In this study, molecular weight controllable degradation of algal Laminaria japonica polysaccharides(LPS) was investigated by ultrasound combined with hydrogen peroxide. Three main factors, i.e., ultrasonic power(A), ...In this study, molecular weight controllable degradation of algal Laminaria japonica polysaccharides(LPS) was investigated by ultrasound combined with hydrogen peroxide. Three main factors, i.e., ultrasonic power(A), ultrasonic time(B), and H_2O_2 concentration(C) were chosen for optimizing parameters by employing three-factors, three-levels BBD. The influence of degradation on structure change and antioxidant activities was also investigated. A second-order polynomial equation including molecular weight(Y) of Laminaria japonica polysaccharides and each variable parameter, i.e., ultrasonic power(A), ultrasonic time(B), and H_2O_2 concentration(C), was established: Y=20718.67-4273.13A-4000.38B-1438.75C+2333.25AB+1511.00AC+873.00BC+2838.29A^2 + 2490.79B^2+873.04C^2. The equation regression coefficient value(R^2 = 0.969) indicated that this equation was valid. The value of the adjusted determination coefficient(adjusted R^2 = 0.914) also confirmed that the model was highly significant. The results of selected experimental degradation conditions matched with the predicted value. FT-IR spectra revealed that the structures of LPS before and after degradation were not significantly changed. Antioxidant activities of LPS revealed that low Mws possessed stronger inhibitory than the original polysaccharides. The scavenging effects on superoxide radicals was the highest when IC50 of crude LPS was 4.92 mg mL^(-1) and IC50 of Mw 18.576 KDa was 1.02 mg mL^(-1), which was fourfold higher than initial polysaccharide.展开更多
With photovoltaic(PV)sources becoming more prevalent in the energy generation mix,transitioning grid-connected PV systems from grid-following(GFL)mode to gridforming(GFM)mode becomes essential for offering self-synchr...With photovoltaic(PV)sources becoming more prevalent in the energy generation mix,transitioning grid-connected PV systems from grid-following(GFL)mode to gridforming(GFM)mode becomes essential for offering self-synchronization and active support services.Although numerous GFM methods have been proposed,the potential of DC voltage control malfunction during the provision of the primary and inertia support in a GFM PV system remains insufficiently researched.To fill the gap,some main GFM methods have been integrated into PV systems featuring detailed DC source dynamics.We conduct a comparative analysis of their performance in active support and DC voltage regulation.AC GFM methods such as virtual synchronous machine(VSM)face a significant risk of DC voltage failure in situations like alterations in solar radiation,leading to PV system tripping and jeopardizing local system operation.In the case of DC GFM methods such as matching control(MC),the active support falls short due to the absence of an accurate and dispatchable droop response.To address the issue,a matching synchronous machine(MSM)control method is developed to provide dispatchable active support and enhance the DC voltage dynamics by integrating the MC and VSM control loops.The active support capability of the PV systems with the proposed method is quantified analytically and verified by numerical simulations and field tests.展开更多
Leading cruise control(LCC)in mixed traffic has received wide attention as it can strengthen the capability of connected and automated vehicles in reducing traffic instability and smoothing mixed traffic.However,exist...Leading cruise control(LCC)in mixed traffic has received wide attention as it can strengthen the capability of connected and automated vehicles in reducing traffic instability and smoothing mixed traffic.However,existing predictive LCC cannot directly address head-to-tail string stability(HSS)since velocity fluctuation of human-driven vehicles behind cannot be handled by constraint design in MPC framework.To address this challenge,this paper proposes a control matching MPC approach for LCC in mixed traffic.A head-to-tail string stable feedback controller based on the inverse optimal velocity model is designed to guarantee HSS under bilateral topologies.Then,an MPC controller is proposed and the weighting matrices in the objective function are tuned to match the MPC controller with the head-to-tail string stable feedback controller.Straightforward analysis of HSS and physical/safety constraints satisfaction are neatly combined by the proposed control scheme.The feasibility and closed-loop stability of the MPC controller are analyzed.Finally,simulations verify the effectiveness of the proposed controller.展开更多
