光学迷宫对飞机货舱感烟探测器响应性能的影响

针对飞机货舱火灾的探测延迟性问题,探讨了光学迷宫对点型光电感烟探测器响应性能的影响,实验研究了点型光电感烟探测器在有、无迷宫两种情况下烟雾探测的响应过程,对比分析了不同烟量时迷宫的作用,并提出探测器迷宫结构的改进设计思路。实验结果表明,在探测器响应过程中,有光学迷宫的探测器烟雾浓度波动幅度较小,迷宫对烟气有滞留作用,提高了探测器的稳定性;但迷宫会使探测腔室的烟雾浓度明显滞后且低于腔外,增大了探测器的迟滞时间,烟雾浓度较低时这种迟滞影响更为明显,严重影响货舱火警探测器的灵敏度。     

认知资源对公众城市气象灾害防御支付意愿的影响研究#br# ——基于南京市暴雨灾害防御的实证

城市气象灾害防御措施的改进是防灾减灾的有效手段，但如何在辨识公众支付意愿的基础上，构建多方成本分担的灾害防御制度是解决问题的关键。从成本分担的视角出发，以南京暴雨灾害防御为例，分析公众对增强型城市气象灾害防御的支付意愿及认知资源在其中的重要作用。通过构建由Probit模型和有序Probit模型组成的递归混合模型，探讨认知资源和经济资源在公众支付决策中的重要性。研究表明:认知资源的作用十分明显，且随着公众对暴雨灾害风险感知、防御措施了解程度、防御制度认可程度的提高，公众支付意愿越强。而暴雨灾害风险感知又受到灾害趋势认知和经历的共同影响，这两个变量分别影响风险感知的广度和深度，但受教育程度对风险感知深度的影响并不显著。核心建议是从满足公众对城市暴雨灾害风险、防御措施、灾害趋势等知识的需求，政府应该加强暴雨灾害科普宣传的主动性、提升主管和协同部门的公信力；规范科普知识内容、拓宽科普渠道。     

纳米材料对环境中微生物活性的影响研究

研究纳米材料对环境中微生物细胞活性的影响可为纳米材料的生物安全性评价提供一定的理论基础.以大肠杆菌和枯草芽孢杆菌为受试生物,采用电导率仪测定细菌培养液电导率变化,分别研究了纳米TiO2、纳米ZnO、纳米Fe3O4、纳米SiO2、纳米二氧化钛载银、纳米磷酸锆载银、纳米棕色银对细菌细胞膜通透性的影响.结果表明,纳米材料对革兰氏阳性枯草芽孢杆菌细胞活性影响更大;同种纳米材料,粒径越小,对细菌的细胞活性影响越强;对细菌细胞活性影响最大的是纳米棕色银,对细菌细胞活性影响最小的是纳米SiO2和Fe3O4.     

渭河陕西段潜流带沉积物重金属变化初步分析

为厘清潜流带沉积物重金属时空变化及与水量交换、沉积物颗粒结构间的关系,于2013年春夏两季对渭河陕西段5个研究断面66个测试点位沉积物的野外原位渗透系数、颗粒粒径、重金属含量进行分析.结果表明:影响渭河沉积物渗透系数的主要因素是沉积物粒径,同时沉积物垂向分层、排列组合也影响其渗透性能;沉积物重金属Cu、Zn、Pb、Cd质量分数在垂向上不同深度其含量大小不同,在时间上总体呈现春季夏季,富集系数(EF指数)分析结果显示春季Cu、Zn(除华县)、Pb(除眉县)、Cd富集严重且主要受人为输入源影响,夏季除Cd元素外,Cu、Zn、Pb的EF值均1.5,说明其含量主要来源于地壳和岩石圈的自然风化过程;Pearson相关分析发现粘土与粉砂(粒径0.075 mm)百分比与沉积物重金属质量分数呈弱相关,重金属粒径效应不显著,粒径不是控制重金属含量的主要环境影子;对单一重金属垂向不同深度含量进行相关性研究发现除Cd外,其余3种重金属在垂向上的相关系数均0.5(p0.01),说明单一重金属在垂向上具有同源性且存在相互迁移与转化.     

