应急救援多目标时限指派模型

为实现应急救援队伍的合理派遣,对应急救援队伍的救援效率、救援物资消耗、最佳救援时间等因素进行分析。突出应急救援的时效性和救援目标的多属性特征,提出在保证应急救援最短时限的前提下,以应急救援效率最大化、物资消耗最小化为优化目标,构建最短时限应急救援多目标指派模型。采用线性加权和法将多目标化为单目标决策问题,运用两阶段法对模型进行求解。数值计算结果表明:最短时限的引入能有效实现应急救援队伍合理、公平派遣。     

基于ANSYS的可靠度分析方法及应用

通过对可靠度分析的概述理解到现代工程分析中实体模型不确定因素众多,进而带来分析的不准确性。基于有限元分析软件ANSYS提供的概率设计系统(PDS)的概率分析功能,使对结构的概率分析非常容易。根据结构的失效模式来确定结构功能函数,由此建立结构极限状态方程,再运用结构可靠度分析中的蒙特卡洛法(MCS法)利用结构的失效频率来估算其失效概率。在本文中提出了利用ANSYS的概率分析功能结合MCS法进行结构的可靠性分析的方法,并通过一个实例具体说明了利用ANSYS的概率分析功能实现结构的可靠性分析的可行性。     

第三方挖掘作用下管道可靠性评估研究

为研究第三方损坏中挖掘作用对管道可靠性的定量影响,阐述了第三方挖掘作用下管道失效模式与失效机理,确定了管道第三方挖掘作用下的2个极限状态:穿孔失效和凹陷—划伤失效,提出了1种综合考虑管道运行及管理条件,建立了管道第三方挖掘极限状态方程求解其失效概率的模型。以某长输天然气管道为例,基于蒙特卡洛模拟计算了研究管段的失效概率值,并进行了参数的敏感性分析。结果表明,该方法能够定量描述第三方挖掘对管道可靠性的影响程度,评估结果便于管理者制定相应的维修维护策略。     

不同粒径镁铝合金粉尘爆炸与抑爆特性研究

为了研究镁铝合金粉爆炸危险特性,利用20L球形爆炸容器进行测试,结果表明:180目 (80 μm)、 120目(125 μm) 和60目(250 μm)3种粒径下的金属粉尘爆炸下限浓度分别为45 g/m3,55 g/m3和95 g/m3。相同浓度下最大爆炸压力随粒径增大的而减小。以碳化硅和石墨为代表的研究中,60目,120目和180目的镁铝合金粉以10%的浓度梯度加入碳化硅浓度分别至50%,70%和80%,石墨浓度至30%,50%和60%时,镁铝合金粉不会发生爆炸。表明碳化硅及石墨等惰性粉尘都能对粉尘爆炸有抑制作用,其中石墨对镁铝合金粉的抑爆作用明显优于碳化硅。     

USING UNCENSORED TRACE-LEVEL MEASUREMENTS TO DETECT TRENDS IN GROUND WATER CONTAMINATION1

ABSTRACT: Environmental decision making involving trace-levels of contaminants can be complicated by censoring, the practice of reporting concentrations either as less than the limit of detection (LOD) or as not detected (ND) when a test result is less than the LOD. Censoring can result in data series that are difficult to meaningfully summarize, graph, and analyze through traditional statistical methods. In spite of the relatively large measurement errors associated with test results below the LOD, simple and meaningful analyses can be carried out that provide valuable information not available if data are censored. For example, an indication of increasing levels of contamination at the fringe of a plume can act as an early warning signal to trigger further study, an increased sampling frequency, or a higher level of remediation at the source. This paper involves the application of nonparametric trend analyses to uncensored trace-level groundwater monitoring data collected between March 1991 and August 1994 on dissolved arsenic and chromium for seven wells at an industrial site in New York.     

石油化工生产中使用可燃性气体检测报警仪表若干问题的探讨

介绍了可燃性气体检测的基本原理、检测探头应具备的抗干扰能力，并探讨了探头的布点方法和注意事项、仪表的标定及报警点设置、管理维护等问题。     

增压器式超高压水射流切割机产品化体会及展望

作为我国高压水射流切割机的第一个产品即“大地水刀”,已进入市场两年多了。笔者以此为背景,介绍增压器式水切割机的超高压发生器及切割部分;讨论其主要部件、零件结构设计及关键技术。尤其在产业化中,对高压缸体疲劳寿命和高压动密封可靠性等问题解决方案作深入探讨;给出在相关技术方面近期的发展。最后,结合我国水切割机技术的提高和推广,提出初步的看法和建议。     

五氯硫酚锌盐粉尘爆炸下限浓度的实验研究

五氯硫酚锌盐的一些基本的危险性参数,如燃烧爆炸性能,目前国内外报道极少。笔者采用野外定性燃烧试验、哈特曼管实验及20 L球实验,对该物质粉尘爆炸的危险性进行研究。结果表明,该物质具有燃烧爆炸危险性,但与细小片状铝粉(燃爆危险性很强烈)相比,其粉尘的燃爆危险性很弱。以硅系点火具作为点火源,在20 L爆炸球中测试获得该粉尘爆炸下限浓度约为213 g/m3。根据ISO-6184及VD I-3673等标准,认为该粉尘的爆炸猛烈度为1级。所得结果为该物质的生产及使用安全提供了重要的参考。     

Flammability Properties of Virgin and Recycled Polycarbonate (PC) and Acrylonitrile–Butadiene–Styrene (ABS) Recovered from End-of-Life Electronics

Acrylonitrile–Butadiene–Styrene (ABS), Polycarbonate (PC) and their alloys are widely used in automotive industry, computer and equipment housings. With increasing disposal of end-of-life electronic equipment, there is also an increased demand for recycling of these materials so that they do not pose environmental challenge as solid waste. One of the recycling approaches is mechanical recycling of these thermoplastics where recycled plastic is melt blended with virgin materials to obtain a high quality product. Besides obtaining desirable mechanical properties, such blends should also conform to fire safety standards. In this work, a series of blends were prepared using PC and ABS recovered from discarded computers and virgin materials using a twin-screw extruder. Their flammability properties were evaluated using burner flammability tests and Ohio State University (OSU) release rate tests. It was found that the extinguishing time, burning extent and weight loss appears to progressively decrease with the addition of both virgin or recycled PC to virgin or recycled ABS. It was also seen that the addition of the 70% of PC, virgin or recycled, to ABS virgin or recycled, appears to significantly decrease heat release and smoke evolution. The results of this study indicate that recycled polycarbonate can be used as an additive for virgin or recycled ABS, as a means of giving flame resistance to ABS in high-value applications. This result is significant when related to the result obtained by a separate study indicating that up to 25% of recycled material can be used without degradation of mechanical properties in the presence of 15% short glass fiber reinforcement.