基于心理感知的铁路综合客运枢纽客流疏解预警研究*

为解决铁路综合客运枢纽客流疏解预警忽略旅客心理感知与焦虑问题,基于状态焦虑问卷,定量描述旅客焦虑状态,通过引入心理测量学中积极率划分客流疏解等级阈值,确定枢纽客流疏解预警等级,构建以旅客感知疏解时间为预警指标的回归预测模型。研究结果表明:模型可定量预测枢纽站各种交通接驳方式客流的感知疏解时间,准确描述枢纽站预警等级,研究结果可为管理人员选择相应疏解措施提供依据。     

操作条件对膜生物反应器运行经济性的影响

以运行费用作为膜生物反应器(MBR)运行经济性的考核指标,建立了MBR运行费用的计算模型,重点考察了膜通量、曝气强度、抽停时间、混合液悬浮固体质量浓度等操作条件对MBR运行经济性的影响.结果表明,膜通量在临界值5 L/(m2·h)时运行费用处于最低值;曝气强度过高或过低都会使系统运行费用增加,而经济曝气强度(气水比)为30:1;当抽吸时间≤12 min、停抽时间≥3 min时,运行费用变化缓慢,但抽吸时间或停抽时间超过临界值后,运行费用迅速上升;混合液悬浮固体质量浓度高于5.0 g/L时,运行费用随混合液悬浮固体质量浓度增加迅速递增.工程运行表明,运行费用模型预测值与实际值具有较好的一致性.     

Upscaling heterogeneity in aquifer reactivity via the exposure-time concept: inverse model

A novel inverse technique is proposed to quantitatively characterize macroscopic variability in aquifer reactivity in a Lagrangian representation. Reactivity heterogeneity is expressed in terms of distributions of flux over cumulative time of exposure of the solution to reactive surface area, termed here 'cumulative reactivity'. In cases involving single aqueous species the combined effects of physical and reactivity heterogeneity on reactive solute transport can often be established and further investigated through joint distributions of flux over travel time and cumulative reactivity. The inverse technique requires the breakthrough curve of a passive tracer to determine the distribution of flux over travel time, and additional breakthrough curves of reactive tracers provide additional moments of the distribution of flux over cumulative reactivity given travel time. Thus breakthroughs of one passive and two reactive tracers can provide the mean and variance of the distribution of flux over cumulative reactivity. This Lagrangian characterization is achieved with knowledge of the types of reactive surfaces present, but not their spatial locations. The distributions can subsequently be applied via forward modeling using the same technique to predict breakthrough curves of other solutes undergoing first-order reactions in similar physically and chemically heterogeneous configurations.     

Toxicity of Heavy Metals on Scenedesmus quadricauda (Turp.) de Brébisson in Batch Cultures (7 pp)

Background Aquatic environments are often exposed to various pollutants like heavy metals that are released from industrial, agricultural and domestic wastes. Emissions of heavy metals can then enter all ecosystems and bring about severe problems in plants, especially algae depending on the concentrations of a given element. The objective of the investigation presented is to detect toxic effects due to some heavy metals in the biomass of green alga Scenedesmus quadricauda. Methods All experiments were conducted with axenic cultures of the green alga Scenedesmus quadricauda (Turp.) de Brebisson (Chlorococcales, Chlorophyta). The cultures were grown in Chu-no.10 medium, and optimum physical and chemical growth conditions were provided to get higher growth rates and lower doubling times of cells. Growth of the micro algal cultures was measured on a daily schedule by counting cultures and determination of chlorophyll-a. The sterile-filtered heavy metal concentration solutions (Cd, Pb and Cu) were prepared and added as stock solutions of their salts (CdCl2*2.5 H2O, Pb(NO3)2*H2O and CuSO4*5 H2O). Results and Discussion The growth decreased gradually with the alga exposed to Cd at 0.05, 0.1, and 0.5 mg/L in comparison with the control whereas 1 mg/L Cd2+ had a clearly destructive effect. The growth was decreased with Pb at 15, 20 and 25 mg/L gradually, while at 30 mg/L the effect was more pronounced. When Cu was used, the growth was increased gradually at 0.5, 1 and 1.5 mg/L and vice versa at 2 mg/L. Conclusion There were differences in toxic effects of the metals with different metal as well as their concentrations and the time of exposure.     

