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471.
Stimulated Brillouin scattering in optical fibers is described by a theoretical model and numerical analysis. The results
showed that, for an optical fiber pumped by a laser beam with ns-order-pulse width and kW-order peak-power, SBS reflectivity
tends to saturate when the fiber length exceeds a limit, named “effective fiber length”. Using small core-diameter and long
enough fiber, the SBS reflectivity level could be raised but is limited by optical damage of the entrance surface of the fiber.
Therefore, just a small dynamic range can be obtained.
Project supported by the Bundesminesterium für Bildung und Forschung (BMBF), the key Foundation of Education Ministry of China
and National Natural Science Foundation of China (NSFC No. 69578017). 相似文献
472.
针对光通信开关中方向耦合器的功率转换问题,建立了方向耦合器的功率转换模型.并对相位匹配时的光功率转换和相位不匹配时的光功率转换进行了仿真.仿真表明,两个无损耗的相同波导中光功率转换与相位有关. 相似文献
473.
DENG Mao-lin ZHU Wei-qiu 《浙江大学学报(A卷英文版)》2007,8(9):1401-1407
An important functioning mechanism of biological macromolecules is the transition between different conformed states due to thermal fluctuation. In the present paper,a biological macromolecule is modeled as two strands with side chains facing each other,and its stochastic dynamics including the statistics of stationary motion and the statistics of conformational transition is studied by using the stochastic averaging method for quasi Hamiltonian systems. The theoretical results are confirmed with the results from Monte Carlo simulation. 相似文献
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476.
A three-year research project at the University of Southampton (2007–2010) investigated whether monitoring techniques commonly used by engineers to assess the strength and durability of materials could be usefully applied to inform the condition assessment of historic tapestries. To date it has not been possible to obtain an objective picture of the overall condition of a tapestry; the study investigated whether it is possible to identify precursors of structural damage. The two techniques, digital image correlation (DIC) and optical fibre sensors, were used to monitor a representative wool fabric, specially woven tapestry samples, a newly woven tapestry, and historic tapestries, both in the laboratory and in situ in a historic house. This study first sets out to answer the question: can DIC be used to monitor and visualize strain in historic tapestries? It is shown that DIC can be used successfully. Secondly, it discusses the map function, a novel development which allowed the monitoring equipment to be moved, so that it could be used in situ in a historic house. Thirdly, it provides further details of the experimental work using optical fibre sensors to confirm the accuracy of the DIC technique. 相似文献
477.
湖北长江文化产业带的未来发展,应该在新的历史起点上,确立前瞻性战略思路和战略目标,优化带域空间布局,推进产业集聚发展,着力抓好四个关键环节,即培育骨干企业、壮大产业集群、强化品牌运营和完善文化市场体系;着力构建四个重要机制,即资源整合机制、产业联动机制、多元化投融资机制和人才培育机制;着力把握一个战略重点,即强力推进文化科技创新,用高新技术促进文化产业跨越式发展.充分发挥文化产业对经济发展方式转变的助推作用,使之成为促进湖北长江经济带新一轮开放开发的产业先导和重要引擎. 相似文献
478.
中国的改革开放预期了人力资本对社会流动与分层的重要作用。对人力资本、政治资本等回报问题的研究,成为海外中国研究判断市场经济改革现存问题和未来走向的重要依据。1989年,美籍华裔社会学家倪志伟(Victor Nee)率先提出市场转型论(Theory of MarketTransition)进行解释,认为随着改革的推进,将会出现人力资本回报提升、政治资本回报下降的局面。文章鲜明的观点引发了持久争论。为了应对批评,倪志伟先后发表系列文章,对其观点进行持续修正。现在看来,倪志伟的结论当然有固有的缺陷,但对其的批评的确也有误解的成分。同时,包括倪志伟在内的研究者都力求提取简洁的理论模型,追求统一模式,这也为其理论纰漏提供了空间。 相似文献