Energy storage is an effective measure to deal with internal power fluctuation of micro-grid and ensure stable operation, especially in the micro-grid with high photovoltaic(PV) penetration. Its capacity configuration...Energy storage is an effective measure to deal with internal power fluctuation of micro-grid and ensure stable operation, especially in the micro-grid with high photovoltaic(PV) penetration. Its capacity configuration is related to the steady, safety and economy of micro-grid.In order to improve the absorptive capacity of micro-grid on maximizing the use of distributed PV power in micro-grid, and improve the power quality, an optimal energy storage configuration strategy is proposed, which takes many factors into account, such as the topology of micro-grid, the change of irradiance, the load fluctuation and the cable. The strategy can optimize the energy storage allocation model to minimize the storage power capacity and optimize the node configuration.The key electrical nodes are identified by using the sensitivity coefficient of the voltage, and then the model is optimized to simplify calculation. Finally, an example of the European low-voltage micro-grid and a micro-grid system in the laboratory is used to verify the effectiveness of the proposed method.The results show that the proposed method can optimize the allocation of capacity and the node of the energy storage system.展开更多
The urban heat island(UHI) effect has significant effects on the quality of life and public health. Numerous studies have addressed the relationship between UHI and the increase in urban impervious surface area(ISA), ...The urban heat island(UHI) effect has significant effects on the quality of life and public health. Numerous studies have addressed the relationship between UHI and the increase in urban impervious surface area(ISA), but few of them have considered the impact of the spatial configuration of ISA on UHI. Land surface temperature(LST) may be affected not only by urban land cover, but also by neighboring land cover. The aim of this research was to investigate the effects of the abundance and spatial association of ISAs on LST. Taking Harbin City, China as an example, the impact of ISA spatial association on LST measurements was examined. The abundance of ISAs and the LST measurements were derived from Landsat Thematic Mapper(TM) imagery of 2000 and 2010, and the spatial association patterns of ISAs were calculated using the local Moran’s I index. The impacts of ISA abundance and spatial association on LST were examined using correlation analysis. The results suggested that LST has significant positive associations with both ISA abundance and the Moran’s I index of ISAs, indicating that both the abundance and spatial clustering of ISAs contribute to elevated values of LST. It was also found that LST is positively associated with clustering of high-ISA-percentage areas(i.e.,>50%) and negatively associated with clustering of low-ISA-percentage areas(i.e.,<25%). The results suggest that, in addition to the abundance of ISAs,their spatial association has a significant effect on UHIs.展开更多
The safety of offshore pipeline has drawn a great deal of attention during deepwater installation due to the combined actions of high external pressure, axial tension, and bending moment. Meanwhile, the pipeline confi...The safety of offshore pipeline has drawn a great deal of attention during deepwater installation due to the combined actions of high external pressure, axial tension, and bending moment. Meanwhile, the pipeline configuration has a remarkable effect on the structural behaviour of the tube. The special studies focus on the deepwater S-lay technique in the present paper. The stiffened catenary theory is applied to establish the static equilibrium governing differential equation of a pipe element, and the solution equations of the total pipeline configuration from a lay-barge over a stinger to the seabed are derived, The numerical iteration method for solving pipeline configuration is described in detail, and the corresponding program is developed to conduct the analysis of effects of various parameters such as laying water depth, pipe diameter, thickness of concrete weighted coating layer, stinger length, control strain, and axial tension on pipeline configuration. The results show that the laying water depth, the submerged weight of the pipe, and the axial tension are the critical factors influencing pipeline configuration. In addition, geometrical parameters of the stinger such as length, radius, and shape have an important effect on the pipe-laying capacity of the vessel. The validity of the program is further verified by means of a comparison with results obtained from the commercial finite element software OFFPIPE.展开更多
The Kirchhoff thin elastic rod models are always the important basis to explore the configuration mecha- nism of the flexible structures in both the macroscopic and microscopic scale. As a continuum model of DNA, a th...The Kirchhoff thin elastic rod models are always the important basis to explore the configuration mecha- nism of the flexible structures in both the macroscopic and microscopic scale. As a continuum model of DNA, a thin elastic rod subjected to interfacial interactions is used to investigate the helical equilibrium configuration of DNA in salt solution. In this paper, the Kirchhoff＇s equations in the presence of interracial traction and the free energy density functions of different configurations are studied. The transition formula of the free energy between B-DNA and Z- DNA is obtained, and the results show that the free energy of the transition is mainly determined by the salt concentra- tion, which agrees well with the experimental data.展开更多
