In order to accurately forecast the main engine fuel consumption and reduce the Energy Efficiency Operational Indicator(EEOI)of merchant ships in polar ice areas,the energy transfer relationship between ship-machine-p...In order to accurately forecast the main engine fuel consumption and reduce the Energy Efficiency Operational Indicator(EEOI)of merchant ships in polar ice areas,the energy transfer relationship between ship-machine-propeller is studied by analyzing the complex force situation during ship navigation and building a MATLAB/Simulink simulation platform based on multi-environmental resistance,propeller efficiency,main engine power,fuel consumption,fuel consumption rate and EEOI calculation module.Considering the environmental factors of wind,wave and ice,the route is divided into sections,the calculation of main engine power,main engine fuel consumption and EEOI for each section is completed,and the speed design is optimized based on the simulation model for each section.Under the requirements of the voyage plan,the optimization results show that the energy efficiency operation index of the whole route is reduced by 3.114%and the fuel consumption is reduced by 9.17 t.展开更多
ELoran系统作为Loran-C的增强型导航系统,其信号的高精度周期识别对于实现精确定位和授时至关重要。然而,在实际应用中,由于天波干扰和噪声的影响,传统的信号周期识别方法容易出现误差,导致定位精度下降。为了解决这一问题,本文首先采...ELoran系统作为Loran-C的增强型导航系统,其信号的高精度周期识别对于实现精确定位和授时至关重要。然而,在实际应用中,由于天波干扰和噪声的影响,传统的信号周期识别方法容易出现误差,导致定位精度下降。为了解决这一问题,本文首先采用自适应窗宽的频谱相除方法来获取信号的天地波时延和幅值信息。该方法通过调整窗宽,能够在不同信噪比和天地波强度条件下,同时获得较为精确的时延和幅值信息。其次引入粒子群优化算法对快速傅里叶逆变换(Inverse Fast Fourier Transform,IFFT)时延估计结果进行校正。粒子群优化算法通过模拟粒子群体的动态行为,能够有效地搜索到最优的时延估计值,从而显著降低估计误差。解决了传统的频谱相除方法在低信噪比情况下容易受到噪声的影响,导致时延估计误差较大的问题。仿真实验结果表明,该算法在不同信噪比、时延差和幅值比条件下均能准确估计地波时延,误差小于0.5μs,显著优于传统的IFFT和多重信号分类(Multiple Signal Classification,MUSIC)算法。最后利用天波抑制算法降低了天波幅值,在减小了对地波影响的同时让IFFT处于最佳性能区域。仿真结果显示,在信噪比大于0 dB的情况下,该算法的地波时延估计准确率均能保持在90%以上。经过分析,本文算法不仅实现了在强天波、低信噪比条件下天地波分离,同时解决了传统方法的误差问题,为ELoran信号的高精度定位和解码提供了新的思路和方法。展开更多
In this paper, a new partial transmit sequence（PTS）scheme with low computational complexity is proposed for the problems of high computational complexity in the conventional PTS method. By analyzing the relationship...In this paper, a new partial transmit sequence（PTS）scheme with low computational complexity is proposed for the problems of high computational complexity in the conventional PTS method. By analyzing the relationship of candidate sequences in the PTS method under the interleaved partition method, it has been discovered that some candidate sequences generated by phase factor sequences have the same peak average power ratio（PAPR）. Hence, phase factor sequences can be optimized to reduce their searching times. Then, the computational process of generating candidate sequences can be simplified by improving the utilization of data and minimizing the calculations of complex multiplication. The performance analysis shows that, compared with the conventional PTS scheme, the proposed approach significantly decreases the computational complexity and has no loss of PAPR performance.展开更多
Power control is an important technique in WCDMA mobile systems for both increasing system capacity and guaranteeing the required QoS (time delay and wireless link transmission quality) of multimedia services. The opt...Power control is an important technique in WCDMA mobile systems for both increasing system capacity and guaranteeing the required QoS (time delay and wireless link transmission quality) of multimedia services. The optimum power control for narrow band CDMA cellular systems is a problem of single threshold optimization. Because these systems have only one type of traffic and have the same QoS requirement. However, WCDMA mobile system should provide multimedia services and different types of traffic have different QoS requirements. Thus, the power control in WCDMA mobile systems isn't a problem of single threshold optimizing, but turns into the optimizing problem of multi-threshold. We analyze the power control problem in WCDMA cellular mobile systems and propose the optimum transmitter power control algorithm. Three criteria to optimize transmitter power levels of multi-thresholds based on grading the priority orders of multimedia services are proposed. Simulation results show that the proposed algorithms are more effective than conventional algorithms and can provide better performance for WCDMA cellular mobile systems.展开更多
文摘In order to accurately forecast the main engine fuel consumption and reduce the Energy Efficiency Operational Indicator(EEOI)of merchant ships in polar ice areas,the energy transfer relationship between ship-machine-propeller is studied by analyzing the complex force situation during ship navigation and building a MATLAB/Simulink simulation platform based on multi-environmental resistance,propeller efficiency,main engine power,fuel consumption,fuel consumption rate and EEOI calculation module.Considering the environmental factors of wind,wave and ice,the route is divided into sections,the calculation of main engine power,main engine fuel consumption and EEOI for each section is completed,and the speed design is optimized based on the simulation model for each section.Under the requirements of the voyage plan,the optimization results show that the energy efficiency operation index of the whole route is reduced by 3.114%and the fuel consumption is reduced by 9.17 t.