重碳酸型地下水矿化度测定方法的探讨——以洛阳市浅层地下水为例

矿化度是地下水化学成份测定的重要指标，在环境监测中，用重量法测定矿化度是目前普遍采用的方法。其缺点主要为费时，繁琐，耗电。本文通过测定洛阳市地下水的电导率，分析对比电导率与矿化度的关联，并进一步用回归方程确定电导率与矿化度之间的数量关系，探索出用电导率法间接测定地下水矿化度，具有快速，经济，准确的优点。     

STREAMBED HYDRAULIC CONDUCTIVITY FOR RIVERS IN SOUTH‐CENTRAL NEBRASKA1

ABSTRACT: This paper presents hydraulic conductivities of streambeds measured in three rivers in south‐central Nebraska: the Platte, Republican, and Little Blue Rivers. Unlike traditional permeameter tests in streams that determine only the vertical hydraulic conductivity (K_v), the extended permeameter methods used in this study can measure K in both vertical and horizontal as well as oblique directions. As a result, the anisotropy of channel sediments can be determined from streambed tests of similar sediment volumes. Sandy streambeds with occasional silt/clay layers exist in the Republican and Platte Rivers. The average K_v values range from about 15 to 47 m/day for the sandy streambed and about 1.6 m/day for the silt/clay layers. Statistical analyses indicated that the K_v values of sand and gravel in the Platte and Republican Rivers essentially have the same mean; but the K_v values from the Little Blue River have a statistically different mean. K_v is about four times smaller than the horizontal hydraulic conductivity (K_h) for the top 40 cm of sandy streambed. Measured K_h values of the sandy streambed are in the same magnitude as the K_h of the alluvial aquifer determined using pumping tests. The smaller K_v value in the whole aquifer is the result of interbedded layers of silt and clay within the sand and gravel sediments.     

EVALUATION OF A STREAM AQUIFER ANALYSIS TEST USING ANALYTICAL SOLUTIONS AND FIELD DATA1

ABSTRACT: Considerable advancements have been made in the development of analytical solutions for predicting the effects of pumping wells on adjacent streams and rivers. However, these solutions have not been sufficiently evaluated against field data. The objective of this research is to evaluate the predictive performance of recently proposed analytical solutions for unsteady stream depletion using field data collected during a stream/aquifer analysis test at the Tamarack State Wildlife Area in eastern Colorado. Two primary stream/aquifer interactions exist at the Tamarack site: (1) between the South Platte River and the alluvial aquifer and (2) between a backwater stream and the alluvial aquifer. A pumping test is performed next to the backwater stream channel. Drawdown measured in observation wells is matched to predictions by recently proposed analytical solutions to derive estimates of aquifer and streambed parameters. These estimates are compared to documented aquifer properties and field measured streambed conductivity. The analytical solutions are capable of estimating reasonable values of both aquifer and streambed parameters with one solution capable of simultaneously estimating delayed aquifer yield and stream flow recharge. However, for long term water management, it is reasonable to use simplified analytical solutions not concerned with early‐time delayed yield effects. For this site, changes in the water level in the stream during the test and a varying water level profile at the beginning of the pumping test influence the application of the analytical solutions.     

峨眉山降水电导率变化规律初探

本文通过对峨眉山山顶和山下１９８６年～１９９５年降水电导率变化规律的分析发现,其两地电导率与降雨量及降水酸度存在一定的关系,也存在一定的差异。这差异表明山顶降水酸度来源于中长距离的传输     

水中全盐量的电导法测定

本文介绍了用电导法测定水样中全盐量的新方法，与经典的重量法相比，具有快速、简便、准确的优点。经对水样分析，结果令人满意     

浅层地下水矿化度测定方法的探讨

矿化度是地下水化学成分测定的重要指标 ,在环境监测中 ,用重量法测定矿化度是目前普遍采用的方法。其缺点主要是费时、繁琐、耗电。本研究通过测定洛阳市地下水的电导率 ,分析对比电导率与矿化度的关联 ,并进一步用回归方程确定电导率与矿化度之间的数量关系 ,探索出用电导率法间接测定地下水矿化度 ,具有快速、经济、准确的优点