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An analytical solution to wellbore stability using Mogi-Coulomb failure criterion

Journal of Rock Mechanics and Geotechnical Engineering 2019年第6期11卷 1211-1230页

作者： Aditya Singh K.Seshagiri Rao ramanathan ayothiraman Department of Civil Engineering Indian Institute of Technology Delhi

Deep wellbores/boreholes are generally drilled into rocks for oil and gas exploration,monitoring of tectonic stresses *** and tunnel in depth are generally in true triaxial stress state,even if the ground is under axisymmetric loading *** of such wellbores is very critical and collapse of wellbore must be ***-Coulomb failure criterion is a better representation of rock strength under true triaxial *** this paper,an analytical solution is proposed using Mogi-Coulomb failure *** solution is obtained for rock mass exhibiting elastic-perfectly plastic or elastic-brittle-plastic behaviour considering in-plane isotropic *** proposed solution is then compared with exact analytical solution for incompressible material and experimental results of thickwall *** is shown that the results obtained by the proposed analytical solution are in good agreement with the experimental results and exact analytical solution.A reduction of about 13%e20%in plastic zone from the proposed closed-form solution is observed,as compared to the results from the finite element method(FEM)based Mohr-Coulomb ***,the influences of various parameters such as Poisson’s ratio,internal pressure(mud weight),dilation angle,and out-of-plane stress are studied in terms of stress and deformation responses of *** results of the parametric study reveal that variation in the out-of-plane stress has an inverse relation with the radius of plastic ***’s ratio does not have an appreciable influence on the tangential stress,radial stress and radial *** angle has a direct relation with the *** pressure is found to have an inverse relation with the radial deformation and the radius of plastic zone.

关键词： Mogi-coulomb criterion Elastic-brittle-plastic Elastic-perfectly plastic Intermediate principal stress Wellbore stability Tunnel True triaxial strength

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Classification of Rings Associated with the Genus of Clean Graphs

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Algebra Colloquium 2024年第3期31卷 451-466页

作者： V.ramanathan C.Selvaraj Aaqib Altaf S.Pirzada Department of Mathematics Periyar UniversitySalem 636011Tamil NaduIndi Department of Mathematics University of KashmirHazratbalSrinagarKashmirIndia

Let R be a ring(not necessarily commutative)with identity 1 and let CL(R)be its clean *** this paper,we investigate the genus number of the compact Riemann surface in which CL(R)can be embedded and explicitly determine all commutative rings R(up to isomorphism)such that CL(R)has genus at most *** is shown that for any Artinian ring R,CL(R)is a projective graph if and only if R is isomorphic to ***,we determine all isomorphism classes of commutative rings whose clean graphs have crosscap two.

关键词： clean graph commutative ring planar graph genus crosscap

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Post-operative morbidity after neoadjuvant chemotherapy and resection for gallbladder cancer: A national surgical quality improvement program analysis

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World Journal of Gastrointestinal Surgery 2024年第1期16卷 95-102页

作者： Minha Kim Stephanie Stroever Krist Aploks Alexander Ostapenko Xiang Da Dong ramanathan Seshadri Department of General Surgery Danbury HospitalDanburyCT 06810United States Department of Research and Innovation Nuvance HealthDanburyCT 06810United States Division of Surgical Oncology/Hepato-Pancreato-Biliary Surgery Danbury HospitalDanburyCT 06810United States

BACKGROUND Gallbladder cancer is the most common malignancy of the biliary ***-adjuvant chemotherapy(NACT)has improved overall survival by enabling R0 ***,there is no consensus of guidelines for neoadjuvant therapy in gallbladder *** investigations continue to analyze the regimen and benefit of NACT for ongoing care of gallbladder cancer patients,we examined American College of Surgeons National Surgical Quality Improvement Program(NSQIP)database to determine if there was higher morbidity among the neo-adjuvant group within the 30-day post-operative *** hypothesized patients who underwent NACT were more likely to have higher post-operative *** To investigate the 30-day post-operative morbidity outcomes between patients who received NACT and underwent surgery and patients who only had *** A retrospective analysis of the targeted hepatectomy NSQIP data between 2015 and 2019 was performed to determine if NACT in gallbladder cancer increased the risk for post-operative morbidity(bile leak,infection rate,rate of converting to open surgery,etc.)compared to the group who only had *** calculate the odds ratio for the primary and secondary outcomes,a crude logistic regression was *** Of the 452 patients,52 patients received NACT prior to *** were no statistically significant differences in the odds of morbidity between the two groups,including bile leak[odds ratio(OR),0.69;95%confidence interval(95%CI):0.16-2.10;P=0.55],superficial wound infection(OR,0.58;95%CI:0.03-3.02;P=0.61),and organ space wound infection(OR,0.63;95%CI:0.18-1.63;P=0.61).CONCLUSION There was no significant difference in the risk of 30-day post-operative morbidity between the NACT and surgery group and the surgery only group.