文摘ELoran系统作为Loran-C的增强型导航系统,其信号的高精度周期识别对于实现精确定位和授时至关重要。然而,在实际应用中,由于天波干扰和噪声的影响,传统的信号周期识别方法容易出现误差,导致定位精度下降。为了解决这一问题,本文首先采用自适应窗宽的频谱相除方法来获取信号的天地波时延和幅值信息。该方法通过调整窗宽,能够在不同信噪比和天地波强度条件下,同时获得较为精确的时延和幅值信息。其次引入粒子群优化算法对快速傅里叶逆变换(Inverse Fast Fourier Transform,IFFT)时延估计结果进行校正。粒子群优化算法通过模拟粒子群体的动态行为,能够有效地搜索到最优的时延估计值,从而显著降低估计误差。解决了传统的频谱相除方法在低信噪比情况下容易受到噪声的影响,导致时延估计误差较大的问题。仿真实验结果表明,该算法在不同信噪比、时延差和幅值比条件下均能准确估计地波时延,误差小于0.5μs,显著优于传统的IFFT和多重信号分类(Multiple Signal Classification,MUSIC)算法。最后利用天波抑制算法降低了天波幅值,在减小了对地波影响的同时让IFFT处于最佳性能区域。仿真结果显示,在信噪比大于0 dB的情况下,该算法的地波时延估计准确率均能保持在90%以上。经过分析,本文算法不仅实现了在强天波、低信噪比条件下天地波分离,同时解决了传统方法的误差问题,为ELoran信号的高精度定位和解码提供了新的思路和方法。
基金supported by the National Natural Science Foundation of China(6167309361370152)the Science and Technology Project of Shenyang(F16-205-1-01)
文摘In this paper, a new partial transmit sequence（PTS）scheme with low computational complexity is proposed for the problems of high computational complexity in the conventional PTS method. By analyzing the relationship of candidate sequences in the PTS method under the interleaved partition method, it has been discovered that some candidate sequences generated by phase factor sequences have the same peak average power ratio（PAPR）. Hence, phase factor sequences can be optimized to reduce their searching times. Then, the computational process of generating candidate sequences can be simplified by improving the utilization of data and minimizing the calculations of complex multiplication. The performance analysis shows that, compared with the conventional PTS scheme, the proposed approach significantly decreases the computational complexity and has no loss of PAPR performance.
文摘Power control is an important technique in WCDMA mobile systems for both increasing system capacity and guaranteeing the required QoS (time delay and wireless link transmission quality) of multimedia services. The optimum power control for narrow band CDMA cellular systems is a problem of single threshold optimization. Because these systems have only one type of traffic and have the same QoS requirement. However, WCDMA mobile system should provide multimedia services and different types of traffic have different QoS requirements. Thus, the power control in WCDMA mobile systems isn't a problem of single threshold optimizing, but turns into the optimizing problem of multi-threshold. We analyze the power control problem in WCDMA cellular mobile systems and propose the optimum transmitter power control algorithm. Three criteria to optimize transmitter power levels of multi-thresholds based on grading the priority orders of multimedia services are proposed. Simulation results show that the proposed algorithms are more effective than conventional algorithms and can provide better performance for WCDMA cellular mobile systems.
