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Wyszukujesz frazę "Kumar, K.S." wg kryterium: Autor


Tytuł:
Passerine birds supporting cross pollination in Erythrina stricta Roxb.
Autorzy:
Khanduri, V.P.
Kumar, K.S.
Sharma, C.M.
Riyal, M.K.
Kar, K.
Singh, B.
Sukumaran, A.
Tematy:
Ornithophily
pollination
mating system
geitonogamy
pollen grains
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/2078260.pdf  Link otwiera się w nowym oknie
Opis:
Erythina stricta is an ecologically important tree species in the rainforests of India and its nectar within the flowers contributes to birds’ diet and survival. Reports on the pollination of this species have not been published so far. We therefore explore the reproductive system of this tree species which has great significance to its ecosystem. Birds have an important role in the reproduction of trees through pollination particularly in tropical areas where reproductive success mostly depends on animal pollinator interactions. Study of visitation and nectar feeding behaviour of birds alongwith breeding system assessment of Erythina stricta. Birds visiting and foraging behaviour was observed during Erythrina stricta flowering season in an indian tropical rainforest. Reproductive system was assessed through controlled pollination experiments. Thirteen bird species were recorded visiting and foraging nectar from the flowers of Erythrina stricta. The maximum numbers of visits recorded were from the Red-vented Bulbul (Pycnonotus cafer, Pycnonotidae). The nectar feeding birds were, either (i) potential pollinator with long bills (e.g. Pycnonotus spp., Chloropsis aurifrons, and Dicrurus spp.) or (ii) nectar robbers with comparatively shorter bills (e.g. Zosterops palpebrosa, Stachyris ruficeps, Macronous gularis, Heterophasia glaciris). Controlled pollination experiments revealed high degree of cross pollination (xenogamy) and self-incompatibility in E. stricta. Birds were more frequent in early mornings and their foraging activity was also observed during evening hours; the frequency however, declined with respect to nectar availability. Long corolla tubes of E. stricta could restrict access to nectar collecting bees
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Withania somnifera acts as a potential insect growth regulator in the polyphagous pest, Pericallia ricini
Autorzy:
Gaur, S.K.
Kumar, K.
Tematy:
Withania somnifera
Solanaceae
seed extract
root extract
insect growth regulator
polyphagous pest
Pericallia ricini
Lepidoptera
larva
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Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/65183.pdf  Link otwiera się w nowym oknie
Opis:
Both seed and root extracts of the medicinal plant, Ashwagandha, Withania somnifera exhibit insect growth regulatory activity against the polyphagous pest, Pericallia ricini. Topical administration of W. somnifera seed and root extracts to last instar larvae of P. ricini disrupted moulting and metamorphosis, leading to a number of developmental abnormalities such as delay in larval-pupal and pupal-adult ecdysis, formation of larval-pupal, pupal- -adult and larval-pupal-adult mosaics/chimeras, ecdysial failure, suppression of pupation and adult emergence and formation of abnormal pupae and adultoids. The treatment with seed extracts was more severe than that of root extracts as it completely suppressed the pupation and adult emergence. The results clearly suggest that the medicinal plant, W. somnifera acts as a potential insect growth regulatory (IGR) disrupting the moulting and metamorphosis as a consequence of interference with the endocrine system.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and Characterization of Al-Zn-Mg alloy / Zircon Sand Reinforced Composites
Autorzy:
Satish Kumar, T.
Shalini, S.
Krishna Kumar, K.
