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1.
数据库中发现知识的方法   总被引:5,自引:0,他引:5  
本文介绍了从数据库中发现知识的含义,讨论了KDD中发现知识的基本方法。  相似文献   

2.
NetDDE使用问答清华大学自动化系(100084)靳开岩问题:NetDDE要占用系统资源吗?解答:在我们测试系统性能时发现,NetDDE需要占用Windows系统GDI资源,而且占用较多,我们在软件中采用了11条NetDDE连接,共占用了5%的GD...  相似文献   

3.
信息提取的能力与效率已成为限制遥感应用发展的瓶颈问题。数据开采(DM)与知识发现(KDD)概念的提出及其理论体系的建立为解决这一问题提供了一种全新的视角。基于对DM和KDD的过程分析和对卫星遥感数据的信息论理解,提出了针对地质应用的卫星遥感数据开采与知识发现的技术框架。以此为主线,把时相选择考虑为知识发展过程的一个特定步骤;在研究地质遥感信息的时间效应基础上,探讨了目标知识发现的“微差信息处理”方法和信息融合技术,应用实例证明该框架的合理性及其相应方法的实际意义。  相似文献   

4.
经验公式发现系统FDD   总被引:9,自引:0,他引:9  
从大量实验数据中发现经验公式是对传统的数据拟合技术的革新,本文介绍作者研制的经验公式发现系统FDD。它是将人工智能技术与数据拟合技术结合起来,通过启发式搜索,找到满足精度要求经验公式,FDD系统比国外BACON系统,在公式表示上扩充为函数型公式。  相似文献   

5.
本文根据我们在[1]中提出的基于超媒体的开放知识发现系统模型HyperKDD的基础上讨论HyperDis的体和纱结构。  相似文献   

6.
事件序列中的知识发现研究   总被引:3,自引:1,他引:2  
事件的序列是数据的一种常见形式,其中的知识发现问题是近年来KDD的一个活跃的研究领域。本文首先给出了事件序列中知识发现问题的形式描述和框架算法,然后讨论了数据库中发现大序列的问题,具体描述了发现数据库中大序列的算法。  相似文献   

7.
基于集合理论的KDD方法   总被引:3,自引:1,他引:2  
本文运用集合理论对KDD进行了描述,介绍了基于集合理论从数据库中发现分类规则的方法,并给出了实现算法和一个应用实例  相似文献   

8.
基于Internet的课件信息发现和收集Agent的研究   总被引:9,自引:0,他引:9  
文中介绍一个基于nternet的信息检索系统:DOLTRI-Agent.DOITRI-Agent用于从Internet上发现和收集用于远程武术和教学。  相似文献   

9.
本文针对KDD分类规则的发现与学习,提出了最小化分类规则和最大化分类规则的概念,并给出了对分类规则进行最小化和最大化的算法。  相似文献   

10.
报道了三嗪类化合物与豌豆 D1 蛋白结合的分子模拟研究。结果表明, 三嗪类化合物主要以氢键方式与 D1 蛋白结合, 同时亦发现, S E R268 或 H I S215 是这类化合物与 D1 蛋白作用时重要的结合位点  相似文献   

11.
The concept of ‘the field’ is significant in ethnographic research as well as qualitative research methods more generally. However, how a field researcher enters the field is usually taken for granted after gaining access to the field. We suggest that entrance is a distinct phase of fieldwork that differs from negotiating access. Entrance is not a trivial event; rather, it is a rite of passage into a complex practice world and marks a critical field moment. Drawing on our ethnography and insights from hermeneutics and anthropology, we show that a practical understanding of the field represents a fusion of horizons where a fieldworker is thrown. The concept of thrownness highlights the fact that the fieldworkers' own historicity and prejudices affect their entrance into the field; hence, entrance into the field orientates an ethnographer in the field and influences the entire period of fieldwork that follows. Our theorizing is intended as a contribution towards advancing the discussion of qualitative research methods.  相似文献   

12.
以东北师范大学昆虫学野外实习为例,从实习地点和时间、实习准备、实习内容及实习指导等方面总结昆虫学野外教学实习 的改革与实践经验,并结合近年来实习结果对野外实习主要选题进行分析,旨在为进一步改进和提高昆虫学野外教学实习的效果 提供参考。  相似文献   

13.
Optical fibre-based evanescent field sensors are proving to be viable and useful in the detection of chemicals, toxins, gases and other species. Such fibre sensors rely on weak interactions between the surrounding environment and the external “evanescent” field associated with bound modes of electromagnetic radiation propagating through an optical fibre. Of fundamental importance in the design of such sensors is the fraction of the total guided field power that propagates as the evanescent field. By increasing this relative evanescent field power, sensor gain can be improved. As the evanescent field is determined by the refractive index profile (RIP) of the sensor and the surrounding environment, design of the sensor RIP is critical. This paper presents a rigorous approach to this RIP design problem, formulated in terms of an optimization problem with the normalized evanescent field power as the payoff, RIP as the input, and a simple electric field model as the constraint. An RIP design procedure utilizing dynamic programming is then presented, along with an example that illustrates the improvement obtainable over existing designs.  相似文献   

