岩溶地基土洞塌陷评价及处理

地下水(地表水)产生的渗透潜蚀作用、崩解作用等是土洞形成和发展的重要原因。对工程实例中的土洞,采用极限平衡法和压力拱分析法进行了稳定性判别。在土洞中充填砼,然后采用压力灌浆,灌浆所采用的水灰比为1∶1~1∶1.5,灌浆压力一般为0.15~0.30 MPa,地基处理效果好。     

Weed manipulation for insect pest management in corn

Populations of insect pests and associated predaceous arthropods were sampled by direct observation and other relative methods in simple and diversified corn habitats at two sites in north Florida during 1978 and 1979. Through various cultural manipulations, characteristic weed communities were established selectively in alternate rows within corn plots.Fall armyworm (Spodoptera frugiperda J. E. Smith) incidence was consistently higher in the weed-free habitats than in the corn habitats containing natural weed complexes or selected weed associations. Corn earworm (Heliothis zea Boddie) damage was similar in all weed-free and weedy treatments, suggesting that this insect is not affected greatly by weed diversity. Only the diversification of corn with a strip of soybean significantly reduced corn earworm damage.In one site, distance between plots was reduced. Because predators moved freely between habitats, it was difficult to identify between-treatment differences in the composition of predator communities. In the other site, increased distances between plots minimized such migrations, resulting in greater population densities and diversity of common foliage insect predators in the weed-manipulated corn systems than in the weed-free plots. Trophic relationships in the weedy habitats were more complex than food webs in monocultures.Predator diversity (measured as mean number of species per area) and predator density was higher in com plots surrounded by mature, complex vegetation than at those surrounded by annual crops. This suggests that diverse adjacent areas to crops provide refuge for predators, thus acting as colonization sources.     

回采工作面瓦斯涌出量遗传投影寻踪回归预测

为快速、准确预测回采工作面瓦斯涌出量,基于投影降维思想,建立一种遗传算法(GA)投影寻踪回归预测方法。选取煤层瓦斯原始含量、埋藏深度、煤层厚度、煤层倾角、工作面长度、推进速度、采出率、临近层瓦斯含量、临近层厚度、临近层层间距、岩层岩性、开采深度作为评价因子,对某矿15个学习样本进行训练,建立GA投影寻踪回归预测模型。利用该矿3个实测样本对模型进行检验,并与主成分分析和BP神经网络方法结果进行对比。研究表明:利用GA投影寻踪回归预测回采工作面瓦斯涌出量,平均误差为3.43%,最大误差为5.7%,精度优于其他2种方法。     

Research on whole life cycle carbon emission model of typical buildings

Based on the theory of life cycle assessment (LCA), this article analyzes the influence factors on carbon emissions from residential buildings. In the article, the life cycle of residential buildings has been divided into five stages: building materials production period, construction period, operation and maintenance period, demolition period, and solid waste recycle and disposal period. Based on this definition, the authors provide a theoretical model to calculate carbon emissions of residential building life cycle. In particular, the factor of human activities was introduced in the calculation of carbon emissions from the buildings. Furthermore, the authors put forward a model for calculation with the unit of carbon emissions for per-capita living space.     

《京都》15年后:分阶段减排政策与“绿色悖论”问题

低碳经济的政策分析,通常囿于单一国家层面的局部均衡结果,较少考虑到全球整体行动的外部影响,但从《联合国气候变化框架公约》建立以来的全球一致减排行动,却产生了一些意料之外的负面效果。本文通过梳理《京都议定书》签订以来,全球低碳经济合作中遇到的新挑战,以及碳交易市场的建设状况,采用制度分析与新古典框架下的市场均衡分析方法,讨论了全球一致减排行动所触发的"绿色悖论"问题。研究发现,造成"绿色悖论"的主要原因,一方面是由于国际合作存在制度设计上的缺陷,《京都议定书》及其关键性的附件一,将重点放在如何限制发达工业国的减排设计上,但却忽视了发展中国家在协议期内有可能出现的增排问题,以及发达国家向发展中国家污染转移的碳泄漏等问题;另一方面,当对不可再生资源的使用征税、以及对其替代品进行补贴时,将会导致在当前期对于化石能源的加速开采,并可能导致对同时期的化石燃料替代品的其他可再生资源的开采速度也大幅度加快,造成了在双重加速开采下的全球绿色福利损失以及CO2排放量的急剧升高,化石能源消费与温室气体排放面临到比协议签署前更为严峻,甚至与全球合作减排框架的设计初衷相悖的结果。研究结果表明,非全局性的减排公约和分阶段的减排政策,是造成"绿色悖论"现象的重要条件,缺少了大量发展中国家和一些重要工业国的缔约,使得负面的环境外部性难以克服;同时,减排任务和责任有所区别的分阶段设计,会把在未来行动期内可预见到的更高地化石能源使用成本转嫁到当前的行动期,造成短时间内资源与环境的迅速破坏。但本文的研究也表明,社会最优经济与对可再生能源进行补贴是克服"绿色悖论"现象的两条可行路径,且需要有与其相匹配的政府政策的支持。由此,本文的主要政策建议是,中国需要加强在国际气候公约中的影响力,提升自身话语权;以碳税政策作为发展低碳经济制度设计的主要政策工具;加快技术进步、提高能源使用效率,对于可再生能源研发进行补贴;根据国情不断优化碳税税率,并适时调整与其相匹配的新能源补贴等相关政策。