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Frontiers of structural and Civil Engineering 2022年第8期16卷 1040-1055页

作者： shuvankar das Debarghya CHAKRABORTY Department of Civil Engineering Indian Institute of Technology KharagpurWest Bengal 721302India

In the present study,the stability of a vertical rock escarpment is determined by considering the influence of *** bound finite element limit analysis in association with Power Cone Programming(PCP)is applied to incorporate the failure of rock mass with the help of the Generalized Hoek-Brown yield *** change in stability due to the presence of undercut is expressed in terms of a non-dimensional stability number(σci/γH).The variations of the magnitude ofσci/γH are presented as design charts by considering the different magnitudes of undercut offset(H/vu and wu/vu)from the vertical edge and different magnitudes of Hoek-Brown rock mass strength parameters(Geological strength Index(GsI),rock parameter(mi),Disturbance factor(D)).The obtained results indicate that undercut can cause a severe stability problem in rock mass having poor *** the help of regression analysis of the computed results,a simplified design equation is proposed for obtainingσci/γ*** performing sensitivity analysis for an undisturbed vertical rock escarpment,we have found that the undercut height ratio(H/vu)is the most sensitive parameter followed by GsI,undercut shape ratio(wu/vu),and *** developed design equation as well as design charts can be useful for practicing engineers to determine the stability of the vertical rock escarpment in the presence of *** patterns are also presented to understand type of failure and extent of plastic state during collapse.

关键词： undercut vertical escarpment stability Hoek-Brown yield criterion PCP

Deforestation effects on biological and other important soil properties in an upland watershed of Bangladesh

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Journal of Forestry Research 2014年第4期25卷 877-885页

作者： s.M. sirajul Haque sanatan das Gupta sohag Miah Institute of Forestry and Environmental sciences University of Chittagong Chittagong 4331 Bangladesh Department of Renewable Resources University of Alberta EdmontonCanada Research Fellow Institute of Forestry and Environmental SciencesUniversity of Chittagong Chittagong-4331 Bangladesh

Deforestation occurs at an alarming rate in upland watersheds of Bangladesh and has many detrimental effects on the environment. This study reports the effects of deforestation on soil biological proper- ties along with some important physicochemical parameters of a southern upland watershed ***. soils were sampled at 4 paired sites, each pair representing a deforested site and a forested site, and having similar topographical characteristics. significantly fewer （p〈0.001） fungi and bacteria, and lower microbial respiration, active microbial biomass, metabolic and microbial quotients were found in soils of the deforested sites. soil physical properties such as moisture content, water holding capacity, and chemical properties such as organic matter, total N, avail- able P and EC were also lower in deforested soils. Bulk density and pH were significantly higher in deforested soils. Available Ca and Mg were inconsistent between the two land uses at all the paired sites. Re- duced abundance and＇biomass of soil mesofauna were recorded in defor- ested soils. However, soil anecic species were more abundant in defor- ested soils than epigeic and endogeic species, which were more abundant in forested soils than on deforested sites.

关键词： deforestation effeets biological properties soil animals upland watershed Bangladesh

Effect of interface adhesion factor on the bearing capacity of strip footing placed on cohesive soil overlying rock mass

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Frontiers of structural and Civil Engineering 2021年第6期15卷 1494-1503页

作者： shuvankar das Debarghya CHAKRABORTY Department of Civil Engineering Indian Institute of Technology KharagpurKharagpur 721302India

The problem related to bearing capacity of footing either on pure soil or on pure rock mass has been investigated over the ***,no study deals with the bearing capacity of strip footing on a cohesive soil layer overlying rock ***,by implementing the lower bound finite element limit analysis in conjunction with the second-order cone programming and the power cone programming,the ultimate bearing capacity of a strip footing located on a cohesive soil overlying rock mass is determined in this *** considering the different values of interface adhesion factor(α_(cr))between the cohesive soil and rock mass,the ultimate bearing capacity of strip footing is expressed in terms of influence factor(I _(f))for different values of cohesive soil layer cover ratio(T_(cs)/B).The failure of cohesive soil is modeled by using Mohr−Coulomb yield criterion,whereas Generalized Hoek−Brown yield criterion is utilized to model the rock mass at *** variations of I_(f) with different magnitudes of α_(cr) are studied by considering the influence of the rock mass strength parameters of beneath rock mass *** examine stress distribution at different depths,failure patterns are also plotted.