我国耕地资源数量安全的时空差异分析

耕地资源数量安全是耕地资源安全非常重要的组成部分，它受到资源禀赋、经济发展水平、管理和政策等因素的影响。本文在分析耕地资源数量安全影响因素的基础上，构建其评价指标体系，并对我国耕地资源数量安全的时空差异规律进行了分析，结果表明。自改革开放以来，我国耕地资源数量安全状况呈先增后减的变化趋势；从安全水平的区域分布来看，北部和西部省份的安全水平普遍高于东部和南部省份，同时发现，区域安全水平与经济发展水平呈负相关关系。     

区域二氧化硫控制优化模型研究

传统的区域二氧化硫控制优化都是基于损害函数法和环境标准化法的。本文在分析比较了传统二氧化硫污染控制战略优化中的损害函数法和环境标准化法各自的优点与局限的基础上。建立了基于时间序列决策的整数规划优化模型。这一理论模型更好地描述了控制战略实施的过程。把时间作为模型优化的一个因子。这种基于时间序列的过程充分考虑了货币的时间价值。并能分析这些时间价值对二氧化硫污染控制战略的动态过程影响。本文的模型是更加符合现实的情况。它对于区域二氧化硫控制的中长期决策优化显得更为有效和准确。     

激光质谱法对机动车尾气中污染物的测量

本文详细介绍了一种全新的污染物测试方法———激光质谱法的原理和特点。我们应用这一方法对机动车尾气进行了初步探测 ,得到了 2 6 6nm激光作用下汽车尾气的激光电离质谱图 ,并对摩托车发动机运行状态与苯系列污染物排放量之间的关系进行了初步的在线测量     

人口统计的时空分析

本文以国际和国内人口统计的空间分析实验和动态分析为案例 ,阐述人口统计的科学分析方法及其在国民经济建设、城市化建设与国家安全等诸多方面的重要意义 ;指出“格网”数据库作为一种中间载体 ,有利于卫星遥感象元与人口数据的空间数据融合 ,有利于认识人口动态变迁的规律     

水力停留时间对复合式厌氧折流板反应器乙醇型发酵制氢系统的影响

水力停留时间(HRT)是厌氧生物制氢工艺的重要工程参数.以红糖废水为底物,研究了HRT对复合式厌氧折流板反应器(HABR)作为乙醇型发酵制氢系统产氢效能的影响.结果表明,在设定的8~36 h范围内的5个HRT中,当HRT为12 h时,HABR制氢系统的效果最佳,产氢速率为13.86 mmol·(h·L)-1,COD去除率为51.51%,五格室的pH值在4.22~4.47之间,液相主要产物为乙醇和乙酸,第1~5格室乙醇和乙酸的比值分别为1.90、1.94、1.80、1.77、1.91,最佳能量生产为11.11 kJ·(h·L)-1.     

滇池沉积物中主要污染物含量时间分异特征研究

基于滇池10个监测点(1991~2010年)表层沉积物中主要污染物(Cd、Cr、Cu、Hg、Pb、Sn、Zn、TP以及KN)含量数据,利用SOM自组织映射神经网络对污染物时间演变特征进行识别.将1991~2010年分为4个阶段,1991~1995年低含量阶段;1996~2001年高含量阶段;2002~2006年含量波动阶段;2007~2010年含量回落阶段.各沉积物中污染物的变化模式不尽相同,但各类重金属含量峰值多集中出现在1996~1999年、2005~2007年2个时间段内.在污染物含量变化的时序分析基础上,参考入湖污染负荷、污染源普查数据等相关资料,分析人类活动对滇池沉积物中主要污染物的影响,发现人类活动对沉积物中污染物含量变化的影响很大,在污染物排放量大的时期,沉积物中污染物含量也会随之出现明显升高,在采取污染控制及治理措施后,沉积物中污染物含量会随之下降.