A diffusion approximation for a network of reservoirs with power law release rule     

J. E. Glynn  P. W. Glynn 《Stochastic Environmental Research and Risk Assessment (SERRA)》1996,10(1):17-37

A diffusion approximation for a network of continuous time reservoirs with power law release rules is examined. Under a mild assumption on the inflow processes, we show that for physically reasonable values of the power law constants, the system of processes converges to a multi-dimensional Gaussian diffusion process. We also illustrate how the limiting Gaussian process may be used to compute approximations to the original system of reservoirs. In addition, we study the quality of our approximations by comparing them to results obtained by simulations of the original watershed model. The simulations offer support for the use of the approximation developed here.  相似文献   

Surface NO and NO2 mixing ratios measured between 30° N and 30° S in the Atlantic region     

F. Rohrer  D. Brüning 《Journal of Atmospheric Chemistry》1992,15(3-4):253-267

Surface NO and NO₂ mixing ratios were measured aboard the research vessel Polarstern during the mission ANT VII/1 from 24 September to 5 October 1988. The measurements were taken along the meridian at 30° W in the Atlantic region covering latitudes between 30° N and 30° S. The average mixing ratios were about 12 pptv NO/30 pptv NO₂ in the Northern Hemisphere and about 7 pptv NO/22 pptv NO₂ in the Southern. Elevated mixing ratios of 20 pptv NO/70 pptv NO₂ were found at 12° N (probably due to air masses originating from the surface of West Africa) and in the region of the ITCZ between 8° N and 5° N. Because of probable contamination by the ship, the measured mixing ratios mostly represent upper limits.  相似文献   

Exploring nonlinear characteristics in seismogenic process     

Zhen-Wen An  Lin-Ying Wang  Yao Chen  Han-Meng Pan 《地震学报(英文版)》1993,6(4):923-930

Power spectral characteristics of the seismic activities before and after the seven large earthquake — Haicheng, Tangshan, Lancang, Longling, Mabian, Puer and Songpan are studied by spectrum analysis method. The results show that they all have continuous power spectrum and aperiodic behaviour. When the time away from the large earthquake occurrence, the characteristics of the seismic activities are obviously accompanied by stochastic components. About one year before main shock, the moving orbits constructed by spectrum amplitudes showed the contracting tendency. And the properties during that time may display as flicker noise. One’s another time almost mixed whole phase space. But the essence of seismic activities after main shocks is a chaotic state accompanied with much noises. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 276–281, 1993. This subject is supported by the Chinese Joint Seismological Foundation.  相似文献   

辽宁核电站温坨子厂址东岗断裂活动性研究     

钟以章  张正曙 《中国地震》1993,9(4):364-372

本文在综合地质、地貌、地形变、地震、物探和年代测定等资料的基础上，对东岗断裂的活动性进行了全面分析。所得结果表明，东岗断裂性在中更新世时期有过两期活动，但自晚更新世（１０万年）以来没有活动，故可鉴定为非能动性断裂。  相似文献   

Impacts of droughts on low flows and water quality near power stations     

Gianbattista Bussi  Paul G. Whitehead 《水文科学杂志》2020,65(6):898-913

ABSTRACT

Power plants often use river waters for cooling purposes and can be sensitive to droughts and low flows. Water quality is also a concern, due to algal blooms and sediment loads that might clog filters. We assessed the impacts of droughts on river flow and water quality from the point of view of power plant operation. The INCA (INtegrated CAtchment) water quality model was coupled with a climate model to create a dataset of flow and water quality time series, using the River Trent (UK) as a case study. The result hints to a significant decrease in flows and an increase in phosphorus concentrations, potentially enhancing algal production. Power plants should expect more stress in the future based on the results of this study, due to reduced cooling water availability and decreasing upstream water quality. This issue might have serious consequences also on the whole national power network.  相似文献   

The possible influences of the increasing anthropogenic emissions in India on tropospheric ozone and OH   总被引：2，自引：0，他引：2  

LIU Yu  LI Weiliang  ZHOU Xiuji  I.S.A.ISAKSEN  J.K.SUNDET  HE Jinhai 《大气科学进展》2003,20(6):968-977

