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511.
炼焦过程排放挥发性有机物的排放特征和组成分布研究 总被引:1,自引:0,他引:1
为控制炼焦排放以及为预防城市大气污染提供可靠的污染源数据支持,利用不锈钢采样罐和全自动预浓缩/GC/MS系统,研究了58-Ⅱ型和JN43-80型焦炉在装煤时刻和炼焦过程(包括装煤时刻)中挥发有机物(VOCs)的排放特征及其组成分布,分析了焦化行业排放VOCs的反应活性。研究发现,在装煤时刻和炼焦过程中,58-Ⅱ型焦炉产生的总挥发性有机物(TVOCs)浓度分别为7022μg/m~3和6266μg/m~3;JN43-80型焦炉产生的TVOCs浓度分别为4185μg/m~3和3298μg/m~3。装煤时刻产生的TVOCs浓度明显高于炼焦过程产生的。炼焦过程无组织排放的VOCs包含烯烃、烷烃、芳香烃、卤代烃以及少量的醛和酮,其中乙烯、乙烷、丙烯、苯、甲苯等为主要成分。这些产生的VOCs反应活性各不相同,活性最大的是烯烃类物质,其活性占TVOCs反应活性比重为(86.2±2.1)%;其次是芳香烃类物质,其活性比重为(9.2±3.1)%;反应活性最大的5个物种分别是丙烯、乙烯、1,3-丁二烯、1-丁烯以及苯乙烯。 相似文献
512.
基于1995~2010武汉城市圈城乡路网空间数据,综合运用复杂网络理论、动力系统理论及现代控制理论等多学科的方法和理论,采取随机故障和蓄意侵略两种攻击策略及多种评价指标,通过建立动力学演化模型并进行模拟仿真,揭示武汉城市圈城乡道路网的空间稳定性:(1)因分布相对均匀,节点连接随机多样,在面临随机攻击时,武汉城市圈城乡路网体现出“类随机性”,抗攻击能力强;(2)高度节点、高介数节点失效时,引致的城乡路网效率和结构变化程度不一,高介数节点失效往往更容易导致路网破碎和效率降低(形成众多子图);(3)桥梁和高速成为整个圈域城乡路网的关键边,不同桥梁或高速路段相对网络稳定性的重要程度不一样:圈域中心城区的大桥和二桥、南北向的京港澳、大广高速成为整个城乡路网的关键路径 相似文献
513.
Abstract The objective of this study was to investigate the effects of earthworm density on the availability of nutrients and heavy metals in metal contaminated soils. Pb/Zn mine tailings were mixed throughly with a red yellow podzolic soil at the ratio (w/w) of 75:25. Earthworms (Pheretima sp.) were introduced to the mixture at four different densities, zero, three, six and nine individuals per pot planted with ryegrass (Loliun multiflorum). The results indicated that earthworm activity significantly enhanced ryegrass shoot biomass. However, as denser earthworm population was introduced, shoot biomass tended to decrease. Earthworm activity significantly increased soil pH and availability of N, P and K in the tailings and soil mixture. There was a general tendency that uptake of Zn by ryegrass increased after earthworm inoculation, although the increase in extractable Zn in tailings and soil mixture was not significant. On the contrary, there seemed to be a lower uptake of Pb by ryegrass under earthworm inoclation, despite the fact that higher extractable Pb concentrations were observed. The present project indicated that the improved growth of ryegrass was due to improved nutrient availability and other soil conditions, by inoculation of earthworms at an appropriate rate. Further studies are needed to illustrate the relationship between metal availability and earthworm activity in the field. 相似文献
514.
System dynamics modeling for municipal water demand estimation in an urban region under uncertain economic impacts 总被引:1,自引:0,他引:1
Accurate prediction of municipal water demand is critically important to water utilities in fast-growing urban regions for drinking water system planning, design, and water utility asset management. Achieving the desired prediction accuracy is challenging, however, because the forecasting model must simultaneously consider a variety of factors associated with climate changes, economic development, population growth and migration, and even consumer behavioral patterns. Traditional forecasting models such as multivariate regression and time series analysis, as well as advanced modeling techniques (e.g., expert systems and artificial neural networks), are often applied for either short- or long-term water demand projections, yet few can adequately manage the dynamics of a water supply system because of the limitations in modeling structures. Potential challenges also arise from a lack of long and continuous historical records of water demand and its dependent variables. The objectives of this study were to (1) thoroughly review water demand forecasting models over the past five decades, and (2) propose a new system dynamics model to reflect the intrinsic relationship between water demand and macroeconomic environment using out-of-sample estimation for long-term municipal water demand forecasts in a fast-growing urban region. This system dynamics model is based on a coupled modeling structure that takes into account the interactions among economic and social dimensions, offering a realistic platform for practical use. Practical implementation of this water demand forecasting tool was assessed by using a case study under the most recent alternate fluctuations of economic boom and downturn environments. 相似文献
515.
