footprint方法在湍流扩散分析中的应用     

夏兰  陈辉  卞林根 《气候与环境研究》2010,15(3):269-278

引入通量footprint分析方法,结合广西白龙核电厂拟建厂址的湍流实测资料,分析了观测站点不同方向上的通量footprint,并由此确定了水平扩散尺度及水平扩散时间,最终估算了水平扩散参数。与环境评价导则中推荐的扩散时间计算所得的水平扩散参数进行了对比分析。结果表明,离岸流的扩散参数比向岸流大,有利于湍流扩散,从而证明扩散参数具有偏保守性和局地扩散的特性。分析表明,footprint方法在湍流扩散参数分析中具有实际的应用价值。  相似文献   

Frequency spectrum of toroidal Alfvén mode in a neutron star with Ferraro’s form of nonhomogeneous poloidal magnetic field     

S. I. Bastrukov  H.-K. Chang  I. V. Molodtsova  E.-H. Wu  G.-T. Chen  S.-H. Lan 《Astrophysics and Space Science》2009,323(3):235-242

Using the energy variational method of magneto-solid-mechanical theory of a perfectly conducting elastic medium threaded by magnetic field, the frequency spectrum of Lorentz-force-driven global torsional nodeless vibrations of a neutron star with Ferraro’s form of axisymmetric poloidal nonhomogeneous internal and dipole-like external magnetic field is obtained and compared with that for this toroidal Alfvén mode in a neutron star with homogeneous internal and dipolar external magnetic field. The relevance of considered asteroseismic models to quasi-periodic oscillations of the X-ray flux during the ultra powerful outbursts of SGR 1806−20 and SGR 1900+14 is discussed.  相似文献   

Near-IR age-dating of red supergiant-dominated stellar populations     

Ariane Lançon  Jay S. Gallagher  Moustapha Mouhcine  Linda J. Smith  Djazia Ladjal  Richard de Grijs 《Astrophysics and Space Science》2009,324(2-4):241-245

We present new spectral synthesis models for solar metallicity stellar populations, based on a library of stellar spectra that extends across near-IR wavelengths out to 2.4 µm at a resolution approaching 1000. We show that the spectra of massive star clusters in the starburst galaxy M 82 can be reproduced very well with these models. We compare near-IR spectroscopic ages with optical ages, and discuss the main sources of (systematic) errors that still affect those ages.  相似文献   

The mass-to-light ratio of rich star clusters     

Christian M. Boily  Jean-Julien Fleck  Ariane Lançon  Florent Renaud 《Astrophysics and Space Science》2009,324(2-4):265-269

We point out a strong time evolution of the mass-to-light conversion factor, η, commonly used to estimate masses of unresolved star clusters from observed cluster spectrophotometric measures. We present a series of gas-dynamical models, coupled with the Cambridge stellar evolution tracks, to compute line-of-sight velocity dispersions and half-light radii weighted by the luminosity. We explore a range of initial conditions, varying in turn the cluster mass and/or density, and the stellar population’s initial mass function. We find that η, and hence the estimated cluster mass, may increase by as much as a factor of three over time-scales of 50 million yr. We apply these results to an hypothetic cluster mass distribution function (d.f.), and show that the d.f. shape may be strongly affected at the low-mass end by this effect. Fitting truncated isothermal (Michie–King) models to the projected light profile leads to over-estimates of the concentration parameter, c, of δ c≈0.3 compared to the same functional fit applied to the projected mass density.  相似文献   

容许土壤流失量的研究现状及其设想   总被引：4，自引：0，他引：4  

李兰  周忠浩  刘刚才 《地球科学进展》2005,20(10):1127-1134

成土速率、土地生产力和沟蚀的控制程度是容许土壤流失量（[WTBX]T值）制定中必不可少的因素。国际上现有的T值标准主要是从土层厚度和成土速率出发,并结合实际应用的可能而定。详述了T[WTBZ]值的研究历史其主要影响因素,介绍了利用Barth模型和基于风险评价理论的[WTBX]T值的估算方法,对现有T值研究方法和研究结果中存在的问题进行了分析,提出了T[WTBZ]值应该从土壤形成速率特性（自然属性）、合理的生产力水平持续性（社会属性）、水土环境的长久安全性（自然和社会属性）几方面属性进行相应的研究。  相似文献   

