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81.
Nayan Patel Mehmet Krta Vaidya Sankaran Suresh Menon 《Proceedings of the Combustion Institute》2007,31(2):2327-2334
Large-eddy simulation (LES) of a liquid-fueled lean-direct injection (LDI) combustor is carried out by resolving the entire inlet flow path through the swirl vanes and the combustor. A localized dynamic subgrid closure is combined with a subgrid mixing and combustion model so that no adjustable parameters are required for both non-reacting and reacting LES. Time-averaged velocity predictions compare well with the measured data. The unsteady flow features that play a major role in spray dispersion, fuel–air mixing and flame stabilization are identified from the simulation data. It is shown that the vortex breakdown bubble (VBB) is smaller with more intense reverse flow when there is heat release. The swirling shear layer plays a major role in spray dispersion and the VBB provides an efficient flameholding mechanism to stabilize the flame. 相似文献
82.
A 6.71 kW power tiller was evaluated for draft and drawbar power on tar roads. The effect of mounting 40 kg of wheel ballast was also studied. Polynomial regression analysis was used to establish the relationship between draft and wheel slip, drawbar power and wheel slip, drawbar power and fuel consumption, and drawbar power and specific fuel consumption. The results of the study showed draft values of 2107, 2110 and 2110 N in second low, third low and first high gears at an engine speed of 150o rpm with a 15% wheel slip. The respective draft values at engine speed of 2000 rpm with a 15% wheel slip were 2172, 2189 and 2212 N. With the mounting of 40kg wheel ballast there was an increase in draft of 217, 207 and 291 N at 1500 rpm, and 328, 306 and 344 N at 2000 rpm of the engine with a 15% wheel slip in second low, third low and first high gears, respectively. The increase in drawbar power with 40 kg ballast was 10.88%, 7.83% and 20.13% at 1500 rpm and 18.89%, 16.56% and 14.88% at 2000 rpm of engine over the drawbar power available with zero ballast. The fuel consumption with the use of wheel ballast was slightly more than the fuel consumption without any ballast. 相似文献
83.
Devendra K. Rastogi Suresh K. Sahni Vidya B. Rana Satendra K. Dua 《Transition Metal Chemistry》1978,3(1):56-60
Summary Dimeric manganese(II)and iron(II)complexes, (ML)2, derived from benzoyl hydrazones ofo-hydroxyaryl aldehydes and ketones arc described and characterised by elemental analyses and by conductance, molecular weight, magnetic, electronic and i.r. spectral measurements. The dimeric nature of the complexes is revealed by i.r. spectra which show bands atca. 885 Mn2+ and 820 cm–1 Fe2+, characteristic of ring vibrations. The i.r. spectra reveal the terdentate nature of the ligands. The electronic spectra in dimethylformamide are consistent with the tetrahedral nature of the complexes. The appreciable lowering in
eff is attributed to the presence of exchange interactions between two paramagnetic atomsvia oxygen bridges.Reprints of this article are not available. 相似文献
84.
The single- and multi-mode Richtmyer–Meshkov instabilities (RMI) with reshock are numerically analyzed in two- and three-dimensional
domains. Four different types of air/SF
6 interface shapes are investigated in a shock tube configuration, and the predicted post-reshock growth rates are compared
with available empirical models of Mikaelian’s (Physica D 36(3):343–347, 1989) and Charakhch’an’s (J Appl Mech Tech Phys 41(1):23–31, 2000). The simulation of 3D multi-mode RMI shows good agreement with a past experimental study, but other interface types (2D
single-mode, 2D multi-mode and 3D single-mode) result in different growth rates after reshock. Parametric studies are therefore
performed to investigate the sensitivities of the post-reshock growth rates to model the empirical parameters. For single-mode
RMI configurations, the interface shape is found to be only a weak function of the post-reshock growth rate, as also predicted
by previous reshock models. The post-reshock growth rate shows a linear correlation to the velocity jump due to reshock; however,
it is only about a half of the prediction of Charakhch’an’s model even though the growth before reshock compares well with
pre-reshock models. The 3D single-mode post-reshock RMI growth rate is nearly 1.6 times larger than the 2D single-mode RMI.
