Since the 1990s, the Yellow River stream has been temporarily interrupted for several years, which affects the development of society, the economy and human life, limits the economic potential of the drainage areas, a...Since the 1990s, the Yellow River stream has been temporarily interrupted for several years, which affects the development of society, the economy and human life, limits the economic potential of the drainage areas, and especially causes great harm to regions on the lower reaches. Based on the analysis of the relationship between the development of society and economy and water scarcity, the author thinks it is necessary to optimize and adjust the industrial structure that has extravagantly consumed enormous amounts of water, and to develop ecological agriculture, industry and tourism which are balanced with the ecological environment. Finally, the author puts forward several pieces of advice and countermeasures about how to build the economic systems by which water can be used economically.展开更多
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
Interconnected power systems that link several countries and fully utilize their individual resources in a complementary manner are becoming increasingly important.As these systems enhanee accommodation of renewable e...Interconnected power systems that link several countries and fully utilize their individual resources in a complementary manner are becoming increasingly important.As these systems enhanee accommodation of renewable energy,they also represent a move toward low-carbon and low-emissi on power systems.In this paper,a low-carb on dispatch model is proposed to coo rd i nate the gen erati on output betwee n several coun tries where the carb on emissi on constraint is a priority.An adjustable robust optimization approach is used to find the optimal solution under the worst-case scenario to address the uncertainties associated with renewable energy resources.A specific constraint is that the area control error for each country should be self-balanced.Furthermore,a reformation using participation factors is presented to simplify the proposed robust dispatch model.Simulation results for practical interconnected power systems in northeast Asian countries verify the effectiveness of the proposed model.展开更多
With the rapid development in the service,medical,logistics and other industries,and the increasing demand for unmanned mobile devices,mobile robots with the ability of independent mapping,localization and navigation ...With the rapid development in the service,medical,logistics and other industries,and the increasing demand for unmanned mobile devices,mobile robots with the ability of independent mapping,localization and navigation capabilities have become one of the research hotspots.An accurate map construction is a prerequisite for a mobile robot to achieve autonomous localization and navigation.However,the problems of blurring and missing the borders of obstacles and map boundaries are often faced in the Gmapping algorithm when constructing maps in complex indoor environments.In this pursuit,the present work proposes the development of an improved Gmapping algorithm based on the sparse pose adjustment(SPA)optimizations.The improved Gmapping algorithm is then applied to construct the map of a mobile robot based on single-line Lidar.Experiments show that the improved algorithm could build a more accurate and complete map,reduce the number of particles required for Gmapping,and lower the hardware requirements of the platform,thereby saving and minimizing the computing resources.展开更多
This paper presents a study on the concur- rent topology optimization of a structure and its material microstructure. A modified optimization model is proposed by introducing microstructure orientation angles as a new...This paper presents a study on the concur- rent topology optimization of a structure and its material microstructure. A modified optimization model is proposed by introducing microstructure orientation angles as a new type of design variable. The new model is based on the assumptions that a structure is made of a material with the same microstructure, and the material may have a different orientation within the design domain of the structure. The homogenization theory is applied to link the material and structure scales. An additional post-processing technique is developed for modifying the obtained design to avoid local optima caused by the use of orientation angle variables. Numerical examples are presented to illustrate the viabil- ity and effectiveness of the proposed model. It is found that significant improvement in structural performance can be achieved by optimizing the orientation of microstructures in concurrent topology optimization of structures and materials.展开更多
Photovoltaic(PV)power generation has highly penetrated in distribution networks,providing clean and sustainable energy.However,its uncertain and intermittent power outputs significantly impair network operation,leadin...Photovoltaic(PV)power generation has highly penetrated in distribution networks,providing clean and sustainable energy.However,its uncertain and intermittent power outputs significantly impair network operation,leading to unexpected power loss and voltage fluctuation.To address the uncertainties,this paper proposes a multi-timescale affinely adjustable robust reactive power dispatch(MTAAR-RPD)method to reduce the network power losses as well as alleviate voltage deviations and fluctuations.The MTAAR-RPD aims to coordinate on-load tap changers(OLTCs),capacitor banks(CBs),and PV inverters through a three-stage structure which covers multiple timescales of“hour-minute-second”.The first stage schedules CBs and OLTCs hourly while the second stage dispatches the base reactive power outputs of PV inverter every 15 min.The third stage affinely adjusts the inverter reactive power output based on an optimized Q-P droop controller in real time.The three stages are coordinately optimized by an affinely adjustable robust optimization method.A solution algorithm based on a cutting plane algorithm is developed to solve the optimization problem effectively.The proposed method is verified through theoretical analysis and numerical simulations.展开更多
文摘Since the 1990s, the Yellow River stream has been temporarily interrupted for several years, which affects the development of society, the economy and human life, limits the economic potential of the drainage areas, and especially causes great harm to regions on the lower reaches. Based on the analysis of the relationship between the development of society and economy and water scarcity, the author thinks it is necessary to optimize and adjust the industrial structure that has extravagantly consumed enormous amounts of water, and to develop ecological agriculture, industry and tourism which are balanced with the ecological environment. Finally, the author puts forward several pieces of advice and countermeasures about how to build the economic systems by which water can be used economically.
