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91.
In photovoltaic (PV) applications, a maximum power point tracking (MPPT) module is necessary to extract the whole energy that the PV module can generate depending on the instantaneous conditions of the PV system. A PV module is obtained by connecting a number of solar cells in series and parallel, which causes voltage and current to increase at module terminations. The present work is based on a three-phase grid-connected inverter designed for a 100 kW PV power plant that uses an MPPT scheme based on fuzzy logic controllers. The whole system presented is simulated in MATLAB. The fuzzy logic-based MPPT controllers show accurate and fast responses and are integrated into the inverter, so that the there is no requirement for a dc–dc converter. The inverter allows full control of reactive power. 相似文献
92.
This paper describes the application of R&M concepts to computer performance evaluation. The relevance of reliability to maintenance cost of computer system is established. Although a simple reliability model is used, one can use more complex models. The mathematical model for maintenance cost analysis must be tailored for individual cases, depending upon the maintenance philosophy of the organization. The computer performance analysis from maintenance view points should examine software reliability and recovery procedures, which are relatively difficult in distributed processing. 相似文献
93.
94.
95.
S. Chatterji 《Cement and Concrete Research》1986,16(6):967-970
A freshly made Portland cement paste is a very unusual fluid. It behaves like a colloidal suspension, although cement particles are much coarser than conventional colloid size. The origins of this colloidal behaviour of a cement paste have been traced to high density and high viscosity of the paste itself. Its high density and viscosity hinder the sedimentation of cement grains and allow for the colloid behaviour to develop. 相似文献
96.
Five different "HIS tag" mutants of cowpea mosaic virus were made by genetically introducing six contiguous histidine residues at various locations on the virus capsid. The mutant particles showed differential affinity for binding nickel, and their electrostatic properties could be controlled as a function of the protonation state of the exposed histidine sequence. The specific addressability of the HIS tag was corroborated by the selective modification of the histidine sequence with nanogold cross-linked to the Ni-NTA moiety. 相似文献
97.
C. K. Mukhopadhyay S. Venugopal T. Jayakumar S. L. Mannan Baldev Raj B. Chatterji R. Srinivasan V. Gopalakrishnan G. Madhusudan R. S. Tripathi 《Materials and Manufacturing Processes》2007,22(7):887-892
Acoustic emission (AE) generated during open die and closed die forging processes of Al alloy has been studied. AE generated during both types of the forging processes could be differentiated into three stages, namely, yielding of the workpiece material upon start of forging, intermediate deformation and filling of the die. The effect of lubrication on the AE generated during open die forging was also studied. This showed that AE increases with decreasing lubrication of the workpiece thus enabling AE to detect lubrication inadequacy/breakdown during the forging process. 相似文献
98.
A. Damgaard Jensen S. Chatterji P. Christensen N. Thaulow H. Gudmundsson 《Cement and Concrete Research》1982,12(5):641-647
The alkali-silica reactivity of 35 different sand types have been evaluated by both the “German” and NaCl bath methods. The results show that although there is a general correlation between the results of these two methods, the evaluations of sand by the two methods are not identical. Analyses of the procedures show the reasons and indicate that the salt bath method is preferable.The results also indicate that the use of a low alkali cement in conjunction with a reactive aggregate may not protect a concrete sample if sosium salts, from an outside source, can migrate and concentrate in it. 相似文献
99.
C. K. Mukhopadhyay S. Venugopal T. Jayakumar S. L. Mannan Baldev Raj B. Chatterji R. Srinivasan V. Gopalakrishnan G. Madhusudan R. S. Tripathi 《Materials and Manufacturing Processes》2006,21(5):543-549
Optimization of a sensor location for effective characterization of a hot forging process using acoustic emission (AE) signals is discussed in this paper. Acoustic emission signals generated during forging operations on an aluminium alloy were recorded using three sensors simultaneously by mounting them on the top bolster, bottom bolster, and bottom die of the press. The AE signals with maximum sensitivity could be detected with a sensor attached to the bottom die in preference to the other positions. Using AE parameters, the forging process could be differentiated into three regions, i.e., 1) yielding of the workpiece material, 2) intermediate deformation region, and 3) filling of the die. The results show that the optimum position of the AE sensor for monitoring hot forging is found to be the bottom die of the forging press. 相似文献
100.
S. P. Ravindranathan K. T. Kashyap S. Ravi Kumar C. Ramachandra B. Chatterji 《Journal of Materials Engineering and Performance》2000,9(1):24-27
The effect of delayed aging on mechanical properties is characteristically found in Al-Mg-Si alloys. “Delayed aging” refers
to the time elapsed between solutionizing and artificial aging. Delayed aging leads to inferior properties. This effect was
investigated in an Al-Cu-Mg alloy (AU2GN) of nominal composition Al-2Cu-1.5Mg-1Fe-1Ni as a function of delay. This alloy also
showed a drop in mechanical properties with delay. The results are explained on the basis of Pashley’s kinetic model to qualitatively
explain the evolution of a coarse precipitate structure with delay. It is found that all the results of delayed aging in the
Al-Cu-Mg alloys are similar to those found in Al-Mg-Si alloys. 相似文献