神经网络与模拟退火算法结合的锅炉低NOx燃烧优化

对某600MW燃煤电站锅炉进行了多工况热态NO_x排放特性测量,在利用多层前向神经网络对该锅炉的NO_x排放特性进行建模的基础上,将神经网络模型与模拟退火全局优化算法相结合,实现了锅炉的低NO_x燃烧的优化,计算得到可获得低NO_x排放浓度的具体燃烧配风方案.文中对2种不同退火参数的模拟退火算法进行了比较,结果说明采用T₀=50K,α=0.6的参数可以获得较好的寻优效果.本文研究结果为实现大型电站锅炉低NO_x燃烧控制的在线优化技术打下了基础.     

雨水管道沉积物沉淀特性及主要污染物含量分布

为研究雨水管道沉积物的沉淀特性和污染物含量特征,在武汉市对建筑(包括住宅小区)、道路和绿地3种用地类型的雨水管道沉积物进行采样和分析.沉速测试结果表明,高沉速颗粒在沉积物中所占比例较大,建筑和道路中沉积物的沉速分布相对稳定,建筑、道路和绿地中沉速大于3.00 cm·s-1的颗粒占比依次递减.粒径分析结果显示,沉积物粒径分布范围较广,大多集中在13~628μm范围内,且同种用地类型沉积物粒径分布差别很大.按沉降速度将每份沉积物样品分为7组,分析化学需氧量(COD)、总氮(TN)和总磷(TP)含量与沉降速度之间的联系.结果表明,沉速大于3.00 cm·s-1和小于0.025cm·s-1的沉积物中污染物含量较低,但高沉速沉积物中污染物总量较多.对沉积物样品整体而言,各用地类型COD含量从高到低依次为:绿地道路建筑;道路雨水管道沉积物中氮含量较低,其余两种用地中含量接近;建筑区雨水管道沉积物中磷含量较高,其余两种用地中含量接近;COD∶TN在(51~89)∶1之间,COD∶TP的值在(102~186)∶1之间.     

基于BP网络的建筑安装施工现场安全综合评价的研究

针对目前我国建筑安装施工现场安全评价技术的不成熟和欠科学性的现状 ,笔者分析和综合了目前安全评价技术 ,结合建筑业特点 ,提出了基于BP神经网络的建筑安装施工现场安全评价方法 ,并对该评价模型的原理、方法及算法进行了研究。首先 ,结合建筑安装施工现场安全生产的特点建立评价指标体系 ,随后 ,运用层次分析法确定指标及准则层的权重 ,并运用模糊综合评价法生成评价样本集 ,最后 ,利用样本集训练BP网络 ,待误差满足要求后 ,即可运用训练成功的BP神经网络进行安全评价。     

水环境模拟中多孔介质场空间变异性研究方法述评

阐述了研究多孔介质空间变异性的经典统计法、地质统计学方法以及新兴的分形方法.经典统计方法由于不考虑研究对象的空间相关性,已经不能对这种变异性做出客观的分析;地质统计学方法很好地克服了经典统计学的缺点,是目前应用最多的一种方法;分形的研究对象为无规则和具有自相似性的体系,这一特性决定了它研究这种变异性有着独特的优点.最后对多孔介质空间变异性研究的趋势进行了展望.     

腐殖酸钠和表面活性剂对黄土中石油污染物解吸增溶作用

选用十二烷基苯磺酸钠(LAS)、十二烷基硫酸钠(SDS)和十二烷基磺酸钠(SAS)对污染的土壤进行解吸实验,研究了这3种阴离子表面活性剂和腐殖酸钠对黄土中柴油类污染物的协同增溶作用.结果表明,腐殖酸钠和3种阴离子表面活性剂对黄土中柴油的解吸均有显著增溶作用,使柴油的解吸量明显增加,柴油的去除率最高可达63%.SDS对柴油的解吸量随腐殖酸钠浓度增大呈线性增加关系;但腐殖酸钠浓度增加对 LAS和SAS的解吸曲线有突越点,超过此浓度后反而会抑制解吸作用.     

