A model relating tool torque and its associated power and specific energy to rotation and forward speeds during friction stir welding/processing

Torque (M) is a very important quantity in the friction stir welding (FSW) process but a satisfactory model relating M to the two major FSW parameters, rotation speed (ω) and forward speed (v), has not been well developed. In this work, a better model of the form, M=f(ω, v), was sought. Experimentally, FSW of an aluminium alloy was conducted over a wide range of ω and v values and M was measured. An exponential decay function has been found to fit all the M versus ω data well and is meaningful for any ω value. The effect of v on M can approximately be accounted for through linearly relating the model parameters to v. The model allows for a detailed evaluation of the sensitivity of M to changes in ω and v. The model decay and the pre-exponential parameters need to be adjusted to make predictions for different aluminium alloys in the low ω range. Both the model and experimental data demonstrate a diminishing alloy effect on material flow resistance as ω increases. Furthermore, models of tool power (P_Tool) and specific energy (E_s) can be derived from the model for M and give predictions that are also meaningful over the entire range of ω values. Finally, the dependences of P_Tool and E_s on ω and v and the relationship between E_s and the processing zone temperature will be discussed.     

国内外己内酰胺的供需现状及发展前景

分析了国内外己内酰胺的生产消费现状及发展前景,提出了发展我国己内酰胺生产的建议。     

High response organic ultraviolet photodetector based on bis (2-methyl-8-quinolinato)-4-phenylphenolate aluminum

We report highly efficient visible-blind ultraviolet photodetectors based on 1,3,5-tris(3-methylphenyl-phenylamino)-triphenyamine (m-MTDATA) as donor and bis(2-methyl-8-quinolinato)-4-phenylphenolate aluminum (BAlq) as acceptor. Strong photoluminescence quenching of m-MTDATA by BAlq is observed manifesting the efficient photoinduced charge transfer occurs between m-MTDATA and BAlq. The optimized device exhibits a photocurrent of 172 μA/cm² at ?14 V under an illumination of 365 nm UV light irradiation with an intensity of 0.691 mW/cm², corresponding to a responsivity of 248 mA/W. We attribute the high response to the efficient electron transfer from the donor to the acceptor, the feasible level alignment match and the high carrier mobility of photoresponsive materials.     

塑料小盖注射模设计

通过对塑料小盖的工艺分析,合理地确定了模具中的浇注系统、脱模机构以及冷却系统等结构形式。并介绍了该模具的工作过程以及模具制造和装配过程中的要点。     

特产的定位路径

<正>北京的糖葫芦,涪陵的榨菜,山西的陈醋,金华的火腿,黄岩的蜜橘……这些驰名中外的特产可谓数不胜数,但都是产地品牌,而不是产品品牌。目前全国的特产有很多生产厂家,大厂、小厂、手工作坊均有,但是品牌鱼龙混杂,产品质量良莠不齐,让消费者很难辨认。一旦一个厂家出现问题,会对整个产地品牌产生伤害。2003年金华的毒火腿事件就是证明。     

电信集中结算系统高可用建设研究

本文提出了电信集中结算高可用系统的基本概念．详细介绍了集中结算系统高可用性方面的建设方案，然后对集中结算系统在某省的运行情况进行了分析。     

Juan Luis Villanueva仿真软件在S7-200 PLC教学中的应用

为了改善PLC课堂的教学效果,将Juan Luis Villanueva仿真软件用于S7-200PLC课程的日常教学。首先对Juan Luis Villanueva仿真软件做了简单介绍,之后通过实现四台电机顺序启动同时停止的例子介绍了使用仿真软件的教学过程,最后简要说明了采用仿真软件在PLC教学中的优势。     

一种新型小型化收发组件的设计

收发组件作为雷达的核心部件之一,性能好坏直接影响到雷达的整体性能。本文介绍一种Ka波段应用于雷达导引头的收发组件的基本原理,并对关键过渡形式进行重点考虑。设计出了一种小型化的收发组件,该收发组件实现一发三收的功能,具有高功率、小体积、轻重量的特点,发射通道输出功率达到了2W,接收通道增益为23d B,噪声系数为6d B,尺寸为Φ40mm×15mm,重量为95g。     

基于云原生服务网格的AI模型部署方案

人工智能模型训练完成后并不适合直接运行在互联网生产环境,需要对其进行一定的封装和部署.探讨基于容器和云原生服务网格对AI模型进行自动封装和部署,以微服务形式对外提供Restful API,能够提高模型的兼容性和部署灵活性.封装过程采用适用多框架的通用AI模型代码打包方法,解决AI模型运行环境配置问题;通过部署在云原生平...     

一种高效的MIMO-OFDM预编码实现方法

现有的预编码码本设计方法均导致了在信道量化时计算复杂度过高的问题。本文研究了Kerdock码本,这种码本由多个相互无偏基矩阵组成,这些基矩阵都只含有4个已知元素且都是归一化矩阵,并基于Kerdock码本的这种特殊结构给出了一种高效的实现方法。本文将在信道量化部分详细讲解这种实现的具体结构。这种结构有利于降低搜索复杂度,从仿真和计算结果可以看出采用这种结构的码本和量化器,能以很小的性能损失换来计算复杂度降低一半的优越性。