A 3-D chemical transport model (OSLO CTM2) is used to investigate the influences of the increasing anthropogenic emission in India. The model is capable of reproducing the observational results of the INDOEX experiment and the measurements in summer over India well. The model results show that when NOx and CO emissions in India are doubled, ozone concentration increases, and global average OH decreases a little. Under the effects of the Indian summer monsoon, NOx and CO in India are efficiently transported into the middle and upper troposphere by the upward current and the convective activities so that the NOx, CO, and ozone in the middle and upper troposphere significantly increase with the increasing NOx and CO emissions. These increases extensively influence a part of Asia, Africa, and Europe, and persist from June to September.  相似文献   

大亚湾扁脑珊瑚中重金属的年际变化及其海洋环境指示意义   总被引：10，自引：0，他引：10       下载免费PDF全文

余克服  陈特固  练健生  王肇鼎  刘东生 《第四纪研究》2002,22(3):230-235

通过对南海北部大亚湾海区1976～1998年扁脑珊瑚Platygyra骨骼Cu,Pb和Cd含量的研究及其与观测记录的比较,初步认为珊瑚可以记录大亚湾海区重金属的年际变化特征;发现1979年和1991年是重金属含量比较高的年份;由扁脑珊瑚记录推测珊瑚中Cd含量短时间内可能受到了核电站兴建的影响,但近20多年来的大亚湾扁脑珊瑚及海水中重金属状况的总体变化过程可能与整个广东海域水质的变化背景基本一致,而与核电站的兴建和运行似乎没有明显的关系  相似文献   

成矿动力系统在混沌边缘的分形生长——一种新的成矿理论与方法论     

於崇文 《矿物岩石地球化学通报》2002,21(2):103-113

笔将复杂性理论及非线性科学与矿床地质学相结合,对我国扬子古陆周缘6个矿集区的基本范式进行系统研究。结果指出,成矿系统总体上是开放、远离平衡、时－空延展的动力学系统。它们具有复杂性和自组织临界性的内禀基本属性,并且在混沌边缘分形生长。  相似文献   

The effects of rock uplift and rock resistance on river morphology in a subduction zone forearc,Oregon, USA     

Sam VanLaningham  Andrew Meigs  Chris Goldfinger 《地球表面变化过程与地形》2006,31(10):1257-1279

Relationships between riverbed morphology, concavity, rock type and rock uplift rate are examined to independently unravel the contribution of along-strike variations in lithology and rates of vertical deformation to the topographic relief of the Oregon coastal mountains. Lithologic control on river profile form is reflected by convexities and knickpoints in a number of longitudinal profiles and by general trends of concavity as a function of lithology. Volcanic and sedimentary rocks are the principal rock types underlying the northern Oregon Coast Ranges (between 46°30′ and 45°N) where mixed bedrock–alluvial channels dominate. Average concavity, θ, is 0·57 in this region. In the alluviated central Oregon Coast Ranges (between 45° and 44°N) values of concavity are, on average, the highest (θ = 0·82). South of 44°N, however, bedrock channels are common and θ = 0·73. Mixed bedrock–alluvial channels characterize rivers in the Klamath Mountains (from 43°N south; θ = 0·64). Rock uplift rates of ≥0·5 mm a⁻¹, mixed bedrock–alluvial channels, and concavities of 0·53–0·70 occur within the northernmost Coast Ranges and Klamath Mountains. For rivers flowing over volcanic rocks θ = 0·53, and θ = 0·72 for reaches crossing sedimentary rocks. Whereas channel type and concavity generally co-vary with lithology along much of the range, rivers between 44·5° and 43°N do not follow these trends. Concavities are generally greater than 0·70, alluvial channels are common, and river profiles lack knickpoints between 44·5° and 44°N, despite the fact that lithology is arguably invariant. Moreover, rock uplift rates in this region vary from low, ≤0·5 mm a⁻¹, to subsidence (<0 mm a⁻¹). These observations are consistent with models of transient river response to a decrease in uplift rate. Conversely, the rivers between 44° and 43°N have similar concavities and flow on the same mapped bedrock unit as the central region, but have bedrock channels and irregular longitudinal profiles, suggesting the river profiles reflect a transient response to an increase in uplift rate. If changes in rock uplift rate explain the differences in river profile form and morphology, it is unlikely that rock uplift and erosion are in steady state in the Oregon coastal mountains. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

大功率电法勘查铝土矿的效果     

袁树森  刘振山  李玉芹  陈晓明 《矿产与地质》2006,20(6):682-685

简要地阐述了河南省西部铝土矿形成的地质背景、矿体特征、地球物理特性;探讨利用大功率电法勘查铝土矿的方法技术;举例说明大功率电法的找矿效果,客观地指出了目前存在的问题,对今后工作提出了自己的看法。  相似文献