A SPATIAL LINEAR PROGRAM FOR OPTIMALLY SCHEDULING FOREST MANAGEMENT TO MEET STORMFLOW OBJECTWES1

ABSTRACT: A spatial linear program that strategically arranges and schedules forest treatments so as to meet peak stormflow objectives is formulated and demonstrated. The approach uses simulated spatial routing of stormflows nested as short‐term time schedules within longer‐term forest planning time periods. A simple case example is used to demonstrate the formulation and explore its spatial sensitivity.     

SIMULATED ANNEALING WITH MEMORY AND DIRECTIONAL SEARCH FOR GROUND WATER REMEDIATION DESIGN1

ABSTRACT: Review of recent literature indicates an emergence in the use of combinatorial methods such as simulated annealing in ground water management during the past nine to ten years. While previous studies demonstrated the feasibility of using these methods, a general finding was that computational processing requirements were inordinately high relative to gradient‐based methods. An enhanced annealing algorithm was developed and used to demonstrate the potential for greatly improving the computational efficiency of simulated annealing as an optimization method for ground water management applications. The algorithm incorporates “directional search” and “memory” capabilities. Selecting search directions based on better understanding of the current neighborhood of the configuration space was shown to improve algorithm performance. Also, “memory” concepts derived from the Tabu Search Method show particular promise for improving the rate and quality of convergence. Performance of the enhanced annealing method was evaluated and the resultant management method was demonstrated using an example from the literature.     

可持续发展与产业结构优化

可持续发展要求产业结构合理化、高度化、形成能够发挥资源禀赋比较优势的产业结构和发展环保产业,但是我国目前存在产业结构不合理、重复建设严重、地区产业结构趋同、产业技术水平低、第三产业发展不足、高新技术产业和环保产业发展滞后等情况,极不利于社会经济的可持续发展。为了真正的实现可持续发展,必须努力调整产业结构,淘汰落后过剩的生产能力,促进产业结构升级,大力发展第三产业、环保产业和高新技术产业。     

我国中小城市生活垃圾优化管理模型

根据我国中小城市生活垃圾基本特点,以区域优化、长期优化和综合处理优化管理为基本准则,以规划系统总处理费用最小为目标,提出我国中小城市生活垃圾处理的优化管理模型程序.模型程序为首先进行基础数据调查与评价,分析系统内生活垃圾状况,之后建立模型方程,通过参数赋值、求解,求出最终优化管理方案,为我国中小城市生活垃圾的运行组织管理和资本运行管理提供科学手段.     

Formation characteristics of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and coplanar PCBs in fly ash from a gasification–melting process of municipal solid waste

PCDDs/DF and Co-PCB (dioxin) formations were studied with ash from a newly developed gasification and melting process for municipal solid waste. Ash samples were heated in a laboratory-scale fixed-bed reactor. Emphasis was placed on the effects of the type and composition of ash, temperatures, gas residence time, and gaseous organic precursors. Investigations using macroscopic and homologue distribution analyses led to the following conclusion. The ash from the gasification–melting process had the ability to generate dioxins in flue gas. A possible carbon source is unburned carbon in the ash samples, although this was very low (less than 0.01%). An experimental result that the level of dioxins generated from preheated fly ash obtained from a conventional incinerator was much lower than that from nonheated fly ash supported this conclusion. Dioxin concentrations obviously showed temperature dependence and peaked at 350°C. Dioxins formed in a gasification–melting process ash were readily desorbed from the surface, probably because of the low carbon content of the ash. There was no experimental evidence that gaseous organic precursors fed to the reactor generated dioxins. Therefore, an organic precursor was not essential for the formation of dioxins. A good linear relationship obtained between PCDDs/DFs and gas residence time also supported the assumption. Received: February 14, 2000 / Accepted: June 30, 2000     

2018—2021年安徽省PM2.5和O3时空分布特征及其健康风险分析

利用2018—2021年安徽省空气质量监测数据分析了PM_2.5和O₃时空分布特征及其引发的健康风险。结果表明:从时间分布来看,2018—2021年安徽省PM_2.5年均值下降25.5%,而O₃-8 h年均值则保持持平;PM_2.5和O₃-8 h月均值具有明显的季节变化特征,PM_2.5月均质量浓度和超标天数均在冬季达到最大值,O₃-8 h月均值和超标天数则在夏季达到最大值。从空间分布来看,PM_2.5、O₃-8 h年均值和超标天数均为皖北最高,其次为皖中,最后为皖南。夏季O₃是主要的健康风险因子,冬季PM_2.5是主要的健康风险因子。当PM_2.5超标时,除2021年皖北地区外(PM₁₀是主要的健康风险因子),PM_2.5均是主要的健康风险因子;当O₃-8 h超标时,O₃是主要的健康风险因子。     

