为验证收发器硬件损耗对通信系统性能的影响,在考虑收发器硬件损耗的情况下,对智能反射面(intelligent reflecting surface,IRS)辅助的携能通信(simultaneous wireless information and power transfer,SWIPT)系统的鲁棒性传输设计进行...为验证收发器硬件损耗对通信系统性能的影响,在考虑收发器硬件损耗的情况下,对智能反射面(intelligent reflecting surface,IRS)辅助的携能通信(simultaneous wireless information and power transfer,SWIPT)系统的鲁棒性传输设计进行研究.在考虑基站的最大发射功率、能量收集器的最小接收能量和IRS无源波束成形的约束下,将优化目标设为最大化所有信息接收者的加权和速率,并使用块坐标下降(block coordinate descent,BCD)算法将优化问题分解成多个优化子问题,交替优化.对于基站有源波束成形和IRS无源波束成形的优化问题,分别采用拉格朗日对偶方法和最优化最大化(majorization minimization,MM)算法来解决.仿真结果验证了收发器硬件损耗对系统性能的影响,也证实了信息接收端的硬件损耗要比基站发射端的硬件损耗对系统造成的性能下降更明显.展开更多
为进一步提高多输入多输出(MIMO)双向中继系统性能,该文在梯度下降法的基础上,引入用户端功率分配和发射预编码与接收波束成形,结合中继站波束成形矩阵和分配功率相,构成一个完整的联合交替迭代结构(AIS);通过固定变量循环计算,逐个得...为进一步提高多输入多输出(MIMO)双向中继系统性能,该文在梯度下降法的基础上,引入用户端功率分配和发射预编码与接收波束成形,结合中继站波束成形矩阵和分配功率相,构成一个完整的联合交替迭代结构(AIS);通过固定变量循环计算,逐个得到各个变量的最优值。仿真表明,与梯度下降法、迫零和最小均方误差加注水功率分配法相比,该文交替迭代结构方法的速率有所提高,误码性能提高较明显。当误码率等于10-2时,与3种算法中最优的梯度下降法相比,该文方法可获得2.5 d B的信噪比增益。展开更多
全双工系统能实现在同一时隙与同一频率传输数据,相比于半双工系统能大大地提升数据吞吐量和频谱效率。为了进一步提高全双工多输入多输出(Multi-input and multi-output,MIMO)中继系统传输速率,本文基于放大转发(Amplify-and-forward,...全双工系统能实现在同一时隙与同一频率传输数据,相比于半双工系统能大大地提升数据吞吐量和频谱效率。为了进一步提高全双工多输入多输出(Multi-input and multi-output,MIMO)中继系统传输速率,本文基于放大转发(Amplify-and-forward,AF)传输模式,在全双工双向中继系统中引入梯度下降算法,将用户发送端、接收端波束成形与中继端波束成形矩阵相结合设计一种最大化速率的交替迭代算法,并构造出一种最小均方误差(Minimum mean square error,MMSE)迭代算法作为初始条件,在此基础上推导出中继接收端与发射端的波束成形矩阵表达式。仿真结果表明,本文构造的交替迭代算法收敛速度快,而且相比于迫零、最小均方误差以及最大泄信噪比算法,和速率有显著提高。展开更多
移相控制是输入串联输出并联双有源桥(Input Series Output Parallel-Dual Active Bridge,ISOP-DAB)变换器一种常见控制方式,针对传统单移相控制存在动态特性和回流功率问题,提出一种基于扩展移相(Extended Phase Shift,EPS)的混合优化...移相控制是输入串联输出并联双有源桥(Input Series Output Parallel-Dual Active Bridge,ISOP-DAB)变换器一种常见控制方式,针对传统单移相控制存在动态特性和回流功率问题,提出一种基于扩展移相(Extended Phase Shift,EPS)的混合优化控制技术.首先,基于ISOP-DAB的状态空间平均化方程,分析了EPS控制下ISOP-DAB变换器的回流功率和电流应力.其次,通过电压微分方程离散化,建立了DAB变换器控制量预测模型.最后,结合梯度下降算法(Gradient Descent Algorithm,GDA)进行控制优化,并进行了仿真分析.结果表明:基于EPS的ISOP-DAB变换器混合优化控制策略实现了输入电容电压均衡、输出电压稳定及同时优化回流功率的控制目标.展开更多
Aim: Evaluating climbing stairs for prescription and implementation of physical activity regimes. Methods: Healthy females (F, n = 14), and males (M, n = 15) participated. By climbing 100 steps of stairs with 0.173 m ...Aim: Evaluating climbing stairs for prescription and implementation of physical activity regimes. Methods: Healthy females (F, n = 14), and males (M, n = 15) participated. By climbing 100 steps of stairs with 0.173 m height, Heart rate (HR) and oxygen uptake were measured throughout the floors;Blood pressure (BP) was measured at ground and the 5th floors only. Results: Energy increased from 2 to 7.6 was metabolic equivalents (METs = 3.5 ml O<sub>2</sub>/min.kg) at 17.3 m elevation in 2 min. at the 5th floor, and percent Heart Rate Reserve (%HRR) was 66.17% in F and 48.7% in M, proportional to their aerobic efforts. Average climbing efficiency was 15.8 ± 2.3% (n = 29). Aerobic capacity estimated dividing the highest work rate (17.3 Kg.m/2min.Kg × 0.00239 = 0.0207 Kcal/min.Kg), by fractional effort (F = 0.6617, M = 0.487) and fractional efficiency (0.158), at 5 Kcal/L O2 was 0.040 in F and 0.054 L O2/Kg.min in M. Minimum training intensity reached at the 3rd floor by F. In M the highest %HRR reached was 48.7% at the 5th floor, insufficient for training. Conclusions: Stairs used for submaximal evaluation of aerobic capacity and for target intensity prescription. Training, levels climbed, repetitions per day (if 5, 100 Kcal per day, ascending) and number of days/week are adjusted. Full regime requires up to 7.6 METs, a total of 532 and 140 MET.min/week ascending and descending, respectively. Intensities >7.6 MET, climbing rate should be >8.65 m/min. Limiting ascent to 1 (3.5 METs) or 2 (5.5 METs) floors or only descents (2 - 3 METs) may be used for unfit subjects. This method is useful for those with no access to sophisticated facilities.展开更多
文摘为验证收发器硬件损耗对通信系统性能的影响,在考虑收发器硬件损耗的情况下,对智能反射面(intelligent reflecting surface,IRS)辅助的携能通信(simultaneous wireless information and power transfer,SWIPT)系统的鲁棒性传输设计进行研究.在考虑基站的最大发射功率、能量收集器的最小接收能量和IRS无源波束成形的约束下,将优化目标设为最大化所有信息接收者的加权和速率,并使用块坐标下降(block coordinate descent,BCD)算法将优化问题分解成多个优化子问题,交替优化.对于基站有源波束成形和IRS无源波束成形的优化问题,分别采用拉格朗日对偶方法和最优化最大化(majorization minimization,MM)算法来解决.仿真结果验证了收发器硬件损耗对系统性能的影响,也证实了信息接收端的硬件损耗要比基站发射端的硬件损耗对系统造成的性能下降更明显.
