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991.
992.
993.
Soil and water loss in the Lancang River-Mekong River watershed (in Yunnan section, China) and its control measures 总被引:1,自引:0,他引:1
MekongRiverisoriginatedinthenorthernrangeofTibetQinghaiPlateauofChina,flowingthroughsixcountries,theyareChina(YunnanProvince),M?.. 相似文献
994.
995.
996.
运用熵权法、耦合协调模型和地理探测器分析了2008—2019年四川省乡村振兴与乡村旅游发展水平与耦合协调度的演变特征及驱动因子,总结了各市(州)的发展类型,并提出差异化发展策略。结果表明:①四川省乡村振兴与乡村旅游发展水平呈上升趋势,攀枝花乡村振兴发展缓慢,成都、阿坝州、宜宾是乡村旅游发展的重心。②乡村振兴与乡村旅游呈耦合协调发展趋势,具有显著的空间异质性,以濒临失调和勉强协调为主,呈东南低、北部高的空间格局。③星级农家乐和乡村酒店数量、全社会固定资产投资、国家级非物质文化遗产数、旅游总收入占GDP比重等是影响乡村振兴与乡村旅游协调发展的主要因子。 相似文献
997.
针对神东矿区大柳塔煤矿采用7.0 m采高综采面回采5-2煤三盘区时回采巷道出现不同程度的变形破坏现象,采用现场实测的方法对52304及52303工作面回风顺槽之间的区段煤柱进行了巷道变形及应力变化规律的监测,并运用FLAC3D数值模拟软件对不同埋深条件下两工作面之间区段煤柱的应力分布规律进行了模拟,最后总结分析了回采巷道变形破坏的机理,并得出采空区段煤柱的失稳是造成回采巷道变形破坏的根本原因。从而为巷道的合理布置及相应控制对策的提出提供基础数据,以保证矿井安全高效的生产。 相似文献
998.
为获得某金矿尾砂胶结充填材料最优配比,基于试验结果,以海水比例、灰砂比和料浆质量浓度为输入参数,以充填体强度、塌落度及泌水率为输出参数,建立了充填配比与其响应量的高斯过程回归模型,分析了不同因素对充填性能的影响程度;采用遗传算法对高斯过程回归模型进行多目标参数优化,获得了Pareto非劣解,在此基础上,引入多属性决策的TOPSIS法对Pareto非劣解进行方案优选,确定了充填最优配比。研究结果表明:高斯过程回归模型相对误差值均小于6%,可靠性高;灰砂比及料浆质量浓度对充填性能影响较为显著,采用海水作为充填水源将降低充填体的强度;经优化后的充填配比与试验结果相符。 相似文献
999.
In recent years, significant progress has been made to ensure that process industries are among the safest workplaces in the world. However, with the increasing complexity of existing technologies and new problems brought about by emerging technologies, a strong need still exists to study the fundamentals of process safety and predict possible scenarios. This is attained by conducting the corresponding consequence modeling and risk assessments. As a result of the continuous advancement of Computational Fluid Dynamics (CFD) tools and exponentially increased computation capabilities along with better understandings of the underlying physics, CFD simulations have been applied widely in the areas of process safety and loss prevention to gain new insights, improve existing models, and assess new hazardous scenarios. In this review, 126 papers from 2010 to 2020 have been included in order to systematically categorize and summarize recent applications of CFD for fires, explosions, dispersions of flammable and toxic materials from accidental releases, incident investigations and reconstructions, and other areas of process safety. The advantages of CFD modeling are discussed and the future of CFD applications in this research area is outlined. 相似文献
1000.
With several industrial applications of fluidized bed technology recently commercialized worldwide, it becomes essential to develop safe operation methods for fluidized bed reaction systems (FBRSs) to prevent any influence on their process values, which lead to accidents. To preventing any disaster or malfunction in an FBRS, an emergency shutdown system (ESD) is initiated, closing the reaction system in case of any abnormality by effectively isolating the flammable gas. However, an ESD is also prone to the “inactivation problem,” in which in the case of failure it initiates the emergency shutdown, even when the operating conditions of the reaction system are abnormal. It is also vulnerable to a “malfunction problem,” where the emergency shutdown is performed even when the operating conditions of the reaction system are normal. In this study, these problems were solved by investigating a reaction system through the monitoring of appropriate parameters and setting up of trigger levels, which reflect the uniqueness of an FBRS using an ESD. The parameters were identified by analyzing the scenario leading to an accident. The trigger levels were determined as the points at which the loss is smaller in the presence of an ESD, as compared to the value of the loss function in the presence or absence of an ESD. Furthermore, the ESD design model was applied as a case study in the ammoxidation process of propylene. The results showed that an ESD can prevent an approximately 8 billion yen of loss due to accidents in plant operations, against an investment of 200 million yen. 相似文献