检索结果-南通市图书馆

Phytosociology of stratification in a lowland tropical rainforest occurring north of the Tropic of Cancer in Meghalaya, India

在线全文

学校读者我要写书评

暂无评论

Plant Diversity 2019年第5期41卷 285-299页

作者： Uma shankar Department of Botany North-Eastern Hill University

Stratification in lowland rainforests of Meghalaya,India,which represent the westernmost limit of the rainforests north of the Tropic of Cancer,was studied in horizontal and vertical planes to elucidate the patterns in stacking of species diversity and community attributes,and to draw comparisons with rainforests of‘Indo-Malaya’ecozone(biogeographical realm).All individuals≥10 cm GBH(girth at breast height)were enumerated in six transects of 10 m width and up to 500 m length covering 2.45 ha *** stratification of whole assemblage of species in vertical plane is referred to as‘storey structure’(=height class distribution),which explains structural *** horizontal plane,it is typically referred to as‘stand structure’(=girth class distribution),which explains structural *** stratification of an individual species in vertical plane is referred to as‘loftiness’and in horizontal plane,it is frequently referred to as‘population structure’.The stand structure was characterized by a negative exponential relationship or a reverse J-shaped curve,which is typical of a well regenerating forest *** storey structure was characterized by the low stature of the rainforest(<30 m),subtle layering in the canopy with dearth of discrete multi-stories,narrower widths of the stories and a thick *** cluster analysis and‘candlestick charts’showed that the dominant species spatially segregated in canopy height to profile three strata,viz.,an understory of juveniles and shrubs below 5 m,a middle-storey of intermediate trees between 5 and 15 m,and an overstory of large trees between 15 and 25 *** trees of a few species may reach up to 30 *** individuals tended to scatter in increasingly wider range of height classes from a lower to the next higher girth class,creating a‘torchlight scatter’pattern,with a tendency to concentrate towards smaller height classes due to stochastic factors,which potentially influence vertical growth proportionate t

关键词： Forest stratification Stand structure Storey structure Loftiness Population structure Northeast India

The bioinformatics of next generation sequencing:a meeting report

在线全文

学校读者我要写书评

暂无评论

Journal of Molecular Cell Biology 2011年第3期3卷 147-150页

作者： Ravi shankar Studio of Computational Biology&Bioinformatics Institute of Himalayan Bioresource TechnologyCouncil of Scientific&Industrial Research(CSIR)PalampurHimachal PradeshIndia

The Studio of Computational Biology&Bioinformatics(SCBB),IHBT,CSIR,Palampur,India organized one of the very first national workshop funded by DBT,*** India,on the Bioinformatics issues associated with next generation sequencing *** course structure was designed by SCBB,*** workshop took place in the IHBT premise on 17 and 18 June 2010.

关键词： struc India workshop

Rainforests north of the Tropic of Cancer: Physiognomy, floristics and diversity in ‘lowland rainforests’ of Meghalaya, India

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Plant Diversity 2017年第1期39卷 20-36页

作者： Uma shankar Amit Kumar Tripathi Department of Botany North-Eastern Hill University Shillong 793 022 India

