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排序方式: 共有674条查询结果,搜索用时 0 毫秒
1.
超高分子量聚乙烯衬板在煤仓中的应用 总被引:2,自引:0,他引:2
介绍了井底煤仓溜煤斜面采用超高分子量聚乙烯衬板安装及应用情况 ,对井底煤仓棚煤原因及解决办法进行了探讨 相似文献
2.
渠道断面优化是控制农田水利工程成本的重要因素,已有的渠道断面优化研究以梯形渠道为主,对U型渠道研究较少。以优化U型渠道深度、圆弧半径和直线段外倾角为目标,建立以U型渠道过水断面面积最小为目标函数、满足设计流量要求的数学优化模型。根据U型渠道水力计算的复杂性,利用引入协调行为的两阶段人工鱼群算法,对渠道断面设计进行优化。优化结果满足边坡稳定等约束条件。将模型应用于连云港市赣榆区黑林镇土地整理项目,10条斗渠过水断面面积均减小,优化后占地面积共减少28.603 m~2,占原占地面积的5.0%。 相似文献
3.
U型衬砌渠道具有良好的整体性和冻胀适应性,但在冬季仍极易因土体冻胀而导致破坏。考虑渠基冻土与衬砌接触面冻结的非线性特性和冻土、混凝土材料的塑性特征,建立能分析渠道基土与衬砌间挤压、脱开及滑移等接触力学行为的渠道冻胀破坏热力耦合数值模型。以宝鸡峡灌区塬下北干渠为原型渠道,按照模型是否考虑接触分别进行冻胀数值模拟,并对模拟结果进行对比分析。结果表明:考虑接触的模型模拟结果与原型实测值更相符,更能合理地解释U型渠道冻胀在渠底与阴坡衔接处冻胀量最小;考虑接触的混凝土塑性应变最大值是不考虑接触时的3.76倍;考虑接触的法向冻胀力和切向冻结力更均匀,最大值均减少1.5~3.0倍,应力集中现象减弱,更能反映混凝土衬砌板与渠基土之间的滑移变形与破坏准则的相互作用。研究结果为U型衬砌渠道冻胀破坏规律提供了分析方法。 相似文献
4.
Gang Liu Zhongqin Lin Youxia Bao J. Cao 《Journal of Materials Engineering and Performance》2002,11(1):64-70
Springback is the main concern in U-shaped part forming, which would adversely affect desired part geometries. The use of
variable blankholder force in the forming process is one effective method to reduce springback. However, there has not been
a systematic way to determine the blankholder force trajectory. In this article, a methodology of obtaining this blankholder
force trajectory in forming a U-shaped part that considers the wrinkling limit and fracture limit in the forming process was
proposed. The method was validated numerically by using the Finite Element Method to simulate the benchmark of a 2-D draw
bending problem in NUMISHEET’93. With the calculated blankholder force trajectory, higher forming quality was obtained and
compared with constant blankholder force cases. Springback was kept at a minimum while avoiding cracking. 相似文献
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Fluctuations in market demands, increased mobility of workers and changing employment practices as well as companies’ increased respect for individual differences of workers have led to the phenomenon that workers with large efficiency differences work together in the same production line in manufacturing companies. In a traditional travelling production line (TrPL), low-efficiency workers can block the work of higher efficiency workers. To increase the production capacity of a travelling line composed of workers with different efficiencies, a chasing-overtaking mechanism was established and used to achieve line production capacity and efficiency improvement. A formula to calculate the production capacity of two workers with different efficiencies was derived and validated. A simulation performed to analyse the differences between the ‘chasing-overtaking’ production line (COPL), TrPL and the classic ‘bucket brigade’ production line (BBPL) with respect to production capacity, working time utilisation and equipment utilisation demonstrated that the COPL provides good production capacity and adaptability to worker differences. Finally, the statistical analysis verified that the COPL has a higher production capacity, average worker working hour utilisation rate and equipment utilisation rate than the BBPL and TrPL. 相似文献
7.
J. Mukund Nilakantan 《工程优选》2016,48(2):231-252
Automation in an assembly line can be achieved using robots. In robotic U-shaped assembly line balancing (RUALB), robots are assigned to workstations to perform the assembly tasks on a U-shaped assembly line. The robots are expected to perform multiple tasks, because of their capabilities. U-shaped assembly line problems are derived from traditional assembly line problems and are relatively new. Tasks are assigned to the workstations when either all of their predecessors or all of their successors have already been assigned to workstations. The objective function considered in this article is to maximize the cycle time of the assembly line, which in turn helps to maximize the production rate of the assembly line. RUALB aims at the optimal assignment of tasks to the workstations and selection of the best fit robot to the workstations in a manner such that the cycle time is minimized. To solve this problem, a particle swarm optimization algorithm embedded with a heuristic allocation (consecutive) procedure is proposed. The consecutive heuristic is used to allocate the tasks to the workstation and to assign a best fit robot to that workstation. The proposed algorithm is evaluated using a wide variety of data sets. The results indicate that robotic U-shaped assembly lines perform better than robotic straight assembly lines in terms of cycle time. 相似文献
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介绍了U型薄壁渡槽槽身大跨度的结构施工技术,即:模板支撑桁架的型式,模板支撑调节器的选用,按刚度、强度及稳定性的要求确定的模板,以及混凝土浇筑关键控制工序和拆模后的养护.此外,还介绍了槽身止水的施工. 相似文献