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Bianchi type-I cosmological models with perfect fluid in general relativity

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Research in Astronomy and Astrophysics 2010年第4期10卷 291-300页

作者： Rishi kumar tiwari Department of Mathematics Govt.Model Science College

Einstein＇s field equations with variable gravitational and cosmological constants are considered in the presence of perfect fluid for the Bianchi type-I universe by assuming that the cosmological term is proportional to R-m （R is a scale factor and m is a constant）.A variety of solutions are *** physical significance of the respective cosmological models are also discussed.

关键词： cosmological parameters - cosmology: theory - relativity

In vivo immunostimulatory effect of the amoebocyte lysate and plasma of Asian horseshoe crab,Tachypleus gigas in a piscine model

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Marine Life Science & Technology 2021年第3期3卷 355-362页

作者： Sukanta kumar Nayak pramod kumar Nanda Priyabrat Swain Department of Biotechnology Maharaja Sriram Chandra Bhanja Deo University(Erstwhile North Orissa University)Odisha757003India ICAR-Indian Veterinary Research Institute Eastern Regional StationKolkata700037India Fish Health Management Division Central Institute of Freshwater AquacultureBhubaneswar751002India

Antimicrobial proteins/peptides are becoming a new generation of immunostimulants for prevention and disease control in human and animals,including aquatic *** the haemolymph of horseshoe crabs(Tachypleus)contains broad ranges of bioactive compounds,we have explored the in vivo immunostimulating potential of amoebocyte lysate and plasma using a fish *** major carp,Labeo rohita,yearlings were injected intraperitoneally with two doses of lysate and plasma at 50 and 100µg protein per *** abnormalities and/or mortalities were recorded in any *** injected with 50µg lysate and 100µg plasma protein showed significant enhancement(P0.01)in any *** the contrary,a significantly high hemolysin titre was recorded in fish that received 100µg plasma *** challenge with Aeromonas hydrophila,both lysate and plasma protein(s)cross protected the fish after 30 *** highest survival(50%)was recorded in group injected with 50µg lysate protein,followed by 45%in both 100µg lysate and plasma protein injected groups.

关键词： Amoebocyte lysate Immunostimulatory Labeo rohita Plasma Tachypleus gigas

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Journal of Ocean Engineering and Science 2023年第2期8卷 111-123页

作者： Raj kumar Ravi Shankar Verma Atul kumar tiwari Department of Mathematics Faculty of Engineering&TechnologyVeer Bahadur Singh Purvanchal UniversityJaunpur222003India Department of Mathematics Motihari College of EngineeringMotihari845401BiharIndia

This work is devoted to get a new family of analytical solutions of the(2+1)-coupled dispersive long wave equations propagating in an infinitely long channel with constant depth,and can be observed in an open sea or in wide *** solutions are obtained by using the invariance property of the similarity transformations method via one-parameter Lie group *** repeated use of the similarity transformations method can transform the system of PDEs into system of *** adequate restrictions,the reduced system of ODEs is *** simulation is performed to describe the solutions in a physically meaningful *** profiles of the solutions are simulated by taking an appropriate choice of functions and constants involved *** each animation,a frame for dominated behavior is *** exhibit elastic multisolitons,single soliton,doubly solitons,stationary,kink and parabolic *** results are significant since these have confirmed some of the established results of *** et al.(2020)and *** et al.(2020).Some of their solutions can be deduced from the results derived in this *** results in the existing literature are different from those in this work.

关键词： Dispersive long wave equations Solitons Invariants Lie-group Similarity solutions

Estimation of the internal and external damping from the forward and backward spectrum of a rotor with a fatigue crack

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Propulsion and Power Research 2020年第1期9卷 62-74页

作者： Dipendra kumar Roy Rajiv tiwari Department of Mechanical Engineering Indian Institute of Technology GuwahatiAssam781039India Faculty of Mechanical Engineering Indian Institute of Technology GuwahatiAssam781039India

Both internal and external damping are concurrently present in a rotor ***,the internal damping that originates from various sources often leads to instability in the rotor system,and hence its accurate estimation is *** goal of the present paper is to distinctly estimate both external and internal damping in a Jeffcott rotor containing transverse *** modelling of the fatigue crack is based on the assumption of a switching crack,which additionally provides the internal damping due to rubbing on crack faces,which is hardly addressed in ***,the fatigue crack leads to the forward and backward whirls due to asymmetry in the *** the process of development of the identification procedure in the form of the regression equation for the estimation of internal damping,other important unknown rotor system parameters,like the external damping,unbalance and loss of stiffness of the shaft due to the crack,are also *** reduces the estimation error of the internal damping due to reduction in deviations of other model *** simulated responses are obtained from equations of motion of the rotor system in the form of a closed-form expression and by the Runge-Kutta integration *** full-spectrum response data(both magnitude and phase)are utilized during the testing of the proposed identification *** corrections have been incorporated in the *** noise is added in numerical responses during identification of parameters to check the robustness of the algorithm and found to be working satisfactorily.