关键词： bearing capacity soil-rock interface Hoek−Brown yield criterion plasticity limit analysis

A review on transition metal oxides based photocatalysts for degradation of synthetic organic pollutants

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Journal of Environmental sciences 2024年第5期139卷 389-417页

作者： Athira Krishnan Anna swarnalal Divine das Midhina Krishnan Viswanathan s.saji sMAshibli Department of Chemistry Amrita Vishwa VidyapeethamAmritapuriKerala690525India Interdisciplinary Research Center for Advanced Materials King Fahd University of Petroleum&MineralsDhahran31261Saudi Arabia Department of Chemistry University of KeralaKariavattom CampusThiruvananthapuramKerala695581India

This review provides insight into the current research trend in transition metal oxides(TMOs)-based photocatalysis in removing the organic colouring matters from *** easy understanding,the research progress has been presented in four generations according to the catalyst composition and mode of application,viz:single component TMOs(the firstgeneration),doped TMOs/binary TMOs/doped binary TMOs(the second-generation),inactive/active support-immobilized TMOs(the third-generation),and ternary/quaternary compositions(the fourth-generation).The first two generations represent suspended catalysts,the third generation is supported catalysts,and the fourth generation can be suspended or *** review provides an elaborated comparison between suspended and supported catalysts,their general/specific requirements,key factors controlling degradation,and the methodologies for performance *** the plausible fundamental and advanced dye degradation mechanisms involved in each generation of catalysts were *** existing challenges in TMOs-based photocatalysis and how the researchers approach the hitch to resolve it effectively are *** research trends are also presented.

关键词： Photocatalysis Dye degradation Transition metal oxides and composites supported catalysts suspended catalysts

Characterization of electrical properties of AlGaN/GaN interface using coupled schrodinger and Poisson equation

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Journal of semiconductors 2012年第11期33卷 16-23页

作者： s.das A.K.Panda G.N.dash National Institute of science and Technology Palur HillsBerhampurOdisha761008India

The electrical characterization of AlGaN/GaN interface is *** dependence of two-dimensional electron gas（2-DEG） density at the interface on the Al mole fraction and thickness of AIGaN layer as well as on the thickness of GaN cap layer is *** information can be used to design and fabricate AlGaN/GaN based MODFET（modulation doped field effect transistor） for optimum DC and RF characteristics.

关键词： MODFET 2-DEG polarization critical thickness self-heating

Prediction of the residual strength of clay using functional networks

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Geoscience Frontiers 2016年第1期7卷 67-74页

作者： s.Z.Khan shakti suman M.Pavani s.K.das Civil Engineering Department BIETBPUT Civil Engineering Department National Institute of Technology Rourkela

Landslides are common natural hazards occurring in most parts of the world and have considerable adverse economic effects. Residual shear strength of clay is one of the most important factors in the determination of stability of slopes or landslides. This effect is more pronounced in sensitive clays which show large changes in shear strength from peak to residual states. This study analyses the prediction of the residual strength of clay based on a new prediction model, functional networks（FN） using data available in the literature. The performance of FN was compared with support vector machine（sVM） and artificial neural network（ANN） based on statistical parameters like correlation coefficient（R）, Nash–sutcliff coefficient of efficiency（E）, absolute average error（AAE）, maximum average error（MAE） and root mean square error（RMsE）. Based on R and E parameters, FN is found to be a better prediction tool than ANN for the given data. However, the R and E values for FN are less than sVM. A prediction equation is presented that can be used by practicing geotechnical engineers. A sensitivity analysis is carried out to ascertain the importance of various inputs in the prediction of the output.

