交通事故的时间分布规律

交通事故已成为威胁人民生命、财产安全的社会公害之一。笔者利用国内外有关交通事故数据进行统计分析,对交通事故发生的时间特征进行研究,为改善交通安全状况提供理论基础。运用统计分析、对比分析方法,分析国外不同国家和我国交通事故年时间分布规律的波峰曲线,得出我国交通事故逐年上升的势头有望得到遏制,使人们对战胜交通事故灾害充满信心。分析交通事故小时时间分布曲线,得出交通事故高峰小时出现在交通量高峰小时之后,两者不重合,死亡高峰时段(危险时段)多发生在夜晚等结论。该结论对采取针对不同时间内降低交通事故的教育、管理、工程等安全对策具有实用价值。     

不同时间尺度气候变化的分维研究

探讨了从一维时间序列中提取气候分维的方法，计算了不同时间尺度气候变化的分数维，并讨论了维数与气候变化的相关系。     

地震活动趋势的多层递阶预报

多层递阶预报是动态系统的新型统计预报理论,由于它把动态系统看成是一个时变参数系统,因而与客观实际较为符合,预报误差也相对较小,利用它来预报一个地区未来的地震活动趋势,具有一定的实用价值。     

路面预防性养护时机确定方法探讨

介绍了路面预防性养护时机的确定方法 :应用行驶质量指数或破坏指数、基于时间或路况、效益费用评估、生命周期费用分析、决策树或决策矩阵、评分排序方法进行路面预防性养护时机的确定 ;挖掘了目前路面预防性养护时机选取方法中存在的不足。根据路面破坏的复杂性以及目前路面预防性养护时机选取方法的不足 ,提出应对措施 ,路面预防性养护时机研究应该在一个多标准、基于路面性能的基础上进行 ;在路面结构性能良好的情况下 ,基于预防性养护的路面功能性能衰变是进行路面预防性养护时机研究的关键     

江河防洪系统年超标洪水风险率模型研究

本文在考虑最近一次历史洪水发生时间这一因素下,提出了防洪系统年洪水风险率模型.模型反映了年洪水风险率随距己发生洪水的间隔时间递增的规律.最后对这种规律对防洪标准的影响进行了讨论.     

Lake management techniques in Florida,USA: Costs and water quality effects

Economic evaluations of restored or enhanced lakes in Florida indicated gravity drawdown was the least expensive action, whereas effluent diversion was 10,000 times more costly on a per hectare basis, with the other lake treatment costs occurring in the following order: gravity drawdown < grass carp introduction < mechanical drawdown < aeration < stormwater control = drawdown-dredging < effluent diversion. Within a particular treatment category, the costs spanned approximately one and one half orders of magnitude. Contrary to the abundant cost data, which permitted an economic analysis, inappropriate statistical design and lack of commitment toward sampling Florida's restored lakes undermines attempts to understand long-term water quality responses to various enhancement techniques. Using Lake Tohopekaliga as a case study, ordinary statistical tests produced contradictory and unreliable interpretations on the effectiveness of drawdown and phosphorus removal at sewage treatment plants in improving the trophic state index. This emphasizes the need for more robust statistical approaches and more detailed data collection in evaluating lake restoration activities It is unfortunate for Florida's lake restoration program that quantitative conclusions based on inferential statistics, replete with tests of assumptions, is limited to very few lakes     

环境影响评价中容易忽视的问题及处理方法

在环境影响评价过程中,经常会遇到一些简单却又很容易被忽视的问题,如水环境评价中的pH值、DO、大气环境影响预测中的取样时间等。如若处理不当将直接影响到环评报告书评价结论,只有掌握这些问题的处理方法,才能不断提高环评人员的业务水平和评价报告的质量。     

不同时间长度监测道路交通噪声比较

目前道路交通噪声的监测时间规定为20 min,监测工作量大。实验采用5 min测量与20 min测量进行比较,结果表明,2种时间测量的最终结果无明显差异。     

延长初发酵培养时间对大肠菌群结果影响分析

阐述了将《大肠菌群多管发酵法》(GB/T 4789.28-2003)初发酵时间24 h延长至48 h的原因,通过对139份不同种类样品进行大肠菌群总数检测,发现有12份样品增加了大肠菌群数,表明延长初发酵培养时间,可以增加迟缓发酵大肠菌群成员检出.指出迟缓发酵大肠菌群在44.5 ℃培养时,均无产酸产气现象,表明引起迟缓发酵的大肠菌群不属于粪大肠菌群成员.     

Vertical fluxes of aromatic and aliphatic hydrocarbons in the Northwestern Mediterranean Sea

Aliphatic and aromatic hydrocarbon fluxes were measured in time series sediment trap samples at 200 m and at 1000 m depths in the open Northwestern Mediterranean Sea, from December 2000 to July 2002. Averaged fluxes of n-alkanes, UCM and T-PAH₃₅ were 2.96 ± 2.60 μg m⁻² d⁻¹, 64 ± 60 μg m⁻² d⁻¹ and 0.68 ± 0.59 μg m⁻² d⁻¹, respectively. Molecular compositions of both hydrocarbon classes showed a contamination in petrogenic hydrocarbons well above the background levels of such an open site, whereas pyrolytic hydrocarbons stand in the range of other open Mediterranean locations. Fluxes displayed ample interannual and seasonal variabilities, mainly related to mass flux variation while concentration evolutions trigger secondary changes in pollutant fluxes. High lithogenic flux events exported particles with a larger pollutant load than biogenic particles formed during the spring bloom and during the summer. Sinking hydrocarbons were efficiently transported from 200 m to 1000 m.