关键词： Internal damping External damping Switching crack Unbalance Full spectrum

Climate change and finger millet: Perception, trend and impact on yield in different ecological regions in Central Nepal

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Journal of Mountain Science 2019年第4期16卷 821-835页

作者： Dol Raj LUITEL Mohan SIWAKOTI pramod kumar JHA Central Department of Botany Tribhuvan University Department of Environment Ministry of Forests and Environment

The views of local people on climate change along different ecological regions are relatively unexplored in Nepal. This study was conducted in 13 villages in central Nepal at different altitudes to document the views of small holder farmers and compare their perception with trends of climatic variables, finger millet yield, natural disasters, plant phenology(flowering and fruiting), status of forest and wild life, as well as the spread of diseases and pests. Analysis on the climatic data of stations for 36-41 years between 1975 and 2016 showed significant increases in the minimum temperature in lower tropical climatic region(<500 m), upper tropical to subtropical climatic region(500-2000 m) and temperate climatic region(2000-3000 m) by 0.01, 0.026 and 0.054℃/year, respectively, and an increase of maximum temperature by 0.008, 0.018, and 0.019℃/year, respectively. Rainfall showed a strongly significant decreasing trend in all elevation regions. This result matches with the views of respondents except 38% respondent from temperate climatic region. People from the temperate climatic region also mentioned that current onset of snowfall is delayed but amount of snowfall remained the same. From the documented records, except events of wild fire, frequency of natural disasters events have increased in the recent years, which was in harmony with the views of local people. Multi-linear regression analysis showed that contribution of climatic variables on finger millet yield in lower tropical climatic region and upper tropical to subtropical regions was 23% and 57.3%, respectively, which was supported by increasing trend on average growing degree day(GDD) temperature at the rate of 0.01℃ in upper tropical to subtropical region and 0.007℃ in lower tropical climatic region yearly. Finger millet yield has been increasing at the rate of 7.39 and 36.9 kg/ha yearly in lower tropical climatic region and upper tropical to subtropical climatic region, respectively. This result provide

关键词： Climate change Growing degree days (GDD) Natural disaster Phenology Precipitation Small holder farmers

Synthesis,isolation,identification and characterization of new process-related impurity in isoproterenol hydrochloride by HPLC,LC/ESI-MS and NMR

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Journal of Pharmaceutical Analysis 2017年第6期7卷 394-400页

作者： Neeraj kumar Subba Rao Devineni Prasad Reddy Gajjala Shailendra kumar Dubey pramod kumar Chemical Research Department Micro Labs LtdAPI DivisionBommasandra-Jigani Link RoadKIADB INDL AreaBommasandraBangalore 560105KarnatakaIndia

One unknown impurity （Imp-II） during the analysis of laboratory batches of isoproterenol hydrochloride was detected in the level ranging from 0.04% to 0.12% by high performance liquid chromatography with UV detection. The unknown impurity structure was proposed as 4-[2-（propan-2oylamino）ethyl]benzene-l,2-diol （Imp-II） using the liquid chromatography-mass spectrophotometry （LC-MS） analysis. Imp-II was isolated by semi-preparative liquid chromatography from the impurity-enriched reaction crude sample. Its proposed structure was confirmed by nuclear magnetic spectroscopy such as 1H, 13C, DEPT （1D NMR）, HSQC （2D NMR） and infrared spectroscopy （IR）, and retention time and purity with HPLC followed by the chemical synthesis. Due to less removable nature of Imp-II during the purification, the synthetic process was optimized proficiently to control the formation of Imp-II below to the limit 〈 0.12% in the course of reaction. The new chemical route was developed for the preparation of this impurity in required quantity with purity to use as reference standard. The most probable mechanism for the formation of Imp-II was discussed in details.

