管座焊缝内侧的相控阵超声自动检测

本文介绍应用相控阵技术结合配有编码动作的机械装置,对插入式管座焊缝从接管内侧用线阵探头进行超声检测的方法。建立实验模型,可为声柬全覆盖所必须考虑的物理参数,提供验证数据。建模和实测结果表明：利用声线跟踪法,扫查布置图（Scanplan）能提供所需覆盖范围的适当显示。当从接管内表面进行扫查时,用于引导探头扫查动作的机械装置往往可设计得减少复杂性。本文所述方法可望为承压设备结构较复杂的管座焊缝,实施超声相控阵检测（PAUT）符合ASME最新版要求提供有用借鉴。     

基于ADAMS/Rail的直线电机轨道交通安全性研究

阐述了直线电机轨道交通的技术特点,并就其安全评价体系做了介绍,应用ADAMS/Rail软件分别建立了轮对、构架、悬挂系统、止挡、自导向径向转向架、直线电机以及车体的模型,并考虑轮轨关系组合为直线电机轨道交通的车辆-轨道耦合动力学整体模型,进行了大量的计算仿真。笔者主要以脱轨系数为例进行了动力响应分析,给出考虑了径向转向架和直线电机后的安全评判指标,比较了与径向转向架和未安装直线电机的区别,验证了模型的正确性和有效性。为后续研究直线电机轨道交通车辆-轨道耦合动力学模型提供了理论基础,从而可以进一步从安全性角度研究线路设计参数。为我国今后直线电机轨道交通建设就线路参数对车辆运行安全性的影响研究方面起到理论指导作用。     

Injection Molded Wheat Straw and Corn Stem Filled Polypropylene Composites

Environmentally friendly composite materials can be prepared using wood fibers and/or various types of agro-derived fibers as reinforcements. In this study, agro-residues such as wheat straw and corn stem filled polypropylene were prepared and their suitability was investigated as a reinforcing filler in thermoplastics and as an alternative to the wood flour filled plastics. Effect of compounding techniques, compatibilizer and fungal treatment of agro-residues on the mechanical properties of the composites were evaluated. It was found that high shear compounding of wheat straw fibers exhibited similar properties to that produced by the milled wheat straw. This may be due to the extensive fiber breakage occurred during the high shear compounding that results in a similar aspect ratio to that of milled straw. Compatibilizer is needed for improving the strength properties of the agro-residue filled PP composites. Fungal treatment of milled wheat straw did not show much improvement in the strength properties of the composites. Comparison of mechanical properties of the agro-residue filled PP with that of the wood flour and the old newsprint filled PP showed the suitability of the agro-residues as alternative filler for thermoplastics.     

铁路隧道整体式衬砌火灾力学响应特性数值模拟

通过ANSYS有限元数值模拟软件,建立了铁路隧道整体式衬砌的二维热力耦合有限元计算模型,基于ISO834标准火灾温升曲线,对不同单双线和不同等级围岩的铁路隧道整体式衬砌(单线III级围岩衬砌、双线III级围岩衬砌、单线IV级围岩衬砌、双线IV围岩衬砌)的火灾力学响应行为进行了数值模拟研究,获得了火灾作用下,不同的铁路隧道整体式衬砌拱顶竖向位移、边墙侧向位移、压应力、剪切应力的变化情况。结果表明:双线整体式衬砌拱顶的竖向位移大于单线整体式衬砌,围岩等级越大整体式衬砌拱顶的竖向位移越大,整体式衬砌承受的最大压应力和最大剪切应力随时间集中在不同厚度层的混凝土区域上。所获得的结论可为铁路隧道整体式衬砌的防火设计和安全性研究提供理论参考。     

抗醇泡沫灭火剂在水溶性有机溶剂表面铺展能力的实验研究

为了研究抗醇泡沫灭火剂在水溶性有机溶剂表面的铺展能力,发明了一种新的实验方法,正交实验了9种配方。得到了粘度、发泡倍数和表面张力对铺展能力的影响数据,通过方差分析验证了数据的可靠性。研究发现抗醇泡沫灭火剂的粘度和发泡倍数可以影响其在醇类表面的铺展能力,但是表面张力对铺展无影响。对于泡沫的铺展存在一个最佳粘度和最差发泡倍数。扩散系数不能表征抗醇泡沫灭火剂在水溶性有机溶剂表面的铺展能力。     

