The influence of topography and land use on water quality of Xiangxi River in Three Gorges Reservoir region

A self-organizing map (SOM) was used to cluster the water quality data of Xiangxi River in the Three Gorges Reservoir region. The results showed that 81 sampling sites could be divided into several groups representing different land use types. The forest dominated region had low concentrations of most nutrient variables except COD, whereas the agricultural region had high concentrations of NO3N, TN, Alkalinity, and Hardness. The sites downstream of an urban area were high in NH3N, NO2N, PO4P and TP. Redundancy analysis was used to identify the individual effects of topography and land use on river water quality. The results revealed that the watershed factors accounted for 61.7% variations of water quality in the Xiangxi River. Specifically, topographical characteristics explained 26.0% variations of water quality, land use explained 10.2%, and topography and land use together explained 25.5%. More than 50% of the variation in most water quality variables was explained by watershed characteristics. However, water quality variables which are strongly influenced by urban and industrial point source pollution (NH3N, NO2N, PO4P and TP) were not as well correlated with watershed characteristics.

Response Specificity to Advertisement Vocalization in the Chinese Alligator (Alligator sinensis)

Stringency in the identification of conspecific call properties is essential among sympatric species to ensure conspecific mating, as the risk of improper recognition and heterospecific mating is high. In this study we investigated the basic signal structure required for intraspecies communication in the Chinese alligator (Alligator sinensis), a species that has no relatives living in sympatry, by playback of signals modified in the temporal (truncating original bellows with first 1/4, 1/2, 3/4 or last 1/4, 1/2, 3/4 portion) or frequency domain (with low- or high-pass filters at frequencies 100, 250, 500 and 1000 Hz), or by reversal of natural bellows. The playback experiments revealed that relatively large modifications in bellow temporal or frequency structure failed to impair Chinese alligators' bellowing behavior; even reversed bellows effectively evoked a positive response. In general, the first half of the bellow in temporal domain and frequencies below 500 Hz were critical for behavioral induction, while the last half of the bellow in temporal domain and frequencies above 500 Hz failed to produce a single positive response, implying a potential functional signal redundancy. The observed high tolerance to bellow variations in Chinese alligators may be an evolutionary adaptation to (1) the acoustic constraints of propagation imposed by dense vegetative habitats; or (2) a lack of selection pressure due to the low risk of incorrect conspecific recognition and heterospecific mating.

Zebrafish eaf1 and eaf2/u19 Mediate Effective Convergence and Extension Movements through the Maintenance of wnt11 and wnt5 Expression

Studies have attributed several functions to the Eaf family, including tumor suppression and eye development. Given the potential association between cancer and development, we set forth to explore Eaf1 and Eaf2/U19 activity in vertebrate embryogenesis, using zebrafish. In situ hybridization revealed similar eaf1 and eaf2/u19 expression patterns. Morpholino-mediated knockdown of either eaf1 or eaf2/u19 expression produced similar morphological changes that could be reversed by ectopic expression of target or reciprocal-target mRNA. However, combination of Eaf1 and Eaf2/U19 (Eafs)-morpholinos increased the severity of defects, suggesting that Eaf1 and Eaf2/U19 only share some functional redundancy. The Eafs knockdown phenotype resembled that of embryos with defects in convergence and extension movements. Indeed, knockdown caused expression pattern changes for convergence and extension movement markers, whereas cell tracing experiments using kaeda mRNA showed a correlation between Eafs knockdown and cell migration defects. Cardiac and pancreatic differentiation markers revealed that Eafs knockdown also disrupted midline convergence of heart and pancreatic organ precursors. Noncanonical Wnt signaling plays a key role in both convergence and extension movements and midline convergence of organ precursors. We found that Eaf1 and Eaf2/U19 maintained expression levels of wnt11 and wnt5. Moreover, wnt11 or wnt5 mRNA partially rescued the convergence and extension movement defects occurring in eafs morphants. Wnt11 and Wnt5 converge on rhoA, so not surprisingly, rhoA mRNA more effectively rescued defects than either wnt11 or wnt5 mRNA alone. However, the ectopic expression of wnt11 and wnt5 did not affect eaf1 and eaf2/u19 expression. These data indicate that eaf1 and eaf2/u19 act upstream of noncanonical Wnt signaling to mediate convergence and extension movements.

Simulation of single electronic device and robust circuit construction

The article mainly focuses on the simulation of the single electron device and circuit. The orthodox model of single electronic device is introduced and the simulation with Matlab and Pspice is illustrated in the article. Moreover, the built of robust circuit using single electronic according to neural network is done and the simulation is also included in the paper. The result shows that neural network added with proper redundancy is an available candidate for single electron device circuit. The proposed structure is also promising for the realization of low ultra-low power consumption and solution of transient device failure.

Proposed scheme for parallel 10Gb/s VSR system and its Verilog HDL realization

This paper proposes a novel and innovative scheme for 10Gb/s parallel Very Short Reach (VSR) optical communication system. The optimized scheme properly manages the SDH/SONET redundant bytes and adjusts the position of error detecting bytes and error correction bytes. Compared with the OIF-VSR4-01.0 proposal, the scheme has a coding process module. The SDH/SONET frames in transmission direction are disposed as follows: (1) The Framer-Serdes Interface (FSI) gets 16x622.08Mb/s STM-64 frame. (2) The STM-64 frame is byte-wise stripped across 12 channels, all channels are data channels. During this process, the parity bytes and CRC bytes are generated in the similar way as OIF-VSR4-01.0 and stored in the code process module. (3) The code process module will regularly convey the additional parity bytes and CRC bytes to all 12 data channels. (4) After the 8B/10B coding, the 12 channels is transmitted to the parallel VCSEL array. The receive process approximately in reverse order of transmission process. By applying this scheme to 10Gb/s VSR system, the frame size in VSR system is reduced from 15552x12 bytes to 14040x12 bytes, the system redundancy is reduced obviously.

