碳纤维自行车车架的有限元分析

利用SolidWorks软件自带的自行车车架模型,用SolidWorks Simulation软件进行模拟.设计36种不同的碳纤维铺层应用于自行车车架,根据自行车实际使用情况,分坐立、站立、行驶三种情况设置边界条件和载荷,分析讨论von Mises应力和合位移,求出碳纤维自行车车架的最佳铺层.将三种情况下测试的von ...     

自动水泥装车与堆垛设备控制系统设计

为解决目前国内袋式水泥装车与堆垛工艺仍靠人工劳动和工作环境恶劣的问题,将自动控制技术应用到水泥装车与堆垛工艺中。在充分分析研究水泥装车机与堆垛机工艺流程的基础上,利用西门子S7-200型PLC开发水泥装车与堆垛设备及其自动控制系统,进行了控制系统硬件设计及软件设计,使该设备基本实现了自动化。研究结果表明,该系统操作简单,控制可靠,维护方便,性价比高,具有较强的市场竞争力。此系统大大降低了生产过程中的人工操作,提高了生产效率及安全系数。     

四评马氏体相变的切变机制

重点解析了马氏体相变的阻力,在不考虑切变的情况下,具体计算了纯铁和铜合金的马氏体相变阻力,算得纯铁和铜合金的马氏体相变阻力分别为936 J.mol-1、36.18 J.mol-1。此马氏体相变驱动力只能用来克服切变能以外的相变阻力,推动马氏体形核长大;马氏体相变若以切变方式进行,则阻力太大,相变驱动力远远不足以完成切变。切变机制不符合省能原则。     

简述胶晶模板法制备三维有序大孔炭材料

三维有序大孔炭(3DOM)材料是近年来刚刚兴起的多孔材料领域一项重要研究课题。3DOM大孔炭材料不仅具有多孔材料的一般特点,还具有孔结构排列周期性强、孔径分布窄、大孔尺寸均匀可调,且具有较大的孔径、较高的表面积等一系列特点,在新型催化、吸附分离、电极材料等方面都具有潜在的应用价值。本文总结了近年来胶晶模板法制备三维有序大孔炭材料,分别从模板的制备、碳源的选择以及到最终大孔炭的制备三个方面加以总结概述。     

Functionalization of reduced graphene oxide nanosheets via stacking interactions with the fluorescent and water-soluble perylene bisimide-containing polymers

Reduced graphene oxide (RGO)-polymer composites were prepared via π-π stacking interactions of RGO with the perylene bisimide-containing poly(glyceryl acrylate) (PBIPGA). PBIPGA was synthesized via atom transfer radical polymerization (ATRP) of solketal acrylate (SA), using bifunctional N,N′-bis{2-[2-[(2-bromo-2-methylpropanoyl)oxy]ethoxy]ethyl}perylene-3,4,9,10-tetracarboxylic acid bisimide (PBI-Br) as the initiator, and subsequent hydrolysis of the acetal-protecting group. PBIPGA was characterized by ¹H NMR spectroscopy, gel permeation chromatography (GPC), UV-visible absorption spectroscopy and fluorescence spectroscopy. The presence of π-π stacking interactions between PBI and the RGO surface was suggested by fluorescence and UV-visible absorption spectroscopy results. The chemical states and π-π stacking interaction, morphology, and composition of RGO-PBIPGA composites were characterized, respectively, by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The low cytotoxicity level of the RGO-PBIPGA composites was revealed by incubation with 3T3 fibroblasts in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays in vitro.     

硼含量对有序态(Fe,Co)3V合金环境氢脆的影响

通过在真空和氢气环境下的拉伸实验,研究了硼含量对有序态(Fe,Co)_3V合金力学性能和环境氢脆的影响。结果表明,当在有序态(Fe,Co)_3V合金中添加0.02%B(质量分数)时,相对于无硼合金,合金的晶粒尺寸减小了27.5%,合金在真空和氢气中的抗拉强度和延伸率均达到最大值;而当硼含量继续增加时,合金的晶粒尺寸、合金在真空和氢气中的力学性能均保持不变。无硼有序态(Fe,Co)_3V合金在氢气中呈现严重的环境氢脆,当在合金中添加0.02%B后,合金氢脆因子降低了34.4%,合金的断口形貌由完全沿晶断口转变为穿晶和沿晶的混合断口;当合金中的硼含量继续增加时,合金的氢脆因子不再降低,恒定在50%左右,即硼原子只能部分抑制有序态(Fe,Co)_3V合金在氢气中的环境氢脆。     

18K黄金手镯高弹性原因分析

为研究18K黄金手镯高弹性行为,采用弹性模量测试和微观组织观察等方法对样品进行分析。结果表明,合金中存在4种相,其中3种相AuCu、AuCu_3和Au3Cu为基体无序相(Au,Cu)原子有序化后的结果,有序相的含量达到70%。有序相的大量存在可能是合金弹性模量较高的一个原因。手镯表面与截面呈现不同的弹性模量,每种相存在着一定方向的织构,可能是影响手镯弹性模量各向异性的原因。     

An Interface‐Induced Co‐Assembly Approach Towards Ordered Mesoporous Carbon/Graphene Aerogel for High‐Performance Supercapacitors

Hierarchically porous composites with mesoporous carbon wrapping around the macroporous graphene aerogel can combine the advantages of both components and are expected to show excellent performance in electrochemical energy devices. However, the fabrication of such composites is challenging due to the lack of an effective strategy to control the porosity of the mesostructured carbon layers. Here an interface‐induced co‐assembly approach towards hierarchically mesoporous carbon/graphene aerogel composites, possessing interconnected macroporous graphene networks covered by highly ordered mesoporous carbon with a diameter of ≈9.6 nm, is reported. And the orientation of the mesopores (vertical or horizontal to the surface of the composites) can be tuned by the ratio of the components. As the electrodes in supercapacitors, the resulting composites demonstrate outstanding electrochemical performances. More importantly, the synthesis strategy provides an ideal platform for hierarchically porous graphene composites with potential for energy storage and conversion applications.     

An Improved Maximum Exponentially Weighted Moving Average Control Chart for Monitoring Process Mean and Variability

Maximum exponentially weighted moving average (MaxEWMA) control charts have gained considerable attention for detecting changes in both process mean and process variability. In this paper, we propose an improved MaxEWMA control charts based on ordered ranked set sampling (ORSS) and ordered imperfect ranked set sampling (OIRSS) schemes for simultaneous detection of both increases and decreases in the process mean and/or variability, named MaxEWMA‐ORSS and MaxEWMA‐OIRSS control charts. These MaxEWMA control charts are based on the best linear unbiased estimators of location and scale parameters obtained under ORSS and OIRSS methods. Extensive Monte Carlo simulations have been used to estimate the average run length and standard deviation of run length of the proposed MaxEWMA control charts. These control charts are compared with their counterparts based on simple random sampling (SRS), that is, MaxEWMA‐SRS and MaxGWMA‐SRS control charts. The proposed MaxEWMA‐ORSS and MaxEWMA‐OIRSS control charts are able to perform better than the MaxEWMA‐SRS and MaxGWMA‐SRS control charts for detecting shifts in the process mean and dispersion. An application to real data is provided to illustrate the implementation of the proposed MaxEWMA control charts. Copyright © 2013 John Wiley & Sons, Ltd.