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the Science and Technology Foundation of Global Energy Interconnection Group Co.,Ltd.(No.524500180012)National Natural Science Foundation of China(No.51977166).
文摘Interconnected power systems that link several countries and fully utilize their individual resources in a complementary manner are becoming increasingly important.As these systems enhanee accommodation of renewable energy,they also represent a move toward low-carbon and low-emissi on power systems.In this paper,a low-carb on dispatch model is proposed to coo rd i nate the gen erati on output betwee n several coun tries where the carb on emissi on constraint is a priority.An adjustable robust optimization approach is used to find the optimal solution under the worst-case scenario to address the uncertainties associated with renewable energy resources.A specific constraint is that the area control error for each country should be self-balanced.Furthermore,a reformation using participation factors is presented to simplify the proposed robust dispatch model.Simulation results for practical interconnected power systems in northeast Asian countries verify the effectiveness of the proposed model.
基金National Key Research and Development of China(No.2019YFB1600700)Sichuan Science and Technology Planning Project(No.2021YFSY0003)。
文摘With the rapid development in the service,medical,logistics and other industries,and the increasing demand for unmanned mobile devices,mobile robots with the ability of independent mapping,localization and navigation capabilities have become one of the research hotspots.An accurate map construction is a prerequisite for a mobile robot to achieve autonomous localization and navigation.However,the problems of blurring and missing the borders of obstacles and map boundaries are often faced in the Gmapping algorithm when constructing maps in complex indoor environments.In this pursuit,the present work proposes the development of an improved Gmapping algorithm based on the sparse pose adjustment(SPA)optimizations.The improved Gmapping algorithm is then applied to construct the map of a mobile robot based on single-line Lidar.Experiments show that the improved algorithm could build a more accurate and complete map,reduce the number of particles required for Gmapping,and lower the hardware requirements of the platform,thereby saving and minimizing the computing resources.
基金supported by the State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, China (Grant GZ1305)
文摘This paper presents a study on the concur- rent topology optimization of a structure and its material microstructure. A modified optimization model is proposed by introducing microstructure orientation angles as a new type of design variable. The new model is based on the assumptions that a structure is made of a material with the same microstructure, and the material may have a different orientation within the design domain of the structure. The homogenization theory is applied to link the material and structure scales. An additional post-processing technique is developed for modifying the obtained design to avoid local optima caused by the use of orientation angle variables. Numerical examples are presented to illustrate the viabil- ity and effectiveness of the proposed model. It is found that significant improvement in structural performance can be achieved by optimizing the orientation of microstructures in concurrent topology optimization of structures and materials.
基金supported in part by the Scientific Research Foundation of Nanjing University of Science and Technology(No.AE89991/255)in part by Jiangsu Provincial Key Laboratory of Smart Grid Technology and Equipment Project,Southeast University+1 种基金in part by the National Natural Science Foundation of China(No.51677025)in part by the Science and Technology Project of State Grid Corporation(No.SGMD0000YXJS1900502)。
文摘Photovoltaic(PV)power generation has highly penetrated in distribution networks,providing clean and sustainable energy.However,its uncertain and intermittent power outputs significantly impair network operation,leading to unexpected power loss and voltage fluctuation.To address the uncertainties,this paper proposes a multi-timescale affinely adjustable robust reactive power dispatch(MTAAR-RPD)method to reduce the network power losses as well as alleviate voltage deviations and fluctuations.The MTAAR-RPD aims to coordinate on-load tap changers(OLTCs),capacitor banks(CBs),and PV inverters through a three-stage structure which covers multiple timescales of“hour-minute-second”.The first stage schedules CBs and OLTCs hourly while the second stage dispatches the base reactive power outputs of PV inverter every 15 min.The third stage affinely adjusts the inverter reactive power output based on an optimized Q-P droop controller in real time.The three stages are coordinately optimized by an affinely adjustable robust optimization method.A solution algorithm based on a cutting plane algorithm is developed to solve the optimization problem effectively.The proposed method is verified through theoretical analysis and numerical simulations.