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991.
Seasonal and Regional Patterns in Performance for a Baltic Sea Drainage Basin Hydrologic Model
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Steve W. Lyon Roya Meidani Ype van der Velde Helen E. Dahlke Dennis P. Swaney Carl‐Magnus Mörth Christoph Humborg 《Journal of the American Water Resources Association》2015,51(2):550-566
This study evaluates the ability of the Catchment SIMulation (CSIM) hydrologic model to describe seasonal and regional variations in river discharge over the entire Baltic Sea drainage basin (BSDB) based on 31 years of monthly simulation from 1970 through 2000. To date, the model has been successfully applied to simulate annual fluxes of water from the catchments draining into the Baltic Sea. Here, we consider spatiotemporal bias in the distribution of monthly modeling errors across the BSDB since it could potentially reduce the fidelity of predictions and negatively affect the design and implementation of land‐management strategies. Within the period considered, the CSIM model accurately reproduced the annual flows across the BSDB; however, it tended to underpredict the proportion of discharge during high‐flow periods (i.e., spring months) and overpredict during the summer low flow periods. While the general overpredictions during summer periods are spread across all the subbasins of the BSDB, the underprediction during spring periods is seen largely in the northern regions. By implementing a genetic algorithm calibration procedure and/or seasonal parameterization of subsurface water flows for a subset of the catchments modeled, we demonstrate that it is possible to improve the model performance albeit at the cost of increased parameterization and potential loss of parsimony. 相似文献
992.
The prediction of the consequences of a runaway reaction in terms of temperature and pressure evolution in a reactor requires the knowledge of the reaction kinetics, thermodynamics and fluid dynamics inside the vessel during venting. Such phenomena and their interaction are complex and yet to be fully understood, especially reactions where the pressure generation is totally or partially due to the production of permanent gases (gassy or hybrid systems). Moreover, these phenomena cannot be easily determined by laboratory scale experiments. In this paper, a dynamic model developed to simulate the behavior of an untempered reacting mixture during venting is presented. The model provides the temperature, pressure and mass inventory profiles before and during venting. A sensitivity study of the model was performed. This modeling work provides some insight regarding the interpretation of the data obtained from untempered system venting experiments. The outcome of this work contribute to improving the design of emergency relief systems for hybrid and gassy systems, where significant progress is still to be made in the experimental and modeling areas. 相似文献
993.
Chemicals used in paint industry are generally comprised of toxic and inflammable substances; they may cause serious problems for humans and environment if safety conditions are neglected. In 2012, rupture of a toluene tank in a paint factory in Iran claimed lives of two workers near the tank. The present study is formulated in order to model the incident. The results showed the area prone to flash fire occurrence and extension. Furthermore, radiation was measured in terms of distance to the tank. A bund wall is also assumed around the vessel in order to determine its influence on evaporation in flash fire area, radiation, and maximum concentration of vapor cloud. The results provided important hints on minimum and required distance of electrical equipment or electrical enclosure (PLC) installation from vessels as well as suitable distance between the vessels. Finally, preventive recommendations were proposed to reduce the risk of potential accidents. 相似文献
994.
995.
本文结合某酒店通风系统噪声治理实例,根据进、排风口空间分布,气流噪声频谱特性等参数,采用Cadna/A软件对噪声源进行了建模,预测了不同楼层进、排风口安装具有不同消声量的消声器后关心点处降噪量。结果表明,酒店通风系统室外进、排风口消声器的消声量可根据各风口噪声对关心点的噪声贡献值大小合理确定消声量,在此基础上根据进、排风口气流噪声频谱等参数设计消声器;只要声学建模合理(特别是声源声功率级等参数取值),借助Cadna/A可较为有效地进行声源识别,确定各进、排风口对各关心点的噪声贡献值大小。 相似文献
996.
Jiankun Xie Dongsheng Wang John van Leeuwen Yanmei Zhao Linan Xing Christopher W. K. Chow 《环境科学学报(英文版)》2012,24(2):276-283
Correlations between raw water characteristics and pH after enhanced coagulation to maximize dissolved organic matter (DOM) removal using four typical coagulants (FeCl3, Al2(SO4)3, polyaluminum chloride (PACl) and high performance polyaluminum chloride (HPAC)) without pH control were investigated. These correlations were analyzed on the basis of the raw water quality and the chemical and physical fractionations of DOM of thirteen Chinese source waters over three seasons. It was found that the final pH after enhanced coagulation for each of the four coagulants was influenced by the content of removable DOM (i.e. hydrophobic and higher apparent molecular weight (AMW) DOM), the alkalinity and the initial pH of raw water. A set of feed-forward semi-empirical models relating the final pH after enhanced coagulation for each of the four coagulants with the raw water characteristics were developed and optimized based on correlation analysis. The established models were preliminarily validated for prediction purposes, and it was found that the deviation between the predicted data and actual data was low. This result demonstrated the potential for the application of these models in practical operation of drinking water treatment plants. 相似文献
997.
