The goal of economic opening to the outside world is an important basis for formulating and implementing the policy of opening. Different economic development strategies have different requirements for the degree of e...The goal of economic opening to the outside world is an important basis for formulating and implementing the policy of opening. Different economic development strategies have different requirements for the degree of economic opening to the outside world. Guizhou should implement the open economy and adopt the export-oriented development strategy, which objectively requires Guizhou to gradually improve the degree of opening to the outside world.展开更多
电力电子柔性化和分布式发电(DG)消纳是配电网研究的2个热点问题,揭示了配电网柔性度对DG消纳的影响规律和机理。首先,介绍了配电网柔性度的概念,并改进了柔性度的定义。然后,以典型接线模式和IEEE RBTS-Bus4扩展算例为研究对象,观察随...电力电子柔性化和分布式发电(DG)消纳是配电网研究的2个热点问题,揭示了配电网柔性度对DG消纳的影响规律和机理。首先,介绍了配电网柔性度的概念,并改进了柔性度的定义。然后,以典型接线模式和IEEE RBTS-Bus4扩展算例为研究对象,观察随柔性度升高时DG消纳率的变化,并分析规律和机理。研究发现,配电网柔性化并非都能提升DG消纳,存在一个起效条件:智能软开关(soft open point,SOP)某一侧馈线存在DG相对负荷的盈余,同时另一侧存在DG缺额。然而满足起效条件后,消纳率和柔性度之间的规律性仍未显现。提出分析消纳提升限制条件和按SOP安装次序观察的2种方法,发现了隐藏的规律:当存在消纳提升可用空间且无SOP容量限制下,或者同一SOP安装次序下,柔性度和消纳率才具有正相关关系。发现的规律机理为指导配电网的柔性化发展和DG消纳提供了新的理论依据。展开更多
Backfill mining is one of the most important technical means for controlling strata movement and reducing surface subsidence and environmental damage during exploitation of underground coal resources. Ensuring the sta...Backfill mining is one of the most important technical means for controlling strata movement and reducing surface subsidence and environmental damage during exploitation of underground coal resources. Ensuring the stability of the backfill bodies is the primary prerequisite for maintaining the safety of the backfilling working face, and the loading characteristics of backfill are closely related to the deformation and subsidence of the roof. Elastic thin plate model was used to explore the non-uniform subsidence law of the roof, and then the non-uniform distribution characteristics of backfill bodies’ load were revealed. Through a self-developed non-uniform loading device combined with acoustic emission (AE) and digital image correlation (DIC) monitoring technology, the synergistic dynamic evolution law of the bearing capacity, apparent crack, and internal fracture of cemented coal gangue backfills (CCGBs) under loads with different degrees of non-uniformity was deeply explored. The results showed that: 1) The uniaxial compressive strength (UCS) of CCGB increased and then decreased with an increase in the degree of non-uniformity of load (DNL). About 40% of DNL was the inflection point of DNL-UCS curve and when DNL exceeded 40%, the strength decreased in a cliff-like manner;2) A positive correlation was observed between the AE ringing count and UCS during the loading process of the specimen, which was manifested by a higher AE ringing count of the high-strength specimen. 3) Shear cracks gradually increased and failure mode of specimens gradually changed from “X” type dominated by tension cracks to inverted “Y” type dominated by shear cracks with an increase in DNL, and the crack opening displacement at the peak stress decreased and then increased. The crack opening displacement at 40% of the DNL was the smallest. This was consistent with the judgment of crack size based on the AE b-value, i. e., it showed the typical characteristics of “small b-value-large crack and large b-value-small crack”. The research results are of significance for preventing the instability and failure of backfill.展开更多
基金Supported by Guizhou Soft Science Project in 2015(2015LSK2012)Major Innovation Support Project of Guizhou Academy of Social Sciences(ZD02)
文摘The goal of economic opening to the outside world is an important basis for formulating and implementing the policy of opening. Different economic development strategies have different requirements for the degree of economic opening to the outside world. Guizhou should implement the open economy and adopt the export-oriented development strategy, which objectively requires Guizhou to gradually improve the degree of opening to the outside world.
文摘电力电子柔性化和分布式发电(DG)消纳是配电网研究的2个热点问题,揭示了配电网柔性度对DG消纳的影响规律和机理。首先,介绍了配电网柔性度的概念,并改进了柔性度的定义。然后,以典型接线模式和IEEE RBTS-Bus4扩展算例为研究对象,观察随柔性度升高时DG消纳率的变化,并分析规律和机理。研究发现,配电网柔性化并非都能提升DG消纳,存在一个起效条件:智能软开关(soft open point,SOP)某一侧馈线存在DG相对负荷的盈余,同时另一侧存在DG缺额。然而满足起效条件后,消纳率和柔性度之间的规律性仍未显现。提出分析消纳提升限制条件和按SOP安装次序观察的2种方法,发现了隐藏的规律:当存在消纳提升可用空间且无SOP容量限制下,或者同一SOP安装次序下,柔性度和消纳率才具有正相关关系。发现的规律机理为指导配电网的柔性化发展和DG消纳提供了新的理论依据。
基金Project(51925402) supported by the National Natural Science Foundation for Distinguished Young Scholars of ChinaProject(202303021211060) supported by the Natural Science Research General Program for Shanxi Provincial Basic Research Program,China+1 种基金Project(U22A20169) supported by the Joint Fund Project of National Natural Science Foundation of ChinaProjects(2021SX-TD001, 2021SX-TD002) supported by the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering,China。
文摘Backfill mining is one of the most important technical means for controlling strata movement and reducing surface subsidence and environmental damage during exploitation of underground coal resources. Ensuring the stability of the backfill bodies is the primary prerequisite for maintaining the safety of the backfilling working face, and the loading characteristics of backfill are closely related to the deformation and subsidence of the roof. Elastic thin plate model was used to explore the non-uniform subsidence law of the roof, and then the non-uniform distribution characteristics of backfill bodies’ load were revealed. Through a self-developed non-uniform loading device combined with acoustic emission (AE) and digital image correlation (DIC) monitoring technology, the synergistic dynamic evolution law of the bearing capacity, apparent crack, and internal fracture of cemented coal gangue backfills (CCGBs) under loads with different degrees of non-uniformity was deeply explored. The results showed that: 1) The uniaxial compressive strength (UCS) of CCGB increased and then decreased with an increase in the degree of non-uniformity of load (DNL). About 40% of DNL was the inflection point of DNL-UCS curve and when DNL exceeded 40%, the strength decreased in a cliff-like manner;2) A positive correlation was observed between the AE ringing count and UCS during the loading process of the specimen, which was manifested by a higher AE ringing count of the high-strength specimen. 3) Shear cracks gradually increased and failure mode of specimens gradually changed from “X” type dominated by tension cracks to inverted “Y” type dominated by shear cracks with an increase in DNL, and the crack opening displacement at the peak stress decreased and then increased. The crack opening displacement at 40% of the DNL was the smallest. This was consistent with the judgment of crack size based on the AE b-value, i. e., it showed the typical characteristics of “small b-value-large crack and large b-value-small crack”. The research results are of significance for preventing the instability and failure of backfill.
