An element coupling model (ECM) method was proposed to simulate the global behavior and local damage of a structure.In order to reflect the local damage and improve the computational efficiency,three-dimensional (3D) ...An element coupling model (ECM) method was proposed to simulate the global behavior and local damage of a structure.In order to reflect the local damage and improve the computational efficiency,three-dimensional (3D) solid elements and one-dimensional (1D) beam element were coupled by the multi-point constraint equations.A reduced scale 1?8 model test was simulated by the ECM and a full three dimensional model (3DM) contrastively.The results show that the global behavior and local damages of ECM agree well with the test and 3DM.It is indicated that the proposed method can be used in the structural nonlinear analysis accurately and efficiently.展开更多
Based on Hertz theory of elastic contact and the design theory of ball bearings, a new type of rolling coupling was designed. The two halves of the rolling coupling can be moved relatively by a small axial force when ...Based on Hertz theory of elastic contact and the design theory of ball bearings, a new type of rolling coupling was designed. The two halves of the rolling coupling can be moved relatively by a small axial force when a great moment is exerted on it. The rolling coupling was used to connect the principal axis and the decelerator of continuous extrusion machine and it can greatly decrease the harmful axial forces on the continuous machine. The engineering formulas for the contact stress and distance of apporach of the rolling elements were deduced and the method for designing the rolling couplings was proposed. The formulas for the forces exerted on the rolling element were verified by the experiment.展开更多
高比例新能源的接入对电力系统既是机遇也是挑战:新能源具有清洁低碳的环保优势,但其出力不确定性大、物理惯量低的特点也对系统的频率安全运行带来挑战。针对上述问题,提出一种考虑碳-绿证市场耦合的新能源与储能虚拟惯量-阻尼调度方...高比例新能源的接入对电力系统既是机遇也是挑战:新能源具有清洁低碳的环保优势,但其出力不确定性大、物理惯量低的特点也对系统的频率安全运行带来挑战。针对上述问题,提出一种考虑碳-绿证市场耦合的新能源与储能虚拟惯量-阻尼调度方法。首先,构建包含电力决策、碳交易市场和绿证交易市场三者耦合关系,并计及系统动态频率安全约束的虚拟惯量-阻尼调度优化模型;其次,为降低决策保守性,将不确定性约束建模为整体的联合机会约束形式;然后,采用改进的样本平均近似(modified sample average approximation, MSAA)方法对所提模型进行求解,有效规避常规样本平均近似(sample average approximation, SAA)方法中0-1指示变量导致的计算负担。在IEEE-39节点系统的仿真结果表明:与现有模型和机会约束建模方法相比,所提方法能够根据系统时变扰动需求自适应调整虚拟惯量和下垂阻尼,在满足风险概率5%的前提下,以比固定系数方法低6.03%的成本,确保系统频率偏差在0.5 Hz以内。展现出更好的经济性、低碳性和频率安全性;同时,改进的MSAA方法较传统SAA方法计算时间减少了约90%,可显著提升计算效率。展开更多
基金Project(2007CB714202) supported by the National Key Basic Research Program of ChinaProject(SLDRCE10-B-07) supported by theMinistry of Science and Technology of China
文摘An element coupling model (ECM) method was proposed to simulate the global behavior and local damage of a structure.In order to reflect the local damage and improve the computational efficiency,three-dimensional (3D) solid elements and one-dimensional (1D) beam element were coupled by the multi-point constraint equations.A reduced scale 1?8 model test was simulated by the ECM and a full three dimensional model (3DM) contrastively.The results show that the global behavior and local damages of ECM agree well with the test and 3DM.It is indicated that the proposed method can be used in the structural nonlinear analysis accurately and efficiently.
文摘Based on Hertz theory of elastic contact and the design theory of ball bearings, a new type of rolling coupling was designed. The two halves of the rolling coupling can be moved relatively by a small axial force when a great moment is exerted on it. The rolling coupling was used to connect the principal axis and the decelerator of continuous extrusion machine and it can greatly decrease the harmful axial forces on the continuous machine. The engineering formulas for the contact stress and distance of apporach of the rolling elements were deduced and the method for designing the rolling couplings was proposed. The formulas for the forces exerted on the rolling element were verified by the experiment.
文摘高比例新能源的接入对电力系统既是机遇也是挑战:新能源具有清洁低碳的环保优势,但其出力不确定性大、物理惯量低的特点也对系统的频率安全运行带来挑战。针对上述问题,提出一种考虑碳-绿证市场耦合的新能源与储能虚拟惯量-阻尼调度方法。首先,构建包含电力决策、碳交易市场和绿证交易市场三者耦合关系,并计及系统动态频率安全约束的虚拟惯量-阻尼调度优化模型;其次,为降低决策保守性,将不确定性约束建模为整体的联合机会约束形式;然后,采用改进的样本平均近似(modified sample average approximation, MSAA)方法对所提模型进行求解,有效规避常规样本平均近似(sample average approximation, SAA)方法中0-1指示变量导致的计算负担。在IEEE-39节点系统的仿真结果表明:与现有模型和机会约束建模方法相比,所提方法能够根据系统时变扰动需求自适应调整虚拟惯量和下垂阻尼,在满足风险概率5%的前提下,以比固定系数方法低6.03%的成本,确保系统频率偏差在0.5 Hz以内。展现出更好的经济性、低碳性和频率安全性;同时,改进的MSAA方法较传统SAA方法计算时间减少了约90%,可显著提升计算效率。
