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131.
P V Ananthapadmanabhan A V Bapat A K Das B K Karan R Majumder R K Marwah D S Patil S V K Rao V K Rohatgi K G Sankaran P Satyamurthy R Sharma P B Shrivastava M K Totlani N Venkat-Ramani F A Akopov A V Karpukhin V V Kirillov V I Maksimenko A S Prokop A I Romanov B V Roshin E V Shishkov A S Tikhotsky V I Zalkind N I Antonov V V Brajevsky D K Burenkov V A Efremov V N Sukhov 《Sadhana》1982,5(3):169-195
This paper summarizes the major results of the joint Indo-Soviet experiment for testing the Indianmhd generator channel section, designed and fabricated at the Bhabha Atomic Research Centre, Bombay, which was carried out at the U-02 facility in Moscow, USSR, in May 1980. The total test duration was 65 hours and included electrophysical tests and life tests under applied electric fields. The main purpose of the tests was to substantiate the physical concepts, computer codes, design features and special processing techniques involved in the development ofmhd generators for the Indian pilot plant at Tiruchirapalli. The experimental observations on the phenomena of heat transfer to the walls, gas dynamics in the channel, electrical characteristics of the generator and near-electrode processes including the analysis of arc spots correlate with the theoretical estimates based on present understanding of the physical processes occuring in similarmhd generators. The post-operational inspection of the channel section and extensive investigation of materials through microscopic analysis, chemical analysis and x-ray analysis are also reported in this paper. The joint test programme has clearly demonstrated the definite operating capability of the test section and has given sufficient information and encouragement for building better and improved channels for the future. 相似文献
132.
Kuttan Prabhakaran Jorly Joseph Nitin Madhusudan Gokhale Suresh Chandra Sharma Ramji Lal 《Journal of the American Ceramic Society》2006,89(7):2335-2337
Nanocrystalline lanthanum strontium manganite (LSM) powder has been synthesized by combustion of a transparent gel obtained by the polymerization of methylol urea and urea in a solution containing La3+ , Sr2+ , and Mn2+ (LSM ions). Chemistry of the transparent urea–formaldehyde (UF) polymer gel formation and structure of the gel have been proposed such that the LSM ions act in between the growing UF polymer chains by interacting through NH, OH, and CO groups by co-ordination and prevent polymer self-assembly through inter-chain hydrogen bonding as evidenced from infrared spectrum. Thermally stable structures formed by the decomposition of UF polymer below 300°C undergo combustion in the presence of nitrate oxidant in a temperature range from 350°–450°C. A perovskite LSM phase has been formed by self-sustained combustion of the dried gel initiated with little kerosene. The powder obtained after deagglomeration and calcination at 600°C for 2 h has a D 50 value of 0.19 μm, and the particles are aggregates of crystallites 10–25 nm in size. 相似文献
133.
D. Patidar R. Sharma N. Jain T. P. Sharma N. S. Saxena 《Bulletin of Materials Science》2006,29(1):21-24
Chemical method has been used to prepare cadmium sulphide by using cadmium, hydrochloric acid and H2S. The reflection spectra of covered and uncovered sintered films of CdS have been recorded by ‘Hitachi spectrophotometer’
over the wavelength range 300–700 nm. The energy band gaps of these films have been calculated from reflection spectra. It
is found that the energy band gap of both films is same as 2.41 eV. It is indicated that energy band gap of these films does
not change. This value of band gap is in good agreement with the value reported by other workers. The measurement of photocurrent
has also been carried out using Keithley High Resistance meter/ Electrometer. This film shows the high photosensitivity and
high photocurrent decay. Thus so obtained films are suitable for fabrication of photo detectors and solar cells. 相似文献
134.
M. Darvizeh H. Haftchenari A. Darvizeh R. Ansari C.B. Sharma 《Composite Structures》2006,74(4):495-502
A calculation of overall dynamic response of thin orthotropic cylindrical shells is presented. Due to the obvious importance of the effects of transverse shear deformation and rotary inertia, these terms are included in the analysis. The exact method is modified to predict the dynamic behavior of an orthotropic circular cylindrical shell. The modal forms are assumed to have the axial dependence in the form of a simple Fourier series. By using the present modified exact analysis various aspects such as influence of boundary conditions, changes in shell geometrical parameters, changes in the directions of orthotropy, etc., on the frequencies, mode shapes and modal forces are studied. Analytical results are shown to be in good agreement with some available experimental and theoretical results. 相似文献
135.
Design of fair surfaces over irregular domains is a fundamental problem in computer-aided geometric design (CAGD), and has
applications in engineering sciences (in aircraft, automobile, ship science etc.). In the design of fair surfaces over irregular
domains defined over scattered data, it was widely accepted till recently that the classical Delaunay triangulation be used
because of its global optimum property. However, in recent times it has been shown that for continuous piecewise linear surfaces,
improvements in the quality of fit can be achieved if the triangulation pattern is made dependent upon some topological or
geometric property of the data set or is simply data dependent. The fair surface is desired because it ensures smooth and
continuous surface planar cuts, and these in turn ensure smooth and easy production of the surface in CAD/CAM, and favourable
resistance properties. In this paper, we discuss a method for construction of C1 piecewise polynomial parametric fair surfaces which interpolate prescribed ℜ3 scattered data using spaces of parametric splines defined on H3 triangulation. We show that our method is more specific to the cases when the projection on a 2-D plane may consist of triangles of zero area, numerically stable and robust, and computationally inexpensive and fast. Numerical
examples dealing with surfaces approximated on plates, and on ships have been presented. 相似文献
136.
