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由W.H.Jarvis编写,宣桂鑫等同志翻译,并由许国保同志校订的《国际奥林匹克物理竞赛示范题解》一书,已由上海交通大学出版社出版,国际奥林匹克物理竞赛,一是从二十岁以下尚未取得学位的青年学生中选拔物理“尖子”的国际性竞赛活动.每年轮流由一个国家主办,例如1982年在西德,1983年在罗马尼亚.各竞赛国在国内预赛的基础上选拔五名选手参加.每次竞赛为期十天,包括五小时的理论考试和五小时的实验考试,东道国同时组织旅游活动,还安排运动会与音乐会等等活动,最后一天授奖.许多物理教师和青年学生对国际奥林匹克物理竞赛颇感兴趣.这本书能够帮… 相似文献
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舰艇质心干扰效果的模型及仿真 总被引:9,自引:0,他引:9
建立了质心干扰形成后干扰效果的数学模型,利用计算机仿真技术对干扰过程和效果进行仿真和评估,对实施质心干扰的舰艇机动具有一定的指导意义。 相似文献
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提出一种实现二维光码分多址系统编解码的方法.阐述编解码的原理和电光晶体的基本性质,用电光晶体构造编解码器的关键部件电光偏转器和电光开关,对系统的每个部分进行分析,用具体的地址码进行模拟.结果表明,该方法能有效实现二维光码分多址系统的编解码,并且方法简单、控制灵活、系统升级方便,能够在全光网络通信中发挥重要作用.Abstract: A new encoder-decoder scheme of 2-D OCDMA (Optical Code Division Multiple Access) system is proposed.The principles of encoding-decoding and the characteristics of electro-optic crystals are discussed.The key components,electro-optic deflector and switch,were manufactured by electro-optic crystals and each part of this system was analyzed respectively.A simulation was made with 2-D OOC (optical orthogonal code),and the results showed the effectiveness of this technique in realizing encoder-decoder.This system would play an important role in all-optical telecommunications with its simple scheme,flexible control and convenient upgrade. 相似文献
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Influences of Mg^2+ ion on dopant occupancy and upconversion luminescence of Ho^3+ ion in LiNbO3 crystal
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The effects of a Mg^2+ ion on the dopant occupancy and upconversion luminescence of a Ho^3+ ion in LiNbO3 crystal are reported. The birefringence gradient of the crystal is measured to investigate the optical homogeneity. The X-ray powder diffraction spectrum and the upconversion luminescence are used to investigate defect structure and spectroscopic properties of Mg,Ho:LiNbO3. Under 808-nm excitation, blue, red, and very intense yellow-green bands are observed. Based on the energy levels of Ho^3+ in LiNbO3, and the pump intensity dependence of the observed emission, an excitation scheme is presented. The upconversion emission spectra reveal an enhancement of upconversion intensity when the Mg^2+ ions are introduced into Ho:LiNbO3. The main upconversion mechanism is discussed in this work. 相似文献
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本文详细介绍了半导体激光器驱动电源的工作原理,分别对基于晶体管、场效应管和专用芯片的驱动电源进行分析,对三种驱动电源进行了比较,并设计了一种基于DC/DC转换芯片的可调式激光器驱动电源,该电源输出恒流范围为0-4A,工作性能可靠、稳定,具有较大的应用价值. 相似文献
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