船舶安全熵概念的提出及应用

船舶航行安全很大程度上取决于操作者对船舶航行过程中各种信息的把握,信息掌握的多少可作为衡量船舶安全的一个标准。把船舶航行链分为5种信息处理过程,利用信息熵的原理,提出船舶安全熵的概念,并建立了数学模型。根据船舶航行信息过程的具体因素,建立船舶航行安全评价指标体系;利用熵权法确定5种信息单元及其安全因素权重,对船舶航行的安全熵进行计算,可根据评价模型对船舶安全进行有效评价。利用渤海湾船舶M进行验证,其结果发现船员素质安全熵最大。船舶安全熵方法是对船舶安全评估的一种新探索。     

基于模糊聚类的马氏链模型在交通事故预测中的应用

运用模糊聚类分析方法,借助于MATLAB软件,对中国31个地区交通事故的危害程度进行动态分类和综合评价。根据中国1999—2005年31个地区的交通事故4个指标和5个社会经济因素数据,把31个地区分为3类,即轻灾区、较重灾区、重灾区;其中浙江、福建与宁夏的交通事故危害严重,上海、北京与天津的交通状况正在好转,这与客观实际符合。根据模糊聚类的结果,求得交通事故状态转移概率矩阵,利用马氏链模型可预测未来31个地区的交通事故发展趋势。     

STOCHASTIC MODELING OF MONTHLY AND DAILY RAINFALL SEQUENCES1

ABSTRACT: A monthly model and two daily models (I and II) are presented for the purpose of generating monthly and daily rainfall sequences in the Quae Yai river basin in Thailand. Performance of the models are evaluated by comparing the statistical parameters of the generated sequences with those from historical data. For monthly generation, Thomas-Fiering model worked satisfactorily in spite of the monthly correlations being weak, if any. Daily Model I, which assumes no persistence between daily rainfall amounts within the wet spells, could not preserve some important parameters regardless of the simplicity in model construction. Application of multi-state transition probability matrix model gave good results, although the user has to modify some parameters looking at the performance of the model for each historical record.     

广州土壤中短链氯化石蜡的含量水平和分布特征

短链氯化石蜡(SCCPs)是一类新的持久性有机污染物(POPs),目前我国相关研究较少。为了解SCCPs在土壤中的污染现状和分布特征,测定了24个广州土样(含3个剖面采样点)中SCCPs的含量,分析了其同族体分布模式。结果表明:广州表层土壤中SCCPs的含量变化范围为6.8～541.2ng/g,均值为79.6ng/g;剖面土壤中SCCPs的含量范围为7.5～115.8ng/g,均值为33.1ng/g。不同类型土壤中SCCPs各同系物组分的分布模式相似,以碳原子数为10和11的Cl6-SCCPs/Cl7-SCCPs为主。     

Arsenic rich iron plaque on macrophyte roots - an ecotoxicological risk?

Arsenic is known to accumulate with iron plaque on macrophyte roots. Three to four years after the Aznalcóllar mine spill (Spain), residual arsenic contamination left in seasonal wetland habitats has been identified in this form by scanning electron microscopy. Total digestion has determined arsenic concentrations in thoroughly washed ‘root + plaque’ material in excess of 1000 mg kg⁻¹, and further analysis using X-ray absorption spectroscopy suggests arsenic exists as both arsenate and arsenite. Certain herbivorous species feed on rhizomes and bulbs of macrophytes in a wide range of global environments, and the ecotoxicological impact of consuming arsenic rich iron plaque associated with such food items remains to be quantified. Here, greylag geese which feed on Scirpus maritimus rhizome and bulb material in areas affected by the Aznalcóllar spill are shown to have elevated levels of arsenic in their feces, which may originate from arsenic rich iron plaque.     

