基于覆盖细化的数值流形法及其在裂纹扩展中的应用

数值流形法是一种基于数学覆盖和物理覆盖的双重覆盖方法,权函数设于数学覆盖上,而位移函数设于物理覆盖上。该文提出了一种基于数值流形法的覆盖细化方法,用来解决二维裂纹扩展问题。对某一待细化流形单元,其加密点是预先确定的,并非所有流形单元均需细化,只有满足一定条件的裂纹前缘单元才有必要进行覆盖细化。所有的细化均基于数学覆盖,覆盖细化过程对于裂纹前缘单元的不同边界条件是不同的。在流形单元进行覆盖细化后,将会产生新的数学覆盖以及相应的物理覆盖和单元。同时,节理环路和接触信息也需要做相应的修正。选取三个常见裂纹扩展的算例进行比较分析,计算结果表明,该文的覆盖细化方法是可行的,相对于原始流形单元而言,裂纹尖端可以处于单元内部,覆盖细化方法获得更高的精度,而不显著地增加未知自由度。

移动网络应对数据海啸的建设策略探讨

移动网络向高速化、宽带化的方向发展。智能终端快速普及,宽带移动用户高速增长,手机应用软件的快速增加,导致移动网络承载的数据量飞速增长。但是如何有效承载数据海啸成为移动网络建设面临的新的挑战。通过分析移动网络数据发展趋势和数据流量增长规律,进而提出适应移动网络技术演进方向,从提高频谱效率、精细覆盖实现无缝体验、多网协同提高网络资源效率这3个方面探讨运营商应对数据流量洪流的建设策略。

Advanced Coverage Optimization Techniques for Small Cell Clusters

Coverage challenge for small considered to be a optlmlzation is a main cell clusters which are promising solution to provide seamless cellular coverage for large indoor or outdoor areas. This paper focuses on small cell cluster coverage problems and proposes both centralized and distributed self-optimization methods. Modified Particle swarm optimization （MPSO） is introduced to centralized optimization which employs particle swarm optimization （PSO） and introduces a heuristic power control scheme to accelerate the algorithm to search tbr the global optimum solution. Distributed coverage optimization is modeled as a non-cooperative game, with a utility function considering both throughput and interference. An iterative power control algorithm is then proposed using game theory （DGT） which converges to Nash Equilibrium （NE）. Simulation results show that both MPSO and DGT have excellent performance in coverage optimization and outperform optimization using simulated annealing algorithm （SA）, reaching higher coverage ratio and throughput while with less iterations.

Location Refinement and Power Coverage Analysis Based on Distributed Antenna

To establish wireless channel suitable for the cabin environment, the power coverage was investigated with distributed antenna system and centralized antenna system based on the actual measurement of channel impulse response. The results indicated that the distributed antenna system has more uniform power coverage than the centralized antenna system. The average relative errors of receiving power of both antennas were calculated. The optimal position of the centralized antenna was obtained by Gaussian function refinement, making the system achieve a better transmission power with the same coverage effect, and providing a reference for antenna location in the future real communication in the cabin.

高分辨率遥感土地覆盖分类技术的应用研究--以重庆市黔江贫困区为例

针对贫困区生态环境与资源的地表覆盖精细化调查需求,本文利用高分辨率遥感影像开展了土地覆盖信息提取的方法和应用研究。重点分析了高分辨率影像均值漂移分割、多特征提取与分析、对象级样本采集以及监督分类等技术,并综合实现了流程化的对象级土地覆盖分类。结果表明,本文串联的高分辨率影像分类技术能生成较精细的土地覆盖专题图,可及时为贫困区生态资源环境评价、碳核算等应用提供较可靠的地表覆盖数据。