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891.
This paper considers univariate and multivariate models to forecast monthly conflict events in the Sudan over the out‐of‐sample period 2009–2012. The models used to generate these forecasts were based on a specification from a machine learning algorithm fit to 2000–2008 monthly data. The model that includes previous month's wheat price performs better than a similar model which does not include past wheat prices (the univariate model). Both models did not perform well in forecasting conflict in a neighborhood of the 2012 ‘Heglig crisis’. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
892.
Piotr Błaszczyk Vladimir Kanovei Karin U. Katz Mikhail G. Katz Semen S. Kutateladze David Sherry 《Foundations of Science》2017,22(4):763-783
Abraham Robinson’s framework for modern infinitesimals was developed half a century ago. It enables a re-evaluation of the procedures of the pioneers of mathematical analysis. Their procedures have been often viewed through the lens of the success of the Weierstrassian foundations. We propose a view without passing through the lens, by means of proxies for such procedures in the modern theory of infinitesimals. The real accomplishments of calculus and analysis had been based primarily on the elaboration of novel techniques for solving problems rather than a quest for ultimate foundations. It may be hopeless to interpret historical foundations in terms of a punctiform continuum, but arguably it is possible to interpret historical techniques and procedures in terms of modern ones. Our proposed formalisations do not mean that Fermat, Gregory, Leibniz, Euler, and Cauchy were pre-Robinsonians, but rather indicate that Robinson’s framework is more helpful in understanding their procedures than a Weierstrassian framework. 相似文献
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下世纪初,只要看一下戴在自己手腕上的微型电话,你就会知道你的朋友在呼叫你。引起变化的方式有许许多多种。有的人采取的是流血的暴力行动,另一些人通过有说服力的辩论来改变我们的生活。而电气工程与计算机科学教授克拉克·尼因则希望通过改变我们的通讯方式来使我们的生活发生革命性的变化。尤其是,他的目的在于缩小移动电话和收音机的尺寸,直到它们变得小到可以安装在手表内或者像最近的电影“星球旅行”中所描述的科幻通讯器可以像缝在衣服上的纽扣那样小为止。在一个微型器件上将一种发射器和接收器的线路组合在一起构成一种发射… 相似文献
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This article presents a novel neural network?based approach to the intra?day forecasting of call arrivals in call centres. We apply the method to individual time series of arrivals for different customer call groups. To train the model, we use historical call data from three months and, for each day, we aggregate the call volume in 288 intervals of 5 minutes. With these data, our method can be used for predicting the call volume in the next 5?minute interval using either previous real data or previous predictions to iteratively produce multi?step?ahead forecasts. We compare our approach with other conventional forecasting techniques. Experimental results provide factual evidence in favour of our approach. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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An Wang Feng Du Yongjun Zhang David Graf Bin Shen Ye Chen Yang Liu Michael Smidman Chao Cao Frank Steglich Huiqiu Yuan 《科学通报(英文版)》2021,(14):1389-1394
Ferromagnetic quantum critical points were predicted to be prohibited in clean itinerant ferromagnetic systems,yet such a phenomenon was recently revealed in Ce... 相似文献
900.
Habitat use and food selection data were collected for deer mice ( Peromyscus maniculatus ), montane voles ( Microtus montanus ), Ord's kangaroo rats ( Dipodomys ordii ), and Townsend's ground squirrels ( Spermophilus townsendii ) near a sagebrush ( Artemisia tridentata )/crested wheatgrass ( Agropyron cristatum ) interface in southeastem Idaho. Significantly more captures occurred in the native sagebrush habitat than in areas planted in crested wheatgrass or in disturbed sites. Crested wheatgrass, a prolific seed producer, still accounted for over 30% of the total captures. Montane voles and Townsend's ground squirrels (during periods of aboveground activity) used the crested wheatgrass habitat throughout the summer, while deer mice and, Ord's kangaroo rats exhibited heavy use after seed set. 相似文献