基于MLER和GMM的语音音乐分类

研究了音频信息处理中一项重要的预处理工作:语音音乐分类。针对语音信号处理中遇到的实际问题,选择合适的音频特征和分类器来对音频数据进行语音和音乐分类。采用二级系统,选择优化低能量率(ModifiedLow Energy Ratio,MLER)以及梅尔频谱倒谱系数(Mel Frequency Cepstral Coefficients,MFCC)作为音频特征,通过贝叶斯分类和混合高斯分类器进行分类。最后,使用上下文分类器对分类结果进行修正。实验结果表明,这种分类方法准确率和速度都较好。

基于MLER的语音/音乐分类方法

音频分类是音频信号处理中一项重要的预处理工作。该文描述了一种基于能量的分类方法,将音频信号分为语音和音乐2种类型。分类的过程分为3个阶段,首先计算优化低能量率MLER(modified low energy ratio)作为特征,然后利用初级分类器得到初步分类的结果,最后利用音频类别的前后相关性,使用上下文分类器修正初始分类得到最终分类的结果。该文重点对MLER中参数的合理选取范围进行了讨论,并对传统的初始分类器作了改进,用非参数分类器和参数分类器代替原有的Bayes硬判决的方法,避免了由于门限选择不当所带来的分类错误。实验表明,使用参数分类器时,对纯语音和纯音乐分类效果很好,正确率达99%以上。

基于非结构化四边形网格的VOF法

提出了一种基于非结构化四边形网格的VOF法,用以模拟二维自由表面流动问题。由于非结构化四边形网格在拟合任意复杂曲线边界上的优势,此法能够在不进行任何边界处理和不引入任何人工糙度的情况下直接、准确地求解具有任意边界形状的界面对流问题。此法采用PLIC法来重构界面,以保证界面具有二阶空间精度;采用MLER法来对流流体体积,以提高算法的体积守恒性。此外,为了提高算法的计算效率,文中针对非结构化四边形网格提出了一种确定界面截距的解析方法。大应变界面对流数值实验表明:此法具有较高的体积守恒精度和二阶的形状误差收敛率。

适用于具有复杂海底边界的自由表面流动模拟方法

提出了一种适用于具有复杂海底边界的自由表面流动模拟算法?基于非结构化四边形网格的VOF法。利用非结构化四边形网格在拟合曲线边界上的优势,此法能够在不引入任何边界处理和人工耗散的条件下,直接求解具有任意复杂海底边界的自由表面流动问题。该算法采用MLER法来对流界面,提高了VOF算法的体积守恒精度。大应变界面对流数值实验结果表明,该算法体积守恒性较好,且具有二阶的形状误差收敛率。

A Novel VOF-Type Volume-Tracking Method for Free-Surface Flows Based on Unstructured Triangular Mesh

A novel VOF-type volume-tracking method for two-dimensional free-surface flows based on the unstructured triangular mesh is presented. Owing to the inherent merit of the unstructured triangular mesh in fitting curved boundaries, this method can handle the free-surface problems with complex geometries accurately and directly, without introducing any complicated boundary treatment or artificial diffusion. The method solves the volume transport equation geometrically through the Modified Lagrangian-Eulerian Re-map （MLER） method, which is applied to advective fluid volumes. Moreover, the PLIC method is adopted to give a second-order reconstructed interface approximation. To validate this method, two advection tests were performed for the establishment of the accuracy and convergence rate of the solutions. Numerical results for these complex tests provide convincing evidence for the excellent solution quality and fidelity of the method.

Application of the VOF method based on unstructured quadrilateral mesh

To simulate two-dimensional free-surface flows with complex boundaries directly and accurately, a novel VOF (Volume-of-fluid) method based on unstructured quadrilateral mesh is presented. Without introducing any complicated boundary treatment or artificial diffusion, this method treated curved boundaries directly by utilizing the inherent merit of unstructured mesh in fitting curves. The PLIC (Piecewise Linear Interface Calculation) method was adopted to obtain a second-order accurate linearized reconstruction approximation and the MLER (Modified Lagrangian-Eulerian Re-map) method was introduced to advect fluid volumes on unstructured mesh. Moreover, an analytical relation for the interface’s line constant vs. the volume clipped by the interface was developed so as to improve the method’s efficiency. To validate this method, a comprehensive series of large straining advection tests were performed. Numerical results provide convincing evidences for the method’s high volume conservative accuracy and second-order shape error convergence rate. Also, a dramatic improvement on computational accuracy over its unstructured triangular mesh counterpart is checked.

一种快速稳健的语音/音乐分类方法

介绍了一种简单而有效的区分语音/音乐的方法。该方法仅提取唯一的区别性特征,即改进型低能量帧率(MLER),应用贝叶斯最大后验分类器判断每1段的音频类别,再根据音频流的相邻段有很强的相关性这一特点,采用一种新颖的基于相关性的后验决策方法对分类器的分类结果进行进一步改善。实验结果表明,该方法算法简单,分类效果好。

3种非线性波浪载荷计算方法介绍及其实船应用比较

介绍3种预报非线性波浪载荷的时域方法,分别是规则波法、等效韦布尔法和极大波法。以第二代40万吨超大型矿砂船为例,分别使用此3种方法对中垂和中拱波浪弯矩做了预报,得到3种方法下的不同波浪弯矩值,并比较3种方法的优缺点。此3种方法,在实际工程中都可被船级社接受使用,但从目标船的计算结果看,最终的弯矩值有10%左右的差距。所以非线性波浪弯矩的计算结果,会根据计算方法的不同而有所不同,实际工程项目中可以根据需要合理选择计算方法。