Shafai L. Sharma S.K. Daneshmand M. Mousavi P. 《Antennas and Propagation, IEEE Transactions on》2006,54(5):1467-1473
In this paper, the far-field phase shift properties of microstrip patch antennas are investigated. It is shown that, similar to reflectarrays, the resonant nature of microstrip patches can be used to change the phase of the radiated field. This phase change can be caused by the dimensional change of the microstrip patch, or by a reactive loading of its cavity such as an aperture on its ground plane. However, the available phase shift is limited by the antenna impedance bandwidth. The problem is initially investigated for conventional patch antennas, determining the available phase shift range. It is then studied for a wideband E-slot microstrip antenna, showing a considerably larger phase shift range. Then, a micro-electro-mechanical (MEM) based ground plane membrane, activated by an electrode from below, is proposed to adaptively generate and control the required phase shifts. It provides a low loss, continuously variable phase shifter that can be used at high frequencies for beam scanning in small arrays. 相似文献
137.
Halari Rozmin; Hines Melissa; Kumari Veena; Mehrotra Ravi; Wheeler Mike; Ng Virginia; Sharma Tonmoy 《Canadian Metallurgical Quarterly》2005,119(1):104
Sexually dimorphic cognitive performance in men (n=42) and women (n=42) was related to testosterone, estradiol, progesterone, luteinizing hormone, follicle-stimulating hormone, and sex hormone binding globulin, measured in 10-ml blood samples collected between 0900 and 1030 and, among women, during the follicular phase of the menstrual cycle. Significant sex differences favored men on spatial tasks (Mental Rotation and Judgment of Line Orientation) and on an inhibition task and favored women on a verbal task (category fluency). However, there were no significant relationships between any of the hormones and cognitive performance, suggesting that there are few, if any, consistent, substantial relationships between endogenous, nonfluctuating levels of gonadal hormones or gonadotropins and these cognitive abilities in men or women. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
138.
Dheerendra Kumar Dwivedi A. Sharma T. V. Rajan 《Materials and Manufacturing Processes》2005,20(5):777-791
In this paper, the influence of silicon particle morphology on mechanical properties of two piston alloys has been reported. Alloys having nominal composition Al-12%Si-1%Ni-0.8%Cu-0.6%Mg (LM13) and Al-17%Si-1%Ni-0.8%Cu-0.6%Mg (LM28) were prepared by melting and casting. The morphology of silicon crystals was changed using additives during the melt treatment and subsequently by heat treatment. Mechanical properties such as hardness, ductility, and tensile strength of experimental alloys were tested. Test results showed that the melt treatment and heat treatment of both the alloys increased the tensile strength, hardness, and ductility. However, the influence of melt treatment on mechanical properties was not as significant as that of heat treatment. Tensile strength and ductility of LM13 was found to be higher than the LM28 alloy under similar conditions. Hardness of LM28 was higher than the LM13 alloy. Optical and SEM studies showed a change in eutectic silicon morphology on melt treatment of LM13. However, change in morphology of primary silicon particles was not significant as for LM28. Heat treatment of both alloys caused spheroidization and better distribution of eutectic silicon crystals. Sharp-edged primary silicon particles were rounded off after the heat treatment of LM28. Scanning electron microscopy (SEM) of tensile fractured surfaces was carried out to study the influence of microstructure on fracture mode. Heat treatment of both alloys promotes dimple fracture. However, as-cast and melt-treated alloys show predominantly cleavage fracture. 相似文献
139.
A new approach for dynamic job scheduling in mesh-connected multiprocessor systems, which supports a multiuser environment, is proposed in this paper. Our approach combines a submesh reservation policy with a priority-based scheduling policy to obtain high performance in terms of high throughput, high utilization, and low turn-around times for jobs. This high performance is achieved at the expense of scheduling jobs in a strictly fair, FCFS fashion; in fact, the algorithm is parameterized to allow trade-offs between performance and (short-term) POPS fairness. The proposed scheduler can be used with any submesh allocation policy. A fast and efficient implementation of the proposed scheduler has also been presented. The performance of the proposed scheme has been compared with the FCFS policy, the only existing scheduling strategy for meshes, to demonstrate the effectiveness of the proposed approach. Simulation results indicate that our scheduling strategy outperforms the FCFS policy significantly. Specifically, our strategy significantly reduces the average waiting delay of jobs over the FCFS policy. The fast implementation of the proposed scheduler results in low allocation and deallocation time overhead, as well as low space overhead 相似文献
140.
In this paper thermally stimulated luminescence (TSL) studies of BaB4O7 compound are reported for the first time. The polycrystalline sample of BaB4O7 was prepared by a melting method and the formation of the BaB4O7 compound was confirmed by an X-ray diffraction study. The compound has orthorhombic structure at room temperature. The TSL glow curves of BaB4O7 compound when heated at a constant heating rate of 4°C/s exhibit two thermoluminescence (TL) glow peaks at 110 and 150°C followed by a shoulder around 210°C. The trapping parameters associated with the prominent glow peak of BaB4O7 are reported using isothermal luminescence decay method (ILDM). As a check the trap parameters are also calculated by glow curve shape (Chen's) method after isolating the prominent glow peak by thermal cleaning technique. Our results show a very good agreement between the trapping parameters calculated by the two methods. 相似文献