基于线上线下混合式大班翻转的单片机教学改革

在电子行业迅速发展的背景下,单片机课程对学生的作用越来越重要,然而学生对单片机课程不容易学会并且没兴趣学,把自己当做观众不全力学,导致学生掌握的课程内容跟不上时代发展的步伐。提出了线上线下混合式大班翻转的教学改革思路,将线上自主学习和线下翻转教学相结合,学生通过网络平台自主学习基本理论;知识延伸部分以翻转课堂的形式在多媒体教室进行。使学生有针对性的学习,提高了学习单片机知识的积极性,通过师生取得的成果证明了该教学改革取得了一定的效果。     

钽钛合金再结晶退火工艺研究

研究了二元钽钛合金丝经拉拔加工中间再结晶退火处理后的组织。结果发现:变形量为12%的!1.5mm的钛钽合金丝经1000℃×1h退火能够发生完全再结晶;变形量由17%增大至70%,再结晶温度下降约40℃,变形量对再结晶温度影响较大;变形量越大,再结晶后的组织晶粒细小。     

Similar simulation study on the deformation and failure of surrounding rock of a large section chamber group under dynamic loading

Large and super-large section chamber groups in coal mines are frequently affected by dynamic loads resulting from production activities such as roadway driving and blasting. The stability of the surrounding rock is poor, and it is difficult to control. In this paper, a similar simulation test was used to study the deformation and evolution laws of the surrounding rock of a triangle-shaped chamber group under different dynamic loads. The results showed that under dynamic loading, the vertical stress of the surrounding rock of the chamber group increased in an oscillatory form. The maximum stress concentration coefficient reached 4.09. The damage degree of the roof was greater than that of the two sides. The deformation of the roof was approximately 1.2 times that of the two sides. For the chamber closer to the power source, the stress oscillation amplitude of the surrounding rock was larger, and the failure was more serious. The force of the anchorage structure showed a phased increasing characteristic; additionally, the force of the anchorage structure on the adjacent side of the chambers was greater than that on the other side. This study reveals the deformation and failure evolution laws of the surrounding rock of large section chamber groups under dynamic loading.     

铜冶炼企业产品质量控制的探索与实践

为了保持阴极铜化学成分和质量长期稳定,某铜冶炼企业对阴极铜化学成分进行监控,对铜冶炼生产系统中电解工序物料、产出后又重回本系统物料、贵金属系统中产出物料、外购原料中物料的杂质总量进行分析,提出了减少杂质对阴极铜质量影响的措施,为阴极铜质量的稳定创造了良好的生产条件,并提升了企业适应复杂原料市场的能力。     

用实型铸造方法生产42 t磨床床身

我公司采用实型铸造方法,铸造了毛坯质量达42t的大型磨床床身。用冷硬呋喃树脂砂造型、导轨部位加外冷铁、合理布置排气口等方法,成功铸造出了磨床床身。经检测,铸件几何尺寸、力学性能、化学成分、导轨硬度均达到图纸的技术要求,为铸造生产大型和特大型铸铁机床床身提供了经验。     

改善烧结法碳酸化分解产品质量的措施

本文简要阐述了提高氧化铝质量的必要性和紧迫性，并从烧结法碳酸化分解工艺着手，简介了碳酸化分解的工艺过程，同时从理论上分析了铝酸钠溶液碳酸化分解过程的变化规律，结合影响碳酸化分解产品质量的多种因素的试验结果，提出了碳分分解温度、分解时间、晶种特性和晶种添加量等是影响碳分产品质量的重要因素。     

水量对锐钛矿溶胶制备、结构及光催化性能的影响

选择“钛酸丁酯-水-乙醇-盐酸”的溶胶．凝胶反应体系，考察反应物水的用量变化对反应过程、溶胶结构和光催化性能的影响，并获得了含有锐钛矿晶体、具有光催化性能的氧化钛溶胶。钛酸丁酯与水的摩尔比为1：2、1：4、1：8时，会逐渐形成凝胶，溶胶常温干燥后的粉体呈无定型结构，透射电镜中只能观察到细小的成膜粒子，溶胶不能使罗丹明B溶液分解褪色。钛酸丁酯与水的摩尔比为1：40、1：100、1：200时，钛酸丁酯发生充分水解，有可能形成稳定的溶胶；溶胶常温干燥后的粉体呈锐钛矿晶型，且结晶强度随水的用量的增加而增强；透射电镜中可观察到松散的团聚体、初显正方形较为紧密的结晶体和致密规则的正方形锐钛矿晶体；各溶胶均可催化降解罗丹明B使其褪色。     

多通管塑挤胀形工艺的力学分析

讨论了以聚氨酯橡胶棒为胀形介质，采用塑挤胀形复合工艺把无缝管坯一次成形为多通管成品的加工方法，分析了多通管塑挤胀形过程，提出了“应变样条”分析法，进而分析了典型剖面上应力应变状态，讨论了成形力间应具备的合理的数值关系，以使变形区处于最有利于变形的超高的静水压力和合适的偏应力状态，获得尽可能长的支管。     

Tool design in a multi-stage drawing and ironing process of a rectangular cup with a large aspect ratio using finite element analysis

Tool design is carried out for a multi-stage deep drawing and ironing process of a rectangular cup with the large aspect ratio using the result of the finite element analysis. The analysis incorporates three-dimensional continuum elements for an elasto-plastic finite element method with the explicit time integration scheme using LS-DYNA3D. The analysis simulates the five-stage deep drawing and ironing process with the thickness control of the cup wall. Simulation is performed in order to investigate the failure by tearing during the forming process at the initial state of tool design. The analysis reveals that the difference of the drawing ratio within the cross section induces non-uniform metal flow which causes severe local extension. The irregular contact condition between the blank and the die also induces non-uniform metal flow which causes local wrinkling. This paper identifies such unfavorable mechanism in the rectangular cup drawing with ironing and proposes a new tool design with the guideline for modification in the design of the process and the sequential tool shape. The finite element analysis result with the improved tool design confirms that the proposed design not only reduces the possibility of failure but also improves the quality of a deep-drawn product. The numerical result shows fair coincidence with the experimental result.     

液压支架高压大流量阀综合试验台设计与仿真北大核心

针对液压支架高压大流量阀设计以双蓄能器组为辅助动力源的试验台,配合增压缸实现系统的分时快速加载。该试验台可为被试阀提供近乎阶跃的短时大流量高压冲击,模拟液压支架承受严重顶板冲击的工况。基于AMESim软件搭建试验系统的仿真模型,并以FAD100/40型安全阀为试验对象,进行冲击压力安全性和公称流量启溢闭特性仿真分析。结果表明:所设计的安全阀冲击安全性试验系统能在规定时间内达到国家标准规定的阀前冲击压力;公称流量启溢闭特性试验系统提供的被试阀开启压力、流量、压力上升梯度及公称流量溢流时间均满足国家标准,进一步验证了试验台及试验方法的合理性。