一种利用负压吸动效应的动态配气方法

为使难挥发性液态气源更好地挥发制取标准气体,提出一种利用负压吸动效应的雾化配气法。设计了结构精密的雾化发生池,用实验的方法确定影响发生池负压值的各种参数,在实际应用中达到良好的效果。利用三种方法对难挥发的液态气源进行配气实验,雾化法与另外两种常用的方法相比,效果更好。     

新型撞击式气液两相喷嘴雾化特性的研究

针对卷烟厂实际生产需要,对气水混合喷雾加湿系统的关键部件--喷嘴进行优化设计,研制出了一种新型的撞击式气液两相喷嘴.通过喷嘴雾化特性实验,详细讨论了气压、水压对雾滴粒径大小的影响,以及不同水压下的气、液消耗量.实验得出,气液压差为0.1 MPa时雾化技术经济效果最佳.     

气-水雾化喷嘴特性实验研究

为解决冷却器换热效率低的问题,提出将气-水雾化喷嘴应用于间接蒸发冷却,实验研究间接蒸发冷却器专用扇形气-水两相雾化喷嘴的特性,获得不同压力时喷嘴的雾化角和气水流量值及其变化规律,确定出最佳的喷雾气水比和雾化角等特性参数。     

气-水雾化喷嘴特性实验研究

为解决冷却器换热效率低的问题,提出将气一水雾化喷嘴应用于间接蒸发冷却,实验研究间接蒸发冷却器专用扇形气-水两相雾化喷嘴的特性,获得不同压力时喷嘴的雾化角和气水流量值及其变化规律,确定出最佳的喷雾气水比和雾化角等特性参数。     

原子吸收分光光度计气路及雾化系统的日常维护与维修

原子吸收分光光度计属于大型精密计量仪器,广泛应用于化工、环保、水文等各个领域。我们在从事光谱仪器计量检定工作中经常遇到原子吸收分光光度计由于气路及雾化系统的故障而影响仪器使用的问题,本文简要介绍气路及雾化系统发生故障的原因及排除的方法,供原子吸收分光光度计的保管者及使用者参考。１气路系统的维护与维修气路系统由燃气及助燃气供气装置及通气管道构成。燃气供气装置一般为燃气钢瓶,助燃气供气装置一般为空气压缩机。日常工作中对气路系统应做下列的维护保养工作。（１）定期检查管道、阀门接头等各部分是否漏气,如…     

基于决策树算法的多联机气液分离器插反故障诊断

本文将决策树算法应用于多联机气分插反故障诊断中,搭建了多联机实验平台采集数据,根据专家知识及数据变化模型验证选取了建模的特征变量,采用决策树C5.0算法构建气分插反故障诊断模型,进一步对由模型分类规则生成的最优变量即过冷器的EEV(电子膨胀阀)进行深入分析和验证。结果表明:将决策树算法应用于多联机气分插反故障诊断的方法,准确率为96%,此诊断方法能满足多联机故障诊断实际运用的需要,并可及时处理多联机发生气分插反故障时,系统过热度降低,从而保证多联机系统的制冷效果和能效比,可通过增大过冷器EEV开度调节。     

基于决策树算法的多联机气分插反故障诊断

本文将决策树算法应用于多联机气分插反故障诊断中,搭建了多联机实验平台采集数据,根据专家知识及数据变化模型验证选取了建模的特征变量,采用决策树C5.0算法构建气分插反故障诊断模型,进一步对由模型分类规则生成的最优变量即过冷器的EEV（电子膨胀阀）进行深入分析和验证。结果表明：将决策树算法应用于多联机气分插反故障诊断的方法,准确率为96%,有较高的准确性和可靠性,此诊断方法能满足多联机故障诊断实际运用的需要。由于多联机发生气分插反故障时,系统过热度降低,为保证多联机系统的制冷效果和能效比,可通过增大过冷器EXV开度调节。     

CS600高频红外碳硫分析仪的维护

一、碳硫分析仪的气路检漏与检修1.碳硫分析仪的气路检漏仪器气路检漏分为系统检漏与分段检漏两种方式。系统检漏:从载气入口的SV6至尾部的SV8电磁阀(见图1),载气在气路中充气超过外界大气压并达到159.9868k Pa(1200mm Hg)后,SV6与SV8封闭内部与外部的连接,在1min内气体泄漏量不超过规定数值即为通过。分段检漏:包括试剂部位、气标部位、炉头部位和检测池部位气路的检漏。     

