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51.
For a two-dimensional gas flow in a thin film of variable thickness, hydrostatic pressure can be calculated using finite element methods. The load variations related to the bearing configurations and the operating conditions are investigated. Spherical and conical hydrostatic bearings with gas pockets are analysed with constant pressure in the pocket inlet as the boundary condition. The variation of load-carrying capacity with various eccentricities is investigated. The valid regimes that produce normal bearing performance are obtained through the necessary restrictions on the related parameters. 相似文献
52.
An efficient and fast technique for designing Lp approximation filters using the iterative reweighted least-squares (IRLS) algorithm is proposed. This technique introduces an extra frequency response which implicitly includes the weighting function such that the filter coefficients can be obtained with O(N2) complexity 相似文献
53.
The solubility of methane in 3 kmol/m3 solutions of monoethanolamine, diethanolamine, and triethanolamine was measured from 25° to 125°C and pressures up to about 13 MPa. Measurements were also made for the solubility of methane in water at 25° to 125°C and pressures up to 18 MPa in order to confirm the accuracy of the experimental technique. It is demonstrated that methane is more soluble (in terms of mole fraction) in the amine solution than in pure water. Furthermore, the solubility is an increasing function of the size of the alkanolamine. The solubility data were modeled using a Henry's-law approach and the results summarized in terms of salting-in coefficients. 相似文献
54.
Wen-Jung Chiang Hurng-Liahng Jou Jinn-Chang Wu Kuen-Der Wu Ya-Tsung Feng 《Electric Power Systems Research》2010
This paper proposes an active islanding detection method incorporated into the control of the grid-connected inverter to protect the photovoltaic generation system from the islanding operation. The proposed active islanding detection method performs the grid-connected inverter as a virtual resistor with the operation frequency slightly higher or lower than the fundamental frequency of the utility voltage. The function of virtual resistor will not be actuated when the utility is nominal, and the grid-connected inverter can convert the DC power from the solar array to an AC power. When the strong utility is lost, the grid-connected inverter acts as a virtual resistor with the operation frequency slightly higher or lower than the fundamental frequency of the utility voltage. Thus, the frequency and the amplitude of the local load voltage will be away from their normal values under the islanding operation. Hence, the proposed active islanding detection method can immediately detect the islanding operation. A prototype is developed and tested to demonstrate the performance of the proposed active detection method. Both computer simulation and experimental results verify that the performance of the proposed active islanding detection method is expected. 相似文献
55.
A high-efficiency pure white organic light-emitting diode was fabricated with lifetime approaching that of the low-excitation-energy (yellow) emitter containing counterpart, or six times that of the deep-blue counterpart. The white device was composed of two emission layers with mixed hosts of different compositions. They were respectively doped with yellow rubrene and deep-blue 4,4'-bis-[4-{N,N,N',N'- tetrakis-(4-fluoro-diphenylamino)-phenyl}-vinyl]-biphenyl. The resulting efficiency was 6.0 lm/W (12.4 cd/A) at 20 mA/cm(2). The long device lifetime may be attributed to the double mixed-host architecture employed that effectively dispersed the injected carriers into three different recombination zones and consequently diluted the damaging effect arising from the accumulated charge from un-recombined carriers, hence leading to a markedly improved lifespan. 相似文献
56.
The compound S-equol (4′,7-dihydroxy-isoflavandiol), a gut bacterial metabolite of isoflavone daidzein, benefits health, but only 20–60% of humans can produce equol after ingesting isoflavones, and it exists only in foods of animal origin in trace amounts. A recent study found a source of stinky tofu contained S-equol. As stinky tofu is a popular traditional fermented soy food in Taiwan, we analyzed S-equol contents of commercial samples, surveyed the intake frequency, and investigated the bioavailability of S-equol by monitoring urinary kinetics following ingestion. Our results showed 91% of the 138 stinky tofu dishes contained S-equol. The mean content per serving (average 198 g) was 2.3 ± 2.5 mg, the highest being 16.3 mg. Stinky tofu eaters on average ingested this food 3.3 times per month. S-equol from ingested stinky tofu appeared in urine within 1 h, reaching maximum excretion at 3.4 h, and 67% of the ingested S-equol was recovered in urine, indicating a rapid and high absorption. Our studies suggest stinky tofu can be a promising dietary source of S-equol for its high content and bioavailability. Further study on the S-equol producing bacteria in stinky tofu is merited for the development of other S-equol rich soy products. 相似文献
57.
