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41.
积雪含水率是雪层中液态水的含量,也是积雪出流、产流的关键指标,对积雪含水率的研究对春季融雪产流及融雪型洪水有现实意义。借助美国ASD地物光谱仪和Snow Folk积雪特性仪获取原始数据,并利用SPSS19.0和Excel等统计软件对数据进行分析、处理,并利用这些数据进行制图、数据综合,建立雪表层的地物光谱特征预测模型。结果表明:积雪的光谱特征曲线由于在可见光和近红外由于吸收呈现出若干波谷;地物光谱特征与积雪表层含水率存在负相关关系,且随着波长的增加这种负相关关系变化明显,并在可见光和近红外形成三个相关关系的极小值;构建雪层含水率的地物光谱反射率模型,可见光范围内,在350 nm时的模型精度较高,能够达到75.9%,预测值和实测值拟合程度高,在近红外波段内,1 204 nm建模的模拟精度最高。 相似文献
42.
Adriano Vanni Vincenzo Pellegrino Roberta Gamberini Adelaide Calabria 《International journal of environmental analytical chemistry》2013,93(4):349-355
Abstract HANDBOOK FOR ESTIMATING PHYSICOCHEMICAL PROPERTIES OF ORGANIC COMPOUNDS, by M. Reinhard and A. Drefal, 228 pages, J. Wiley, New York (1999). ISBN 0—471—172634. UK £ 210.00 THE CHEMISTRY OF POLLUTION, by G. Fellenberg, 192 pp. J. Wiley & Sons, Chichester, U.K. (1999). ISBN 0—471—980889. UK£ 24,95. NATURAL ATTENUATION OF FUELS AND CHLORINATED SOLVENTS IN THE SUBSURFACE, by T.H. Wiedemeier, H.S. Rifai, C.J. Newell and J.T. Wilson, 617 pages, J. Wiley, New York (1999). ISBN 0—471—19749—1. UK £ 58.50 UNDERSTANDING OUR ENVIRONMENT, 3rd, edition, edited by R.M. Harrison, 445 pages, The Royal Society of Chemistry, Cambridge (UK) (1999). ISBN 0—85404—584—8. UK£ 19.95 ENDOCRINE DISRUPTING CHEMICALS, Vol. 12 of Issues in Environmental Science and Technology, edited by R.E. Hester and R.H. Harrison, 152 pages, Royal Society of Chemistry, Cambridge (U.K.) (1999). ISBN 0—85404—255—5. UK£ 25,00 METHOD PERFORMANCE STUDIES FOR SPECIATION ANALYSIS. by P. Quevauviller, 271 pages, The Royal Society of Chemistry, Cambridge (U.K.) (1998). ISBN 0—85404—467—1. UK£ 59.50 GLOBAL AQUATIC AND ATMOSPHERIC ENVIRONMENT, by H.D. Kumar and D.P. Häder, 393 pages, Springer, Berlin (1999). ISBN 3—540—65369—4. USD 229.00 BIOACCUMULATION. New Aspects and Developments, edited by B. Beek, 284 pages, Springer, Heidelberg, 2000. ISBN 3—540—62575. USD 143.00 INTERLABORATORY STUDIES AND CERTIFIED REFERENCE MATERIALS FOR ENVIRONMENTAL ANALYSIS. The BCR approach, by Ph. Quevauviller and E.A. Maier, 558 pages, Elsevier Science, Amsterdam NL, (1999). ISBN 0—444—82389—1. USD 251.50 (Euro 224.62). 相似文献
43.
