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I. ISTIARTO W.H. GRAF Res. Asst. Lab. de recherches hydrauliques Ecole Polytechnique Federale Lausanne Switzerland. E-mail: adhy.kurniawan@epfl.ch or istiarto@tsipil.ugm.ac.id Prof Lab. de recherches hydrauliques Ecole Polytechnique Federal 《国际泥沙研究》2001,(4)
1 INTRODUCTION'LOcal scour around a pier is a result of the interatiOn amongst the pier, the aPproach flow and theerodible bed. The Presence of a pier results in a stagnation pressure build-up in front of the pier and athree-dimensional tUrbulent flow echaracterized by the downward flow ahead of the pier and the so-called horseshoe vortex along the base of the Pier forms itself The flow modifies the erothe bed inthe vicinity of the pier when local scour takes place (Graf and AJhnakar l… 相似文献
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There are many chemical products where product conformity is decided upon by qualitative humanjudgements of overall product quality.Nowadays,quantitative instrumentally determined qualityparameters become available which are intended to replace such qualitative judgements by means ofautomatic decision rules using multivariate specification limits.Six classification methods to derive suchlimits are compared in terms of their power to predict corresponding human judgements on overall colorconformity of 17 dyestuffs based on historical quality data.Standard statistical classification methodsturned out to be unacceptable for the routine generation of decision rules because of the frequent distinctsuboptimality of their predictive power.Instead,a simple non-statistical classification method utilizinga priori knowledge about the underlying data structure yielded uniformly satisfactory decision rules. 相似文献
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C.WEIHS Mathematical Applications Information Services R-.Z. CIBA-GEIGY Ltd. CH- Basel Switzerland 《地理学报(英文版)》1993,(5)
Exploratory data analysis(EDA)is a toolbox of data manipulation methods for looking at data to seewhat they seem to say,i.e.one tries to let the data speak for themselves.In this way there is hope thatthe data will lead to indications about'models'of relationships not expected a priori.In this respect EDAis a pre-step to confirmatory data analysis which delivers measures of how adequate a model is.In thistutorial the focus is on multivariate exploratory data analysis for quantitative data using linear methodsfor dimension reduction and prediction.Purely graphical multivariate tools such as 3D rotation andscatterplot matrices are discussed after having introduced the univariate and bivariate tools on which theyare based.The main tasks of multivariate exploratory data analysis are identified as'search for structure'by dimension reduction and'model selection'by comparing predictive power.Resampling is used tosupport validity,and variables selection to improve interpretability. 相似文献
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Dr. M. C. Kavanaugh Dr. U. Zimmermann Mrs. A. Vagenknecht Dipl.-Ing. Eidg. Anstalt für Wasserversorgung. Abwasserreinigung und Gew?sserschutz CH- Dübendorf Switzerland 《Aquatic Sciences - Research Across Boundaries》1977,39(1):86-98
Use of a Zeiss Micro-Videomat electronic image analyzer for routine measurements of size distributions of particles found in natural waters greater than 0.3 μm has been investigated. Staining of particles with a solution of Gentiana-violet eliminated the multiple-count problem which has frustrated earlier attempts to use image analyzers for quantitative phytoplankton work. Concentration of samples from the lake water column was successfully achieved with an impact centrifuge. Losses of inorganic particles indicate that the centrifuge method must be evaluated on an individual case basis. Precision and accuracy of the Zeiss Micro-Videomat using either sedimentation (Utermöhl) or centrifugation for sample concentration were satisfactory for particles larger than 1 μm. The system appears promising for routine surveillance of raw water quality at water treatment plants, and performance of unit processes used for particulate removal, as well as for specific investigations of ecological phenomena in natural waters. 相似文献
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