Approximate Solutions For The Obukhov Length And The Surface Fluxes In Terms Of Bulk Richardson Numbers     

H. A. R. De Bruin  R. J. Ronda  B. J. H. Van De Wiel 《Boundary-Layer Meteorology》2000,95(1):145-157

Simple analytic approximate solutions arepresented for the set of equations that follows fromthe Monin–Obukhov flux-profile relationships using thestability functions of Dyer (unstable case) andBeljaars–Holtslag (stable case). Several publicationsare devoted to the same subject, however the currentapproach contains some new features, namely: (a) itappears to be more accurate for unstable situationsand (b) it applies also to the general case where windspeed (u) and potential temperature() are given at different levels. In order toillustrate the accuracy of the approach a comparisonwith the actual solutions is presented for someselected combinations of and u levelstypical for various practical applications.  相似文献   

二安替比林对羟基苯乙烯基甲烷与钒的高灵敏显色反应   总被引：1，自引：1，他引：0  

周世萍  段德良  杨光宇  尹家元  杨文凡 《岩矿测试》2000,19(2):116-118

合成了试剂二安替比林对羟基苯乙烯基甲烷 (DApHVM) ,研究了它与V(Ⅴ )的显色反应。在H3PO4介质中 ,Mn(Ⅱ )和Tween 2 0协同作用下 ,DApHVM与V(Ⅴ )生成红色产物 ,λmax为 540nm ,ε=1 0 3× 1 0 6 L·mol-1 ·cm-1 ,V(Ⅴ )的质量浓度在 0～ 50 μg/L内符合比尔定律。方法用于中草药及钢样中V(Ⅴ )的测定 ,结果与原子吸收法一致 ,加标回收率在 96%～ 1 0 5 % ,5次测定结果的RSD <3 5 %。  相似文献   

Measurement of a Peak in the Cosmic Microwave Background Power Spectrum from the North American Test Flight of Boomerang     

Mauskopf PD  Ade PA  de Bernardis P  Bock JJ  Borrill J  Boscaleri A  Crill BP  DeGasperis G  De Troia G  Farese P  Ferreira PG  Ganga K  Giacometti M  Hanany S  Hristov VV  Iacoangeli A  Jaffe AH  Lange AE  Lee AT  Masi S  Melchiorri A  Melchiorri F  Miglio L  Montroy T  Netterfield CB  Pascale E  Piacentini F  Richards PL  Romeo G  Ruhl JE  Scannapieco E  Scaramuzzi F  Stompor R  Vittorio N 《The Astrophysical journal》2000,536(2):L59-L62

We describe a measurement of the angular power spectrum of anisotropies in the cosmic microwave background (CMB) at scales of 0&fdg;3 to 5 degrees from the North American test flight of the Boomerang experiment. Boomerang is a balloon-borne telescope with a bolometric receiver designed to map CMB anisotropies on a long-duration balloon flight. During a 6 hr test flight of a prototype system in 1997, we mapped more than 200 deg(2) at high Galactic latitudes in two bands centered at 90 and 150 GHz with a resolution of 26&arcmin; and 16&farcm;5 FWHM, respectively. Analysis of the maps gives a power spectrum with a peak at angular scales of 1 degrees with an amplitude 70 μK(CMB).  相似文献   

Author Index     

R. De La Fuente Marcos  A. Nissar 《Earth, Moon, and Planets》2000,88(4):249-249

Authors Index

Author Index  相似文献   

基于SSA-MGF的BP神经网络多步预测模型   总被引：3，自引：2，他引：3  

李永华  金龙  缪启龙  刘德  高阳华 《南京气象学院学报》2005,28(4):549-555

采用奇异谱分析（Singular Spectrum Analysis，SSA）方法对标准化样本序列进行准周期信号分量重建，将重建序列构造均值生成函数（Mean Generating Function．MGF）延拓矩阵作为输入因子，原样本序列作为输出因子，构建BP神经网络多步预测模型。通过实际建模并与逐步回归等方法进行对比预测试验，结果表明，基于SSA-MGF的BP神经网络多步预测模型预测效果优于其他3种模型，说明SSA的去噪及BP神经网络预报模型对于提高预测准确率是相对有效的，是一种具有较高应用价值的多步预测方法。  相似文献   

Statistical assessment of trends and oscillations in rainfall dynamics: Analysis of long daily Italian series   总被引：1，自引：0，他引：1  