关键词： Gallbladder cancer Neoadjuvant chemotherapy Radical cholecystectomy National Surgery Quality Improvement Program Postoperative outcome

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Role of ablation therapy in conjunction with surgical resection for neuroendocrine tumors involving the liver

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World Journal of Gastrointestinal Surgery 2024年第3期16卷 768-776页

作者： Alexander Ostapenko Stephanie Stroever Lud Eyasu Minha Kim Krist Aploks Xiang Da Dong ramanathan Seshadri Department of General Surgery Danbury HospitalDanburyCT 06810United States Department of Research and Innovation Nuvance HealthDanburyCT 06810United States Division of Surgical Oncology/Hepato-Pancreato-Biliary Surgery Danbury HospitalDanburyCT 06810United States

BACKGROUND Resection of hepatic metastasis from neuroendocrine tumors(NETs)improves quality of life and prolongs 5-year *** can be utilized with surgery to achieve complete *** several studies report long-term out-comes for patients undergoing ablation,none have explored perioperative effects of ablation in patients with metastatic *** To determine if intra-operative ablation during hepatectomy increases risk of ad-verse outcomes such as surgical site infections(SSIs),bleeding,and bile *** A retrospective analysis of the hepatectomy National Surgical Quality Impro-vement Program database from 2015-2019 was performed to determine the odds of SSIs,bile leaks,or bleeding in patients undergoing intraoperative ablation when compared to hepatectomy *** Of the 966 patients included in the study,298(30.9%)underwent ablation during *** were 78(11.7%)patients with SSIs in the hepatectomy alone group and 39(13.1%)patients with a SSIs in the hepatectomy with ablation *** leak occurred in 41(6.2%)and 14(4.8%)patients in the two groups,respec-tively;bleeding occurred in 117(17.5%)and 33(11.1%),*** con-trolling for confounding variables,ablation did not increase risk of SSI(P=0.63),bile leak(P=0.34)or bleeding(P=0.07)when compared to patients undergoing resection alone on multivariate *** Intraoperative ablation with hepatic resection for NETs is safe in the perioperative period without significant increased risk of infection,bleeding,or bile *** should utilize this modality when appropriate to a-chieve optimal disease control and outcomes.

关键词： Hepatectomy Neuroendocrine tumor Ablation Bile leaks Bleeding Surgical site infections

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Glacier area change (1993-2019) and its relationship to debris cover, proglacial lakes, and morphological parameters in the Chandra-Bhaga Basin, Western Himalaya, India

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Journal of Mountain Science 2024年第4期21卷 1287-1306页

作者： VATSAL Sarvagya AZAM Mohd Farooq BHARDWAJ Anshuman MANDAL Arindan BAHUGUNA Ishmohan ramanathan Alagappan RAJU N.Janardhana TOMAR Sangita Singh Department of Civil Engineering Indian Institute of Technology IndoreSimrol 453552India School of Geosciences University of AberdeenKing’s CollegeAberdeen AB243FXUnited Kingdom Interdisciplinary Centre for Water Research Indian Institute of ScienceBengaluru 560012India Space Application Centre Ahmedabad 380015India School of Environmental Sciences Jawaharlal Nehru UniversityNew Delhi 110067India Department of Geography Norwegian University of Science and TechnologyTrondheim No-7491Norway

Glacier inventories serve as critical baseline data for understanding the impacts of climate change on *** present study maps the outlines of glaciers in the Chandra-Bhaga Basin(western Himalaya)for the years 1993,2000,2010,and 2019 using Landsat Thematic Mapper(TM),Enhanced Thematic Mapper(ETM),and Operational Land Imager(OLI)datasets.A total of 251 glaciers,each having an area above 0.5 km^(2),were identified,which include 216 clean-ice and 35 debris-covered *** changes are estimated for three periods:1993-2000,2000-2010,and *** total glacierized area was 996±62 km^(2) in 1993,which decreased to 973±70 km^(2) in *** mean rate of glacier area loss was higher in the recent decade(2010-2019),at 0.036 km^(2),compared to previous decades(0.029 km^(2) in 2000-2010 and 0.025 km^(2) in 1993-2000).Supraglacial debris cover changes are also mapped over the period of 1993 and *** is found that the supraglacial debris cover increased by 14.12±2.54 km^(2)(15.2%)during *** field surveys on Chhota Shigri,Panchi II,Patsio,Hamtah,Mulkila,and Yoche Lungpa glaciers were carried out to validate the glacier outlines and supraglacial debris cover estimated using satellite *** of various morphological parameters on retreat were also *** is observed that small,clean ice,south oriented glaciers,and glaciers with proglacial lakes are losing area at faster rates than other glaciers in the basin.