AFTER THE 1993 FLOOD: A WATER AND SURFICIAL BED SEDIMENT QUALITY SCENARIO ON THE ILLINOIS AND UPPER MISSISSIPPI RWERS1

ABSTRACT: Effects of the 1993 flood on river water and sediment quality were investigated using historical data and data collected from the Illinois River and Upper Mississippi River in a post‐flood period. Overall the post‐flood results showed systematic reductions and individual changes in the water and sediment constituents. The reductions in sediment metals and nutrients were most obvious at the Keokuk and Lock and Dam 26 stations. By analyzing and comparing the physical changes to the changes in water and sediment constituents at each station, it was found that physical processes such as sediment entrainment and, more importantly, the removal of fine sediment to be the main causes for the reduced concentrations in sediment constituents. On the other hand, sediment redistribution and associated secondary contamination could have caused the emergence of several water and sediment constituents that were undetected before the flood.     

减速机齿轮表面探伤优化选择

采用模糊集的贴近度计算对齿轮表面探伤方法进行了优化选择,表明旋转磁场探伤是齿轮表面探伤的最佳方法,在实用中检测出大量的正在延伸扩展的表面疲劳裂纹.     

内蒙高腐殖酸地下水中碘的分布特征与IDD病的关系

为探讨碘在高腐植酸地下水中的分布特征 ,研究内蒙古河套平原地区 51份水样 .分析结果显示 ,水质偏碱 (平均值 pH=7.91 ) ,水中腐植酸和 COD含量均高 ,地下水类型属于 HCO₃-Na和 HCO₃-Cl- Na型 .在这种高还原型盐水环境中水碘平均浓度达到 430 μg/L,超过了水碘安全浓度范围的上限 ( 5～ 200μg/L) .相关分析结果显示 ,水碘浓度与其它因素的相关顺序是 :COD>荧光强度 >电导率 >HCO^-₃>Cl^->Na⁺>pH>As>井深 .当地地下水中碘的分布呈现出碘浓度随腐植酸含量和盐渍化程度增加而增加的趋势 .由于这些因素的综合作用 ,当地没有发生高碘型碘缺乏病 ( IDD)的大面积流行 .     

华北地区气溶胶数浓度和尺度分布的航测研究 ——以石家庄为例

2009年秋季利用河北省人工影响天气办公室机载气溶胶粒子探头(PCASP-100X)和前向散射滴谱探头(FSSP-100-ER)在石家庄市上空进行了多次气溶胶观测.选取2009年9~10月间的7架次雾天、1架次小雨天及1架次密卷云天观测资料,重点研究雾天气溶胶粒子数浓度和直径的垂直、水平分布特征及粒子谱分布,并与密卷云天和小雨天的探测资料进行对比分析.结果表明:石家庄地区气溶胶粒子数浓度较高,近地面最大值达11910个/cm3.气溶胶粒子数浓度主要受天气条件影响,逆温层是影响粒子垂直输送的主要因素,在逆温层下粒子累积形成粒子数浓度的高值区,逆温层以上气溶胶粒子数浓度迅速减少,雾天和密卷云天粒子数浓度随高度多呈负指数分布;雾天多伴有逆温层和较大空气湿度,有利于气溶胶粒子累积,数浓度一般可达104个/cm3以上,容易形成低能见度污染天气;气溶胶粒子数浓度在无降水日有累积效应,降雨对气溶胶粒子有明显清除作用;粒子数浓度和粒子直径在水平方向上呈不均匀分布,随着高度增加粒子数浓度和直径的水平绝对偏差减小,相对偏差往往增大;不同天气下尺度谱型类似,多呈单峰分布,在0.11μm左右处出现峰值,但在雾天、密卷云天、小雨天气下的气溶胶粒子峰值依次变小,并且随高度增加,尺度谱峰值数密度值降低,谱变窄.