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41.
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Random switching techniques for inverter control 总被引:1,自引:0,他引:1
Yen-Shin Lai 《Electronics letters》1997,33(9):747-749
New techniques which dramatically reduce acoustic noise by randomising the inverter switching frequency for inverter control are presented. It is shown that the proposed techniques combine the advantages of conventional pulsewidth modulation (PWM) techniques based on regular-sampling techniques and random PWM techniques 相似文献
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Chen L. Crnic M. Zonghe Lai Johan Liu 《Electronics Packaging Manufacturing, IEEE Transactions on》2002,25(4):273-278
Liquid crystal polymer (LCP) has potentially a very wide application as substrate material in electronic packaging applications because of its unique advantages. The work in this paper was performed to realize the metallization of LCP for the purpose of board fabrication, and to study the adhesion between deposited copper and LCP. A homogenous electroless plated copper layer on LCP with 4 to 5 /spl mu/m thickness was achieved, while it increased up to 40 /spl mu/m with the subsequent electroplating. The timescale of etching, deposit ion rate, and pH value were gradually changing during the plating process and the influences on copper layer quality were investigated. The adhesion force of the copper-LCP layer system was measured by a shear-off-method. Scanning electron microscopy (SEM) was used to check the surface morphology after etching and the interface after shearing on both the backside of the copper layer and the LCP side. The relationship between the shear-off adhesion of copper and the time of chemical etching before plating was examined, and the optimal etching time is discussed. Heat treatment after plating was used, and it was shown that this significantly improved the adhesion strength. 相似文献
46.
Tramadol hydrochloride is a centrally acting synthetic analgesic in widespread clinical use. Despite different degrees of opioid-like characteristics in preclinical tests, it is characterized by lack of full naloxone reversibility or naloxone-precipitated withdrawal in humans. To investigate this apparent discrepancy, the present study measured the affinity of tramadol (and its enantiomers) and an active O-desmethyl metabolite (M1) (and its enantiomers) to cloned human opioid receptors of the mu, delta and kappa type stably expressed in HN9.10 neuroblastoma cells. At mu sites, the Ki values for tramadol, its (+) and (-) enantiomers, M1, and its (+) and (-) enantiomers were 17000, 15700, 28800, 3190, 153 and 9680 nM, respectively, compared to 7.1 nM for morphine. These results are consistent with the suggestion of a non-opioid contribution to the clinical profile of tramadol. 相似文献
47.
Danqing Yi Changhai Li Zonghe Lai O. M. Akselsen J. H. Ulvensoen 《Metallurgical and Materials Transactions A》1998,29(1):119-129
Ternary alloying of MoSi2 with adding a series of transition elements was investigated by X-ray diffraction (XRD), scanning electron microscopy, transmission
electron microscopy (TEM), and energy dispersive spectroscopy (EDS). Iron, Co, Ni, Cr, V, Ti, and Nb were chosen as alloying
elements according to the AB2 structure map or the atomic size factor. The studied MoSi2 base alloys were prepared by the arc melting process from high-purity metals. The EDS analysis showed that Fe, Co, and Ni
have no solid solubility in as-cast MoSi2, while Cr, V, Ti, and Nb exhibit limited solid solubilities, which were determined to be 1.4±0.7, 1.4±0.4, 0.4±0.1, and 0.8±0.1.
Micro-structural characterization indicated that Mo-Si-MVIII (MVIII=Fe, Co, Ni) and Mo-Si-Cr alloys have a two-phase as-cast microstructure, i.e., MoSi2 matrix and the second-phase FeSi2, CoSi, NiSi2, and CrSi2, respectively. In as-cast Mo-Si-V, Mo-Si-Ti, and Mo-Si-Nb alloys, besides MoSi2 and C40 phases, the third phases were observed, which have been identified to be (Mo, V)5Si3, TiSi2, and (Mo, Nb)5Si3. 相似文献
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陈籁民 《建筑科学与工程学报》1996,(2)
基圆半径的确定方法,除了用图解法和试算法外,还可用解析法和图解分析法求解。4种方法各有优缺点,设计时要根据具体情况选择。 相似文献
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许多国家大多没有严格意义上的保健品概念,美国等国家将其统称为“功能食品”。我国应用“保健品”一词,旨在将其与药品和食品两大门类区分开来。美国的“保健品”发展速度和规模比较大,同时由于其先进的制造和科研技术,引领着世界功能食品的潮流。随着我国社会的发展,保健品的生产和研发也逐步赶上国际的步伐,而大量的进口保健品也已经进入寻常百姓家。 相似文献