树木修剪量化考核指标探讨

通过多年一体化教学实践，总结出树木修剪实习考核的量化指标，适合于园林绿化专业学生，便于合理地评价树木修剪的效果和学生操作水平。     

污染环境中两种群的生存阈值

本文利用积分均值法研究了伪酱油果蝇和锯形果蝇在污染环境中的数学模型。给出了两种群的生存闽值。     

岩石扩容现象与超声横波特征参数相互关系研究评述

介绍了岩石扩容现象与超声皮特征参数相互关系相关专业领域研究的现状及其应用，在用横波速度最大值（Vsmax）来分析岩石微裂纹初始扩展时的应力值（应力门槛值）新方法的基础上，建议利用主动的人工横波震源，应力门槛值、Vsmax后的横波速度值与岩石裂纹加速发展的同步减小特性，更深入地进入地震破裂丛集及前兆特征的研究，有可能建立地震和地质灾害性预报的新方法，并提出利用利用传统方法研究岩石扩容机理，应力门槛值，泊松比等的同时，进行岩石扩容现象，声发射和超声波横波等特性参相互关系研究的新思路。     

极值VaR度量的一个新方法研究

在险价值是度量市场风险的一种普遍使用的工具，是市场风险度量的基石。本文应用统计学中的极值理论与泊松过程于VaR的计算。这种新方法是VaR度量方法中最稳健的方法之一。     

多维门限GARCH模型的平稳遍历性

给出了多维双门限自回归GARCH模型；该模型是一维双门限自回归GARCH模型在多维情况的一种推广，并且讨论了多维双门限自回归GARCH模型存在严平稳遍历性的充分必要条件。     

数字图象的二值化处理技术探究

分析了数字图象二值化处理的特点，提供了几种二值化处理技术，并对这些算法进行了测试与比较，最后根据实践应用对二值化处理中的动态阈值的选取策略等相关技术作出了阐述。     

Energy flow and community structure in freshwater ecosystems

The goal of this article is twofold: 1) It aims at providing an overview on some major results obtained from energy flow studies in individuals, populations, and communities, and 2) it will also focus on major mechanisms explaining community structures. The basis for any biological community to survive and establish a certain population density is on the one hand energy fixation by primary producers together with adequate nutrient supply and the transfer of energy between trophic levels (bottom-up effect). On the other hand, predator pressures may strongly control prey population densities one or more trophic levels below (top-down effect). Other interpopulation effects include competition, chemical interactions and evolutionary genetic processes, which further interact and result in the specific structuring of any community with respect to species composition and population sizes.     

用于瞳孔序列图像分析的实时轮廓检测和参数提取

本文介绍一种医用图像分析系统．该系统连续获取瞳孔图像,根据对图像序列的某些先验知识自动确定门限．在此基础上进行快速边缘检测,并自动修补缺损的目标轮廓．在判定所得轮廓有效后计算目标面积．若数据无效则自动重新采样．序列图像观测结束后对间隔不均匀的数据进行内插校正．系统所提供的分析结果可用于临床和医学研究     

Forecasting in the presence of level shifts

This article addresses the problem of forecasting time series that are subject to level shifts. Processes with level shifts possess a nonlinear dependence structure. Using the stochastic permanent breaks (STOPBREAK) model, I model this nonlinearity in a direct and flexible way that avoids imposing a discrete regime structure. I apply this model to the rate of price inflation in the United States, which I show is subject to level shifts. These shifts significantly affect the accuracy of out‐of‐sample forecasts, causing models that assume covariance stationarity to be substantially biased. Models that do not assume covariance stationarity, such as the random walk, are unbiased but lack precision in periods without shifts. I show that the STOPBREAK model outperforms several alternative models in an out‐of‐sample inflation forecasting experiment. Copyright © 2005 John Wiley & Sons, Ltd.     

基于盲签名的电子选举方案的改进

在分析Sensus电子投票系统的基础上,针对该系统的不足之处提出了相关的改进意见,并改进设计一个可用于互联网大规模投票的电子选举方案,该方案采用了阈值、盲签名、验证序列号等思想,使得本协议方案在保持了原有方案的各种优点的同时,增强了电子投票系统的安全性和公正性,并具有较高的效率,是一个实用的电子投票方案。