The plasma wake of reentry vehicles has the advantages of extensive space range and long traceability,which provides new possibilities for the detection and monitoring of reentry vehicles.Based on the Zakharov model,t...The plasma wake of reentry vehicles has the advantages of extensive space range and long traceability,which provides new possibilities for the detection and monitoring of reentry vehicles.Based on the Zakharov model,this work investigates the excitation and power spectrum characteristics of electromagnetic radiation for the plasma wake of a typical reentry vehicle.With the aid of parametric decay instability,the excitation condition of electromagnetic radiation for a typical plasma wake is evaluated first.The power spectrum characteristics of electromagnetic radiation,including the effects of both the flight parameters and incident wave parameters are analyzed in detail.The results show that when the phenomenon of excited electromagnetic radiation occurs,plasma wakes closer to the bottom of the vehicle and with faster speeds require higher incident frequencies and thresholds of the electric field.As the frequency of the incident wave increases,peaks appear in the power spectra of plasma wakes,and their magnitudes increase gradually.The frequency shifts of the secondary peaks are equal,whereas,the peaks of the downshifted spectral lines are generally larger than those of the upshifted spectral lines.The work in this paper provides a new idea and method for the tracking of reentry vehicles,which has potential application value in the field of reentry vehicle detection.展开更多
目的计算上海市奉贤区60岁以上老年人的健康期望寿命(healthy life expectancy,HALE),分析HALE的主要影响因素。方法采用两阶段分层整群抽样的方法抽取1 696位奉贤区60岁以上老人进行问卷调查,采用Sullivan法计算HALE。结果 2015年奉贤...目的计算上海市奉贤区60岁以上老年人的健康期望寿命(healthy life expectancy,HALE),分析HALE的主要影响因素。方法采用两阶段分层整群抽样的方法抽取1 696位奉贤区60岁以上老人进行问卷调查,采用Sullivan法计算HALE。结果 2015年奉贤区男、女性60~岁组老年人HALE分别为19.44岁和20.46岁,HALE损失率分别为15.04%和25.06%。70岁以下年龄组女性HALE均高于男性,差异有统计学意义(P<0.05),但女性HALE损失率均大于同年龄组的男性。影响奉贤区老年人HALE的主要影响因素有性别、年龄、婚姻状况、合理体育锻炼、慢性病史,差异均有统计学意义(P<0.05)。中风等脑血管疾病导致的HALE平均损失率最大。结论为提高老年人的HALE,应提倡健康的生活方式,重点防治中风等脑血管疾病,加强老年人尤其是女性老年人的健康保健服务。展开更多
基金supported by National Natural Science Foundation of China(Nos.62171355,61875156)the 111Project(No.B17035)+1 种基金the Natural Science Basic Research Program of Shaanxi Province(No.2021JM-135)the Stable Support Project of Basic Scientific Research Institutes(Nos.A131901W14,A132001W12)。
文摘The plasma wake of reentry vehicles has the advantages of extensive space range and long traceability,which provides new possibilities for the detection and monitoring of reentry vehicles.Based on the Zakharov model,this work investigates the excitation and power spectrum characteristics of electromagnetic radiation for the plasma wake of a typical reentry vehicle.With the aid of parametric decay instability,the excitation condition of electromagnetic radiation for a typical plasma wake is evaluated first.The power spectrum characteristics of electromagnetic radiation,including the effects of both the flight parameters and incident wave parameters are analyzed in detail.The results show that when the phenomenon of excited electromagnetic radiation occurs,plasma wakes closer to the bottom of the vehicle and with faster speeds require higher incident frequencies and thresholds of the electric field.As the frequency of the incident wave increases,peaks appear in the power spectra of plasma wakes,and their magnitudes increase gradually.The frequency shifts of the secondary peaks are equal,whereas,the peaks of the downshifted spectral lines are generally larger than those of the upshifted spectral lines.The work in this paper provides a new idea and method for the tracking of reentry vehicles,which has potential application value in the field of reentry vehicle detection.
文摘目的计算上海市奉贤区60岁以上老年人的健康期望寿命(healthy life expectancy,HALE),分析HALE的主要影响因素。方法采用两阶段分层整群抽样的方法抽取1 696位奉贤区60岁以上老人进行问卷调查,采用Sullivan法计算HALE。结果 2015年奉贤区男、女性60~岁组老年人HALE分别为19.44岁和20.46岁,HALE损失率分别为15.04%和25.06%。70岁以下年龄组女性HALE均高于男性,差异有统计学意义(P<0.05),但女性HALE损失率均大于同年龄组的男性。影响奉贤区老年人HALE的主要影响因素有性别、年龄、婚姻状况、合理体育锻炼、慢性病史,差异均有统计学意义(P<0.05)。中风等脑血管疾病导致的HALE平均损失率最大。结论为提高老年人的HALE,应提倡健康的生活方式,重点防治中风等脑血管疾病,加强老年人尤其是女性老年人的健康保健服务。
