The Manufacture of the Grinding Wheels Based on the Ca–K Geopolymer Matrix

This article describes the successful manufacture of new grinding wheels based on a binding agent from a clay substance and blast-furnace slag (the Ca–K geopolymer matrix) on industrial presses. Trained factory staff of the company Best – Business, a.s. tested the pressing process for the manufacture of geopolymer-bonded wheels and verified their quality by factory control equipment (Grindo Sonic and Zeiss-Mackensen methods, test of the safe peripheral speed). The results have shown that the Ca–K geopolymer matrix is suitable for grinding-tool preparation and the grinding-wheel properties are comparable with similar products based on the fired ceramic binding agent.     

叶片数控砂带复合磨削加工方法的研究

在对叶片进行数控铣削和砂带抛光磨削的研究基础上,提出了一种叶片数控砂带复合磨削加工的方法.该方法采用了一种刚柔组合的砂带磨削接触轮,兼有切削和抛光的功效.它使叶片的切削加工和抛光加工合二为一,不仅提高了加工效率,也大大降低了生产成本.     

基于层次分析的装载机安全评价方法研究

装载机保有量大、监管机制不健全、事故频发,因此对装载机安全状况的研究已显得非常必要.基于对安全事故的调查和故障统计分析,首先通过风险分析方法查找装载机的风险因素,运用层次分析法建立了装载机安全评价指标体系;应用模糊综合评价方法,建立模糊决策模型;进而综合运用层次分析法和模糊综合评价方法,建立了装载机安全综合评价模型.最后,通过实例应用验证了该评价方法的合理性,为实现装载机分类监管提供了依据.     

轮毂闭式反挤压成形工艺研究

汽车轻量化是世界汽车发展大趋势.试验证明,汽车整备质量每减少100kg,百公里油耗可降低0.3～0.8L.目前大部分汽车安装的轮毂为铸造铝合金轮毂(以乘用车为主)或钢质车轮(以商用车为主).锻造铝合金轮毂重量比铸造铝合金轮毂的重量轻10％左右,比钢质轮毂重量轻2/3左右.因此,采用锻造铝合金轮毂符合汽车轻量化发展的大趋...     

一种汽车轮毂识别方法研究

以桑塔纳14寸轮毂为研究对象,Halcon软件为研究工具,提出一种基于canny算子的轮毂区域识别方法.具体的,采集均匀光源下的轮毂图像,通过灰度化、二值化、高斯滤波、膨胀处理从原始图像中提取"战斧"形区域与模板匹配,实现轮毂区域识别.研究结果表明该方法对轮毂"战斧"形区域匹配良好,同时适用于其它类型轮毂区域识别,为轮...     

矩形箱涵顶管掘进机刀盘仿形组合形式的研究

矩形箱涵顶管掘进机主要用于公路立交涵洞建设.本文从立交涵洞建设的特点出发,分析不同刀盘组合对工程质量的影响,提出了多刀盘仿形组合的新思路.     

基于整槽偏移对齿槽转矩和铁心损耗的研究

为削弱电动汽车轮毂电机的齿槽转矩和铁心损耗,提出一种基于定子整槽偏移的方法对上述问题进行研究。推导电动汽车轮毂电机齿槽转矩和铁心损耗计算公式,确定轮毂电机的参数,建立轮毂电机几何模型;将各个不同偏角的模型导入有限元仿真模型中,分别对齿槽转矩和铁心损耗进行仿真计算,并验证模型的正确性。结果表明：整槽偏移角为3°时的轮毂电机模型,其齿槽转矩和铁心损耗均能取到最优值,且齿槽转矩降低幅度约为98%、铁心损耗降低幅度约为65%、一次谐波降低幅度约为96%。仿真结果验证了基于定子整槽偏移的方法对齿槽转矩、铁心损耗和一次谐波具有明显的抑制作用。所提方法为电动汽车轮毂电机齿槽转矩和铁心损耗的优化设计提供了参考。     

预制装配式混凝土电缆沟力学性能数值模拟分析

为研究预制装配化电缆沟在车辆荷载作用下的受力情况,针对一种预制装配式电缆沟构造形式,采用精细化有限元数值仿真对其进行了模拟分析,探究了该电缆沟在不同汽车轮压荷载、不同覆土厚度条件下的结构应力分布和位移变化规律.结果表明:在设计荷载作用下,预制装配式电缆沟的受力和变形能够满足要求,车辆轮压的作用位置和覆土厚度对结构顶板底...     

Determining operations affected by delay in predictive train timetables

Constructing train schedules is vital in railways. This complex and time consuming task is however made more difficult by additional requirements to make train schedules robust to delays and other disruptions. For a timetable to be regarded as robust, it should be insensitive to delays of a specified level and its performance with respect to a given metric, should be within given tolerances. In other words the effect of delays should be identifiable and should be shown to be minimal. To this end, a sensitivity analysis is proposed that identifies affected operations. More specifically a sensitivity analysis for determining what operation delays cause each operation to be affected is proposed. The information provided by this analysis gives another measure of timetable robustness and also provides control information that can be used when delays occur in practice. Several algorithms are proposed to identify this information and they utilise a disjunctive graph model of train operations. Upon completion the sets of affected operations can also be used to define the impact of all delays without further disjunctive graph evaluations.     

Improving robustness of rolling stock circulations in rapid transit networks

The rolling stock circulation depends on two different problems: the rolling stock assignment and the train routing problems, which up to now have been solved sequentially. We propose a new approach to obtain better and more robust circulations of the rolling stock train units, solving the rolling stock assignment while accounting for the train routing problem. Here robustness means that difficult shunting operations are selectively penalized and propagated delays together with the need for human resources are minimized. This new integrated approach provides a huge model. Then, we solve the integrated model using Benders decomposition, where the main decision is the rolling stock assignment and the train routing is in the second level. For computational reasons we propose a heuristic based on Benders decomposition. Computational experiments show how the current solution operated by RENFE (the main Spanish train operator) can be improved: more robust and efficient solutions are obtained.