Inhibition of aluminum powder explosion by sludge-based carbon nanotubes/phosphorus-nitrogen flame retardant composite powder: Mechanism and kinetic model

Reducing or eliminating aluminum powder explosions is of great significance to preventing and reducing aluminum industry disasters. In order to find an appropriate way to prevent and alleviate the hidden danger of aluminum powder explosion, a sludge-based carbon nanotube (MS@CNTs) carrier with excellent performance was constructed in this paper, and the MPP-MS@CNTs composite powder was prepared by in-situ synthesis technology. The explosion flame propagation and pressure suppression experiments show that the composite powder can more effectively suppress the explosion of aluminum powder. When adding 60 wt% composite detonation inhibitor, the explosion inhibition of aluminum powder can be achieved. Combined with the methods of Redfern, Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose, it was found that the activation energy of aluminum powder increased after adding detonation inhibitor. Its inhibitory effect is theoretically demonstrated. The material properties before and after the explosion were compared and analyzed through characterization tests. Combined with pyrolysis characteristics, the inhibition mechanism of composite powder mainly includes coating inhibition, porous adsorption isolation, decomposition endothermic, and product oxidation, which provides a theoretical and practical basis for the prevention and control of explosion and fire accidents in the aluminum industry.     

伺服电动机的振动抑制

分析了振动产生的原因,从大量文献中总结了目前振动抑制的主要方法,对扭转振动和转矩脉动的抑制方法、从动态指标和系统结构上进行分析和对比,指出了目前振动抑制方法存在的问题,对振动抑制方法的发展进行展望。     

螺旋藻抗突变作用的探讨

为探讨螺旋藻抗突变作用的机理,用钝枯螺旋藻（SPG）为受试物,用3种不同的给予方法观察其拮抗由黄曲霉毒素（AFB1）所致的TA98菌株突变的作用。结果表明：SPG在较低浓度（40mg/皿）即可通过抑制AFB1对TA98的致突变作用,使突变菌落数明显减少;当SPG达到较高的浓度（100mg/皿）时,还可通过直接灭活AFB1的方式抑制AFB1的致突变作用。其可能机制是由于SPG中含有胡萝卜素、Vitc和葡萄糖醛酸等成分。前两者都已被证实具有抗突变和清除自由基的功能,而葡萄糖醛酸则可与AFB1结合使其灭活。结果还显示,SPG不能抑制AFB1引起的已突变的TA98菌株的突变表达。     

Suppression of methane/coal dust deflagration flame propagation by CO2/fly ash as a flue gas layer

To reveal the suppression characteristics of methane/coal dust deflagration flame propagation by the flue gas loading in local zones. The suppression experiments of flue gas layer (CO₂ and fly ash) with different thicknesses and fly ash concentrations were conducted in semi-open vertical combustion pipe. The flue gas layer was produced by self-designed flue gas layer generator. Flame propagation characteristics which including the flame image, velocity, the ion current and temperature were recorded by the high-speed photography, the ion current probe and the thermocouple. The residues after coal dust deflagration were characterized by FTIR (Fourier transform infrared spectroscopy). The results show that the flue gas layer has a significant suppression on deflagration flame propagation. With the increasing of flue gas layer thickness and fly ash concentration, the flame velocity, height, temperature and the ion current gradually decreases, and the suppression effect was enhanced. The asphyxiation of CO₂, heat absorption and insulation of fly ash were mainly methods for the suppression of coal dust deflagration flame.     

中国工程爆破协会简介(2010年12月)

<正>中国工程爆破协会是由国务院国有资产监督管理委员会主管,由民政部、公安部、国家安全生产监督管理总局、中国有色金属工业协会等领导部门指导下的全国从事工程爆破的22个部门系统的企事业单位组成的行业性社会团体。     

An investigation on the aluminum dustexplosion suppression efficiency and mechanism of a NaHCO3/DE composite powder

A NaHCO₃/diatomaceous earth (DE) composite powder suppressant with unique clustered structures is prepared by high-pressure impact method, using DE as the carrier and NaHCO₃ as the loaded chemical suppressant. The purpose is to obtain affordable, environmentally friendly, high-efficiency power explosion suppression materials. The suppression efficiencies of the NaHCO₃/DE composite powder suppressant on aluminum dust propagation and explosion pressure are tested. The results show that as the content of the NaHCO₃/DE composite powder suppressant increases, the maximum flame length gradually reduces and the suppression efficiency gradually increases. Addition of 60 wt% of the NaHCO₃/DE composite powder suppressant suppress aluminum dust flame propagation and addition of 100 wt% of the NaHCO₃/DE composite powder suppressant can fully suppress aluminum dust explosion. Comparison with pure NaHCO₃ and pure DE reveals that NaHCO₃/DE composite powder suppressant is more effective in suppressing aluminum dust flame propagation and aluminum dust explosion pressure than either of the two powders alone. The suppression mechanism of the NaHCO₃/DE composite powder suppressant is established: On the one hand, reaction is suppressed by the decomposition of NaHCO₃ and the product of this decomposition; on the other hand, as DE is rich in porous structures, when the loaded NaHCO₃ powder separates from DE, the porous structures will not only limit flame propagation, but will also well adsorb the substances generated from explosion reaction.     

宽带接入网中的动态压缩技术

针对链路层数据压缩的问题,以HFC网络为背景,结合DOCSIS系统中的数据压缩方法和网络数据特征,提出一种动态压缩策略。该策略根据数据压缩速率、数据到达速率以及压缩比之间的关系,动态地启用压缩技术,可以进一步提高网络吞吐量,降低设备的资源耗用,提高设备的处理能力。实验证明了该策略的可行性。     

隧道内细水雾抑制火灾事故的数值仿真

以工业灾害的抑制技术为背景,针对隧道内发生的火灾事故,采用数值仿真技术研究连续喷射水雾阻挡气相物质燃烧的过程.并讨论水雾抑制燃烧的机理.相比于欧拉/欧拉方法,欧拉/拉格朗日方法能较好地描述水雾液滴引起的瞬时流动特性及变化经历,利用欧拉/拉格朗日方法,对气相反应流及水雾扩散过程进行数值研究.应用颗粒随机轨道模型,来考察湍流对水雾液滴扩散的影响.比较了有、无水雾抑制时和水雾不同初始流量下,隧道内流场的温度分布情况,揭示了水雾液滴的运动特性,为火灾事故抑制技术的发展提供理论依据.     

一种改进的自适应中值滤波算法研究

非线性滤波是一种有效的噪声抑制技术,已得到了广泛的应用。针对标准中值滤波方法存在的不足,提出自适应中值滤波方法。该方法采用一定的检测标准对图像中的噪声点进行检测,并采用改进的中值滤波方法对噪声点进行滤波。实验结果表明,此方法较标准中值滤波法具有更优良的滤波性能。     

电流变效应在抑制车削振动中的应用

利用电流变效应设计制造了车床活顶尖电流变减振器,在减振器的活动电极板与固定电极板间注满电流变液。计算机模拟和切削试验结果表明,采用电流变减振器,可以使车床尾座活动顶尖的振动响应幅值减小约３０％。