关键词： Landslides Residual strength Index properties Prediction model Functional networks

Performance analysis of a thick copper-electroplated FDM ABs plastic rapid tool EDM electrode

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Advances in Manufacturing 2018年第4期6卷 442-456页

作者： saroj Kumar Padhi s. s. Mahapatra Rosalin Padhi Harish Chandra das Department of Mechanical Engineering Koneru Lakshmiah Education Foundation Deemed to be University Vaddeswarm 522502 India Department of Mechanical Engineering National Institute of Technology Rourkela Rourkela 76900& India Department of Physics Berhampur University Berhampur 760007 India Department of Mechanical Engineering National Institute of Technology Meghalaya Shillong 793003 India

The importance of rapid tooling (RT) and additive manufacturing (AM) appears to be indispensable for boosting the process of manufacturing and expanding the horizon of production technology worldwide. This concept draws the attention of numerous scholars to arrive at a conclusive theory for the widespread utilization of RT. This study attempts to determine the viability and performance of an RT electrode in the field of electro discharge machining (EDM). The electrode prototype is made using an acrylonitrile butadiene styrene (ABs) plastic by fused deposition modeling (FDM), an AM technique, electroplated with copper of desired thickness, and used in die sinking EDM of D2 steel. The scanning electron microscope analysis of the electroplated samples confirms that it is possible to obtain the desired thickness of the metal by electroplating on any electrically conductive surfaces. In the present work, an experimental study is performed for examining the electroplated copper thickness of the plastic EDM electrode and its performances. It is found that the electroplated ABs plastic EDM RT electrode successfully performs the machining operation of D2 steel, and the results are comparable with a solid electrode. The study reveals that the RT electrode can be regarded as a viable tool for rough cutting or semi-finishing cut EDM functions. The experimental results are thoroughly discussed, examined, analyzed, and evaluated for the purpose of developing the appropriate form of the concept.

关键词： Additive manufacturing (AM) Fused deposition modeling (FDM)-Metallization of acrylonitrile butadiene styrene (ABs) plastic Reduced silver colloidal Rapid tooling (RT) Electro discharge machining (EDM)

Environmental impact of aquaculture-sedimentation and nutrient loadings from shrimp culture of the southeast coastal region of the Bay of Bengal

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Journal of Environmental sciences 2004年第3期16卷 466-470页

作者： Biplob das Yusuf sharif Ahmed Khan Pranab das Department of Earth and Atmospheric sciences Institute of Marine SciencesInstitute of Marine Sciences 1-26 Earth Sciences Building University of Alberta Edmonton Alberta T6G 2E3CanadaUniversity of ChittagongChittagong 4331BangladeshUniversity of ChittagongChittagong 4331Bangladesh

Nutrient loadings were measured for surface seawater and bottom sediments of semi intensive and improved extensive shrimp culture pond, adjacent estuary, and fallow land in the south east coastal region of Bangladesh during August, 2000—January, 2001 to evaluate the impact of shrimp culture. The mean levels of nutrients found in the pond surface water were 108 780 mg/L for CaCO 3, 0 526 mg/L for NH + 4 N, 3 075 wt% for organic carbon, 7 00 mg/L for PO 4 P, 5 57 mg/L for NO 3 N, and 7 33 mg/L for chlorophyll a. The maximum mean value of H 2s(0 232 mg/L) was found in estuarine water. Nutrients loading were found to be decreased with distance from the shrimp farm discharge unit in estuarine water. The mean level of organic matter, total nitrogen, and organic carbon were found in higher concentrations in sediments of cultured pond compared to bottom soil of adjacent fallow land at the same elevation. Extractable Ca values were found in higher concentration(550 33 ppt) in adjacent fallow land, as the shrimps for molting in shrimp ponds use extractable Ca. The relation between seawater H 2s value and sediment pH ( r= -0 94); sediment organic carbon and sediment pH values ( r= -0 76), sediment total nitrogen and sediment pH ( r= - 0 74) were found to be highly negatively correlated. Whereas the relation between seawater H 2s value and sediment total nitrogen ( r= 0 92), water NH + 4 N and sediment pH ( r= 0 66) were found to be positively correlated. The results revealed that load of nutrients at eutrophic level in estuarine water, and decrease of soil pH; leading to acid sulphate soil formation indicates a negative impact of shrimp culture.

