铁路动车组快餐盒饭微生物检测结果分析

目的了解铁路动车组快餐盒饭的微生物污染现状,保证旅客的食品安全。方法按照危害分析和关键控制点（HACCP）的原理及国际食品法典委员会（CAC）文件管理方法的要求,对动车组食品原料、半成品、成品、环境、设备、人员等控制对象的微生物指标进行检测。结果抽查样品共计150份,对其加工过程进行危害分析,将原料储存、烹调加热、成品储存、餐具消毒确立为关键控制点。结论快餐盒饭按HACCP计划实施3个月来,效果良好,为盒饭的安全控制提供参考。     

管内站车食品"索证" 调查与分析

为保障旅客旅行中的饮食安全 ,杜绝食物中毒的发生 ,按有关规定我们于 5年前在管内站车食品生产经营单位开展了食品“索证”工作 ,即采用向进站上车销售食品的经销商索取食品卫生许可证和检验报告单、办理“认可证”的方法 ,杜绝假冒伪劣食品入路销售。通过实施办理“认可证”制度 ,几年来 ,食品生产经营单位食品“索证”率由实行前的 37%提高到现在的 79 5 %,辖区内站车食品卫生监督管理更加规范 ,进站上车食品货主主动办理“入路认可证”已成共识 ,假冒伪劣食品很难进入辖区站车单位销售 ,站车食品卫生管理得到明显加强 ,有力地保障了旅客…     

Effect of remelting current on molten pool profile of titanium alloy ingot during vacuum arc remelting process

The performance of vacuum arc remelting (VAR) ingot depends largely on ingot structure and chemical uniformity, which are strongly influenced by molten pool profile that is influenced by VAR process. To better understand the effect of remelting current on molten pool profile of titanium alloy ingot during VAR process, a 3D finite element model is developed by the ANSYS software. The results show that there are three remelting stages during VAR process when the remelting current is 2.0 kA. The molten pool depth increases gradually from 30 to 320 s, then the change of molten pool depth is very small during the steady state stage from 320 to 386 s, and lastly the molten pool depth becomes shallow after 386 s. The melting rate and temperature of superheat increase with the remelting current increasing, which leads to the augment of molten pool volume. In the end, the total remelting time and steady state molten pool time decrease with the melting current from 1.6 to 2.8 kA.     

Numerical analysis of material properties in deformation of near hemispherical shells

In this paper, the effects of hardening exponent, yield strength and elastic modulus on the deformability of near hemispherical shells are investigated by means of finite element method and orthogonal experiment design. The largest eccentric angle during the deformation process and thickness reduction after the deformation are introduced to estimate the deformability quantitatively according to the deformation characteristics of near hemispherical shells. The results indicate that the hardening exponent is the most influential parameter, followed by elastic modulus and yield strength. The shell exhibits good deformability when the hardening exponent and elastic modulus are in the range of 0.1–0.125 and 70–108 GPa, respectively.     

基于三维软件的虚拟装配技术应用

本文结合三维设计软件在实际工作中的运用，通过虚拟装配，在设计过程中发现并解决零件装配过程中的相互干涉、功能实现等问题。同时，使用虚拟装配，可以准确判定零件制造过程中出现的超差零件能否采用。采用虚拟装配，可在很大程度上降低科研设计成本，节约生产成本，提高生产力。     

基于神经网络PID控制的客车ECAS设计与实现

以飞思卡尔MC9S08GB60单片机为控制核心,以亚星YBL6891H型客车为试验对象,针对空气悬架系统本身的非线性特性,采用神经PID控制算法,设计了一种通过检测车身高度对空气弹簧进行充排气,进而改变弹簧刚度的客车电控空气悬架系统.根据悬架评价指标建立了电控悬架的2自由度1/4车辆模型,通过仿真验证了该悬架系统对悬架动行程、车轮动载荷及车身垂直加速度这3项汽车行驶平顺性评价指标的改善,最后通过试验验证了所设计控制策略的正确性.