Tematy:
Al-Zn-Mg alloy
microstructure
hardness
tensile strength
wear
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Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/351684.pdf  Link otwiera się w nowym oknie
Opis:
Aluminium based metal matrix composite (Al-MMC’s) are much popular in the field like automobile and aerospace industries, because of its ease of fabrication process and excellent mechanical properties. In this study, Al-Zn-Mg alloy composite reinforced with 3, 6 and 9 v % of zircon sand was synthesised by stir casting technique. The microstructure of the composites revealed uniform distribution of reinforced particles. Hardness, tensile strength and wear resistance of Al-Zn-Mg alloy/zircon sand composite were found to increase with increase in v % percentage of zircon sand. Scanning Electron Microscope analysis of wear tested sample surface of composites revealed no evidence of plastic deformation of matrix phase. Particle pulls out and abrasive wear was the common feature observed from all the composites.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unsteady three-dimensional MHD nanofluid flow over a stretching sheet with variable wall thickness and slip effects
Autorzy:
Kumar, G. Vinod
Varma, S. V. K.
Kumar, R. V. M. S. S. K.
Tematy:
pole magnetyczne
magnetohydrodynamika
poślizg
unsteady flow
magnetic field
Buongiorno’s model
variable wall thickness sheet
velocity
thermal and solutal slip
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Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:
https://bibliotekanauki.pl/articles/265665.pdf  Link otwiera się w nowym oknie
Opis:
The stretching sheets with variable thickness may occur in engineering applications more frequently than a flat sheet. Due to its various applications, in the present analysis we considered a three dimensional unsteady MHD nanofluid flow over a stretching sheet with a variable wall thickness in a porous medium. The effects of radiation, viscous dissipation and slip boundary conditions are considered. Buongiorno’s model is incorporated to study the combined effects of thermophoresis and Brownian motion. The dimensionless governing equations are solved by using MATLAB bvp4c package. The impact of various important flow parameters is presented and analysed through graphs and tables. It is interesting to note that all the three boundary layer thicknesses are diminished by slip parameters. Further, the unsteady parameter decreases the hydromagnetic boundary layer thickness.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Scheme for Template Security at Feature Fusion Level in Multimodal Biometric System
Autorzy:
Selwal, A.
Gupta, S. K.
Kumar, S.
Tematy:
feature template
biometric data
feature vectors
multimodal biometrics
fuzzy sets
database
feature fusion
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Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Powiązania:
https://bibliotekanauki.pl/articles/102518.pdf  Link otwiera się w nowym oknie
Opis:
Biometrics is the science of human recognition by means of their biological, chemical or behavioural traits. These systems are used in many real life applications simply from biometric based attendance system to providing security at a very sophisticated level. A biometric system deals with raw data captured using a sensor and feature template extracted from raw image. One of the challenges being faced by designers of these systems is to secure template data extracted from the biometric modalities of the user and protect the raw images. In order to minimize spoof attacks on biometric systems by unauthorised users one of the solutions is to use multi-biometric systems. Multi-modal biometric system works by using fusion technique to merge feature templates generated from different modalities of the human. In this work, a novel scheme is proposed to secure template during feature fusion level. The scheme is based on union operation of fuzzy relations of templates of modalities during fusion process of multimodal biometric systems. This approach serves dual purpose of feature fusion as well as transformation of templates into a single secured non invertible template. The proposed technique is irreversible, diverse and experimentally tested on a bimodal biometric system comprising of fingerprint and hand geometry. The given scheme results into significant improvement in the performance of the system with lower equal error rate and improvement in genuine acceptance rate.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design and Evaluation of the Thermal Properties of Di-, Tri- and Tetra-Azido-Esters
Autorzy:
Kumar, S.
Kumar, A.
Yamajala, K. D. B.
Gaur, P.
Kumar, D.
Banerjee, S.
