吊车钢丝绳非线性谐振建模及消谐控制

对于欠驱动吊车而言, 已有的方法都只考虑如何消除摆角. 然而当钢丝绳的摆角很小时, 钢丝绳上可能仍 然会存在严重的谐振. 针对吊车的消谐问题, 本文率先提出了一种基于钢丝绳–电机轴的非线性谐振力矩模型. 具体而言, 先利用振动力学的方法, 建立了非线性谐振力矩模型, 该模型可以将钢丝绳上的非线性谐振力矩归算到电机轴上, 然后通过电机控制器调节电机的输出力矩, 使得电机输出的基波主力矩上叠加一个大小相等方向相反的非线 性谐振力矩, 以达到消除钢丝绳上的谐振力矩的目的. 最后通过Simulink仿真和实验证明该方法具有良好的控制性 能, 不仅可以有效消除钢丝绳上的谐振, 并且能进一步减小摆角.     

运动人体阴影检测算法

为了抑制运动人体检测与跟踪中运动人体阴影的影响,提出了一种基于光照模型和图像纹理特征的阴影检测算法.首先依据光照模型理论,将互相关函数引入算法,并根据背景图像和当前图像对应像素点的互相关函数值判断其是否为阴影点.在此基础上,依据图像的纹理特征,将交叉熵函数引入算法,对互相关函数判断为非阴影点的像素,进行二次判断.该算法利用泰勒级数将交叉熵函数中的对数和除法运算转化为乘法运算,简化了运算过程.通过白天和晚上两种条件下的实验,验证了算法的准确性和有效性.     

基于文件拆分与高斯消去的线性方程组求解

针对集群系统内存不足导致大规模矩阵无法调入的情况,设计并实现一种基于文件拆分与高斯消去的线性方程组求解算法,将大规模系数矩阵文件连续拆分为多个规模可控的子文件进行存储和计算,使服务器空闲内存小且具有较好的计算能力。在ABEEMσπ模型中的应用结果表明,当Altix3700服务器任务提交量大、CPU占有率高时,该算法仍可以计算出蛋白质分子的电荷分布。     

融合颜色相关性和纹理差异的阴影检测方法

在雨天交通视频中,车辆同时受阴影和水汽拖尾的干扰。为此,在分析目标车辆、路面、阴影和水汽拖尾区域特性的基础上,提出一种融合颜色相关性和纹理差异的阴影检测方法。由当前点与背景点的HIS向量点积测量颜色相关程度,检测出车辆目标和水汽拖尾区域,利用当前区域和背景区域的纹理差异区分深色车辆和阴影。实验结果表明,该方法能较好地检测雨天交通视频中运动车辆的投射阴影,且能有效去除水汽拖尾,从而保证车辆的正确分割。     

基于多线程的音频设备上位机控制系统

设计一种音频设备的上位机控制系统,实现对多台音频设备的集中和远程控制。为了保证上位机在与设备通信的同时,能及时响应前台界面的用户操作,引入了多线程技术。同时,音频设备具有经常被持续、快速调节同一参数的特点,为解决在此情况下由于硬件通信速度有限而导致的设备滞后响应上位机用户操作的问题,设计了一种冗余命令剔除机制。该机制不仅有效地减少了通信占用的资源,而且更好地保证了用户对设备调节控制的实时性。     

端到端冗余流量消除技术的指纹选择算法研究

为了兼顾服务器端的内存消耗和有效性,在分析了现有端到端冗余流量消除技术中的指纹选择算法后,提出了贪婪指纹选择算法。该算法认为两个数据包中相同片段的邻接片段很有可能也是相同的,基于这一原理,邻接片段的指纹也将被选为代表指纹,有效地避免了在服务器端缓存整个数据包,大大减少了服务器端的内存消耗。仿真实验结果表明,该算法与现有的指纹选择算法相比,能够大大减少服务器端和用户终端的内存消耗,同时冗余消除率在10%-50%之间,与现有算法相近,证明了该算法的有效性。     

Negation-Limited Complexity of Parity and Inverters

In negation-limited complexity, one considers circuits with a limited number of NOT gates, being motivated by the gap in our understanding of monotone versus general circuit complexity, and hoping to better understand the power of NOT gates. We give improved lower bounds for the size (the number of AND/OR/NOT) of negation-limited circuits computing Parity and for the size of negation-limited inverters. An inverter is a circuit with inputs x ₁,…,x _n and outputs ¬ x ₁,…,¬ x _n . We show that: (a) for n=2 ^r ?1, circuits computing Parity with r?1 NOT gates have size at least 6n?log?₂(n+1)?O(1), and (b) for n=2 ^r ?1, inverters with r NOT gates have size at least 8n?log?₂(n+1)?O(1). We derive our bounds above by considering the minimum size of a circuit with at most r NOT gates that computes Parity for sorted inputs x ₁≥???≥x _n . For an arbitrary r, we completely determine the minimum size. It is 2n?r?2 for odd n and 2n?r?1 for even n for ?log?₂(n+1)??1≤r≤n/2, and it is ?3n/2??1 for r≥n/2. We also determine the minimum size of an inverter for sorted inputs with at most r NOT gates. It is 4n?3r for ?log?₂(n+1)?≤r≤n. In particular, the negation-limited inverter for sorted inputs due to Fischer, which is a core component in all the known constructions of negation-limited inverters, is shown to have the minimum possible size. Our fairly simple lower bound proofs use gate elimination arguments in a somewhat novel way.     

Parametric polynomial spectral factorization using the sum of roots and its application to a control design problem

This paper presents an algebraic approach to polynomial spectral factorization, an important mathematical tool in signal processing and control. The approach exploits an intriguing relationship between the theory of Gröbner bases and polynomial spectral factorization which can be observed through the sum of roots, and allows us to perform polynomial spectral factorization in the presence of real parameters. It is discussed that parametric polynomial spectral factorization enables us to express quantities such as the optimal cost in terms of parameters and the sum of roots. Furthermore an optimization method over parameters is suggested that makes use of the results from parametric polynomial spectral factorization and also employs two quantifier elimination techniques. This proposed approach is demonstrated in a numerical example of a particular control problem.     

An Optimizing Compiler for Parallel Chemistry Simulations

Well designed domain specific languages have three important benefits: (1) the easy expression of problems, (2) the application of domain specific optimizations (including parallelization), and (3) dramatic improvements in productivity for their users. In this paper we describe a compiler and parallel runtime system for modeling the complex kinetics of rubber vulcanization and olefin polymerization that achieves all of these goals. The compiler allows the development of a system of ordinary differential equations describing a complex vulcanization reaction or single-site olefin polymerization reaction—a task that used to require months—to be done in hours. A specialized common sub-expression elimination and other algebraic optimizations sufficiently simplify the complex machine generated code to allow it to be compiled—eliminating all but 8.0% of the operations in our largest program and enabling over 60 times faster execution on our largest benchmark codes. The parallel runtime and dynamic load balancing scheme enables fast simulations of the model.     

基于视频虚拟检测带的交通流量检测方法

交通数据的正确掌握对后续的交通控制起着至关重要的作用,采用基于视频虚拟检测带的交通流量检测方法,对检测带范围内像素点RGB的强度值进行统计,将无车辆时的统计值作为标准特征模板并执行模板更新策略,通过计算每一帧实时视频图像的特征值与标准模板特征值的距离进行车辆检测.为了提高检测精度,提出了一种基于阴影特征的阴影检测算法.在早晨和中午的不同光照条件下进行试验,在阴影明显的情况下,该方法的检测准确率在91％以上,在阴影不明显的情况下,检测准确率达到95％,可满足智能交通的需要.