In forest growing at any one site, the growth rate of an individual tree is determined principally by its size, which reflects its metabolic capacity, and by competition from neighboring trees. Competitive effects of ...In forest growing at any one site, the growth rate of an individual tree is determined principally by its size, which reflects its metabolic capacity, and by competition from neighboring trees. Competitive effects of a tree may be proportional to its size;such competition is termed ‘sym-metric’ and generally involves competition below ground for nutrients and water from the soil. Competition may also be ‘asymmetric’, where its effects are disproportionate to the size of the tree;this generally involves competition above ground for sunlight, when larger trees shade smaller, but the reverse cannot occur. This work examines three model systems often seen as exemplars relating individual tree growth rates to tree size and both competitive processes. Data of tree stem basal area growth rates in plots of even- aged, monoculture forest of blackbutt (Eucalyptus pilularis Smith) growing in sub-tropical eastern Australia were used to test these systems. It was found that none could distin-guish between size and competitive effects at any time in any one stand and, thus, allow quantification of the contribution of each to explaining tree growth rates. They were prevented from doing so both by collinearity between the terms used to describe each of the effects and technical problems involved in the use of nonlinear least-squares regression to fit the models to any one data set. It is concluded that quite new approaches need to be devised if the effects on tree growth of tree size and competitive processes are to be quantified and modelled successfully.展开更多
针对人脸识别中识别精度低的问题,提出一种基于深度学习的跨年龄人脸识别算法.该方法创新性地将方向梯度直方图(Histogram of Oriented Gradient,HOG)和中心对称局部二值模式(Center Symmetric Local Binary Pattern,CSLBPS)组合方法用...针对人脸识别中识别精度低的问题,提出一种基于深度学习的跨年龄人脸识别算法.该方法创新性地将方向梯度直方图(Histogram of Oriented Gradient,HOG)和中心对称局部二值模式(Center Symmetric Local Binary Pattern,CSLBPS)组合方法用于人脸图像特征提取,获得包含结构和强度信息的图像融合特征,然后使用二叉树对特征信息进行降维,降维特征作为深度信念网络的可视层输入量,弥补深度新信念网络无法达到图像局部特征要求的缺陷.通过训练好的深度网络模型对测试样本进行学习,在深度信念网络的最顶层对特征进行分类识别.实验结果表明,该方法能高精度实现人脸识别,且与其他方法比较,该方法性能优于其他方法,说明该方法具有可行性和有效性.展开更多
针对对称混合调制信号的识别问题,在单通道接收的条件下,对信号的频谱特性和幅度特征分析进行研究实现了10种双路对称混合信号的调制识别其中还包括性能优化的高阶APSK信号。首先提取8个特征参数,然后根据不同信号特征参数的差异设计分...针对对称混合调制信号的识别问题,在单通道接收的条件下,对信号的频谱特性和幅度特征分析进行研究实现了10种双路对称混合信号的调制识别其中还包括性能优化的高阶APSK信号。首先提取8个特征参数,然后根据不同信号特征参数的差异设计分类决策树。仿真结果表明,该算法计算量小能同时适用于多种混合调制信号的识别,在信噪比大于10 d B的条件下,具有良好的识别性能。同时,该算法不需要先验知识避免了复杂的预处理过程且算法对信号定时、相位偏差和频偏不敏感,具有较好的鲁棒性。展开更多
Building up graph models to simulate scale-free networks is an important method since graphs have been used in researching scale-free networks. One use labelled graphs for distinguishing objects of communication and i...Building up graph models to simulate scale-free networks is an important method since graphs have been used in researching scale-free networks. One use labelled graphs for distinguishing objects of communication and information networks. In this paper some methods are given for constructing larger felicitous graphs from smaller graphs having special felicitous labellings, and some network models are shown to be felicitous.展开更多
文摘In forest growing at any one site, the growth rate of an individual tree is determined principally by its size, which reflects its metabolic capacity, and by competition from neighboring trees. Competitive effects of a tree may be proportional to its size;such competition is termed ‘sym-metric’ and generally involves competition below ground for nutrients and water from the soil. Competition may also be ‘asymmetric’, where its effects are disproportionate to the size of the tree;this generally involves competition above ground for sunlight, when larger trees shade smaller, but the reverse cannot occur. This work examines three model systems often seen as exemplars relating individual tree growth rates to tree size and both competitive processes. Data of tree stem basal area growth rates in plots of even- aged, monoculture forest of blackbutt (Eucalyptus pilularis Smith) growing in sub-tropical eastern Australia were used to test these systems. It was found that none could distin-guish between size and competitive effects at any time in any one stand and, thus, allow quantification of the contribution of each to explaining tree growth rates. They were prevented from doing so both by collinearity between the terms used to describe each of the effects and technical problems involved in the use of nonlinear least-squares regression to fit the models to any one data set. It is concluded that quite new approaches need to be devised if the effects on tree growth of tree size and competitive processes are to be quantified and modelled successfully.
文摘针对人脸识别中识别精度低的问题,提出一种基于深度学习的跨年龄人脸识别算法.该方法创新性地将方向梯度直方图(Histogram of Oriented Gradient,HOG)和中心对称局部二值模式(Center Symmetric Local Binary Pattern,CSLBPS)组合方法用于人脸图像特征提取,获得包含结构和强度信息的图像融合特征,然后使用二叉树对特征信息进行降维,降维特征作为深度信念网络的可视层输入量,弥补深度新信念网络无法达到图像局部特征要求的缺陷.通过训练好的深度网络模型对测试样本进行学习,在深度信念网络的最顶层对特征进行分类识别.实验结果表明,该方法能高精度实现人脸识别,且与其他方法比较,该方法性能优于其他方法,说明该方法具有可行性和有效性.
文摘针对对称混合调制信号的识别问题,在单通道接收的条件下,对信号的频谱特性和幅度特征分析进行研究实现了10种双路对称混合信号的调制识别其中还包括性能优化的高阶APSK信号。首先提取8个特征参数,然后根据不同信号特征参数的差异设计分类决策树。仿真结果表明,该算法计算量小能同时适用于多种混合调制信号的识别,在信噪比大于10 d B的条件下,具有良好的识别性能。同时,该算法不需要先验知识避免了复杂的预处理过程且算法对信号定时、相位偏差和频偏不敏感,具有较好的鲁棒性。
文摘Building up graph models to simulate scale-free networks is an important method since graphs have been used in researching scale-free networks. One use labelled graphs for distinguishing objects of communication and information networks. In this paper some methods are given for constructing larger felicitous graphs from smaller graphs having special felicitous labellings, and some network models are shown to be felicitous.
