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1.
In this work, simple n-type electrode structures were used to enhance the electrical and optical performances of fully packaged commercially mass-produced vertical-geometry light-emitting diodes (VLEDs). The forward bias voltage of the VLED with a Y-pattern electrode increased less rapidly than that of VLEDs with a reference electrode. The VLEDs with the reference and Y-pattern electrodes exhibited forward voltages of 2.93±0.015 and 2.89±0.015 V at 350 mA and 3.77±0.015 and 3.53±0.015 V at 2000 mA, respectively. The VLEDs with the Y-pattern electrode resulted in a higher light output than the VLEDs with the reference electrode with increase in the drive current to 2000 mA. The emission images showed that the VLEDs with the Y-pattern electrode exhibited better current spreading behavior and lower junction temperatures than the VLEDs with the reference electrode. With increase in the current from 350 to 2000 mA, the VLEDs with the Y-pattern electrode experienced a 39.4% reduction in the wall plug efficiency, whereas the VLEDs with the reference electrode suffered from a 43.3% reduction. 相似文献
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Joaquim Pérez-Losada Elena Roget Xavier Casamitjana 《Canadian Metallurgical Quarterly》2003,129(9):734-737
High vertical wave-number modes clearly dominate the internal wave field during the stratification period in Boadella reservoir in northeast Spain. In this period, the extraction of hypolimnetic water, due to summer irrigation, brought the surface level down by 6 m in one month and the epilimnetic water progressively occupied the whole water column. The temperature profile, with the exception of a few meters at the surface layer, presented an almost constant temperature gradient of about 0.7°C/m. The period of the main vertical mode is 24 h with an amplitude of around 1 m. Thermistor chain records and meteorological data allow us to deduce that this mode is, at least, a third vertical mode forced by the wind, which normally has a typical periodicity of 24 h. However, when the wind changes direction from south to north, the circulation cells developed due to this forced nonstationary oscillation are destroyed. When this occurs, the Bulk Richardson number is Rib ~ 1. Similar vertical structures as a response to wind forcing should be expected in similar systems, although this has not been reported in the literature. 相似文献
5.
KMLS型立式砂泵的振动噪声产生原因及解决措施 总被引:1,自引:1,他引:0
针对KMLS型立式砂泵振动、噪声产生原因及其表现特征,提出了解决措施。通过对这些原因的分析研究,可以提供泵设计者和生产者在减少砂泵振动方面采取相应的措施,使KMLS型立式砂泵能更好的服务于用户。 相似文献
6.
Obtaining shorter regular expressions from finite-state automata 总被引:1,自引:0,他引:1
We consider the use of state elimination to construct shorter regular expressions from finite-state automata (FAs). Although state elimination is an intuitive method for computing regular expressions from FAs, the resulting regular expressions are often very long and complicated. We examine the minimization of FAs to obtain shorter expressions first. Then, we introduce vertical chopping based on bridge states and horizontal chopping based on the structural properties of given FAs. We prove that we should not eliminate bridge states until we eliminate all non-bridge states to obtain shorter regular expressions. In addition, we suggest heuristics for state elimination that leads to shorter regular expressions based on vertical chopping and horizontal chopping. 相似文献
7.
P. T. Tsilingiris 《国际能源研究杂志》1991,15(9):723-730
The paper describes the calculation of the beam solar radiation transmission across the uniform salinity upper convecting zone (UCZ) and the salinity stratified gradient zone (GZ), when the extinction coefficient is not only wavelength but also salinity-concentration dependent, assuming that the effect of scattering to be negligible. The results are useful in determining the effects of dissolved salt ions on pure water transmission, at least according to the existing measured data in the literature. 相似文献
8.
G. Bretschko 《河流研究与利用》1992,7(1):17-22
The ‘hyporheic zone’ is described. According to the classical definition, water below the sediment surface is groundwater and the hyporheic interstitial zone is part of the phreatic system. This ignores the vertical distribution of the epigeic benthic fauna. The uppermost layer of the sediment (bed sediments) of the hyporheic zone is dominated by epigeic faunal elements and is therefore part of the surface system. In contrast to hypogeic species, the depth penetration of epigeic species is limited. Possible explanations are discussed. 相似文献
9.
Equal Strain Consolidation by Vertical Drains 总被引:1,自引:0,他引:1
Chin Jian Leo 《Canadian Metallurgical Quarterly》2004,130(3):316-327
This paper shows the development of a series of closed-form solutions of equal strain consolidation in the presence of a vertical drain with smear and well resistance. Using an approach that considers the effects of both the radial and vertical drainage in a fully coupled fashion, solutions are obtained for the excess pore pressure and the degree of consolidation in the compressible soil subjected to a step- or ramp-loading situation. The closed-form solutions in the present paper may be evaluated in an electronic spreadsheet on a standard personal computer. 相似文献
10.
阐述了气力提升系统的组成、原理、选择原则和设计过程。并对气力提升系统与传统提升装置进行了分析、比较,指出气力提升系统具有设备性能稳定、耗能小等优点,有着很好的应用前景,值得推广。 相似文献