黑龙江省乡土彩叶植物应用现状及筛选评价

对彩叶树种在城市园林绿化中的研究进展、应用状况进行基本概述,了解目前国内彩叶树种在园林绿化中的发展趋势;同时对黑龙江省城市园林绿化中彩叶树种的应用状况进行分析,明确了黑龙江省彩叶树种在品种应用方面的匮乏,进而结合我省乡土树种抗性强、变异小、易存活等特点开发本土彩叶植物资源,结合层次分析方法筛选出具有较高观赏价值的秋叶观...     

Calibration to American options: numerical investigation of the de-Americanization method

American options are the reference instruments for the model calibration of a large and important class of single stocks. For this task, a fast and accurate pricing algorithm is indispensable. The literature mainly discusses pricing methods for American options that are based on Monte Carlo, tree and partial differential equation methods. We present an alternative approach that has become popular under the name de-Americanization in the financial industry. The method is easy to implement and enjoys fast run-times (compared to a direct calibration to American options). Since it is based on ad hoc simplifications, however, theoretical results guaranteeing reliability are not available. To quantify the resulting methodological risk, we empirically test the performance of the de-Americanization method for calibration. We classify the scenarios in which de-Americanization performs very well. However, we also identify the cases where de-Americanization oversimplifies and can result in large errors.     

Option pricing with the control variate technique beyond Monte Carlo simulation

Although mostly used alongside Monte Carlo simulation, the control-variate (CV) technique can be applied to other numerical algorithms in option pricing. This paper studies the conditions under which a numerical method (simulation-based or not) can benefit from the CV technique and what approximators can serve as CVs. We demonstrate the ideas with Carr and Madan’s Fourier transform-based algorithm, convolution-based pricing algorithms, and classic binomial trees. Numerical results are provided to show that the CV-enhanced versions are more efficient than the original algorithms.     

On the determinants of happiness: a classification and regression tree (CART) approach

This article studies the determinants of the individual’s subjective well-being by applying a classification and regression tree (CART) analysis to data from the Survey on Household Income and Wealth (SHIW) provided by the Bank of Italy. The results support the primary importance of economic conditions but show that their effect is heterogeneously dependent on other individual characteristics.     

“任务驱动教学法”在高职《园林树木》课程改革中的运用

《园林树木》课程是园林技术专业主干课程之一。文章针对于课程教学过程中存在的问题进行分析研究,提出了基于工作任务驱动法在教学中的实践,指出了课程改革思路,以学定教,突出能力培养,改革教学组织和采取的主要措施。     

The risk to the public of tree fall

This paper is concerned with the quantification of tree risk to the British public as a whole; with factors which influence actual risk, such as location and meteorology; and with perceived risk which can be a driver of control actions. The emergent risk is found to be very small and the perceptual factors examined do not support anything other than a proportionate approach to safety management. Policy implications are discussed.     

树文化之再思考

“树化”是指以树为载体的社会化现象。树化有宗教形态、社会形态、民俗形态、美学形态等不同形态之分。促进树与化的互动发展,实现树与化的共生共荣,是我们应该弘扬的先进树化的发展方向。     

Data accuracy's impact on segmentation performance: Benchmarking RFM analysis,logistic regression,and decision trees

Companies greatly benefit from knowing how problems with data quality influence the performance of segmentation techniques and which techniques are more robust to these problems than others. This study investigates the influence of problems with data accuracy – an important dimension of data quality – on three prominent segmentation techniques for direct marketing: RFM (recency, frequency, and monetary value) analysis, logistic regression, and decision trees. For two real-life direct marketing data sets analyzed, the results demonstrate that (1) under optimal data accuracy, decision trees are preferred over RFM analysis and logistic regression; (2) the introduction of data accuracy problems deteriorates the performance of all three segmentation techniques; and (3) as data becomes less accurate, decision trees retain superior to logistic regression and RFM analysis. Overall, this study recommends the use of decision trees in the context of customer segmentation for direct marketing, even under the suspicion of data accuracy problems.     

大叶茶树无性系选育有关问题的分析探讨

本文从多年的研究实践中总结、概述高产优质大叶茶树无性系的选育和方法,从理论上探讨茶树选育的鉴定标准,并提出了今后茶树优良无性系选育工作的方向及展望。