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Bo Long,Chu Wang,ZiLin Zhu,Xin Lu,LiJun Huang,YuFei Dai,Yong Liao,FuSheng Li 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
In the grid-connected inverter controller system, conventional PI or PR controller decrease their lowfrequency gain and bandwidth to maintain the stability of the system. However, this degrades the disturbance rejection and current tracking capability. To solve this problem, this paper gives an H∞ robust control scheme based on Numerator Denominator Model method, which has the advantages of simplified current controller design procedure, can place the poles of closed-loop system at the desired place. By properly selecting the weight function, the proposed control scheme can not only achieve good robustness in disturbance rejection capability, but also gives a straight forward to design the dynamic performance. Simulation and experimental comparison results between PR and H∞ controller is demonstrated. The results prove that the proposed control scheme shows obviously improvements on the robustness of inverter and meanwhile does not lose advantages on the dynamic performance.
Qiu Shanhu,Yiming Zhu,Bo Xie,Wenji Chen,Duolao Wang,Cai Xue,Sun Zilin,Tongzhi Wu 대한당뇨병학회 2023 Diabetes and Metabolism Journal Vol.47 No.6
Background: Prediabetes leads to declines in physical function in older adults, but the impact of prediabetes progression or regression on physical function is unknown. This study assessed this longitudinal association, with physical function objectivelymeasured by grip strength, walking speed, and standing balance, based on the Health and Retirement Study enrolling United States adults aged >50 years.Methods: Participants with prediabetes were followed-up for 4-year to ascertain prediabetes status alteration (maintained, regressed, or progressed), and another 4-year to assess their impacts on physical function. Weak grip strength was defined as <26 kg for men and <16 kg for women, slow walking speed was as <0.8 m/sec, and poor standing balance was as an uncompleted fulltandem standing testing. Logistic and linear regression analyses were performed.Results: Of the included 1,511 participants with prediabetes, 700 maintained as prediabetes, 306 progressed to diabetes, and 505 regressed to normoglycemia over 4 years. Grip strength and walking speed were declined from baseline during the 4-year followup, regardless of prediabetes status alteration. Compared with prediabetes maintenance, prediabetes progression increased the odds of developing weak grip strength by 89% (95% confidence interval [CI], 0.04 to 2.44) and exhibited larger declines in grip strength by 0.85 kg (95% CI, –1.65 to –0.04). However, prediabetes progression was not related to impairments in walking speed or standing balance. Prediabetes regression also did not affect any measures of physical function.Conclusion: Prediabetes progression accelerates grip strength decline in aging population, while prediabetes regression may not prevent physical function decline due to aging.