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31.
Sushil Kumar M. A. Majeed Khan M. Zulfequar M. Husain 《Journal of Materials Science》2007,42(1):363-367
The fabrication of devices with lead salts and their alloys with detecting and lasing capabilities has been an important technological
development. The high quality polycrystalline thin films of PbTe1−x
S
x
with variable composition (0 ≤ x ≤ 1) have been deposited onto ultra clean glass substrates by vacuum evaporation technique. Optical, structural and electrical
properties of PbTe1−x
S
x
thin films have been examined. Absorption coefficient and band gap of the films were determined by absorbance measurements
in wavelength range 2,500–5,000 nm using FTIR spectrophotometer. Sample nature, crystal structure and lattice parameter of
the films were determined from X-ray diffraction patterns. DC conductivity and activation energy of the films were measured
in temperature range 300–380 K through I–V measurements. 相似文献
32.
A Fourier Series Generalized Geometry-Based Analytical Model of Switched Reluctance Machines 总被引:2,自引:0,他引:2
A novel invertible generalized flux/current switched reluctance machine (SRM) model based on the Fourier series expansion is presented. This model, which is derived from machine geometry and materials properties, is accurate enough to be used for actual machine representation and can also be simplified for real-time controller applications. Simulation and experimental results illustrate that the proposed modeling approach provides better representation of the SRM than other existing techniques 相似文献
33.
This paper presents the modeling, simulation, and control aspects of four-quadrant switched reluctance motor (SRM) drives. The design of SRM drive systems must be focused on application-based appropriate control and engineering solutions needed to overcome the practical issues. A complex model is described for the physical motor simulation to incorporate the important dynamics of the SRM. A simpler, but quite accurate, model is presented for the SRM controller. Various practical limitations have been incorporated in the simulation model to make it closer to the experimental setup. The SRM control parameters are chosen based on torque-per-ampere maximization requirement. Experimental results for a 1.0-kW SRM obtained on a digital platform are presented along with useful guidelines for prototype implementation. 相似文献
34.
Yaniv Gelbstein Boaz Dado Ohad Ben-Yehuda Yatir Sadia Zinovy Dashevsky Moshe P. Dariel 《Journal of Electronic Materials》2010,39(9):2049-2052
The search for alternative energy sources is presently at the forefront of applied research. In this context, thermoelectricity
for direct energy conversion from thermal to electrical energy plays an important role. This paper is concerned with the development
of highly efficient p-type Ge
x
Pb1−x
Te alloys for thermoelectric applications, using spark plasma sintering. The carrier concentration of GeTe was varied by alloying
of PbTe and/or by Bi2Te3 doping. Very high ZT values up to ~1.8 at 500°C were obtained by doping Pb0.13Ge0.87Te with 3 mol% Bi2Te3. 相似文献
35.
36.
Rehan Sadiq Tahir Husain Brian Veitch Neil Bose 《The International journal of environmental studies》2013,70(4):313-323
Drilling muds or fluids used in drilling operations serve several functions: they lubricate the drill bit; maintain borehole pressure; clean and condition the hole; and flush rock cuttings to the surface. Drilling mud also adheres to rock cuttings, as can formation oil. Barite is used as a weighting agent, which approximately makes up approximately 33% of synthetic mud. It contains traces of heavy metals, which contribute to the toxicity of drilling waste. As environmental issues attract increasing public awareness, the treatment and disposal of spent drilling fluids and contaminated rock cuttings from drilling operations have become sensitive issues for offshore operations around the world. Within the last decade, the oil and gas industry has introduced synthetic-based drilling fluids as substitutes for oil-based fluids. This pollution prevention measure has been complemented by improvements in solid control systems technology. This paper adopts the current U.S. Environmental Protection Agency methodology for a hypothetical case study of an oil field on the East Coast of Canada to determine the water quality impacts of disposal of drilling wastes. The concentration of pollutants at the edge of the mixing zone in the water column and pore water are estimated and compared with Canadian water quality guidelines for protection of aquatic life. 相似文献
37.
R. Tyagi M. Bal M. Singh Satish Mohan T. Haldar A. Naik Premveer Singh M. Husain S. K. Agarwal 《Solar Energy Materials & Solar Cells》2003,76(3):257-261
Hydrogen passivation on MOCVD grown p-GaAs epilayers on Ge substrate have been studied by plasma and catalytic hydrogenation and the results were compared. The conversion efficiency of the GaAs/Ge solar cells was found to increase by 10% after catalytic hydrogenation at AM1.5. This increase in efficiency is probably due to passivation of surface dangling bonds. 相似文献
38.
Ehsani M. Husain I. Ramani K.R. Galloway J.H. 《Power Electronics, IEEE Transactions on》1993,8(2):224-230
A modified converter topology for star-connected switched reluctance motors suitable for low-voltage applications is proposed. A dual-time-constant freewheeling circuit has been designed to improve the drive performance and efficiency over a wide range of speeds. The different modes of operation of the converter are discussed, and a comparison is made with other converter configurations 相似文献
39.
Fault-tolerant switched reluctance motor drive using adaptive fuzzy logic controller 总被引:5,自引:0,他引:5
Mir S. Islam M.S. Sebastian T. Husain I. 《Power Electronics, IEEE Transactions on》2004,19(2):289-295
An adaptive fuzzy controller has been designed to develop a high-performance fault-tolerant switched reluctance motor (SRM) drive. The fuzzy controller continuously adapts its properties to regulate the machine torque as desired by the drive system even under fault conditions. The adaptation of the fuzzy membership functions results in extended conduction period and increased peak current of the healthy phases to deliver the commanded torque, as much as possible. The adaptive fuzzy controller provides smooth torque output with minimum ripple, even under fault conditions, yielding a high-performance SRM drive with fault-tolerant capability. 相似文献
40.
We examined the mechanical properties of bone in ovariectomized rats treated with tiludronate. 186 Sprague-Dawley (SD) rats, 6 months of age, were assigned to 13 groups and were maintained for 3-9 months after surgery. Ovariectomy (ovx) groups were given tiludronate orally at the respective doses of 0 (vehicle), 12.5 (low), 25 (medium), and 50 (high) mg/kg body weight daily for 3 months beginning 3 months after surgery. Rats were killed at 0 (start), 3, 6, and 9 months. Whereas bone mineral density (BMD) values of the midfemur did not increase after ovx, the values in the sham-operated groups increased age-dependently. Bending moment to failure of the femur in the sham group was larger than that of the ovx control group at 9 months. In the ovx control groups, the ultimate compressive load values of the third lumbar body were reduced compared with those in the sham groups at 3 months and thereafter. Although serum osteocalcin levels were decreased in the medium- and high-dose tiludronate groups, both serum PTH and 1,25(OH)2D levels were increased only in the high-dose group. Femoral BMD, mechanical properties, and the cortical bone area were increased by the high dose at 9 months. Lumbar ultimate compressive load and the circumscribing cortical shell area in the high-dose group were increased at 6 months and thereafter. The trabecular number values were maintained at 6 and 9 months by the high dose. These data demonstrate that tiludronate administration increased the mechanical properties of bone by preserving the age-dependent increases in the cortical bone mass and three-dimensional structure of trabecular bone. These effects seemed to be due to reduced bone turnover by the agent. 相似文献