为解决传统数字滤波器在有限精度实现时因有限字长(Finite Word Length,FWL)效应导致滤波器性能下降的问题,提出一种L_(2)灵敏度最小化的数字滤波器状态空间实现稀疏化方法.推导前向差分算子数字滤波器结构传输函数及其等效状态空间实现...为解决传统数字滤波器在有限精度实现时因有限字长(Finite Word Length,FWL)效应导致滤波器性能下降的问题,提出一种L_(2)灵敏度最小化的数字滤波器状态空间实现稀疏化方法.推导前向差分算子数字滤波器结构传输函数及其等效状态空间实现,根据可控及可观格莱姆矩阵得到基于相似变换矩阵的L_(2)灵敏度表达式,并进行稀疏化校准,将L_(2)灵敏度最小化问题转换为凸函数求最值问题,求导得到L_(2)灵敏度最小化表达式,代回即得前向差分算子数字滤波器的稀疏化状态空间实现.仿真结果表明,所提方法设计的数字滤波器具有更好的抗FWL效应.展开更多
The damage to the rear surface of fused silica under the action of high power laser is more severe than that incurred by the front surface,which hinders the improvement in the energy of the high power laser device.For...The damage to the rear surface of fused silica under the action of high power laser is more severe than that incurred by the front surface,which hinders the improvement in the energy of the high power laser device.For optical components,the ionization breakdown by laser is a main factor causing damage,particularly with laser plasma shock waves,which can cause large-scale fracture damage in fused silica.In this study,the damage morphology is experimentally investigated,and the characteristics of the damage point are obtained.In the theoretical study,the coupling and transmission of the shock wave in glass are investigated based on the finite element method.Thus,both the magnitude and the orientation of stress are obtained.The damage mechanism of the glass can be explained based on the fracture characteristics of glass under different stresses and also on the variation of the damage zone’s Raman spectrum.In addition,the influence of the glass thickness on the damage morphology is investigated.The results obtained in this study can be used as a reference in understanding the characteristics and mechanism of damage characteristics induced by laser plasma shock waves.展开更多
目的对上海市帕金森病剂末现象问卷研究组(Shanghai Research Alliance of Parkinson’s Disease wearing-off questionnaire,shapd-woq)研究纳入的上海帕金森病(parkinson’s disease,PD)患者按照所属行政区进行分类,以探究不同区域患...目的对上海市帕金森病剂末现象问卷研究组(Shanghai Research Alliance of Parkinson’s Disease wearing-off questionnaire,shapd-woq)研究纳入的上海帕金森病(parkinson’s disease,PD)患者按照所属行政区进行分类,以探究不同区域患者剂末现象(wearing-off phenomenon,WO)发生情况的差异。方法提取shapd-woq研究的数据库中2017年9月—2018年6月于上海市16个行政区的11家三级医院和27家二级医院就诊的PD患者资料,进行区域间差异分析。观察、比较各行政区患者的性别、年龄、发病年龄、病程和Hoehn&Yahr(H&Y)分期,以及抗PD治疗时间、左旋多巴(levodopa,LD)和左旋多巴等效剂量(L-dopa equivalent dosage,LED)日用药剂量、多巴丝肼使用比例。采用中文版剂末现象9项(CWOQ-9)问卷作为患者WO的自评量表,比较各行政区问卷分值和相关症状波动的发生情况;临床医师通过询问病史和查询病例报告表(CRF)以诊断患者是否发生WO;采用Kappa检验分析患者自评为WO阳性率与临床医师诊断患者为WO阳性率的一致性。结果1274例患者被纳入本研究。患者的总体发病年龄为(64.11±10.00)岁,总体H&Y分期为(2.29±0.88)期,两者在各行政区间的差异均有统计学意义(F=2.596、3.599,P=0.001或<0.001)。患者总体LD日用药剂量为(6.52±4.19)mg/(kg·d),总体LED日用药剂量为(8.02±4.74)mg/(kg·d);1274例患者中共有1112例(87.3%)使用多巴丝肼治疗,上述指标在各行政区间的差异均有统计学意义(F=2.724、2.834,χ^(2)=35.769。P<0.001或=0.002)。临床医师诊断患者为WO的总体阳性率为56.4%(719/1274),患者使用CWOQ-9问卷自评为WO的总体阳性率为76.3%(972/1274),两者在各行政区间的差异均有统计学意义(χ^(2)=91.559、95.645,P值均<0.001)。Kappa检验结果显示,患者自评为WO的阳性率与临床医师诊断患者为WO的阳性率的一致性欠佳(κ=0.475)。患者CWOQ-9问卷自评的阳性分值总体为3.00(1.00,4.00)分,各行政区间分值的差异有统计学意义(F=3.660,P<0.001)。各行政区各症状波动的发生率不尽相同,杨浦区发生率最高的为震颤(52.0%),其余各行政区发生率相对最高的为运动缓慢。结论上海市各行政区PD患者的临床特点、用药情况及WO阳性率存在差异,临床医师的WO诊断阳性率与患者自评阳性率的一致性也存在区域间差异,故应有重点地加强部分行政区PD规范化管理的培训与质量控制,使上海市各行政区患者得到均质化的诊疗服务。展开更多
文摘为解决传统数字滤波器在有限精度实现时因有限字长(Finite Word Length,FWL)效应导致滤波器性能下降的问题,提出一种L_(2)灵敏度最小化的数字滤波器状态空间实现稀疏化方法.推导前向差分算子数字滤波器结构传输函数及其等效状态空间实现,根据可控及可观格莱姆矩阵得到基于相似变换矩阵的L_(2)灵敏度表达式,并进行稀疏化校准,将L_(2)灵敏度最小化问题转换为凸函数求最值问题,求导得到L_(2)灵敏度最小化表达式,代回即得前向差分算子数字滤波器的稀疏化状态空间实现.仿真结果表明,所提方法设计的数字滤波器具有更好的抗FWL效应.
基金Project supported by the Key Research and Development Projects of Science and Technology Department of Sichuan Province,China(Grant No.2018FZ0032)the National Natural Science Foundation of China(Grant No.U1730141)
文摘The damage to the rear surface of fused silica under the action of high power laser is more severe than that incurred by the front surface,which hinders the improvement in the energy of the high power laser device.For optical components,the ionization breakdown by laser is a main factor causing damage,particularly with laser plasma shock waves,which can cause large-scale fracture damage in fused silica.In this study,the damage morphology is experimentally investigated,and the characteristics of the damage point are obtained.In the theoretical study,the coupling and transmission of the shock wave in glass are investigated based on the finite element method.Thus,both the magnitude and the orientation of stress are obtained.The damage mechanism of the glass can be explained based on the fracture characteristics of glass under different stresses and also on the variation of the damage zone’s Raman spectrum.In addition,the influence of the glass thickness on the damage morphology is investigated.The results obtained in this study can be used as a reference in understanding the characteristics and mechanism of damage characteristics induced by laser plasma shock waves.
