An ICPSO-RBFNN nonlinear inversion for electrical resistivity imaging

To improve the global search ability and imaging quality of electrical resistivity imaging(ERI) inversion, a two-stage learning ICPSO algorithm of radial basis function neural network(RBFNN) based on information criterion(IC) and particle swarm optimization(PSO) is presented. In the proposed method, IC is applied to obtain the hidden layer structure by calculating the optimal IC value automatically and PSO algorithm is used to optimize the centers and widths of the radial basis functions in the hidden layer. Meanwhile, impacts of different information criteria to the inversion results are compared, and an implementation of the proposed ICPSO algorithm is given. The optimized neural network has one hidden layer with 261 nodes selected by AKAIKE's information criterion(AIC) and it is trained on 32 data sets and tested on another 8 synthetic data sets. Two complex synthetic examples are used to verify the feasibility and effectiveness of the proposed method with two learning stages. The results show that the proposed method has better performance and higher imaging quality than three-layer and four-layer back propagation neural networks(BPNNs) and traditional least square(LS) inversion.     

XML在并行骨架描述中的应用

在对并行骨架的思想、描述和应用进行深入研究的基础上,本文提出了一种基于XML的并行骨架描述方法,为基于骨架的并行编程系统中各种骨架描述提供了一种统一的处理模型,对提高并行骨架库的通用性、可扩展性和可移植性具有重要意义.     

进口贸易对我国经济增长影响的实证分析

长期以来,人们都把关注的焦点放在出口贸易上,而进口贸易对经济增长的作用一直为人们所忽视。本文通过对进口贸易与经济增长两者关系的实证分析,证明了两者之间存在着显著的相关,对缓解发展中国家经济发展的供给瓶颈、提高科技水平、增进社会福利水平等方面都有明显的推动作用。并在此基础上根据我国对外贸易的现实情况,提出了促进进口贸易发展的建议。     

浅谈施工升降机起重量限制器

为了人员和货物以及升降机本身的安全,施工升降机国家标准GB/T10054-2005为防止施工升降机超载运行,做了严格的规定.     

基于0-1背包问题的两种算法

0-1背包问题是组合优化领域里的一个典型问题,是属于易于描述却难于解决的NP难题,有效解决0-1背包问题具有重要意义。首先给出了0-1背包问题的描述,然后详细介绍了回溯法和分支限界法的算法思想和搜索策略,并对两种算法进行了比较和分析。     

Nonlinear inversion for electrical resistivity tomography based on chaotic DE-BP algorithm

Nonlinear resistivity inversion requires efficient artificial neural network （ANN） model for better inversion results. An evolutionary BP neural network （BPNN） approach based on differential evolution （DE） algorithm was presented, which was able to improve global search ability for resistivity tomography 2-D nonlinear inversion. In the proposed method, Tent equation was applied to obtain automatic parameter settings in DE and the restricted parameter Fcrit was used to enhance the ability of converging to global optimum. An implementation of proposed DE-BPNN was given, the network had one hidden layer with 52 nodes and it was trained on 36 datasets and tested on another 4 synthetic datasets. Two abnormity models were used to verify the feasibility and effectiveness of the proposed method, the results show that the proposed DE-BP algorithm has better performance than BP, conventional DE-BP and other chaotic DE-BP methods in stability and accuracy, and higher imaging quality than least square inversion.     

可编程的网络数字音频系统

1 引言 数字音频信号处理设备是专业音响系统的重要组成部分,也是系统调试的关键设备。传统的信号处理方法是把不同功能、不同用途的各种处理设备用很多专用电缆与调音台和功放等设备互联组成一个扩声系统。90年代中、后期,随着数字信号处理技术（DSP）的不断提高及PC机的普及和发展,集成数字信号处理器（Integrated Digital Signal processor）获得了迅速发展。例如,美国的MERLIN ISP100在一个机箱中设置了图像式均衡器（GEQ）、参数均衡器（PEQ）、延时器、压缩／限幅器、增益控制器和多个I／O模块等硬件装置;在Windows…     

基于直流平衡的电泳电子纸驱动波形的优化研究

随着人们对于生活品质要求的提高,便利、护眼、能耗低的电子纸显示技术在显示技术领域越来越受人们追捧。电子纸的显示是通过一系列的驱动波形来实现,即不同的灰阶通过不同的电压驱动序列驱动而得到。在驱动波形的设计中不仅要考虑到显示效果,还要考虑到刷屏响应速度、闪烁和直流平衡的影响。本文提出了一种新的驱动波形设计方案,不仅达到了直流平衡,消除了可能积累电荷对于显示屏的影响,同时提高了刷屏的速度,减少了25%的闪烁,也保证了显示效果。     

非静止轨道广播卫星系统IMT-2000干扰分析

由于非静止轨道广播卫星系统NGSO-BSS与第三代移动通信系统IMT-2000的使用频段部分重叠,因此会产生系统间干扰,导致IMT-2000系统性能下降.为保证两系统共存,以日本拟发送的非静止轨道广播卫星系统为背景,建立了卫星系统对地面移动通信系统的干扰模型,用于分析该系统干扰地面同频段IMT-2000导致的上下行覆盖损失,并以此给出了能够保护IMT-2000系统的有效卫星发射PFD限值.