文摘为进一步提高多输入多输出(MIMO)双向中继系统性能,该文在梯度下降法的基础上,引入用户端功率分配和发射预编码与接收波束成形,结合中继站波束成形矩阵和分配功率相,构成一个完整的联合交替迭代结构(AIS);通过固定变量循环计算,逐个得到各个变量的最优值。仿真表明,与梯度下降法、迫零和最小均方误差加注水功率分配法相比,该文交替迭代结构方法的速率有所提高,误码性能提高较明显。当误码率等于10-2时,与3种算法中最优的梯度下降法相比,该文方法可获得2.5 d B的信噪比增益。
文摘全双工系统能实现在同一时隙与同一频率传输数据,相比于半双工系统能大大地提升数据吞吐量和频谱效率。为了进一步提高全双工多输入多输出(Multi-input and multi-output,MIMO)中继系统传输速率,本文基于放大转发(Amplify-and-forward,AF)传输模式,在全双工双向中继系统中引入梯度下降算法,将用户发送端、接收端波束成形与中继端波束成形矩阵相结合设计一种最大化速率的交替迭代算法,并构造出一种最小均方误差(Minimum mean square error,MMSE)迭代算法作为初始条件,在此基础上推导出中继接收端与发射端的波束成形矩阵表达式。仿真结果表明,本文构造的交替迭代算法收敛速度快,而且相比于迫零、最小均方误差以及最大泄信噪比算法,和速率有显著提高。
文摘移相控制是输入串联输出并联双有源桥(Input Series Output Parallel-Dual Active Bridge,ISOP-DAB)变换器一种常见控制方式,针对传统单移相控制存在动态特性和回流功率问题,提出一种基于扩展移相(Extended Phase Shift,EPS)的混合优化控制技术.首先,基于ISOP-DAB的状态空间平均化方程,分析了EPS控制下ISOP-DAB变换器的回流功率和电流应力.其次,通过电压微分方程离散化,建立了DAB变换器控制量预测模型.最后,结合梯度下降算法(Gradient Descent Algorithm,GDA)进行控制优化,并进行了仿真分析.结果表明:基于EPS的ISOP-DAB变换器混合优化控制策略实现了输入电容电压均衡、输出电压稳定及同时优化回流功率的控制目标.
文摘Aim: Evaluating climbing stairs for prescription and implementation of physical activity regimes. Methods: Healthy females (F, n = 14), and males (M, n = 15) participated. By climbing 100 steps of stairs with 0.173 m height, Heart rate (HR) and oxygen uptake were measured throughout the floors;Blood pressure (BP) was measured at ground and the 5th floors only. Results: Energy increased from 2 to 7.6 was metabolic equivalents (METs = 3.5 ml O<sub>2</sub>/min.kg) at 17.3 m elevation in 2 min. at the 5th floor, and percent Heart Rate Reserve (%HRR) was 66.17% in F and 48.7% in M, proportional to their aerobic efforts. Average climbing efficiency was 15.8 ± 2.3% (n = 29). Aerobic capacity estimated dividing the highest work rate (17.3 Kg.m/2min.Kg × 0.00239 = 0.0207 Kcal/min.Kg), by fractional effort (F = 0.6617, M = 0.487) and fractional efficiency (0.158), at 5 Kcal/L O2 was 0.040 in F and 0.054 L O2/Kg.min in M. Minimum training intensity reached at the 3rd floor by F. In M the highest %HRR reached was 48.7% at the 5th floor, insufficient for training. Conclusions: Stairs used for submaximal evaluation of aerobic capacity and for target intensity prescription. Training, levels climbed, repetitions per day (if 5, 100 Kcal per day, ascending) and number of days/week are adjusted. Full regime requires up to 7.6 METs, a total of 532 and 140 MET.min/week ascending and descending, respectively. Intensities >7.6 MET, climbing rate should be >8.65 m/min. Limiting ascent to 1 (3.5 METs) or 2 (5.5 METs) floors or only descents (2 - 3 METs) may be used for unfit subjects. This method is useful for those with no access to sophisticated facilities.