The parametric studies of multi-mode RMI show two distinctly different growth rates depending on the mixing conditions at
reshock. If the interface remains sharp at the time of reshock, the post-reshock growth rate is as large as the single-mode
cases. However, if the interface is mixed due to non-linear interactions of bubbles and spikes, the growth rates becomes slow
and independent of the interface shapes. Overall, this study provides new insights into the flow features of reshocked RMI
for different initial perturbation types. 相似文献
85.
Twenty three at‐risk high school female students who had failed mathematics and science in a traditional school setting were the subjects of this study that integrated mathematics and science lessons over a period of four weeks. Using a combination of direct instruction, calculations, graphing, hands‐on projects, and discussion, the topic of mechanical advantage was studied, to find out how well students understood the topic. The study found that these students who initially knew very little about mechanical advantage, and who did not see any need to use mathematics in the study of science, indicated an increased understanding of mechanical advantage, and also seemed to realize that integrating mathematics and science enhanced learning. 相似文献
86.
Suresh K. Sahni 《Transition Metal Chemistry》1979,4(2):73-76
Summary Complexes of 2,6-dipicolinic acid hydrazide, DPH, with ZnII, CdII and HgII have been prepared and characterized by elemental analysis, i.r. and electronic spectra and by electrical conductance measurements. The ligand is terdentate, having coordination sites at two deprotonated amide-nitrogen and pyridine-nitrogen atoms. The ZnII and HgII complexes are pentacoordinate whereas the CdII complexes are hexacoordinate and have trigonal bipyramidal and pseudooctahedral stereochemistries, respectively. The Zn, Cd and Hg ions induce cyclization of DPH complexes upon reaction with-diketones. The complexes of macrocyclic ligands so formed have the same stereochemistries as those of DPH. 相似文献
87.
Das P Mandal AK Kesharwani MK Suresh E Ganguly B Das A 《Chemical communications (Cambridge, England)》2011,47(26):7398-7400
A receptor with acidic methylene hydrogens is found to act as an efficient binding mode for F(-). This reagent could as well be used for selective and quantitative extraction of F(-) from the aqueous solution of NaF and sea water. 相似文献
88.
Poly(vinyl chloride) (PVC)-based membrane of pentathia-15-crown-5 exhibits good potentiometric response for Hg2+ over a wide concentration range (2.51 × 10−5 to 1.00 × 10−1 mol dm−3) with a slope of 32.1 mV per decade of Hg2+ concentration. The response time of the sensor is as fast as 20 s. The electrode has been used for a period of six weeks and exhibits fairly good discriminating ability towards Hg2+ in comparison to alkali, alkaline and some heavy metal ions. The electrode can be used in the pH range from 2.7 to 5.0. 相似文献
89.
The paper presents a spatially homogeneous and anisotropic Bianchi type-I cosmological model consisting of a dissipative fluid.
The field equations are solved explicitly by using a law of variation for mean Hubble parameter, which is related to average
scale factor and yields a constant value for deceleration parameter. We find that the constant value of deceleration parameter
describes the different phases of the evolution of universe. A barotropic equation of state (p=γ
ρ) together with a linear relation between shear viscosity and expansion scalar, is assumed. It is found that the viscosity
plays a key role in the process of the isotropization of the universe. The presence of viscous term does not change the fundamental
nature of initial singularity. The thermodynamical properties of the solutions are studied and the entropy distribution is
also given explicitly. 相似文献
90.
D.M. Raj KumarM. Manivel Raja K. PrabaharV. Chandrasekaran Asok PoddarR. Ranganathan K.G. Suresh 《Journal of magnetism and magnetic materials》2011,323(13):1750-1754
The effect of Si/Ge ratio on resistivity and thermopower behavior has been investigated in the magnetocaloric ferromagnetic Gd5SixGe4−x compounds with x=1.7-2.3. Microstructural studies reveal the presence of Gd5(Si,Ge)4-matrix phase (5:4-type) along with traces of secondary phases (5:5 or 5:3-type). The x=1.7 and 2.0 samples display the presence of a first order structural transition from orthorhombic to monoclinic phase followed by a magnetic transition of the monoclinic phase. The alloys with x=2.2 and 2.3 display only magnetic transitions of the orthorhombic phase. A low temperature feature apparent in the AC susceptibility and resistivity data below 100 K reflects an antiferromagnetic transition of secondary phase(s) present in these compounds. The resistivity behavior study correlates with microstructural studies. A large change in thermopower of −8 μV/K was obtained at the magneto-structural transition for the x=2 compound. 相似文献