一种XACML规则冲突及冗余分析方法

基于属性的声明式策略语言XACML表达能力丰富,满足开放式环境下资源访问管理的复杂安全需求,但其自身缺乏对规则冲突检测、规则冗余分析的支持.文中利用规则状态思想描述分析了属性层次操作关联带来的多种冲突类型,在资源语义树策略索引基础上利用状态相关性给出规则冲突检测算法;利用状态覆盖思想分析造成规则冗余的原因,给出在不同规则评估合并算法下的冗余判定定理.仿真实验首先分析了冲突检测算法的运行效率;然后针对多种策略判定系统,验证了基于语义树的策略索引和冗余规则处理可以显著提高判定性能.

Construction of 2-D directional filter bank by cascading checkerboard-shaped filter pair and CMFB

In this paper, we propose a new approach to construct a 2-dimensional (2-D) directional filter bank (DFB) by cascading a 2-D nonseparable checkerboard-shaped filter pair and 2-D separable cosine modulated filter bank (CMFB). Similar to diagonal subbands in 2-D separable wavelets, most of the subbands in 2-D separable CMFBs, tensor products of two 1-D CMFBs, are poor in directional selectivity due to the fact that the frequency supports of most of the subband filters are concentrated along two different directions. To improve the directional selectivity, we propose a new DFB to realize the subband decomposition. First, a checkerboard-shaped filter pair is used to decompose an input image into two images containing different directional information of the original image. Next, a 2-D separable CMFB is applied to each of the two images for directional decomposition. The new DFB is easy in design and has merits: low redundancy ratio and fine directional-frequency tiling. As its application, the BLS-GSM algorithm for image denoising is extended to use the new DFBs. Experimental results show that the proposed DFB achieves better denoising performance than the methods using other DFBs for images of abundant textures. (C) 2008 Elsevier B.V. All rights reserved.

集群技术在电力综合自动化系统中的应用研究

介绍了一种利用集群技术实现双机容错的开发方法.通过对集群技术运行机制的深入研究,提出了采用基于"层"模式的双机容错系统技术方案,在普通PC服务器上实现了双机容错系统,分析了该系统的可用性,针对电力综合自动系统的结构特点,对心跳侦测等功能进行了改进,并在一套小型变电站自动化系统上进行了实验验证,能够较好的满足中小型电力综合自动化系统的需求.

一种高效覆盖的水下传感器网络部署策略

传感器节点的部署直接关系到水下传感器网络的成本和性能。考虑到传感器节点间具有很强的协同能力,该文提出一种基于检测融合的部署策略。采用Neyman-Pearson准则融合单元网格内所有传感器节点的检测信息,实现正方形和正三角形两种单元网格的高效覆盖,进而分别给出针对两种单元网格的监测区域网格划分方法,从而确定监测区域需要的传感器节点数量以及放置的具体位置。通过仿真实验验证了该部署策略的有效性。结果表明,与不采用检测融合时相比,降低了传感器节点冗余度。使用相同数量的传感器节点,新的部署策略能够在保证一定感知质量的基础之上获得更大的覆盖范围。

高可用性工业以太网技术的研究与实现

针对现场总线控制系统对高可靠性和稳定性的要求会限制工业以太网的应用问题,在原有网络的基础上添加一个并行的冗余链路,以增强通信的可用性,减小通信链路故障对系统运行的影响。结合EPA通信协议栈,设计并行网络冗余解决方案,包括协议栈结构、帧结构和通信过程。给出该方案的性能分析。

具有万向机构的蛇形机器人运动控制

设计了一种能够使蛇形机器人运动更灵巧、奇异点更少和运动能力更强的机构 ,对具有三个自由度的新型蛇形机器人单元进行了改进 ,在单元上增加被动轮机构 ,使其具有万向机构的特点。该单元不仅能够用被动轮驱动机器人运动 ,而且增加了类似于主动轮的驱动机构 ,克服了被动轮驱动能力弱的缺点 ,增强了机器人的运动能力。在分析非完整约束的基础上 ,对蛇形机器人的运动学和冗余度进行分析 ,提出了控制该类蛇形机器人运动的分解矩阵方法和分组交替运动法。

一种离散驱动蛇形柔性臂的工作空间及优化设计研究

以一种离散驱动蛇形柔性臂为研究对象 ,分析并提出了弯曲型离散驱动机器人工作空间的表达方法。考虑到离散驱动机器人工作空间的离散性 ,为了便于对其运动学参数进行调整 ,以使末端操作器达到新指定的工作位置 ,提出了参数调整“标定”的概念 ,并依据使运动学参数调整值尽量小的优化原则对运动学参数进行了优化设计 ,从而解决了运动学参数设计的冗余度问题。

基于关节限位的自治水下机器人机械手系统运动规划研究

对自治水下机器人搭载的四功能水下电动机械手进行了简要描述。考虑到自治水下机器人机械手系统的运动学冗余,将关节限位算法用于系统逆运动学求解,避免载体大幅度姿态变化。利用Matlab仿真表明该算法在解决系统冗余的同时有效的限制了关节位移。

基于模糊推理水下作业系统运动控制研究

水下作业系统是运动学冗余系统,本文将模糊推理方法融入基于任务优先运动学控制算法,对系统载体与机械手进行协调运动分配,同时对系统多个任务进行优化。通过带有3自由度水下机械手的水下作业系统进行算例仿真研究,说明运动控制算法的有效性。