Laboratory Studies of the Hydrogen Kinetic Isotope Effects (KIES) of the Reaction of Non-Methane Hydrocarbons with the OH Radical in the Gas Phase     

R. Iannone  R. S. Anderson  A. Vogel  J. Rudolph  P. Eby  M. J. Whiticar 《Journal of Atmospheric Chemistry》2004,47(2):191-208

The hydrogen kinetic isotope effects (KIEs) of the reactions of 15 non-methane hydrocarbons (NMHCs) with the OH radical were measured at 298 ± 2 K. The measurements were made using NMHCs without artificial isotopic labeling or enrichment. The following average hydrogen KIE values, in per mil (), were obtained: 29.8 ± 2.1 (toluene),51.6 ± 2.1 (n-butane), 97.3± 12.5 (i-butane), 63.2 ± 5.9 (cyclopentane), 10.5 (p-xylene), 26.8 ± 3.5 (ethylbenzene), 65.9± 7.0 (n-pentane), 79.5 ± 9.6 (cyclohexane), 52.8 ± 5.0(n-hexane), 38.9 ± 7.8 (n-heptane), 33.4 ± 3.1 (n-octane), 29.6 ± 1.6(n-nonane), and 29.0 ± 5.3 (n-decane). The KIEs for reactions of two alkenes (cyclohexene and 1-heptene) could not be determined accurately due to interference from reaction with ozone, but nevertheless the results clearly show that the KIEs for reaction of alkenes with OH are significantly lower than those for saturated hydrocarbons. The KIEs for reaction of alkanes are smaller than isotope effects reported in literature for the reactions of NMHCs artificially labeled with deuterium. The main reason for this difference is the reduced probability for reaction at a labeled site for compounds with close to natural deuterium abundance, although some impact of secondary isotope effects cannot be ruled out. Still, the KIEs for NMHCs with natural or close to natural abundance of deuterium are of sufficient magnitude to allow determination of the extent of chemical processing of hydrocarbons in the atmosphere using methods analogous to stable carbon KIE studies. Furthermore, it is shown that combining stable hydrogen and stable carbon isotope ratio data has the potential to also provide valuable information regarding the stable isotope ratios of emissions, and specifically to test one of the key assumptions of the stable isotope hydrocarbon clock, the absence of significant variations of the stable isotope ratio for the emitted NMHCs.  相似文献   

Capture zone,travel time,and solute-transport predictions using inverse modeling and different geological models   总被引：2，自引：1，他引：1  

William?G.?HarrarEmail author  Torben?Obel?Sonnenborg  Hans?J?rgen?Henriksen 《Hydrogeology Journal》2003,11(5):536-548

Six regional-scale flow models are compared to gain insight into how different representations of hydraulic-conductivity distributions affect model calibration and predictions. Deterministic geological models were used to define hydraulic-conductivity distributions in two steady-state flow models that were calibrated to heads and baseflow estimates using inverse techniques. Optimized hydraulic-conductivity estimates from the two models were used to calculate layer and model mean hydraulic-conductivity values. Despite differences in the two geological models, inverse calibration produced mean hydraulic-conductivity values for the entire model domain that are quite similar. The layer and model mean hydraulic-conductivity values were used to generate four additional flow models and forward runs were performed. All of the models adequately simulate the observed heads and total baseflow. The six flow models were used to predict the steady-state impact of a proposed well field, and the flow solutions were used in simulating particle tracking and solute transport. Results of the predictive simulations show that, for this example, simple models of heterogeneity produce capture zones similar to more complex models, but with very different travel times and breakthroughs. Inverse modeling combined with different geological models can provide a measure of capture zone and breakthrough reliability.

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Resumen Se compara seis modelos de flujo a escala regional para conocer cómo afecta a la calibración y a la predicción del modelo diversas representaciones de la distribución de la conductividad hidráulica. Se ha utilizado modelos geológicos deterministas para definir las distribuciones de la conductividad hidráulica en dos modelos de flujo permanente, calibrados mediante técnicas inversas con niveles piezométricos y estimaciones del flujo de base. Se ha adoptado estimaciones optimizadas de la conductividad hidráulica de los dos modelos para calcular las cotas de las capas y sus conductividades hidráulicas medias. A pesar de las diferencias entre ambos modelos geológicos, con la calibración inversa se obtiene valores similares de conductividad hidráulica en todo el dominio. Estos valores de las capas y de las conductividades hidráulicas medias han servido para generar cuatro modelos adicionales de flujo y realizar predicciones. Todos los modelos simulan de forma adecuada los niveles observados y los caudales de base. Los seis modelos han sido aplicados a la predicción del impacto estacionario de un campo de pozos, y las soluciones del flujo permiten simular el transporte de partículas y de solutos. Los resultados de estas predicciones muestran que, para este ejemplo, los modelos sencillos de la heterogeneidad dan lugar a zonas de captura similares a las generadas por modelos más complejos, pero aparecen grandes diferencias en los tiempos de tránsito y en las curvas de llegada. Una combinación de modelación inversa y de modelos geológicos diferentes puede proporcionar una medida de la fiabilidad de la zona de captura y de las curvas de llegada.

