基于提高背景区域调制度的无效点云剔除方法

在条纹投影三维测量技术中,相机获取的图片中会存在背景和阴影区域,这两部分区域不包含物体表面形貌的相关信息,最终转换的三维点云是无效的,必须对无效点云识别并剔除。本文从提高背景区域的调制度角度出发,提出了一种新的无效点云剔除方法。通过实验证明了该方法的可行性和有效性。

复变函数在确定开采沉陷有效预计点中的应用

基于矢量格式向栅格格式转换的基本原理,构造一复变函数,推导给出了确定有效区域范围内的预计点的判别方法,结合C++的运算符重载技术,构造了有效区域外无效计算点的剔除模型,解决了应用PC机进行海量数据计算中速度慢、内存小的技术难题,是应用概率积分法进行大范围全盆地地表移动变形快速计算的有效途径之一。研究区域为2.5km2,利用剔除无效点模块所需时间为17.4h,不利用该模块所需时间为28.5h,速度提高了38.9%。该方法具有计算速度较快的特点,方便工程应用。

最短时间航线自动生成的改进方法

针对已有的最短时间航线自动生成算法存在搜索效率较低、航线准确度较低的不足,提出了基于瞬时水深模型的最短时间航线自动生成改进算法。利用无效点定义和动态包络矩形的策略,优化最短时间航线生成;采用高精度的瞬时水深模型提高最短时间航线自动生成的准确度。实验结果表明:此方法与已有的方法相比,在自动生成航线的质量和效率上都有明显的提高。

基于彩色图像轮廓的深度图像修复方法

针对飞行时间相机获取的深度图像存在大量无效点的问题,提出了一种基于彩色图像轮廓的深度图像修复方法。该方法先通过无效点邻域内像素的值和高斯函数来确定该邻域的方差,结合无效点邻域内有效点个数和方差计算所有无效点的填充顺序,完成填充过程的优先级评估;再将彩色图像中目标物体轮廓投射到深度图像中,结合投影轮廓和欧式距离函数实现对无效点的填充。实验结果表明,与其他常用的修复算法相比,本文算法可以在保护目标物体边缘的前提下,实现对无效点的有效填充,针对不同目标物体,信噪比指标提高了2~14 dB。

高效计算因果网中的干预

在因果网中,对和积问题因果效果的计算是其首要问题,从有向无环图的角度,研究者们发现每一个因果网都有一个与之对应的贝叶斯网络,干预是因果网的一个基本操作。类似于贝叶斯网络中的剪枝策略,在剪枝掉所有无效结点后,文中设计了一种优化的算法OFDo来计算对因果网中每个结点的完全原子干预。文中接着研究多干预操作,发现多干预操作具有可交换性,并基于多干预操作的可交换性证明了多干预操作的优化计算策略。最后,通过实验证实OFDo计算对因果网中所有结点完全原子干预的效率比目前的算法都好。

CoMP-transmission-based energy-efficient scheme selection algorithm for LTE-A systems

In order to achieve higher system energy efficiency （EE）,a new coordinated multipoint （CoMP）-transmission-based scheme selection energy saving （CTSES）algorithm is proposed for downlink homogeneous cellular networks.The problem is formulated as an optimization of maximizing system EE,under the constraints of the data rate requirement and the maximum transmit power.The problem is decomposed into power allocation and alternative scheme selection problems.Optimal power allocation is calculated for CoMP-JT （joint transmission）and CoMP-CS （coordinated scheduling） transmissions,and the scheme with higher EE is chosen. Since the optimal problem is a nonlinear fractional optimization problem for both CoMP transmission schemes, the problem is transformed into an equivalent problem using the parametric method. The optimal transmit power and optimal EE are obtained by an iteration algorithm in CoMP-JT and CoMP-CS schemes.Simulation results show that the proposed algorithm offers obvious energy-saving potential and outperforms the fixed CoMP transmission scheme.Under the condition of the same maximum transmit power limit,the empirical regularity of user distribution for scheme choice is presented, and using this regularity, the computational complexity can be reduced.

煤岩反射率自动测定的研究

在研究显微光度计的自动聚焦方法和分析煤岩反射率自动测定中存在的各种无效测点的特点基础上，通过试验研究，确定了去除无效测点的方法，并在ＭＰＭ４００显微光度计上，开发了一套能自动扫描、自动聚焦的煤岩反射率自动测定系统。

Superposition Effect of Passive Intermodulation for Cable Assemblies with Discrete Point-Sources

In order to expand the cell coverage of wireless cellular systems, the number of passive components in wireless systems has been substantially increased. There can be many passive intermodulation(PIM) pointsources even in a device or a radio link, which may add up constructively or destructively. A modified point-source model with lossy components is proposed to evaluate the superposition effect of the forward and refl ected PIM in case of series connection. The index of the series connection factor(SCF) is employed for systems that incorporate multiple PIM sources to predict the important characteristics of the cumulative PIM, such as the maximum and minimum values and the limit form. Furthermore, some initial experimental results are given out and the deviation in the above-mentioned prediction is also analyzed.

Energy Efficient Access Point Selection and Signal Projection for Accurate Indoor Positioning

We propose a method to improve positioning accuracy while reducing energy consumption in an indoor Wireless Local Area Network(WLAN) environment.First,we intelligently and jointly select the subset of Access Points(APs) used in positioning via Maximum Mutual Information(MMI) criterion.Second,we propose Orthogonal Locality Preserving Projection(OLPP) to reduce the redundancy among selected APs.OLPP effectively extracts the intrinsic location features in situations where previous linear signal projection techniques failed to do,while maintaining computational efficiency.Third,we show that the combination of AP selection and OLPP simultaneously exploits their complementary advantages while avoiding the drawbacks.Experimental results indicate that,compared with the widely used weighted K-nearest neighbor and maximum likelihood estimation method,the proposed method leads to 21.8%(0.49 m) positioning accuracy improvement,while decreasing the computation cost by 65.4%.

Clustering Approaches for Overhead Reduction over Coordinated Multiple Points Network-MIMO Downlink Systems

Owing to the potential for intercell cochannel interference mitigation and significant spectral efficiency improvement, coordinating transmission techniques by multiple radio access points have recently attracted a lot of attention. In this paper, the system structure and mathematical signal model based on clustered structure are presented for multipoint coordinating downlink transmission, the clustered supercell configurations with static/dynamic approaches are discussed, and then optimal precod- ing design is provided for an accepted level of scheduling complexity and reduced signaling over- head. Some simulation results are given to evaluate the performance of different cell-clustering approaches, and to show that a clustered supercell size of 7 is a reasonable choice for clustered coordination with the given transmit power and the reduced feedback.