The lowland rainforests of Meghalaya, India represent the westernmost limit of the rainforests north of the Tropic of Cancer. These forests, on the Shillong plateau, are akin to Whitmore's ‘tropical lowland evergreen rainforest' formation and exhibit striking similarities and conspicuous differences with the equatorial rainforests in Asia-Pacific as well as tropical seasonal rainforests in southwestern China near the Tropic of Cancer. We found these common attributes of the rainforests in Meghalaya: familial composition with predominance of Euphorbiaceae, Lauraceae, Meliaceae, Moraceae, Myrsiticaceae,Myrtaceae and Rubiaceae; deciduousness in evergreen physiognomy; dominance of mega-and mesophanerophytic life-forms; abundance of species with low frequency of occurrence(rare and aggregated species); low proportional abundance of the abundant species; and truncated lognormal abundance distribution. The levels of stand density and stand basal area were comparable with seasonal rainforests in southwestern China, but were lower than equatorial rainforests. Tropical Asian species predominated flora, commanding 95% of the abundance. The differences include overall low stature(height) of the forest, inconspicuous stratification in canopy, fewer species and individuals of liana, thicker understory,higher proportion of rare species, absence of locally endemic species and relatively greater dominance of Fagaceae and Theaceae. The richness of species per hectare(S) was considerably lower at higher latitudes in Meghalaya than in equatorial rainforests, but was comparable with seasonal rainforests. Shannon's diversity index(H’=4.40 nats for ≥10 cm gbh and 4.25 nats for ≥30 cm gbh) was lower on higher latitudes in Meghalaya in comparison to species-rich equatorial rainforests, but it was the highest among all lowland rainforests near the Tropic of Cancer.

关键词： Lowland rainforest Forest structure Floristics Phytosociology Species richness Life-form spectrum

3D and 2D topographic correction to estimated geothermal gradient from the base of gas hydrate stability zone in the Andaman Forearc Basin

在线全文

学校读者我要写书评

暂无评论

Energy Geoscience

Energy Geoscience 2024年第2期5卷 314-320页

作者： Uma shankar Department of Geophysics Institute of ScienceBHUVaranasiIndia

Methane gas hydrate related bottom-simulating reflectors(BSRs)are imaged based on the in-line and cross-line multi-channel seismic(MCS)data from the Andaman Forearc *** depth of the BSR depends on pressure and temperature and pore water *** these assumptions,the BSR depth can be used to estimate the geothermal gradient(GTG)based on the availability of in-situ temperature *** calculation is done assuming a 1D conductive model based on available in-situ temperature measurement at site NGHP-01-17 in the study ***,in the presence of seafloor topography,the conductive temperature field in the subsurface is affected by lateral refraction of heat,which focuses heat in topographic lows and away from topographic *** 1D estimate of GTG in the Andaman Forearc Basin has been validated by drilling results from the NGHP-01 expedition.2D analytic modeling to estimate the effects of topography is performed earlier along selected seismic profiles in the study *** study extended to estimate the effect of topography in 3D using a numerical *** corrected GTG data allow us to determine GTG values free of topographic *** difference between the estimated GTG and values corrected for the 3D topographic effect varies up to~5℃/*** conclude that the topographic correction is relatively small compared to other uncertainties in the 1D model and that apparent GTG determined with the 1D model captures the major features,although the correction is needed prior to interpreting subtle features of the derived GTG maps.

关键词： Gas hydrate BSR Geothermal gradient 3D and 2D topographic modeling Andaman Forearc Basin

In-plane and out-of-plane quasi-static compression performance enhancement of 3D printed re-entrant diamond auxetic metamaterial with geometrical tuning and fiber reinforcement

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2023年第7期25卷 1-17页

作者： Niranjan Chikkanna shankar Krishnapillai Velmurugan Ramachandran Department of Mechanical Engineering Indian Institute of Technology Madras600036India Department of Aerospace Engineering Indian Institute of Technology Madras600036India

Auxetic materials are cellular materials with a unique property of negative Poisson’s *** auxeticity and performance of these metamaterials utterly depend on the geometrical parameters and loading *** the first time,the quasi-static uniaxial compression performance of fused filament fabricated re-entrant diamond auxetic metamaterial is evaluated in the x-direction(in-plane)and z-direction(out-of-plane).The most commonly used thermoplastic feedstock,Acrylonitrile butadiene styrene,is considered a material of *** effect of influential geometrical parameters of the re-entrant diamond structure and printing parameter is systematically studied using Taguchi’s design of ***-based multi-objective optimisation technique has been adopted to arrive at the optimal *** are made to improve the stiffness and strength of the structure with fibre *** glass fibre reinforcements have enhanced specific strength and stiffness in both in-plane and out-ofplane directions.A sevenfold and thirteen times increase in specific strength and energy absorption is evident for glass fibre-reinforced structures in out-of-plane directions compared to in-plane *** tuning of geometrical parameters of the re-entrant diamond structure can result in a Poisson’s ratio of up to-3.49 when tested in the *** parametric study has illustrated the tailorability of the structure according to the application *** statistical study has signified each considered parameter’s contribution to the compression performance characteristics of the 3D printed re-entrant diamond auxetic metamaterial.

