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CFD modeling to study the effect of particle size on dispersion in 20l explosion chamber: An overview

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International Journal of Mining Science and Technology 2020年第3期30卷 321-327页

作者： santosh kumar Ray Niroj kumar Mohalik Asfar Mobin Khan Debashish Mishra Nikhil kumar Varma Jai Krishna Pandey Pradeep kumar Singh CSIR-Central Institute of Mining and Fuel Research Dhanbad 826001India

Mine disasters occur predominantly due to methane or coal dust explosion or a combination of *** the top ten worst coal mine disasters in India, nine are due to coal dust explosion. The current paper describes a general overview of the parameters causing dispersion leading to coal dust explosion,and computational fluid dynamics(CFD) simulation study to observe the effects of particle size on dispersion in Indian coal mines. Turbulent kinetic energy(TKE) and velocity vector path of dust-air mixture and dust-free air were simulated to understand their effects on coal dust dispersion. The TKE contours and velocity vector paths for dust-free air were uniform and symmetrical due to resistance-free path available. The TKE contours and velocity vector paths for dust-air mixture shows the asymmetrical distribution of contours, due to entrainment of air with dust particles. Vortices were observed in velocity vector paths which gradually diminish on increment of time sequence. These vortices are dead centres where velocity and coal dust particles concentration are both zero.

关键词： Coal dust explosibility CFD 20l explosion chamber Dispersion Turbulent kinetic energy

A detailed study on trust management techniques for security and privacy in IoT:challenges,trends,and research directions

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高置信计算(英文) 2023年第2期3卷 71-82页

作者： Himani Tyagi Rajendra kumar santosh Kr Pandey Department of Computer Science Jamia Millia IslamiaNew Delhi 110025India Department of EC&IT MeityNew Delhi 110003India

The Internet of Things is a modern technology that is directed at easing human life by automating most of the things used in daily *** never-ending dependency on the network for communication is attracting adversaries to exploit the vulnerabilities of ***,this technology is facing some serious issues and challenges concerning security and *** issues and challenges are the real motivation behind considering this ***,this survey includes a discussion about security and privacy challenges as well as available solutions for IoT based wireless sensor *** systematic literature review(SLR)focuses particularly on a popular and applicable security approach known as Trust Management System(TMS).Firstly,all aspects of trust management,including trust indicators,trust properties,trust evaluation,trust building,trust models and the importance of those models for security and privacy,trust prediction methodologies,and ultimately trust-based attacks,are covered in this ***,trust management schemes are classified into four groups based on the methodology used for trust-based security solutions in the IoT:cryptography-based,computational and probabilistic-based,information theory-based,and ***,an understanding of the problems and difficulties with current methodologies is given,along with suggestions for further ***,the SLR is concluded by formulating the desirable characteristics of a trust management system in the IoT and proposing a trust model suitable for IoT networks.

关键词： Trust Trust management approaches IoT Security Privacy Reliability Attacks Trust attributes Systematic literature review Cybersecurity

TGA/DSC study to characterise and classify coal seams conforming to susceptibility towards spontaneous combustion

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International Journal of Mining Science and Technology 2022年第1期32卷 75-88页

作者： Niroj kumar Mohalik Somu Mandal santosh kumar Ray Asfar Mobin Khan Debashish Mishra Jai Krishna Pandey CSIR-Central Institute of Mining and Fuel Research(CIMFR) Dhanbad 826015India Academy of Scientific and Innovative Research(AcSIR) Ghaziabad 201002India

