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121.
修正SO2被动式采样器的感度 总被引:1,自引:0,他引:1
二氧化硫被动式采样器的采样感度受环境中湿度和硫酸盐等的影响,感度经修正后用于环境监测,其结果与紫外荧光法的相对误差小于10%。 相似文献
122.
感潮河段水环境容量计算方法探讨 总被引:1,自引:1,他引:1
对感潮河段水环境容量的污染物允许排放量的概念进行了分析,提出了基于动态的水质模型并利用计算机仿真和线性规划来进行感潮河段水环境容量计算的基本方法,该文着重介绍计算感潮河段水环境容量的技术方法,通过简化的计算实例对具体过程进行了说明,其原理成立,方法可行。 相似文献
123.
124.
Accidental explosions are a plausible danger to the chemical process industries. In the event of a gas explosion, any obstacles placed within the path of the flame generate turbulence, which accelerates the transient flame and raises explosion overpressure, posing a safety hazard. This paper presents numerical studies using an in-house computational fluid dynamics (CFD) model for lean premixed hydrogen/air flame propagations with an equivalence ratio of 0.7. A laboratory-scale combustion chamber is used with repeated solid obstacles. The transient compressible large eddy simulation (LES) modelling technique combined with a dynamic flame surface density (DFSD) combustion model is used to carry out the numerical simulations in three-dimensional space. The study presented uses eight different baffle configurations with two solid obstructions, which have area blockage ratios of 0.24 and 0.5. The flame speed, maximum rate of pressure-rise as well as peak overpressure magnitude and timing are presented and discussed. Numerical results are validated against available published experimental data. It is concluded that, increasing the solid obstacle area blockage ratio and the number of consecutive baffles results in a raised maximum rate of pressure rise, higher peak explosion overpressure and faster flame propagation. Future model development would require more experimental data, probably in a more congested configuration. 相似文献
125.
动测法检测桩承载力和完整性 总被引:1,自引:0,他引:1
笔者针对京秦客运通道提速改造工程 ,利用低应变动测法对混凝土灌注桩承载力和桩完整性进行了检测 ;根据低应变动测桩的频率理论 ,考虑波在不同介质中的传播特性 ,推导了频率公式 ;从而得出了低应变动测确定单桩承载力的理论依据。对桩检测方法和判定标准进行了分类 ,对桩的承载力和桩身完整性进行了分析讨论。为低应变动测分析法在工程上的应用积累了经验 ,对该法在工程上的推广应用具有指导意义。 相似文献
126.
采用SBR工艺接种成熟的强化生物除磷(EBPR)絮状污泥,研究了不同浓度纳米ZnO(ZnO NPs)对颗粒化EBPR系统性能的影响。结果表明:低浓度(≤1 mg/L)ZnO NPs可促进厌氧释磷和好氧吸磷作用;随着ZnO NPs浓度的增加,磷酸盐及COD去除能力受到明显抑制;在厌氧释磷过程中,PAOs对ZnO NPs的毒性更为敏感;与未受ZnO NPs污染的系统相比,ZnO NPs浓度为15 mg/L条件下的释磷速率与吸磷速率分别下降了0.1 mg/(gVSS·min)和0.15 mg/(gVSS·min)。 相似文献
127.
Most metapopulation models neglect the local dynamics, and systems characterized by slow population turnover, time lags and non-equilibrium, are only rarely examined within a metapopulation context. In this study we used a realistic, spatially explicit, dynamic metapopulation model of a long-lived grassland plant, Succisa pratensis, to examine the relative importance of local population dynamics, and short and long-distance dispersal of seeds. 相似文献
128.
We report the development of a new spatially explicit individual-based Dynamic Global Vegetation Model (SEIB–DGVM), the first DGVM that can simulate the local interactions among individual trees within a spatially explicit virtual forest. In the model, a sample plot is placed at each grid box, and then the growth, competition, and decay of each individual tree within each plot is calculated by considering the environmental conditions for that tree as it relates to the trees that surround it. Based on these parameters only, the model simulated time lags between climate change and vegetation change. This time lags elongated when original biome was forest, because existing trees prevent newly establish trees from receiving enough sunlight and space to quickly replace the original vegetation. This time lags also elongated when horizontal heterogeneity of sunlight distribution was ignored, indicating the potential importance of horizontal heterogeneity for predicting transitional behavior of vegetation under changing climate. On a local scale, the model reproduced climate zone-specific patterns of succession, carbon dynamics, and water flux, although on a global scale, simulations were not always in agreement with observations. Because the SEIB–DGVM was formulated to the scale at which field biologists work, the measurements of relevant parameters and data comparisons are relatively straightforward, and the model should enable more robust modeling of terrestrial ecosystems. 相似文献
129.
闽江流域森林资源与环境的动态分析 总被引:3,自引:0,他引:3
该文对闽江流域的森林与生态环境的变动情况及相互关系进行阐述,并提出了相应的对策建议。 相似文献
130.
一维河流水质模拟研究 总被引:1,自引:0,他引:1
根据对流扩散方程推导一维河流水质动态和稳态模型,在此基础上导出多河段一维河流水质模拟(动态和稳态)矩阵公式.在乌鲁木齐地区水磨河上分别对所建模型进行了检验并对检验结果作了简要讨论。 相似文献