关键词： Auxeticity Fibre reinforcement Tailorability Anisotropy Geometrical influence Property enhancement

Efficacy of diurnal BG-Sentinel traps to capture nocturnal adult Armigeres subalbatus mosquitoes and impact of altitudinal variations in forests

在线全文

学校读者我要写书评

暂无评论

Asian Pacific Journal of Tropical Medicine 2019年第11期12卷 512-519页

作者： Devi shankar Suman Zoological Survey of India New AliporeKolkataWest Bengal700053India

Objective:To establish an efficacious and efficient surveillance method of Armigeres(Ar.)subalbatus,a known filarial vector,surviving in forest habitats to estimate realistic population density and assess the impact of altitudinal variations on the efficacy of the ***:In the study,12 locations in areas with an altitudinal range from 82 m to 920 m were selected in three reserve forests for night sampling of adult *** mosquito using standard chemical lure based BG-Sentinel traps and CDC-light traps in *** of locations and time were estimated on the efficacy of traps as mosquito density using multifactor analysis of variance for significant *** of altitudinal variations on the efficacy of traps was assessed using multiple regression with slope ***:BG-Sentinel trap collected significantly more adult ***,4.43 folds in Gorumara NP,5.19 folds in Neora Valley NP and 12.10 folds in Mahananda WLS than the CDC-light trap irrespective to ***-Sentinel traps were tolerant of altitudinal variations(80 m-170 m)and showed no significant relationship between density and altitudes in contrast to CDC-light traps which showed a significant negative impact on capturing efficacy with increase in altitudes(P<0.001).Conclusions:The study suggests that BG-Sentinel traps can be used effectively and efficiently to collect more *** mosquitoes during night time in comparison to CDC-light trap under complex climatic conditions of forest and variable altitudes.

关键词： Mosquitoes Surveillance Adult mosquito traps Altitudinal variations Armigeres subalbatus

Effect of pellet die diameter on density and durability of pellets made from high moisture woody and herbaceous biomass

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Carbon Resources Conversion 2018年第1期1卷 44-54页

作者： Jaya shankar Tumuluru 750 University Blvd Biofuels DepartmentEnergy Systems LaboratoryIdaho National LaboratoryIdaho FallsID 83415-3750USA

Densified products produced from pellet mill are commercially used as a commodity type product for energy applications that are transported nationally and *** quality of the pelletized biomass produced depends on the process variables such as die diameter,length to diameter(L/D)ratio,die speed,preheating,and steam conditioning;and feedstock variables such as feedstock type,moisture content,and particle size and *** the present study,pelleting tests were conducted with both woody(i.e.,lodgepole pine and pinyon-juniper)and herbaceous(i.e.,corn stover,wheat straw,and energy sorghum)biomass.A high level of feedstock moisture content of 33%(w.b.)was selected,while the die speed and preheating temperature process variables were kept at 60 Hz(380 rpm)and 70*** indicated that during the pelleting and cooling process,an approximate 10–13%(w.b.)moisture loss in both the woody and herbaceous biomass was *** high moisture pellets produced were further dried in a laboratory oven at 70C for three hours to reduce the moisture content of the pellets to1133,>580,>620 kg/m3)and the woody biomass lodgepole pine(e.g.,>1037,>568,>641 kg/m3),*** the case of durability for the 8 mm diameter pellets,wheat straw and corn stover recorded a maximum of about 96%,respectively,while the lodgepole pine and pinion juniper recorded a maximum of>96%,respectively.

