地震减灾体系中的区域联防问题

地震灾害是我国主要的自然灾害之一。现阶段,减轻地震灾害的主要途径是在努力提高地震监测预报水平的基础上,发挥政府、社会和地震科技队伍三方面的作用,坚持以预防为主,建立地震减灾工作体系,走综合减灾的道路。行使政府职能是地震减灾工作体系的中心环节,职能的行使以一级政府的行政管辖范围为“边界”。但我国大陆地区已发生的大震和当前的重点监视防御区多分布于二省、三省或更多省市交界地区。突破行政区划,在地震活动区、危险区周围协调地开展监测、预报、宣传、防御工作是当前进行防震减灾战略布局所必需。地震科学发展的“跨”行政区划和政府行政职能的严格区划性的尖锐矛盾,有必要提出地震减灾中的区域联防问题,本文是有关这个问题的分析与建议。     

基于二维Gumbel分布的长距离输水系统水文风险评估

在现行的水文风险组合计算中,往往需要对非正态分布的水文变量进行正态化处理,这必然引起畸变,从而影响分析计算结果的准确性。针对这一问题,在以往的研究基础上,根据Ditlevsen界限,进一步建立了基于二维Gumbel分布的长距离输水系统的综合水文风险评估模型,从而巧妙地解决了串联系统风险计算中如何建立n维联合概率分布函数的难题。并以南水北调中线工程河北省段的21条主要河流为例,分析了采用Gumbel联合分布来研究降雨量或洪水的联合分布特征的可行性,进行了实际水文概率的组合计算,结果表明南水北调中线工程河北省北段的综合防洪风险是3．1％,其防洪安全是有保证的。     

长江中下游地区气象干旱特征

长江中下游地区是中国重要的粮食生产基地,在当前全球气候变化的背景下,旱灾将直接影响该区域人民的生产生活和国家粮食安全。基于标准化降水指数（SPI）,采用1961-2015年的中国地面降水月值0.5°×0.5°格点数据集,通过游程理论定义气象干旱事件,并获取了描述干旱事件特征的三个变量：干旱历时、干旱烈度和烈度峰值。指数函数和伽马函数分别用来拟合干旱历时和干旱烈度的边缘分布,Clayton Copula函数用来构建干旱历时和干旱烈度的联合分布。在此基础上,分别用常规单变量和基于Copula双变量的频率分析方法探讨55年来长江中下游地区干旱事件在不同时间尺度下的空间特征。结果表明：（1）不同时间尺度下,长江中下游地区的干旱特征空间格局存在一定的差异,最严重的干旱主要发生在长江下游地区; （2）不同时间尺度的干旱历时和干旱烈度均呈正相关,即较严重的干旱事件通常持续更长的时间;（3）鄱阳湖流域和长江干流下游的北部干旱风险较高,而陕西南部、河南南部、湖北大部和湖南的中北部干旱风险较低。研究结果可为长江中下游地区水资源的科学管理和干旱灾害的风险评估提供理论依据。     

SDS与取代芳烃多元混合体系联合毒性作用研究

测定了阴离子表面活性剂十二烷基硫酸钠(SDS)和3种取代芳烃苯酚、硝基苯、甲苯对发光菌的单一毒性,以及等浓度配比下SDS与3种取代芳烃二元、三元及四元混合体系的联合毒性效应,并基于常见的4种联合作用评价方法,对混合体系的联合毒性作用进行了评价研究.结果表明,4种不同的评价方法对SDS与苯酚、甲苯和硝基苯的联合效应评价结果具有较好的一致性,即在以SDS为底物的混合体系中,除SDS与硝基苯联合毒性表现为弱拮抗作用外,其它的二元、三元及四元混合体系的毒性均表现为不同程度的协同作用,且甲苯的协同程度最强.在选择的联合研究体系中,以毒性单位法获得参数的数值较大,判定灵敏度较高.根据发光菌发光原理、SDS的分子结构特征和芳烃类化合物取代基的不同,可对联合毒性作用的机理进行初步探讨.     

Experimental study on sediment-copper distributions in hyper-concentrated turbulent solid-liquid system

This study presents a special problem on vertical distribution for sediment and copper in hyper-concentrated turbulent solid-liquid system that is essentially different from the ordinary low-concentrated turbulent system. A resonance type turbulent simulation equipment is used for the experimental study in which a vertically uniform turbulent field of the mixture of loess and water is produced in a testing cylinder with a grille stirrer that moves up and down harmoniously with varying vibration frequencies, in order to compare the variations of the vertical profiles of sediment and copper in low- and hyper-concentratod solid-liquid system, different scenarios for input sediment content ranging from 5 to 800 kg/m^3 was considered in the experimental studies. It was found that solids copper content increases with input sediment content, So, and reaches its peak as So goes to 10 kg/m^3 and then decreases rapidly with increasing input sediment content. Such a behavior is possibly resulted from the joint effect of the specific adsorption of copper on loess, precipitation of carbonate and hydroxide of copper due to high carbonate content in the loess and the so-called ＂particulate concentration effect＂ due to the present of the sediment variation in water. The vertical sediment concentration distribution resulted from the uniform turbulence is generally uniform, but slight non-uniformity does occur as sediment concentration exceeds certain value. However, the vertical concentration distributions of soluble copper seem not to be affected much by the variation of sediment concentrations.     