Population stratification is a problem in genetic association studies because it is likely to highlight loci that underlie the population structure rather than disease-related loci. At present, principal component ana...Population stratification is a problem in genetic association studies because it is likely to highlight loci that underlie the population structure rather than disease-related loci. At present, principal component analysis （PCA） has been proven to be an effective way to correct for population stratification. However, the conventional PCA algorithm is time-consuming when dealing with large datasets. We developed a Graphic processing unit （GPU）-based PCA software named SHEsisPCA （http：//analysis.bio-x.cn/SHEsisMain.htm） that is highly parallel with a highest speedup greater than 100 compared with its CPU version. A cluster algorithm based on X-means was also implemented as a way to detect population subgroups and to obtain matched cases and controls in order to reduce the genomic inflation and increase the power. A study of both simulated and real datasets showed that SHEsisPCA ran at an extremely high speed while the accuracy was hardly reduced. Therefore, SHEsisPCA can help correct for population stratification much more efficiently than the conventional CPU-based algorithms.展开更多
This paper presents a model matching control （MMC） method based on the sliding mode control （SMC） method for longitudinal acceleration tracking control in a vehicular stop-and-go cruise control system. The nonline...This paper presents a model matching control （MMC） method based on the sliding mode control （SMC） method for longitudinal acceleration tracking control in a vehicular stop-and-go cruise control system. The nonlinearity of the vehicle acceleration response at low speeds was analyzed to develop a transfer function model of the vehicle longitudinal dynamics using the least-mean-square system identification technique. This transfer function was then used to design the MMC controller, including an SMC feedback compensator. The system combines the advantages of the two control methods with robust control and rapid response. Simulations show that the controller enhances the rapid trackability to the vehicle acceleration and improves the system＇s robustness at low speeds compared with conventional PID MMC controllers.展开更多
基金the financial support from the National Natural Science Foundation of China (No.21506220)
文摘In this study, molecular weight controllable degradation of algal Laminaria japonica polysaccharides(LPS) was investigated by ultrasound combined with hydrogen peroxide. Three main factors, i.e., ultrasonic power(A), ultrasonic time(B), and H_2O_2 concentration(C) were chosen for optimizing parameters by employing three-factors, three-levels BBD. The influence of degradation on structure change and antioxidant activities was also investigated. A second-order polynomial equation including molecular weight(Y) of Laminaria japonica polysaccharides and each variable parameter, i.e., ultrasonic power(A), ultrasonic time(B), and H_2O_2 concentration(C), was established: Y=20718.67-4273.13A-4000.38B-1438.75C+2333.25AB+1511.00AC+873.00BC+2838.29A^2 + 2490.79B^2+873.04C^2. The equation regression coefficient value(R^2 = 0.969) indicated that this equation was valid. The value of the adjusted determination coefficient(adjusted R^2 = 0.914) also confirmed that the model was highly significant. The results of selected experimental degradation conditions matched with the predicted value. FT-IR spectra revealed that the structures of LPS before and after degradation were not significantly changed. Antioxidant activities of LPS revealed that low Mws possessed stronger inhibitory than the original polysaccharides. The scavenging effects on superoxide radicals was the highest when IC50 of crude LPS was 4.92 mg mL^(-1) and IC50 of Mw 18.576 KDa was 1.02 mg mL^(-1), which was fourfold higher than initial polysaccharide.
