Currently,a grid-connected inverter is required to inject a dual-sequence current during asymmetric grid sags,which means both positive and negative sequence phases should be tracked.This paper proposes an open-loop p...Currently,a grid-connected inverter is required to inject a dual-sequence current during asymmetric grid sags,which means both positive and negative sequence phases should be tracked.This paper proposes an open-loop phase synchronization(OLS)method of positive and negative sequences for an asymmetric grid based on the moving average filter(MAF),which does not need to separate the positive and negative sequence fundamental components of grid voltage.As a benefit,there is no double-frequency oscillation in the estimated phases at offnominal frequencies since the positive and negative sequence phases are obtained simultaneously.The proposed method not only has the inherent advantages of OLS,but also further improves the dynamic response since the window length of MAF is only 1/6 of the fundamental period.The effectiveness of the proposed OLS is verified by experimental results.展开更多
With the improved efficacy and accessibility of antiviral agents as well as the concerns about disease progression,there is a hot discussion on whether HBeAg-negative chronic hepatitis B(CHB)patients with normal alani...With the improved efficacy and accessibility of antiviral agents as well as the concerns about disease progression,there is a hot discussion on whether HBeAg-negative chronic hepatitis B(CHB)patients with normal alanine aminotransferase(ALT)and positive HBV DNA should be treated.According to the international guidelines on the stages of the natural history of HBV infection,HBeAgnegative CHB patients with normal ALT and positive HBV DNA can be divided into two groups:one is the well-known“inactive carrier phase”,which is defined as serum HBV DNA<2000 IU/ml and no significant liver inflammation;and the other is the“indeterminate phase”,which is defined as serum HBV DNA≥2000 IU/mL regardless of the pathological changes in liver tissue,or HBV DNA<2000 IU/mL but accompanied by significant pathological changes in the liver.In this minireview,we will expound the disease characteristics,disease progression,and clinical management status of these two groups.Based on the analysis,we propose that HBeAg-negative patients with normal ALT but detectable serum HBV DNA should be treated,regardless of their age,family history of hepatocellular carcinoma(HCC)or the severity of liver necroinflammation.Expanding the indications of antiviral therapy will help improve the survival and quality of life of patients by preventing disease progression,and consequently reduce the risk of HCC development.展开更多
In this paper,we review existing approaches to integrating small gain and small phase analysis for feedback stability of dynamical systems,and give a brief outlook for possible future directions in exploring this topi...In this paper,we review existing approaches to integrating small gain and small phase analysis for feedback stability of dynamical systems,and give a brief outlook for possible future directions in exploring this topic.Small gain analysis has been very successful and popular in control theory since 1960s,while the small phase analysis for multiple-input-multiple-output systems has not been well understood until recently and is now gradually taking shape.Nevertheless,there have been attempts to analyzing feedback stability via the integration of gain and phase information over decades,including the combination of small gain with positive realness as well as that with negative imaginariness.Such combinations can be subsumed into a recently proposed framework for gain-phase integration,which brings in new geometrical methods and also sheds new lights on several future directions.展开更多
文摘Currently,a grid-connected inverter is required to inject a dual-sequence current during asymmetric grid sags,which means both positive and negative sequence phases should be tracked.This paper proposes an open-loop phase synchronization(OLS)method of positive and negative sequences for an asymmetric grid based on the moving average filter(MAF),which does not need to separate the positive and negative sequence fundamental components of grid voltage.As a benefit,there is no double-frequency oscillation in the estimated phases at offnominal frequencies since the positive and negative sequence phases are obtained simultaneously.The proposed method not only has the inherent advantages of OLS,but also further improves the dynamic response since the window length of MAF is only 1/6 of the fundamental period.The effectiveness of the proposed OLS is verified by experimental results.
基金supported by the National Natural Science Fundation of China(Grant No.30972622)the Clinical Research Incubation Project of West China Hospital of Sichuan University(Grant No.2022HXFH013).
文摘With the improved efficacy and accessibility of antiviral agents as well as the concerns about disease progression,there is a hot discussion on whether HBeAg-negative chronic hepatitis B(CHB)patients with normal alanine aminotransferase(ALT)and positive HBV DNA should be treated.According to the international guidelines on the stages of the natural history of HBV infection,HBeAgnegative CHB patients with normal ALT and positive HBV DNA can be divided into two groups:one is the well-known“inactive carrier phase”,which is defined as serum HBV DNA<2000 IU/ml and no significant liver inflammation;and the other is the“indeterminate phase”,which is defined as serum HBV DNA≥2000 IU/mL regardless of the pathological changes in liver tissue,or HBV DNA<2000 IU/mL but accompanied by significant pathological changes in the liver.In this minireview,we will expound the disease characteristics,disease progression,and clinical management status of these two groups.Based on the analysis,we propose that HBeAg-negative patients with normal ALT but detectable serum HBV DNA should be treated,regardless of their age,family history of hepatocellular carcinoma(HCC)or the severity of liver necroinflammation.Expanding the indications of antiviral therapy will help improve the survival and quality of life of patients by preventing disease progression,and consequently reduce the risk of HCC development.
基金supported in part by the Shenzhen Science and Technology Innovation Committee,China(SGDX20201103094600006)the Foshan-HKUST Projects Program(FSUST20-FYTRI12F)+1 种基金the National Natural Science Foundation of China(62103303)the Shanghai Municipal Science and Technology,China Major Project(2021SHZDZX0100).
文摘In this paper,we review existing approaches to integrating small gain and small phase analysis for feedback stability of dynamical systems,and give a brief outlook for possible future directions in exploring this topic.Small gain analysis has been very successful and popular in control theory since 1960s,while the small phase analysis for multiple-input-multiple-output systems has not been well understood until recently and is now gradually taking shape.Nevertheless,there have been attempts to analyzing feedback stability via the integration of gain and phase information over decades,including the combination of small gain with positive realness as well as that with negative imaginariness.Such combinations can be subsumed into a recently proposed framework for gain-phase integration,which brings in new geometrical methods and also sheds new lights on several future directions.