河南省自然灾害监测与评估信息系统研究   总被引：3，自引：0，他引：3  

武洪涛  张震宇  邬恺夫  马兰  常宗广 《地域研究与开发》2005,24(6):125-128

文章介绍了河南省自然灾害监测与评估信息系统的系统目标、整体设计和数据库的建立,整个系统由重大灾害监测预警、黄河下游洪水预报、淮河上游洪灾监测评估、快速反应、防灾减灾决策等子系统组成,子系统通过一定的数据接口,集成为一体化的系统,实现无准备地区突发性重大灾害的监测和应急评估,并及时为政府提供完整的减灾预案和灾害应急预案。  相似文献   

华北平原降水的长期趋势分析(英文)   总被引：4，自引：1，他引：3  

范兰  吕昌河  杨彪  陈朝 《地理学报(英文版)》2012,22(6):989-1001

The North China Plain (NCP) is the most important food grain producing area in China and has suffered from serious water shortages. To capture variation water availability, it is necessary to have an analysis of changing trends in precipitation. This study, based on daily precipitation data from 47 representative stations in NCP records passed the homogeneity test, analyzed the trend and amplitude of variation in monthly, seasonal and annual precipitation, annual maximum continuous no-rain days, annual rain days, rainfall intensity, and rainfall extremes from 1960 to 2007, using the MannKendall (M-K) test and Sen’s slope estimator. It was found that monthly precipitation in winter had a significant increasing trend in most parts, while monthly precipitation in July to September showed a decreasing trend in some parts of NCP. No significant changing trend was found for the annual, dry and wet season precipitation and rainfall extremes in the majority of NCP.A significant decreasing trend was detected for the maximum no-rain duration and annual rain days in the major part of NCP. It was concluded that the changing trend of precipitation in NCP had an apparent seasonal and regional pattern, i.e., precipitation showed an obvious increasing trend in winter, but a decreasing trend in the rainy season (July to September), and the changing trend was more apparent in the northern part than in the southern and middle parts. This implies that with global warming, seasonal variation of precipitation in NCP tends to decline with an increasing of precipitation in winter season, and a decreasing in rainy season, particularly in the sub-humid northern part.  相似文献   

广域网加速在FY-3气象卫星数据传输中的应用          下载免费PDF全文

卫兰  林曼筠  赵现纲  张战云 《应用气象学报》2012,23(1):121-128

风云三号 (FY-3) 极轨气象卫星数据传输系统需通过广域网链路,将海量卫星观测数据从卫星接收站快速传送到资料处理中心。该文研究广域网加速技术,解决广域网链路中传输气象卫星海量观测数据延迟高、带宽利用低等难题。文中针对FY-3气象卫星观测数据传输量大、时效要求高的特点,分别分析了数据压缩、数据缓存和协议优化3种不同加速技术对卫星数据的传输优化效果,并根据分析结果提出了一种适用于气象卫星数据的广域网传输加速架构。该架构结合3种不同加速技术设计了TCP代理模块、数据段索引模块和HS-TCP传输模块以及相应算法分别实现了数据压缩与缓存和协议优化等功能。通过测试和实际运行表明:在该加速架构下卫星数据广域网传输速率提高了50%~243%。  相似文献   

西湖凹陷平西地区古沟谷内隐蔽油气藏潜力     

张兰  何贤科  段冬平  程俊阳  陈晨  汪文基 《海洋地质前沿》2022,38(1):41-50

西湖凹陷平湖油气田经多年的勘探开发,取得了丰硕的成果,但也面临着后备储量不足的严峻现状.油气田西部的平西地区,占地面积大、研究程度低,是发现新增资源量的潜在地区.利用三维地震资料,从古地貌着手,在平西地区自南向北识别出多个古沟谷,其限制型地貌为隐蔽油气藏提供了有利背景.结合古生物、微量元素、测录井、岩芯、地震等资料综合...  相似文献   

太湖流域洪水的周期信息图及其可公度性法预测   总被引：2，自引：0，他引：2  

胡昌新  胡岚 《水文》2009,29(5)

据1991年江淮地区异常洪水预测的启示,从太湖流域的历史旱涝记载文献,环湖洪水调查成果和实测水位雨量记录等资料,进行太湖流域洪水周期规律的探讨.通过多种周期提取方法,建立起洪水周期信息图,发现太湖洪水存在着8～11年、20～24年、37～42年和58～62年的周期现象,然后采用可公度性法预测,以供防洪减灾参考.  相似文献