14.
通过隐函数拟合实现曲面重建是计算机图形学领域中一项重要而有挑战性的工作.受经典物理学中极性场模型及扩展点集思想的启发,提出一种称为"场拟合"的隐曲面重建方法.该方法将三维曲面表达为极性场的零等值面,极性场由许多粒子对产生,则曲面重建过程就转化为求粒子分布的过程,使用一种贪婪算法求解粒子的分布.实验结果表明,采用文中的场拟合方法的重建结果优于已有的隐曲面重建方法.  相似文献   

15.
为了把广泛应用于网格四边形化和纹理合成的二维表面标架场拓展到三维,提出一种生成三维对称标架场的方法.不同于表面对称标架场(四对称方向场),二维标架场的对称性能用一个切平面的旋转角度来表示,而三维对称标架场的对称性却不能这样简单地表示.为了解决这个问题,利用球面函数来获得一个对称性表述,该表述对于绕任意一个轴的π/2旋转以及它们的复合是不变的.基于球面函数的表示可以获得一个有效的标架场光顺程度的度量,并以球面调和分析进行加速计算;基于一组边界约束,可以通过极小化这个度量函数来获得一个光顺的标架场,该标架场在表面上能很好地对齐法线.最后通过表面投影、流线追踪和奇异点来可视化这个标架场,并将这个光顺的标架场用于六面体网格生成,且讨论了它在生成高质量纯六面体网格方面的潜力,其与表面标架场在生成四边形网格方面的潜力是一致的.  相似文献   

16.
17.
In the future International Linear Collider (ILC) experiment, high performance tracking is essential to its physics program including precision Higgs studies. One of major challenges for a detector such as the proposed International Large Detector (ILD) is to provide excellent momentum resolution in a magnetic field with small (but non-negligible) non-uniformity. The non-uniform magnetic field implies deviation from a helical track and hence requires the extension of a helical track model used for track fitting in a uniform magnetic field. In this paper, a segment-wise helical track model is introduced as such an extension. The segment-wise helical track model approximates the magnetic field between two nearby measurement sites to be uniform and steps between the two sites along a helix. The helix frame is then transformed according to the new magnetic field direction for the next step, so as to take into account the non-uniformity of the magnetic field. Details of the algorithm and mathematical aspects of the segment-wise helical track model in a Kalman-filter-based track fitting in the non-uniform magnetic field are elaborated. The new track model is implemented and successfully tested in the framework of the Kalman filter tracking software package, KalTest, which was originally developed for tracking in a uniform magnetic field.  相似文献   

18.
针对航空交错延时积分(Time delay and integration, TDI)红外影像奇数行和偶数行之间灰度差异、错动以及影像降晰问题, 提出了一种交错TDI红外影像复原方法. 首先采用对影像灰度差异不敏感的基于相位相关 (Phase-only correlation, POC) 的位移估计方法估计奇数行影像和偶数行影像之间的亚像素精度位移场. 其次以奇数行影像为参考, 根据位移估计结果对偶数行影像做点对点灰度校正, 并对齐奇数行影像和灰度校正后的偶数行影像. 最后采用BTV (Bilateral total variation)正则化超分辨率重建方法反降晰, 得到复原影像. 实验结果表明复原影像中奇偶行的错动得到有效补偿, 地物的边缘和纹理结构更加清晰, 影像质量显著提高.  相似文献   

19.
The electromagnetic field commutation relations are defined in terms of geometric factors that are double averages over two finite four-dimensional space-time regions. The square root of any of the uncertainty relations derived from the aforementioned commutators is taken as a critical field, in the sense that any electromagnetic field much larger than it can be treated as classical. Another critical electromagnetic field associated with the quantum information control of vacuum fluctuations can be chosen as the square root of the mean quadratic fluctuation of each quantity of electromagnetic field, when the number of photons is defined and is equal to zero. Any electromagnetic field expectation value could be measured if it is much greater than the last critical field. This article covers a magnitude order comparison between the critical fields and its consequences for measuring the electromagnetic field information. Presented at the 38th Symposium on Mathematical Physics “Quantum Entanglement & Geometry”, Toruń, June 4-7, 2006.  相似文献   

20.
This paper uses the literature of educational technology as the site of analysis in order to map the field of educational technology. Having considered Kuhn and Bourdieu's theories, the paper frames the analysis of the field in Bernsteinian terms as a horizontal knowledge structure in a vertical knowledge discourse. Using the concepts of interacting discursive planes, the paper maps the field in terms of its general approach planes and its problem planes. Finally, the paper shows that researchers in the field themselves acknowledge its weak grammar, and calls for commensurability of approaches to be acknowledged in order for robust knowledge to be developed and the legitimacy of the field to be enhanced.  相似文献   

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