电解电容是电源系统中最易失效的元件,其性能参数的退化直接影响系统的可靠性,因此在线监测其等效串联电阻(equivalent series resistance,ESR)和电容值(capacitance,C)的变化十分关键。该文提出了一种新的非侵入式在线监测连续导通模式...电解电容是电源系统中最易失效的元件,其性能参数的退化直接影响系统的可靠性,因此在线监测其等效串联电阻(equivalent series resistance,ESR)和电容值(capacitance,C)的变化十分关键。该文提出了一种新的非侵入式在线监测连续导通模式(continuous conduction mode,CCM)Buck变换器输出电容ESR和C的方法。通过分析输出电压交流分量,结合连续模式下的电容电流表达式,建立ESR和C的实时在线计算模型,设计了电解电容在线监测系统。该方案无需电流传感器,仅采样脉冲宽度调制(pulse-width modulation,PWM)信号和输出电压,不改变Buck变换器的电气结构,就可监测不同工作状态下的ESR和C,完成一台监测系统原理样机并进行实验,实验结果验证了所提方法的有效性。展开更多
当输出电容等效串联电阻(equivalent series resistance,ESR)较小时,传统的固定导通时间(constant on-time,COT)控制的Buck变换器可能工作在不稳定的混沌状态。因此,文章提出COT控制的Buck变换器的仿ESR电压纹波(simulated voltage ripp...当输出电容等效串联电阻(equivalent series resistance,ESR)较小时,传统的固定导通时间(constant on-time,COT)控制的Buck变换器可能工作在不稳定的混沌状态。因此,文章提出COT控制的Buck变换器的仿ESR电压纹波(simulated voltage ripple,SVR)技术,通过构造与ESR电压纹波同步变化的纹波电压,并将此电压叠加到控制环路,实现了低ESR输出电容COT控制Buck变换器的稳定工作。仿真和实验结果验证了理论分析的正确性。展开更多
Objective: To examine and measure the decision-making processes involved in Visual Recognition of Facial Emotional Expressions (VRFEE) and to study the effects of demographic factors on this process. Method: We evalua...Objective: To examine and measure the decision-making processes involved in Visual Recognition of Facial Emotional Expressions (VRFEE) and to study the effects of demographic factors on this process. Method: We evaluated a newly designed software application (M.A.R.I.E.) that permits computerized metric measurement of VRFEE. We administered it to 204 cognitively normal participants ranging in age from 20 to 70 years. Results: We established normative values for the recognition of anger, disgust, joy, fear, surprise and sadness expressed on the faces of three individuals. There was a significant difference in the: 1) measurement (F (8.189) = 3896, p = 0.0001);2) education level (x2(12) = 28.4, p = 0.005);3) face (F(2.195) = 10, p = 0.0001);4)series (F (8.189)=28, p = 0.0001);5) interaction between the identity and recognition of emotions (F (16, 181 =11, p = 0.0001). However, performance did not differ according to: 1) age (F (6.19669) = 1.35, p = 0.2) or 2) level of education (F (1, 1587) = 0.6, p = 0.4). Conclusions: In healthy participants, the VRFEE remains stable throughout the lifespan when cognitive functions remain optimal. Disgust, sadness, fear, and joy seem to be the four most easily recognized facial emotions, while anger and surprise are not easily recognized. Visual recognition of disgust and fear is independent of aging. The characteristics of a face have a significant influence on the ease with which people recognize expressed emotions (idiosyncrasy). Perception and recognition of emotions is categorical, even when the facial images are integrated in a spectrum of morphs reflecting two different emotions on either side.展开更多