关键词： Woody and herbaceous biomass High moisture pelleting Unit Bulk density Tapped density Durability

Alkali activated slag-fly ash concrete incorporating precious slag as fine aggregate for rigid pavements

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Traffic and Transportation Engineering(English Edition) 2022年第1期9卷 78-92页

作者： Avinash Talkeri A.U.Ravi shankar Department of Civil Engineering National Institute of Technology KarnatakaSurathkalMangalore 575025India

This study aims to develop the alkali activated slag-fly ash concrete(AASFC) using precious slag(PS) ball as the fine aggregate. The slag-fly ash proportion, sodium silicate/sodium hydroxide(SS/SH) ratio and sodium hydroxide concentration are the prime variables. The fresh concrete properties like workability, setting time and the hardened concrete properties of AASFC developed under ambient curing were analyzed and similar way by replacing with fly ash(FA). The sodium hydroxide concentration of 8 M, 10 M and 12 M, SS/SH ratio of 1.0, 1.5 and 2.0, alkaline liquid to binder ratio of 0.35 and variation in slag-fly ash proportion as major inputs for mix design. The test results showed that, the fresh state of AASFC blend has a shorter setting time of 12-16 min, because of calcium mineral from the FA, the workability and setting time of AASFC mix was enhanced by the addition of the trisodium phosphate as a retarder. At the higher SS/SH extent, the workability and setting time exaggerated, whereas the increased FA content and sodium hydroxide concentration had a greater influence on the fresh state of concrete. Also, the sodium hydroxide concentration, SS/SH ratio and slag-fly ash proportion are the most inducing parameters on the workability, setting time and strength parameters of AASFC.

关键词： Road engineering Slag-fly ash proportion SS/SH ratio Molarity AASFC PS ball

Frequency domain analysis of pre-stressed elastomeric vibration isolators

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2023年第7期25卷 33-47页

作者： S.Somanath R.Marimuthu shankar Krishnapillai Indian Space Research Organisation Anthariksh BhavanNew BEL RoadBengaluru560231India STR/VSSC Indian Space Research OrganisationThiruvananthapuram695022India Department of Mechanical Engineering IIT MadrasChennai600036India

Two types of elastomeric vibration isolators used for equipment vibration isolation in aerospace vehicles are considered for the present study. These isolators are constructed using elastomers mounted in steel encasings. These isolators are initially deformed statically and dynamic loads are applied on the deformed configuration. To capture the static deformation, equivalent static load corresponding to its load rating and specified displacements are created. Static deformation is computed using Finite Element methods with four node axi-symmetric element which include the geometric non-linear effect for steel and with standard Yeoh hyper-elastic material model for elastomers(Muhammed and Zu, 2012) [1]. Yeoh material constants are derived from uni-axial tension test data of the elastomer specimen. These isolators are subjected to harmonic and random excitations in the pre-deformed state. For numerical analysis, elastomeric constants at dynamic conditions are obtained as complex function of frequency using Dynamic Mechanical Analyzer(DMA) for a range of frequencies. The standard material model of Yeoh is modified incorporating frequency dependant material characteristics and damping in the range of frequencies of interest. A multiplicative non-separable variables law is derived for Yeoh material model to include the effect of static pre-stress, based on the methodology given in literature(Nashif et al.,1985;Beda et al., 2014) [2,3]. The modifications of Yeoh model suitable for frequency domain analysis is the novelty in the present study. In the analysis, while dynamic loads are applied, the configuration is updated considering initial static loading. The frequency response of the isolators is computed using material properties evaluated at progressive dynamic strains until a match in natural frequency is observed. Appropriate damping corrections are then incorporated to match the test observed transmissibility. Then updated material properties are used to compute the

关键词： Elastomer Isolator Axi-symmetric Frequency Random Response Strain amplitude Complex modulus Transmissibility