Approach of technical decision-making by element flow analysis and Monte-Carlo simulation of municipal solid waste stream

This paper deals with the procedure and methodology which can be used to select the optimal treatment and disposal technology of municipal solid waste （MSW）, and to provide practical and effective technical support to policy-making, on the basis of study on solid waste management status and development trend in China and abroad. Focusing on various treatment and disposal technologies and processes of MSW, this study established a Monte-Carlo mathematical model of cost minimization for MSW handling subjected to environmental constraints. A new method of element stream （such as C, H, O, N, S） analysis in combination with economic stream analysis of MSW was developed. By following the streams of different treatment processes consisting of various techniques from generation, separation, transfer, transport, treatment, recycling and disposal of the wastes, the element constitution as well as its economic distribution in terms of possibility functions was identified. Every technique step was evaluated economically. The Mont-Carlo method was then conducted for model calibration. Sensitivity analysis was also carried out to identify the most sensitive factors. Model calibration indicated that landfill with power generation of landfill gas was economically the optimal technology at the present stage under the condition of more than 58% of C, H, O, N, S going to landfill. Whether or not to generate electricity was the most sensitive factor. If landfilling cost increases, MSW separation treatment was recommended by screening first followed with incinerating partially and composting partially with residue landfilling. The possibility of incineration model selection as the optimal technology was affected by the city scale. For big cities and metropolitans with large MSW generation, possibility for constructing large-scale incineration facilities increases, whereas, for middle and small cities, the effectiveness of incinerating waste decreases.     

PATTERNS OF SUSPENDED SEDIMENT TRANSPORT IN A COASTAL ALASKA STREAM1

Suspended sediment data from a 154 ha watershed on northeast Chichagof Island, Alaska, were collected over three fall storm seasons from 1980 to 1982. Sediment rating curves for nine pooled storms explained less than 34 percent of the variation in total suspended solids (TSS). Significantly higher concentrations of suspended sediment occurred during the rising limb of storm hydrographs than for similar flows on the falling limb, accounting for hysteresis loops in TSS versus streamflow plots for individual storms. These hysteresis loops were wider during early season storms, indicating that easily transportable fine sediment may have been flushed from the upper portion of channel banks and from behind large organic debris during early season peak flows. Regression relationships (TSS versus Q) developed for the highest stormflows (> 1 m³/s) had steeper slopes than the lower stormflows (< 1 m³/s). Turbidity correlated well (r=0.94) with TSS for all storm-flow data combined. Organic matter constituted an average of 35 percent (by weight) of TSS for all water quality samples.     

高大建[构]筑物的共振震害

分析了国内外典型地震的共振震害个例。论述了致灾的长周期和大振幅地震波形成规律：①地震波周期随震级和震中距而增大;②长周期波出现与地基类型有关,软弱地基能传递长周期地震波,地基越软弱,越厚所能传递的波周期越长;③松软地基对地震波起放大作用,特别是表层松软、下层坚硬的地基,放大作用更显著,对高大建筑物危害更大。提出了减轻共振震害的对策。随着经济发展,高大建筑和结构物越来越多,潜在震害日益加重,研究共振震害对防震减灾具有现实意义。     

大负载高温变率高低温试验系统

目的研制一种闭合循环单回路方式的大负载高温变率高低温试验系统,并介绍其设计思路和关键技术,其有效负载高达1.0 t(铝),温变率最高可达5℃/min以满足产品的实测需求。方法针对大负载高温变率的要求,对加热制冷的方式以及功率进行设计;针对试验系统试验舱大空间、大负载等特点所造成的空间温度梯度大,波动剧烈的难点,对各个系统进行协调设计,特别提出低温系统的引射雾化设计以及温度积分分离的控制策略等创新点。结果高低温试验系统工作区的温度在升温阶段实现了较好的温度变化跟随性,在稳定阶段具有较好的空间均匀性和波动性,工作区各点温度均匀性≤2℃,温度波动度性≤±0.5℃。结论采用闭合循环单回路方式,并通过低温系统的引射雾化设计以及温度积分分离的控制策略,可以实现大负载高温变率高低温试验系统的空间均匀性和波动性以及温变跟随性的要求。     