Model-based evaluation on the conversion ratio of ammonium to nitrite in a nitritation process for ammonium-rich wastewater treatment 总被引:3,自引:0,他引:3
LI Xiao-ming YANG Qi ZENG Guang-ming A. Cornelius K. H. Rosenwinkel S. Kunst D. Weichgrebe 《环境科学学报(英文版)》2004,16(6):1005-1010
Modeling for nitritation process was discussed and analyzed quantitatively for the factors that influence nitrite accumulation. The results indicated that pH, inorganic carbon source and Hydraulic Retention Time(HRT) as well as biomass concentration are the main factors that influenced the conversion ratio of ammonium to nitrite. A constant high pH can lead to a high nitritation rate and results in high conversion ratio on condition that free ammonia inhibition do not happen. In a CSTR system, without pH control, this conversion ratio can be monitored by pH variation in the reactor. The pH goes down far from the inlet level means a strongly nitrite accumulation. High concentration of alkalinity can promoted the conversion ratio by means of accelerating the nitritation rate through providing sufficient inorganic carbon source(carbon dioxide). When inorganic carbon source was depleted, the nitritation process stopped. HRT adjustment could be an efficient way to make the nitritation system run more flexible, which to some extent can meet the requirements of the fluctuant of inlet parameters such as ammonium concentration, pH, and temperature and so on. Biomass concentration is the key point, especially for a CSTR system in steady state, which was normally circumscribed by the characteristics of bacteria and may also affected by aeration mode and can be increased by prolonging the HRT on the condition of no nitrate accumulation when no recirculation available. The higher the biomass concentration is, the better the nitrite accumulation can be obtained. accumulation 相似文献
998.
Refugia-based conservation offers long-term effectiveness and minimize uncertainty on strategies for climate change adaptation. We used distribution modelling to identify climate change refugia for 617 terrestrial mammals and to quantify the role of protected areas (PAs) in providing refugia across South America. To do so, we compared species potential distribution across different scenarios of climate change, highlighting those regions likely to retain suitable climatic conditions by year 2090, and explored the proportion of refugia inside PAs. Moist tropical forests in high-elevation areas with complex topography concentrated the highest local diversity of species refugia, although regionally important refugia centers occurred elsewhere. Andean–Amazon forests contained climate change refugia for more than half of the continental species’ pool and for up to 87 species locally (17 × 17 km2 grid cell). The highlands of the southern Atlantic Forest also included megadiverse refugia for up to 76 species per cell. Almost half of the species that may find refugia in the Atlantic Forest will do so in a single region—the Serra do Mar and Serra do Espinhaço. Most of the refugia we identified, however, were not in PAs, which may contain <6% of the total area of climate change refugia, leaving 129–237 species with no refugia inside the territorial limits of PAs of any kind. Our results reveal a dismal scenario for the level of refugia protection in some of the most biodiverse regions of the world. Nonetheless, because refugia tend to be in high-elevation, topographically complex, and remote areas, with lower anthropogenic pressure, formally protecting them may require a comparatively modest investment. 相似文献
999.
为向建筑工人提供更具针对性的支持,对比分析精神支持和物质支持的影响效果,分别构建精神支持和物质支持对建筑工人不安全行为的影响机理,基于351名建筑工人调查数据,采用结构方程模型展开实证研究.研究结果表明:精神支持和物质支持对建筑工人安全意识的提高和工作压力的降低都具有显著影响;相较于物质支持,精神支持影响效果更好,更能... 相似文献
1000.
Soni M. Pradhanang Rajith Mukundan Elliot M. Schneiderman Mark S. Zion Aavudai Anandhi Donald C. Pierson Allan Frei Zachary M. Easton Daniel Fuka Tammo S. Steenhuis 《Journal of the American Water Resources Association》2013,49(6):1308-1326
Recent works have indicated that climate change in the northeastern United States is already being observed in the form of shorter winters, higher annual average air temperature, and more frequent extreme heat and precipitation events. These changes could have profound effects on aquatic ecosystems, and the implications of such changes are less understood. The objective of this study was to examine how future changes in precipitation and temperature translate into changes in streamflow using a physically based semidistributed model, and subsequently how changes in streamflow could potentially impact stream ecology. Streamflow parameters were examined in a New York City water supply watershed for changes from model‐simulated baseline conditions to future climate scenarios (2081‐2100) for ecologically relevant factors of streamflow using the Indicators of Hydrologic Alterations tool. Results indicate that earlier snowmelt and reduced snowpack advance the timing and increase the magnitude of discharge in the winter and early spring (November‐March) and greatly decrease monthly streamflow later in the spring in April. Both the rise and fall rates of the hydrograph will increase resulting in increased flashiness and flow reversals primarily due to increased pulses during winter seasons. These shifts in timing of peak flows, changes in seasonal flow regimes, and changes in the magnitudes of low flow can all influence aquatic organisms and have the potential to impact stream ecology. 相似文献