模块化多电平换流器(modularmultilevelconverter,MMC)近年来得到了广泛的发展与应用。电容器是MMC中子模块(sub-module,SM)的重要组成部分与关键元件,承担直流支撑与储能工作。为保证MMC系统的安全可靠运行,有必要对子模块电容器状态...模块化多电平换流器(modularmultilevelconverter,MMC)近年来得到了广泛的发展与应用。电容器是MMC中子模块(sub-module,SM)的重要组成部分与关键元件,承担直流支撑与储能工作。为保证MMC系统的安全可靠运行,有必要对子模块电容器状态监测方法展开研究。基于MMC系统运行特性,提出一种在工频周期内对子模块电压进行多相位点采样,并结合系统控制侧开关信号、调制比与交流侧电流电压幅值、相位等信息构建电压电流状态方程,以求解电容值与等效串联电阻(equivalent series resistance,ESR)值等状态特征参量的子模块电容器状态监测方法。随后搭建单相七电平MMC系统仿真平台与半实物仿真平台,对上述方法的可行性与准确性进行验证。仿真结果表明子模块电容器C值监测误差绝对值小于0.03%,ESR值监测误差绝对值小于0.5%。实验结果表明C值监测误差绝对值小于1.5%,ESR值监测误差小于10%,满足子模块电容器状态监测要求。展开更多
文摘当输出电容等效串联电阻(equivalent series resistance,ESR)较小时,传统的固定导通时间(constant on-time,COT)控制的Buck变换器可能工作在不稳定的混沌状态。因此,文章提出COT控制的Buck变换器的仿ESR电压纹波(simulated voltage ripple,SVR)技术,通过构造与ESR电压纹波同步变化的纹波电压,并将此电压叠加到控制环路,实现了低ESR输出电容COT控制Buck变换器的稳定工作。仿真和实验结果验证了理论分析的正确性。
文摘Objective: To examine and measure the decision-making processes involved in Visual Recognition of Facial Emotional Expressions (VRFEE) and to study the effects of demographic factors on this process. Method: We evaluated a newly designed software application (M.A.R.I.E.) that permits computerized metric measurement of VRFEE. We administered it to 204 cognitively normal participants ranging in age from 20 to 70 years. Results: We established normative values for the recognition of anger, disgust, joy, fear, surprise and sadness expressed on the faces of three individuals. There was a significant difference in the: 1) measurement (F (8.189) = 3896, p = 0.0001);2) education level (x2(12) = 28.4, p = 0.005);3) face (F(2.195) = 10, p = 0.0001);4)series (F (8.189)=28, p = 0.0001);5) interaction between the identity and recognition of emotions (F (16, 181 =11, p = 0.0001). However, performance did not differ according to: 1) age (F (6.19669) = 1.35, p = 0.2) or 2) level of education (F (1, 1587) = 0.6, p = 0.4). Conclusions: In healthy participants, the VRFEE remains stable throughout the lifespan when cognitive functions remain optimal. Disgust, sadness, fear, and joy seem to be the four most easily recognized facial emotions, while anger and surprise are not easily recognized. Visual recognition of disgust and fear is independent of aging. The characteristics of a face have a significant influence on the ease with which people recognize expressed emotions (idiosyncrasy). Perception and recognition of emotions is categorical, even when the facial images are integrated in a spectrum of morphs reflecting two different emotions on either side.
文摘模块化多电平换流器(modularmultilevelconverter,MMC)近年来得到了广泛的发展与应用。电容器是MMC中子模块(sub-module,SM)的重要组成部分与关键元件,承担直流支撑与储能工作。为保证MMC系统的安全可靠运行,有必要对子模块电容器状态监测方法展开研究。基于MMC系统运行特性,提出一种在工频周期内对子模块电压进行多相位点采样,并结合系统控制侧开关信号、调制比与交流侧电流电压幅值、相位等信息构建电压电流状态方程,以求解电容值与等效串联电阻(equivalent series resistance,ESR)值等状态特征参量的子模块电容器状态监测方法。随后搭建单相七电平MMC系统仿真平台与半实物仿真平台,对上述方法的可行性与准确性进行验证。仿真结果表明子模块电容器C值监测误差绝对值小于0.03%,ESR值监测误差绝对值小于0.5%。实验结果表明C值监测误差绝对值小于1.5%,ESR值监测误差小于10%,满足子模块电容器状态监测要求。
