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761.
762.
This work aims to determine the maximum concentration and downwind distance at the earth's surface in two methods Briggs and standard for two conditions are slightly unstable and neutral by using the Gaussian equation at different effective heights and wind seeped at (8.9, 8.5 and 8 m/s) under lateral and vertical dispersion coefficient measurement. 相似文献
763.
Streamflow Depletion Modeling: Methods for an Adaptable and Conjunctive Water Management Decision Support Tool 下载免费PDF全文
Xander Huggins Tom Gleeson Hailey Eckstrand Ben Kerr 《Journal of the American Water Resources Association》2018,54(5):1024-1038
Groundwater pumping depletes streamflow, which can have significant ecological impacts depending on the magnitude of depletion relative to environmental flow needs. Streamflow depletion estimates from groundwater pumping have been quantified using both analytical and numerical methods, but are not routinely compared to environmental flow needs or used in practical water management tools. Decision support tools that incorporate groundwater dynamics are becoming increasingly necessary for water managers as groundwater regulations become more important in environmental policy, particularly concerning the preservation of environmental flow needs. We develop and apply methods for a web‐based decision support tool for conjunctive groundwater and surface water management, demonstrated using a case study watershed in British Columbia, Canada. Open‐source data are analyzed with a combination of spatial algorithms and previously developed analytical models, such that the tool can be applied to other regions. Streamflow depletion estimates are calculated in four regions in the largely undeveloped Bulkley Valley, British Columbia. Our transparent methodology has geographic and data input flexibility which is a significant improvement on currently existing water management tool methods. 相似文献
764.
通过分析事件驱动原理,将事件驱动机制(EDI)融入虚拟现实地理信息系统(VRGIS)的建模框架,探索基于VRGIS的事件驱动时空模型及其在城市环境污染突发事件响应中的应用前景以及主要技术设计过程,旨在为资源与环境的可持续利用研究提供一个形象直观的虚拟演示平台来反映城市中环境变化的空间响应及其对策定制等问题。 相似文献
765.
饮用水中可溶性氟化物是公众摄入氟的主要途径,其含量水平影响人体健康.分别于2015~2017年的丰水期和枯水期6次随机采集监测了嘉陵江下游52个饮用水样中氟化物含量,并基于地理信息系统平台和健康风险指数法进行了评价.结果表明,该区域饮用水中氟化物浓度平均为0.20~0.25 mg/L.除2015年部分样点外,其余样点的... 相似文献
766.
以平遥古城为例,探究游客信息行为对文化遗产旅游难忘体验的作用路径和异质性的调节效果。结果发现:游客信息行为对文化遗产旅游难忘体验的影响有直接影响和间接影响两条路径;异质性游客在信息对难忘体验的影响上存在显著调节效果;遗产地吸引力通过对游客再访意图的影响完全转化为难忘体验来发挥作用。 相似文献
767.
Satoru Isoda 《环境科学学报(英文版)》2013,(S1):S172-S179
Power conversion efficiency of p-i-n type microcrystalline silicon (c-Si:H) solar cells has been analyzed in terms of sequential processes of photo-induced electron transfer. The effect of the excitonic state on the charged carrier generation has been studied compared to a conventional scheme in which only charged carriers are taken into account for the operation of the solar cells. A numerical model has been developed to calculate current-voltage characteristics of solar cells on the basis of two types of charged carrier generation processes (exciton process and charged carrier process). The light trapping effect due to a textured back surface reflector (BSR) was embedded in the numerical model by using the effective medium theory in combination with the matrix method in the field of the electromagnetic theory of light. As an application of this modeling, it was found that the reported data of the power conversion efficiency were not explained by the conventional charged carrier process model and that the combined model of the charged carrier process with the exciton process well explains the performance of the p-i-n type c-Si:H solar cells. In this way, the typical power conversion efficiencies were estimated to be 10.5% for the device (i-layer thickness: 1.8 m) with the BSR (period: 600 nm; height: 250 nm) and 8.6% for the device with the flat reflector under the condition that the fractions of the exciton process and charged carrier process were 60% and 40%, respectively. 相似文献
768.
Power conversion efficiency of p-i-n type macrocrystalline silicon (µc-Si:H) solar cells has been analyzed in terms of sequential processes of photo-induced electron transfer. The effect of the excitonic state on the charged carrier generation has been studied compared to a conventional scheme in which only charged carriers are taken into account for the operation of the solar cells. A numerical model has been developed to calculate current-voltage characteristics of solar cells on the basis of two types of charged carrier generation processes (exciton process and charged carrier process). The light trapping effect due to a textured back surface reflector (BSR) was embedded in the numerical model by using the effective medium theory in combination with the matrix method in the field of the electromagnetic theory of light. As an application of this modeling, it was found that the reported data of the power conversion efficiency were not explained by the conventional charged carrier process model and that the combined model of the charged carrier process with the exciton process well explains the performance of the p-i-n type μc-Si:H solar cells. In this way, the typical power conversion efficiencies were estimated to be 10.5% for the device (i-layer thickness: 1.8 μm) with the BSR (period: 600 nm; height: 250 nm) and 8.6% for the device with the flat reflector under the condition that the fractions of the exciton process and charged carrier process were 60% and 40%, respectively. 相似文献
769.
770.
In planning a product life cycle inventory analysis, the correct choice of methodology often depends on market information. This paper discusses a number of points in the life cycle inventory methodology (choice of product alternatives, geographical system boundaries, technological levels and co-product allocation rules) where the market aspect becomes obvious and where a disregard for these aspects may lead to serious flaws in the results. 相似文献