基于激光粒度仪测量油品喷雾粒径的方法研究

为了测量油品喷雾过程的雾化性能,通过对喷嘴雾化粒径的指标和雾化粒径测定方法的分析,利用激光粒度仪及粒径发生装置设计喷嘴雾化实验系统,并对实验系统的工作原理进行描述;在不同喷雾压力下测定煤基柴油特征平均粒径dv10、dv50、dv90、d[3,2]、d[4,3]数据。结果表明:柴油雾化过程分为形成阶段、扩散阶段、稳定阶段;喷雾压力越大,雾滴特征平均粒径dv10、dv50、dv90、d[3,2]、d[4,3]参数值越小,雾化效果越好,并且随着喷雾压力的增大,液滴雾化粒径减小的趋势变缓。     

新型节能摩托车发动机燃油系统改造

纳米雾化在发动机节能减排中的应用研究，主要为现今市场上摩托车发动机提供一个更加节能环保的燃料供给系统，利用超声波高频振荡的原理，将汽油雾化成直径约2μm的粒子，然后将深度雾化的汽油雾粒与空气完全混合，形成比较好的混合气，节能燃油系统根据不同的摩托车运行工况，调节摩托车节气门的开度，与新鲜空气混合，形成比较理想的空燃比。     

基于机器学习的薄板等离子弧搭接焊的熔深预测

在等离子弧搭接焊中,搭接焊接头的焊缝熔深是评价焊接质量的关键指标之一,而焊接过程中的热输入信息和熔池图像信息都与焊缝熔深有密切关系。本文通过建立304L不锈钢薄板等离子弧搭接焊数据采集系统,利用LabVIEW实时检测电信息,采用视觉传感技术实时获取薄板等离子弧搭接焊过程中的熔池图像,并通过图像处理方法获得熔池的几何参数信息,结合焊接工艺参数,选择峰值电流、峰值电压、焊接速度、离子气流量、保护气流量、熔池宽度和熔池后端长度作为输入量,焊缝熔深作为输出量,建立了基于支持向量机回归和BP神经网络的熔深预测模型。实验验证表明,采用径向基函数的支持向量机回归模型可以有效地对焊缝熔深进行预测,并具有很好的泛化能力,可为进一步实现在线优化焊接工艺参数提供依据。     

标样气体进样系统

标样气体进样系统用于质谱计的标样气体校准 ,以获得准确的测量数据。介绍了标样气体进样系统的结构、工作原理及进样方法 ,给出了标样气体配置的不确定度分析和测试结果。     

Influence of gravity state upon bubble flow in the deep penetration molten pool of vacuum electron beam welding

The governing equations of two-dimensional bubble flow model for gas–liquid two-phase system in deep penetration molten pool of vacuum electron beam welding were developed according to the laws of mass and momentum conservation. The separation models of gas and liquid convections in bubble flow were formed by regarding the gas phase in molten pool as a particle phase, and the vacuolar fraction, velocity slip, pressure gradient and other factors were introduced into the models. The influences of the gravity state upon the convection of bubble flow and the distribution of cavity-type defects in molten pool of AZ91D magnesium alloy were studied by the method of numerical simulation based on the mathematical models. The results showed that the gravity is an important factor to drive the convection of the bubble flow in the deep penetration molten pool during vacuum electron beam welding. The gravity has an impact on the gas distribution in molten pool, thus affects the distribution of cavity-type defects in weld. Because of the gravity contributing to driving the convection of bubble flow, it is conducive to the escape of gas phase in molten pool and reducing the air rate. A larger convection velocity of gas phase is helpful to the escape of gas phase, thus reduce the tendency of cavity-type defects.     

食品添加剂二氧化碳中苯气体标准物质性能评价方法的研究

介绍了食品添加剂二氧化碳中苯气体标准物质的分析方法和性能评价方法。采用美国Agilent6890N气相色谱仪、FID检测器,在最佳色谱实验条件下对苯的检测限小于10×10^-9,线性误差小于2%。还给出了二氧化碳中苯气体标准物质均匀性、一致性、稳定性（随时间、压力变化）的考察结果。研究成果表明二氧化碳中苯气体标准物质重量配制的相对扩展不确定度小于1.7%。     

