BACKGROUND The continuous glucose monitoring(CGM)system has become a popular evaluation tool for glucose fluctuation,providing a detailed description of glucose change patterns.We hypothesized that glucose fluctuation...BACKGROUND The continuous glucose monitoring(CGM)system has become a popular evaluation tool for glucose fluctuation,providing a detailed description of glucose change patterns.We hypothesized that glucose fluctuations may contain specific information on differences in glucose change between type 1 diabetes mellitus(T1DM)and type 2 diabetes mellitus(T2DM),despite similarities in change patterns,because of different etiologies.Unlike Fourier transform,continuous wavelet transform(CWT)is able to simultaneously analyze the time and frequency domains of oscillating data.AIM To investigate whether CWT can detect glucose fluctuations in T1DM.METHODS The 60-d and 296-d glucose fluctuation data of patients with T1DM(n=5)and T2DM(n=25)were evaluated respectively.Glucose data obtained every 15 min for 356 d were analyzed.Data were assessed by CWT with Morlet form(n=7)as the mother wavelet.This methodology was employed to search for limited frequency glucose fluctuation in the daily glucose change.The frequency and enclosed area(0.02625 scalogram value)of 18 emerged signals were compared.The specificity for T1DM was evaluated through multiple regression analysis using items that demonstrated significant differences between them as explanatory variables.RESULTS The high frequency at midnight(median:75 Hz,cycle time:19 min)and middle frequency at noon(median:45.5 Hz,cycle time:32 min)were higher in T1DM vs T2DM(median:73 and 44 Hz;P=0.006 and 0.005,respectively).The area of the>100 Hz zone at midnight to forenoon was more frequent and larger in T1DM vs T2DM.In a day,the lower frequency zone(15-35 Hz)was more frequent and the area was larger in T2DM than in T1DM.The threedimensional scatter diagrams,which consist of the time of day,frequency,and area of each signal after CWT,revealed that high frequency signals belonging to T1DM at midnight had a loose distribution of wave cycles that were 17-24 min.Multivariate analysis revealed that the high frequency signal at midnight could characterize T1DM(odds ratio:1.33,95%confidence i展开更多
A buck DC/DC switching regulator is implemented by automatically altering the modulation mode according to the load current that ranges from 0.01 to 3A. The pseudo-PFM mode is applied when duty cycle is less than 20% ...A buck DC/DC switching regulator is implemented by automatically altering the modulation mode according to the load current that ranges from 0.01 to 3A. The pseudo-PFM mode is applied when duty cycle is less than 20% ,and the PWM mode is selected in a range of duty cycle from 20% to 100%. The average conversion efficiency of the regulator is about 90% when the output current varies. The proposed dual-mode-control die is implemented in a 0.5μm DPDM CMOS mixed-signal process and a power p-MOSFET is used in the chip by hybrid integration.展开更多
北斗B1频点信号采用二次编码结构,而二次编码使用的NH(Neumann-Hoffman)码会发生比特跳变,导致接收机捕获性能降低,对此,提出一种基于伪码与多普勒频率分离的北斗信号捕获算法.该算法将接收信号分为两路,利用延迟差分运算和测距码的双...北斗B1频点信号采用二次编码结构,而二次编码使用的NH(Neumann-Hoffman)码会发生比特跳变,导致接收机捕获性能降低,对此,提出一种基于伪码与多普勒频率分离的北斗信号捕获算法.该算法将接收信号分为两路,利用延迟差分运算和测距码的双极性分别对两路信号进行处理,消除了NH码比特跳变带来的影响.在此基础上使用匹配滤波器捕获码相位,使用快速傅里叶变换搜索多普勒频移,实现了码相位和多普勒频移的同时捕获.仿真结果表明,提出的算法成功捕获到了NH码跳变的信号,且在相同虚警率下灵敏度相比部分匹配滤波和快速傅里叶变换算法约有1. 03 d B的提升.展开更多
A new time-frequency representation called Dopplerlet transform, which uses the dilated, translated and modulated windowed Doppler signals as its basis functions, is proposed, and the Fourier transform, short-time Fou...A new time-frequency representation called Dopplerlet transform, which uses the dilated, translated and modulated windowed Doppler signals as its basis functions, is proposed, and the Fourier transform, short-time Fourier transform (including Gabor transform), wavelet transform, and chirplet transform are formulated in one framework of Dopplerlet transform accordingly.It is proved that the matching pursuits based on Dopplerlet basis functions are convergent, and that the energy of residual signals yielded in the decomposition process decays exponentially. Simulation results show that the matching pursuits with Dopplerlet basis functions can characterize compactly a nonstationary signal.展开更多