M. Cislaghi  C. De Michele  A. Ghezzi  R. Rosso 《Atmospheric Research》2005,77(1-4):188

Since the 18th century systematic measurements of rainfall have been collected in Italy. The daily rainfall series observed in Milan (1835–2001), Genoa (1833–2000), Bologna (1813–2001) and Palermo (1797–1999) are examples of available long rainfall records. These data series can help analyzing the evolution of precipitation. The present paper deals with long term evolution of: (i) annual rainfall amount; (ii) annual number of rainy events; (iii) intensity of rainfall, (iv) inter-annual rainfall partitioning, i.e. the duration of wet and dry periods, and (v) maximum annual values of daily rainfall amount, duration of wet and dry periods. The evolution is studied analyzing the first two order statistics and the 30-year return period quantiles via moving window analysis. Confidence intervals are introduced to check the statistical significance of the estimated statistics and quantiles. The results are compared with those provided by the traditional Mann-Kendall test. The analysis shows how the annual precipitation exhibits a negative trend in the first half of 20th century, with a subsequent positive trend in northern Italy (Genoa, Milan and Bologna). Conversely, the dataset for Palermo (southern Italy) displays only a negative trend. Because the number of precipitation episodes is found to decrease in the investigated period, the average rain rate is significantly increasing especially in northern Italy. This is also associated with shorter duration of rain episodes with an evident effect on rainfall extremes. Dry periods tend to be longer with increasing variability. The Mann-Kendall test and its progressive form have shown to be well suited for monotonic trend, but the confidence interval analysis, introduced here, is more appropriate if oscillations are significant.  相似文献   

面向对象的分析模型及其应用     

牛德力  毛国苗 《测绘学院学报》2000,17(2):111-114

介绍了Ｙｏｕｄｏｎ提出的面向对象分析（ＯＯＡ）模型,讨论了在系统分析的阶段难以使用ＯＯＡ的原因,提出了将ＯＯＡ与传统分析技术相结合的系统分析方法和实用步骤,以图库管理的系统分析为例讨论了这种方法的具体应用。  相似文献   

组件式软件及其在GIS开发中的应用   总被引：7，自引：0，他引：7  

牛德力  门葆红 《测绘学院学报》2000,17(4):265-268

介绍了组件技术的基本概念和原理,以图库管理系统为讨论了ＭａｐＸＯＣＸ控件的具体应用方法,少步骤和分发。  相似文献   

Integrity Monitoring of IGEX-98 Data,Part I: Availability     

N. F. Jonkman  K. De Jong 《GPS Solutions》2000,3(4):10-23

The International GLONASS Experiment 1998 (IGEX-98) was the first international tracking campaign of the Russian counterpart to the Global Positioning System (GPS), GLONASS. Started in October 1998, the campaign was originally scheduled to last for three months. However, the launch of additional GLONASS satellites and a widespread enthusiasm among the participants led to an indefinite continuation of the campaign on a “best effort” basis. At the Delft University of Technology, the data of six IGEX-98 stations have been analyzed in detail with integrity monitoring software, developed at the Department of Mathematical Geodesy and Positioning of the University. The software aims to detect outliers and slips in code and phase observations in real time. In addition, the software also allows the validation of the information contained in the broadcast navigation messages. The results of the IGEX-98 data analyses will be presented in a three-part series. In the second part, GLONASS outlier and slips statistics will be discussed, while in the third part the anomaly detection results of the GLONASS and GPS messages will be shown. In this first part of the series, however, the most basic of all statistics will be considered: a simple day-to-day count of the number of GLONASS and GPS observations. Although simple, this statistic yields a surprising amount of information both on the availability of the GLONASS satellites and on the peculiarities of some of the receiver makes participating in the IGEX-98 campaign. ? 2000 John Wiley & Sons, Inc.  相似文献   

Quantitative estimation of skin soil moisture with the Special Sensor Microwave/Imager   总被引：1，自引：0，他引：1  

Koen De Ridder 《Boundary-Layer Meteorology》2000,96(3):421-432

A physically based retrieval scheme is described toinfer near surface moisture content of bare soilpatches from time series of the Special SensorMicrowave/Imager (SSM/I) Polarisation DifferenceTemperature (PDT) at 19.35 GHz. The PDT is modelled asa function of soil moisture using Fresnel's relationsfor specular reflection at the air-soil boundary,together with a dielectric mixing model for themoisture-dependent soil dielectric constant. Theproblem of the specification of parameters describingatmospheric and soil roughness effects is avoided byconsidering temporal variations of the PDT. Theretrieval method is applied to the FIFE site for atwo-week period in summer, during which heavy rainfalloccurred on a dry upper soil. Although differences insensing depths made a rigorous validation impossible,remotely sensed soil moisture showed a high degree ofconsistency with ground measurements. An erroranalysis shows that the method is capable of providingan accuracy of approximately 20% of moisture contentat field capacity. Finally, it is demonstrated thatthe method is relatively insensitive to soil texturalcharacteristics when moisture content is scaled withfield capacity.  相似文献