一种适用于嵌入式媒体播放器的音视频同步方法

目前已存在几种嵌入式媒体播放器,但是由于环境的特殊性,播放时常常会出现音视频不同步的现象。给出了一种适用于嵌入式媒体播放器的音视频同步方法,并在自主开发的以嵌入式Linux和图形用户界面Qt为软件平台的媒体播放器上进行了验证。     

一种基于傅里叶描述子的轴心轨迹自动识别方法

傅里叶描述子是分析和识别物体形状的重要方法之一。文中详细讨论了傅里叶描述子的原理、不变性和实际应用方法;运用人工神经网络分析方法,以傅里叶描述子作为特征向量,对汽轮发电机组轴心轨迹的自动识别进行了探讨;并对3类典型的轴心轨迹的自动识别进行了仿真试验,结果表明该方法是有效、可行的。     

Thermoelectric Properties of Heavy Rare Earth Filled Skutterudites Dy y Fe x Co4?x Sb12

Heavy rare earth element Dy-filled skutterudites (Dy _y Fe _x Co_4?x Sb₁₂) have been synthesized by a melting–quenching–annealing method and sintered by the spark plasma sintering technique. Our results suggest that single-phased Dy _y Fe _x Co_4?x Sb₁₂ compounds could be obtained when the Fe content is less than 1.5. The maximum filling fraction of Dy in skutterudites increases with increasing Fe content. We also found significant lattice expansion induced by Fe substitution at Co sites and Dy filling in the voids. The electrical conductivity, Seebeck coefficient, and thermal conductivity have been measured in the temperature range from 300?K to 800?K. The low-temperature Hall coefficient and carrier mobility are reported in the temperature range from 2.5?K to 300?K. The power factor for Dy _y Fe _x Co_4?x Sb₁₂ increases with increasing Fe content. A significant reduction in lattice thermal conductivity is observed in heavy rare earth element Dy-filled skutterudites due to the low localized vibrational frequency of Dy that effectively scatters low-frequency lattice phonons. The sample with composition Dy_0.41Fe_1.45Co_2.55Sb_12.28 has lattice thermal conductivity as low as 1.05?W?m^?1?K^?1 at room temperature. The thermoelectric figure of merit (ZT) reaches a maximum value of 0.67 at 750?K.     

大气中可吸入粉尘(PM10)β射线法测量的理论与数据处理

本文介绍了应用β射线测量大气中PM10含量的原理及用于β射线探测的G-M计数管的特性;分析了测量数据统计特征及数据处理的理论基础;提出了构成PM10测量系统的方法和相关的数据处理技术。     

微机械双轴电容式加速度传感器设计

设计一款机械噪声较小、灵敏度较高的双轴电容式加速度传感器,其具有4个水平检测单元,X、Y轴向的检测单元各有两组,且水平对称,有效地消除了轴间的交叉干扰;结构中的保护限位装置避免了结构因加速度值过大而断裂失效和结构测量的不准确。该加速度敏感质量块的大小为3 250 μm×3 250 μm×5 μm;栅型条的尺寸大小为1 575 μm×35 μm×5 μm;间距为35 μm,利用Ansys软件对加速度传感器进行性能仿真,得出加速度传感器X和Y轴向的静态灵敏度为0.253 μm/g;电容灵敏度为1.533 pF/g;X和Y轴向的谐振频率为949 Hz,阻尼比为0.83。     

高分辨SAR图像自动区域筛选目标检测算法

在G0分布背景杂波假设下,基于VI-CFAR算法该文提出一种自动区域筛选的恒虚警目标检测算法,以解决高分辨SAR图像复杂环境背景下的目标检测问题。该算法首先利用变化指数(VI)统计量对局部参考窗内的均匀区域进行筛选,以剔除参考窗内具有目标干扰点的非均匀区域;然后利用均值比(MR)统计量对参考窗内同质的均匀区域进行区域合并,以解决杂波边界处的背景杂波筛选问题;最后利用筛选到的同质均匀区域内的像素集合进行背景杂波参数估计,对待检测区域实现二值检测。通过实测SAR图像车辆目标检测实验表明,在多目标和杂波边界复杂环境背景下,该算法具有较稳定的检测性能和虚警抑制能力。     

多级多速率数字滤波在模拟地震振动台试验系统中的应用

本文从模拟地震振动台试验系统的实际应用出发,研究了多级多速率数字滤波在抽样率转换和低通滤波中的作用和设计以及DSP的实现;对其实现过程中的多路开关初始位置的设置、多通道之间时差的处理等问题予以讨论.     

从数字化评价标准看播控设备选型

新一代网络化硬盘播出系统采用了开放式的软硬件平台和标准网络接口协议,在实现全数字、网络化、多频道播出的同时,节约了大量的人力及设备投资。作者根据国家广电总局颁布的《电视中心数字化程度评价办法》（试行）,对硬盘播出系统各功能块进行了详细的评述。     

基于多重分数阶傅里叶变换ISAR快速成像算法

关于机动目标的逆合成孔径雷达成像技术在诸多应用领域扮演着重要的角色,但其应用一直存在一个严重问题——时变多普勒频率,它会在信号回波中引入高阶相位项,如调频率项,如果不对其进行精确补偿,最终获得的ISAR图像质量会出现明显恶化.针对上述问题,大量算法相继被提出用以实现调频率的估计,但是这些算法往往存在运算量大以及传递误差...     

Mechanical Strain‐Tunable Microwave Magnetism in Flexible CuFe2O4 Epitaxial Thin Film for Wearable Sensors

Purely mechanical strain‐tunable microwave magnetism device with lightweight, flexible, and wearable is crucial for passive sensing systems and spintronic devices (noncontact), such as flexible microwave detectors, flexible microwave signal processing devices, and wearable mechanics‐magnetic sensors. Here, a flexible microwave magnetic CuFe₂O₄ (CuFO) epitaxial thin film with tunable ferromagnetic resonance (FMR) spectra is demonstrated by purely mechanical strains, including tensile and compressive strains, on flexible fluorophlogopite (Mica) substrates. Tensile and compressive strains show remarkable tuning effects of up‐regulation and down‐regulation on in‐plane FMR resonance field (H_r), which can be used for flexible tunable resonators and filters. The out‐of‐plane FMR spectra can also be tuned by mechanical bending, including H_r and absorption peak. The change of out‐of‐plane FMR spectra has great potential for flexible mechanics‐magnetic deformation sensors. Furthermore, a superior microwave magnetic stability and mechanical antifatigue character are obtained in the CuFO/Mica thin films. These flexible epitaxial CuFO thin films with tunable microwave magnetism and excellent mechanical durability are promising for the applications in flexible spintronics, microwave detectors, and oscillators.