A simplified method for determining flame spread

The author discusses a small-scale fire test, which he proposes be used to determine flame-spread ratings for plastics during the development stages. Data on certain cellulosic materials indicate good correlation with the 25-ft tunnel test. Note: Based on a paper delivered by the author at the 22nd Annual Technical Conference of the Society of Plastics Engineers, March 12, 1966. At the time of the paper’s presentation, Mr. Levy was employed by the Pittsburgh Corning Corporation. He is currently with the Pittsburgh Plate Glass Company.     

低浓度煤矿瓦斯的利用方法

基于对煤矿低浓度瓦斯利用现状的分析,系统总结了低浓度瓦斯的利用方法和途径,指出煤矿瓦斯是影响煤矿生产和安全不可忽视的因素,而且低浓度瓦斯的排放不仅造成了严重的空气污染也造成了大量的资源浪费。     

A new rapid method for determining sludge activity

One of the most reliable methods for characterizing an activated sludge is by measurement of its activity. The measuring principle of the method developed is based upon the determination of glucose activity of the activated sludge. The activated sludge sample is continuously aerated in a reactor and glucose standard solution is given to it. The glucose uptake in the activated sludge system is measured by a glucose selective electrode. The sludge activity is calculated on the basis of the reaction time required for the 50% decomposition of the glucose. Only the change of dissolved oxygen concentration of the sample interferes the measurement. This interference is eliminated by the measurement of dissolved oxygen. The electrical response of glucose electrode is corrected with that of the oxygen electrode. The method is selective, the reproducibility of it is better than 10%.     

A risk-based method for determining passive fire protection adequacy

A risk-based approach to determine the adequacy of designed safety barriers in process plants is proposed and implemented to an offshore gas production platform. The scheme employs quantitative risk assessment method to assess the impact of selected process hazards and the adequateness of safety barriers based on a selected ALARP threshold value. The results obtained are further verified using emergency evacuation response analysis. Evaluations carried out on the designed fire/blastwalls for the selected case study confirmed the suitability of the proposed method.     

快速面积矩法绘制结构变形图

目前有面积矩法可以求解静定结构的变形和位移,本文提出的快速面积矩法不仅可以定量求解结构关键点的位移和转角,并且可以定量和定性地绘制结构变形图,该方法几何关系直观、概念清晰,降低了快速绘制结构变形图的难度。     

石材矿山胀裂剂的新用法

石材矿山是胀裂剂的最大用户。胀裂剂的主要用途也是用来开采石材。因为岩石属脆性物质。一般岩石的抗拉强度为50～250kg／cm^2，它的矿物结构特性决定了它经受不住瞬时、猛烈的动态爆力冲击，只能接受缓漫、有限的静态膨胀力作用。所以，原武汉工业大学于1982年就研制出JC-1型胀裂剂，曾荣获     

A modified logarithmic spiral method for determining passive earth pressure

In this study, a modified logarithmic spiral method is proposed to determine the passive earth pressure and failure surface of cohesionless sloping backfill, with presence of wall–soil interface friction. The proposed method is based on a limit equilibrium analysis wherein the assumed profile of the backfill failure surface is a composite of logarithmic spiral and its tangent. If the wall–soil interface is smooth, a straight line does not need to be assumed for the failure surface. The geometry of the failure surface is determined using the Mohr circle analysis of the soil. The resultant passive earth thrust is computed considering equilibrium of moments. The passive earth pressure coefficients are calculated with varied values of soil internal friction angle and cohesion, wall friction angle and inclination angle, and sloping backfill angle. This method is verified with the finite element method (FEM) by comparing the horizontal passive earth pressure and failure surface. The results agree well with other solutions, particularly with those obtained by the FEM. The implementation of the present method is efficient. The logarithmic spiral theory is rigorous and self-explanatory for the geotechnical engineer.     

Gibson地基模型参数的一种实用确定方法

Gibson地基在理论上可以考虑土体模量沿深度的变化，但工程应用中一直存在相关参数难以确定的问题。基于压缩试验成果和魏汝龙割线模量法双曲线模型，探讨提出确定单层和成层Gibson地基参数的实用新方法。该方法对压缩性状服从双曲线模型的土体较为适用。通过对浙江沿海地区若干典型工程的试验结果分析，结果初步表明地表处剪切模量为零的狭义Gibson地基在实际工程中几乎不存在。结合真空堆载联合预压加固软基的工程实例，对比分析了成层Gibson地基模型在沉降分析中的应用。新方法确定的成层Gibson地基模型不仅应用简便，而且可以显著地提高地基沉降预测结果的精度。在地基有效加固深度不是特别深厚的情况下，Gibson地基模型能较好地改进不能考虑模量随埋深变化的传统模型。