Completing the principal engineering components of a pumped storage power station spans between 50 and 60 months,from the inception of construction to the commencement of power generation by the first unit.The filling...Completing the principal engineering components of a pumped storage power station spans between 50 and 60 months,from the inception of construction to the commencement of power generation by the first unit.The filling of the penstock with water represents a critical phase preceding the production of electricity by the first unit.During this interval,the construction of the diversion shaft presents multiple challenges,including intricate construction procedures,considerable construction difficulty,elevated safety risks,and quality control issues.To address this issue,this study uses CFD software to analyze the flow field,pressure gradient,and head loss of shaft curved section with different curvature radius,and examines several key technologies by drawing on the practice of diversion shaft construction at the Meizhou pumped storage power station.These technologies include optimizing the curvature radius of the curved section of diversion shaft,reverse-well excavation for the shaft,and sliding-up for the lining concrete.It is found that as the curvature radius of shaft curved section reduces from 4 to 2 times the shaft diameter,the hydraulic characteristic index does not change much,and the increase of head loss accounts for about 0.18%of the total head loss of the water conveyance system.The result show that optimizing the curvature radius from 4 times to 2 times the shaft diameter is feasible and reasonable,and several improved technical measures have been proposed,such as stabilizing drill rods,mechanical scraper systems,and control technology of the relationship between concrete setting time and formwork sliding.Their implementation effectively mitigates difficulties and safety risks during shaft construction,expedites the project schedule,enhances engineering quality,and creates a 41-month timeline for the principal engineering schedule for the first power unit generation in China.展开更多
Coal occupies a dominant position in China＇s national economy and is an essential energy source for future industrial development. To inform the efficient and sustainable development of the coal industry, this paper ...Coal occupies a dominant position in China＇s national economy and is an essential energy source for future industrial development. To inform the efficient and sustainable development of the coal industry, this paper analyzes the sources of strategic risk for coal science and technology enterprises using 3 first-class indicators, 10 second-level indicators, and 37 observation points established through the existing research literature and experience. Moreover, in accordance to the obtained initial index data, the selected indicators have been tested and screened using reliability and membership degree analyses to remove redundant variables, avoid juxtaposition of risk factors at different levels, and reduce the influ- ence of some tiny risk factors for enterprise strategic risk. Then, factor analysis of external environment factor sub-scale was carried out. Factors are extracted according to a standard characteristic value greater than 1. Variables with high coefficients are classified into one factor category; and finally, 3 first-class indicators. 8 second-level indicators, and 37 observation noints are reconstructed.展开更多
The recent research progress of structure- and size-controlled micro/nano-energetic materials is reviewed, which properties are fundamentally different from those of their corresponding bulk materials. The development...The recent research progress of structure- and size-controlled micro/nano-energetic materials is reviewed, which properties are fundamentally different from those of their corresponding bulk materials. The development of the construction strategies for achieving zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) micro/nanostructures from energetic molecules is introduced. Also, an overview of the unique properties induced by micro/nanostructures and size effects is provided. Special emphasis is focused on the size-dependent properties that are different from those of the conventional micro-sized energetic materials, such as thermal decomposition, sensitivity, combustion and detonation, and compaction behaviors. A conclusion and our view of the future development of micro/nano-energetic materials and devices are given.展开更多
With high rock slope in shiplock area, thin reinforced concrete lining walls are constructed for the shiplock system. The construction technology involves much complicated structures in formwork, frequent interference...With high rock slope in shiplock area, thin reinforced concrete lining walls are constructed for the shiplock system. The construction technology involves much complicated structures in formwork, frequent interference due to crossover working procedures, tight time schedule, high quality of reinforced concrete and showcase appearance requirements, hidden troubles affecting construction safety. With above-mentioned factors in consideration, a single-side-separated sliding formwork technology advanced from past sliding formwork experiences has been developed and applied successfully. This new technology is beneficial in quick and safe operation, capable to assure best quality and appearance of shiplock concrete works, and has filled up the gap in terms of construction sliding formwork in our country.展开更多
