Balancing of parallel U-shaped assembly lines

A new hybrid assembly line design, called parallel U-shaped assembly line system, is introduced and characterised along with numerical examples for the first time. Different from existing studies on U-shaped lines, we combine the advantages of two individual line configurations (namely parallel lines and U-shaped lines) and create an opportunity for assigning tasks to multi-line workstations located in between two adjacent U-shaped lines with the aim of maximising resource utilisation. Utilisation of crossover workstations, in which tasks from opposite areas of a same U-shaped line can be performed, is also one of the main advantages of the U-shaped lines. As in traditional U-shaped line configurations, the newly proposed line configuration also supports the utilisation of crossover workstations. An efficient heuristic algorithm is developed to find well-balanced solutions for the proposed line configurations. Test cases derived from existing studies and modified in accordance with the proposed system in this study are solved using the proposed heuristic algorithm. The comparison of results obtained when the lines are balanced independently and when the lines are balanced together (in parallel to each other) clearly indicates that the parallelisation of U-shaped lines helps decrease the need for workforce significantly.     

Experimental and numerical studies of a U-shaped solar energy collector to track the maximum CPV/T system output by varying the flow rate

In the last decade, no comprehensive numerical and experimental analyses have been performed to find the maximum possible power generation from a concentrated photovoltaic thermal (CPV/T) system by varying the flow rate of the fluid. This paper describes numerical and experimental studies of a U-shaped solar energy collector model of a CPV/T system, with the goal of determining the maximal thermal and electrical power outputs against a specific volumetric flow rate also called an optimum flow rate. The CPV/T system was based on the union of 8 triple junction solar cells, 8 SOG Fresnel lenses, effective dual-axis tracking, and a forced cooling system. Analyses were performed by changing the flow rate of the working fluid at a considered solar irradiation and ambient temperature. The thermal and electrical power outputs also varied with changes in the ambient temperature and available solar radiation. The relatively high value of CPV/T power was observed against the optimum flow rate at a given irradiation and ambient temperature. Analysis of the energy of the U- shaped solar energy collector system was evaluated experimentally. The numerical results and experimental measurements of the U-shaped solar energy collector model showed great harmony, with minimal deviations of <7% between them.     

泵高速用平底直U形卸荷槽的研究与分析

为解决高速齿轮泵困油的卸荷问题,提出了一款极易加工的平底直U形卸荷槽及形位尺寸;并与传统的矩形卸荷槽进行卸荷面积和困油压力的实例对比。结果表明:U形最大卸荷面积增加了13.5%,能有效解决最小困油容积附近的卸荷能力不足问题,且其结构与加工简单;在8 000 r/min高转速下, U形卸荷槽困油的压力峰值增加率为15.9%,压力谷值为-0.26 MPa,其困油现象相对轻微;而矩形卸荷槽的压力峰值增加率和压力谷值分别为25.1%和-0.61 MPa,其困油现象相对严重。     

U形接触片多工位级进模设计与制造

针对U形接触片的技术要求,确定了合理的冲压工艺方案,阐述了该多工位级进模设计要点,产品质量达到设计要求。同时,还介绍了楔块装置及磷铜薄片整形的微调装置。     

复杂环境深厚淤泥河道桥桩施工技术

环岛西路桥梁工程首先对桥梁区域道路进行了划分,该区域考虑下穿综合管沟基坑的作业,综合考虑桥梁桩基施工,采取迁改临时河道,并对河道进行了疏通,同时对软基和桥桩进行了处理,保证了施工质量。     

大倾角炮采放顶煤矿压显现特征

通过对郑煤集团芦沟煤矿首个大倾角炮采放顶煤工作面进行矿压观测和数值模拟,分析得出大倾角炮采放顶煤工作面在开采过程中支架阻力为降阻状态分布,倾向支承压力两端高、中间低呈"马鞍形",且区段轨道平巷支承压力峰值明显高于区段回风平巷,维护困难。     

综放采场顶煤压裂机理的实验研究

采动岩体裂隙演化规律的定量描述是岩石力学的重要课题之一。通过模拟支承压力对硬煤、软煤和中硬煤300 mm×300 mm×300 mm大煤样的压裂过程,运用分形几何理论研究了顶煤在支承压力峰值前后作用下裂隙的演化规律。研究结果表明,裂隙分维和支承压力具有良好的多项式定量关系。同时得出了基于损伤力学的顶煤压裂本构方程,为综放开采数值分析、工艺及参数选择提供了科学依据。     

软土地基条件下桥台受力分析及病害诊治

分析了软土地基作用下桥台受力情况,对于桥台产生的病害原因进行深入分析,总结软基桥台稳定的影响因素,并提出具体处理方案,针对此类情况从设计及施工角度提出有效的措施。     

软基桥台位移病害分析及预防措施

在软土地基中 ,因桥台位移造成的桥梁破坏比较突出 ,结合连云港市高等级公路已建桥梁 ,对桥台位移产生的病害进行分析 ,并从设计、施工等方面提出相应的预防措施及注意事项。     

公路桥涵台背设计的理论方法探讨

介绍了近年来国内外研究人员对桥涵台背的设计研究方法，结合桥涵与台背结构组合的设计原则，从搭板的型式、坡度、长度、厚度、配筋等方面提出了搭板设计的方法。