叉车驱动轮功率测试系统设计

针对叉车系统驱动轮的使用性能和可靠性问题,通过构建测量模块、载荷模拟模块、传动模块和转速控制模决, 设计了一种叉车驱动轮功率测试系统。建立了驱动轮转速控制系统模型,通过磁粉制动器和液压加载模拟叉车运行时 驱动轮所受阻力,并由控制器实现驱动轮的转速控制。实验表明所设计的功率测试系统能有效测量驱动轮的阻力矩和 转速等参数,并得到功率参数,从而实现驱动轮动力特性的测试。     

新型铜基结合剂金刚石磨边轮磨削性能的研究

在新型铜基结合剂CSF中添加Fe、Cr、Mo等粉末,采用真空热压法和高频焊接法制成金刚石磨边轮,通过扫描电镜观察其显微组织,将该磨边轮应用于磨削陶瓷砖、花岗岩和大理石等不同材料,研究其磨削性能.结果表明,由CSF结合剂烧结的金刚石磨边轮组织致密,可完成对陶瓷砖、花岗岩、大理石等材料的磨削.通过对比可知,该磨边轮更适合应用于陶瓷砖的加工,在磨削陶瓷砖时磨边轮刀头的磨损与材料的磨损保持较好匹配,磨边轮的耐磨度更大、锋利度更高,表现出优异的磨削性能,使用寿命长于普通Cu-Sn-Co基体金刚石磨边轮.     

从考古资料看青藏高原史前制陶业的发展历程

考古资料表明青海民和阳洼坡、乐都柳湾、同德宗日,西藏昌都卡若、拉萨曲贡等地均有陶器出土,分别隶属于仰韶、马家窑、齐家、卡若、卡约、辛店等考古文化谱系。青藏高原是我国史前制陶业较为发达的地区之一,河湟地区的彩陶文化更是享誉中外。青藏高原史前制陶工艺起初多用泥条盘筑法,小型器为手捏而成,大约距今4 000年左右,出现慢轮修整技术。随着青铜冶炼技术的出现、推广及游牧业的兴起,大约距今3 500年左右,青藏高原彩陶制作技艺开始衰落。青藏高原不同考古文化类型陶器各具特色,同时也体现出前后继承、交叉影响的特点。     

Application of ridge regression and factor analysis in design and production of alloy wheels

This study proposes using statistical approaches to help with both the design and manufacture of wheels. The quality of a wheel is represented by the mechanical properties of spokes. Variation in the mechanical properties of different wheels is attributed to two sources, i.e. between-model variation and within-model variation. The between-model variation is due to different shapes of different wheel models. To model the effect of shapes on the mechanical properties, we first specify eight shape variables potentially critical to the mechanical properties, and then we collect relevant data on 18-wheel models and perform ridge regression to find the effects of these variables on the mechanical properties. These results are linked to the solidification theory of the A356 alloy. The within-model variation is due to natural variability and process abnormality. We extract mechanical data of a particular wheel model from the database. Factor analysis is employed to analyze the data with a view to identifying the latent factors behind the mechanical properties. We then look into the microstructure of the alloy to corroborate the fact that these two latent factors are essentially the Si phase and the Mg₂Si phase, respectively. These results can be used to efficiently identify the root cause when the manufacturing process goes wrong.     

Ojibwe lesbian visual AIDS: On the Red Road with Carole laFavor,Her Giveaway (1988), and Native LGBTQ2 film history

ABSTRACT

After a century of suppression across the Silent, Classic, and New Hollywood eras, Native Lesbian/Gay media began to proliferate in the post-AIDS 1980s and into the second millennium. Her Giveaway: A Spiritual Journey with AIDS (1988) is a key tribal health AIDS video that exemplified a new contemporary media combination of visual, erotic, and theological sovereignty. The video's central Red Road narrative by the lesbian, Ojibwe, and AIDS/HIV+ spokesperson Carole laFavor emphasizes Native American traditional healing methods involving the medicine wheel and a reclamation of Native lesbian/gay identity.     

轮图与舵轮图的超边优美标号

1994年, Mitchem和Simoson在研究标号图的问题时,提出了超边优美图的概念。在随后的研究中,一些图被证明具有超边优美性质,同时关于超边优美图的一些猜想也被提出。本文利用递归方法构造了轮图Wn与舵轮图Hn的超边优美标号,证明了这两类图是超边优美图。     

高精度紫铜薄板件的平面加工技术

本文针对高精度紫铜薄板件的平面加工因铣削加工易变形,难以保证精度要求的问题,从切削加工变形机理和切削受力分析出发,提出了用铣削作粗加工,磨削作精加工的工艺方法,在实际生产中,取得了良好的效果。     

Degradation data analysis for samples under unequal operating conditions: a case study on train wheels

Traditionally, reliability assessment of devices has been based on life tests (LTs) or accelerated life tests (ALTs). However, these approaches are not practical for high-reliability devices which are not likely to fail in experiments of reasonable length. For these devices, LTs or ALTs will end up with a high censoring rate compromising the traditional estimation methods. An alternative approach is to monitor the devices for a period of time and assess their reliability from the changes in performance (degradation) observed during the experiment. In this paper, we present a model to evaluate the problem of train wheel degradation, which is related to the failure modes of train derailments. We first identify the most significant working conditions affecting the wheel wear using a nonlinear mixed-effects (NLME) model where the log-rate of wear is a linear function of some working conditions such as side, truck and axle positions. Next, we estimate the failure time distribution by working condition analytically. Point and interval estimates of reliability figures by working condition are also obtained. We compare the results of the analysis via an NLME to the ones obtained by an approximate degradation analysis.     

我国居民位置消费行为的动因分析

从经济学中的几种效应，对我国的阶层情况及奢侈品市场的特殊性对我国居民消费行为的动因进行分析，并得出结论和政策启示。     

陶瓷零件磨削加工质量研究

从陶瓷零件的加工技术的角度，叙述了陶瓷零件的磨削机理，分析影响瓷表面的加工质量的因素。