Kuen-Der Wu Hurng-Liahng Jou Ti-Hsin Wang 《International Journal of Electronics》2013,100(9):1113-1123
This paper presents a new amplitude detection method for three-phase sinusoidal signals. The proposed detection method is based on calculation of the Park transformation. This method measures the amplitude of three-phase signals instantaneously and the ideal and non-ideal conditions are analysed. An electronic circuit for implementing this method is developed and tested to demonstrate the performance of the proposed method. 相似文献
58.
Jinn-Chang Wu Hurng-Liahng Jou Pei-Hsuan Huang I-Husan Chiu 《International Journal of Electronics》2013,100(10):1567-1582
The interleaved boost power converter has the advantages of ripple cancellation and better efficiency. The major problem of the interleaved boost power converter is the current balancing among different phases of the boost power converters. In this paper, a current balancing control method for equalizing the currents of two-phase interleaved boost power converter is proposed. The output current can effectively detect the mismatch between the boost power converters for the interleaved boost power converter. The output current is used to perform both the current balance and the current-mode control. The salient feature is that only one current sensor is used in the proposed current balancing control method. A hardware prototype is developed, and the experimental results verify the performance of the proposed current balancing control method is as expected. 相似文献
59.
The performance and stability of a PEMFC depends on many operating parameters. The measurement of local currents in PEMFC cells is an important tool for diagnoses and development of fuel cells. In this study, a segmented cell was developed, which could serve as an essential instrument to investigate the different operating conditions in the cells and stacks of technical relevance. In addition, the effects of different feed gas humidity and temperatures were investigated to analyze the steady-state performance, uniformity, and the local stability of PEMFC with the use of eight segmented regions. With this research method, the resistance in each segment could be measured by ac impedance as well as make a comparison between Nafion® 117 and 112 membranes in PEMFC. In the experiment, by probing into the high frequency internal resistance and performance of this cell, the effects of flow rates of fuels, oxidants, relative humidity, and directional channel flows were investigated for performance and stability of local segmented regions. The results of the experiments demonstrate that the local current distribution is strongly influenced by the relative humidity of fuel, the stoichiometric of the processed air, and the mode of operation. The cell was operated at a cell temperature of 50 °C with low relative humidity of 33% and 0%, causing the drying of the membrane (and increase of its resistance) at the top-stream path. The membrane conductivity was enhanced due to the water product increase by the reaction in the middle- and down-stream paths, because the down-stream has higher current than the top-stream. The relative humidity of the air increased along the path due to the product water, therefore, the current density increased as well. The local segmented cell could maintain stable performance at low hydrogen stoichiometry of 1.05 for low humidity gases. As the counter-flow and inverse gravity direction of hydrogen fuel was operated, the fuel cell showed the much more stable and uniform local performance. 相似文献
60.
Electromagnetic shielding of nylon-66 composites applied to laser modules was studied experimentally and theoretically. The
effects of conductive carbon fiber length and weight percentage upon the shielding effectiveness (SE) of nylon composites
were investigated. The SE of long carbon fiber filled nylon-66 composites was found to be higher than short carbon fiber composites
under the same weight percentage of carbon fibers. In addition, higher electromagnetic shielding was obtained for the composite
with higher carbon fibers contents at the same length. The SE of conductive carbon fiber filled nylon-66 composites was measured
to be 42 dB at a low frequency of 30 MHz and 50 dB at a high frequency of 1 GHz. The SE predicted by theoretical models and
measured by experiments were in good agreement for filled nylon-66 composites with different length fiber. 相似文献