利用雷达目标在空间的稀疏特性,研究了一种基于压缩感知的伪随机频率步进雷达(compressive sensing based pseudo-random step frequency radar,CS-PRSFR)。首先,在分析CS-PRSFR目标回波的基础上,建立了目标参数提取模型;然后,针对在噪...利用雷达目标在空间的稀疏特性,研究了一种基于压缩感知的伪随机频率步进雷达(compressive sensing based pseudo-random step frequency radar,CS-PRSFR)。首先,在分析CS-PRSFR目标回波的基础上,建立了目标参数提取模型;然后,针对在噪声统计特性未知时,传统稀疏信号重构算法无法适用的问题,提出一种基于交叉验证的稳健SL0(robust SL0based on cross validation,CV-RSL0)目标参数提取算法。CS-PRSFR由于其感知矩阵较强的非相关性,可获得更高的距离-速度联合分辨性能;该算法无需已知噪声统计特性,随着信噪比的提高,其目标参数提取性能能够快速逼近最佳估计的下限。仿真结果表明该方法的正确性和有效性。展开更多
文摘BACKGROUND The continuous glucose monitoring(CGM)system has become a popular evaluation tool for glucose fluctuation,providing a detailed description of glucose change patterns.We hypothesized that glucose fluctuations may contain specific information on differences in glucose change between type 1 diabetes mellitus(T1DM)and type 2 diabetes mellitus(T2DM),despite similarities in change patterns,because of different etiologies.Unlike Fourier transform,continuous wavelet transform(CWT)is able to simultaneously analyze the time and frequency domains of oscillating data.AIM To investigate whether CWT can detect glucose fluctuations in T1DM.METHODS The 60-d and 296-d glucose fluctuation data of patients with T1DM(n=5)and T2DM(n=25)were evaluated respectively.Glucose data obtained every 15 min for 356 d were analyzed.Data were assessed by CWT with Morlet form(n=7)as the mother wavelet.This methodology was employed to search for limited frequency glucose fluctuation in the daily glucose change.The frequency and enclosed area(0.02625 scalogram value)of 18 emerged signals were compared.The specificity for T1DM was evaluated through multiple regression analysis using items that demonstrated significant differences between them as explanatory variables.RESULTS The high frequency at midnight(median:75 Hz,cycle time:19 min)and middle frequency at noon(median:45.5 Hz,cycle time:32 min)were higher in T1DM vs T2DM(median:73 and 44 Hz;P=0.006 and 0.005,respectively).The area of the>100 Hz zone at midnight to forenoon was more frequent and larger in T1DM vs T2DM.In a day,the lower frequency zone(15-35 Hz)was more frequent and the area was larger in T2DM than in T1DM.The threedimensional scatter diagrams,which consist of the time of day,frequency,and area of each signal after CWT,revealed that high frequency signals belonging to T1DM at midnight had a loose distribution of wave cycles that were 17-24 min.Multivariate analysis revealed that the high frequency signal at midnight could characterize T1DM(odds ratio:1.33,95%confidence i
文摘A buck DC/DC switching regulator is implemented by automatically altering the modulation mode according to the load current that ranges from 0.01 to 3A. The pseudo-PFM mode is applied when duty cycle is less than 20% ,and the PWM mode is selected in a range of duty cycle from 20% to 100%. The average conversion efficiency of the regulator is about 90% when the output current varies. The proposed dual-mode-control die is implemented in a 0.5μm DPDM CMOS mixed-signal process and a power p-MOSFET is used in the chip by hybrid integration.
文摘北斗B1频点信号采用二次编码结构,而二次编码使用的NH(Neumann-Hoffman)码会发生比特跳变,导致接收机捕获性能降低,对此,提出一种基于伪码与多普勒频率分离的北斗信号捕获算法.该算法将接收信号分为两路,利用延迟差分运算和测距码的双极性分别对两路信号进行处理,消除了NH码比特跳变带来的影响.在此基础上使用匹配滤波器捕获码相位,使用快速傅里叶变换搜索多普勒频移,实现了码相位和多普勒频移的同时捕获.仿真结果表明,提出的算法成功捕获到了NH码跳变的信号,且在相同虚警率下灵敏度相比部分匹配滤波和快速傅里叶变换算法约有1. 03 d B的提升.
基金Supported by the National Natural Science Fundation of China(Grant No.69775009)
文摘A new time-frequency representation called Dopplerlet transform, which uses the dilated, translated and modulated windowed Doppler signals as its basis functions, is proposed, and the Fourier transform, short-time Fourier transform (including Gabor transform), wavelet transform, and chirplet transform are formulated in one framework of Dopplerlet transform accordingly.It is proved that the matching pursuits based on Dopplerlet basis functions are convergent, and that the energy of residual signals yielded in the decomposition process decays exponentially. Simulation results show that the matching pursuits with Dopplerlet basis functions can characterize compactly a nonstationary signal.
文摘利用雷达目标在空间的稀疏特性,研究了一种基于压缩感知的伪随机频率步进雷达(compressive sensing based pseudo-random step frequency radar,CS-PRSFR)。首先,在分析CS-PRSFR目标回波的基础上,建立了目标参数提取模型;然后,针对在噪声统计特性未知时,传统稀疏信号重构算法无法适用的问题,提出一种基于交叉验证的稳健SL0(robust SL0based on cross validation,CV-RSL0)目标参数提取算法。CS-PRSFR由于其感知矩阵较强的非相关性,可获得更高的距离-速度联合分辨性能;该算法无需已知噪声统计特性,随着信噪比的提高,其目标参数提取性能能够快速逼近最佳估计的下限。仿真结果表明该方法的正确性和有效性。
