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排序方式: 共有307条查询结果,搜索用时 35 毫秒
21.
Jitendra Dimri 《Computer aided design》2005,37(5):485-495
This paper presents an algorithm for solid model reconstruction from 2D sectional views based on volume-ba`sed approach. None of the existing work in automatic reconstruction from 2D orthographic views have addressed sectional views in detail. It is believed that the volume-based approach is better suited to handle different types of sectional views. The volume-based approach constructs the 3D solid by a boolean combination of elementary solids. The elementary solids are formed by sweep operation on loops identified in the input views. The only adjustment to be made for the presence of sectional views is in the identification of loops that would form the elemental solids. In the algorithm, the conventions of engineering drawing for sectional views, are used to identify the loops correctly. The algorithm is simple and intuitive in nature. Results have been obtained for full sections, offset sections and half sections. Future work will address other types of sectional views such as removed and revolved sections and broken-out sections. 相似文献
22.
Robert B. Grieves Jitendra K. Ghosal Dibakar Bhattacharyya 《Journal of the American Oil Chemists' Society》1968,45(9):591-593
Ion flotation studies have shown that a surface-active agent is useful for qualitative analysis of complex ions in dilute
aqueous solution, with the surfactant forming a particulate complex with the complex ion of concern. Experiments with a monovalent,
cationic surfactant have established the prevalence of Cr2O7
2− (HCrO4
−) and not CrO4
2−; of [Fe(CN)6]4− and [Fe(CN)5H2O]3−; and of [FeFe(CN)6]2− and not [FeFe(CN)6]− or [Fe(CN)6]3−. The results can be contrasted to those with ions that do not form particulate complexes with the surfactant, such as HPO4
2− and phenolate; with the latter, no qualitative analytical information can be gained. Ion flotation appears to be a promising
technique in general for the determination of ionic species present in aqueous solution; the surfactant must react with the
ion of significance to form a particulate complex and the initial surfactant concentration must be controlled carefully. 相似文献
23.
Larry J. Darlage Harry N. Finkbone Samuel J. King Jitendra Ghosal Maurice E. Bailey 《Fuel》1978,57(8):479-484
A series of 34 nitrogen-containing compounds with a wide range of basicities was examined under differential nonaqueous potentiometric conditions in acetophenone and nitrobenzene. These compounds could be resolved into five classes based on pKaand half-neutralization-potential (HNP) values. Asphaltenes isolated from the vacuum still overhead (VSO) and vacuum still bottoms (VSB) fractions of the H-coal process were titrated under similar conditions. The titration results of both asphaltenes indicated the presence of two classes of nitrogen-containing compounds, a titratable class of the pyridine-ring or aniline type and a nontitratable class. 相似文献
24.
Jitendra K. Quamara Anu Sharma Maneesha Garg T. Prabha 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,262(2):215-219
Photoconduction behaviour of 75 MeV oxygen ion irradiated (Fluences: 1.8 × 1011, 1.8 × 1012 and 1.8 × 1013 ions/cm2) kapton-H polyimide film in the visible region has been investigated at different temperatures ranging 400-2500 °C and at various electric fields ranging 40-600 kV/cm. A photoinduced exciton formation is the major source for providing charge carriers through thermolization and field-assisted dissociation processes. An attempt has been made to fit the field dependence of the steady state photocurrent to one of the several possible conduction mechanisms. In the high and low fluence (1.8 × 1013 and 1.8 × 1011 ions/cm2) irradiated samples there exists a possibility of Poole-Frankel type of photoconduction mechanism, whereas at intermediate fluence (1.8 × 1012 ions/cm2) a Schottky type photoconduction mechanism may be operative. The log Ips versus 1/T plots consist of two straight lines with a knee point around 800-1000 °C. The activation energy estimated from the slope of these lines is field dependent varying from 0.40 to 0.73 eV and 0.18 to 0.23 eV above and below the knee point, respectively. This indicates the presence of more than one type of trapping levels in irradiated kapton-H polyimide. 相似文献
25.