Green shipping practices in the shipping industry: Conceptualization, adoption, and implications 总被引:1,自引:0,他引:1
Kee-Hung Lai Venus Y.H. LunChristina W.Y. Wong T.C.E. Cheng 《Resources, Conservation and Recycling》2011,55(6):631-638
There have been increasing concerns about the adverse impacts on the environment caused by cargo movement in international trade. Different stakeholders ranging from shippers and carriers to government bodies and international communities have expressed worries about the environmental impacts brought by shipping related activities. The pollution and waste created in the shipping processes have imposed environmental burdens and accelerated resource depletion. The situation is set to worsen in the face of intensifying trade globalization, which has contributed to sustained growth in international shipping activities. To help protect the environment, many shipping firms have taken the initiative to find ways to lessen the environmental damage of their operations while enhancing their performance. The objective of this study is to examine the environmental awareness and the environmental measures taken in the shipping industry. We propose a conceptual framework for evaluating green shipping practices and develop several propositions stating the conditions under which shipping firms would behave in an environmentally responsible manner. We conclude with managerial and policy implications of the conceptual framework to promote green shipping practices in the shipping industry. 相似文献
516.
Yi-Huey?Chen Wei-Chun?Cheng Hon-Tsen?YuEmail author Yeong-Choy?KamEmail author 《Behavioral ecology and sociobiology》2011,65(12):2329-2339
The rhacophorid frog, Kurixalus eiffingeri, is one of only a few frog species that exhibits polyandry and paternal care of eggs. Previous studies predicted that multiple
paternity within an egg clutch could influence the degree of paternal care and reproductive strategies. We used microsatellite
DNA markers to assess the prevalence of multiple paternity within egg clutches and the relationship between male paternal
care and the percent of male’s genetic contribution to the clutch, i.e., paternal share. We conducted field observations of paternal care and collected tissues from both male frogs and tadpoles
for parentage analyses. Our results showed that at least five out of 31 egg clutches had multiple paternity. Attending males
were always the genetic fathers of some, if not all of the eggs in the clutch they guarded. All egg clutches except one were
attended by one male frog but the attending male did not necessarily sire the majority of offspring. Multiple paternity in
all cases consisted of two fathers and one mother and most likely resulted from synchronous polyandry. Paternal care effort
correlated significantly with the male’s genetic contribution to the clutch, suggesting that male frogs adjust the effort
expended in care in response to paternal share. In addition, our results suggest that externally fertilizing species with
parental care and multiple paternity may develop novel reproductive and behavioral strategies to safeguard their parental
investment and overcome sperm competition. 相似文献
517.
Huei-Jen Tseng Ren-Chung Cheng Sheng-Hai Wu Sean J. Blamires I-Min Tso 《Behavioral ecology and sociobiology》2011,65(12):2351-2359
Animals may build multiple structures to provide benefits to counter the costs of building. Many orb web spiders add multiple
structures, e.g., barricading barrier webs and silk decorations, to their webs and these structures have been hypothesized
to function to deter predators or attract prey. The heavily armored spiny spiders construct barrier webs around their orb
webs and decorate them with conspicuous silk tufts. Why these organisms, already well protected by a thick cuticle and spines,
make the extra investment of building barrier webs and adding conspicuous silk decorations is not known. We predicted that
these structures function to both attract prey and deter predators. Field experiments were conducted in two consecutive years
using orb webs built by the East Asian spiny spider Thelacantha brevispina. We either (1) concealed the decoration, (2) removed the barrier webs, or (3) left the decorations and barrier webs intact.
We found year and treatment to interactively influence prey interception rates. In 2010, but not in 2009, we found prey interception
with T. brevispina webs to be greater when the decorations were conspicuous than when they were concealed suggesting that the decorations may
lure prey. Prey interception was lower when the barrier webs were present without decorations compared to when they were absent
without decorations. The prey-attracting function of the decorations thus may counter the reduction in prey interception incurred
by adding a barrier web. Predatory wasp interactions were not influenced by any of our treatments, probably because the spiders’
thick cuticle is the primary means of protection from wasps. Bird predation events, while rare, occurred only when decorations
were concealed or the barrier webs were removed. It is therefore plausible that the tuft decorations both lure prey and deter
birds. 相似文献
518.
北京建成区道路绿化空间结构和行道树健康状况 总被引:2,自引:0,他引:2
采用实地普查测量方法,定量研究了北京建成区188条道路行道树的树种结构、径级分布、立木层次和健康状况。结果表明,国槐(Sophora japonica)、毛白杨(Populus alba)、银杏(Ginkgo biloba)是建成区主要行道树种,使用量分别占研究区树木总株数的54.7%、13.7%和7.4%。建成区树木... 相似文献
519.
贵州浓香型白酒大曲中霉菌的18S rDNA系统发育分析 总被引:4,自引:0,他引:4
从贵州某名酒厂大曲中分离到104株丝状真菌(霉菌),通过形态特征和生理特性检测等传统鉴定方法,初步把形态和生理生化特征一致的霉菌归类为14个大类群;并采用18S rDNA序列分析,进一步把菌株归类为MJ-I至MJ-V五个类群,随后构建系统发育树.结果表明,样品中的霉菌以曲霉属(Aspergillus)为主,占总分离菌数... 相似文献
520.