary Science and Technology(NIIST)CSIRIndustrial EstatePappanamcodeThiruvananthapuramKerala 695019India Academy of Scientifc and Innovative Research(AcSIR) Ghaziabad 201002India Accubits Invent Accubits Technologies Inc.ThiruvananthapuramKerala 695004India

Microalgae are considered a rich source of high-value metabolites with an array of nutraceutical and pharmaceutical applications.Diferent strategies have been developed for cultivating microalgae at large-scale photobioreactors but high cost and low productivity are the major hurdles.Optimizing the composition of media for the cultivation of microalgae to induce biomass production and high-value metabolite accumulation has been considered as an important factor for sustainable product development.In this study,the efect of plant growth regulators together with basal microalgal cultivation medium on biomass,total lipid,and EPA production was studied using the Plackett–Burman model and Response surface methodology.The traditional one-factor-at-a-time optimization approach is laborious,time-consuming,and requires more experiments which makes the process and analysis more difcult.The Designed PB model was found to be signifcant for biomass(396 mg/L),lipid(254 mg/L),and EPA(5.6%)production with a P value<0.05.The major objective of this study is to formulate a medium for EPA production without compromising the growth properties.Further,we had formulated a new media using RSM to achieve the goal and the signifcant variables selected were NaNO_(3),NaH_(2)PO_(4),and IAA and was found to be signifcant with 16.72%EPA production with a biomass production of 893 mg/L with a P value<0.05.The formulated medium can be used in large-scale cultivation systems which can enhance biomass production as well as the omega 3 fatty acid production in marine microalgae Nannochloropsis oceanica.

关键词： Microalgae Omega 3 fatty acids EPA Plackett–Burman Response surface methodology Plant growth regulators

Implicit Continuous User Authentication for Mobile Devices based on Deep Reinforcement Learning

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Computer Systems Science & Engineering 2023年第2期44卷 1357-1372页

作者： Christy James Jose M.S.Rajasree Government Engineering College Idukki685603India APJ Abdul Kalam Technological University Thiruvananthapuram695016India

The predominant method for smart phone accessing is conﬁned to methods directing the authentication by means of Point-of-Entry that heavily depend on physiological biometrics like,ﬁngerprint or face.Implicit continuous authentication initiating to be loftier to conventional authentication mechanisms by continuously conﬁrming users’identities on continuing basis and mark the instant at which an illegitimate hacker grasps dominance of the session.However,divergent issues remain unaddressed.This research aims to investigate the power of Deep Reinforcement Learning technique to implicit continuous authentication for mobile devices using a method called,Gaussian Weighted Cauchy Kriging-based Continuous Czekanowski’s(GWCK-CC).First,a Gaussian Weighted Non-local Mean Filter Preprocessing model is applied for reducing the noise pre-sent in the raw input face images.Cauchy Kriging Regression function is employed to reduce the dimensionality.Finally,Continuous Czekanowski’s Clas-siﬁcation is utilized for proﬁcient classiﬁcation between the genuine user and attacker.By this way,the proposed GWCK-CC method achieves accurate authen-tication with minimum error rate and time.Experimental assessment of the pro-posed GWCK-CC method and existing methods are carried out with different factors by using UMDAA-02 Face Dataset.The results conﬁrm that the proposed GWCK-CC method enhances authentication accuracy,by 9%,reduces the authen-tication time,and error rate by 44%,and 43%as compared to the existing methods.

关键词： Deep reinforcement learning gaussian weighted non-local meanﬁlter cauchy kriging regression continuous czekanowski’s implicit continuous authentication mobile devices

New Preamble Sequence for WiMAX System with Improved Synchronization Accuracy

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Intelligent Automation & Soft Computing 2023年第3期35卷 3187-3197页

作者： Suma Sekhar Sakuntala S.Pillai S.Santhosh Kumar Department of Electronics and Communication Engineering LBS Institute of Technology for WomenThiruvananthapuramKeralaIndia Mar Baselios College of Engineering and Technology ThiruvananthapuramKeralaIndia Department of Electronics and Communication Govt.Engineering CollegeIdukkiKeralaIndia

Worldwide Interoperability for Microwave Access(WiMAX)trusts Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing(MIMO-OFDM)combination for the deployment of physical layer functions and for connecting the medium access control to the wireless media.Even though Orthogonal Frequency Division Multiplexing(OFDM)facilitates reliable digital broadband transmission in the fading wireless channels,the presence of synchro-nization errors in the form of Carrier Frequency Offset(CFO)and Time Offset(TO)adversely affect the performance of OFDM based physical layers.The objective of this work is to improve the accuracy of the frequency and the time offset estimation in the WiMAX physical layer.A method to enhance the synchro-nization accuracy byﬁne-tuning the merit factor of the preamble sequence is sug-gested in this paper.Also,a new preamble with improved synchronization accuracy is proposed for the WiMAX system.The performance of the proposed preamble is evaluated in a Rayleigh fading channel and the results of simulations show that the Mean Square Error(MSE)in offset estimation is signiﬁcantly reduced and it outperforms the standard WiMAX preamble.

关键词： WiMAX MIMO OFDM time offset carrier frequency offset preamble sequence integrated sidelobe level merit factor