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排序方式: 共有559条查询结果,搜索用时 171 毫秒
521.
Manoj Kumar AL. Ramanathan Abhijit Mukherjee Ravi Sawlani Shyam Ranjan 《Isotopes in environmental and health studies》2019,55(3):254-271
Stable isotopes of water (δ2H, δ18O) and δ13CTIC were used as a tool to trace the recharge processes, natural carbon (organic and inorganic) source and dynamics in the aquifers of the central Gangetic basin, India. Stable isotope (δ2H, δ18O) record of groundwater (n?=?105) revealed that the groundwater of Piedmont was recharged by meteoric origin before evaporation, while aquifers of the older and younger alluvium were recharged by water that had undergone evaporation loss. River Ganges and its tributaries passing through this area have very little contribution in recharging while ponds play no role in the recharging of adjacent aquifers. The connectivity of shallow aquifers of aquitard formation (comprised of clay/sandy clay with thin patches of fine grey sand), i.e. 25–60?m below ground level (bgl) with the main upper aquifer (at a depth of >120?m?bgl) was found to be higher in older and younger alluvium. Negative values of δ13CTIC (median ?9.6 ‰; range ?13.2 to ?5.4 ‰) and high TIC (median 35?mM; range 31–46?mM) coupled with low TOC (median 1.35?mg/L; range 0.99–1.77?mg/L) indicated acceleration in microbial activity in the younger alluvium, especially in the active floodplain of river Ganges and its proximity. 相似文献
522.
Swati Mukhopadhyay Prativa Ranjan De Krishnendu Bhattacharyya G. C. Layek 《Meccanica》2012,47(1):153-161
A mathematical model is presented for analyzing the boundary layer forced convective flow and heat transfer of an incompressible
fluid past a plate embedded in a Darcy-Forchheimer porous medium. Thermal radiation term is considered in the energy equation.
The similarity solutions for the problem are obtained and the reduced nonlinear ordinary differential equations are solved
numerically. It is noticed that the boundary layer decreases with an increase in the value of inertial parameter and in this
case the temperature profile is found to decrease smoothly within the boundary layer. In case of porous plate, fluid velocity
increases whereas non-dimensional temperature decreases for increasing values of suction parameter. The rate of heat transfer
increases with the increasing values of Prandtl number. The effect of thermal radiation on temperature field is also analyzed. 相似文献
523.
The interaction of a planar shock wave with a spherical density inhomogeneity is studied experimentally under reshock conditions.
Reshock occurs when the incident shock wave, which has already accelerated the spherical bubble, reflects off the tube end
wall and reaccelerates the inhomogeneity for a second time. These experiments are performed at the Wisconsin Shock Tube Laboratory,
in a 9m-long vertical shock tube with a large square cross section (25.4×25.4 cm2). The bubble is prepared on a pneumatically retracted injector and released into a state of free fall. Planar diagnostic
methods are used to study the bubble morphology after reshock. Data are presented for experiments involving two Atwood numbers
(A = 0.17 and 0.68) and three Mach numbers (1.35 < M < 2.33). For the low Atwood number case, a secondary vortex ring appears immediately after reshock which is not observed
for the larger Atwood number. The post-reshock vortex velocity is shown to be proportional to the incident Mach number, M, the initial Atwood number, A, and the incident shock wave speed, W
i. 相似文献
524.
In the present study, computational fluid dynamics (CFD) is used to investigate inspiratory and expiratory airflow characteristics in the human upper respiratory tract for the purpose of identifying the probable locations of particle deposition and the wall injury. Computed tomography (CT) scan data was used to reconstruct a three dimensional respiratory tract from trachea to first generation bronchi. To compare, a simplified model of respiratory tract based on Weibel was also used in the study. The steady state results are obtained for an airflow rate of 45 L/min, corresponding to the heavy breathing condition. The velocity distribution, wall shear stress, static pressure and particle deposition are compared for inspiratory flows in simplified and realistic models and expiratory flows in realistic model only. The results show that the location of cartilaginous rings is susceptible to wall injury and local particle deposition. 相似文献
525.
Namrata Ashutosh Bhardwaj Kirti Ranjan Sudeep Chatterji Ajay K. Srivastava V.K. Verma R.K. Shivpuri 《The European Physical Journal A - Hadrons and Nuclei》2002,13(4):405-410
Multiplicity distributions of charged particles produced in interactions of 800 GeV protons with emulsion nuclei in various
rapidity windows are presented. The data is also analyzed separately for the forward and the backward hemispheres, for rapidity
windows of different widths. It is found that the Negative Binomial Distribution (NBD) describes well the multiplicity distribution
of secondary particles in various rapidity windows and also in both the hemispheres. We have compared the NBD parameters,
in both the hemispheres, at 200 GeV and 360 GeV, with those at 800 GeV. The behaviour of NBD parameters in rapidity windows
of different widths and for different targets has also been studied.
Received: 30 August 2001 / Accepted: 28 January 2002 相似文献
526.
Akhil Ranjan 《Proceedings Mathematical Sciences》1997,107(3):243-250
In this paper we show that a substantial Riemannian submersion ofS 15 with 7-dimensional fibres is congruent to the standard Hopf fibration. As a consequence we prove a slightly weak form of the diameter rigidity theorem for the Cayley plane which is considerably stronger than the very recent radius rigidity theorem of Wilhelm. 相似文献
527.
S Sundar Manoharan Ranjan K SahuD Elefant C.M Schneider 《Solid State Communications》2003,125(2):103-106
We observe a sharp increase in negative magneto-resistance ratio up to 40% for x=0.1, in La0.5Sr0.5Co1−xRuxO3 which is due to the magnetic disorder induced by an anti-ferromagnetic interaction between Co and Ru ions. We also observe a metal to insulator and a ferromagnetic to anti-ferromagnetic transition for 0≤x≤0.3. Ruthenium (IV) ion disrupts an intermediate spin state of cobalt (Co3+:t2g5eg1), forcing a double exchange mediated ferromagnetic state to an anti-ferromagnetic spin state for x≥0.2. 相似文献
528.
529.
A free-falling, spherical, soap-film bubble filled with argon is subjected to a planar M=2.88 shock in atmospheric nitrogen; vorticity is deposited on the surface of the bubble during shock interaction, and the Richtmyer-Meshkov instability ensues. The geometrical development of the shocked bubble is diagnosed with laser sheet imaging and a planar slice showing two cross sections of both the major vortex ring and a secondary vortex ring is revealed experimentally for the first time. Quantitative measurements of the experimental data include the vortex velocity defect, and subsequent circulation calculations, along with a new set of relevant length scales. The shock wave strength, leading to a post-shock compressible regime, allows the study of the instability development in a regime between low Mach number shock tube experiments and high Mach number laser driven experiments that has not been investigated previously. 相似文献
530.
[reaction: see text] A simple synthesis of the 4a-methyltetrahydrofluorene diterpenoids (+/-)-dichroanal B and (+/-)-dichroanone has been achieved through a common hexahydrofluorenone intermediate obtained via Pd(0)-catalyzed reductive cyclization of a substituted 2-(2-bromobenzyl) methylene cyclohexane. 相似文献