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141.
为有利土壤测试工作的开展,促进测土配方施肥技术的推广,对土壤速测技术提出一些基本观点:应用区域主要是乡镇一级;对测试速度要求当天拿结果即可;对准确性适度要求;土壤样仍以风干样品为好;土壤样品粒径统一取0.30 mm。并对速测项目,土壤浸提方法,水、化学试剂的选用提出意见。 相似文献
142.
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145.
The prediction of crack growth in bonded joints under cyclic-fatigue loading I. Experimental studies
H. Hadavinia A. J. Kinloch M. S. G. Little A. C. Taylor 《International Journal of Adhesion and Adhesives》2003,23(6):449-461
The performance of adhesively-bonded joints under monotonic and cyclic-fatigue loading has been investigated using a fracture-mechanics approach. The joints consisted of an epoxy film adhesive which was employed to bond aluminium-alloy substrates. The effects of undertaking cyclic-fatigue tests in (a) a ‘dry’ environment of 55% relative humidity at 23°C, and (b) a ‘wet’ environment of immersion in distilled water at 28°C were investigated. In particular, the influence of employing different surface pretreatments for the aluminium-alloy substrates was examined. In addition, single-lap joints were tested under cyclic fatigue loading in the two test environments, and a back-face strain technique has been used which revealed that crack propagation, rather than crack initiation, occupied the dominant proportion of the fatigue lifetime of the single-lap joints. In Part II, the data obtained in the present Part I paper will be employed to predict theoretically the lifetime of the adhesively-bonded single-lap joint specimens. 相似文献
146.
针对钢铁材质浮标的ADCP水文监测系统内置罗经受船磁力影响,导致流向测验出现偏差的问题,通过2009—2011年徐六泾水文站定线比测大、中潮水文测验的实测资料,分析采用垂直于断面的方位角作为流向(流向不修正)和采用断面各垂线实测平均流向作为流向(流向修正)两种情况下钢铁材质浮标对ADCP水文监测系统流量测验精度和流量、潮量计算的影响。结果表明:无论是否修正流向,计算得到涨落潮流量、潮量以及全潮下泄潮量和走航式ADCP定线比测的实测资料相比,误差均较小,精度都很高;在流量和潮量计算时,可以对钢铁材质浮标ADCP流向不做修正。 相似文献
147.
为了深入研究山西省孝义市气候变化特征,采用Mann-Kendall检验、滑动T检验及Morlet小波变换等方法对孝义市1975-2015年气候要素进行趋势估计、突变检验、周期分析及发展趋势预测。结果表明:近40年来,孝义市年平均气温呈显著上升趋势,突变年份为1996年,存在32、9 a长周期;年降雨量呈不显著下降趋势,突变年份为1990年,存在32、6 a长周期;年蒸发量呈显著性上升趋势,突变年份为1997年,存在32、10 a长周期;年平均相对湿度呈显著下降趋势,突变年份为1982、2003年,存在15、32 a长周期。孝义市1975-2015年年代际气候经历了"冷湿-暖湿-暖干"的变化过程,预测全境2017-2030年年代际气候将经历"冷湿-暖干"的变化过程。 相似文献
148.
Aziz Rezig Tinh Nguyen David Martin Lipiin Sung Xiaohong Gu Joan Jasmin Jonathan W. Martin 《Journal of Coatings Technology and Research》2006,3(3):173-184
The relationship between chemical degradation and thickness loss of an unpigmented, non UV-stabilized, crosslinked amine-cured
epoxy coating exposed to three UV conditions was investigated. Spin-coated samples having a thickness of approximately 7 μm
on an Si substrate were prepared from a stochiometric mixture of a bisphenol A epoxy resin and a tetra-functional amine curing
agent. Samples were exposed outdoors and to two accelerated laboratory UV environments. Chemical degradation and thickness
loss were measured by transmission Fourier transform infrared spectroscopy (FTIRS) and laser scanning confocal microscopy
(LSCM), respectively. In addition, surface roughness and morphological changes were measured by atomic forcemicrosocopy (AFM)
and LSCM. Substantial chemical degradation, thickness loss, and morpholocal changes occurred in the exposed films, and the
rate of chemical degradation was greater than that due to the thickness loss. This additional chemical loss was attributed
to an inhomogeneous degradation process in which nanoscale localized depressions initiate at certain sites on the surface,
which then enlarge and deepen with exposure time. The results of this study provide a better understanding of the degradation
mechanism and should lead to the development of scientific-based models for predicting the service life of crosslinked amine-cured
epoxy coatings.
Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago,
IL 相似文献
149.
Case-based reasoning (CBR) is one of the main forecasting methods in business forecasting, which performs well in prediction and holds the ability of giving explanations for the results. In business failure prediction (BFP), the number of failed enterprises is relatively small, compared with the number of non-failed ones. However, the loss is huge when an enterprise fails. Therefore, it is necessary to develop methods (trained on imbalanced samples) which forecast well for this small proportion of failed enterprises and performs accurately on total accuracy meanwhile. Commonly used methods constructed on the assumption of balanced samples do not perform well in predicting minority samples on imbalanced samples consisting of the minority/failed enterprises and the majority/non-failed ones. This article develops a new method called clustering-based CBR (CBCBR), which integrates clustering analysis, an unsupervised process, with CBR, a supervised process, to enhance the efficiency of retrieving information from both minority and majority in CBR. In CBCBR, various case classes are firstly generated through hierarchical clustering inside stored experienced cases, and class centres are calculated out by integrating cases information in the same clustered class. When predicting the label of a target case, its nearest clustered case class is firstly retrieved by ranking similarities between the target case and each clustered case class centre. Then, nearest neighbours of the target case in the determined clustered case class are retrieved. Finally, labels of the nearest experienced cases are used in prediction. In the empirical experiment with two imbalanced samples from China, the performance of CBCBR was compared with the classical CBR, a support vector machine, a logistic regression and a multi-variant discriminate analysis. The results show that compared with the other four methods, CBCBR performed significantly better in terms of sensitivity for identifying the minority samples and generated high total accuracy meanwhile. The proposed approach makes CBR useful in imbalanced forecasting. 相似文献
150.
将地面站点观测的降水数据作为基准降水数据,评估汛期热带降雨观测计划(TRMM)降水产品3B42研究型数据(V7)与实时降水数据(RT)的日以及月尺度数据在黑龙江省乌苏里江流域的时空精度。结果表明:在时间尺度上,TRMM 3B42V7与3B42RT的日降水数据与站点降水数据相比,均系统性偏小,且相关性不是很好;相对而言,3B42RT与站点数据的偏差程度较小,相关性较好;月尺度数据与日尺度数据相比,月数据精度均有很大提高,且2种产品数据精度相差不大;在空间尺度上,TRMM 3B42V7和3B42RT都能较好地展现乌苏里江流域降水的空间分布特征。针对评估结果,使用加法和乘法模型对TRMM 3B42V7和3B42RT的月降水数据进行修正。修正后,2种TRMM卫星降水产品的月降水数据精度均有提高,并且加法模型修正效果更好。因此,可选取加法模型修正后的3B42RT月尺度降水数据用于汛期乌苏里江流域的相关水文研究。 相似文献