基于应变模态方法的飞机蒙皮分布动载荷识别

目的解决飞机蒙皮分布动态载荷确定的工程实际问题。方法将基于广义正交多项式的复杂分布动载荷识别技术与应变模态理论相结合,建立利用有限个测点的应变响应和结构应变频响函数作为已知参数的飞机蒙皮分布动载荷识别模型。利用Nastran软件,以某型飞机机身中段外蒙皮为例,分别采用位移模态方法和应变模态方法进行了70、80、90、100 Hz下的蒙皮分布动载荷识别,并进行对比分析。结果以应变响应作为已知参数的应变模态载荷识别方法,在各计算频率下均具有较好的识别精度,最大识别误差为8.9%,能够满足工程应用。在各识别频率下,采用应变方法识别过程中的积分矩阵条件数小于位移方法。在100 Hz识别频率下增加3%随机误差干扰后,位移识别方法最大误差为19.4%,采用应变方法的载荷识别最大误差为9.8%。结论相比于传统的采用位移模态的载荷识别方法,以应变响应作为已知参数的应变模态载荷识别方法具有更好的数值稳定性,对于解决结构共振频率附近频响函数矩阵奇异性问题具有很好的应用价值。     

公共大空间建筑生化恐怖模式和通风技术分析

公共大空间建筑生化恐怖模式主要有制造火灾产生毒性气体、爆炸毒气弹分散毒性物质和人工直接布洒毒性物质。分析表明:火灾烟气受热浮力作用,在建筑物上部出现明显的烟气层,采用自然或机械排烟能有效地减缓或控制烟气层下降;爆炸分散毒性物质,除了爆炸点周边区域外,毒气扩散受热气流诱导,以及浓度差引起的运动;不考虑室内对流气流的影响,人工布洒毒性物质产生的毒性气体,其扩散主要是由浓度差引起的。不同类型恐怖袭击产生的毒性气体受室内对流气流的控制,合适的通风方式能够控制毒性气体的扩散和输运过程。但能否采用某一形式的通风系统兼备防范不同类型的恐怖袭击,需要对通风系统的通风量、气流组织和控制方式做更深入的研究。     

一株纤维素分解茵利用枳实废渣产酶条件的研究

以枳实废渣为碳源，对产纤维素酶G2茵进行固体发酵，通过测定FPA、CMC、C1酶活的大小，对其产酶条件进行优化研究。结果表明产酶最适条件为：枳实在发酵前需进行酸处理；氮源为硫酸铵；含水率为70％；初始pH为5～6；发酵周期为6天。在以上最适条件下，G2菌酶活力为FPA：31．8IU／ml，CMC：11．86IU／ml，C1：15．79IU／ml。     

大空间内机械排烟效果的实验研究

在一个全尺寸的大空间火灾实验厅内,进行了不同补风口位置和补风口面积下的机械排烟试验.结果表明,由于烟气的温度较低,烟气和补充的空气较易混合,烟气和空气在交界处存在着较强的质量交换.排烟过程中,烟气是边稀释边被排放,很难和空气实现完全置换.低温烟气进行机械排烟时,区域模拟思想不适用,较难将烟气控制在理论高度.补气口位置和面积对烟气排放及火源燃烧状况具有一定的影响.     

计算机模拟在火灾科学与工程研究中的应用

计算机模拟技术尤其是场模拟技术是近年来发展完善的高新技术,在许多工程领域和基础研究方面得到广泛应用。但其在大灾科学和工程领域的应用研究刚刚起步。本文在介绍场模拟基本方法的基础上,重点介绍了场模拟方法中大涡模拟技术的基本理论和方法,并将其引入火灾动力学的研究中。列出了火灾动力学大涡模拟的基本方程、湍流模型、燃烧模型和幅射模型。并用此方法模拟了油罐区火灾动力学演化实例,据此可提出更有效的控制和补救措施。 通过利用场模拟方法中的大涡模拟技术研究典型工业重点火灾危险源——油罐区火灾动力学演化实例,可以看出场模拟技术在安全工程领域方面的发展前景。预计它将成为安全工程领域中的安全管理、危险性评估以及安全事故处理决策支持等的有效手段。     

低应变反射波法基桩动测资料分析中的若干问题探讨

本文对低应变反射波法基桩动测资料分析中存在的信号分析方法、尺寸效应、桩周土的影响等问题的最新研究进展进行了分析,并且对相应问题给出了一些建议和可能的解决方法.