关键词： environment eutrophication impact nutrients shrimp culture

Mechanical and low-cycle fatigue behavior of stainless reinforcing steel for earthquake engineering applications

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Earthquake Engineering and Engineering Vibration 2010年第3期9卷 449-457页

作者： Yihui Zhou Yu-Chen OU George C. Lee jerome s. O＇Connor Department of Civil Structural and Environmental Engineering University at Buffalo Buffalo NY U.S.A. Department of Construction Engineering Taiwan University of Science and Technology Taipei Chinese Taiwan Department of Civil structural and Environmental Engineering University at Buffalo Buffalo NY U.S.A. Transportation Research MCEER University at Buffalo Buffalo NY U.S.A.

Use of stainless reinforcing steel （sRs） in reinforced concrete （RC） structures is a promising solution to corrosion issues. However, for sRs to be used in seismic applications, several mechanical properties need to be investigated. These include specified and actual yield strengths, tensile strengths, uniform elongations and low-cycle fatigue behavior. Three types of sRss （Talley s24100, Talley 316LN and Talley 2205） were tested and the results are reported in this paper. They were compared with the properties of A706 carbon reinforcing steel （Rs）, which is typical for seismic applications, and MMFX II, which is a high strength, corrosion resistant Rs. Low-cycle fatigue tests of the Rs coupons were conducted under strain control with constant amplitude to obtain strain life models of the steels. Test results show that the sRss have slightly lower moduli of elasticity, higher uniform elongations before necking, and better low-cycle fatigue performance than A706 and MMFX II. All five types of Rss tested satisfy the requirements of the ACI 318 code on the lower limit of the tensile to yield strength ratio. Except Talley 2205, the other four types of Rss investigated meet the ACI 318 requirement that the actual yield strength does not exceed the specified yield strength by more than 18 ksi （124 MPa）. Among the three types of sRss tested, Talley s24100 possesses the highest uniform elongation before necking, and the best low-cycle fatigue performance.

关键词： stainless reinforcing steel low-cycle fatigue seismic applications corrosion resistance

The phytochemical, biological, and medicinal attributes of phytoecdysteroids: An updated review

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Acta Pharmaceutica sinica B 2021年第7期11卷 1740-1766页

作者： Niranjan das siddhartha Kumar Mishra Anusha Bishayee Eunüs s.Ali Anupam Bishayee Department of Chemistry Iswar Chandra Vidyasagar CollegeBelonia-799155TripuraIndia Cancer Biology Laboratory Department of ZoologySchool of Biological SciencesDr.Harisingh Gour Central UniversitySagar-470003Madhya PradeshIndia Pine View school OspreyFL 34229USA Department of Biochemistry and Molecular Genetics Feinberg School of MedicineNorthwestern UniversityChicagoIL 60611USA Lake Erie College of Osteopathic Medicine BradentonFL 34211USA

The phytoecdysteroids(PEs)comprise a large group of biologically-active plant steroids,which have structures similar to those of insect-molting *** are distributed in plants as secondary metabolites that offer protection against phytophagus(plant-eating)*** insects consume the plants containing these chemicals,they promptly molt and undergo metabolic destruction;the insects eventually ***,ecdysteroids are a group of polyhydroxylated ketosteroids that are structurally similar to *** carbon skeleton of ecdysteroids is termed as cyclopentanoperhydro-phenanthrene with aβ-side chain at *** essential characteristics of ecdysteroids are a cis-(5β-H)junction of rings A and B,a 7-en-6-one chromophore,and a trans(14α-OH)junction of rings C and *** only synthesize PEs from mevalonic acid in the mevalonate pathway of the plant cell using acetyl-CoA as a precursor;the most common PE is *** far,over 400 PEs have been identified and reported,and a compilation of 166 PEs originating from 1998 has been previously *** the present review,we have summarized 212 new PEs reported between 1999 and *** have also critically analyzed the biological,pharmacological,and medicinal properties of PEs to understand the full impact of these phytoconstituents in health and disease.

关键词： Phytoecdysteroids secondary metabolites Antioxidant Anti-inflammatory Antimicrobial Antidiabetic Anticancer activity