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61.
Ritayan Chatterjee Dinabandhu Ghosh 《Metallurgical and Materials Transactions B》2013,44(5):1049-1054
A Ghatshila chalcopyrite concentrate (average particle size, 50 μm) containing primarily CuFeS2 and SiO2 (Cu 16 pct, Fe 26 pct, S 14 pct, Si 5 pct, and O 33 pct) was reduced by a stream of hydrogen in a horizontal tube furnace at 1323 K (1050 °C), producing a mixture of Cu (26 pct), SiO2, Fe2O3, Fe3O4, Cu2O, and Fe. Subsequent acid leaching with 1 M HCl solution of the reduction product removed all iron oxides and iron, and other impurities too, leaving a Cu (53.3 pct) + SiO2 mixture, with a small percentage of Cu2O in it. This result compares well with the predicted final mixture of Cu (59 pct)-SiO2 based on a mass balance on the starting concentrate. Elemental chemical analyses were done by energy-dispersive X-ray spectroscopy, which were crosschecked by atomic absorption spectroscopy in the majority of cases. The phase identification and microstructural characterization of Cu-SiO2 mixtures were done by X-ray diffraction, Fourier transform infrared spectroscopy, Rietveld analysis, scanning electron microscopy, and high-resolution transmission electron microscopy (HRTEM). It was found that Cu-SiO2 composites were formed in the final product, with a copper grain size of 385 nm. 相似文献
62.
63.
S. C. Tripathy
S. Bandopadhyay
J. K. Chatterjee
《International Journal of Electrical Power & Energy Systems》1989,11(4):248-252Fast-acting energy storage devices can effectively damp electromechanical oscillations in a power system, because they provide storage capacity in addition to kinetic energy of the generator rotor, which can share the sudden changes in power requirement. Earlier studies showed the effectiveness of superconducting magnetic energy storage (SMES) for this purpose. The present paper analyses the characteristics of lossy magnetic energy storage (LMES) and shows the effectiveness of small-sized LMES units in improving power system transient response. Computer studies show that the optimal parameter settings of the power system are changed with the addition of an energy storage element. 相似文献
64.
Wavelet domain analysis for identification of vehicle axles from bridge measurements 总被引:2,自引:0,他引:2
Bridge weigh-in-motion (B-WIM) is a process by which the axle and gross vehicle weights of vehicles travelling at highway speeds can be determined from instrumented bridges. The traditional method of attaching strain transducers to the soffit of the bridge and placing axle detectors on the road surface has been replaced here by using additional transducers underneath the bridge for axle detection and nothing-on-the-road (NOR). This paper presents a wavelet based analysis of strain signals and shows the efficacy of using wavelets in pattern recognition of these signals. The transformed signals are used to identify axle passage and hence the vehicle velocity and the axle spacing. In addition to numerically generated strains, signals acquired from such a NOR instrumentation of a bridge in Slovenia have been analysed by the method of wavelet transformation to extract axle position information that was not readily detectable using existing methods. 相似文献
65.
Research efforts were given towards development of low carbon high strength steels since recent past. The present study deals with the development of a low carbon high strength steel alloyed with Mn, Ni, Mo, Cu and microalloyed with Ti and Nb. The steel was subjected to three stage controlled rolling operation followed by accelerated cooling. The structure and properties of the steel at various processing conditions were evaluated. Microstructural observation reveals predominantly lath martensite along with twinned martensite structure at all processing conditions. High strength values at higher finish rolling temperatures have been obtained due to fine martensitic structure along with tiny precipitates of microalloying carbide and carbonitride. The strength value increases marginally at lower finishing temperature due to comparatively finer lath size of martensite and increased precipitation density of carbides, carbonitrides along with Cu particles. The variation in impact toughness properties at different finish rolling temperatures is found to be negligible at ambient and subambient temperatures. The formation of stable and large TiN/TiCN particles during casting have impaired the impact toughness values at ambient and at ‐40°C temperatures. 相似文献
66.
This paper describes the swing-up and stabilization of a cart–pendulum system with a restricted cart track length and restricted control force using generalized energy control methods. Starting from a pendant position, the pendulum is swung up to the upright unstable equilibrium configuration using energy control principles. An “energy well” is built within the cart track to prevent the cart from going outside the limited length. When sufficient energy is acquired by the pendulum, it goes into a “cruise” mode when the acquired energy is maintained. Finally, when the pendulum is close to the upright configuration, a stabilizing controller is activated around a linear zone about the upright configuration. The proposed scheme has worked well both in simulation and a practical setup and the conditions for stability have been derived using the multiple Lyapunov functions approach. 相似文献
67.
Chemically deposited zinc oxide thin film gas sensor 总被引:4,自引:0,他引:4
Zinc oxide (ZnO) thin films were prepared by a low cost chemical deposition technique using sodium zincate bath. Structural characterizations by X-ray diffraction technique (XRD) and scanning electron microscopy (SEM) indicate the formation of ZnO films, containing 0.05–0.50 m size crystallites, with preferred c-axis orientation. The electrical conductance of the ZnO films became stable and reproducible in the 300–450 K temperature range after repeated thermal cyclings in air. Palladium sensitised ZnO films were exposed to toxic and combustible gases e.g., hydrogen (H2), liquid petroleum gas (LPG), methane (CH4) and hydrogen sulphide (H2S) at a minimum operating temperature of 150 °C; which was well below the normal operating temperature range of 200–400 °C, typically reported in literature for ceramic gas sensors. The response of the ZnO thin film sensors at 150 °C, was found to be significant, even for parts per million level concentrations of CH4 (50 ppm) and H2S (15 ppm). 相似文献
68.
Annals of Telecommunications - This paper reviews two hybrid (frequency domain) finite element methods for electromagnetic scattering applications. Specifically, the progress over the last five... 相似文献
69.
A K Chatterjee 《Bulletin of Materials Science》1993,16(6):453-464
Three generally accepted generic groups of competitive engineering materials—metals, inorganic ceramics, as well as plastics
and polymers belonging to the organic family—have been comparatively reviewed in the context of raw materials availability,
energy requirements in production, engineering properties, combustibility and environmental friendliness. The intrinsic advantages
of inorganic materials have been discussed. The shortcomings of engineering properties of inorganic materials and the new
technologies of making chemically bonded ceramics or biomimic compounds from inorganic materials with improved toughness have
been dealt with. The expanding application horizons of inorganic materials have been illustrated with the help of several
novel products. 相似文献
70.
The design details of a 0.254 m stainless steel cylindrical fluidized bed pilot plant facility, whose fabrication, installation and testing have been recently completed, are described. It primarily consists of a fluidized-bed reactor, fluidizing air-supply system, solids feeder, off-gas cleaning and exhaust system, and cooling water-supply system for heat-transfer tubes provided in the bed and in the freeboard sections. The plant is operated at ambient pressure in the temperature range 300–600 K, both in the batch and continuous modes for solids feed. Bed-pressure drop measurements as a function of fluidizing velocity for two different bed heights reveal that the quality of fluidization is good. Similar experiments have been conducted with the continuous solids feed. The heat-transfer coefficient between the bed and an immersed stainless steel U-tube is measured as a function of fluidizing air velocity at five different temperatures. The effects on bed-to-tube heat-transfer rate of solids feed rate, bed height, air-flow rate, and bed temperature are examined. All of these observed variations are interpreted in terms of the solids mixing and bubble mechanics in the bed. 相似文献