规范变换与误差修正结合的环境系统的前向网络和投影寻踪预测模型

为了建立适用于环境系统的结构简洁、形式统一、程序规范、应用普适的神经网络和投影寻踪回归预测模型,针对传统的神经网络和投影寻踪回归用于多因子、大样本预测建模,存在模型结构复杂、学习效率低的局限,提出设置环境系统预测量及其影响因子参照值和规范变换式的原则和方法,使规范变换后的影响因子皆"等效"于同一个规范影响因子,从而将多因子的的预测建模简化为等效规范因子的预测建模,使模型结构得到极大地简化,提高了学习效率;此外,为了提高预测模型的预测精度,还提出了对预测样本的模型输出值的误差修正公式.在对环境系统的预测量及其影响因子进行规范变换的基础上,将m个规范影响因子的每个建模样本组成m个"等效"训练样本,应用免疫进化算法优化模型参数,分别建立适用于环境系统的2个或3个规范影响因子的前向神经网络和投影寻踪回归两类预测模型;并依据误差理论,对误差修正公式修正后的模型预测精度的提高进行了严格的数学论证.将基于规范变换与相似样本误差修正相结合的两类预测模型,用于某市5个点位的SO_2浓度预测,并与6种传统预测模型和方法的预测结果进行了比较.结果表明:对同一个预测样本,同类模型的两种不同结构的的预测值及其相对误差都几乎完全相同或彼此相差甚小;此外,两种不同结构的两类预测模型用于5个样本预测,其相对误差绝对值的平均值分别为2.59%、2.67%;2.18%、2.62%,均远小于传统BP神经网络模型的25.72%、传统PPR模型的14.20%、传统SVR模型的22.13%、模糊识别模型的21.57%、组合算子模型的18.36%和多元回归模型的25.31%;而两类模型预测的最大的相对误差绝对值分别为4.11%和3.57%,更加远远小于传统的6种预测模型的37.18%、56.07%、27.40%、32.14%、38.38%和60.26%.实例分析结果证实了误差修正公式对提高模型预测精度具有切实可行性.基于规范变换与误差修正相结合的前向神经网络和投影寻踪回归两类预测模型不仅避免了"维数灾难",提高了学习效率和模型的预测精确度,而且具有简洁、普适、规范、统一和稳定的特点,对其他预测建模也有借鉴作用.     

快速测定法测定生化需氧量在环境监测中的应用

生化需氧量是指在规定条件下,微生物分解存在水中的某些可氧化的物质,特别是有机物所进行的生物化学过程中消耗溶解氧的量.目前对水体中的生化需氧量的测定除采用经典的稀释接种法外,已开始采用新方法,即微生物电极法.他能够在几分钟内测定水体的BOD含量,大大缩短了传统方法的五天培养时间,对于快速了解水体的有机污染状况,具有积极地的意义.     

Effects of COD/N ratio and DO concentration on simultaneous nitrification and denitrification in an airlift internal circulation membrane bioreactor

The effects of chemical oxygen demand and nitrogen(COD/N)ratio and dissolved oxygen concentration(DO)on simultaneous nitrification and denitrification(SND)were investigated using an airlift internal circulation membrane bioreactor(AIC-MBR)with synthetic wastewater.The results showed that the COD efficiencies were consistently greater than 90% regardless of changes in the COD/N ratio.At the COD/N ratio of 4.77 and 10.04,the system nitrogen removal efficiency became higher than 70%.However,the nitrogen rem...     

A QUARTER CENTURY OF INDUSTRIAL WATER USE AND A DECADE OF DISCHARGE CONTROLS1

This paper explores the trends in industrial water intake, discharge, recycling, and gross water use to see whether or not the 1972 Clean Water Act (CWA) has had an impact on industrial effluent discharge. Quinquennial Census data indicate that the levels of discharge, both generally and per unit of product, have been falling for as long as these data have been gathered. Trends in gross water use and recycling ratios suggest that during the 25 years of record production processes were gradually modified so that less total water was discharged and less was used per unit of output. Untreated discharge as a percent of all discharge fell fairly steadily across all industries until 1973 and continued to fall in 1978 in the major BOD-discharging industries. By 1978, 75 percent of the pulp and paper effluent and 40 percent of the food processing effluent was treated. The consistent increase in treated discharge in the pulp and paper mills, with their large component of BOD-related process discharge, was not matched by parallel trends in the steel, petroleum, and chemicals industries with their relatively smaller amounts (and percents) of process discharge. This suggests that the CWA may have been responsible in part for the change in the former. In the pulp and paper industry, there is further evidence that the CWA has influenced wastewater discharge. Although, for the century as a whole, pulp and paper mills discharged less water, and more discharge was treated, in 1978 than in 1973, these trends were especially dramatic among firms in the Northeast where controls were likely to have been most stringent. Finally, using the only direct evidence we have, it appears that the drop in discharge levels and the increasing amounts of treatment had a significant effect on the amount of BOD discharged to surface and ground water. In 1973 the pulp and paper mills in Wisconsin discharged an average of about 868,000 lbs/day; by 1982, despite increased levels of production, they discharged less than 10 percent of that. There is no doubt that industrial water use changed over the 25 years of record. Although the evidence is circumstantial, it appears that the CWA and the environmental ethic which spawned it played an important part in some aspects of the shifts.     