Thermogravimetric analysis/differential scanning calorimeter(TGA/DSC)technique along with basic coal characteristics study is carried out for eighty coal samples of Indian coalfields,to determine spontaneous combustion propensity behaviour of *** study of coal samples indicates that there is an increase in the mass of coal samples in the temperature range 150-350℃,which may be due to oxygen adsorption and *** correlation and principal component analysis states that the component of proximate analysis(M_(ad),VM_(d),FR,and VR)have an acceptable correlation with the TGA experiments results i.e.,Tgsh and *** fixed nonlinear regression analysis shows that thermogravimetry(TG)experiment results Tgign may be the best index to categorise/classify the coal as per their susceptibility towards spontaneous *** authors proposed four groups of classification as per their propensity towards spontaneous combustion depending upon the moisture(M_(ad)),volatile matter(VM_(d)),and TG ignition temperature from differential thermogravimetric(DTG)curve(Tgign)using hierarchal clustering *** coal samples of different seams from Indian coalfield may be classified into four different clusters,*** highly/extremely susceptible(Tgign320℃).The field observations and TGA/DSC experiment results with the following statistical analysis substantiate a similar assessment.

关键词： Coal TGA/DSC Spontaneous combustion TG ignition

Impact of COVID-19 Pandemic on Mental Health of Healthcare Workers–A Perception of Indian Hospital Administrators

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International Journal of Mental Health Promotion 2023年第7期25卷 833-845页

作者： Anahita Ali santosh kumar Faculty of Public Health Poornima UniversityJaipur303905India

Since the coronavirus pandemic,many factors led to the change in the mental well-being of hospital administrators and their *** pandemic negatively impacted the availability and capability of health professionals to deliver essential services and meet rising ***,this study aimed to understand the perspective of hospital administrators about issues and challenges that negatively impacted their staff’s mental health and hospital administrators’coping response to mitigate those challenges and *** exploratory qualitative study was conducted with 17 hospital administrators(superintendents,deputy superintendents,nursing in charge and hospital in charge)working in a government district hospital of Rajasthan state during September 2022 and October *** study revealed various emerging themes on mental health-related issues,challenges and coping strategies reported by the *** and sub-themes that emerged from this study were 1)Perceived mental health of HCWs-perceived importance of mental health,2)Impact of COVID-19 on the mental health of HCWs–common mental health issues,changes in mental health pre and post-pandemic,3)Impact of COVID-19 on health behavior of HCWs-increased self-care and awareness,4)Challenges responsible for poor mental health of HCWs-organizational,ethical and societal challenges and 5)Strategies to retain mental health of HCWs-effective coping *** most common problems were increased levels of stress,feeling fatigued,tiredness,weak and anxiety among the *** their staff motivated was the biggest challenge *** support,counseling through professionals and demystifying myths were the most effective coping strategies adopted by the *** conclusion,this study reported poor mental health-related issues,challenges faced by the HCWs and effective strategies adopted by hospital administrators during tough *** study will assist hospital administrators in developing i

关键词： Coping strategies Indian administrators Indian healthcare workers qualitative study COVID-19 mental health

Determining bioclimatic space of Himalayan alder for agroforestry systems in Nepal

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Plant Diversity 2018年第1期40卷 1-18页

作者： santosh kumar Rana Hum Kala Rana Krishna kumar Shrestha Suresh Sujakhu Sailesh Ranjitkar Key Laboratory{or Plant Diversity and Biogeography of East Asia Kunming Institute of BotanyKunming 650201China University of Chinese Academy of Sciences Beijing 100049China Systematics and Biodiversity Unit Central Department of BotanyTribhuvan UniversityKirtipurKathmanduNepal jade Consult Private Limited KabilmargThapathaliKathmanduPOB 746Nepal World Agroforestry Centre East and Central Asia 132 Lanhei RdHeilongtanKunmingChina

Himalayan alder species are proven to be very useful in traditional as well as contemporary agroforestry practice. These nitrogen-fixing trees are also useful in the land restoration. Therefore, understanding the distribution of Himalayan alder and the potential zone for plantation is meaningful in the agroforestry sector. Suitable climatic zones of Alnus spp. were modelled in Max Ent software using a subset of least correlated bioclimatic variables for current conditions(1950 -2000), topographic variables(DEM derived) and Landuse Landcover(LULC) data. We generated several models and selected the best model against random models using ANOVA and t-test. The environmental variables that best explained the current distribution of the species were identified and used to project into the future. For future projections, ensemble scenarios of climate change projection derived from the results of 19 Earth System Models(ESM) were used. Our model revealed that the most favorable conditions for Alnus nepalensis are in central Nepal in the moist north-west facing slope, whereas for Alnus nitida they are in western *** major climatic factor that contributes to Alnus species distribution in Nepal appears to be precipitation during the warmest quarter for A. nepalensis and precipitation during the driest quarter for A. nitida. Future projections revealed changes in the probability distribution of these species, as well as where they need conservation and where they can be planted. Also, our model predicts that the distribution of Alnus spp. in hilly regions will remain unchanged, and therefore may represent sites that can be used to revitalize traditional agroforestry systems and extract source material for land restoration.