Role of arc mode in laser-metal active gas arc hybrid welding of mild steel

Arc mode plays an important role in joint characterizations of arc welding, but it has been seldom considered in laser-arc hybrid welding. This paper investigated the role of arc mode on laser-metal active gas (MAG) arc hybrid welding of mild steel. Three arc modes were employed, which were cold metal transfer (CMT), pulsed spray arc and standard short circuiting arc. Microtexture of the joints were observed and measured via electron back scattering diffraction (EBSD) system to reveal the effect of arc mode on microstructure. Mechanical properties of the joints were evaluated by tensile and Charpy V-notch impact tests. It was found that both the stability and mechanical properties of laser-CMT hybrid welding (LCHW) is the best, while those of laser-standard short circuiting arc welding (LSHW) is the worst. OM and EBSD results showed that the fraction of acicular ferrite and high-angle grain boundaries in fusion zone decreases gradually in the sequence of LCHW, laser-pulsed spray arc welding and LSHW, while the mean grain size increases gradually. Finally, the microstructure formation mechanisms and the relationship between microstructure and mechanical properties were summarized by the loss of alloying element and the stirring effect in molten pool.     

Bubble flow and the formation of cavity defect in weld pool of vacuum electron beam welding

Seen from gas-liquid two-phase-flow system, the gas phase and liquid phase of bubble flow in weld pool are studied by means of isolated phase based on the conservation of mass and momentum. The two-dimensional fractional flow model of bubble flow in weld pool of vacuum electron beam welding is developed. And the gas distribution and the phenomenon of bubble flow in weld pool of AZ91D magnesium alloy are simulated to analyze the formation and distribution of cavity defects. The results show that the possibility of gas escape in fully penetrated weld pool is much greater than non-penetrated weld. It appears that the probability of cavity defects is lower than non-penetrated weld to some extent. The formation of typical cavity defects is closely related to the flow pattern and flow characteristics of the bubble flow in deep penetration weld pool of vacuum electron beam welding. Higher liquid flow rate is more conducive to the escape of gas in molten metal, so that the final porosity in weld is low.     

Bubble flow and the formation of cavity defect in weld pool of vacuum electron beam welding

Seen from gas-liquid two-phase-flow system, the gas phase and liquid phase of bubble flow in weld pool are studied by means of isolated phase based on the conservation of mass and momentum. The two-dimensional fractional flow model of bubble flow in weld pool of vacuum electron beam welding is developed. And the gas distribution and the phenomenon of bubble flow in weld pool of AZ91D magnesium alloy are simulated to analyze the formation and distribution of cavity defects. The results show that the possibility of gas escape in fully penetrated weld pool is much greater than non-penetrated weld. It appears that the probability of cavity defects is lower than non-penetrated weld to some extent. The formation of typical cavity defects is closely related to the flow pattern and flow characteristics of the bubble flow in deep penetration weld pool of vacuum electron beam welding. Higher liquid flow rate is more conducive to the escape of gas in molten metal, so that the final porosity in weld is low.     

可移动式多通道带吹扫微量氧分析仪检定装置的研究

文章叙述了多通道带吹扫微量氧分析仪检定试验装置的研究,该装置由标气储存系统、压力控制系统、管路切换系统和流量控制系统组成。最多可以接入八瓶不同浓度的微量氧标准气体,装置全部采用不锈钢内抛光气体管路,避免了在传统检定过程中环境空气的混入,提高工作效率并大幅减少标准气消耗。装置带有转向轮,将气瓶固定,并且可以根据实际需要将装置进行移动。     

pVTt法气体流量标准装置开关阀时间系统差补偿方法

针对pVTt法气体流量标准装置中开关阀影响喷嘴流出系数的测量结果的问题,分析了pVTt法气体流量标准装置中高真空蝶阀和高真空球阀的流通面积与开度的关系,分别推导了2种阀门的质量流量随时间变化的计算公式, 并计算了2种阀门最佳的计时位置。 设计了一套实验装置对2种阀门最佳的计时位置进行了验证, 结果表明:所用蝶阀和球阀的最佳计时点分别位于阀门打开4.5°和2.5°的位置。     

Study on welding process and prosperities of AA5754 Al-alloy welded by double pulsed gas metal arc welding

In this paper, the effect of double pulsed gas metal arc welding (DP-GMAW) on metal droplet transfer, weld pool profile, weld bead geometry and weld joint mechanical properties of Al alloy AA5754 are presented. A high speed camera was utilized to reveal the metal transfer behavior and weld pool profile. A self-developed electrical signal acquire system was adopted to record the current waveform during welding process. The results indicated that the metal transfer, weld pool profile and weld bead geometry in DP-GMAW significantly differ with P-GMAW. The microstructure showed that grain size of the weld bead decreased with increasing of thermal pulse frequency, and the eutectic precipitates Mg₂Si were homogeneously distributed at fusion zone. The mechanical properties of welded joints were improved.