During the manufacture of optical fibers using the outside vapor deposition (OVD) process, porous soot preforms are made by depositing soot onto a rotating cylindrical target from a soot-laden flame traversing along the target axis. The dominant mechanism of soot deposition in the OVD process is thermophoresis, which is the tendency of particles to migrate down the local gas temperature gradient. Accurate methods to estimate the heat and mass transfer rates from the flame to the growing preform are critical, as these rates dictate important preform characteristics. The heat and mass transfer during the OVD process are coupled due to particle thermophoresis and growth of the preform. We here present methods to predict the growth rate of a rotating preform along with the evolution of temperature profile at different radial locations within the preform for specified process parameters of flame temperature, burner traverse speed and number of burners. Sensitivity of preform temperature profile and deposition rate to each of the process parameters is presented, along with the critical discussion of our principal results. 相似文献
26.
Wenbo Wang Jitendra Paliwal 《Sensing and Instrumentation for Food Quality and Safety》2007,1(4):193-207
Over the last two decades, near-infrared spectroscopy (NIRS) has established itself as a non-destructive analytical technique
in a variety of disciplines. However, recent technological advancements in hardware design and data mining techniques have
unleashed the potential of NIRS to become a tool of choice for routine analyses of agricultural products. The current paper
synthesizes the status of NIRS in the agri-food industry in terms of hardware and software development as well as the direction
in which the NIRS research is headed. An extensive review of literature reveals that the emphasis on hardware development
is focused on developing compact, robust, and portable spectrometers and hyperspectral imaging (HSI) systems. The software
development on the other hand is geared towards developing better preprocessing, analyses, and modeling techniques using chemometrics,
support vector machines, and artificial neural networks. The four main agri-food sectors identified to be the beneficiaries
of this research revolution are grain quality monitoring; post-harvest handling of fruits and vegetables; identification of
contaminants in animal produce and feed; and food safety and authenticity. Apart from discussing the aforementioned topics,
the paper also provides food scientists some working knowledge on parameters crucial to the performance of spectral and imaging
systems. It is expected that further development of NIRS will help agricultural and food scientists to enhance the quality
and safety of our food. 相似文献
27.
In this mathematical presentation, we examined the significance of Hall current on MHD buoyancy-driven boundary layer flow of a Ti6Al4V-H2O based nanofluid past a vertical surface implanted in a uniform permeable region. The vertical surface is considered to be magnetized and induced magnetic field (IMF) impacts are also considered. The nondimensional flow model is solved with the assistance of the two-term perturbation scheme. Various results are obtained by numerical computation for different significant parameters. These results are presented and analyzed in graphical and tabular form. In the boundary layer domain, the transpiration velocity across the surface tends to diminish the main flow, IMF along the main flow, fluid temperature, and concentration. It is remarkably noted that IMF along the main flow grows for incrementing values of volume fraction coefficient of nanofluid. In the magnetic boundary layer domain, the main flow and IMF along the main flow grow with Hall current. Furthermore, it is seen that for the progressing values of magnetic Prandtl number, the main flow reduces while normal flow and IMF along the main flow is induced in the boundary layer domain. 相似文献
28.
The key objective in this study is to examine the heat and mass transport behavior of magnetohydrodynamic elastic-viscous fluid flow over a vertically oriented magnetized surface placed in a uniform permeable regime with magnetic and thermo diffusions. The fluid is partially ionized and permeated to flow in the presence of a strong magnetic field domain. Hence the Hall current effect is considered in this investigation. The significance of rotation and induced magnetic field on the flowing nature are also scrutinized in this study. The mathematical model of the problem is converted to a similar model by introducing suitable nondimensional variables. To obtain the closed-form solutions of the flow leading equations, the regular perturbation analysis is utilized. For the exhibition of results, figures and tables are generated with the assistance of scientific computation software MATHEMATICA. Computed results are validated with the existing result in the limiting case. Such an investigation is important in evaluating the flow characteristics of low magnetic diffusive viscoelastic fluid. A noteworthy result seen is that magnetic diffusion significantly controls the fluid flow by altering the magnetic drag force. Mass diffusion factor brings an increase in the fluid velocity. Furthermore, we observed that the surface current density along the principal flow direction is significantly reduced by magnetic diffusion and mass diffusion factor. 相似文献
29.
Aqueous sodium and potassium carbonates have been photoreduced in the presence of Toluidine Blue solution (which is also the photocatalyst). The photocatalytic formation of formic acid and formaldehyde was measured spectrophotometrically using Nash reagent. The effect of variation of various parameters like pH, amount of photocatalyst (Toluidine Blue concentration), concentration of Na2CO3 and K2CO3, light intensity, etc., on the yield of photoproducts was also investigated. A tentative mechanism for this reduction has been proposed. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
30.