基金supported in part by the National Key R&D Program of China(No.2022YFB2402900)the National Natural Science Foundation of China(No.U2066601)。
文摘With photovoltaic(PV)sources becoming more prevalent in the energy generation mix,transitioning grid-connected PV systems from grid-following(GFL)mode to gridforming(GFM)mode becomes essential for offering self-synchronization and active support services.Although numerous GFM methods have been proposed,the potential of DC voltage control malfunction during the provision of the primary and inertia support in a GFM PV system remains insufficiently researched.To fill the gap,some main GFM methods have been integrated into PV systems featuring detailed DC source dynamics.We conduct a comparative analysis of their performance in active support and DC voltage regulation.AC GFM methods such as virtual synchronous machine(VSM)face a significant risk of DC voltage failure in situations like alterations in solar radiation,leading to PV system tripping and jeopardizing local system operation.In the case of DC GFM methods such as matching control(MC),the active support falls short due to the absence of an accurate and dispatchable droop response.To address the issue,a matching synchronous machine(MSM)control method is developed to provide dispatchable active support and enhance the DC voltage dynamics by integrating the MC and VSM control loops.The active support capability of the PV systems with the proposed method is quantified analytically and verified by numerical simulations and field tests.
基金supported by National Natural Science Foundation of China(52222216,52372411)Young Elite Scientists Sponsorship Program by CAST(2022QNRC001)Hunan Provincial Natural Science Foundation of China(2023JJ10008).
文摘Leading cruise control(LCC)in mixed traffic has received wide attention as it can strengthen the capability of connected and automated vehicles in reducing traffic instability and smoothing mixed traffic.However,existing predictive LCC cannot directly address head-to-tail string stability(HSS)since velocity fluctuation of human-driven vehicles behind cannot be handled by constraint design in MPC framework.To address this challenge,this paper proposes a control matching MPC approach for LCC in mixed traffic.A head-to-tail string stable feedback controller based on the inverse optimal velocity model is designed to guarantee HSS under bilateral topologies.Then,an MPC controller is proposed and the weighting matrices in the objective function are tuned to match the MPC controller with the head-to-tail string stable feedback controller.Straightforward analysis of HSS and physical/safety constraints satisfaction are neatly combined by the proposed control scheme.The feasibility and closed-loop stability of the MPC controller are analyzed.Finally,simulations verify the effectiveness of the proposed controller.
基金supported by the National Key Basic Research Program of China (973 Program) (No. 2015CB559100)the National High Technology Research and Development Program of China (863 Program) (Nos. 2012AA02A515 and2012AA021802)+2 种基金the Natural Science Foundation of China (Nos. 31325014, 81130022, 81272302 and 81421061)the National Program for Support of Top-Notch Young Professionals, the Program of Shanghai Subject Chief Scientist (No. 15XD1502200)"Shu Guang" project supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation (No. 12SG17)
文摘Population stratification is a problem in genetic association studies because it is likely to highlight loci that underlie the population structure rather than disease-related loci. At present, principal component analysis （PCA） has been proven to be an effective way to correct for population stratification. However, the conventional PCA algorithm is time-consuming when dealing with large datasets. We developed a Graphic processing unit （GPU）-based PCA software named SHEsisPCA （http：//analysis.bio-x.cn/SHEsisMain.htm） that is highly parallel with a highest speedup greater than 100 compared with its CPU version. A cluster algorithm based on X-means was also implemented as a way to detect population subgroups and to obtain matched cases and controls in order to reduce the genomic inflation and increase the power. A study of both simulated and real datasets showed that SHEsisPCA ran at an extremely high speed while the accuracy was hardly reduced. Therefore, SHEsisPCA can help correct for population stratification much more efficiently than the conventional CPU-based algorithms.
文摘This paper presents a model matching control （MMC） method based on the sliding mode control （SMC） method for longitudinal acceleration tracking control in a vehicular stop-and-go cruise control system. The nonlinearity of the vehicle acceleration response at low speeds was analyzed to develop a transfer function model of the vehicle longitudinal dynamics using the least-mean-square system identification technique. This transfer function was then used to design the MMC controller, including an SMC feedback compensator. The system combines the advantages of the two control methods with robust control and rapid response. Simulations show that the controller enhances the rapid trackability to the vehicle acceleration and improves the system＇s robustness at low speeds compared with conventional PID MMC controllers.
