蒲石河蓄能电站河岸带近岸砂积地形草本植被分布特征

用样方器采集植物样品的方式在蒲石河蓄能电站河岸带覆砂地带进行植被调查。河岸带植物密度和高度优势种株树与高程相关,相关系数分别为0.687和0.701。蒲石河抽水蓄能电站河岸带按照高程、植被分布规律和距水距离,可以划分为喜水植物茂盛带(距水距离为0~4 m)、混生低草带(距水距离为5~15 m)和非喜水植物茂盛带(距水距离大于15 m)。样方植物株数、植株平均高度、数量优势种株数、单位面积生物量(鲜重)等指标规律分布,是蒲石河蓄能电站植被研究特征指标。土壤覆砂状况对植株高度与种类数量等有影响。     

Analysis of Technology Potential of a Metal-based Latent Heat Storage for Backup Process Steam Supply

An analysis of technology potential of a metal-based high temperature latent heat storage for the application of process steam backup for industrial parks in Germany was carried out. To investigate the integration of the storage into a process steam network, dynamic process simulations were performed. Furthermore, the analysis includes ecological and economical calculations for various fuel types of industrial power plants, plant sizes and auxiliary fuels. Basis of all calculations is an extensive research conducted on the industrial parks in Germany with a dedicated power plant and process steam utilization.     

Application of High Temperature Corrosion-Resistant Materials and Coatings Under Severe Corrosive Environment in Waste-to-Energy Boilers

Corrosion-resistant materials (CRMs) and coatings are key technologies to increase power generation efficiency and reduce maintenance in waste-to-energy (WTE) plants. Corrosion environment became severe as steam temperatures have increased. The steam condition of more than 400 °C/3.9 MPa became possible in WTE boilers by using highly durable corrosion-resistant coatings, such as thermal spray of Al/80Ni20Cr alloy, HVOF-sprayed NiCrSiB alloy, Alloy 625 weld overlay for waterwall tubes and also superheater tubes. Also, the use of 310S type stainless steels and high Cr-high Mo-Ni base and high Si-Cr-Ni-Fe alloys have progressed because of a better understanding of corrosion mechanisms. Furthermore, high durability coatings using cermet and ceramic materials were applied to high temperature superheaters. This paper describes the major developments and the application of CRMs and coating technologies in the last 30 years in WTE plants, the corrosion mechanisms of alloys, the deterioration mechanisms of spray coating layers, and future subjects for the development of corrosion-resistant materials and coatings.     

Analysis of failed nuclear plant components

Argonne National Laboratory has conducted analyses of failed components from nuclear power- gener-ating stations since 1974. The considerations involved in working with and analyzing radioactive compo-nents are reviewed here, and the decontamination of these components is discussed. Analyses of four failed components from nuclear plants are then described to illustrate the kinds of failures seen in serv-ice. The failures discussed are (1) intergranular stress- corrosion cracking of core spray injection piping in a boiling water reactor, (2) failure of canopy seal welds in adapter tube assemblies in the control rod drive head of a pressurized water reactor, (3) thermal fatigue of a recirculation pump shaft in a boiling water reactor, and (4) failure of pump seal wear rings by nickel leaching in a boiling water reactor. Work supported by Commonwealth Edison Company under ACK 85026.     

燃煤火电厂锅炉“四管”的高温腐蚀

燃煤火电厂锅炉的高温腐蚀主要发生在受热面的“四 管”,即水冷壁管、过热器管、再热器管和省煤器管.腐蚀的主要类型是硫腐蚀、氯腐蚀、 水蒸汽腐蚀和钒腐蚀.本文综述了燃煤火电厂锅炉存在的典型高温腐蚀现象和机理,并简要 的介绍了一般防腐蚀措施.     