关键词： Glacier Area change Debris cover Morphology Proglacial lake

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Electrochemical capacitance of nanostructured ruthenium- doped tin oxide Sn1-xRuxO2 by the microemulsion method

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Frontiers of Materials Science 2017年第4期11卷 385-394页

作者： ramanathan SARASWATHY Department of Physics Velammal Institute of Technology Panchetti Thiruvallur-601204 India

Synthesis of nanostructured Ru-doped SnO2 was successfully carried out using the reverse microemulsion method. The phase purity and the crystallite size were analyzed by XRD. The surface morphology and the microstructure of synthesized nanoparticles were analyzed by SEM and TEM. The vibration mode of nanoparticles was investigated using FTIR and Raman studies. The electrochemical behavior of the Ru- doped SnO2 electrode was evaluated in a 0.1 mol/L Na2SO4 solution using cyclic voltammetry. The 5% Ru-doped SnO2 electrode exhibited a high specific capacitance of 535.6 Fig at a scan rate 20 mV/s, possessing good conductivity as well as the electro- cycling stability. The Ru-doped SnO2 composite shows excellent electrochemical properties, suggesting that this composite is a promising material for supercapacitors.

关键词： reverse microemulsion tin oxide nanomaterials supercapacitor electrochemical property

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An Efficient SDFRM Security System for Blockchain Based Internet of Things

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Intelligent Automation & Soft Computing 2023年第2期35卷 1545-1563页

作者： Vivekraj Mannayee Thirumalai ramanathan Faculty of Mechanical Engineering Anna UniversityChennai600025Tamil NaduIndia Department of Mechanical Engineering Dr.N.G.P.Institute of Technology641048Tamil NaduIndia

Blockchain has recently sparked interest in both the technological and businessﬁ*** Internet of Things's(IoT)core principle emerged due to the connectivity of several new technologies,including wireless technology,the Inter-net,embedded automation systems,and micro-electromechanical ***-facturing environments and operations have been successfully converted by implementing recent advanced technology like Cloud Computing(CC),Cyber-Physical System(CSP),Information and Communication Technologies(ICT)and Enterprise Model,and other technological innovations into the fourth indus-trial revolution referred to as Industry *** management is deﬁned as the pro-cess of accumulation in order to make better business decisions,and process,secure and store information about a *** the incipient model,there are interconnected contrivances and Machine-to-Machine(M2M)interactions,and transaction data are stored on the *** is a challenging aspect that must be punctiliously considered during the design and development phases of a *** this research article,we proposed a Secure and Distributed Framework for Resource Management(SDFRM)in Industry 4.0 environments within a distribu-ted and collaborative Industry 4.0 system,the dynamic and trust-based Distributed Management Framework(DMF)of shared resource *** issues are focused by taking into account of the traditional characteristics of IoT/Industrial Internet of Things’(IIoT)-predicated environments,an SDFRM in Industry 4.0 environments within a distributed and collaborative Industry 4.0 ***,to ensure strong privacy over the procedures associated with Access Control(AC),a privacy-preserving method is proposed and integrated into the *** proposed DMF,based on blockchain technology and peer-to-peer networks,allows dynamic access management and system governance without using third parties who could be *** worked hard to design and implement the pro-posal to demonstrate its

关键词： Internet of things blockchain data privacy security system distributed management IIoT

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Suspended sediment dynamics in the meltwater of Chhota Shigri glacier, Chandra basin, Lahaul-Spiti valley, India

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Journal of Mountain Science 2018年第1期15卷 68-81页

作者： Virendra Bahadur SINGH AL.ramanathan School of Environmental Sciences Jawaharlal Nehru University

