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应尽快结束私人保镖的“地下状态”
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作者 毕定国 《中国社会导刊》 北大核心 2004年第1期25-25,共1页
在广州这个"先富起来"的城市,活跃着一批"私人保镖".他们出现在"老板"左右,时刻准备着与可能出现的危险进行一番决斗.从事保镖工作的夏先生告诉记者,按照他的结交范围判断,广州的私人保镖不少于5000人.
关键词 私人保镖行业 公共选择学 富豪 人身安全感 “地下状态” 政府公共资源
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Effect of discontinuities characteristics on coal mine stability and sustainability: A rock fall prediction approach 被引量:1
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作者 Oraee Kazem Oraee Nikzad +1 位作者 Goodarzi Arash Khajehpour Parham 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2016年第1期65-70,共6页
Rock fall related accidents continue to occur in coal mines,although artificial support mechanisms have been used extensively. Roof stability is primarily determined in many underground mines by a limited number of me... Rock fall related accidents continue to occur in coal mines,although artificial support mechanisms have been used extensively. Roof stability is primarily determined in many underground mines by a limited number of methods that often resort to subjective criteria. It is argued in this paper that stability conditions of mine roof strata,as a key factor in sustainability in coal mines,must be determined by a survey which proactively investigates fundamental aspects of said mine. Failure of rock around the opening happens as a result of both high rock stress conditions and the presence of structural discontinuities. The properties of such discontinuities affect the engineering behavior of rock masses causing wedges or blocks to fall from the roof or sliding out of the walls. A practical rule-based approach to assess the risk of a roof fall is proposed in the paper. The method is based on the analysis of structural data and the geometry and stability of wedges in underground coal mines. In this regard,an accident causing a huge collapse in a coal mine leading to 4 fatalities is illustrated by way of a case study. Horizontal and vertical profiles are prepared by geophysical methods to define the falling zone and its boundaries. The collapse is then modeled by the use of sophisticated computer programs in order to identify the causes of the accident. 展开更多
关键词 DiscontinuitiesRock fallCoal minePredictionUNWEDGESustainability
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Robustness analysis of underground powerhouse construction simulation based on Markov Chain Monte Carlo method 被引量:6
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作者 ZHONG DengHua BI Lei +1 位作者 YU Jia ZHAO MengQi 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2016年第2期252-264,共13页
Scheduling is a major concern in construction planning and management, and current construction simulation research typically targets the shortest total duration. However, uncertainties are inevitable in actual constr... Scheduling is a major concern in construction planning and management, and current construction simulation research typically targets the shortest total duration. However, uncertainties are inevitable in actual construction, which may lead to discrepancies between the actual and planned schedules and increase the risk of total duration delay. Therefore, developing a robust construction scheduling technique is of vital importance for mitigating disturbance and improving completion probability. In the present study, the authors propose a robustness analysis method that involves underground powerhouse construction simulation based on the Markov Chain Monte Carlo(MCMC) method. Specifically, the MCMC method samples construction disturbances by considering the interrelationship between the states of parameters through a Markov state transition probability matrix, which is more robust and efficient than traditional sampling methods such as the Monte Carlo(MC) method. Additionally, a hierarchical simulation model coupling critical path method(CPM) and a cycle operation network(CYCLONE) is built, using which construction duration and robustness criteria can be calculated. Furthermore, a detailed measurement method is presented to quantize the robustness of underground powerhouse construction, and the setting model of the time buffer is proposed based on the MCMC method. The application of this methodology not only considers duration but also robustness, providing scientific guidance for engineering decision making. We analyzed a case study project to demonstrate the effectiveness and superiority of the proposed methodology. 展开更多
关键词 underground powerhouse construction schedule simulation model MCMC method ROBUSTNESS
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