GPS一机多天线变形监测系统

介绍了作者研制的GPS一机多天线监测系统。GPS已被证明是监测高危边 坡稳定性的一个有效工具，它可以提供比其他测量手段更高的精度。然而，传统的GPS在边 坡监测方面也有其不足，主要在于大规模监测中每个监测点都需要安放GPS接收机，造成成 本过高，因此有明显的局限性。针对以上问题，文中提出了以一台GPS接收机连接监测点上 的多天线序列的新方法，并研制出了专用的多天线转换器。试验结果表明定位精度可达2 mm ～3 mm。     

晶粒细化对Cr-25Nb合金高温氧化行为的影响

采用电弧熔铸和机械合金化+热压烧结技术制备晶粒尺寸相差较大的Cr-25Nb合金,研究其在950及1200 ℃空气中的氧化行为。结果表明,熔铸态及机械合金化Cr-25Nb合金氧化后均没有发生Cr的单一外氧化,而形成了以Cr2O3为外层、NbCrO4为内层的双层氧化膜结构;机械合金化Cr-25Nb合金在950及1200 ℃的氧化速度均小于熔铸态合金,特别是在1200 ℃氧化100 h后,熔铸态Cr-25Nb合金的氧化增重是机械合金化合金的2倍多。这主要是因为晶粒细化促进了氧化膜内应力的释放,提高了氧化膜与基体的粘附性     

引入耦合梯度保真项的非线性扩散图像去噪方法

利用二阶的非线性扩散方程进行图像去噪易产生具有"阶越效应"的去噪结果,也即使分段光滑的图像变为分段常量的.针对低阶非线性扩散去噪方法的不足,通过在原有的扩散方程中引入从梯度保真约束项导出的Euler-Lagrange方程,提出了耦合梯度保真项的非线性扩散图像去噪方法.由于梯度保真约束项考虑了去噪前后图像梯度的相似度,利用该模型能够在保持边缘的同时得到分段光滑的结果,使视觉效果更自然.证明了新模型是一个凸函数,从而保证了最优解的存在性和惟一性.还分析了从噪声图像估计梯度时引入空间正则化对最终结果的影响,并且从理论和实验两个角度分析了合理选择正则化参数的重要性.模型在有界变差函数空间中可积,使得新方法克服了高阶非线性扩散去噪方法易造成边界泄漏以及破坏图像中纹理等高频成分的不足.实验结果表明,通过耦合梯度保真项能够很好地防止"阶越效应"的产生,同时保持图像中的边缘、纹理等结构信息.     

Effect of Y<Subscript>2</Subscript>O<Subscript>3</Subscript> particles on microstructure formation and shear properties of Sn-58Bi solder

In the present study, varying weight percentages of Y₂O₃ particles (3–5 μm) from 0 to 3% were incorporated into eutectic Sn-Bi solder matrix to form composite solders. It is found that the reinforcement particles were well dispersed in the solder matrix. They depressed the growth of intermetallic compound (IMC) layers and reduced the size of IMC grains. Since the Y₂O₃ particles serve as additional nucleation sites for the formation of primary Bi-rich phase, the size of both Bi-rich phase and the IMCs were decreased gradually with the Y₂O₃ content increasing. Shear tests were also conducted on as—soldered joints. The growth of solid-state intermetallic compounds layer was examined by thermal aging of the solder/Cu couple for a temperature range from 60 to 120°C and time periods from 50 to 500 h. Compared with Sn-58Bi solder, finer eutectic microstructures were obtained with Y₂O₃ addition after long time aging. The apparent activation energies calculated for the growth of the intermetallic compound layers were 72 ± 5 kJ/mol of Sn-58Bi, 74 ± 4 kJ/mol of Sn-58Bi-0.5wt%Y₂O₃, 81 ± 5 kJ/mol of Sn-58Bi-1wt% Y₂O₃ and 81 ± 7 kJ/mol of Sn-58Bi-3wt.% Y₂O₃, respectively.     

薄包层长周期光纤光栅的研究

报道了在薄包层光纤上用高频CO2激光脉冲写入的长周期光纤光栅(LPFG),并分析了该类薄包层LPFG横截面折射率的分布.结合LPFG的腐蚀实验,通过传输谱图的比较发现:较先写入光栅后腐蚀光纤包层的方法,先腐蚀光纤包层后写入光栅的方法更能有效地调整谐振波长.进一步研究发现薄包层LPFG对环境折射率的敏感度更高.     

信息可视化和可视分析:挑战与机遇——北戴河信息可视化战略研讨会总结报告

由天津大学软件学院发起并召集,东北大学秦皇岛分校和燕山大学承办的信息可视化战略研讨会于2012年6月9～10日在北戴河成功举行.本文总结了此次会议的讨论内容和达成的共识,对当前信息可视化和可视分析领域的挑战和国际上这方面的研究方向做了大致的分析,并对今后信息可视化和可视分析的大方向提出一些建议,以及对具体行动提出一系列倡议.     

工业以太网交换机不间断供电系统设计

针对工业以太网交换机对供电电源质量要求较高的问题,设计了一种工业以太网交换机不间断供电系统;详细介绍了该系统硬件电路即直流稳压供电电路、蓄电池充电管理控制电路、蓄电池温度检测电路、电源切换电路、CAN总线通信电路和单片机控制电路的设计,并给出了该系统主程序流程。试验结果表明,该系统具有动态响应快、静态功耗小等特点,可满足复杂环境下的工业以太网交换机供电需求。     

Kernel Function in SVM-RFE based Hyperspectral Data band Selection

Supporting vector machine recursive feature elimination (SVM-RFE) has a low efficiency when it is applied to band selection for hyperspectral dada,since it usually uses a non-linear kernel and trains SVM every time after deleting a band.Recent research shows that SVM with non-linear kernel doesn’t always perform better than linear one for SVM classification.Similarly,there is some uncertainty on which kernel is better in SVM-RFE based band selection.This paper compares the classification results in SVM-RFE using two SVMs,then designs two optimization strategies for accelerating the band selection process:the percentage accelerated method and the fixed accelerated method.Through an experiment on AVIRIS hyperspectral data,this paper found:① Classification precision of SVM will slightly decrease with the increasing of redundant bands,which means SVM classification needs feature selection in terms of classification accuracy;② The best band collection selected by SVM-RFE with linear SVM that has higher classification accuracy and less effective bands than that with non-linear SVM;③ Both two optimization strategies improved the efficiency of the feature selection,and percentage eliminating performed better than fixed eliminating method in terms of computational efficiency and classification accuracy.     

融合分时电价的居民可控负荷优先级控制策略

在智能电网背景下,智能终端及智能家电大规模普及导致家庭用电量大幅增加,为应对电力负荷高峰逐年攀升,缓解电力供应趋紧的压力,合理利用用户侧大量可控负荷资源参与需求响应对电网的运行和发展有重要意义.提出基于智能家庭能量管理系统的融合分时电价的居民可控负荷优先级控制策略,对家庭中多类可控负荷(空调、热水器、电动汽车、洗衣机、...     

保留色彩细节的多义图像混合系统研究

提出了一个通过保留全部频带信息来保留色彩细节的多义图像合成系统。系统依据两个用户给定的视距或视角将不同含义的两个目标图像合成一幅多义图像。首先,通过视距和图像高度的函数来选择小波分解级,从而对目标图像进行小波分解;其次,根据可选的融合规则和权值变量融合并重构出在两个视角下的多义图像;最后,采取均值降噪的方法滤除结果图像噪波。实验证明,该系统能高效合成视觉效果醒目的图像并充分保留原目标图像的色彩和细节特征,有利于满足商用需求。