为进一步提高传统锅炉汽包水位控制系统的响应速度、抗干扰能力和鲁棒性,提出一种基于全程非线性积分滑模面与扰动补偿的内模滑模控制策略。采用内模控制结构补偿时滞对系统的影响,运用滑模控制律提高系统的鲁棒性,设计基于内模控制结...为进一步提高传统锅炉汽包水位控制系统的响应速度、抗干扰能力和鲁棒性,提出一种基于全程非线性积分滑模面与扰动补偿的内模滑模控制策略。采用内模控制结构补偿时滞对系统的影响,运用滑模控制律提高系统的鲁棒性,设计基于内模控制结构的全程非线性积分滑模面的滑模控制律(Internal Model Control Structure with Global Non-Integral Sliding Mode Control Law,IM-GNISMC),不仅可改善系统的暂态性能,而且能消除滑模趋近阶段,使系统具有全程鲁棒性。由于锅炉汽包水位是积分非自平衡系统,为改善系统的抗干扰能力,并消除阶跃扰动后的稳态误差,设计扰动抑制控制器。进行理论分析和仿真验证,并与三冲量串级比例-积分-微分(Proportional Integral Differential,PID)控制和内模控制相比较。仿真结果表明:设计的控制器具有响应速度快、超调量小和鲁棒性强等特点。展开更多
Regarding the complexity and inconsistency of results in existing evaluation methods of mine cooling system, this paper clarifies the advantages, disadvantages and application of various mine cooling systems through p...Regarding the complexity and inconsistency of results in existing evaluation methods of mine cooling system, this paper clarifies the advantages, disadvantages and application of various mine cooling systems through principle analysis, and divides all the cooling systems into air-cooling, ice-cooling and water-cooling according to the transportation of cold energy. On this basis, the paper proposes a simple and efficient evaluation method for mine cooling system. The first index of this method is the air temperature at point C which is 15 m away from the return wind corner at working face. A cooling system will be judged ineligible if the air temperature at point C is above 30 °C during operation, because in this case, the combustible gases in coal will sharply overflow, inducing gas incidents. Based on the preliminary judgment of the first index, another two evaluation indexes are proposed based on the cooling ability and dehumidification of an airflow volume of 1000 m3/min at point C to evaluate the investment and operation cost of mine cooling system. This evaluation method has already been successfully applied in the cooling system design of Zhangshuanglou coal mine.展开更多
在新时代复杂的国际形势和我国改革开放进入攻坚期这一特殊的大背景下,思想政治教育作为实现学校立德树人目标的重要途径,对学生的身心发展具有重要影响。因此,进一步对思想政治教育进行研究探索尤为重要。本文借助Cite Space V对校园...在新时代复杂的国际形势和我国改革开放进入攻坚期这一特殊的大背景下,思想政治教育作为实现学校立德树人目标的重要途径,对学生的身心发展具有重要影响。因此,进一步对思想政治教育进行研究探索尤为重要。本文借助Cite Space V对校园文化背景下的思想政治教育相关文献进行分析,得出这一研究领域前沿的演化大致可以分为三个阶段,并预测"高校校园文化建设"和"高校思想政治教育"将成为该领域的发展趋势和前沿。展开更多
Regarding the lack of cold source for underground cooling systems from either mine inflow or return air,field experiments were taken in a high temperature deep coal mine with abundant cold source from surface water. T...Regarding the lack of cold source for underground cooling systems from either mine inflow or return air,field experiments were taken in a high temperature deep coal mine with abundant cold source from surface water. Taking Sanhejian coal mine as an example, this paper introduced the technology scheme of heat disaster governance using surface water cold source. The paper presents the basics of this field experiment at the beginning, following by the design and site layout of the cooling system including the analysis and calculation of cold source. Numerical calculation method is also applied based on the operation parameters to simulate the influence to the surface river ecosystem. The results suggest that the temperature of surface water shall be lower than 34 °C after heat exchange, and when more cooling capacities are needed in the future, increasing the water flow is more favorable than increasing the cooling range of water, which is better for the ecological environment protection.展开更多
An experimental apparatus consisting of a crystal growth room and a crystal growth observation system was developed for the study of the effect of the gravity convection perpendicular to the growth direction on the gr...An experimental apparatus consisting of a crystal growth room and a crystal growth observation system was developed for the study of the effect of the gravity convection perpendicular to the growth direction on the growth process by use of model alloy succinonitrile (SCN)-5wt%ethanol. It was found that the convection improves the stability of the interface and causes the downstream alternation of the cell growth direction because of the dual effect of the Stokes force and the gravity. The second dendrite arm facing the flow comes into being earlier than that at an- other side when the interface transforms cell to dendrite. Then the dendrite at the side facing the flow comes into being earlier. The second dendrite arm facing the flow grows faster and is more developed than that at another side. In addition, the primary dendrite arm spacing increases and the dendrite tip radius decreases un- der the gravity convection.展开更多
