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11.
Alex Potapov Jim R. Muirhead Subhash R. Lele Mark A. Lewis 《Ecological modelling》2011,222(4):964-972
Freshwater aquatic systems in North America are being invaded by many different species, ranging from fish, mollusks, cladocerans to various bacteria and viruses. These invasions have serious ecological and economic impacts. Human activities such as recreational boating are an important pathway for dispersal. Gravity models are used to quantify the dispersal effect of human activity. Gravity models currently used in ecology are deterministic. This paper proposes the use of stochastic gravity models in ecology, which provides new capabilities both in model building and in potential model applications. These models allow us to use standard statistical inference tools such as maximum likelihood estimation and model selection based on information criteria. To facilitate prediction, we use only those covariates that are easily available from common data sources and can be forecasted in future. This is important for forecasting the spread of invasive species in geographical and temporal domain. The proposed model is portable, that is it can be used for estimating relative boater traffic and hence relative propagule pressure for the lakes not covered by current boater surveys. This makes our results broadly applicable to various invasion prediction and management models. 相似文献
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T. D. Streltsova Abdel-Aziz I. Kashef 《Journal of the American Water Resources Association》1974,10(5):995-1008
ABSTRACT: An approach, based on the realization of the vertical components of flow is presented to determine the free surface of gravity wells and the shape of salt-water upconing in artesian aquifers. The transitional stages from pumping fresh water to pumping salt water at the critical condition are discussed. Vertical hydraulic resistances, being determined and included in the flow domain, allow the use of the finite-difference approximation in a simple form. The suggested approach implies the use of either simple modeling or computing techniques. 相似文献
13.
Jean Vernin Hervé Trinquet George Jumper Edmund Murphy Anthony Ratkowski 《Environmental Fluid Mechanics》2007,7(5):371-382
Herein we present a campaign dedicated to the detection and the characterization of Gravity Waves (GW) in the Earth’s atmosphere
in relation to the generation of Optical Turbulence (OT). The observations took place in France from 17 to 24 July 2002 at
the Haute Provence Observatory (OHP) and simultaneously at the Sirene Observatory, some 20 km apart. From both sites, several
balloons were launched that measured the classical PTU-Wind profiles and additionally the structure constant of the temperature
field vertical profiles. A Generalized Scidar (GS) technique was implemented at the 1.93 m-diameter OHP telescope, providing profiles every minute. From our observations, a significant amount of GW activity was observed at both sites, but without
clear evidence of correlation between the two sites. It seems from our observations that a wide spectrum of GW is present
at a given altitude and that this could result in a lack of correlation between observations made from two sites 20 km apart.
Most GW are non-stationary with long horizontal wavelengths (λ ∼ 100–200 km), kilometric vertical wavelengths (λ ~ 0.5–2 km)
and long intrinsic period (T ~ 2–15 h). They belong in the category of “hydrostatic rotating or non-rotating waves”. Layers of optical turbulence detected
by balloons and the Scidar technique correlate well with regions of GW activity.
The U.S. Government’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged. 相似文献
14.
Fishing capacity management policies have been traditionally implemented at national level with national targets for capacity reduction. More recently, capacity management policies have increasingly targeted specific fisheries. French fisheries spatially vary along the French coastline and are associated to specific regions. Capacity management policies, however, ignore the capital mobility associated with second-hand vessel trade between regions. This is not an issue for national policies but could limit the effectiveness of regional capacity management policies. A gravity model and a random-effect Poisson regression model are used to analyze the determinants and spatial extent of the second-hand market in France. This study is based on panel data from the French Atlantic Ocean between 1992 and 2009. The trade flows between trading partners is found to increase with their sizes and to be spatially concentrated. Despite the low trade flows between regions, a net impact analysis shows that fishing capacity is redistributed by the second-hand market to regions on the Channel and Aquitaine from central regions. National capacity management policies (constructions/destructions) have induced a net decrease in regional fleet capacity with varying magnitude across regions. Unless there is a change of policy instruments or their scale of implementation, the operation of the second-hand market decreases the effectiveness of regional capacity management policies in regions on the Channel and Aquitaine. 相似文献
15.
本文旨在介绍一种简单易行的重磁相关分析方法及其在解析地质构造问题时的作用,该方法在湖南华容地区的应用收到了较好的效果。 相似文献
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17.
餐饮业油烟气排放量的重量法监测 总被引:12,自引:0,他引:12
通过试验提出了一种监测餐饮业油烟气的方法,方法首次以单位体积油烟气中总有机物的质量来表示油烟气在空气中的浓度。通过试验选择了最佳监测条件;以石油醚作吸收剂,用KB-6A型或TMP-1500型空气采样器,控制流量在0.4L/min,采集油烟气,并在40℃时挥发掉吸收剂,经称量得到监测结果,该法所需仪器和试剂简单,并在实际监测中得到了预期的结果。 相似文献
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Nan Zhao Huu Hao Ngo Yuyou Li Xiaochang Wang Lei Yang Pengkang Jin Guangxi Sun 《Frontiers of Environmental Science & Engineering》2019,13(4):62
20.
采用零排放新工艺处理蚀刻废液 总被引:1,自引:0,他引:1
广州市某化工厂开发出一套对线路板蚀刻废液进行大规模集中资源化处理的零排放处理新工艺,该工艺通过在固相条件下生成氧化铜并用重力分选的方法将其分离出来,克服了原有工艺的缺陷,使废液中所有的成分能够在较低的处理成本下全部分离回收,无三废排出,达到了清洁生产的要求.对其工艺条件进行深入研究,通过正交试验优化了工艺条件. 相似文献