关键词： Alder Agroforestry Species distribution modeling Climate change MaxEnt

Bandgap engineered novel g-C_3N_4/G/h-BN heterostructure for electronic applications

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Journal of Semiconductors 2019年第3期40卷 45-49页

作者： santosh kumar Gupta Rupesh Shukla Department of Electronics & Communication Engineering Motilal Nehru National Institute of Technology Allahabad Department of Electrical & Electronics Engineering Loknayak Jai Prakash Institute of Technology Chhapra

The effect of an external electric field on the bandgap is observed for two proposed heterostructures graphitic carbon nitride-graphene-hexagonal boron nitride(g-C_3N_4/G/h-BN) in hexagonal stack(AAA) and graphene-graphitic carbon nitridehexagonal boron nitride(G/g-C_3N_4/h-BN) in Bernal stack(ABA). Their inter-layer distance, binding energy and effective mass has also been calculated. The structure optimization has been done by density functional theory(DFT) with van der Waals corrections. The inter-layer distance, bandgap, binding energy and effective mass has been listed for these heterostructures and compared with that of bilayer graphene(BLG), graphene-hexagonal boron nitride(G/h-BN) hetero-bilayer, graphene-graphitic carbon nitride(G/g-C_3N_4) hetero-bilayer and graphitic carbon nitride-graphene-graphitic carbon nitride(g-C_3N_4/G/g-C_3N_4) heterostructure in Bernal and hexagonal stack. g-C_3N_4/G/h-BN is found to offer lower effective mass and larger bandgap opening among the considered heterostructures.

关键词： bandgap graphene h-BN g-C3N4 binding energy DFT

YFa and analogs:Investigation of opioid receptors in smooth muscle contraction

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World Journal of Gastroenterology 2011年第40期17卷 4523-4531页

作者： Krishan kumar Ritika Goyal Annu Mudgal Anita Mohan santosh Pasha Peptide Synthesis Laboratory Institute of Genomics and Integrative Biology Delhi 110007 India University School of Basic and Applied Sciences GGSIP University Sector-16 C Dwarka Delhi 110075 India Department of Chemistry Motilal Nehru College University of Delhi Delhi 110021 India

AIM:To study the pharmacological profile and inhibition of smooth muscle contraction by YFa and its analogs in conjunction with their receptor selectivity. METHODS:The effects of YFa and its analogs (D-Ala2) YFa, Y (D-Ala2) GFMKKKFMRF amide and Des-Phe-YGGFMKKKFMR amide in guinea pig ileum (GPI) and mouse vas deferens (MVD) motility were studied using an isolated tissue organ bath system, and morphine and DynA (1-13) served as controls. Acetylcholine was used for muscle stimulation. The observations were validated by specific antagonist pretreatment experiments using naloxonazine, naltrindole and norbinaltor-phimine norBNI. RESULTS:YFa did not demonstrate significant inhibition of GPI muscle contraction as compared with mor-phine (15% vs 62%, P = 0.0002), but moderate inhibition of MVD muscle contraction, indicating the role of κ opioid receptors in the contraction. A moderate inhibition of GPI muscles by (Des-Phe) YFa revealed the role of anti-opiate receptors in the smooth muscle contraction. (D-Ala-2) YFa showed significant inhibition of smooth muscle contraction, indicating the involvement of mainly δ receptors in MVD contraction. These results were supported by specific antagonist pretreatment assays. CONCLUSION:YFa revealed its side-effect-free analgesic properties with regard to arrest of gastroin-testinal transit. The study provides evidences for the involvement of κ and anti-opioid receptors in smooth muscle contraction.

