Experimental study on the feasibility of explosion suppression by vacuum chambers

In view of the invalidity of suppression and isolation apparatus for gas explosion, a closed vacuum chamber structure for explosion suppression with a fragile plane was designed on the base of the suction of vacuum. Using methane as combustible gas, a series of experiments on gas explosion were carried out to check the feasibility of the vacuum chamber suppressing explosion by changing methane concentration and geometric structure of the vacuum chamber. When the vacuum chamber was not connected to the tunnel, detonation would happen in the tunnel at methane volume fraction from 9.3% to 11.5%, with flame propagation velocity exceeding 2000 m/s, maximum peak value overpressure reaching 0.7 MPa, and specific impulse of shock wave running up to 20 kPa s. When the vacuum chamber with 5/34 of the tunnel volume was connected to the flank of the tunnel, gas explosion of the same concentration would greatly weaken with flame propagation velocity declining to about 200 m/s, the quenching distance decreasing to 3/4 of the tunnel length, maximum peak value overpressure running down to 0.1-0.15 MPa and specific impulse of shock wave below 0.9 kPa s. The closer the position accessed to the ignition end, the greater explosion intensity weakened. There was no significant difference between larger section and smaller vacuum chambers in degree of maximum peak value overpressure and specific impulse declining, except that quenching fire effect of the former was superior to the latter. The distance of fire quenching could be improved by increasing the number of the vacuum chambers.     

实用视频干扰抑制器研制探讨

视频干扰是电视监控工程中最为头痛的事,如何抑制或解除干扰？针对这一问题,笔者和同事们进行了“实用视频干扰抑制器”的研究与开发工作。历经两年时间,在受到不同性质干扰的电视监控工程（电梯、石化、医院、电信、铁路、电台和电力等）中实地反复试验测试，找出解除干扰的办法,应用研发的“实用视频干扰抑制器”解除了这些电视监控工程中图像受到的干扰。     

Environmental and economic assessment of combined biostabilization and landfill for municipal solid waste

Biostabilization can remove considerable amounts of moisture and degradable organic materials from municipal solid waste (MSW), and can therefore be an effective form of pretreatment prior to landfill. The environmental and economic impacts of two combined processes, active stage biostabilization + sanitary landfill (AL), and active and curing stage biostabilization + sanitary landfill (ACL), were compared with sanitary landfill (SL) for MSW with high moisture content. The results indicated that land requirement, leachate generation, and CH(4) emission in the ACL process decreased by 68.6%, 89.1%, and 87.6%, respectively, and the total cost was reduced by 24.1%, compared with SL. This implies that a combined biostabilization and landfill process can be an environmentally friendly and economically feasible alternative to landfill of raw MSW with high moisture content. Sensitivity analysis revealed that treatment capacity and construction costs of biostabilization and the oxidation factor of CH(4) significantly influenced the costs and benefits of the AL and ACL process at an extremely low land price. When the land price was greater than 100 USD m(-2), it became the dominating factor in determining the cost of treatment and disposal, and the total costs of ACL were reduced to less than 40% of those of SL.     

油田冲砂清洁生产工艺的研究应用

针对传统的油井清砂方法易产生环境污染的现状,胜利采油厂对油田修井冲砂工艺进行了改进,通过改装设备;改进捞砂工艺等措施,自2000年1月至2001年11月,已经实施捞砂作业井417口,一次成功井373口,一次成功率为89.45%。工艺改进实施后,还节省了化学堵剂的使用;杜绝了油层污染;减轻了现场操作人员的劳动强度和冲砂事故发生率,初步实现了油田修井冲砂施工的清洁生产。     

Study on machinability of a stellite alloy with uncoated and coated carbide tools in turning

Stellite alloys, which have been widely used in the aerospace, automotive and chemical industries, are hard-to-cut cobalt-based materials. This study investigates the machinability of stellite 12 alloys with uncoated carbide cutting tool grades YG610 (K01-K10) and YT726 (K05-K10/M20) and SANDVIK coated carbide tool SNMG150612-SM1105 under dry cutting conditions. Both wear mechanisms and failure modes of the uncoated and coated tools were investigated with turning experiments. The results show that the coated tool SM1105 remarkably outperforms the uncoated tools; and the cutting tool YG610 generally outperforms YT726 under all cutting conditions. Built-up edge was found with YG610 in some cutting conditions and with SM1105 at cutting speed of 16 m/min. Tool surface burning marks were observed on YT726 at relatively higher cutting speeds. Wear develops slowly with coated tools SM1105 until VB reaches 0.2 mm at most conditions (except at v = 43 m/min, f = 0.25 mm/r). Excessive tool flank typically resulted in tool breakage at the cutting edge for uncoated tools. Abrasive and adhesive wear of cutting tools were observed at low cutting speeds while diffusion and chemical wear occurred at higher cutting speeds.     

Drag Partition and Its Possible Implications for Dust Emission

The mechanisms for dust emission involve the saltation of sand-sized particles and the transfer of momentum from the atmosphere to the surface. Roughness elements on aeolian surfaces influence the transfer of momentum through the partition of total momentum flux into a pressure drag on roughness elements and a skin drag on substrate surface. The objective of this study is to better understand the mechanisms for momentum transfer over rough surfaces and drag partition, so that better dust-emission parameterization schemes can be developed. A large-eddy simulation model is implemented for the purpose. We perform computational simulations of turbulent flows over individual and arrays of roughness elements. Further, we examine how roughness elements affect drag partition and dust emission. The results lead to a possible new concept of dust emission over rough surfaces.     

建筑涂料生产废水的处理技术

采用混凝沉淀-芬顿试剂催化氧化-活性炭吸附工艺对建筑涂料生产废水的处理进行了研究。用硫酸铝作混凝剂,投加量为500mg/L:芬顿试剂法处理的废水pH为6.0,H2O2/COD值为4.0,FeSO4投加量为1540mg/L,氧化反应时间大于4h;活性炭投加量为0.2g/L时,处理后出水COD小于100mg/L。     

超临界水氧化法处理固体废物的研究进展

超临界水氧化法作为一种新兴的高级氧化技术具有广阔的应用前景,该方法在处理固体废物方面具有独特的优势。介绍了超临界水的特性和超临界水氧化法的反应机理及超临界水氧化法在固体废物处理方面的应用现状,提出了该方法要达到工业化应用亟待解决的理论和实际问题,对超临界水氧化法的发展方向进行了展望。