关键词： Isoproterenol hydrochloride Impurities HPLC NMR

Plant endemism in the Nepal Himalayas and phytogeographical implications

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Plant Diversity 2019年第3期41卷 174-182页

作者： Achyut tiwari Yadav Uprety Santosh kumar Rana Department of Botany Tri-Chandra Campus Tribhuvan University Kathmandu Nepal Central Department of Botany Tribhuvan University Kirtipur Kathmandu Nepal Research Centre for Applied Science and Technology Tribhuvan University Kathmandu Nepal IUCN (International Union for Conservation of Nature) Kathmandu Nepal Key Laboratory for Plant Diversity and Biogeography of East Asia Kunming Institute of Botany Chinese Academy of Sciences Kunming 650201 Yunnan China University of Chinese Academy of Sciences Beijing 100049 China

Nepal is located in the central part of the greater Himalayan range with a unique series of mountain chains formed by recent mountain building geological events. As one of the youngest mountains in the world it contributes to diversity of plants and also provided barriers to and corridors through which plants migrated during the ice ages. The higher altitudinal variation with the high mountains, deep river valleys and lowland plains combine with the effects of the summer monsoon and dry winter result with an extraordinary diversity of ecosystems including flora and fauna in a relatively small land area. The existing checklists for Nepal record some 6000 species of flowering plants and about 530 ferns. However, the botanical experts estimate that numbers may go up to 7000 when the poorly known remote regions are fully explored. The information on plant endemism in Nepal Himalaya is not adequately known as Nepal is still struggling to complete long awaited Flora of Nepal project. Endemic species are confined to specific areas and are the first to be affected by land use and other global changes. We sought to explore the spatial distribution of endemic plant species in Nepal in relation to the consequences associated with climatic and geologic changes over time in the region with the help of published literature. It was found that the endemism showed marked spatial variation between open moist habitat and dry inner valleys, the former with higher endemism. The updated records showed 312 flowering plant species to be endemic to Nepal with higher endemism around the elevation of 3800e4200 m at sea level. The recent human population explosion, intensified deforestation, habitat fragmentation and modern day environmental changes are posing greater threats to endemic plant in Nepal. The conservation status and threats to these peculiar species are unknown. Nevertheless, environmental degradation and high poverty rates create a potent mix of threats to biodiversity in this l

关键词： Himalaya Topography Endemism

Exploring the potential of artificial intelligence techniques in prediction of the removal efficiency of vortex tube silt ejector

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International Journal of Sediment Research 2023年第4期38卷 615-627页

作者： Sanjeev kumar Chandra Shekhar Prasad Ojha Nand kumar tiwari Subodh Ranjan Department of Civil Engineering Indian Institute of Technology Department of Civil Engineering National Institute of Technology

A vortex tube silt ejector is a curative hydraulic structure used to remove sediment deposits from canals and is recognized as one of the most efficient substitutes for physically removing canal sediment. The spatially varied flow in the channel and the rotational flow behavior in the tube make the silt removal process complex. It is even harder to accurately predict the silt removal efficiency by traditional models accurately. However, artificial intelligence(AI) and machine learning approaches have emerged as robust substitutes for studying complex processes. Therefore, this research makes use of AI approaches; support vector machine(SVM), random forest(RF), random tree(RT), and multivariate adaptive regression spline(MARS) to compute the vortex tube silt ejection efficiency using the laboratory data sets. The outcomes of the artificial intelligence(AI)-based techniques also were compared with traditional models. It was found that the RT model(root mean square error, RMSE = 2.165, Nash Sutcliffe efficiency, NSE = 0.98) outperforms the other applied approaches which had relatively more significant result errors. The sensitivity analysis of the process depicts the extraction ratio as the key parameter in the computation of vortex tube silt ejector removal efficiency. The findings of the AI-based approaches discussed in the current study might be helpful for hydraulic engineers as well as researchers in the assessment of the removal efficiency of vortex tube silt ejectors.

关键词： Vortex tube silt ejector Support vector machine Random forest Random tree Multivariate adaptive regression spline

An efficient algorithm to clip a 2D-polygon against a rectangular clip window

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Applied Mathematics(A Journal of Chinese Universities) 2022年第1期37卷 147-158页

作者： Sushil Chandra Dimri Umesh kumar tiwari Mangey Ram Department of Computer Science and Engineering Graphic Era(Deemed to be University)DehradunUttarakhandIndia

Polygon clipping is of great importance in computer *** of the popular algorithms to clip a polygon is Cohan–Sutherland Hodgeman algorithm which is based on line ***–Sutherland Hodgeman algorithm clips the polygon against the given rectangular clip window with the help of line clipping ***–Sutherland algorithm requires traversing the polygon in anti clockwise direction(positive orientation).In this work we propose an efficient polygon clipping algorithm against a rectangular clip *** algorithm uses parametric representation of polygon *** the concept of point clipping,we can find required intersection points of edges of polygon with clip window *** suited numerical illustrations are used to explain the proposed polygon clipping *** proposed algorithm is computationally less expensive and comprehensive.

关键词： point clipping polygon clipping clip window line segment computational complexity