人工湿地不同基质和粒径对污水净化效果的比较

为研究人工湿地基质类型和粒径对水质净化效率的影响,选择了1~2、2~4、4~8 mm的沸石,2~4、4~8、8~16mm的砾石和2~4、3~5、6~8 mm的无烟煤基质,在无植物人工实验柱中开展单一基质的水质净化实验.结果表明,相同类型不同粒径的基质对COD、TN、TP的去除效果不同.4~8 mm沸石和砾石、6~8 mm无烟煤对COD的去除率最高,分别为53.74%、60.76%、62.93%;人工实验柱中氮素的去除以反硝化作用为主,粒径对TN去除效果的影响表现为小粒径更优;砾石和无烟煤的TP去除率也表现为小粒径更高,但沸石的TP去除率随着粒径的增大而增大.基质类型对COD、TP、TN的去除效果也存在差异.无烟煤对COD、TP、TN均有较好的去除效果,平均去除率在60%以上;沸石对TN的去除效果最好,TP去除率不高;砾石对COD有较高的去除率,对TP的去除效果一般.     

车用钛酸锂电池生命周期评价

为评估车用钛酸锂（LTO）电池对能源、环境与资源的影响,构建了包括重制与二次使用阶段在内的车用锂电池全生命周期评价模型,以某款国产纯电动客车用钛酸锂电池包为评价对象,计算得出每kW·h钛酸锂电池全生命周期的总能量消耗（CED）、全球变暖潜值（GWP）和不可再生矿产资源耗竭潜值（ADP（e））分别为2.80×10⁴MJ、1.86×10³kg CO₂eq.以及4.77×10^-3kg Sbeq.其全生命周期CED与GWP主要与两个使用阶段中由电池充放电效率引起的能量损耗相关,生产阶段GWP主要来源于正负极材料、铝制材料和N-甲基吡咯烷酮.基于全生命周期存储-释放每MJ能量的视角,发现二次使用可显著降低电池全生命周期GWP;与已有研究中其他锂电池对比可知LTO电池生产阶段GWP最低.     

区域碳固持服务供需关系动态分析——以北京为例

陆地生态系统的碳固持服务能直接固定大气中的CO₂,有效减缓全球变暖趋势。该服务的供需平衡对于区域的可持续发展至关重要。目前,以空间显式的方法,定量评估城市尺度上碳固持服务供需关系动态的研究还比较少。因此,论文以北京市为例,分别选取CASA模型计算的植被净初级生产力,以及IPCC清单法和城市碳代谢法计算的人为CO₂排放量,表征碳固持服务的供应和需求量。在此基础上,分析了北京市2000和2013年碳固持服务的供需变化。结果显示,2000年北京市碳固持服务供不应求,供需比为53.5%。空间分布上,中心城区的碳固持服务供需失衡,西部和北部地区的碳固持服务则供大于求。2000-2013年,北京市碳固持服务的供需关系趋于紧张,供需比降至38.5%。碳固持服务供需关系变紧张的主要原因是碳排放总量的增加。其中,来自城市居民生活和交通运输过程的碳排放增长最多。基于此,建议在需求端加快产业转移、促进节能减排,在供应端加大生态环境保护力度、保障区域的可持续发展。     

中国优势金属供应全球需求的风险评估

随着新一轮科技革命和产业转型的发展,全球金属资源供需格局发生重大调整,美国、欧盟、日本等主要发达国家不断倒逼中国敞开优势金属供应。为保障国家金属资源安全,论文从可依赖性、可持续性、可承受性3个维度建立了一套金属资源供应风险评估体系,对中国优势金属供应全球需求的风险进行评估,结果表明：1）中国优势金属整体供应风险较高,铟、铋等两种金属风险值都在80以上,处于高风险水平;锑、锗、钡、镁、钨、稀土等6种金属风险值都是60~80之间,处于中高风险水平;镓、锶等两种金属处于中风险水平。2）在10种中国优势金属中,钡的可依赖性风险最高,达到81.88,稀土的风险最低,只有42.42。铟的可持续性风险最高,达到81.80;锑的最低,风险值为69.46。铟的可承受性风险也最高,高达100;铋的次之,风险值为89.23;钡的最低,只有33.96。3）随着未来新兴产业的快速发展,中国优势金属的供应风险将更加严峻。     

Estimating preferences for outdoor recreation:: a comparison of continuous and count data demand system frameworks

Continuous and count data demand system models have emerged as attractive alternatives to the discrete choice random utility maximization models (RUMs) that currently dominate the seasonal, multi-site recreation demand literature. This paper compares the frameworks conceptually and investigates their empirical performance with a common data set. Although the two modeling approaches employ substantially different behavioral and econometric assumptions, results from a recreation application based on the 1997 Iowa Wetlands Survey suggest that qualitatively similar policy inferences arise from the competing structures.     

Temporal changes in demand for and supply of nests in red bishops (Euplectes orix): dynamics of a biological market

The red bishop (Euplectes orix) is a highly polygynous and colonial weaverbird. Males construct several nests within their territories to which they try to attract females, and females are solely responsible for incubation and raising offspring. In this paper, we describe the characteristics of the red bishop’s mating system as a biological market and investigate the role of nests built by males as a traded commodity in a mating market. As timing of breeding in red bishops in arid and semi-arid zones depends on rainfall patterns which are often unpredictable, there are temporal changes in demand for and supply of nests within a breeding season, with breeding activities of males and females being highly synchronised. We found that males increased their nest-building speed with increased female breeding activity independently of rainfall, indicating that supply follows demand in this mating market. The supply of nests was always larger than the demand for nests. Construction costs for nests increased with demand for nests as indicated by shorter nest-building duration and shorter building delays between two consecutively built nests at times of high breeding activity. Males as a trading class are chosen according to the age of their nests offered, with young nests having a higher probability of being accepted by females. Furthermore, female choosiness with regard to nest age decreased when their own market value decreased, as predicted by biological market theory. The temporal changes of breeding activity together with the female preference for young and fresh nests require that males quickly adjust nest-building activity to varying female demand for new nests. However, males with a better adjustment of building speed to female breeding activity did not gain higher mating success.