文摘为进一步提高传统锅炉汽包水位控制系统的响应速度、抗干扰能力和鲁棒性,提出一种基于全程非线性积分滑模面与扰动补偿的内模滑模控制策略。采用内模控制结构补偿时滞对系统的影响,运用滑模控制律提高系统的鲁棒性,设计基于内模控制结构的全程非线性积分滑模面的滑模控制律(Internal Model Control Structure with Global Non-Integral Sliding Mode Control Law,IM-GNISMC),不仅可改善系统的暂态性能,而且能消除滑模趋近阶段,使系统具有全程鲁棒性。由于锅炉汽包水位是积分非自平衡系统,为改善系统的抗干扰能力,并消除阶跃扰动后的稳态误差,设计扰动抑制控制器。进行理论分析和仿真验证,并与三冲量串级比例-积分-微分(Proportional Integral Differential,PID)控制和内模控制相比较。仿真结果表明:设计的控制器具有响应速度快、超调量小和鲁棒性强等特点。
基金supported by the key project of National Natural Science Foundation ‘‘Deep Heat Governance and Utilization’’ (Nos.51134005 and 41402273)the Doctoral Fund of Ministry of Education (No. 20130023110021)
文摘Regarding the complexity and inconsistency of results in existing evaluation methods of mine cooling system, this paper clarifies the advantages, disadvantages and application of various mine cooling systems through principle analysis, and divides all the cooling systems into air-cooling, ice-cooling and water-cooling according to the transportation of cold energy. On this basis, the paper proposes a simple and efficient evaluation method for mine cooling system. The first index of this method is the air temperature at point C which is 15 m away from the return wind corner at working face. A cooling system will be judged ineligible if the air temperature at point C is above 30 °C during operation, because in this case, the combustible gases in coal will sharply overflow, inducing gas incidents. Based on the preliminary judgment of the first index, another two evaluation indexes are proposed based on the cooling ability and dehumidification of an airflow volume of 1000 m3/min at point C to evaluate the investment and operation cost of mine cooling system. This evaluation method has already been successfully applied in the cooling system design of Zhangshuanglou coal mine.
文摘在新时代复杂的国际形势和我国改革开放进入攻坚期这一特殊的大背景下,思想政治教育作为实现学校立德树人目标的重要途径,对学生的身心发展具有重要影响。因此,进一步对思想政治教育进行研究探索尤为重要。本文借助Cite Space V对校园文化背景下的思想政治教育相关文献进行分析,得出这一研究领域前沿的演化大致可以分为三个阶段,并预测"高校校园文化建设"和"高校思想政治教育"将成为该领域的发展趋势和前沿。
基金supported by the Key Project of National Natural Science Foundation‘‘Deep Heat Governance and Utilization’’(No.51134005)the Doctoral Fund of Ministry of Education(No.20120023120004)
文摘Regarding the lack of cold source for underground cooling systems from either mine inflow or return air,field experiments were taken in a high temperature deep coal mine with abundant cold source from surface water. Taking Sanhejian coal mine as an example, this paper introduced the technology scheme of heat disaster governance using surface water cold source. The paper presents the basics of this field experiment at the beginning, following by the design and site layout of the cooling system including the analysis and calculation of cold source. Numerical calculation method is also applied based on the operation parameters to simulate the influence to the surface river ecosystem. The results suggest that the temperature of surface water shall be lower than 34 °C after heat exchange, and when more cooling capacities are needed in the future, increasing the water flow is more favorable than increasing the cooling range of water, which is better for the ecological environment protection.
基金the National Natural Science Foundation of China (Grant Nos. 50331040 and 60171043)
文摘An experimental apparatus consisting of a crystal growth room and a crystal growth observation system was developed for the study of the effect of the gravity convection perpendicular to the growth direction on the growth process by use of model alloy succinonitrile (SCN)-5wt%ethanol. It was found that the convection improves the stability of the interface and causes the downstream alternation of the cell growth direction because of the dual effect of the Stokes force and the gravity. The second dendrite arm facing the flow comes into being earlier than that at an- other side when the interface transforms cell to dendrite. Then the dendrite at the side facing the flow comes into being earlier. The second dendrite arm facing the flow grows faster and is more developed than that at another side. In addition, the primary dendrite arm spacing increases and the dendrite tip radius decreases un- der the gravity convection.
