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主要利用支持向量机的机器学习方法开展估算大气光学湍流廓线的研究。通过选取沿海地区实测探空数据,利用温度、压强、相对湿度、风速、风速切变和温度切变实测廓线数据,依据支持向量机估算得到不同日期的大气光学湍流廓线,并与实际测量值进行比较。误差分析结果表明:在2018-05-05和2018-05-10,估算的大气光学湍流廓线与实际测量廓线的均方根误差分别为0.4461和0.3939,相关性分别为70.42%和62.17%。研究证明:根据实测数据训练学习得到的支持向量机模型能够较为准确地估算沿海地区大气光学湍流廓线,虽有一定误差,但大致趋势吻合,验证了支持向量机方法估算大气光学湍流廓线的可行性,从而为利用常规气象探空数据直接估算大气光学湍流廓线,并为建立相关模式的可能性打下基础。 相似文献
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Using differential detection,we perform polarization-multiplexing 160-Gb/s optical non-return-to-zero(NRZ) differential quadrature phase shift keying(DQPSK) signal transmission over 100-km standard single mode fiber at a bit error rate(BER) of less than 10-9.The enabling technology includes clock recovery,fine dispersion compensation,and polarization tracking for de-multiplexing.Furthermore,a hybrid clock recovery scheme is proposed.The scheme is realized with ordinary devices using an optoelectrical modula... 相似文献
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The procedure and method for the transfer of two sets of 14 pairs of wheatgrass (Agropyron interrnedium) chromosomes into common wheat to establish two sets of wheat-wheatgrass alien addition lines are reported. Meanwhile, observations and analyses have been made on the phenotypicaI characters of all the 14 alien addition lines established. It is determined that wheatgrass chromosomes in some of the established addition lines carry the rustresistant genes. In addition, questions concerning the location and distribution of certain agriculturally important genes of wheatgrass chromosomes have been discussed. 相似文献
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Performance improvement of 10-Gb/s XGM wavelength conversion by using polarization control structure
By utilizing the cross polarization modulation effect in semiconductor optical amplifier(SOA), the extinc tion ratio of cross gain modulation(XGM)wavelength conversion was enhanced, the pattern effect was significantly reduced,and the power penalty of wavelength conversion was reduced by 5 dB simultane-ously. Furthermore, by adjusting the settings of polarization controllers, both inverted and non-inverted wavelength conversion can be achieved right in the same wavelength converter. 相似文献
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The principle of error vector magnitude (EVM) against modulator nonlinearity for vector modulation signal (VMS) transmission in radio-over-fiber (RoF) systems is theoretically and experimentally investigated. A highly linear modulation scheme is proposed and demonstrated using a single-drive dual parallel Mach-Zehnder modulator (MZM). This method improves EVM performance and enlarges the linear input dynamic range of the VMS transmission. An index of maximum allowable input power difference (MAIPD) that reflects the difference of upper input power limits between these two schemes is measured. An EVM limitation of 5% MAIPD has 5 dB. Both 16and 64-QAM results indicate that the proposed scheme supports VMS transmission better than the MZM one. 相似文献
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A method of multi-channel receiving for high bit rate heterodyne direct-detection optical orthogonal frequency-division-multiplexing (OOFDM) system is proposed to reduce the sampling rate demand of analog-to-digital converter (ADC). The sampling rate of ADCs can be reduced to 1/N that of the original signal bandwidth in an N-channel receiving system. Aided by a succeeding digital signal processing (DSP) at the receiver, aliasing free signal can be recovered. A back-to-back experimental result is given for a 4-channel system, based on which, a down conversion process for heterodyne can be reduced. The signal rebuilding algorithm is given and analyzed in its complexity and noise tolerance. 相似文献
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The effect of distributed Raman amplification (DRA) on the optical signal to noise ratio (OSNR) of an all optical network (AON) is examined by analyzing two types of node isolated principal (NIP). Based on the parameters used in calculation, it is found that in the first case of NIP, the OSNR of a signal passing through such AON can be improved by about 8 dB compared with no DRA. Whereas in the second case of NIP, the OSNR of the signal can be reduced by 11 dB. This kind of phenomena is analyzed and attributed to the dependence of noise figure of amplification system on the way of the active amplification utilization. 相似文献