多旋翼无人机执行机构故障重构技术研究

多旋翼无人机应用中一旦发生执行机构故障,将会危及无人机、地面人员与周围环境的安全。研究多旋翼无人机的执行机构故障重构技术有利于对其实施容错控制,提高运行的安全性和可靠性。首先对多旋翼无人机执行机构故障进行分类,建模分析了执行机构卡死和失效两类故障,建立了故障下六旋翼无人机的数学模型,然后分别设计基于自适应观测器的故障重构方法。通过选取合适的自适应律,自动调节非线性观测器的参数,实现对故障信息的精确重构。仿真结果证明了故障重构方法的准确性。     

神经网络在少数投影图像重建中的应用

本文提出了将两种神经网络模型进行套用的图像重建算法。算法将图像重建问题转化为神经网络优化计算,利用Hopfield神经网络（HNN）将各种优化准则转化为模型的能量函数,并应用Adaline网络调整各准则在能量函数中所占的比重,从而求取图像重建的最优解。将其应用于少数投影图像重建,体现出重建精度高、收敛快等特点,取得了令人满意的效果。     

Long transition analysis for digital video sequences

Video indexing is a technique used to extract objects within a video sequence and index them so that they can be used for future retrieval. In many video sequences, special effects such as fade and wipe are incorporated, and in some cases, it is desirable to be able to include objects within such effects for indexing. In this paper, we introduce an automatic process that determines the type of transition and extracts information from it, so that this information can be used in object extraction. Such a process consists of four stages: shot boundary refinement, shot type determination, frame reconstruction for soft transitions, and shot classification for hard transitions. In this paper, we will give the implementation, timing, and performance analysis for each stage. Long transition analysis bridges the gap between shot boundary detection and object tracking and smoothes the process of automatic video indexing for video databases.     

A new method for inpainting of depth maps from time-of-flight sensors based on a modified closing by reconstruction algorithm

Time-of-Flight (ToF) sensors are popular devices that extract 3D information from a scene but result to be susceptible to noise and loss of data creating holes and gaps in the boundaries of the objects. The most common approaches to tackling this problem are supported by color images with good results, however, not all ToF devices produce color information. Mathematical morphology provides operators that can manage the problem of noise in single depth frames. In this paper, a new method for the filtering of single depth maps, when no color image is available, is presented, based on a modification to the morphological closing by reconstruction algorithm. The proposed method eliminates noise, emphasizing a high contour preservation, and it is compared, both qualitative and quantitatively, with other state-of-the-art filters. The proposed method represents an improvement to the closing by reconstruction algorithm that can be applied for filter depth maps of ToF devices.     

一种基于小波和区域的图像拼接方法

图像拼接技术在图像处理中应用非常广泛.本文给出了一种基于区域的图像拼接方法,首先对拼接的图像进行二进小波变换,在小波域中对各个小波分量进行基于区域的图像拼接,最后进行小波重构,得到完整图像.该方法计算量不大,同时二进小波的采用也平滑了图像拼接后可能出现的缝隙.     

Finite-Sized Atom Reconstruction Enhanced High-Frequency Multi-Domain Magnetic Response

The technological advances in wearable electronics and military stealth have spawned extensive research into electromagnetic wave absorbents. Despite the rapid progress in the geometrical modulation of magnetic absorbents, the engineering strategy of microwave-responsive magnetic domains is underdeveloped and the response dynamics remain unclear. Herein, a surface finite-sized atom reconstruction procedure is proposed to accurately modulate the local magnetic topological domains, dramatically enhancing the magnetic loss capacity. Due to the selectivity of atom reconstruction, vortex and stripe domains are controllably hybridized around the porous surface to broaden the interactive domain region, significantly intensifying energy absorption of the microwave field. Meanwhile, the amorphous/crystalline interfaces around atom reconstruction regions can induce interfacial polarization, enabling the optimization of dielectric loss capacity. Therefore, a satisfactory magnetic–dielectric synergy is realized to demonstrate the strong absorption intensity of −31.2 dB and the broad absorption bandwidth of 5.9 GHz. Furthermore, the surface-based magnetic domain transformation and microwave energy attenuation mechanisms are thoroughly revealed to break the black box of structure–function through electron holography and micromagnetic simulation. These achievements demonstrate a promising solution to improve high-frequency magnetic properties and provide a feasible route to interpret the structure-relevant magnetic loss capacity.     

基于线结构光法的三维重建技术的研究

三维重建技术是计算机视觉方面的一个重要的应用。在此首先大体介绍了三维重建技术的发展;然后,介绍了基于线结构光法的三维重建技术;在详细介绍了数学模型的建立、照相机的标定、采集图像的处理、三雏重建方法这四个方面,从而对三维重建技术有了深入的了解。     

相移干涉术中参考波准直误差的数值校正

针对相移干涉术中参考波由于准直误差可能为非倾斜或倾斜球面波的情形,本文提出了一种简单的数字处理方法,不需任何附加测量即可提取真实球面波的几何参数,进而校正由标准波前再现公式所恢复的物波波前误差.本文方法的有效性由模拟试验所证实,并说明了其适用范围.     

基于概率加权平均的Mel子带特征重建算法

本文提出基于概率加权平均的Mel子带特征数据重建算法.该算法选择K个最优重建结果的概率加权平均作为被加性噪声掩蔽的语音特征分量的估计.实验结果表明,基于概率加权平均的语音特征数据重建算法降低了重建误差,减少了帧间突变现象,增强了Mel子带特征的帧间连续性,从而显著提高了语音识别系统对加性噪声的鲁棒性能.     

用查找表和极坐标反投影法实现计算机断层扫描快速重建

为了在普通PC机上实现计算机断层扫描(CT)快速重建,提出了利用查找表和极坐标反投影快速重建方法.该方法首先在极坐标系下利用查找表实现快速反投影,然后将极坐标反投影数据映射到笛卡尔坐标系中,在此过程中,又一次运用查找表技术实现快速插值,有效地节约了时间.计算机仿真结果表明,该方法不但大大提高了重建速度,而且重建质量与传统卷积反投影相当,尤其当重建图像尺寸较小时,可以取代后者.