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151.
The effect of DC flux on the core loss is examined for the practical range of power and frequency. Relevant core loss equations are derived and applied to an optimization algorithm to determine the minimum core loss at a given ratio of s (DC flux density to AC peak flux density). It has been found that the curves of hysteresis loss density versus the ratio of s exhibit a peak at a critical ratio. Below or above this critical ratio, the loss density decreases drastically. On the other hand, the curves of eddy-current loss density versus the ratio of s exhibits a minimum point at a critical ratio. Below or above this critical ratio, the loss density increases gradually 相似文献
152.
Y. C. Lee Ph.D. Nagesh Basavanhally Ph.D. 《JOM Journal of the Minerals, Metals and Materials Society》1994,46(6):46-50
In addition to providing electrical connections, solder is useful in the formation of passive, precision alignments for optoelectronic packaging. Different designs have demonstrated micrometer-level alignment accuracies, and the aligned structures are becoming more and more complex. Solder engineering has been successfully introduced into the field of optoelectronics, and it is expected to be applied to many other areas demanding low-cost, precision alignments. 相似文献
153.
154.
155.
Diphasic gels were prepared by a precipitated process from the mixed solutions of colloidal silica and aluminium nitrate.
High-purity stoichiometric mullite powders were produced by calcination of the products of these gels, with an exothermic
reaction occurring at 1300°C. The chemical and structural evolutions, as a function of thermal treatment, have been characterized
by differential thermal analysis, thermogravimetric analysis, X-ray diffraction, infrared spectroscopy, and electron microscopy.
The components of the co-precipitated gels react independently with increasing temperature up to the formation of mullite.
The composition of mullite also varies with the temperature of thermal treatment. The calcined powders treated by ball-milling
could be sintered into a high-density body, in spite of the occurrence of a small amount of glassy phase during sintering. 相似文献
156.
In this paper, the TRNSYS Simulation Program is used to investigate the monthly and annual solar fraction of a Thermosyphon Solar Water Heater and to evaluate its economic viability in terms of its life cycle savings over a conventional water heating system. The results of the simulation indicate that the yearly solar contribution of the system ranges from 63% for a high hot water consumption profile to 89% for a low consumption pattern. The payback period of the system is as low as 3 years when compared to electric water heating systems. As long as the competitor is diesel oil, the payback period increases to 7–9 years, depending on the hot water consumption profile used. 相似文献
157.
A chimeric dopamine transporter (DAT) cDNA encoding mutant human DAT (hDAT) protein in which the intracellular carboxyl-terminal tail is replaced by that of the bovine dopamine transporter (bDAT) was constructed. The chimeric hDAT cDNA was expressed in COS-7 cells, and [3H]dopamine and [3H]MPP+ uptake and [3H]CFT binding capacities were assessed. Substrate transport and ligand binding of bDAT were reduced by 32-43% as a result of substitution of the carboxyl tail in hDAT, suggesting that the functional characteristics of bDAT arise from differences in the carboxyl tail between human and bovine DAT. Thus, it appears that the sequences encoded within the carboxyl terminal of DAT would be one of the important determinants for its functions. 相似文献
158.
159.
Experimental studies on the aerodynamic coupling effect on natural frequencies and flutter instability of rotating disks
are investigated in this paper. The experiments performed using a vacuum chamber and optical disks give two main results.
One is that the aerodynamic effect by surrounding air reduces the natural frequencies and critical speeds of the vibration
modes in pre-flutter regions. The other is that the natural frequency of the disk rotating at ambient atmospheric pressure
is equal to that in vacuum at the flutter onset speed where the disk experiences aero-induced flutter. In post-flutter regions,
the aerodynamic coupling between the disk and surrounding air increases the natural frequencies of the disk.
Received: 17 June 2002/Accepted: 7 October 2002
The work was supported by Grant No. R11-1997-042-090001-0 of the Center for Information Storage Devices designated by the
Korea Science & Engineering Foundation.
Paper presented at the 13th Annual Symposium on Information Storage and Processing Systems, Santa Clara, CA, USA, 17–18 June,
2002 相似文献
160.
Mathews V.K. Maddox R.L. Fazan P.C. Rosato J. Hwang H. Lee J. 《Electron Device Letters, IEEE》1992,13(12):648-650
Nitrided gate oxides offer several electrical and reliability advantages over conventional oxides and also provide a good barrier against impurity diffusion. Oxidation in nitrous oxide (N2O) has been very successful in overcoming some of the problems associated with nitridation in ammonia. The authors have observed that the extent of N2O oxidation has a strong detrimental effect on the drain leakage current of MOS transistors in the off state. This phenomenon has been identified to be caused by an increase in the active area junction leakage current 相似文献