As an effective approach to achieve the“dual-carbon”goal,the grid-connected capacity of renewable energy increases constantly.Photovoltaics are the most widely used renewable energy sources and have been applied on ...As an effective approach to achieve the“dual-carbon”goal,the grid-connected capacity of renewable energy increases constantly.Photovoltaics are the most widely used renewable energy sources and have been applied on various occasions.However,the inherent randomness,intermittency,and weak support of grid-connected equipment not only cause changes in the original flow characteristics of the grid but also result in complex fault characteristics.Traditional overcurrent and differential protection methods cannot respond accurately due to the effects of unknown renewable energy sources.Therefore,a longitudinal protection method based on virtual measurement of current restraint is proposed in this paper.The positive sequence current data and the network parameters are used to calculate the virtual measurement current which compensates for the output current of photovoltaic(PV).The waveform difference between the virtual measured current and the terminal current for internal and external faults is used to construct the protection method.An improved edit distance algorithm is proposed to measure the similarity between virtual measurement current and terminal measurement current.Finally,the feasibility of the protection method is verified through PSCAD simulation.展开更多
By the investigation of a few historical and cultural villages in Zhejiang Province,some problems during the process of protecting these villages were found,like similar construction pattern,coarse quality of construc...By the investigation of a few historical and cultural villages in Zhejiang Province,some problems during the process of protecting these villages were found,like similar construction pattern,coarse quality of construction,etc. which caused that villages were losing their characters. For this situation,the protection method of historical cultural villages was put forward,which was that to connect excavating character of different village with maintaining spatial fabrics of historical villages,and that different classes of building should have corresponding protection approach. Some advices were proposed for repairing and promoting historic and cultural elements,natural environment,and constructing infrastructure in the village,which will provide a reference for the construction of other historical and cultural villages.展开更多
The influence of various surface coatings, including flame sprayed Cu、 plasma sprayed Cu Ni In、 exploding sprayed WC/Co Ⅰ and plasma sprayed WC/Co Ⅱ, on fretting fatigue resistance for TC11 titanium alloy ...The influence of various surface coatings, including flame sprayed Cu、 plasma sprayed Cu Ni In、 exploding sprayed WC/Co Ⅰ and plasma sprayed WC/Co Ⅱ, on fretting fatigue resistance for TC11 titanium alloy at 20℃ and 500℃ is studied. The results show that the plasma sprayed WC/Co Ⅱ coating has good protection performance and makes the fretting fatigue strength of TC11 titanium alloy raise 40% at both 20℃ and 500℃. The fretting fatigue strength of TC11 alloy with Cu coating is increased about 62% at 20℃, but the protection performance at 500℃ is not so good as that at 20℃.展开更多
This paper firstly made an overview of foreign and domestic theories and methods of landscape architecture heritage protection.It studied the landscape architecture heritage from policies and regulations,investment ma...This paper firstly made an overview of foreign and domestic theories and methods of landscape architecture heritage protection.It studied the landscape architecture heritage from policies and regulations,investment management,talent cultivation,and popular science education.Then,it discussed problems of landscape architecture heritage protection in China:lack of legislation,weak awareness of heritage resources,overdevelopment of heritage resources,and vacancy in management and monitoring of heritage resources.Finally,it came up with recommendations that competent authorities of Chinese government should attach greater importance to heritage management,talent cultivation,and fund input,integrate with advanced management methods of developed countries,and exploring a landscape architecture heritage protection and management mode suitable for national conditions of China at levels of thought,methods,and technology.展开更多
In a poloidal field （PF） converter module, fuse protection is of great importance to ensure the safety of the thyristors. The fuse is pre-selected in a traditional way and then verified by finite element analysis. A...In a poloidal field （PF） converter module, fuse protection is of great importance to ensure the safety of the thyristors. The fuse is pre-selected in a traditional way and then verified by finite element analysis. A 3D physical model is built by ANSYS software to solve the thermal- electric coupled problem of transient process in case of external fault. The result shows that this method is feasible.展开更多
