The integration of large-scale renewable energy introduces frequency instability challenges due to inherent intermittency.While doubly-fed pumped storage units(DFPSUs)offer frequency regulation potential in pumping mo...The integration of large-scale renewable energy introduces frequency instability challenges due to inherent intermittency.While doubly-fed pumped storage units(DFPSUs)offer frequency regulation potential in pumping mode,conventional strategies fail to address hydraulic-mechanical coupling dynamics and operational constraints,limiting their effectiveness.This paper presents an innovative primary frequency control strategy for double-fed pumped storage units(DFPSUs)operating in pumpingmode,integrating an adaptive parameter calculation method.This method is constrained by operational speed and power limits,addressing key performance factors.A dynamic model that incorporates the reversible pump-turbine characteristics is developed to translate frequency deviations into coordinated adjustments in speed and power during pumping operations.The research thoroughly analyzes the influence of control parameters on the frequency response dynamics.Additionally,the paper introduces a deep reinforcement learning(DRL)-based optimization framework,which enables real-time tuning of control parameters in response to changing rotor speed and frequency states.This method strategicallymanages the utilization of kinetic energy while ensuring compliance with operational safety constraints.The effectiveness of the proposed strategy is validated through simulation studies conducted on a four-machine,two-area DFPSU system.These studies demonstrate the strategy’s potential for improving frequency regulation performance under a variety of operating conditions,highlighting its effectiveness in optimizing energy storage and frequency control in power grids.展开更多
Galvanic corrosion of tri-metallic couples is more complicated than that of bi-metallic couples. In this study, the effect of the pH of corrosive media on the galvanic corrosion of 2024 A1 alloy/Q235 mild steel/304 st...Galvanic corrosion of tri-metallic couples is more complicated than that of bi-metallic couples. In this study, the effect of the pH of corrosive media on the galvanic corrosion of 2024 A1 alloy/Q235 mild steel/304 stainless steel tri-metallic couples was investigated using potentiodynamic polarization, scanning electron microscopy, scanning vibrating electrode technique and a multi-channel galvanic corrosion meter. The results show that 2024 always acts as the only anode in 3.5 wt% NaCl at pH 5.56,9.72 and 12.0, while both Q235 and 2024 act as anodes at pH 2.39 in the initial stage and then the role of Q235 changes at longer coupling time, which can be attributed to the effect of pH on the surface film of 2024. It is also found that the galvanic current density of a tri-metallic couple is the superposition of two bi-metallic couples when cathodic reactions are controlled by the diffusion of oxygen, otherwise it is smaller than that of the sum of two bi-metallic couples. The localized corrosion instead of uniform corrosion of anodic metal is accelerated by galvanic corrosion.展开更多
Objective:To elucidate whether DNA aneuploidy was an independent discriminator for carcinoma within oral potentially malignant disorders(OPMDs),and further establish and validate a risk model based on DNA aneuploidy f...Objective:To elucidate whether DNA aneuploidy was an independent discriminator for carcinoma within oral potentially malignant disorders(OPMDs),and further establish and validate a risk model based on DNA aneuploidy for the detection of oral cancer.Methods:A total of 810 consecutive patients with OPMD were prospectively enrolled from March 2013 to December 2018,and divided into a training set(n=608)and a test set(n=202).Brushing and biopsy samples from each patient were processed by DNADNA image cytometry and histopathological examination,respectively.Results:DNA aneuploidy of an outside DNA index≥3.5 in OPMD was an independent marker strongly associated with malignant risk[adjusted odds ratio:13.04;95%confidence interval(CI):5.46-31.14].In the training and test sets,the area under the curve(AUC)was 0.87(95%CI:0.82-0.91)and 0.77(95%CI:0.57-0.97),respectively,for detecting carcinoma in OPMD patients.The independent risk factors of lateral/ventral tongue and non-homogenous type combined with a risk model built with a multivariate logistic regression revealed a more favorable diagnostic efficacy associated with the training set(AUC:0.93;95%CI:0.91-0.96)and test set(AUC:0.94;95%CI:0.90-0.98).The sensitivity and specificity of carcinoma detection within OPMD was improved to 100%and 88.1%,respectively.Conclusions:This large-scale diagnostic study established a risk model based on DNA aneuploidy that consisted of a noninvasive strategy with lateral/ventral tongue and non-homogenous features.The results showed favorable diagnostic efficacy for detecting carcinoma within OPMD,irrespective of the clinical and pathological diagnoses of OPMD.Multicenter validation and longitudinal studies are warranted to evaluate community practices and clinical applications.展开更多
文摘The integration of large-scale renewable energy introduces frequency instability challenges due to inherent intermittency.While doubly-fed pumped storage units(DFPSUs)offer frequency regulation potential in pumping mode,conventional strategies fail to address hydraulic-mechanical coupling dynamics and operational constraints,limiting their effectiveness.This paper presents an innovative primary frequency control strategy for double-fed pumped storage units(DFPSUs)operating in pumpingmode,integrating an adaptive parameter calculation method.This method is constrained by operational speed and power limits,addressing key performance factors.A dynamic model that incorporates the reversible pump-turbine characteristics is developed to translate frequency deviations into coordinated adjustments in speed and power during pumping operations.The research thoroughly analyzes the influence of control parameters on the frequency response dynamics.Additionally,the paper introduces a deep reinforcement learning(DRL)-based optimization framework,which enables real-time tuning of control parameters in response to changing rotor speed and frequency states.This method strategicallymanages the utilization of kinetic energy while ensuring compliance with operational safety constraints.The effectiveness of the proposed strategy is validated through simulation studies conducted on a four-machine,two-area DFPSU system.These studies demonstrate the strategy’s potential for improving frequency regulation performance under a variety of operating conditions,highlighting its effectiveness in optimizing energy storage and frequency control in power grids.