关键词： Opioid receptor Guinea pig ileum Mousevas deferens Smooth muscle contraction Gastrointestinal motility

Strength and dilatancy behaviors of deep sands in Shanghai with a focus on grain size and shape effect

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第6期12卷 1214-1225页

作者： Bandana Tiwaria Guanlin Ye Mingguang Li Usama Khalid santosh kumar Yadav Department of Civil Engineering and State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai200240China Department of Civil Engineering IOEPulchowk CampusTribhuvan UniversityLalitpur44700Nepal

With rapid development of infrastructures like tunnels and open excavations in Shanghai,investigations on deeper soils have become critically *** of the existing laboratory works were focused on the clayey strata up to Layer 6 in Shanghai,*** depth of up to 40 *** this paper,Layers 7,9,and 11,which were mostly formed of sandy soils at depth of up to 150 m,were experimentally investigated with respect to physico-mechanical *** stressestrain behaviors were analyzed by the consolidated drained/undrained(CD/CU)triaxial tests under monotonic ***-dimensional(1D)oedometer tests were performed to investigate the consolidation properties of the sandy *** were prepared at three different relative densities for each ***,the micro-images and particle size analyzers were used to analyze the shape and size of the sand *** influences of grain size,density,and angularity on the stressestrain behaviors and compressibility were also *** to the other layers,Layer 11 had the smallest mean grain size(D50),highest compressibility,and lowest shear *** contrast,Layer 9 had the largest mean grain size,lowest compressibility,and highest shear *** 7 was of intermediate mean grain size,exhibiting more compressibility and less shear strength than that of Layer ***,the critical state parameters and maximum dilatancy rate of different layers were discussed.

关键词： Deep sands in Shanghai Laboratory tests Shear strength Dilatancy Relative density

Structural Tuning of Low Band Gap Intermolecular Push/Pull Side-chain Polymers for Organic Photovoltaic Applications

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Chinese Journal of Polymer Science 2017年第9期35卷 1073-1085页

作者： Ansuman Nayak P.S. Rama Sreekanth santosh kumar Sahu Duryodhan Sahu Department of Chemistry National Institute of Science and Technology Palur Hills Berhampur Odisha India 761008 Department of Chemistry Gandhi Institute of Engineering and Technology Gunpur Odisha India Department of Mechanical Engineering National Institute of Science and Technology Palur Hills Berhampur Odisha India 761008

A series of novel low band gap donor-acceptor （D-A） type organic co-polymers （BT-F-TPA, BT-CZ-TPA and BT-SI-TPA） consisting of electron-deficient acceptor blocks both in main chains （M1） and at the pendant （M2） were polymerized with different electron rich donor （M3-M5） blocks, i.e., 9,9-dihexyl-9H-fluorene, N-alkyl-2,7-carbazole, and 2,6-dithinosilole, respectively, via Suzuki method. These polymers exhibited relatively low band gaps （1.65-1.88 eV） and broad absorption ranges （680-740 nm）. Bulk heterojunction （BHJ） solar cells incorporating these polymers as electron donors, blended with [6,6]-phenyl-C61-butyric acid methyl ester （PC61BM） or [6,6]-phenyl-Cvl-butyric acid methyl ester （PC71BM） as electron-acceptors in different weight ratios were fabricated and tested under 100 mW/cm2 of AM 1.5 with white-light illumination. The photovoltaic device containing donor BT-SI-TPA and acceptor PC71BM in 1：2 weight ratio showed the best power conversion efficiency （PCE） value of 1.88%, with open circuit voltage （Voc） = 0.75 V, short circuit current density （Jsc） = 7.60 mA/cm2, and fill factor （FF） = 33.0%.

关键词： Polymer solar cells Low band gap Conducting polymers Charge transfer Donor-acceptor Bulk heterojunctionsolar cell