975 resultados para RGB color pattern
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两相流动不稳定性是在各种水力学直径通道内所遇到的复杂现象,这些不稳定性对热能系统可能造成有害影响。本文以丙酮为工质,在受热微通道入口处设置微汽泡发生器,采用脉冲电压激励产生可控微汽泡,并以微汽泡为种子尝试对热微通道内沸腾不稳定性及传热的控制。实验研究表明低频种子汽泡热控能够减轻各参数的脉动幅度;高频种子汽泡热控能彻底抑制沸腾不稳定性;种子汽泡技术的优点是能够在各发泡频率下抑制沸腾不稳定性,强化换热。本研究结果为解决微通道内沸腾不稳定性提供了一种崭新有效的手段,大大延长了待冷却芯片的使用寿命。
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专利是除论文外的又一非常重要的科技成果。目前专利申请工作并未得到足够重视,并且文献中对专利技术成果的反映甚少。文章对中国国家知识产权局(SIPO)专利数据库中海洋能专利授权情况进行了分类统计。介绍了波浪能、潮汐能、温差能的最新专利,并指出了该领域专利申请的热点和空白领域。最后根据统计数据从专利的角度分析了中国海洋能研究的进展和前景。
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太阳能是清洁、可再生能源,是传统化石能源最为重要的替代能源之一。随着全球能源短缺与环境污染的日益加俱,人类开始更加自觉、主动和高效的利用太阳能。太阳能利用技术包括光热利用技术、光电利用技术(又称为“光伏利用技术”)、光化学利用技术,其中光热、光电利用技术已经产业化并开始大规模应用。中国目前是全球最大的光热利用市场,未来中国也将是全球最具发展潜力的光电利用市场。
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从电力能源系统的峰谷差矛盾现状出发,分析了在我国普遍实施冰蓄冷空调系统的必要性。介绍了包括传统的冰球、盘管式冰蓄冷以及新兴的流态化动态冰蓄冷技术的特点。阐述了先进的流态化动态冰蓄冷技术的原理及其应用优势,并介绍了该技术在国内外的研究发展状况。
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用分子动力学(MD)模拟方法系统研究了结构Ⅰ型(SⅠ)和结构H型(SH)氢气水合物中氢气的占据情况并确定了氢气水合物的稳定结构:SⅠ水合物氢气分子数小胞中为2,大胞中为3;SH水合物氢气分子数小胞中为2,中胞中为2,大胞中为11.分析了稳定情况下水合物各胞腔内氢气分子之间的径向分布函数(RDF),得出了氢气分子在各胞腔内的稳定位置.由稳定位置得到了稳定结构下氢气水合物的储氢质量分数:SⅠ为5.085%,SH为6.467%.与实验对比得出结论:SH水合物稳定结构下的储氢能力最强.
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应用阿贝折射仪测量THF(四氢呋哺)溶液的折光率,以此确定THF溶液的组成。实验研究表明,测试数据与文献值吻合良好;THF与水、乙醇及甲醇的两组分溶液折光率与组成之间有很好的规律性,前者可以用抛物线关系式描述,后两者可以用线性关系式描述,其相关系数R在0.99以上,标准偏差SD在0.0015以下,完全适合用于相关溶液组成的测定。
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The objective of this paper is to investigate the effects of channel surface wettability and temperature gradients on the boiling flow pattern in a single microchannel. The test section consists of a bottom silicon substrate bonded with a top glass cover. Three consecutive parts of an inlet fluid plenum, a central microchannel and an outlet fluid plenum were etched in the silicon substrate. The central microchannel had a width of 800 mu m and a depth of 30 mu m. Acetone liquid was used as the working fluid. High outlet vapor qualities were dealt with here. The flow pattern consists of a fluid triangle (shrinkage of the liquid films) and a connected long liquid rivulet, which is generated in the central microchannel in the timescale of milliseconds. The peculiar flow pattern is formed due to the following reasons: (1) the liquid rivulet tends to have a large contact area with the top hydrophilic channel surface of the glass cover, but a smaller contact area with the bottom silicon hydrophobic surface. (2) The temperature gradient in the chip width direction at the top channel surface of the glass cover not only causes the shrinkage of the liquid films in the central microchannel upstream, but also attracts the liquid rivulet populated near the microchannel centerline. (3) The zigzag pattern is formed due to the competition between the evaporation momentum forces at the vapor-liquid interfaces and the force due to the Marangoni effect. The former causes the rivulet to deviate from the channel centerline and the latter draws the rivulet toward the channel centerline. (4) The temperature gradient along the flow direction in the central microchannel downstream causes the breakup of the rivulet to form isolated droplets there. (5) Liquid stripes inside the upstream fluid triangle were caused by the small capillary number of the liquid film, at which the large surface tension force relative to the viscous force tends to populate the liquid film locally on the top glass cover surface.
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Based on the phase-conjugate polarization interference between two one-photon processes. When the laser has broadband linewidth, the sum-frequency polarization beat (SFPB) signal shows the autocorrelation of SFPB exhibits hybrid radiation-matter detuning terahertz damping oscillation. As an attosecond ultrafast modulation process, it can be extended intrinsically to any sum-frequency of energy-levels. It hits been also found that the asymmetric behaviors of the polarization beat signals result from the unbalanced dispersion effects, (c) 2005 Elsevier B.V. All rights reserved.
Resumo:
Based on the phase-conjugation polarization interference between two two-photon processes, we theoretically investigated the attosecond scale asymmetry sum-frequency polarization beat in four-level system (FASPB). The field correlation has weak influence on the FASPB signal when the laser has narrow bandwidth. Conversely, when the laser has broadband linewidth, the FASPB signal shows resonance-nonresonance cross correlation. The two-photon signal exhibits hybrid radiation-matter detuning terahertz; damping oscillation, i.e., when the laser frequency is off resonance from the two-photon transition, the signal exhibits damping oscillation and the profile of the two-photon self-correlation signal also exhibits zero time-delay asymmetry of the maxima. We have also investigated the asymmetry of attosecond polarization beat caused by the shift of the two-photon self-correlation zero time-delay phenomenon, in which the maxima of the two two-photon signals are shifted from zero time-delay point to opposite directions. As an attosecond ultrafast modulation process, FASPB can be intrinsically extended to any level-summation systems of two dipolar forbidden excited states.
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We report the observation of intense spontaneous emission of green light from LiF:F-2:F-3(+) centers in active channel waveguides generated in lithium fluoride crystals by near-infrared femtosecond laser radiation. While irradiating the crystal at room temperature with 405 nm light from a laser diode, yellow and green emission was seen by the naked eye. Stripe waveguides were fabricated by translating the crystal along the irradiated laser pulse, and their guiding properties and fluorescence spectra at 540 nm demonstrated. This single-step process inducing a waveguide structure offers a good prospect for the development of a waveguide laser in bulk LiF crystals.