河网水质模型研究进展

纵观水质模型的研究、应用及相关科学的发展,本文针对现有的水质模型做了分析评价,简要介绍了河网水质模型的未来研究趋势,并提出了几点建议。     

基于“反规划”视角的乡村旅游规划新途径探析

引入"反规划"思想,针对传统规划方法给乡村旅游带来的不利影响,强调"反规划"在乡村旅游规划中应用的必要性与可行性。通过与传统规划方法进行对比分析发现,当前乡村旅游规划中存在不少亟待解决的问题。同时,探析了"反规划"思想在乡村旅游规划中的运用,建立乡村旅游"反规划"发展模式为保障乡村旅游可持续性发展提供了理论依据。     

应用CALINE4模式估算机动车排放污染物的浓度——以济南市主干道为例

随着经济的快速发展,机动车排气污染已成为我国城市空气污染的重要来源,而且在一定时段,机动车排气污染已成为空气污染最主要的污染源之一。以济南市经十路为例,采用实地调查的方法,得出各时段的车流量,选用大气环评助手EIAA中的CALINE4模式对机动车尾气中的主要污染物CO、NOx、THC的排放浓度进行估算,得出3种污染物CO、NOx、THC最大值均出现在7:00—8:00之间,最小值均出现在12:00-13:00之间,排放强度由大到小为:CO、THC、NOx。     

沟谷泥石流运动过程模型试验

泥石流运动过程是泥石流运动力学核心内容之一.以新疆天山公路K630泥石流为原型,选取几何相似比1:650,推导了泥石流质量、固液两相流速和泥石流冲击力相似比,以流通区为核心,建造了沟谷泥石流试验模型.试验结果表明,泥石流运动具有显著的阵流特性,阵流间隔时间为10s左右,其间嵌套2~3次弱阵现象;阵流期间,泥石流流速和冲击力均较大;从流通区的源头至沟口,流速呈现非线性增大趋势,且泥石流体中固液两相流速变化趋势相似,弯道处泥石流超高现象显著;泥石流运动初期由于泥石流体中固相和液相混和搅拌不均匀而呈现稀性泥石流特征,随后粘性特性增强.这些现象与现场观测结果基本一致.     

基于震后低压变化的供水管网功能可靠度分析

供水管网的抗震功能是指供水管网在地震作用下能够满足震后城市特定用水需要(需水量和水压)的能力。地震发生后,供水管网一般处于低压供水状态,使得管网中部分用户的水压和水量不能得到全部满足,导致管网部分节点的实际配水量小于需水量。为此,在传统的管网水力分析基础上考虑节点流量随节点水压的动态变化,通过求解非线性水力方程组,得到管网节点实际流量和水压;同时,借鉴结构可靠度分析方法,引入供水管网系统随机水力模型,给出了震后供水管网功能可靠度分析的一次二阶矩方法。以一实际管网为例,演示了震后低压供水时管网功能可靠度分析的应用方法。     

Study of the comparative dynamics of the incorporation of tissue free-water tritium (TFWT) in bulrushes (Typha latifolia) and carp (Cyprinus carpio) in the Almaraz nuclear power plant cooling reservoir

The Almaraz nuclear power plant (Spain) uses the water of Arrocampo reservoir for cooling, and consequently raises the radioactive levels of the aquatic ecosystem of this reservoir. From July 2002 to June 2005, monthly samples of surface water, bulrushes (Typha latifolia) and carp (Cyprinus carpio) were collected from this reservoir. They were analyzed to determine the temporal evolution of the levels of ³H in surface water and of its transfer from the surface water to free-water in the tissues (TFWT) of the aforementioned two organisms. The tritium levels in the surface water oscillate with a biannual period, with their values in the study period ranging between 53 and 433 Bq/L. The incorporation of tritium to bulrushes and carp was fairly similar, the respective mean concentration factors being 0.74 and 0.8 (unitless, as Bq/L tissue water per Bq/L reservoir water). The temporal evolution of the levels fairly closely followed that observed for the surface water tritium, although detailed analysis showed the dominant periodicity for the bulrushes to be annual. This difference reflects the influence on the incorporation of tritium to bulrushes of diverse environmental and metabolic factors, especially evapotranspiration and the seasonal growth of this plant.     

