This paper explores the application of term dependency in information retrieval (IR) and proposes a novel dependency retrieval model. This retrieval model suggests an extension to the existing language modeling (LM) approach to IR by introducing dependency models for both query and document. Relevance between document and query is then evaluated by reference to the Kullback-Leibler divergence between their dependency models. This paper introduces a novel hybrid dependency structure, which allows integration of various forms of dependency within a single framework. A pseudo relevance feedback based method is also introduced for constructing query dependency model. The basic idea is to use query-relevant top-ranking sentences extracted from the top documents at retrieval time as the augmented representation of query, from which the relationships between query terms are identified. A Markov Random Field (MRF) based approach is presented to ensure the relevance of the extracted sentences, which utilizes the association features between query terms within a sentence to evaluate the relevance of each sentence. This dependency retrieval model was compared with other traditional retrieval models. Experiments indicated that it produces significant improvements in retrieval effectiveness.
本文针对移动无线传感网提出一种结合节点移动向量和接收信号强度指示值RSSI(Received Signal Strength Indicator)信息的机会主义路由OR-RSSI,利用Sink节点Beacon报文的RSSI信息建立并更新机会概率值,使用报文广播后所能到达的具有最大机会概率值的最佳节点进行存储转发,完成移动无线传感网信息收集.OR-RSSI是一种良好的后择路由,不以既存路径为基础,不需额外设备支持,具有报文成功传输率高、网络有效吞吐量大以及能耗低等优点.
视频图像中脸像检测是近年来视觉图像检测和模式识别领域的研究热点。提出一种基于实时预测学习分类的脸像快速检测算法,即ARMA-Boost算法。首先根据脸像位置先验信息,利用ARMA模型(auto-regressive and moving average model)预测脸像位置区域,然后采用AdaBoost算法对预测区域进行脸像检测。该方法在时间维度对AdaBoost算法进行扩展,减小脸像搜索范围,提高检测效率。利用该方法对离线视频文件和CCD图像传感器实时脸像视频进行检测,实验结果表明,与支持向量机、传统AdaBoost和基于优化肤色模型的AdaBoost改进算法相比,ARMA-Boost算法脸像检测准确率高,实时性更好,可以对视频脸像进行快速检测应用。