新疆极端降水概率分布特征的时空演变规律

依据新疆地区53个雨量站1957-2009年日降水资料,根据研究需要,定义了8个极端降水指标。运用K-S法确定降水指标最适概率分布函数,确定10年一遇极端降水量值;在此基础上,采用Copula非参数估计方法,通过Akaike information criterion(AIC)法确定两降水指标联合分布函数,系统分析1980年以后极端降水单变量极值及降水极值二维联合概率分布特征变化的时空演变特征,研究结果表明:①新疆有湿润化趋势,北疆湿润化趋势比南疆显著;②从降水天数和极端降水天数角度来看,新疆极端强弱降水同时出现的概率减小,从极端降水雨量和强度来看新疆中部、南疆西部、北疆东部及北部极端强弱降水同时出现的可能性减小,而天山西部与南疆北部的可能性增加;③1980年后新疆地区发生涝的概率增大,发生旱的概率减少。     

广东四大区域污染过程特征与影响天气型分析

根据广东统计年鉴将广东省划分为粤东、粤西、粤北、珠三角四大区域,利用广东省101个环保国控站点2014—2016年期间的AQI六要素与广东省86个地面气象观测站的逐日能见度、相对湿度等资料,在对"区域污染过程"进行定义的基础上,分区域诊断典型污染天气过程,并对影响天气型及特征进行分析.结果表明:广东省四大区域污染过程具有显著协同性,区域污染可归类为6种影响天气型.量化分析表明区域污染过程与区域灰霾过程基本吻合,PM_(2.5)日均最大值均达到中度污染及以上(115μg·m~(-3)).整体区域污染过程影响天气型分类统计表明:珠三角和非珠三角PM_(2.5)易污染天气型中冷高变性出海形势占比超5成;珠三角O_3易污染天气型中副高、台风外围及两者叠加型占比超6成;珠三角NO_2易污染天气型中冷高出海型占比近7成.重污染影响天气型统计表明:区域PM_(2.5)重污染过程主要影响天气型为冷高压变性出海型;区域中度至重度O_3污染过程(集中在珠三角)主要影响天气型为副高、台风外围及两者叠加型;就天气型特征而言,单纯副高控制形势下,副高异常强盛;单纯台风外围形势下,台风强度为强台风至超强台风;副高叠加台风时,华南上空为大陆副高控制.广东地区近年高PM_(2.5)(与低能见度)污染过程逐年减少,但全省臭氧污染呈增加态势,尤其珠三角区域中度至重度O3污染过程次数同比明显增加,极端过程出现概率加大,尤其在秋季副高异常强盛,同时叠加台风外围下沉气流时,可预先根据影响天气型预报,实施珠三角重点区域联防联控预案措施.     

Long-Term Population Changes of Native and Introduced Birds in the Alaka'i Swamp, Kaua'i

Abstract:  Within the last 30 years, five endemic bird species of the Alaka'i Swamp, Kaua'i, Hawai'i, have likely gone extinct. We documented population trends of the remaining avifauna in this time period to identify a common pattern in the Hawaiian Islands: decline of native species and expansion of introduced species. We conducted bird surveys over 100 km² of the Alaka'i and Kōke'e regions of Kaua'i in March–April 2000 to estimate population size, distribution, and range limits of seven native and six introduced forest birds. We compared the results with four previous surveys conducted over the last 30 years. Five of the seven native species we studied have fared well, maintaining sizeable populations (>20,000 individuals) and unchanged or increasing numbers. The endemic 'Akikiki ( Oreomystis bairdi ), however, declined from 6296 (SE ± 1374) to 1472 (SE ± 680) individuals and exhibited range contraction from 88 to 36 km². The 'I'iwi ( Vestiaria coccinea ) also experienced a decline and contraction, though not as severe. Populations of several introduced forest birds are increasing, but all species, excluding the Japanese White-eye ( Zosterops japonicus ), were at low numbers (<5,500 individuals in survey area). One introduced species, the Japanese Bush-Warbler ( Cettia diphone ) recently invaded, whereas another, the Red-billed Leiothrix ( Leiothrix lutea ), has been extirpated. Two hurricanes in the past 20 years appear to have most strongly affected nectarivores and may have contributed to the decline or extinction of several other species. Overall, native bird populations on Kaua'i have exhibited species-specific responses to limiting factors. Although most native populations appear stable, the extant native avifauna is vulnerable as a result of limited distributions and the potential for widespread habitat degradation.     

对水工构筑物设计的几点看法

探讨了水工构筑物设计中的地下水位确定、伸缩缝设置、总体布置及设计与施工配合等问题。设计在满足国家有关政策、规范要求的同时,要做到技术先进、安全适用、经济合理。     

矩形风管局部构件与直管段气溶胶粒子沉降速度比较分析

气溶胶是影响室内空气质量的重要因素之一,室外的气溶胶粒子通过风管系统进入室内,严重危害人们的健康.本文用滑石粉模拟气溶胶粒子,对矩形风管系统(材料为镀锌钢板)的直管段、渐缩段和风阀等3个位置,测定了气溶胶粒子在不同风速和粒径下的表面沉降速度,分析了它们之间的关系.结果表明,风管断面的沉降速度随风速和粒径的增加而增加;同一风管断面上底面的沉降速度最大,侧壁面次之,顶面最小;渐缩段底面、侧壁面和顶面的沉降速度均比直管段大,风阀断面的沉降速度明显高于直管段.研究表明,风管系统底面及局部构件是积尘的主要部位,也是风管系统清洗的重点.