Deposition rates of unattached and attached radon progeny in room with turbulent airflow and ventilation

In this paper deposition rate coefficients for unattached and attached radon progeny were estimated according to a particle deposition model for turbulent indoor airflow described by Zhao and Wu [2006. Modeling particle deposition from fully developed turbulent flow in ventilation duct. Atmos. Environ. 40, 457–466]. The parameter which characterizes turbulent indoor airflow in this model is friction velocity, u*. Indoor ventilation changes indoor airflow and friction velocity and influences deposition rate coefficients. Correlation between deposition and ventilation rate coefficients in the room was determined. It was shown that deposition rate coefficient increases with ventilation rate coefficient and that these parameters of the Jacobi room model cannot be assumed to be independent. The values of deposition rate coefficients were presented as functions of friction velocity and ventilation rate coefficient. If ventilation rate coefficient varies from 0.1 up to 1 h⁻¹, deposition rate coefficients for unattached and attached fractions were estimated to be in the range 3–110 h⁻¹ and 0.015–0.35 h⁻¹, respectively.     

基于面板数据的土地投入对经济增长的影响-以浙江省为例

采用生产函数与面板数据回归模型相结合的研究手段,以地处经济发达地区的浙江省为实证研究区域对土地要素投入对经济增长的影响进行了定量的研究。研究结果表明：(1)就规模效应而言,浙江省的经济增长处于规模报酬不变的发展阶段;(2)浙江省经济增长对劳动力要素的投入最为敏感,其中土地要素、劳动力要素和资本要素增加1个单位的投入量对经济增长的推动为 0.247 3、0.538 5 和 0.321 6;（3）固定资产投入在研究期间是浙江省经济增长的主要推动力,其贡献率达到6823%,而劳动力要素与土地要素则分别为2346%和625%;(4)浙江省土地利用不够集约,在研究期间土地要素对经济增长的影响能被资本要素与劳动力要素有效替代,而劳动力要素则难以被资本投入与土地投入有效替代,劳动集约型产业应该成为浙江省未来发展方向之一。     

CO_2 Emission Induced by Urban Household Consumption in China

Household consumption is one of the important factors that induce COL emission. Based on input-output model, this article calculated the intensity of CO2 emission of different income groups and seven provinces in China, and then estimated total CO2 emission induced by urban household consumption from 1995 to 2004 in China based on statistic data of household living expenditure. The results show that CO2 emission per capita induced by household consumption had increased from 1583 to 2498 kg CO2 during 1995-2004. The ratio of consumption-induced CO2 emission to total CO2 emission had risen from 19% to 30% in the past decade. Indirect CO2 emission accounted for an important part of the consumption-induced emission, the ratio of indirect emission to consumption-induced emission had risen from 69% to 79% during the same period. A significant difference in consumption-induced CO2 emission across different income groups and different regions has been observed. COs emission per capita of higher income groups and developed regions increased faster than that of lower income groups and developing regions. Changing lifestyle has driven significant increase in CO2 emission. Especially, increases in private transport expenditure （for example, vehicle expenditure） and house building expenditure are key driving factors of growth in consumption-induced COL emission. There are big differences in the amount of CO2 emission induced by change in lifestyle across different income groups and provinces. It can be expected that lower income households and developing regions will increase consumption to improve their livings with income growth in the future, which may induce much more CO2 emission. A reasonable level of CO2 emission is necessary to satisfy human needs and to improve living standard, but a noticeable fact is that CO2 emission per capita induced by household consumption in developed areas of China had reached a quite high level. Adjustment in lifestyle towards a low-carbon society is in urgent need.     

The Sustainable Development of ICTs in China： An Empirical Study of Small and Medium-Sized Enterprises

The wide application of new information and communication technologies （ICTs） has been argued to be critical to business success of small and medium-sized enterprises （SMEs）, especially to those in the developing countries. Drawing upon existing literature, this article will examine the determinants of ICTs application in SMEs in China based on data collected from interviews with top managers and/or owners of 70 SMEs. We identify 20 factors affecting ICTs application in SMEs in China and divide them into four broad categories, namely pressures, firm specific factors, technical factors and local milieu. We also pay special attention to the Chinese business environment affecting ICTs application. Our analysis shows that local ICT infrastructure, external pressures from competitors and ICT knowledge of employees are the determinants of Internet application by SMEs, while product characteristics and market target are important factors of e-commerce adoption.