基金supported financially by the National Key Research and Development Program of China (No. 2017YFB0702100)the Natural Science Foundation of Liaoning Province (No. 20170540666)
文摘Galvanic corrosion of tri-metallic couples is more complicated than that of bi-metallic couples. In this study, the effect of the pH of corrosive media on the galvanic corrosion of 2024 A1 alloy/Q235 mild steel/304 stainless steel tri-metallic couples was investigated using potentiodynamic polarization, scanning electron microscopy, scanning vibrating electrode technique and a multi-channel galvanic corrosion meter. The results show that 2024 always acts as the only anode in 3.5 wt% NaCl at pH 5.56,9.72 and 12.0, while both Q235 and 2024 act as anodes at pH 2.39 in the initial stage and then the role of Q235 changes at longer coupling time, which can be attributed to the effect of pH on the surface film of 2024. It is also found that the galvanic current density of a tri-metallic couple is the superposition of two bi-metallic couples when cathodic reactions are controlled by the diffusion of oxygen, otherwise it is smaller than that of the sum of two bi-metallic couples. The localized corrosion instead of uniform corrosion of anodic metal is accelerated by galvanic corrosion.
基金supported by the National Natural Science Foundation of China(Grant No.82074502)the Science and Technology Commission of Shanghai Municipality(Grant No.20Y11903700)+3 种基金the Shanghai Hospital Development Center(Grant No.SHDC2020CR4082)the Shanghai Municipal Health Committee(Grant No.202040457)the Innovative Research Team of High-level Local Universities in Shanghai(Grant No.SSMU-ZDCX20180901)the SHIPM-mu Fund from the Shanghai Institute of Precision Medicine(Grant No.JC201807)。
文摘Objective:To elucidate whether DNA aneuploidy was an independent discriminator for carcinoma within oral potentially malignant disorders(OPMDs),and further establish and validate a risk model based on DNA aneuploidy for the detection of oral cancer.Methods:A total of 810 consecutive patients with OPMD were prospectively enrolled from March 2013 to December 2018,and divided into a training set(n=608)and a test set(n=202).Brushing and biopsy samples from each patient were processed by DNADNA image cytometry and histopathological examination,respectively.Results:DNA aneuploidy of an outside DNA index≥3.5 in OPMD was an independent marker strongly associated with malignant risk[adjusted odds ratio:13.04;95%confidence interval(CI):5.46-31.14].In the training and test sets,the area under the curve(AUC)was 0.87(95%CI:0.82-0.91)and 0.77(95%CI:0.57-0.97),respectively,for detecting carcinoma in OPMD patients.The independent risk factors of lateral/ventral tongue and non-homogenous type combined with a risk model built with a multivariate logistic regression revealed a more favorable diagnostic efficacy associated with the training set(AUC:0.93;95%CI:0.91-0.96)and test set(AUC:0.94;95%CI:0.90-0.98).The sensitivity and specificity of carcinoma detection within OPMD was improved to 100%and 88.1%,respectively.Conclusions:This large-scale diagnostic study established a risk model based on DNA aneuploidy that consisted of a noninvasive strategy with lateral/ventral tongue and non-homogenous features.The results showed favorable diagnostic efficacy for detecting carcinoma within OPMD,irrespective of the clinical and pathological diagnoses of OPMD.Multicenter validation and longitudinal studies are warranted to evaluate community practices and clinical applications.