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Résumé Six modèles d'écoulement à l'échelle régionale sont comparés afin d'avoir un aperçu de la manière dont les différentes représentations de la distribution de la conductivité hydraulique affectent la calibration et les prédictions de modèles. Des modèles géologiques déterministes ont été utilisés pour définir les distributions de la conductivité hydraulique dans deux modèles d'écoulement en régime permanent qui ont été calibrés avec des estimations des charges et des écoulements de base faites par des techniques inverses. Les estimations optimisées de la conductivité hydraulique de ces deux modèles ont servi à calculer les valeurs de conductivité hydraulique moyenne des couches et du modèle. Malgré des différences entre les deux modèles géologiques, la calibration inverse a donné des valeurs de conductivité hydraulique moyenne pour le domaine complet du modèle qui sont complètement semblables. Les valeurs de la conductivité moyenne des couches et du modèle ont été utilisées pour générer quatre modèles d'écoulement supplémentaires et des traitements ont été effectués. Tous les modèles simulent correctement les charges observées et l'écoulement de base total. Les six modèles ont servi à prédire l'impact en régime permanent d'un champ captant projeté et les solutions d'écoulement ont été utilisées dans une simulation par suivi de particules et de transport de soluté. Les résultats de simulations prédictives montrent que, pour cet exemple, de simples modèles d'hétérogénéité fournissent des zones de capture semblables aux modèles plus complexes, mais pour des temps de parcours et des restitutions très différents. Une modélisation inverse combinée à différents modèles géologiques peut assurer une mesure de la zone de capture et une fiabilité de la restitution.

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关于得尔布干深大断裂北东段延伸去向问题的遥感分析   总被引：2，自引：1，他引：1  

段鹏  方洪宾 《国土资源遥感》2003,14(2):1-4

在1:100万遥感地质解译编图的基础上,经进一步综合解译发现得尔布干深大断裂北东段有可能在阿龙山镇附近演变形成延伸方向和性质均不同的两条分支大断裂.一条呈北东向延伸进入俄罗斯;另一条呈北东东-北东向延伸出境,并以锐角相交形式在阿龙山镇附近与得尔布干深大断裂中南段衔接,构成一醒目斜"Y"型断裂构造展布格局.  相似文献   

利用广西邕宁、灵山地应力资料预报周边地区中强震发震时间的初步探讨   总被引：1，自引：1，他引：0  

吴时平  王锋  陆炳情  谢彩 《华南地震》2003,23(3):1-10

采用回归分析及周期分析法消除了广西邕宁和灵山地应力测值因观测室室温、湿度等因素所引起的年变化;又对地应力资料做了去除长趋势变化和用卡尔曼滤波平滑地应力曲线的处理后,可以看出邕宁、灵山地应力对于200km范围内的Ms4．5—4．7级地震、300km范围内的Ms4．8—5．4级地震以及400km范围内的M5≥5．5级地震具有一定的预报能力。在中强震发生之前的2年内,邕宁、灵山地应力某分向会出现2次以上的超1．5倍均方差异常,且在2次异常所跨越的时段内至少另有1个分向也会显示有1次以上的异常,当第2次异常结束后的8个月内,在上述规定的距离范围内发生中强震的可能性很大。  相似文献   