企业安全评价分析的主成分方法

依据某机车车辆厂的特点,建立了安全性评价指标体系,并应用主成分分析法对数据进行分析处理,求出指标综合表达式和排序结果,从而得到指标的客观权重,并指出了主成分法应用于安全评价中的特点。     

中国食品工业可持续发展现状分析与对策——基于河南、四川、青海三省食品企业的调查

改革开放30多年来,中国的食品工业有突飞猛进的发展,食品企业的生产能力大幅提升,但中国食品工业仍然存在着诸如食品质量体系不健全、食品安全隐患大等问题.分析了我国食品工业可持续发展生产的背景,然后就河南、四川、青海三省的食品企业可持续发展生产状况做了问卷分析.根据问卷分析结果,从政府层面、企业层面、社会层面提出促进我国食品工业可持续发展的建议.     

Influence of Polyol Plasticizers on the Properties of Polyvinyl Alcohol Films Fabricated by Melt Processing

In this work, high-alcoholysis polyvinyl alcohol (PVA) films were fabricated by melt processing and the plasticizing effect of compound polyol plasticizers on PVA were investigated with X-ray diffraction (XRD), differential scanning calorimetry (DSC), rheological measurements, mechanical tests etc. Hydrogen bonding interactions occurred between PVA and plasticizer. With the increase of plasticizer, the flowability of PVA was improved and reached the maximum value at the plasticizer of 20%. Glass transition temperature (T _g) and melting point (T _m) decreased with the increase of plasticizer content. For the heterogeneous nucleation effect of plasticizer, new polymorph of PVA formed. The viscosity was sensitive to the shear rates. The incorporation of plasticizers into PVA resulted in the increase of elongation at break and impact strength, as well as the decrease of tensile strength.     

Characterization and control of odorous gases at a landfill site: a case study in Hangzhou, China

Municipal solid waste (MSW) landfills are one of the major sources of offensive odors potentially creating annoyance in adjacent communities. At the end of May 2007, an odor pollution incident occurred at the Tianziling landfill site, Hangzhou, China, where the residents lodged complaints about the intense odor from the landfill, which drew a significant attention from the government. In this study, ambient air monitoring was conducted at the Tianziling landfill site. The main odor composition of the gas samples collected on June 1st 2007 and the reduction of various odorous gases from the samples collected on June 1st 2009 due to the applied odor control techniques were determined using gas chromatography-mass spectrometry (GC-MS). In addition, variations of primary odorous gaseous (NH₃ and H₂S) concentrations at different locations in the landfill site from July 2007 to June 2009 were also investigated by using classical spectrophotometric methods. Results showed that a total of 68 volatile compounds were identified among which H₂S (56.58-579.84 μg/m³) and NH₃ (520-4460 μg/m³) were the notable odor components contributing to 4.47-10.92% and 83.91-93.94% of total concentrations, respectively. Similar spatial and temporal shifts of H₂S and NH₃ concentrations were observed and were significantly affected by environmental factors including temperature, air pressure and wind direction. Odor pollution was worse when high temperature, high humidity, low air pressure, and southeast, northeast or east wind appeared. Moreover, the environmental sampling points of the dumping area and the leachate treatment plant were found to be the main odor sources at the Tianziling landfill site. The odor control technologies used in this project had a good mitigating effect on the primary odorous compounds. This study provides long-term valuable information concerning the characteristics and control of odors at landfill sites in a long run.     

Poly(Ethylene Glycol) Grafted Starch Introducing a Novel Interphase in Poly(Lactic Acid)/Poly(Ethylene Glycol)/Starch Ternary Composites

The main purpose of this study is challenging to dramatically improve the toughness of poly(lactic acid) (PLA)/starch by adding poly (ethylene glycol) (PEG) into the composites and grafting PEG molecules onto the surface of starch particles. It was found that the surface grafting of PEG onto starch induced the presence of PEG-rich regions located around the starch particles, caused by migration and aggregation of free PEG molecules. A novel interphase transition layer between PLA and starch was formed, which showed great ability for cavitation and vested large-scaled plastic deformation to PLA matrix. Further mechanical properties tests indicated the formation of interphase layer significantly increase the elongation at break from 10.2 to 254.5%, and notched impact strength from 1.56 to 2.37?kJ/m² for PLA/PEG/starch ternary composites. The influence of PEG component, ethanol extraction and annealing was also investigated.