Tematy:
azido-esters
energetic plasticizers
DFT
contact angle
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Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Powiązania:
https://bibliotekanauki.pl/articles/358266.pdf  Link otwiera się w nowym oknie
Opis:
A group of polycyclic and aliphatic azido-esters (as energetic plasticizers) have been synthesized by simple synthetic routes and their molecular structures were confirmed by spectroscopic techniques. In addition, their thermal and rheological properties have been determined utilizing DSC, TGA, viscosity, and contact angle. Computational studies of these plasticizers have been performed by means of DFT (B3LYP/6-31G*) to estimate possible stable structures, energies, heat of formation, bond dissociation energies, IR and NMR spectra etc. Their compatibility with glycidyl azide polymer (GAP) binder was studied to explore their applicability in propellants. All of these molecules are novel and have been synthesized with the possibility of scale up.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Linear stability analysis for ferromagnetic fluids in the presence of magnetic field, compressibility, internal heat source and rotation through a porous medium
Autorzy:
Kumar, K.
Singh, V.
Sharma, S.
Tematy:
ferrofluids
rotation
magnetic field
porous medium
heat source
compressibility
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Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Powiązania:
https://bibliotekanauki.pl/articles/279562.pdf  Link otwiera się w nowym oknie
Opis:
The effects of magnetic field and heat source strength on thermal convection of a compressible rotating ferromagnetic fluid through a porous medium are investigated theoretically using linear stability theory. A normal mode analysis method is employed to find solutions for the fluid layer confined between parallel planes with free boundaries. The cases of stationary and oscillatory instabilities are discussed. For the stationary state, compressibility, medium porosity and temperature gradient due to heat source have destabilizing effects, whereas rotation and ratio of magnetic permeability delay the onset of convection. The magnetic field and medium permeability have both stabilizing and destabilizing effects under certain conditions. The variations in the stationary critical thermal Rayleigh number and neutral instability curves in (Ra1, x)-plane for various values of physical parameters are shown graphically to depict the stability characteristics. The sufficient conditions for the non-existence of overstability are obtained and the principle of exchange of stabilities holds true in the absence of magnetic field and rotation under certain conditions.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical study on two dimensional distribution of streamwise velocity in open channel turbulent flows with secondary current effect
Autorzy:
Mohan, S.
Kundu, S.
Ghoshal, K.
Kumar, J.
Tematy:
velocity distribution
open channel flow
turbulent flow
RANS equations
secondary current
finite difference method
Pokaż więcej
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Powiązania:
https://bibliotekanauki.pl/articles/38616700.pdf  Link otwiera się w nowym oknie
Opis:
For studying mechanism of sediment transport in river flows, open channel flow is a prototype. Flow has always three components of velocity for all types of channel geometry and for a time independent uniform flow along streamwise or main flow direction, all the components of velocity are functions of lateral and vertical coordinates. The present study investigates the two dimensional distribution of streamwise (or longitudinal) velocity starting from the Reynolds averaged Navier–Stokes equation for a turbulent open channel flow which is steady and uniform along the main flow direction. Secondary flows both along the vertically upward direction and along the lateral direction are considered which are also taken as functions of lateral and vertical coordinates. Inclusion of the secondary current brings the effect of dip phenomenon in the model. The resulting second order partial differential equation is solved numerically. The model is validated for all the cross-sectional, transverse and centreline velocity distribution by comparing with existing relevant set of experimental data and also with an existing model. Comparison results show good agreement with data as well as with the previous model proving the efficiency of the model. It is found that the transverse velocity distribution depends on the formation of circular vortex in the cross-sectional plane and becomes periodic as the number of circular vortex increases for increasing aspect ratios.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fundamental solution in micropolar viscothermoelastic solids with void
Autorzy:
Kumar, R.
Sharma, K. D.
Garg, S. K.
Tematy:
micropolar thermodiffusion
steady oscillations
visothemoelastic
micropolar with void
drgania
termosprężystość
funkcje elementarne
Pokaż więcej
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:
https://bibliotekanauki.pl/articles/265845.pdf  Link otwiera się w nowym oknie
Opis:
In the present article, we construct the fundamental solution to a system of differential equations in micropolar viscothermoelastic solids with voids in case of steady oscillations in terms of elementary functions. Some basic properties of the fundamental solution are also established.
Dostawca treści:
Biblioteka Nauki
Artykuł

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