A vector autoregressive model was developed for a sample of container carrier time charter rates. Although the series of time charter rates are themselves found non-stationary, thus precluding the use of many modeling...A vector autoregressive model was developed for a sample of container carrier time charter rates. Although the series of time charter rates are themselves found non-stationary, thus precluding the use of many modeling methodologies, evidence provided by co-integration tests points to the existence of stable long-term relationships between the series. An assessment of the forecasts derived from the model suggests that the spec-ification of these long-term relationships does not improve the accuracy of long-term forecasts. These results are interpreted as a corroboration of the efficient market hypothesis.展开更多
为了最大程度地利用资源和减小电磁干扰,无人机平台的雷达通信一体化设计有着尤为重要的意义。正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)信号具有较高的频谱利用率、较强的抗干扰性能、易于数字化处理等优点,在...为了最大程度地利用资源和减小电磁干扰,无人机平台的雷达通信一体化设计有着尤为重要的意义。正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)信号具有较高的频谱利用率、较强的抗干扰性能、易于数字化处理等优点,在雷达通信一体化系统备受关注。然而,OFDM信号在雷达和通信系统中对多普勒频偏较为敏感,针对多普勒频偏引起的子载波间干扰(Inter-Carrier Interference,ICI)问题,本文设计出一种RS-OFDM雷达通信一体化信号,并提出一种ICI抑制的信号处理算法,其中基于多普勒估计和校正实现OFDM的无ICI处理。仿真结果表明:所提方法在目标成像性能上优于传统方法,且对多普勒频偏具有较强的鲁棒性,而且并无明显增加计算复杂度。展开更多
文摘A vector autoregressive model was developed for a sample of container carrier time charter rates. Although the series of time charter rates are themselves found non-stationary, thus precluding the use of many modeling methodologies, evidence provided by co-integration tests points to the existence of stable long-term relationships between the series. An assessment of the forecasts derived from the model suggests that the spec-ification of these long-term relationships does not improve the accuracy of long-term forecasts. These results are interpreted as a corroboration of the efficient market hypothesis.
文摘为了最大程度地利用资源和减小电磁干扰,无人机平台的雷达通信一体化设计有着尤为重要的意义。正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)信号具有较高的频谱利用率、较强的抗干扰性能、易于数字化处理等优点,在雷达通信一体化系统备受关注。然而,OFDM信号在雷达和通信系统中对多普勒频偏较为敏感,针对多普勒频偏引起的子载波间干扰(Inter-Carrier Interference,ICI)问题,本文设计出一种RS-OFDM雷达通信一体化信号,并提出一种ICI抑制的信号处理算法,其中基于多普勒估计和校正实现OFDM的无ICI处理。仿真结果表明:所提方法在目标成像性能上优于传统方法,且对多普勒频偏具有较强的鲁棒性,而且并无明显增加计算复杂度。
