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超快激光脉冲的产生和放大 总被引:1,自引:0,他引:1
超快激光脉冲是实现超高速通信最为重要的部分.近十年来,啁啾脉冲放大技术和宽带增益介质的结合,高功率超快激光脉冲取得了迅猛的发展.在小型实验室桌面激光器就可以产生数太瓦功率的激光.本文介绍了用啁啾脉冲放大技术实现超快脉冲的产生和放大. 相似文献
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王菊霞 《渭南师范学院学报》1998,(2)
本文对非线性介质中的群速色散效应进行了详细分析,指出群速弥散现象是影响超短激光脉冲其脉宽压缩的重要因素之一.另外计算还表明:腔镜的二、三阶色散在中心频率附近较小、两端较大,并且,其色散量的大小与高低镀膜层折射率之比以及镀膜层数等有关,并在此基础上提出了进一步补偿色散的有效途径 相似文献
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介绍了在法拉第效应实验中确定样品介质的色散dn/dλ和波长λ之间关系的两种方法。 相似文献
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赵敏 《河北理科教学研究》2004,(2):58-59
多普勒效应是指因波源与观测者之间有相对运动从而使观测者接收到的频率与波源发出的频率不同的现象.对于机械波,当波源和观测者处于同一直线上时,观测者接收到。 相似文献
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王菊霞 《渭南师范学院学报》1997,(Z2)
本文研究了激光脉冲压缩过程中一个很重要的非线性效应——自相位调制效应.分析了脉冲窄化的机理,同时指出了制约脉冲压缩的其它影响因素,得出了决定脉冲压缩的基本要求. 相似文献
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郭鸿钧 《韩山师范学院学报》1998,19(2):50-53,56
本文根据文[1]得到的具有电荷和磁矩的天体的度规,计算了这类天体的无限红移面和这种天体的引力场中光线的引力偏转,雷达信号的延迟,结果表明,电荷和磁矩的存在,减小了引力质量产生的相应效应,当电荷和磁矩不存在时,所得结果均退化为Schwarzshild天体的情况。 相似文献
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Ji Peiyong Zhu Shitong * Shen Wenda 《上海大学学报(英文版)》1998,2(3):198-203
1IntroductionThegeneralrelativityandsomeothermetrictheoriespredictthatgravitationwilcausethespacetimecurved.Dealingwithlarges... 相似文献
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1Introduction The orthogonal frequency division multiplexing(OFDM)system is becoming a chosen modulationtechnique for wireless communications,which canprovide large data rates with sufficient robustness toradio channel i mpairments.Recently,there have beenmany attempts to further i mprove the OFDM systemperformance.Among them,an adaptive OFDMscheme has attracted much attention[1,2],in whichmodulation mode of each subcarrier is adaptivelychanged with the channel quality.However,such i m-pr… 相似文献
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1 Introduction PlanardevelopmentofacurvedsurfaceisbroadlyusedinCAGDandCAD .Accordingtotheirdevelop ment ,surfacesaredividedintodevelopablesurfacesandnon developablesurfaces .Mostofcurvedsurfacesarenon developable ,butbroadlyusedinengineering ,suchasaircraftwings ,laminaofturbine ,fluidsur face .Howeverthedesignandhandlingofcurvedsur faceareverydifficult.Inordertopredigestthecom plexityofdesign ,planardevelopingisintroduced .Non developablesurfacescannotbedevelopedontoaplanewithoutstretch… 相似文献
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祝和意 《福建工程学院学报》2011,9(3)
温度荷载的作用是造成曲线箱梁桥工程问题的主要原因之一。文章运用曲线梁桥的微分方程,详细分析了混凝土曲线箱梁在均匀温度荷载作用下的效应,推导出了单跨曲线箱梁在径向受到约束时受均匀温度荷载作用产生的支反力及内力计算公式,并利用公式及有限元软件进行实例计算,验证了公式的准确性,得出了曲线箱梁桥在均匀温度荷载作用下,径向反力的大小与桥梁半径的二次方呈反比例关系,与桥梁的刚度、轴线圆心角呈正比例关系,即桥梁的半径越小,桥梁越宽,圆心角越大,桥梁的径向反力越大的结论,为解决曲线箱梁在均匀温度荷载作用下的工程问题提供理论支持。 相似文献
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Recent research challenges in the wireless communication include the usage of diversity and efficient coding to improve data transmission quality and spectral efficiency. Space diversity uses multiple transmitting and/or receiving antennas to create independent fading channels without penalty in bandwidth efficiency. Space-time block coding is an encoding scheme for communication over Rayleigh fading channels using multiple transmitting antennas. Space-time block codes from complex orthogonal designs exist only for two transmitting antennas. This paper generalizes a new complex orthogonal space-time block code for four transmitting antennas, whose decoding complexity is very low. Simulations show that the generalized complex orthogonal space-time block code has low bit error rate, full rate and possibly large diversity. 相似文献
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时空生物学在生命研究中的地位和作用 总被引:1,自引:0,他引:1
刘凯民 《宁波广播电视大学学报》2006,4(2):100-102
本文从“独特而优越的时空条件导致地球生命生存和发展”的事实出发,阐明了时空生物学在生命研究中处于先决地位,并进一步论述了空间生态因子和生物钟在生命研究中的作用。 相似文献
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Multiple antenna wireless systems can provide larger channel capacity and enable spatial diversity to combat fading. In this paper we conduct an investigation into the design of coded space-time system obtained by serially concatenating channel code module and space-time code module with an interleaver in between. As an example, the system is constructed by employing low decoding complexity turbo-SPC (single parity check) code as outer module and linear complex field space-time code as inner module, which achieves full diversity and lossless equivalent channel capacity. Simulation results prove that our designed system performs well and it only loses 0.8 dB from multiple-input multiple-output (MIMO) capacity at BER = 10^-5 in the case of information bit length 6048. Compared with turbo code-based systems, it also has lower error floor. 相似文献