The mechanism of three⁃order Rubiks Cube(RC)has the characteristics of recombination and variable degree of freedom,and it is difficult to accurately describe the degree of its freedom.This paper takes RC as...The mechanism of three⁃order Rubiks Cube(RC)has the characteristics of recombination and variable degree of freedom,and it is difficult to accurately describe the degree of its freedom.This paper takes RC as the research object,and the adjacency matrix is constructed based on topology and graph theory in order to describe the variation rule of topological configuration in the single layer rotation of RC.In this paper,the degree of freedom of the RC in any shape can be described by defining the concept of entanglement degree of freedom,establishing a set of adjacency matrix,and determining the degree of freedom of the RC which is attributed to the number of non⁃zero elements in the set of adjacent matrix.The prime number is proposed to describe the rotation of the RC combined with the rotation recognition of RC,which is simple and convenient for computer processing.The research contents in this paper are beneficial to the study of RC from the perspective of mechanism science.Meanwhile,it is of great significance to the study of other complex mechanisms with variable degrees of freedom.展开更多
Due to the defects of current aircraft product configuration technology, such as the gap between product design and cus- tomers＇ requirements, the low configuration efficiency and etc. a customer-oriented product con...Due to the defects of current aircraft product configuration technology, such as the gap between product design and cus- tomers＇ requirements, the low configuration efficiency and etc. a customer-oriented product configuration solution of aircraft was proposed in this paper. Basing on a deep investigation into the market and the structure of the aircraft, this paper proposed a method of dividing and creating the aircraft options, in which we set up optional constraints to meet the demand of configuration and then optimized the constraint algorithm. This work can help to realize the optimum association between the aircraft options and modules. Basing on a research on customer demand, The paper established a customer demand model and a mapping relationship which exists between customer demand and aircraft options, It can also help to make a great contribution to build customer personalized demand of the aircraft configuration orocess and the aircraft confimiration library.展开更多
16 September 2013, Shenzhen--ZTE today unveiled the world＇s first flexible, reconfigurable terabit router that allows customers to build the highest-performance broadband networks. The terabit router supports the de...16 September 2013, Shenzhen--ZTE today unveiled the world＇s first flexible, reconfigurable terabit router that allows customers to build the highest-performance broadband networks. The terabit router supports the deployment of multiple line cards with processing capabilities of 10 Gbps to 1 Tbps. It also supports the deployment of modules that can scale throughput from 200 Gbps to 18 Tbps. For easy installation in a range of environments, the router interfaces are flexible and the component design is loose-coupled. This allows customers to customize networks to their needs and promotes adaptability, consistency, and continuity.展开更多
基金Supported by the National Program of International S&T Cooperation(No.2014DFE60020)Natural Science Foundation of Zhejiang Province(No.LY15E070004)
文摘Energy storage is an effective measure to deal with internal power fluctuation of micro-grid and ensure stable operation, especially in the micro-grid with high photovoltaic(PV) penetration. Its capacity configuration is related to the steady, safety and economy of micro-grid.In order to improve the absorptive capacity of micro-grid on maximizing the use of distributed PV power in micro-grid, and improve the power quality, an optimal energy storage configuration strategy is proposed, which takes many factors into account, such as the topology of micro-grid, the change of irradiance, the load fluctuation and the cable. The strategy can optimize the energy storage allocation model to minimize the storage power capacity and optimize the node configuration.The key electrical nodes are identified by using the sensitivity coefficient of the voltage, and then the model is optimized to simplify calculation. Finally, an example of the European low-voltage micro-grid and a micro-grid system in the laboratory is used to verify the effectiveness of the proposed method.The results show that the proposed method can optimize the allocation of capacity and the node of the energy storage system.
基金Under the auspices of the National Social Science Foundation of China(No.16BJY039)
文摘The urban heat island(UHI) effect has significant effects on the quality of life and public health. Numerous studies have addressed the relationship between UHI and the increase in urban impervious surface area(ISA), but few of them have considered the impact of the spatial configuration of ISA on UHI. Land surface temperature(LST) may be affected not only by urban land cover, but also by neighboring land cover. The aim of this research was to investigate the effects of the abundance and spatial association of ISAs on LST. Taking Harbin City, China as an example, the impact of ISA spatial association on LST measurements was examined. The abundance of ISAs and the LST measurements were derived from Landsat Thematic Mapper(TM) imagery of 2000 and 2010, and the spatial association patterns of ISAs were calculated using the local Moran’s I index. The impacts of ISA abundance and spatial association on LST were examined using correlation analysis. The results suggested that LST has significant positive associations with both ISA abundance and the Moran’s I index of ISAs, indicating that both the abundance and spatial clustering of ISAs contribute to elevated values of LST. It was also found that LST is positively associated with clustering of high-ISA-percentage areas(i.e.,>50%) and negatively associated with clustering of low-ISA-percentage areas(i.e.,<25%). The results suggest that, in addition to the abundance of ISAs,their spatial association has a significant effect on UHIs.
