Refuge‐Effect Hypothesis and the Demise of the Dodo

The Dodo was last sighted on the inshore island of Ile d'Ambre in 1662, nearly 25 years after the previous sighting on the mainland of Mauritius. It has been suggested that its survival on the inshore island is representative of the refuge effect. Understanding what constitutes significant persistence is fundamental to conservation. I tested the refuge‐effect hypothesis for the persistence of the Dodo (Raphus cucullatus) on an inshore island beyond that of the mainland population. For a location to be considered a refuge, most current definitions suggest that both spatial and temporal isolation from the cause of disturbance are required. These results suggest the island was not a refuge for the Dodo because the sighting in 1662 was not temporally isolated from that of the mainland sightings. Furthermore, with only approximately 350 m separating Ile d'Ambre from the mainland of Mauritius, it is unlikely this population of Dodos was spatially isolated. Hipótesis del Efecto Refugio y la Desaparición del Dodo     

A unique intelligent approach for forecasting project completion time in oil refineries

This study presents a hybrid approach for accurate forecasting of project completion time with noisy and uncertain safety factors in oil refineries. The hybrid approach is based on artificial neural network (ANN), fuzzy mathematical programming (FMP) and conventional regression. Three indictors, namely, number of occupational injuries, number of employees and ratio of maximum useful hours over useful hour per month are considered as inputs. Also, project completion time is considered as the main output. To achieve the objective of this study, five sets of data with respect to oil refinery construction projects in various cities of Iran are collected and analyzed through statistical methods. It is shown that for the actual case of this study, ANN presents lowest mean absolute percentage error (MAPE). Also, analysis of variance (ANOVA) is used to verify and validate the results of this study. This is the first study that presents a hybrid approach for accurate estimation and forecasting of project completion time with complex, noisy and uncertain occupational factors.     

Quantifying parameter uncertainty in a coral reef model using Metropolis-Coupled Markov Chain Monte Carlo

Coral reefs are threatened ecosystems, so it is important to have predictive models of their dynamics. Most current models of coral reefs fall into two categories. The first is simple heuristic models which provide an abstract understanding of the possible behaviour of reefs in general, but do not describe real reefs. The second is complex simulations whose parameters are obtained from a range of sources such as literature estimates. We cannot estimate the parameters of these models from a single data set, and we have little idea of the uncertainty in their predictions.We have developed a compromise between these two extremes, which is complex enough to describe real reef data, but simple enough that we can estimate parameters for a specific reef from a time series. In previous work, we fitted this model to a long-term data set from Heron Island, Australia, using maximum likelihood methods. To evaluate predictions from this model, we need estimates of the uncertainty in our parameters. Here, we obtain such estimates using Bayesian Metropolis-Coupled Markov Chain Monte Carlo. We do this for versions of the model in which corals are aggregated into a single state variable (the three-state model), and in which corals are separated into four state variables (the six-state model), in order to determine the appropriate level of aggregation. We also estimate the posterior distribution of predicted trajectories in each case.In both cases, the fitted trajectories were close to the observed data, but we had doubts about the biological plausibility of some parameter estimates. We suggest that informative prior distributions incorporating expert knowledge may resolve this problem. In the six-state model, the posterior distribution of state frequencies after 40 years contained two divergent community types, one dominated by free space and soft corals, and one dominated by acroporid, pocilloporid, and massive corals. The three-state model predicts only a single community type. We conclude that the three-state model hides too much biological heterogeneity, but we need more data if we are to obtain reliable predictions from the six-state model. It is likely that there will be similarly large, but currently unevaluated, uncertainty in the predictions of other coral reef models, many of which are much more complex and harder to fit to real data.     

浑太河流域氮磷空间异质性及其对土地利用结构的响应

利用2009年8月和2010年6月浑太河流域河流水体采样数据,结合GIS技术和地统计学方法,分析了汛期TN(总氮)、NH₄+-N(氨氮)、NO₃--N(硝酸盐氮)、TP(总磷)和PO₄3-(磷酸盐)在地表水体中的空间变异特征,并探讨了流域尺度上土地利用对氮磷营养物质的影响. 结果表明:NH₄+-N、PO₄3-和TN均受到结构性因素的影响,表现出一定空间相关性变异特征;NO₃--N和TP主要受到随机性因素的影响,表现出极弱的空间相关性变异特征. 汛期流域林地、农田和居民用地比例与氮素呈显著相关,农田和草地用地比例与氮磷均呈显著相关.可以初步推测,林地、农田和居民用地是控制氮素空间分异特征的结构性因素,农田和草地是控制磷素空间分异特征的结构性因素.      