Effects on the Ionosphere Due to Phenomena Occurring Below it   总被引：4，自引：0，他引：4  

E. Kazimirovsky  M. Herraiz  B. A. De La Morena 《Surveys in Geophysics》2003,24(2):139-184

The terrestrial thermosphere and ionosphere form the most variable part of theEarth's atmosphere. Because our society depends on technological systems thatcan be affected by thermospheric and ionospheric phenomena, understanding,monitoring and ultimately forecasting the changes of the thermosphere–ionosphere system are of crucial importance to communications, navigation and the exploration of near-Earth space. The reason for the extreme variability of the thermosphere–ionosphere system isits rapid response to external forcing from various sources, i.e., thesolar ionizing flux, energetic charged particles and electric fields imposed via the interaction between the solar wind, magnetosphere and ionosphere, as well as coupling from below (meteorological influences) by the upward propagating, broad spectrum,internal atmospheric waves (planetary waves, tides, gravity waves) generated in thestratosphere and troposphere. Thunderstorms, typhoons, hurricanes, tornadoes andeven seismological events may also have observable consequences in the ionosphere.The release of trace gases due to human activity have the potential to cause changes inthe lower and the upper atmosphere.A brief overview is presented concerning the discoveries and experimentalresults that have confirmed that the ionosphere is subject to meteorologicalcontrol (especially for geomagnetic quiet conditions and for middle latitudes).D-region aeronomy, the winter anomaly of radiowave absorption, wave-liketravelling ionospheric disturbances, the non-zonality and regional peculiaritiesof lower thermospheric winds, sporadic-E occurrence and structure, spread-Fevents, the variability of ionospheric electron density profiles and Total ElectronContent, the variability of foF2, etc., should all be considered in connection withtropospheric and stratospheric processes. Ionospheric weather, as a part of spaceweather, (i.e., hour-to-hour and day-to-day variability of the ionospheric parameters)awaits explanation and prediction within the framework of the climatological, seasonal,and solar-cycle variations.  相似文献   

The causes and environmental effects of land use conversion during agricultural restructuring in Northeast China   总被引：1，自引：0，他引：1  

LIU Yansui  GAN Hong  Jay GAO  DENG Xusheng 《地理学报(英文版)》2004,14(4):488-494

1IntroductionLand use change has received lots of attention internationally (Turner etal., 1994). Understanding of the mechanism of land use change and its adverse effect on the environment is conducive to understanding of population, resources, environment and sustainable economic development on the global, national and regional scales. With the rapid rise in human population, human-induced changes in land use form an important component of regional environmental change. In China, to emphasi…  相似文献   

Three-dimensional simulation of ground motion in the Zafarraya Basin (Southern Spain) up to 1.335 Hz under incident plane waves     

F. Luzón  S. A. Gil-Zepeda  F. J. Sánchez-Sesma  C. Ortiz-Alemán 《Geophysical Journal International》2004,156(3):584-594

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Poroelastic shear modulus dependence on pore-fluid properties arising in a model of thin isotropic layers     

James G. Berryman 《Geophysical Journal International》2004,157(1):415-425

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Non‐linear seismic response of the rail‐counterweight system in elevators in buildings     

Mahendra P. Singh  Rildova  Luis E. Suarez 《地震工程与结构动力学》2004,33(2):249-270

Elevators in buildings serve a very important function and are among the critical components of an essential facility. They have several mechanical and electrical components that are known to be susceptible to damage during earthquake occurrences. The counterweights, being the heaviest, are among their most vulnerable components. The ASME code has made several provisions to improve the performance of the counterweights in seismic events. To evaluate their performance under code‐mandated provisions, it is necessary that a comprehensive and realistic analytical model is used. This paper uses a detailed model of a counterweight of a traction elevator to study its in‐plane and out‐of‐plane dynamic behavior. The model incorporates the multiple support inputs and flexibilities of the counterweight guidance system along with their non‐linearities caused by the clearance limitations. The study examines the effect of changing clearances, variability of input motions, and the use of tie brackets on the system response, and evaluates the impact of some of the code provisions on the dynamic behavior of the system. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

华北中北部地区震源参数和场地响应的联合反演   总被引：9，自引：2，他引：9  

王勤彩  高景春  郑斯华  刘杰  陈章立  刁桂苓  赵英萍  刘胜国  张从珍 《中国地震》2004,20(2):187-196

利用遗传算法反演华北中北部地区27个地震震源谱的低频水平、拐角频率和25个台站的场地响应。具体方法是利用研究区的平均衰减模型对记录谱进行路径校正，然后假定每一个地震的ω^2模型，调整低频水平和拐角频率使所有台站场地响应的标准偏差最小，最后给出参与计算的每个台站的场地响应。结果表明，17个基岩台中11个台的场地响应在1～20Hz范围内接近1，6个基岩台的场地响应部分频段放大或缩小3倍以上。8个井下摆台站的场地响应形态相同，表现为低频放大，高频部分迅速衰减。地震矩与震级的关系为logM0=17．1 1．13ML，地震矩与震源半径的关系为logM0=19．4 0．0052r。  相似文献