Robust infrared target tracking using discriminative and generative approaches

The process of designing an efficient tracker for thermal infrared imagery is one of the most challenging tasks in computer vision. Although a lot of advancement has been achieved in RGB videos over the decades, textureless and colorless properties of objects in thermal imagery pose hard constraints in the design of an efficient tracker. Tracking of an object using a single feature or a technique often fails to achieve greater accuracy. Here, we propose an effective method to track an object in infrared imagery based on a combination of discriminative and generative approaches. The discriminative technique makes use of two complementary methods such as kernelized correlation filter with spatial feature and AdaBoost classifier with pixel intesity features to operate in parallel. After obtaining optimized locations through discriminative approaches, the generative technique is applied to determine the best target location using a linear search method. Unlike the baseline algorithms, the proposed method estimates the scale of the target by Lucas-Kanade homography estimation. To evaluate the proposed method, extensive experiments are conducted on 17 challenging infrared image sequences obtained from LTIR dataset and a significant improvement of mean distance precision and mean overlap precision is accomplished as compared with the existing trackers. Further, a quantitative and qualitative assessment of the proposed approach with the state-of-the-art trackers is illustrated to clearly demonstrate an overall increase in performance.     

Concurrent multi-scale design optimization of composite frame structures using the Heaviside penalization of discrete material model

This paper deals with the concurrent multi-scale optimization design of frame structure composed of glass or carbon fiber reinforced polymer laminates. In the composite frame structure, the fiber winding angle at the micro-material scale and the geometrical parameter of components of the frame in the macro-structural scale are introduced as the inde-pendent variables on the two geometrical scales. Considering manufacturing requirements, discrete fiber winding angles are specified for the micro design variable. The improved Heaviside penalization discrete material optimization inter-polation scheme has been applied to achieve the discrete optimization design of the fiber winding angle. An optimiza-tion model based on the minimum structural compliance and the specified fiber material volume constraint has been estab-lished. The sensitivity information about the two geometrical scales design variables are also deduced considering the char-acteristics of discrete fiber winding angles. The optimization results of the fiber winding angle or the macro structural topology on the two single geometrical scales, together with the concurrent two-scale optimization, is separately studied and compared in the paper. Numerical examples in the paper show that the concurrent multi-scale optimization can fur-ther explore the coupling effect between the macro-structure and micro-material of the composite to achieve an ultra-light design of the composite frame structure. The novel two geometrical scales optimization model provides a new oppor-tunity for the design of composite structure in aerospace and other industries.     

基于谱元法的空间刚架动力学特性分析

以空间刚架结构为研究对象,应用谱元法研究其动力学特性,依次推导出杆、轴和铁木辛柯梁的动力学刚度阵,进而得到空间刚架的动力学刚度阵和频域响应的理论方程,拓展了谱元法应用范围。编程计算获得空间刚架的固有频率和点的谐响应曲线,与有限元分析相比较,进一步得到载荷下的瞬态响应。研究表明,谱元法在刚架结构的动力学特性分析中,比有限元方法高效高精度,更适宜解决中高频振动问题。     

面向内容的立体视频帧重要性区分模型研究

异构网络引起的视频传输失真是影响视频终端感知质量的重要因素,通常只能在解码端进行评估和补偿。因此在编码端建立一个面向内容的立体视频传输失真模型,考虑错误隐藏和错误扩散两种失真,通过近似估计视频中各帧对终端质量的贡献度,从而实现每帧重要性的区分。新模型综合考虑了视频帧编码位置以及表征内容的编码模式、运动矢量、视差矢量等关键信息,可以作为视频在异构网络中传输策略的重要依据。     

基于共轭梯度法的感知矩阵优化方法

压缩感知理论中降低信号维数的关键问题是构造有效的测量矩阵。在已知稀疏基的情况下,基于ETF（Equiangular Tight Frame）框架的测量矩阵构造方法和稀疏信号重构过程均依赖于感知矩阵。为此,设计了一种基于共轭梯度法的感知矩阵优化方法,该方法简单易行,且所求结果的Gram矩阵与目标Gram矩阵更接近。 实验结果表明,此感知矩阵优化方法在理论分析、实际图像应用及算法有效性上均具优势。     

