岩石切削过程中破坏机制的离散元分析

利用离散单元方法(DEM)对两种不同属性的花岗石样本模型进行了切割模拟,通过调整不同的切削参数计算并分析了岩石切削过程中的切削力、切削深度、切削比能及切削力倾角的变化规律,从细观上探讨了临界切深对岩石脆性破坏模式和塑性破坏模式及其转变的影响,指出了当切削深度逐渐增大时,破坏模式依次从塑性破坏模式到过渡破坏模式最后转变为脆性破坏模式,同时切削力倾角并不随切削深度变化。将离散单元法分析的结果与实际实验进行了比较,表明该方法是合理的。     

未来弹性与AES

介绍了未来弹性的概念,对将未来弹性引入AES评估标准的优点进行了探讨,以来来弹性的观点分析了第二轮AES候选算法的遴选并提出了具体建议。     

加工电机铜套用的钻钹夹头

我厂生产的永磁直流电机,使用直径20毫米的铜套。它批量大,工序多。我们按铜套的生产工序设计了一付可以同时装夹中心钻、麻花钻和铰刀等四把刀具的夹头,具体如图所示。     

Infrared emission properties and energy transfer in ZnO-SiO2:Yb composites

Intense near-infrared emission at 1 μm has been obtained in ZnO-SiO₂:Yb³⁺ composites via a facile sol-gel method upon broadband ultraviolet light excitation. Systematic optical measurements including static and time-resolved photoluminescence have been performed to elucidate the energy transfer from ZnO quantum dots to Yb³⁺ ions. The dependence of energy transfer efficiency on Yb³⁺ concentration has been investigated in detail. Codoping with Li⁺ ions leads to about twice enhancement of the near-infrared luminescence intensity around 1 μm at room temperature. The enhancement in the luminescence intensity could be mostly attributed to the modification of the local symmetry around Yb³⁺ ions by codoping with Li⁺ ions.     

结肠镜检查者肠道准备无效的原因分析及应对措施

目的:探讨结肠镜检查者肠道准备无效的原因及应对措施.方法:有经验的肠镜检查医师根据肠道清洁效果评价指标进行评价.结果:1313例检查者中有49例肠道准备无效.结论:服药方法、疾病因素、年龄、心理状态、肠镜检查次数等都对肠道准备效果产生了影响.     

Mechanically strong conducting hydrogels with special double-network structure

Mechanically strong conducting hydrogels composed of poly(acrylamide) (PAAm) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) have been synthesized through the construction of a special double-network (sDN) structure. The novelty of the sDN hydrogels lies in the introduction of PEDOT-PSS semi-interpenetrating polymer network (semi-IPN) hydrogel as the second network. Based on the experimental results and the double-network theory, an additional strengthening effect resulting from the formation of the PEDOT clusters in a three-step fracture process is proposed. The applicability of as-prepared PAAm/PEDOT-PSS sDN hydrogels in electromechanical actuators is also briefly discussed.     

澳大利亚、新加坡交通行业职业资格建设及启示

介绍澳大利亚和新加坡在交通行业从业人员培训和考试的现状,以及相关职业资格制度的建设,对上海如何加快推进交通行业职业资格工作带来的启示。     

交流电机交叉式绕组展开图连法分析

本文介绍了嵌线方法较简便的交叉式绕组展开图的画法,并对嵌线规律及其优点进行了总结。