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1.
《计算机科学与探索》2016,(8):1176-1183
在统计机器学习的研究中,研究者常常通过定量实验来对照基于交叉验证的分类算法的F1度量,为了得到统计可信的结论,估计它的不确定性是非常重要的。特别地,组块3×2交叉验证方法被大量理论和实验验证了它的性能优于诸如标准K折交叉验证的其他常用交叉验证方法。为此,理论上研究了基于组块3×2交叉验证的F1度量的方差。方差的结构表明它由块方差、块内协方差和块间协方差三部分组成,从而说明了广泛使用的样本方差估计可能严重地低估或高估真实的方差。通过条形图方法在模拟和真实数据上进行实验,验证了上述理论结果,实验结果表明块内、块间协方差和块方差是同阶的,块内和块间相关性是不可忽略的。  相似文献   

2.
针对Markowitz均值-方差模型的不足,结合文献[1]算法提出了一种基于改进免疫遗传算法的证券组合投资策略,它克服了均值一方差模型的收益率必须服从正态分布的局限,并通过将投资收益率、风险损失和风险报酬三者分开度量,明晰了三者的关系。通过引入偏好系数加权法将上述三者进行权衡。仿真结果揭示了风险报酬和风险损失呈线性关系,得到了较好的效果。  相似文献   

3.
在混合线性模型中估计方差分量,最广泛应用的方法是极大似然(ML)法和约束极大似然(REML)法.从数理统计理论的高度来看,这些方法相当完美,但从数值计算的角度来看,却比较繁琐.为克服计算上的困难,在Oefversten[1]关于推导检验方差分量变换工作的基础上,我们提出了一种新的所谓“层三角变换法”。  相似文献   

4.
在传统的机器学习中,模型选择常常是直接基于某个性能度量指标的估计本身进行,没有考虑估计的方差,但是这样的忽略极有可能导致错误模型的选择。于是考虑在分类模型选择研究中添加方差的信息的方法,以提高所选模型的泛化能力,即将泛化误差性能度量指标的组块3×2交叉验证估计的方差估计作为正则化项添加到传统模型选择准则中,提出了一种新的方差正则化的分类模型选择准则。模拟和真实数据实验验证了在分类模型选择问题中,提出的模型选择准则相比传统方法选到正确分类模型的概率更大,验证了方差在模型选择中的重要性以及提出的模型选择准则的有效性。进一步,理论上证明了在二分类问题的模型选择中,该模型选择准则具有选择的一致性。  相似文献   

5.
一种新的Gabor优化选择检测算法及应用   总被引:1,自引:1,他引:0       下载免费PDF全文
针对基于Gabor小波的布匹瑕疵检测运算量大,准确率较低等问题,提出了一种新的优化选择算法,即均值归一化方差算法。布匹瑕疵图像通过多通道Gabor小波;分别计算各通道滤波图像的均值和方差;计算方差与均值的比值,选择比值最大的通道作为优化选择通道。考虑到布匹瑕疵主要表现为经向与纬向瑕疵,因此基于该算法设计了1×2二维Gabor小波布匹瑕疵自动检测系统,降低了运算量,提高了准确率,达到了93%。  相似文献   

6.
关于线性特征系数的几个问题   总被引:1,自引:0,他引:1  
本文研究了系统具有线性特征系数的条件。在指出文献[1]、[2]错误的同时,提出了系统具有全部线性特征系数的一个充分条件,并且证明了文献[1]的充分条件是这个充分条件的特殊情况。  相似文献   

7.
光纤陀螺Allan方差零偏不稳定性表征了光纤陀螺的1/f噪声或其它低频漂移,表征了光纤陀螺在惯性导航系统中的应用性能。因此,对Allan方差零偏不稳定性进行研究具有重要意义。本文对Allan方差零偏不稳定性进行了理论分析和实验验证,并采用了提高Allan方差零偏不稳定性的技术措施。测试结果表明:该技术措施可以明显提高光纤陀螺Allan方差零偏不稳定性。  相似文献   

8.
论文在研究现有访问控制方法的基础上,详细分析了文献[1]和文献[2]中利用密码技术实现层次访问控制的机制,指出了它们的优缺点。更重要的是,提出了一种新的简单而有效的利用密码技术实现层次访问控制的机制,通过与文献[1]和文献[2]中机制的比较,方案在存储和计算复杂度等方面都具有优越性。  相似文献   

9.
在研究和分析传统方差法和最大类间方差法的基础上,提出了一种传统方差法和最大类间方差法相结合的分块处理分割算法。该算法首先求出整个指纹图像的方差,然后计算每一子块的方差。若方差小于整个图像的方差则用方差法对图像进行分割,否则用最大类间方差法进行分割。最后再对图像进行平滑处理。实验结果表明,相对于传统分割方法,该方法无需根据经验选取阈值,能较准确地分割出前景和背景,抗噪能力强,对高对比度和低对比度的图像均具有很好的分割效果。  相似文献   

10.
方差分析法在制导仿真系统VV&A中的应用   总被引:1,自引:0,他引:1  
焦鹏  费惠佳 《计算机仿真》2010,27(6):115-117,166
针对制导仿真系统研究,通过分析和研究方差方法的原理,提出了方差分析法在制导仿真系统VV&A中仿真结果验证和设备误差分析两个重要的应用途径.为了在仿真结果验证时充分利用不同试验条件下的仿真数据和靶试数据,基于方差分析法,对试验条件的不同取值影响仿真结果,并通过对具体试验数据的计算和分析,验证了可行性;对制导仿真系统的误差分析时,提出了设备误差对静态仿真结果影响,丰富了仿真设备误差分析的手段.实践证明,方差分析法是制导仿真系统VV&A中的一种非常有效的辅助手段.  相似文献   

11.
Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.  相似文献   

12.
European Community policy and the market   总被引:1,自引:0,他引:1  
Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.  相似文献   

13.
融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。  相似文献   

14.
Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.  相似文献   

15.
This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.  相似文献   

16.
Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008  相似文献   

17.
Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.  相似文献   

18.
《计算机科学》2007,34(4):148-148
Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.  相似文献   

19.
正The 34th Chinese Control Conference and SICE Annual Conference 2015(CCCSICE2015)is organized by the Technical Committee on Control Theory(TCCT)of Chinese Association of Automation(CAA)and the Society of Instrument and Control Engineers(SICE)of Japan,and locally organized by Hangzhou Dianzi University(HDU).  相似文献   

20.
该文利用DF与CHI统计量相结合的特征选取方法,针对互联网上对外汉语相关领域的网页进行特征提取,并在此基础上,构建了基于标题与正文相结合的两步式主题相关度判定分类器。基于该分类器做对外汉语相关主题的网页爬取工作,实验表明,效率和召回率比传统分类器都有较大程度的提高,目前该分类器已经用于为大型对外汉语语料库构建提供数据源。  相似文献   

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