Present study shows suspended sediment dynamics in the meltwater of Chhota Shigri glacier,Himachal Pradesh,India for different melt seasons during the period *** suspended sediment concentration in the meltwater was found during the month of July 2011,2012 and 2014 constituting to 55.2%,48.3% and 46.9%,*** in 2013,maximum suspended sediment concentration was observed in August accounting for46.1% of the *** the other hand,maximum suspended sediment load was monitored in the month of July 2011,2012 and 2014 constituting 59.5%,63% and 55.7% of the total,*** in2013,maximum suspended sediment load was observed in the month of August accounting for 49.8% of the total suspended sediment *** distribution of suspended sediment concentration(SSC)and suspended sediment load(SSL)in the Chhota Shigri glacier shows higher value of SSC and SSL during the study period 2012 and 2013,which may be due to the presence of high glacial runoff and negative mass balance of the studied area during these time *** diurnal variation has been observed in the SSC of *** correlation was observed between SSC and SSL with *** the other hand,SSC and SSL also showed strong exponential correlation with air temperature of the studied *** yield from the catchment of Chhota Shigri glacier is high during the peak melt season(July and August)and low during the late melt season(September and October).The average value of erosion rate for Chhota Shigri glacier basin during the study period 2011-2014 was calculated to be 1.1mm/yr,which is lower than the average erosion rate of other Himalayan glaciers such as Rakiot,Chorabari and Gangotri glaciers,which may be caused by its geological setting containing high erosion resistant rocks such as granite,granite gneiss and porphyritic granite.

关键词： Suspended sediment concentration Hysteresis Sediment yield Erosion rate Western Himalaya Chhota Shigri glacier

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DIAGNOSIS OF WAVE ACTIVITY OVER RAINBAND OF LANDFALL TYPHOON

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Journal of Tropical Meteorology 2009年第2期15卷 121-129页

作者：冉令坤 Abdul REHIM AL ramanathan Institute of Atmospheric Physics Chinese Academy of Sciences Bangladesh Meteorological Department School of Environmental Science Jawaharlal Nehru University

A generalized wave-activity density, which is defined as an absolute value of production of three-dimensional vorticity vector perturbation and gradient of general potential temperature perturbation, is introduced and its wave-activity law is derived in Cartesian coordinates. Constructed in an agoestrophic and nonhydrostatie dynamical framework, the generalized wave-activity law may be applicable to diagnose mesoscale weather systems leading to heavy rainfall. The generalized wave-activity density and wave-activity flux divergence were calculated with the objective analysis data to investigate the character of wave activity over heavy-rainfall regions. The primary dynamical processes responsible for disturbance associated with heavy rainfall were also analyzed. It was shown that the generalized wave-activity density was closely correlated to the observed 6-h accumulative rainfall. This indicated that the wave activity or disturbance was evident over the frontal and landfall-typhoon heavy-rainfall regions in middle and lower troposphere. For the landfall-typhoon rainband, the portion of generalized wave-activity flux divergence, denoting the interaction between the basic-state cyclonic circulation of landfall typhoon and mesoscale waves, was the primary dynamic process responsible for the evolution of generalized wave-activity density.

关键词： dynamic meteorology wave-activity density wave-activity flux divergence landfall typhoon, heavy-rainfall event

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Humic substances:Structure,function and benefits for agroecosystems—a review

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Pedosphere 2023年第2期33卷 237-249页

作者： Jaya TIWARI AL ramanathan Kuldeep BAUDDH John KORSTAD Department of Community Medicine and School of Public Health Postgraduate Institute of Medical Education and ResearchChandigarh 160012(India) Skill faculty of Applied Sciences and Humanities Shri Vishwakarma Skill UniversityPalwal Haryana 121102(India) School of Environmental Sciences Jawaharlal Nehru UniversityNew Delhi 110067(India) Department of Environmental Sciences Central University of JharkhandRanchi 835205(India) Department of Biology and Global Environmental Sustainability Oral Roberts UniversityTulsa OK 74171(USA)

The increasing global demand for food production,often causing excessive use of chemical fertilizers,has led to the deterioration of soil *** action is required to restore soil health in a sustainable *** review advocates switching to use of organic matter(manure and compost)that contains vital nutrients for plant growth and helps restore soil *** substances(HSs),derived from degraded plant remains and found ubiquitously in nature,are an important source of organic *** application of HSs to soil enhances essential nutrient supply and assimilation of atmospheric CO_(2)due to increasing biomass *** HS application globally can help lower atmospheric CO_(2)concentrations and create a sustainable agricultural ***,the process of humification and the molecular structure of HSs remain poorly understood subjects in soil ***,it is imperative to understand the mechanisms underlying various roles of HSs in *** review offers an insight into the various structural and functional aspects of HSs,particularly fulvic acid and humic *** dynamic and interactive nature of HSs creates a framework for sustainable agriculture.

关键词： fulvic acid humic acid humin humus nutrient supply soil health sustainable agriculture

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