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961.
提出了以风侧流阻最小为目标函数, 传热负荷与迎风面尺寸为约束条件的双金属翅片管换热器优化设计模型, 并开发出了相应的设计软件,成功地进行了在尿素大颗粒工程中五台蒸汽加热器的优化设计。 相似文献
962.
963.
王开荣 《土木建筑与环境工程》1999,21(4):98-101105
文献(1)给出了解等式约束问题的一个方法,它比经典的Lagrange乘子算法所解方程组有更低的维数。本文在(1)的基础上,对非线性等式约束进行了线性逼近,从而构造了近似算法,该法在计算上减少了很多的数值困难。 相似文献
964.
It is postulated that pre-buckling elastic stress pattern in axially compressed right frustum will determine its initial and progressive buckling mode. The elastic stress profiles along the generator and around various diameters of aluminium alloy frustum under axial compression were measured under different boundary constraints. The shape of such profiles was found to be periodic and wavy with relatively high peaks and high stress gradients at a number of points. It is thought that these peaks correspond to the number of lobes in multi-lobe collapse modes, which are observed when the axial loading exceeds the elastic range. These peaks are attributed to all possible imperfections in geometry and dimensions such as variations in thickness, symmetry, generator length and deviation of the axis from being perpendicular to the cross-section. 相似文献
965.
Walter Hussak Shuang-Hua Yang 《国际自动化与计算杂志》2007,4(4):413-421
A formal methodology is proposed to reduce the amount of information displayed to remote human operators at interfaces to large-scale process control plants of a certain type.The reduction proceeds in two stages.In the first stage,minimal reduced subsets of components,which give full information about the state of the whole system,are generated by determining functional dependencies between components.This is achieved by using a temporal logic proof obligation to check whether the state of all components can be inferred from the state of components in a subset in specified situations that the human operator needs to detect,with respect to a finite state machine model of the system and other human operator behavior.Generation of reduced subsets is automated with the help of a temporal logic model checker.The second stage determines the interconnections between components to be displayed in the reduced system so that the natural overall graphical structure of the system is maintained.A formal definition of an aesthetic for the required subgraph of a graph representation of the full system,containing the reduced subset of components,is given for this purpose. The methodology is demonstrated by a case study. 相似文献
966.
《International Journal of Hydrogen Energy》2020,45(3):2094-2104
Today, the utilizations of hydrogen storage systems (HSS), renewable generation units (PV and wind generation) and distributed energy units are increased in the intelligent parking lots (IPL) in order to charge the electric vehicles (EVs) with clean energy sources. In this work, the uncertainties of upstream grid price, the demand of IPL, wind speed, solar irradiation and temperature are modeled via scenario approach based on stochastic programing. Furthermore, the downside risk constraints method (DRCM) is applied to consider risk related to uncertainties to get risk-involved stochastic performance of hydrogen storage based intelligent parking lots of electric vehicles. The proposed risk-based formulation is modeled using mixed-integer linear programming (MIP) which is implemented under GAMS software and solved via CPLEX solver. Two cases namely risk-averse and risk-neutral strategies are studied and compared to show the effects of DRCM implementation. The obtained results demonstrate the expected performance cost (EPC) of IPL is slowly raised while risk-in-cost (RIC) is significantly reduced due to model of risk related to uncertainties. 相似文献
967.
以汾河上游四个水文站月径流资料为基础,选取常用的六种概率分布拟合了月、季、年时间尺度下的径流量,并进行了拟合优度检验,判断出汾河上游水文站不同时间尺度下径流服从的最佳分布函数,根据最佳分布函数计算标准化径流指数,分析不同时间尺度下的水文干旱时空变化特征。结果表明,汾河上游不同站点在不同时间尺度下服从的概率分布并不统一;不同时间尺度下四个水文站的标准化径流指数变化具有较好的一致性;1956~2000年标准化径流指数总体呈下降趋势,水文干旱逐年加重;西北部干旱程度逐渐减轻,东南部干旱严重程度逐渐加重。 相似文献
968.
为研究机械约束和热状态对缸盖与缸垫间热弹性接触非线性问题的影响规律,以某4气门柴油机为研究对象,建立了缸盖-缸垫-机体-螺栓的四体接触关系简化模型。采用增广拉格朗日乘子法作为接触算法,在不同的螺栓预紧力和热状态下,计算了缸盖底板的受力变形,揭示了标定工况热态下机械约束对缸盖底板相关部位接触应力和节点位移的影响规律,及标定预紧力时不同热状态对结果的影响。研究表明:当预紧力为标定值时,施加最高燃烧压力后,标定工况热态下缸盖底板正对缸圈处及排气门侧螺孔处的接触应力与冷态时相近,节点位移有所减小,不同热状态下螺孔处节点位移及正对缸圈处接触应力和节点位移的变化幅值均小于2%;除少数情况外,缸盖底板各相关部位的接触应力和节点位移随预紧力增大而增大。上述研究结果也说明:目前采用常温条件进行缸垫密封性试验基本上能够代表实用状态。 相似文献
969.
970.
This paper proposes an efficient algorithm for considering reactive power and voltage constraints in unit commitment. Because the problem is formulated as a large mixed-integer programming and has a two-level hierarchical structure, the Benders decomposition method is used. Using decomposition, the master problem solves unit commitment, and the subproblem examines reactive power and voltage constraints in each hour to test the feasibility of the unit commitment solution. In the case of infeasibility, a proper constraint (Benders cut) is introduced and placed in the master problem for unit commitment rescheduling. The iterative process between the master and subproblems provides a minimum cost solution for generation scheduling while satisfying reactive power and voltage constraints. The constrained economic dispatch is used in our unit commitment. The constraints in the subproblem are formulated as linear programming with a block-angular structure. So, the Dantzig–Wolfe decomposition is applied in the subproblem to solve large-scale power system problems. A modified IEEE-30 bus system is presented to demonstrate the efficiency of the method. © 1997 by John Wiley and sons, Ltd. 相似文献