基金supported by the National Natural Science Foundation of China (Grant No. 51009122)the Fundamental Research Funds for the Central Universities (Grant No. 2010QNA4030)the National High Technology Research and Development Program of China (863 Program, Grant No. 2006AA09A105)
文摘The safety of offshore pipeline has drawn a great deal of attention during deepwater installation due to the combined actions of high external pressure, axial tension, and bending moment. Meanwhile, the pipeline configuration has a remarkable effect on the structural behaviour of the tube. The special studies focus on the deepwater S-lay technique in the present paper. The stiffened catenary theory is applied to establish the static equilibrium governing differential equation of a pipe element, and the solution equations of the total pipeline configuration from a lay-barge over a stinger to the seabed are derived, The numerical iteration method for solving pipeline configuration is described in detail, and the corresponding program is developed to conduct the analysis of effects of various parameters such as laying water depth, pipe diameter, thickness of concrete weighted coating layer, stinger length, control strain, and axial tension on pipeline configuration. The results show that the laying water depth, the submerged weight of the pipe, and the axial tension are the critical factors influencing pipeline configuration. In addition, geometrical parameters of the stinger such as length, radius, and shape have an important effect on the pipe-laying capacity of the vessel. The validity of the program is further verified by means of a comparison with results obtained from the commercial finite element software OFFPIPE.
基金Supported by the National Nature Science Foundation of China(No.11372210)the Research Fund for the Doctoral Program of Higher Education of China(No.20120032110010)Tianjin Research Program of Application Foundation and Advanced Technology(No.12JCZDJC28000)
文摘The Kirchhoff thin elastic rod models are always the important basis to explore the configuration mecha- nism of the flexible structures in both the macroscopic and microscopic scale. As a continuum model of DNA, a thin elastic rod subjected to interfacial interactions is used to investigate the helical equilibrium configuration of DNA in salt solution. In this paper, the Kirchhoff＇s equations in the presence of interracial traction and the free energy density functions of different configurations are studied. The transition formula of the free energy between B-DNA and Z- DNA is obtained, and the results show that the free energy of the transition is mainly determined by the salt concentra- tion, which agrees well with the experimental data.
基金the National Natural Science Foundation of China(Grant No.51775473)the Natural Science Foundation of Hebei Province(Grant No.E2018203140).
文摘The mechanism of three⁃order Rubiks Cube(RC)has the characteristics of recombination and variable degree of freedom,and it is difficult to accurately describe the degree of its freedom.This paper takes RC as the research object,and the adjacency matrix is constructed based on topology and graph theory in order to describe the variation rule of topological configuration in the single layer rotation of RC.In this paper,the degree of freedom of the RC in any shape can be described by defining the concept of entanglement degree of freedom,establishing a set of adjacency matrix,and determining the degree of freedom of the RC which is attributed to the number of non⁃zero elements in the set of adjacent matrix.The prime number is proposed to describe the rotation of the RC combined with the rotation recognition of RC,which is simple and convenient for computer processing.The research contents in this paper are beneficial to the study of RC from the perspective of mechanism science.Meanwhile,it is of great significance to the study of other complex mechanisms with variable degrees of freedom.
基金Supported by China's 863 Programs-"Key Technologies of i-Plane for Large Aircraft Development"(No.2009AA043306)Fundamental Research Funds for the Central Universities
文摘Due to the defects of current aircraft product configuration technology, such as the gap between product design and cus- tomers＇ requirements, the low configuration efficiency and etc. a customer-oriented product configuration solution of aircraft was proposed in this paper. Basing on a deep investigation into the market and the structure of the aircraft, this paper proposed a method of dividing and creating the aircraft options, in which we set up optional constraints to meet the demand of configuration and then optimized the constraint algorithm. This work can help to realize the optimum association between the aircraft options and modules. Basing on a research on customer demand, The paper established a customer demand model and a mapping relationship which exists between customer demand and aircraft options, It can also help to make a great contribution to build customer personalized demand of the aircraft configuration orocess and the aircraft confimiration library.
文摘16 September 2013, Shenzhen--ZTE today unveiled the world＇s first flexible, reconfigurable terabit router that allows customers to build the highest-performance broadband networks. The terabit router supports the deployment of multiple line cards with processing capabilities of 10 Gbps to 1 Tbps. It also supports the deployment of modules that can scale throughput from 200 Gbps to 18 Tbps. For easy installation in a range of environments, the router interfaces are flexible and the component design is loose-coupled. This allows customers to customize networks to their needs and promotes adaptability, consistency, and continuity.