In this study, the Single Factor Test（SFT） was used to optimize the pre-freezing conditions of L. plantarum KLDS1.0391（KLDS1.0391）. Further, the Freeze-Drying Protective Agents（FDPA） of KLDS1.0391 was optimized ...In this study, the Single Factor Test（SFT） was used to optimize the pre-freezing conditions of L. plantarum KLDS1.0391（KLDS1.0391）. Further, the Freeze-Drying Protective Agents（FDPA） of KLDS1.0391 was optimized by Response Surface Methodology（RSM）. The optimum pretreatment conditions were as the follows： initial concentration of KLDS1.0391 was 1011 CFU · m L-1 and KLDS1.0391 was pre-freezed at –80℃ for 8 h to achieve the survival rate of 46.21%. The main components of FDPA were skim milk, sucrose, sodium glutamate and Tween-80. And the influence of four factors on the survival rate of KLDS1.0391 in freeze-drying was in order as the follows： skim milk〉sucrose〉Tween-80〉sodium glutamate. The optimal FDPA composition was skim milk 11.3%, sucrose 9.8%, sodium glutamate 5.1% and Tween-80 0.2%. Under the above conditions, the survival rate of the cells was 82.98%. Comparing the predicted values, the relative error was 0.37% and the difference was not significant, which indicated that the established model could effectively reflect the actual protection of FDPA to KLDS1.0391.展开更多
An accurate determination of lightning protection zone is an important issue in the analysis and design of an appropri-ate lightning protection system. This paper presents a fast and accurate protection zone determina...An accurate determination of lightning protection zone is an important issue in the analysis and design of an appropri-ate lightning protection system. This paper presents a fast and accurate protection zone determination methodology for metallic lightning rod. The methodology is based on Quasi Monte Carlo Integration technique applied to Method of Moments (MoM) solution of Integral Equations. As an example, solution of the integral equation for unknown charge distribution on lightning rod is obtained. The electric field in the region surrounding the rod is then computed and the protection zone plotted accordingly. The effect of the thickness of the rod on the protection zone is also studied.展开更多
In the paper the extended modelling method with serial sands is used in an experimental research on the erosion patterns at the discharge outlet of a beach Hua-Neng power plant. The theoretical basis for the extended ...In the paper the extended modelling method with serial sands is used in an experimental research on the erosion patterns at the discharge outlet of a beach Hua-Neng power plant. The theoretical basis for the extended modelling method with serial sands is systematically presented in the paper and the method has been successfully employed in the sediment experiment of coastal works. According to the Froude Law, the model is designed to be a normal one with movable bed, the geometric scale lambda(L) = lambda(H) = 15, and three scales of sediment grain size are chosen, i.e., lambda(d1) = 0.207; lambda(d2) = 0.393; and lambda(d3) = 0.656. The median particle diameter of sea beach prototype sand d(50p) = 0.059 mm and the dis-changed water flow of the power plant is 21.7 m(3) / s. Three types of natural sea sands have been chosen as the serial modelling sands to extend the simulation of the prototype, thus replacing the conventional test in which artificial lightweight sands are used. As a result, this method can not only reduce the cost significantly, but also it is an advanced technique easy to use. Upon a series of tests, satisfactory results have been obtained.展开更多
基金funded by State Grid Anhui Electric Power Co.,Ltd.Science and Technology Project(52120021N00L)the National Key Research and Development Program of China(2022YFB2400015).
文摘As an effective approach to achieve the“dual-carbon”goal,the grid-connected capacity of renewable energy increases constantly.Photovoltaics are the most widely used renewable energy sources and have been applied on various occasions.However,the inherent randomness,intermittency,and weak support of grid-connected equipment not only cause changes in the original flow characteristics of the grid but also result in complex fault characteristics.Traditional overcurrent and differential protection methods cannot respond accurately due to the effects of unknown renewable energy sources.Therefore,a longitudinal protection method based on virtual measurement of current restraint is proposed in this paper.The positive sequence current data and the network parameters are used to calculate the virtual measurement current which compensates for the output current of photovoltaic(PV).The waveform difference between the virtual measured current and the terminal current for internal and external faults is used to construct the protection method.An improved edit distance algorithm is proposed to measure the similarity between virtual measurement current and terminal measurement current.Finally,the feasibility of the protection method is verified through PSCAD simulation.
基金Sponsored by the Philosophical and Social Science Planning of Zhejiang Provincethe System to Evaluate the Performance of Protection for Historical and Culural Villages in Zhejiang Province (Grant No.14NDJC201YB)the Protection and Renovation of Historical and Cultural Villages in Zhejiang Province Based on the Texture of Villages (Grant No.13NDJC166YB)
文摘By the investigation of a few historical and cultural villages in Zhejiang Province,some problems during the process of protecting these villages were found,like similar construction pattern,coarse quality of construction,etc. which caused that villages were losing their characters. For this situation,the protection method of historical cultural villages was put forward,which was that to connect excavating character of different village with maintaining spatial fabrics of historical villages,and that different classes of building should have corresponding protection approach. Some advices were proposed for repairing and promoting historic and cultural elements,natural environment,and constructing infrastructure in the village,which will provide a reference for the construction of other historical and cultural villages.