震后灾害链生机制及其对汶川地震城镇重建的影响

汶川8级大地震对地表产生强烈扰动,导致次生山地灾害极度发育,影响到震后灾害的活动特征及其相应的减灾对策。震后松散固体物质急剧增加、流域微地貌变化明显(沟道堵塞严重)、水文变化利于侵蚀和洪峰,使得灾害群发链生:崩塌、滑坡→泥石流→堰塞湖→溃决洪水(泥石流),8月中旬灾区各地因强降雨而大规模爆发泥石流堵塞河道,洪水冲毁掩埋重建城镇,给地震重灾区造成巨大损失。从以汶川县映秀镇为例,在阐述灾害链研究成果的基础上,分析震后灾害链的形成条件、成灾过程以及对城镇重建居民点的危害特点,进而提出灾害防治措施,为灾后城镇建设防灾减灾提供参考建议。     

基于灰色-马尔科夫模型的我国能源消费结构优化调整

本文以我国1997—2010年的消费结构数据为基础,运用灰色-马尔科夫链模型对数据进行了分析和预测,然后通过MATLAB预测了我国未来十年的能源消费结构,结合我国政府承诺的非化石能源目标对模型预测结果做了进一步的修正,最后根据能源发展趋势给出了能源消费结构的优化策略。     

Method to analyze the regional life loss risk by airborne chemicals released after devastating earthquakes: A simulation approach

Widespread chemical plants render human life more vulnerable to major natural disasters such as earthquakes. Recognizing the potential cascading threats initiated by a devastating earthquake, a general methodology for assessing the life loss risks introduced by airborne hazardous chemical dispersion following seismically induced chemical release (SICR) was proposed. With a 600 km × 600 km region in North China as a demonstrative study area, the dispersion of ammonia released from multiple relevant chemical plants that were supposed to be damaged by a devastating earthquake was simulated in a probabilistic manner. Using an ammonia toxicity-fatality relationship and its toxicity concentration threshold, regional life loss and spatial spread were evaluated. The life loss risk was found to be non-prominent but would be very contingent on unfavorable meteorological conditions. Non-parametric correlation analysis revealed that the respective effects of meteorological mixing parameters on the risk exhibit new features in a disaster context, that is, stronger mixing would cause elevation of risk in a region. This preliminary research implied that the risk of chemical-induced life loss after a devastating earthquake deserves attention and a thorough uncertainty evaluation in the future.     

地铁运营突发事件应急响应模式的马尔科夫链分析

为研究城市轨道交通网络化运营线路的风险传导规律和耦合关系,构建基于随机Petri网的同构马尔科夫链模型。通过模型分析突发事件应急响应模式中线路之间的相互影响,以及各线路启动突发事件应急响应模式对整个系统稳态的影响。结果表明,用该模型可从数学上研究城市轨道交通运营线路之间的传导规律和耦合关系,找出影响整个应急指挥系统效率的关键因素,最终提高地铁应对突发事件的能力。     

食物链途径人体健康风险评估的关键内容探讨

食物是人类生存的重要保障,食品安全事关人类生命健康.食品污染始于农田耕地,还包括生产制造、包装、贮存、运输、加工等环节,每个步骤处理不当都可能发生食品安全问题.农田为食物来源的基石,是空气、水体中污染物的汇,随着城市的扩张,人类经济活动导致农田污染加剧.人类从食物中摄取污染物与经口、呼吸、皮肤的途径一样,是人体健康风险评估不可缺少的考量因素之一.我国对食品安全非常重视,2010年1月原卫生部根据《食品安全法》建立《食品安全风险监测管理规定》和《食品安全风险评估管理规定》(试行),这两份文件涵盖了从土壤到餐桌一系列的风险过程.但由于每个过程产生的原因、污染物影响机制均不同,规定离具体实际应用目标还很远.2014年环保部以保护生态环境,保障人体健康为根本,为加强污染场地环境保护监督管理,规范污染场地人体健康风险评估,发布了《污染场地风险评估技术导则》,该文建立了土壤污染造成人体健康风险评价的操作方法.然而导则考虑了经口、皮肤、呼吸及饮用地下水等9种暴露途径和评估模型,唯独缺少经食物链暴露这一重要途径的相关内容.本文以英、美两国食物链途径的场地污染风险评估为依据开展了详细探讨,深入分析了评估程序中关于土地利用方式的分类、目标人群暴露特征、污染物在食物链中传输路径、模型选取及暴露参数等内容,以期为我国制定《食物链暴露途径风险评估导则》提供一定的参考依据和指导方法.