Fast exact maximum likelihood estimation for mixture of language model     

Yi Zhang  Wei Xu 《Information processing & management》2008

Language modeling is an effective and theoretically attractive probabilistic framework for text information retrieval. The basic idea of this approach is to estimate a language model of a given document (or document set), and then do retrieval or classification based on this model. A common language modeling approach assumes the data D is generated from a mixture of several language models. The core problem is to find the maximum likelihood estimation of one language model mixture, given the fixed mixture weights and the other language model mixture. The EM algorithm is usually used to find the solution.  相似文献   

Teacher-directed learning in view-independent face recognition with mixture of experts using single-view eigenspaces   总被引：1，自引：0，他引：1  

Reza Ebrahimpour  Ehsanollah Kabir 《Journal of The Franklin Institute》2008,345(2):87-101

We propose a new model for view-independent face recognition by multiview approach. We use the so-called “mixture of experts”, ME, in which, the problem space is divided into several subspaces for the experts, and the outputs of experts are combined by a gating network. In our model, instead of leaving the ME to partition the face space automatically, the ME is directed to adapt to a particular partitioning corresponding to predetermined views. To force an expert towards a specific view of face, in the representation layer, we provide each expert with its own eigenspace computed from the faces in the corresponding view. Furthermore, we use teacher-directed learning, TDL, in a way that according to the pose of the input training sample, only the weights of the corresponding expert are updated. The experimental results support our claim that directing the experts to a predetermined partitioning of face space improves the performance of the conventional ME for view-independent face recognition. In particular, for 1200 images of unseen intermediate views of faces from 20 subjects, the ME with single-view eigenspaces yields the average recognition rate of 80.51% in 10 trials, which is noticeably increased to 90.29% by applying the TDL method.  相似文献   

洞庭湖区湖洲资源生态开发模式的初步研究──以沅江市为例     

贺建林  李永平  周文奇 《湘潭师范学院学报(社会科学版)》1997,(6)

初步研究了洞庭湖区湖洲资源的生态开发模式和生态开发中尚存在的问题,并在此基础上提出了开发对策．  相似文献   

一元强酸与弱酸的分步滴定     

金建华  俞青芬 《青海师专学报》2005,25(6):41-42

本文从一元强酸与弱酸滴定的误差公式判断用强酸进行分步滴定的可能性．  相似文献   

海岛生态农业建设初探——以岱山岛为例     

鲍燕芬 《资源科学》1993,15(3):33-39

发展农业经济必须和农业生态环境相结合的今天，生态农业是农业发展的必然趋势。我国众多的岛屿，特别是丘陵岛屿，绝大多数都面临着一系列相近的环境问题：耕地缺乏、水源不足、能源紧张、资源衰退。但海岛也有其优点：渔盐资源丰富，风能、太阳能、海洋能开发潜力大，气候资源优越。本文以舟山群岛的岱山岛为例，虽海岛生态农业的建设作了初步探讨，认为应充分利用海岛的优势，因地制宜，走农、林、牧、副、渔全面发展的道路。最后本文还提出了几种有海岛特色的生态农业模式，希望能为我国诸多海岛的农业发展提供借鉴  相似文献   

混合随机变量的分布     

魏瑛源 《河西学院学报》2008,24(2)

保险领域中,用来模拟保险理赔支付的分布函数有连续增长的部分,同时也有可数个离散的、正的跳跃部分.这种情况下,描述这种风险的分布函数是离散和连续分布的混合分布.本文讨论混合随机变量的分布函数与数字特征.  相似文献   

4级m序列发生器数学模型的仿真分析     

陈军 《温州大学学报(社会科学版)》2014,(4):43-47

对m 序列的数学模型进行了研究,探讨了实现m 序列的生成过程,设计了4 级移位寄存器的仿真模型,并运用SystemView 软件对其进行了仿真分析.结果表明,所设计的仿真模型的电路是合理的,结果与理论分析相符.  相似文献   

新闻传播教育的若干核心问题--对国外20所新闻传播院系的调研报告   总被引：4，自引：0，他引：4  

钟新  周树华 《国际新闻界》2006,(4):5-11

本文是对国外20所新闻传播院系的院长、系主任和教授的系列深度访谈的归纳和总结。探讨主题包括新闻传播的社会功能与新闻传播教育的使命、本科硕士博士三个层次教育的培养目标与培养模式、师资结构及其评价体系。基本结论为:新闻传播教育的最终使命是培养有社会责任感的新闻传播工作者,而学生培养模式和师资结构当适应培养目标。  相似文献   

A conceptual model of feedback mechanisms in adjusted affordances – Insights from usage of a mental mobile health application     

《International Journal of Information Management》2023

  相似文献