Jan L. Giesbrecht Paul Smith Theo A. Tervoort 《Journal of polymer science. Part A, Polymer chemistry》2010,48(13):1543-1551
In this study, small-scale model skis running down a Nordic ski track were used to investigate the tribological properties of polymer ski soles of a wide range of chemical compositions and surface structures on snow at temperatures of −2 to −4 °C. It was found that ski soles consisting of smooth hydrophilic films of an arithmetical mean surface roughness of less than 0.2 μm experience a considerably higher friction with snow than flat hydrophobic films indicating that for such soles, capillary bridging of the lubricating water film between the snow and the ski base is the dominating friction mechanism. An optimum surface roughness of the ski soles was detected —in the range of 0.2–1 μm. At this surface roughness, sliders are always fast, essentially independent of chemical composition of the ski sole and surface topology. At higher surface roughness, it was found that friction between polymer and snow increases again, especially for structured surfaces that are not aligned in the gliding direction. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1543–1551, 2010 相似文献
44.
对北半球1978-2007年1月6日-2月4日逐日500 hPa高度场资料带通滤波,得到10-30 d 时间尺度分量,结合经验正交函数分解方法(empirical orthogonal function, EOF)提取出气候态基底.同样滤波北半球2008年1月冰冻雨雪事件的逐日实况资料,并将其投影到气候态基底上,利用各贡献率作为考察该EOF分量对原场的影响指标. 从10-30 d延伸期预报的角度提取稳定分量进行诊断分析,探讨影响此次天气过程的主要因素.通过贡献率分析方法把10-30 d延伸期稳定分量划分为气候态稳定分量和异常型稳定分量两个部分.结果表明:气候态稳定分量在我国南方2008年1月冰冻雨雪事件中占主体地位,异常型稳定分量相当于在气候态稳定分量的基础上叠加的扰动值, 但异常型稳定分量在本次过程中的作用不能忽视,甚至起到关键性的作用, 并且与实况距平在太平洋地区整体环流形势有较好的对应.这些结论加深了对10-30 d 时间尺度可预报性的认识,为10-30 d延伸期预报提供了一种新的思路和解决问题的途径. 相似文献
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We describe the effect of ground blizzards and blowing snow on millimeter wave scintillation spectra at 116 and 230 GHz. During snowstorms, multipath propagation can occur for various reasons. Whatever the reason for the multipath, it will affect the scintillation spectrum. Enhancement of the scintillation spectrum is observed at both low and high temporal frequencies. In some cases, two additional corner frequencies are evident at the high-frequency end of the scintillation spectrum. The method of obtaining the cross-path wind component fails when the wind is nearly parallel to the propagation path. 相似文献
48.
L. I. Fedoseev I. V. Kuznetsov N. K. Polova A. A. Shvetsov 《International Journal of Infrared and Millimeter Waves》1982,3(6):917-927
Equipment and methods used for measuring the apparent temperature of snow cover in high mountains is described. The spectrum of dry snowpack emission in the wavelength region 0.85÷1.3 mm is obtained. The dependence of the apparent temperature of snow cover on the atmospheric optical depth is determined. It is shown that in the first approximation the snow cover emission is described by the Lambert law and the snow albedo is within 0.6÷0.67. 相似文献
49.
用格林函数法计算圆柱腔中单荷电层的空间电荷场,分析在圆柱腔漂移管中的虚阴极时间相关行为。求出在非相对论情形下极限电荷q_L的表达式,对不同电荷值、荷电层的位置与速度随时间变化关系进行数值计算分析。给出了虚阴极直观的物理图象。 相似文献
50.
《Analytical letters》2012,45(2):481-492
Abstract A voltammetric method for the determination of iron at detection limit of 4 μg/l is described, using the catalytic current of the reduction of the Fe(III)-triethanolamine (TEA) complex in the presence of bromate ions. the determination was performed at a mercury hanging drop electrode without preconcentration, using the TEA alkaline solution as a supporting electrolyte and the differential pulse technique. A peak current for the Fe(III)-TEA catalytic reduction was observed at a potential of-1.0 V (Ag/AgCl saturated electrode). the influence of TEA, BrO3 and NaOH concentrations on the peak height was studied. It was found that a 100-fold excess of Mn, a 50-fold excess of Cr(VI) and Zn did not interfere in the determination. This method was applied to the determination of iron in water, snow and waste water samples. 相似文献