文摘Completing the principal engineering components of a pumped storage power station spans between 50 and 60 months,from the inception of construction to the commencement of power generation by the first unit.The filling of the penstock with water represents a critical phase preceding the production of electricity by the first unit.During this interval,the construction of the diversion shaft presents multiple challenges,including intricate construction procedures,considerable construction difficulty,elevated safety risks,and quality control issues.To address this issue,this study uses CFD software to analyze the flow field,pressure gradient,and head loss of shaft curved section with different curvature radius,and examines several key technologies by drawing on the practice of diversion shaft construction at the Meizhou pumped storage power station.These technologies include optimizing the curvature radius of the curved section of diversion shaft,reverse-well excavation for the shaft,and sliding-up for the lining concrete.It is found that as the curvature radius of shaft curved section reduces from 4 to 2 times the shaft diameter,the hydraulic characteristic index does not change much,and the increase of head loss accounts for about 0.18%of the total head loss of the water conveyance system.The result show that optimizing the curvature radius from 4 times to 2 times the shaft diameter is feasible and reasonable,and several improved technical measures have been proposed,such as stabilizing drill rods,mechanical scraper systems,and control technology of the relationship between concrete setting time and formwork sliding.Their implementation effectively mitigates difficulties and safety risks during shaft construction,expedites the project schedule,enhances engineering quality,and creates a 41-month timeline for the principal engineering schedule for the first power unit generation in China.
文摘Coal occupies a dominant position in China＇s national economy and is an essential energy source for future industrial development. To inform the efficient and sustainable development of the coal industry, this paper analyzes the sources of strategic risk for coal science and technology enterprises using 3 first-class indicators, 10 second-level indicators, and 37 observation points established through the existing research literature and experience. Moreover, in accordance to the obtained initial index data, the selected indicators have been tested and screened using reliability and membership degree analyses to remove redundant variables, avoid juxtaposition of risk factors at different levels, and reduce the influ- ence of some tiny risk factors for enterprise strategic risk. Then, factor analysis of external environment factor sub-scale was carried out. Factors are extracted according to a standard characteristic value greater than 1. Variables with high coefficients are classified into one factor category; and finally, 3 first-class indicators. 8 second-level indicators, and 37 observation noints are reconstructed.
基金Sponsored by National Natural Science Foundation of China (21231002,21276026,21271023,21173021,91022006,11202193,11172276,and 11072225)the 111 Project ( B07012)+1 种基金the Program of Cooperation of the Beijing Education Commission ( 20091739006)Specialized Research Fund for the Doctoral Program of Higher Education ( 20101101110031)
文摘The recent research progress of structure- and size-controlled micro/nano-energetic materials is reviewed, which properties are fundamentally different from those of their corresponding bulk materials. The development of the construction strategies for achieving zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) micro/nanostructures from energetic molecules is introduced. Also, an overview of the unique properties induced by micro/nanostructures and size effects is provided. Special emphasis is focused on the size-dependent properties that are different from those of the conventional micro-sized energetic materials, such as thermal decomposition, sensitivity, combustion and detonation, and compaction behaviors. A conclusion and our view of the future development of micro/nano-energetic materials and devices are given.
文摘With high rock slope in shiplock area, thin reinforced concrete lining walls are constructed for the shiplock system. The construction technology involves much complicated structures in formwork, frequent interference due to crossover working procedures, tight time schedule, high quality of reinforced concrete and showcase appearance requirements, hidden troubles affecting construction safety. With above-mentioned factors in consideration, a single-side-separated sliding formwork technology advanced from past sliding formwork experiences has been developed and applied successfully. This new technology is beneficial in quick and safe operation, capable to assure best quality and appearance of shiplock concrete works, and has filled up the gap in terms of construction sliding formwork in our country.