文摘The influence of various surface coatings, including flame sprayed Cu、 plasma sprayed Cu Ni In、 exploding sprayed WC/Co Ⅰ and plasma sprayed WC/Co Ⅱ, on fretting fatigue resistance for TC11 titanium alloy at 20℃ and 500℃ is studied. The results show that the plasma sprayed WC/Co Ⅱ coating has good protection performance and makes the fretting fatigue strength of TC11 titanium alloy raise 40% at both 20℃ and 500℃. The fretting fatigue strength of TC11 alloy with Cu coating is increased about 62% at 20℃, but the protection performance at 500℃ is not so good as that at 20℃.
基金Sponsored by Project of National Natural Science Foundation(51178372/E080201)Special Fund for Humanities and Social Science Research Project of Northwest A&F University(2015RWYB38)
文摘This paper firstly made an overview of foreign and domestic theories and methods of landscape architecture heritage protection.It studied the landscape architecture heritage from policies and regulations,investment management,talent cultivation,and popular science education.Then,it discussed problems of landscape architecture heritage protection in China:lack of legislation,weak awareness of heritage resources,overdevelopment of heritage resources,and vacancy in management and monitoring of heritage resources.Finally,it came up with recommendations that competent authorities of Chinese government should attach greater importance to heritage management,talent cultivation,and fund input,integrate with advanced management methods of developed countries,and exploring a landscape architecture heritage protection and management mode suitable for national conditions of China at levels of thought,methods,and technology.
基金supported by the National Magnetic Confinement Fusion Science Program of China(Nos.2010GB108001 and 2013GB113003)
文摘In a poloidal field （PF） converter module, fuse protection is of great importance to ensure the safety of the thyristors. The fuse is pre-selected in a traditional way and then verified by finite element analysis. A 3D physical model is built by ANSYS software to solve the thermal- electric coupled problem of transient process in case of external fault. The result shows that this method is feasible.
基金Supported by the Outstanding Youth Scientists Foundation of Harbin City(2014RFYXJ006)
文摘In this study, the Single Factor Test（SFT） was used to optimize the pre-freezing conditions of L. plantarum KLDS1.0391（KLDS1.0391）. Further, the Freeze-Drying Protective Agents（FDPA） of KLDS1.0391 was optimized by Response Surface Methodology（RSM）. The optimum pretreatment conditions were as the follows： initial concentration of KLDS1.0391 was 1011 CFU · m L-1 and KLDS1.0391 was pre-freezed at –80℃ for 8 h to achieve the survival rate of 46.21%. The main components of FDPA were skim milk, sucrose, sodium glutamate and Tween-80. And the influence of four factors on the survival rate of KLDS1.0391 in freeze-drying was in order as the follows： skim milk〉sucrose〉Tween-80〉sodium glutamate. The optimal FDPA composition was skim milk 11.3%, sucrose 9.8%, sodium glutamate 5.1% and Tween-80 0.2%. Under the above conditions, the survival rate of the cells was 82.98%. Comparing the predicted values, the relative error was 0.37% and the difference was not significant, which indicated that the established model could effectively reflect the actual protection of FDPA to KLDS1.0391.
文摘An accurate determination of lightning protection zone is an important issue in the analysis and design of an appropri-ate lightning protection system. This paper presents a fast and accurate protection zone determination methodology for metallic lightning rod. The methodology is based on Quasi Monte Carlo Integration technique applied to Method of Moments (MoM) solution of Integral Equations. As an example, solution of the integral equation for unknown charge distribution on lightning rod is obtained. The electric field in the region surrounding the rod is then computed and the protection zone plotted accordingly. The effect of the thickness of the rod on the protection zone is also studied.
文摘In the paper the extended modelling method with serial sands is used in an experimental research on the erosion patterns at the discharge outlet of a beach Hua-Neng power plant. The theoretical basis for the extended modelling method with serial sands is systematically presented in the paper and the method has been successfully employed in the sediment experiment of coastal works. According to the Froude Law, the model is designed to be a normal one with movable bed, the geometric scale lambda(L) = lambda(H) = 15, and three scales of sediment grain size are chosen, i.e., lambda(d1) = 0.207; lambda(d2) = 0.393; and lambda(d3) = 0.656. The median particle diameter of sea beach prototype sand d(50p) = 0.059 mm and the dis-changed water flow of the power plant is 21.7 m(3) / s. Three types of natural sea sands have been chosen as the serial modelling sands to extend the simulation of the prototype, thus replacing the conventional test in which artificial lightweight sands are used. As a result, this method can not only reduce the cost significantly, but also it is an advanced technique easy to use. Upon a series of tests, satisfactory results have been obtained.
