基于DSP技术的接触网数据采集卡的开发

针对激光雷达测距系统在接触网检测过程中所暴露出的实时性差问题,开发了基于TMS320VC5402 DSP的接触网数据采集卡,以便对由激光雷达采集的检测数据进行分析处理、信息筛选及数据传送。详细介绍了该数据采集卡的硬件构成,以及利用驱动程序开发工具WinDriver开发该采集卡的Windows驱动程序的详尽过程。     

基于改进PSO-SVM的生产线分拣机器人罐装食品识别方法

目的:解决现有食品生产线分拣机器人目标识别方法存在的准确率差和效率低等问题。方法:在对基于双目视觉食品分拣系统进行分析的基础上,提出了一种将改进的粒子群算法和支持向量机相结合用于食品分拣机器人的目标识别。通过改进粒子群算法寻优支持向量机参数,获得优化的支持向量机分类模型,对全局特征和局部特征分别进行分类器训练,动态分配特征权重系数,得到最佳识别率。通过试验分析所提方法的性能,验证其可行性。结果:与常规方法相比,所提方法在食品分拣机器人的目标识别中具有较高的识别精度和效率,准确率为99.50%,平均识别时间为0.048 s,满足机器人的分拣需要。结论:所提方法能有效识别罐装食品,提高了分拣机器人分拣准确率和效率。     

基于有限单元法的平纹织物复合材料强度预测:2.复合材料层合板拉伸过程的有限元分析

针对实际使用中平纹织物复合材料铺层角度问题,将0°/45°/90°/-45°铺层的层合板作为有限元分析对象,研究其犬骨试验件在单向拉伸作用下的响应。分析过程中,将试样视作宏观均匀的弹性材料,利用已得出的平纹织物复合材料的物性值,以8节点块单元对模型进行离散,通过分步施加载荷,得到复合材料的应力与应变曲线。与实测值作对比发现,仿真结果同实测结果相吻合。将节点反力作为复合材料单胞模型的边界条件,对复合材料进行失效预测。结果表明:角度铺层设计可以减弱细观结构的开裂和分层;且在承受相同的拉伸应力下,铺层复合材料单胞内树脂单元失效的数量少,因此具有更高的强度。     

论职业院校机械类基础课程的实践教学

职业技术学院是我国高等教育发展的产物,培养适应社会需求的实用型人才是地方职业技术学院的主要目标和任务。文章重点就如何完成好职业技术学院实践教学的教学方法、实训教材、实习实训基地管理等改革思路和方案进行了分析和探讨。并针对职业技术学院学生的特点,就机械类基础课程实践教学提出了自己的一些见解。     

ATB-25型沥青碎石基层施工实践探析

结合霍永高速公路路面施工实践经验,主要阐述了ATB-25型沥青碎石基层混合料拌制、运输、摊铺、碾压施工工艺,并对原材料、施工缝处理、平整度控制等质量关键控制要点作了论述,为确保道路工程质量提供了技术支撑。     

Highly dispersed Pt nanoparticles confined within hierarchical pores of silicalite-1 zeolite via crystal transformation of supported Pt/S-1 catalyst for partial oxidation of methane to syngas

Highly dispersed Pt nanoparticles confined within hierarchical pores of silicalite-1 zeolite were prepared via crystal transformation of supported Pt/S-1 catalyst. Selective dissolution and external recrystallization in tetrapropylammonium hydroxide solution enabled metal nanoparticles to be encapsulated in zeolites. The abundant pore structures of as-prepared Pt@S-1 catalyst were obtained by properly controlling the time of desilication and recrystallization. The properties of Pt@S-1 catalyst with hierarchical pores were characterized by XRD, ICP, SEM, TEM/HRTEM, N₂/Ar adsorption-desorption, CO adsorption, H₂-TPR and TGA techniques. Compared with the traditional supported Pt/S-1 catalyst, Pt@S-1 catalyst exhibited excellent sintering resistance, owing to the restriction of the recrystallized shell. Further, abundant pore provided access to contact with the active components, the Pt@S-1 catalyst showed excellently catalytic performance. CH₄ conversion and product selectivity were significantly improved. The out-standing catalytic performance was attributed to recrystallization of silica supported Pt. The strategy afforded enriched pore structure, improved the dispersion of active metal, and reduced the size of Pt nanoparticles. In addition, hierarchical pores of silicalite-1 zeolite supports also contributed to shorten the diffusion path of reactions.     