Predicting Long‐Term Changes in Riparian Bird Communities in Floodplain Landscapes

As anthropogenic impacts on riverine ecosystems expand, both aquatic and terrestrial ecosystems are influenced over large spatiotemporal scales. We predicted how riparian bird communities changed in response to long‐term changes in floodplain landscapes such as woodland expansion (i.e. rapid increases in vegetation cover on gravel bars and the progress of vegetation succession due to a decrease in the frequency and magnitude of flood disturbance). To test the hypothesis that woodland expansion after dam construction reduces the abundance of gravel bar‐nesting birds and increases the abundance of forest‐nesting birds, we estimated historical changes between past and present bird abundances using species distribution models across multiple rivers that were either unregulated or regulated by dams. We created past and present vegetation maps from remote sensing images and used habitat quantities as explanatory variables in the species distribution models. As we hypothesized, the estimated abundance of gravel bar‐nesting birds decreased and that of forest‐nesting birds increased because of woodland expansion in some regulated rivers. This suggests that anthropogenic alterations of riverine conditions (e.g. dam construction) can affect terrestrial ecosystems (e.g. riparian bird communities) through changes in floodplains (e.g. woodland expansion). In addition, our findings highlight the efficacy of combining spatial and temporal analyses when examining long‐term ecological dynamics. Copyright © 2013 John Wiley & Sons, Ltd.     

基于L-系统的分形植物形态建模方法研究

植物生长过程中所表现出来的分形特征是虚拟植物形态发生的重要研究内容,而L-系统在表达具有分形特征的虚拟植物形态上具有明显的不可控特点,严重影响了L-系统的广泛应用。为了更好地研究自然界植物的分形特征,以植物分枝结构和几何形态的量化为前提,建立植物分形特征和L-系统的映射关系,应用改进的L-系统拟合分形植物的生长过程,并结合B-样条曲线动态控制分形植物的弯曲,生成丰富多样的、具有逼真分形效果的虚拟植物形态。     

沉水植物对河道曼宁系数影响的实验研究

该文在实验室水槽中利用三维声学多普勒流速仪(ADV)和波高仪测定水流流速和波浪高度,以此数据研究了河道水生沉水植物对曼宁系数的影响。实验利用人造植物模拟自然植物,研究结果表明沉水植物对水流结构、阻力特性存在显著影响。在分析曼宁系数的变化规律之后提出了新的半经验方程,用以预测不同植物密度、不同波流条件下曼宁系数的变化。曼宁系数主要和植物密度和水流流速有关,同时受波浪的影响。新的方程对曼宁系数的拟合效果良好。     

Spectral‐ALS data fusion for different roughness parameterizations of forested floodplains

Natural river floodplains and adjacent wetlands grow typically a diverse and heterogeneous combination of herbs, shrubs and trees, which play an essential role in determining the total flow resistance. Hydrodynamic effects of trees in forested floodplains can provide the majority of flow resistance during flood events. Nevertheless, ground‐based techniques to acquire vegetation parameters are expensive and difficult to apply over long reaches. This paper presents a novel method of automated roughness parameterization of riparian woody vegetation by fusion of Quickbird multi‐spectral image with airborne laser scanning (ALS) data. The data fusion approach includes: individual tree detection and estimation of vegetation metrics from light detection and ranging (LiDAR) data, assessment of predictive models for the vegetation parameters and spatial mapping of the vegetation parameters for the forest plants in the riparian corridor. The proposed method focuses on estimation of plant density (d), crown diameters (D_C), tree height (h), stem diameter (D_S), crown base height (cbh) and leaf area index (LAI). The procedure is tested along a 14‐km reach of the Sieve River (Tuscany, Italy) characterized by high woody plant density. Due to the complex study area, the data fusion approach explains with variable reliability the local vegetation properties (R²(D_C) = 0.14, R²(h) = 0.84, R²(D_S) = 0.25, R²(cbh) = 0.66). The generated structural parameter maps represent spatially explicit data layers that can be used as inputs to hydrodynamic models used to analyse flow resistance effects in different submergence conditions of vegetation. A simple flow resistance model was applied over a test area comparing the results of the proposed method and a traditional ground‐based approach. The modelling results showed that the new method is able to provide accurate output data to describe the interaction between water levels and bio‐mechanical characteristics of vegetation. The proposed methodology provides a fast, repeatable and accurate way of obtaining floodplain roughness, which enables regular updating of vegetation characteristics. Copyright © 2010 John Wiley & Sons, Ltd.     

机组并网瞬间抢无功现象分析及定值整定策略

发电机组并网瞬间从系统大量抢无功功率,引发本侧母线电压和相邻并网其他机组间无功功率的大幅波动等现象.文中主要从理论和无功功率大幅波动现象进行分析,发现二滩水电站同期装置的电压差、励磁调差系数、机端初始电压等参数的定值整定不合理,从而提出对上述参数的一些整定策略.