基于改进粒子群的薄壁变截面刚架临界载荷优化算法

针对大型变截面薄壁结构的稳定问题,以一类任意约束对称结构受非对称载荷的单跨刚架为研究对象,结构拆分为相关铁木辛柯（Timoshenko）梁,结合差分原理和最优化方法,以每段刚架的每个离散点挠度、临界载荷、轴力、剪力和梁端弯矩为设计变量,建立求解满足边界条件的非线性差分方程模型,提出基于优胜劣汰粒子更新的粒子群（IPSO）临界载荷优化算法。运用JAVA编程语言编制对应优化程序,分析典型算例并核实ABAQUS仿真结果。研究表明,本文提出的优化算法获得了有效的变形位型和高精度的临界载荷计算,能更好地描述刚架受力下位型和载荷的力学关系,进一步为工程设计与分析提供支持。     

基于波动法的框式结构功率流主动控制方法与实验研究

为了研究扰动影响下框式结构中的功率流传播与主动控制,首先采用波动方法建立了框式结构的动力学模型并获得了其在扰动下的精确动力学响应,进一步得到结构中传播的功率流,并以此为目标函数,优化得到了最优控制力的大小与相位,然后对结构施加最优控制力,实现了框式结构的功率流主动控制。对框式结构功率流主动控制方法进行了数值计算分析与实验验证。结果表明：采用波动方法计算框式结构的动力学响应精确可靠;通过数值计算与实验研究可知功率流主动控制可以明显降低框式结构全频域内的抖动,验证了基于波动方法功率流主动控制的正确性与有效性。     

准噶尔盆地南缘四棵树凹陷构造变形特征分析

鉴于准噶尔盆地南缘地区已经成为新疆石油勘探的重要靶区,但由于其勘探程度低,四棵树凹陷的构造研究不够深入,无法进行彻底的油区构造分析,对进一步寻找油气圈闭造成了困难.文中对四棵树凹陷地质构造特征进行了详细的分析,将其分为五大构造体系:(1)四固南断裂构造体系;(2)四棵树—–西湖—–奎屯南背斜;(3)固尔图断裂构造体系;(4)艾卡西断裂构造体系;(5)卡因迪克断裂构造体系;然后分别对每个构造体系进行逐一解剖,即主要从地震剖面入手,一一进行地震地质剖面解释,将其划分为每个具体构造,讨论其形成的时期以及动力学特点.重点是建立四棵树凹陷的构造格架,为进一步四棵树凹陷的油气勘探提供了有力的证据.     

Conformal invariance for nonholonomic system of Chetaev’s type with variable mass

Conformal invariance and conserved quantities for a nonholonomic system of Chetaev’s type with variable mass are studied. The conformal factor expressions are derived. The necessary and sufficient conditions are obtained to make the system’s conformal invariance Lie symmetrical. The conformal invariance of the weak and strong Lie symmetries for the system is given. The corresponding conserved quantities of the system are derived. Finally, an application of the result is shown with an example.     

基于惯性参考系基准的快速传递对准方法

研究了以惯性参考系为基准的新型传递对准方法。推导了计算惯性坐标系和计算体坐标系传递对准动态误差模型,并给出了相应的"速度+姿态"观测方程。基于惯性参考系的对准方法通过链式法则将子惯导输出的姿态矩阵描述为三个变换矩阵之积,其中两个变换矩阵通过对准时间和主惯导提供的位置信息可得到精确求解,剩余的变换矩阵(子惯导体坐标系至惯性坐标系间的变换矩阵)通过子惯导陀螺仪的输出进行解算,其误差通过传递对准估计得到的失准角进行补偿。对提出的两种对准方法进行摇摆实验验证,方位对准误差优于4’(1)。与传统基于导航坐标系的方法相比,基于惯性坐标系的方法直接将误差定位到惯性坐标系上,具有算法简便的特点。