Effect of residual hydrogen content on the tensile properties and crack propagation behavior of a type 316 stainless steel

The tensile properties and crack propagation rate in a type 316 austenitic stainless steel prepared by vacuum induction melting method with different residual hydrogen contents (1.1–11.5 × 10⁻⁶) were systematically investigated in this research work. The room temperature tensile properties were measured under both regular tensile (12 mm/min) and slow tensile (0.01 mm/min) conditions, and the fracture properties of the tensile fractures with both rates were analyzed. It shows that the hydrogen induced plasticity loss of stainless steel strongly depends on the tensile rate. Under regular tensile condition, there is no plastic loss even when the hydrogen content is up to 11.5 × 10⁻⁶ while in the slow tensile condition, the plastic loss can be clearly identified rising with the increasing H contents. The fatigue crack propagation rate was tested at room temperature, and the crack growth rate formula (Paris) of the 316 stainless steels with varied H contents were obtained. The fatigue crack propagation rate test shows that the crack growth rate of the 316 stainless steel with 8.0–11.5 × 10⁻⁶ hydrogen is significantly higher than that of benchmark steel.     

Effect of pre-strain on hydrogen embrittlement of metastable austenitic stainless steel under different hydrogen conditions

The effects of internal hydrogen and environmental hydrogen on the hydrogen embrittlement of 304 austenitic stainless steels (ASSs) with varying degrees of pre-strain were investigated by a tensile test under cathodic hydrogen-charged, gaseous hydrogen and hydrogen-charged and gaseous hydrogen combined conditions. The internal hydrogen embrittlement of the 304 ASSs increased with increasing pre-strain, while the hydrogen embrittlement caused by the environment hydrogen increased and then decreased with increasing pre-strain. The hydrogen embrittlement mechanisms caused by the internal hydrogen or environmental hydrogen were different. The cracks caused by internal hydrogen or environmental hydrogen are mainly initiated in grain interior or at grain boundary, respectively. Under the coupling condition of internal hydrogen and environmental hydrogen, the hydrogen embrittlement of 304 ASSs was the strongest and increased with increasing pre-strain. Environmental hydrogen was dominant for low levels of pre-deformed specimens. Internal hydrogen was dominant for high levels of pre-deformed specimen.     

不同焊接工艺下2205双相不锈钢焊缝组织及性能对比

采用PAW不填丝打底焊接+TIG填丝盖面焊接、PAW不填丝打底焊+SAW盖面焊两种焊接工艺对2205双相不锈钢进行焊接,并通过力学试验、弯曲试验、金相组织观察及耐腐蚀性能试验,对焊缝的理化性能进行了检测。结果表明,两种焊接工艺焊缝的拉伸、弯曲试验结果均符合标准要求;SAW焊焊缝组织方向性较强,整体呈树枝状晶,TIG焊焊缝也存在树枝状晶,方向性较埋弧焊不明显,SAW焊热影响区组织呈连续带状分布,TIG焊热影响区组织呈间断条状分布,TIG焊母材区组织呈间断条状分布,SAW焊母材区组织呈连续带状分布;TIG焊盖面焊缝耐点蚀性能较优于SAW焊盖面焊缝耐点蚀性能。研究表明,TIG盖面焊焊缝组织及理化性能优于SAW盖面,但SAW焊生产效率比TIG焊生产效率高3倍多。可综合考虑应用工况及生产效率,选择焊接工艺。     

山西老陈醋和怀仁醋酒精发酵阶段细菌菌群多样性分析

为了探明山西老陈醋酿造工艺和怀仁醋酿造工艺对细菌菌群的影响,该研究利用高通量测序技术对两种工艺酒精发酵阶段样品（分别编号为S和X）的细菌菌群多样性进行分析。结果表明,S样品的细菌菌群多样性更高。两种工艺酒精发酵阶段样品的细菌菌群组成差别较大,与S样品相比,X样品中相对丰度较高的乳杆菌属（Lactobacillus）、魏斯氏菌属（Weissella）、乳球菌属（Lactococcus）均增多,片球菌属（Pediococcus）、明串珠菌属（Leuconostoc）、泛菌属（Pantoea）、链霉菌属（Streptomyces）、短状杆菌属（Brachybacterium）、肠杆菌属（Enterobacter）和非培养细菌（uncultured bacterium）均减少。导致两种工艺酒精发酵阶段样品有显著差异的细菌在S样品中为片球菌属、明串珠菌属、链霉菌属和泛菌属,在X样品中则为乳杆菌属、魏斯氏菌属和乳球菌属。相关性分析结果表明,乳杆菌属、泛菌属、魏斯氏菌属和片球菌属与其他物种联系紧密。