简易喷淋在“三合一”场所消防整治中应用的思考

家庭作坊式或出租屋式的“三合一”场所投资少回报快,成为一些小型私营企业创业初期的首选,但“三合一”场所消防安全条件差火灾频发,尤其是导致人员伤亡的火灾长期高发不下。例举了近年来我国一些“三合一”场所的火灾案例,分析了我国各地采取的“三合一”场所消防安全整治的方法及效果。针对该类场所消防安全整治中难监管、易回潮的特点,提出了在“三合一”场所中推广应用简易自动喷淋系统,革新技防手段的措施,强调了应用简易自动喷淋系统在使用范围、自动报警、喷头选择方面应注意的事项。     

降雨资料时间序列长度对降雨侵蚀力平均值置信度的影响

降雨资料时间序列长度是计算多年平均降雨侵蚀力过程中的重要不确定性因素.论文以中国601个气象站1980-2009年逐月降雨资料为数据源,利用Wischmeier经验公式计算了各气象站逐年降雨侵蚀力(R因子),用简单随机抽样方法抽取样本容量分别为30 a、 20 a、 10 a和5 a 四种不同的R值样本,计算了R平均值相对允许误差10%和25%条件下抽样估计的置信度.结果表明:降雨资料的时间序列长度对R平均值的估计置信度有显著影响;R平均值置信度存在明显的地域差异,长江以南、 青藏高原东部以及河西走廊南部的祁连山地区置信度较高;在降雨资料有限的情况下,必须根据土壤侵蚀研究的精度要求分析R平均值的抽样误差及其置信度,以保证土壤侵蚀定量预报的客观性与准确性.     

A critique of the official report on the evacuation of the World Trade Center: continued doubts

This paper criticises the conclusions and the unanswered questions in the National Institute of Standards and Technology (NIST)'s official report on the evacuation of the World Trade Center in New York City, United States, on 11 September 2001. It reviews the extent to which the report disregards several conventional statistical methods and comments on the NIST's refusal to share the machine‐readable data file with the scientific community for replication and further analysis. Problems lie in the sampling methods employed, the treatment of missing data, the use of ordinary least squares (OLS) with binary dependent variables, the failure to document the scalability of the scales used, the lack of tests to check for constant error variance, and the absence of overall fit tests of the model. There are also conceptual and theoretical issues, such as the absence in the report of considerations of the influence of group‐level processes and their impact on the collective behaviour of evacuating collectivities.     

钻井井喷爆炸事故分析及对策

针对井喷爆炸事故造成的巨大经济和环境问题,从消除井场点火源出发,讨论了井喷发生后防止爆炸的问题。基于井喷爆炸事故统计信息,利用事故树法,分析了井场可能存在的点火源,在此基础上提出井场防止井喷爆炸的措施。分析发现井喷爆炸主要分布在井喷后小于5分钟和井喷后大于1小时时间段,点火源主要为井场存在的点火源和后续抢救工作时带入的点火源;井场点火源主要分为明火、电火花、撞击火花和静电火花,通过井喷爆炸事故统计分析,电火花和撞击火花同样应该引起重视。     

AOB溶解氧亲和力低于NOB条件下序批反应器中NOB淘汰的实现机制

经精确测定AOB和NOB的溶解氧半速度常数及其他动力学参数,研究在AOB溶解氧亲和力低于NOB条件下,在序批反应器中短程硝化实现机制.测得AOB和NOB的溶解氧半速度常数分别为0.46和0.14mg O₂/L.在这种条件下,AOB的最大比生长速率高于NOB是实现短程硝化的重要特点,测得的AOB和NOB最大比生长速率分别为0.65和0.45d^-1.两级硝化数学模拟的结果表明,在AOB的溶解氧亲和力低于NOB条件下,低溶解氧和高泥龄都不利于短程硝化实现,而较高溶解氧和低泥龄的组合条件有利于短程硝化实现.在序批反应中的实验结果验证了数学模拟结论的正确性.     

Performance and kinetics of iron-based oxygen carriers reduced by carbon monoxide for chemical looping combustion

Chemical looping combustion is a promising technology for energy conversion due to its low-carbon, high-efficiency, and environmental-friendly feature. A vital issue for CLC process is the development of oxygen carrier, since it must have sufficient reactivity. The mechanism and kinetics of CO reduction on iron-based oxygen carriers namely pure Fe₂O₃ and Fe₂O₃ supported by alumina (Fe₂O₃/Al₂O₃) were investigated using thermo-gravimetric analysis. Fe₂O₃/Al₂O₃ showed better reactivity over bare Fe₂O₃ toward CO reduction. This was well supported by the observed higher rate constant for Fe₂O₃/Al₂O₃ over pure Fe₂O₃ with respective activation energy of 41.1±2.0 and 33.3±0.8 kJ·mol⁻¹. The proposed models were compared via statistical approach comprising Akaike information criterion with correction coupled with F-test. The phase-boundary reaction and diffusion control models approximated to 95% confidence level along with scanning electron microscopy results; revealed the promising reduction reactions of pure Fe₂O₃ and Fe₂O₃/Al₂O₃. The boosting recital of iron-based oxygen carrier support toward efficient chemical looping combustion could be explained accurately through the present study.