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通过分析含噪语音信号的特点,引入能够兼顾人耳听觉特性的听觉感知小波变换,构造了新的小波阈值函数,并对小波变换分解后的阈值进行基于微粒群算法的分层优化.仿真实验表明,该方法在不同信噪比条件下均具有较好的去噪性能,语音的可懂度和听觉效果得到有效提高. 相似文献
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In this paper,we construct an orbifold quantum cohomology twisted by a flat gerbe. Then we compute these invariants in the case of a smooth manifold and a discrete torsion on a global quotient orbifold. 相似文献
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The heteroscedasticity is inevitable for the panel data modeling in economics. The two-stage estimation method is a better means to study the heteroscedasticity, in which the basis is to select only one independent variable for samples grouping, it can cause the information used is incomplete. In this paper, we propose to select several variables for grouping using variable selection method, then k-mean algorithm is used to cluster, so the samples classification can be achieved and the heteroscedasticity estimation can be obtained. The results of real example analysis show that the method presented in this paper has obvious advantages in effectiveness and feasibility. 相似文献
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压缩氟硅橡胶O形密封圈蠕变/老化行为研究 总被引:2,自引:0,他引:2
文章通过修正、扩充蠕变动力学模型,形成环境作用下活化粒子产生的物质宏观变化动力学模型,该模型涵盖了原有的蠕变动力学模型,且适用于描述复杂物理化学变化过程.应用该模型分析了压缩氟硅橡胶O形密封圈的蠕变/老化行为,取得很好效果,在常温到200°C的宽广温度范围内,准确描述了压缩氟硅橡胶O形密封圈的老化行为,同时在常温长时间外推验证中表现了良好的稳定性.在描述压缩氟硅橡胶O形密封圈的老化行为过程中,发现了两个新的现象:挥发作用影响压缩氟硅橡胶的蠕变/老化行为;压缩氟硅橡胶O形密封圈的蠕变/老化存在一个特征温度值(84.049°C),温度高于或低于该值时,压缩氟硅橡胶O形密封圈的老化/蠕变将加剧. 相似文献
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Dealing with the missing values is an important object in
the field of data mining. Besides, the properties of compositional data lead to
that traditional imputation methods may get undesirable result if they are directly
used in this type of data. As a result, the management of missing values in
compositional data is of great significant. To solve this problem, this paper
uses the relationship between compositional data and Euclidean data, and proposes
a new method based on Random Forest for missing values in compositional data.
This method has been implemented and evaluated using both simulated and real-world
databases, then the experimental results reveal that the new imputation method
can be widely used in various types of data sets and has good performance than
other methods. 相似文献
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XiaoQin Xiong Yan Jiang ShengAn Xia WuXing Zhang LiXia Yuan ShanTang Liu YunHui Huang 《科学通报(英文版)》2010,55(30):3419-3423
Oxalic-acid-based co-precipitation method was employed to prepare LiNi2/3Mn1/3O2 sample with a high-ordered structure. Li+, Ni2+ and Mn2+ acetates were used as starting materials. The influence of the amount of lithium source in the starting materials on Li+ content, disorder of Li+-Ni2+ ions, and electrochemical performance has been investigated. Rietveld refinement shows that the sample prepared with 20% excess Li-source in the starting materials exhibits a perfect ordered structure. A specific discharge capacity is as high as 172 mAh/g at C/20 in the voltage range of 4.35–2.7 V. However, the cyclability is not satisfactory: about 25.3% fade in capacity was observed over 50 cycles. Chemically stable SiO2 was coated on the surface of LiNi2/3Mn1/3O2 particles. A significant improvement in cyclability was attained with 3 wt% SiO2 coating, which is ascribable to the protection of LiNi2/3Mn1/3O2 particles from being dissolved into the electrolyte. 相似文献
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使用扫描电子显微镜、原子力显微镜和X射线衍射研究了多孔硅薄膜的微结构.SEM图像显示:多孔硅膜表面的微结构比较均匀;沿纵向方向薄膜内部空腔呈流线型分布;孔和孔之间的间距为10~20 nm.AFM形貌表明:其表面在1×1μm范围内的均方根粗糙度为4.75 nm.XRD结果说明:多孔硅薄膜晶体晶格常数随深度增加而变大,多孔硅薄膜孔壁上Si?H键的比例将减少. 相似文献
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采用Ⅱ型参量下转换(SPDC)和后选择技术,实验上制备了保真度达0.831的高纯四光子Greenberger—Home—Zeilinger(GHZ)态.通过理论分析和实验优化,提出一种有效提高四光子对比度的实验方法.同时利用制备的纠缠态,研究了四光子GHZ态的非定域性,得到了对四光子Bell不等式28标准差的偏离,证明制备的态为真正四体纠缠态.本文的研究对实验上获得高对比度的多光子纠缠态及非定域性研究具有非常好的借鉴意义. 相似文献
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