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81.
This paper considers a two unit cold standby redundant system subject to a single repair facility with exponential failure and general repair time distribution. Each unit can work in three different modes — normal, partial failure and total failure. There is a perfect switch to operate the standby unit on total failure of the operative unit. The system has been analysed to determine the reliability parameters e.g. mean time to system failure (MTSF), steady state availability, mean recurrence to a state and expected number of visits to a state, first two moments of time in transient state, by using the theory of Semi-Markov Process. Howard's reward structure has been super-imposed on the Semi-Markov Process to obtained expected profit of the system. A number of results obtained earlier are derived as particular cases. 相似文献
82.
Ultrafiltration of black liquor was carried out using an asymmetric membrane and the results were compared with that of polyethylene glycol, a standard macromolecule, in a stirred batch cell. The effects of system parameters, e.g., pressure, concentration and stirrer speed on permeate flux and solute rejection were studied extensively for both the solutes.
An osmotic pressure model was used to analyze experimental results. To take into account the phenomena of concentration polarization, an extra resistance term, called the polarization layer resistance (Rp), was incorporated into the model. The polarization layer resistance was found to be a function of flow regime and concentration at the membrane. To correlate these, the following two types of relationship were examined and tested with the experimental results,
and
where a, b, c, a1, b1, are constants. 相似文献
An osmotic pressure model was used to analyze experimental results. To take into account the phenomena of concentration polarization, an extra resistance term, called the polarization layer resistance (Rp), was incorporated into the model. The polarization layer resistance was found to be a function of flow regime and concentration at the membrane. To correlate these, the following two types of relationship were examined and tested with the experimental results,
and
where a, b, c, a1, b1, are constants. 相似文献
83.
The pyrolysis under nitrogen of salt free and salt treated cellulose was studied by infrared spectroscopy. The results confirm the unzipping mechanism suggested by DTA and TGA studies, and show this mechanism to apply to the untreated and salt treated samples. The results also show the unzipping to stop at the stage of char formation. The onset of this stage was found to occur after the volatilization of only 45–50% of the initial sample of the borax treated cellulose, compared with 65–70% of the KCl treated cellulose and 80–85% of the untreated cellulose. 相似文献
84.
A. R. Pal D. P. Motiramani S. B. Gupta B. S. Bhargava 《Nutrient Cycling in Agroecosystems》1990,22(3):129-136
Attempts were made to find out the nature and cause of a widespread sugarcane chlorosis in a cane growing area. Soils from chlorotic and nonchlorotic fields did not differ markedly in pH, CaCO3, electrical conductivity, organic C, and soil test P, Zn, Cu, and Mn levels, but the chlorotic field soils had relatively more NH4OAc-extractable K and less clay and DTPA-extractable Fe. Chlorotic and green leaf blades contained about the same concentration of P, S, Mg, Fe, Zn, Cu, and Mo, but the former leaf blades had more K and less Ca and HCl soluble Fe than the green ones. Green leaves of plants that seemed to have naturally recovered in chlorotic fields were higher in Mn. A foliage spray with 2.5% FeSO4.7H2O solution resulted in greening of leaves and a field experiment showed marked crop response to Fe and some response to Mn. The results thus suggest that the chlorosis is due to a lime-induced Fe-deficiency with the possibility of some role of Mn in Fe nutrition in calcareous soil conditions.Deceased 22 September 1988 相似文献
85.
Analysis of minimum selection H-S/MRC in Rayleigh fading 总被引:1,自引:0,他引:1
We analyze the error performance of an improved hybrid selection/maximal-ratio combining (H-S/MRC) technique called minimum selection H-S/MRC in flat Rayleigh fading for coherent digital modulation schemes. Here the minimum number of diversity branches are selected such that their combined signal-to-noise ratio is above a given threshold. We derive a closed-form expression for the distribution of the number of selected branches. This distribution is used to obtain the symbol error probability. 相似文献
86.
The electrical effects of dislocations has been studied by modeling zero-bias resistance-area product (R0A) of long wavelength infrared diodes fabricated in molecular beam epitaxy (MBE)-grown HgCdTe-Si epitaxial films. Results
show that dislocations influence both 40 K and 78 K R0A products in high dislocation density (HgCdTe/Si) material. In low dislocation density samples (HgCdTe/CdZnTe), the variations
in 78 K R0A are limited by the composition (x) variations in Hg1-xCdxTe material, whereas dislocation contribution dominates the variations at 40 K. The origin of relatively large spread in 40
K R0A in both types of samples is traced to the statistical variations in the core charges of dislocations. It is concluded that
additional alternatives besides the reduction of dislocation density (such as control of core charges), may also need attention
in order to make Si a viable substrate material for the growth of HgCdTe epitaxial layers suitable for devices operating at
40 K. 相似文献
87.
Surendra K. Gupta Manish Sharma Binod Kumar Kanaujia Abhishek Gupta Ganga Prasad Pandey 《Wireless Personal Communications》2014,77(1):633-647
In this paper a novel structure of annular ring loaded stacked circular patch microstrip antenna is theoretically analysed to observe various parameters such as return loss, input impedance, gain, directivity and radiation pattern. It is found that antenna possess three band of operation which signify the compactness and multiband operation of antenna. The antenna is resonating at three operating frequencies 1.720, 2.950, 3.060 GHz. The proposed theory is verified by simulation using Ansoft’s HFSS and theoretical results are in good agreement with simulated results. The antenna is useful for multi-services operations such as WLAN, GSM, UMTS, and WiMAX services. 相似文献
88.
89.
Ashawant Gupta Carmen Cook Len Toyoshiba Jianmin Qiao Cary Y. Yang Ken-Ichi Shoji Akira Fukami Takahiro Nagano Takashi Tokuyama 《Journal of Electronic Materials》1993,22(1):125-128
Characterization of a Si1−xGex layer formed by high-dose germanium implantation and subsequent solid phase epitaxy is reported. Properties of this layer
are obtained from electrical measurements on diodes and transistors fabricated in this layer. Results are compared with those
of the silicon control devices. It was observed that the germanium implantation created considerable defects that are difficult
to eliminate with annealing. These defects result in boron deactivation in the p-type regions of the devices, giving rise
to larger resistance. Optimization of the device structure and fabrication process is discussed. 相似文献
90.
Minimum selection GSC in independent Rayleigh fading 总被引:1,自引:0,他引:1
We analyze the error performance of minimum selection generalized selection combining (MS-GSC), in which the minimum number of diversity branches are selected such that their combined signal-to-noise ratio (SNR) is above a given threshold. A flat Rayleigh fading channel with independent and distinctly distributed branch SNRs is considered. By transforming the ordered instantaneous branch SNRs to their differences, we derive the distribution of the number of selected branches in closed form. We then modify the derivation of this distribution to get the characteristic function (cf.) of the combiner output SNR. This cf. is used to obtain the symbol error probability for different coherent digital modulation schemes. 相似文献