活性炭毡布的研制与开发   总被引：1，自引：0，他引：1  

袁玮  林家辉 《铀矿地质》2000,16(3):187-192

采用浸渍工艺 ,利用活性炭、粘合剂、无纺布 3种原料 ,可研制出一种复合高效吸附过滤材料———活性炭毡布。本文介绍了该产品的生产工艺流程 ,并对产品研制过程中影响产品性能的各种因素加以分析讨论。  相似文献   

基于多台站OH全天空气辉成像仪观测的中国中纬地区重力波传播特性   总被引：4，自引：2，他引：2       下载免费PDF全文

王翠梅  李钦增  徐寄遥  袁韡 《地球物理学报》2016,59(5):1566-1577

利用位于中国中纬地区6个OH气辉成像仪2012年1月至2013年12月两年的观测数据,我们研究分析了重力波传播特征.结果表明重力波的水平波长、观测周期和水平相速度分别主要分布于10~35km,4~12min和30~100m·s-1范围.夏季,重力波主要沿极向方向传播.然而,冬季,他们有向赤道方向和平行于赤道方向的传播趋势.同时,我们结合TRMM卫星和ECMWF数据,发现在夏季重力波的北向传播趋势可能主要由观测台站南方的对流活动导致.然而,对流层顶附近的急流可能在冬季重力波的主要传播方向方面做出较大贡献.分析结果也表明,低层-中层大气背景风的滤波效应仅在夏季与中国中纬地区重力波纬向传播方向各向异性吻合较好.  相似文献   

Single-frequency precise point positioning with optimal filtering   总被引：7，自引：0，他引：7  

Anh Quan Le  Christian Tiberius 《GPS Solutions》2007,11(1):61-69

The accuracy of standalone GPS positioning improved significantly when Selective Availability was turned off in May 2000. With the availability of various public GPS related products including precise satellite orbits and clocks, and ionosphere maps, a single-frequency standalone user can experience even a further improvement of the position accuracy. Next, using carrier phase measurements becomes crucial to smoothen the pseudorange noise. In this contribution, the most critical sources of error in single-frequency standalone positioning will be reviewed and different approaches to mitigate the errors will be considered. An optimal filter (using also carrier phase measurements) will be deployed. The final approach will then be evaluated in a decently long static test with receivers located in different regions of the world. Kinematic experiments have also been performed in various scenarios including a highly dynamic flight trial. The accuracy, in general, can be confirmed at 0.5 m horizontal and 1 m vertical, with static tests. Ultimate results demonstrate an accuracy close to 2 dm (95%) for the horizontal position components and 5 dm (95%) for the vertical in the flight experiment.

Anh Quan LeEmail:

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An adaptive surface filter for airborne laser scanning point clouds by means of regularization and bending energy     

《ISPRS Journal of Photogrammetry and Remote Sensing》2014

The filtering of point clouds is a ubiquitous task in the processing of airborne laser scanning (ALS) data; however, such filtering processes are difficult because of the complex configuration of the terrain features. The classical filtering algorithms rely on the cautious tuning of parameters to handle various landforms. To address the challenge posed by the bundling of different terrain features into a single dataset and to surmount the sensitivity of the parameters, in this study, we propose an adaptive surface filter (ASF) for the classification of ALS point clouds. Based on the principle that the threshold should vary in accordance to the terrain smoothness, the ASF embeds bending energy, which quantitatively depicts the local terrain structure to self-adapt the filter threshold automatically. The ASF employs a step factor to control the data pyramid scheme in which the processing window sizes are reduced progressively, and the ASF gradually interpolates thin plate spline surfaces toward the ground with regularization to handle noise. Using the progressive densification strategy, regularization and self-adaption, both performance improvement and resilience to parameter tuning are achieved. When tested against the benchmark datasets provided by ISPRS, the ASF performs the best in comparison with all other filtering methods, yielding an average total error of 2.85% when optimized and 3.67% when using the same parameter set.  相似文献