Experimental investigation of the pressure gradient of a new spiral mesh foam generator

Foam is used as part of an effective dust suppression method in underground coal mines, but conventional foaming devices severely restrict its popularization and application due to the high cost of foam preparation, poor applicability and high pressure loss. Therefore, a new spiral mesh foam generator is designed, and its performance is investigated and evaluated experimentally. The results show that the pressure gradient of the spiral mesh foam generator increases with the increase of foam concentration in water. There is a large pressure gradient gap between the top and bottom at both ends of the foam generator. However, the gap disappears and uniform foam is generated in the middle section of the foam generator. When the pressure gradient is higher than minimum pressure gradient, the foam production quantity will increase sharply. Based on the length of spiral mesh and operating conditions determined, the new foam generator is applied to produce foam for dust suppression in the heading face of coal mines. A good foaming effect, less pressure loss and high dust suppression efficiency suggest that the new foam generator will greatly promote the large-scale application of foam technology used to suppress dust in underground coal mines.     

The effect of Mg(BH4)2 on the energy characteristics of RDX based aluminized explosives

This paper mainly discusses the effect of Mg(BH₄)₂ on RDX-based aluminized explosives' energy characteristics. RDX/Mg(BH₄)₂, RDX/Al/Mg(BH₄)₂, RDX/AP/Al/Mg(BH₄)₂ mixed explosives were prepared by molding power method. The influence of energy storage materials on the performance of mixed explosives was discussed by adjusting the proportion of Mg(BH₄)₂. The impact sensitivity, friction sensitivity, detonation heat experiment, and XPS experiment were carried out for the mixed explosive. The mechanical sensitivity, energy characteristics, and the products after the explosion of the mixed explosive were analyzed. Through the above experiments, it is concluded that Mg(BH₄)₂ can effectively improve the energy characteristics of RDX, but its safety will become worse after being prepared by a simple mixing method, and the use of the molding power method can effectively reduce the sensitivity. As the mass fraction of Mg(BH₄)₂ increases and Al decreases, the detonation heat of explosives decreases gradually. Mg(BH₄)₂ made the oxygen balance of mixed explosives more negative has been considered as a potential reason. Analysis of the detonation heat solid products by XPS found that, unlike our expected results, the product contained a large amount of low calorific value of B₂O₂ instead of B₂O₃, which may be a crucial reason. This paper provides a reference for the application of Mg(BH₄)₂ in energetic materials and is of great significance for the development and application of new materials in energetic materials.     

石家庄某机械制造企业搬迁遗留土壤调查及污染成因分析

以石家庄某机械制造企业搬迁遗留场地为例,结合分区与专业判断进行土壤调查与分析。结果表明:27个点位不同深度土壤样品中,氰化物、六价铬及多氯联苯均未检出。检出重金属6种,总石油烃2种、苯系物3种,但均未超标。污染主要来源是原辅材料堆存和在工艺过程中遗撒、泄漏迁移所致。     

水成膜泡沫对变压器油池火的窒息特性研究

水成膜泡沫在油类表面的窒息作用是扑灭油类火灾的重要机理之一,针对自行开发的快速型泡沫灭火剂开展了其对油池火的窒息灭火特性研究。首先通过老化试验测试了泡沫液的热稳定性,然后对比了不同成分泡沫液在25#变压器油表面的铺展特性,之后研究了不同发泡倍率和成分的泡沫液对油池火的窒息灭火效果及影响规律。研究发现,铺展性能不佳的泡沫液会逐渐丧失窒息能力,而铺展性能优异的泡沫液能持续发挥窒息作用。提升泡沫液热稳定性有利于在油面形成稳定的液膜,隔绝氧气并降低可燃分子挥发速率。此外,发泡倍率较低的泡沫液的流动性更强,在相同液体流量条件下低倍数泡沫的窒息灭火效果更优。自研的快速型泡沫灭火剂在热稳定性和铺展性能两方面均具备优良的性能,因此其窒息灭火效率和抗复燃能力优于现有的大部分同类泡沫灭火剂。     

新型难燃隔热保温材料——酚醛泡沫

本文介绍了一种新型难燃隔热保温材料-酚醛泡沫塑料,它具有有机泡沫保温材料低热导率的优异性能,也具有无机保温材料优异的防火性能.