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排序方式: 共有198条查询结果,搜索用时 31 毫秒
191.
Eva Holtanová Jaroslava Kalvová Jiří Mikšovský Petr Pišoft Martin Motl 《Studia Geophysica et Geodaetica》2010,54(3):513-528
In this study we present results of uncertainty analysis in eight regional climate model (RCM) outputs over the area of the
Czech Republic. The RCM simulations come from the EU 5th Framework program project PRUDENCE (Prediction of Regional scenarios
and Uncertainties for Defining EuropeaN Climate change risks and Effects). Using the analysis of variance we have found that
the main source of uncertainty in projected changes of mean seasonal air temperature is the driving global climate model.
In case of precipitation changes, the RCM is the largest source of uncertainty in all seasons except for the spring. With
the second method, the Reliability Averaging method, we have focused on the uncertainty coming from the RCM itself. The results
of both methods showed that the relative contribution of the regional climate model to the uncertainty of simulated mean seasonal
air temperature and precipitation changes is largest in summer and smallest in winter. 相似文献
192.
J. Le Coz M. Michalková A. Hauet M. C̆omaj G. Dramais K. Holubová H. Piégay A. Paquier 《地球表面变化过程与地形》2010,35(3):249-261
The morphological evolution of the entrances and exits of abandoned river channels governs their hydrological connectivity. The study focusses on flow and sediment dynamics in the exit of a cutoff meander where the downstream entrance is still connected to the main channel, but the upstream entrance is closed. Two similar field and laboratory cases were investigated using innovative velocimetry techniques (acoustic Doppler profiling, image analysis). Laboratory experiments were conducted with a mobile‐bed physical model of the Morava River (Slovakia). Field measurements were performed in the exit of the Port‐Galland cutoff meander, Ain River (France). Both cases yielded consistent and complementary results from which a generic scheme for flow patterns and morphological evolution was derived. A simple analogy with flows in rectangular side cavities was used to explain the recirculating flow patterns which developed in the exit. A decelerating inflow deposits bedload in the downstream part of the cavity, while the upstream part is eroded by an accelerating outflow, leading to the retreat of the upstream bank. In the field, strong secondary currents were observed, especially in the inflow, which may enhance the scouring of the downstream corner of the cavity. Also, fine sediment deposits constituted a silt layer in a transitional zone, located between the mouth of the abandoned channel and the oxbow‐lake within the cutoff meander. Attempts at morphological prediction should consider not only the flow and sediment conditions in the cavity, but also the dynamics of the main channel. Copyright © 2010 John Wiley & Sons, Ltd 相似文献
193.
“数字化科学工程”构建中的广义非线性数据处理的一种新算法 总被引:6,自引:3,他引:3
在当今各国正大力倡导的“数字国家”、“数字城市”、“数字矿山”等科学工程构建中的数据处理是基础和核心 ,其数据又具有多源、多维、多类型、多时态、多精度并具有非线性特征等特点 ,其数据处理的参数估计模型大都是复杂的非线性函数模型 ,模型中的参数有非随机参数 ,也有随机参数 ,这些系广义非线性数据处理 ,应采用广义非线性动态最小二乘数据处理的理论、方法来完成。本文提出了一种新的解算模型和解算方法 ,将问题分离 ,转换成单变量的一般非线性最小二乘问题求解。先按非线性拟合模型线性逼近法求得靠近真值的最优初值 ,再按非线性最小二乘解算方法求解参数估值。本方法使原来的高维方程得以简化 ,还不用计算二阶导数 ,大大简化了计算难度 ,并大大减少了迭代次数和计算工作量。 相似文献
194.
This is the first record of a representative of the organic-walled dinoflagellate cyst genus Palynodinium from the New Zealand region. Previously, Palynodinium grallator has been reported from two sites in offshore Tasmania during Ocean Drilling Program, Leg 189. The new species Palynodinium minus is found consistently in latest Maastrichtian? and earliest Danian strata (latest Haumurian–earliest Teurian) in two sections located along the mid-Waipara and Grey rivers, North Canterbury, South Island. It occurs in a narrow stratigraphic interval at the Cretaceous–Paleogene transition and is potentially a stratigraphically important index species in the region. Its range coincides with that of the global earliest Danian index fossil Carpatella cornuta and a basal Danian acme interval of Trithyrodinium evittii, and is correlated to ca. 65.5–65.2 Ma. Its highest occurrence is at the base of an acme interval of Palaeoperidinium pyrophorum. It has only been recorded from sections composed of siliciclastic shelf sediments, suggesting that it might have had a palaeoecological preference for relatively near-shore environments. 相似文献
195.
吉林省煤炭资源主要赋存于侏罗系、白垩系,其次为石炭一二叠系、古近系和新近系,根据煤炭资源赋存特征可划分为七个含煤区带。截至到2007年末,全省保有煤炭资源储量20.4亿t,剩余服务年限不足15年。在19个主要生产矿区中辽源、浑江、舒兰、蛟河以及珲春等勘查程度较高,大多数老矿区外围和主要聚煤区带大部地区处于预查一普查阶段。通过分析提出实现找煤工作新突破的4个方向:①老矿区(矿井)的外围和深部找煤;②推覆构造下和玄武岩盖层下找煤;③松辽盆地西缘和东缘找煤;④东部山区勘查空白区找煤。 相似文献
196.
Jiří Mikšovský Rudolf Brázdil Petr Štĕpánek Pavel Zahradníček Petr Pišoft 《Climatic change》2014,125(2):253-264
Among the key problems associated with the study of climate variability and its evolution are identification of the factors responsible for observed changes and quantification of their effects. Here, correlation and regression analysis are employed to detect the imprints of selected natural forcings (solar and volcanic activity) and anthropogenic influences (amounts of greenhouse gases—GHGs—and atmospheric aerosols), as well as prominent climatic oscillations (Southern Oscillation—SO, North Atlantic Oscillation—NAO, Atlantic Multidecadal Oscillation—AMO) in the Czech annual and monthly temperature and precipitation series for the 1866–2010 period. We show that the long-term evolution of Czech temperature change is dominated by the influence of an increasing concentration of anthropogenic GHGs (explaining most of the observed warming), combined with substantially lower, and generally statistically insignificant, contributions from the sulphate aerosols (mild cooling) and variations in solar activity (mild warming), but with no distinct imprint from major volcanic eruptions. A significant portion of the observed short-term temperature variability can be linked to the influence of NAO. The contributions from SO and AMO are substantially weaker in magnitude. Aside from NAO, no major influence from the explanatory variables was found in the precipitation series. Nonlinear forms of regression were used to test for nonlinear interactions between the predictors and temperature/precipitation; the nonlinearities disclosed were, however, very weak, or not detectable at all. In addition to the outcomes of the attribution analysis for the Czech series, results for European and global land temperatures are also shown and discussed. 相似文献
197.
介绍了2013~2014年使用A10/028和FG5/214两台绝对重力仪在国家现代测绘基准体系基础设施建设一期工程中绝对重力观测的情况,并对观测结果进行分析。结果显示,两台绝对重力仪观测结果精度及较差都在5 μGal以内,满足高精度重力基准建设的技术要求;A10/028具有一定的野外观测适应性,FG5/214对重力细微变化信号的捕获具有优势,两台绝对重力仪同期观测对于提高观测结果的可靠性和准确度具有积极的作用。 相似文献
198.