为提高零中频接收机中正交(in-phase quadrature,IQ)失配信号校正的收敛速度与鲁棒性,本文将Kalman滤波算法与盲源分离结构结合,提出了一种基于双通道Kalman滤波的校正算法。该算法通过状态空间建模与协方差自适应更新,能够在动态环境...为提高零中频接收机中正交(in-phase quadrature,IQ)失配信号校正的收敛速度与鲁棒性,本文将Kalman滤波算法与盲源分离结构结合,提出了一种基于双通道Kalman滤波的校正算法。该算法通过状态空间建模与协方差自适应更新,能够在动态环境下实现更高效、稳定的参数估计,从而实现对IQ失配信号的有效补偿。将本文算法与最小均方算法(least mean square,LMS)、归一化最小均方算法(normalized least mean square,NLMS)和仿射投影算法(affine projection algorithm,APA)进行对比仿真,结果显示,校正后信号的镜像抑制比(image rejection ratio,IRR)均达到约45 dB,但双通道Kalman滤波算法对应的IRR曲面图更加平滑,同时,16QAM和16PSK调制方式下该算法的误符号率最低,表明本文算法能够有效实现IQ失配校正,具有较好的稳定性。本文算法迭代约50次时,均方误差收敛趋近于0,而LMS、NLMS和APA算法则分别需要迭代约500次、400次和200次才能够收敛,表明该算法具有较好的收敛性。通过参数的敏感性仿真分析,在较大的参数范围内本文算法达到的IRR差别甚微,具有良好的鲁棒性。展开更多
目的探讨Acrysof IQ Restor Toric人工晶状体植入术前后患眼散光、像差及调制传递函数(modulation transfer function,MTF)值变化,评价此种晶状体对术眼视觉质量的影响。方法观察在我院行白内障超声乳化摘出联合IQ Restor Toric IOL植...目的探讨Acrysof IQ Restor Toric人工晶状体植入术前后患眼散光、像差及调制传递函数(modulation transfer function,MTF)值变化,评价此种晶状体对术眼视觉质量的影响。方法观察在我院行白内障超声乳化摘出联合IQ Restor Toric IOL植入的白内障合并角膜散光≥1.0 D的患者8例(10眼),分别于术前、术后1个月、3个月测量裸眼远中近视力、最佳矫正远近视力、等效球镜、残余散光及IOL轴位、总低阶像差和高阶像差、MTF值并问卷调查视觉满意度等。结果术后3个月,裸眼远视力为0.85±0.30,最佳矫正远视力为0.92±0.27,裸眼近视力为0.73±0.22,最佳矫正近视力为0.76±0.20,裸眼中视力为0.62±0.18;等效球镜度数≤±0.5 D者9眼(90%)。术后3个月全眼总散光由术前的(1.50±0.41)D降至(0.28±0.43)D(t=6.124,P=0.000),与术前预计残留散光(0.13±0.09)D相比差异无统计学意义(P>0.05)。术后3个月,IOL轴位偏离(3.20±1.55)°。所有瞳孔直径下,总像差、低阶像差、高阶像差、球差与术前相比均有显著下降(均为P<0.05),术后3 mm瞳孔直径下的总像差、低阶像差和高阶像差(P=0.034、0.044、0.005)以及5 mm瞳孔直径下的总像差、低阶像差、散光像差(P=0.048、0.033、0.046)随时间推移仍有显著降低,余像差随时间变化虽有下降,但差异均无统计学意义(均为P>0.05)。不同瞳孔直径下,MTF值在各个空间频率下与术前相比均有显著提高(均为P<0.05)。结论 Acrysof IQ Restor Toric多焦点散光型人工晶状体能为白内障患者提供良好的全程视力和有效的散光矫正,减少了全眼高阶像差和球差,从而提高了患者的术后视觉质量。展开更多
Objective: To measure IQ and MQ of patients with cerebral vascular diseases (CVD) involving different cerebral lobes and basal ganglia areas. To provide useful data for clinical assessment of brain functions with resp...Objective: To measure IQ and MQ of patients with cerebral vascular diseases (CVD) involving different cerebral lobes and basal ganglia areas. To provide useful data for clinical assessment of brain functions with respect to degree and range of IQ and MQ impairments. Methods: 60 cases of localized CVD were confirmed by clinical diagnosis and CT scan. The patients were evaluated by the WAIS-RC and WMS-RC after convalescence. Results: There were reliable differences between patients and normal controls ( P <0.001), indicating significant intelligence and memory impairments. More pronounced impairments were found in cases with frontal, temporal, occipital and thalamus lesions, but less so with parietal and basal ganglia lesions. Conclusion: The frontal, temporal, occipital lobes and the thalamus play a key and interactive role in the various cognitive processes underlying IQ and MQ.展开更多
文摘为提高零中频接收机中正交(in-phase quadrature,IQ)失配信号校正的收敛速度与鲁棒性,本文将Kalman滤波算法与盲源分离结构结合,提出了一种基于双通道Kalman滤波的校正算法。该算法通过状态空间建模与协方差自适应更新,能够在动态环境下实现更高效、稳定的参数估计,从而实现对IQ失配信号的有效补偿。将本文算法与最小均方算法(least mean square,LMS)、归一化最小均方算法(normalized least mean square,NLMS)和仿射投影算法(affine projection algorithm,APA)进行对比仿真,结果显示,校正后信号的镜像抑制比(image rejection ratio,IRR)均达到约45 dB,但双通道Kalman滤波算法对应的IRR曲面图更加平滑,同时,16QAM和16PSK调制方式下该算法的误符号率最低,表明本文算法能够有效实现IQ失配校正,具有较好的稳定性。本文算法迭代约50次时,均方误差收敛趋近于0,而LMS、NLMS和APA算法则分别需要迭代约500次、400次和200次才能够收敛,表明该算法具有较好的收敛性。通过参数的敏感性仿真分析,在较大的参数范围内本文算法达到的IRR差别甚微,具有良好的鲁棒性。
文摘Objective: To measure IQ and MQ of patients with cerebral vascular diseases (CVD) involving different cerebral lobes and basal ganglia areas. To provide useful data for clinical assessment of brain functions with respect to degree and range of IQ and MQ impairments. Methods: 60 cases of localized CVD were confirmed by clinical diagnosis and CT scan. The patients were evaluated by the WAIS-RC and WMS-RC after convalescence. Results: There were reliable differences between patients and normal controls ( P <0.001), indicating significant intelligence and memory impairments. More pronounced impairments were found in cases with frontal, temporal, occipital and thalamus lesions, but less so with parietal and basal ganglia lesions. Conclusion: The frontal, temporal, occipital lobes and the thalamus play a key and interactive role in the various cognitive processes underlying IQ and MQ.
