Improved resolution of the multiple inverse method by eliminating erroneous solutions

The multiple inverse method is a numerical technique designed to separate stresses from heterogeneous fault–slip data. The method is one of the resampling methods based on the pattern recognition. Plotting solutions determined from k-fault subset into the parameter space, we have clusters representing significant stresses for the dataset. This paper presents a technique to improve the resolution of stress for the method. The regularity/singularity test of the subsets taken from the fault–slip data is the key for this purpose. The resolution and accuracy of the method are improved by eliminating erroneous stresses or artifacts that were yielded by the method. The performances of the method are demonstrated with a variety of artificial datasets.     

利用仿真方法研究三频信标技术

为了探究三频信标反演高精度电离层电子浓度总含量（total electron content, TEC）的理论过程并分析不同观测误差对反演精度产生的影响,通过仿真卫星信号多普勒频移的方法来进行三频信标技术反演TEC的研究.通过已知的卫星轨道坐标、接收站坐标、卫星高度角与电离层背景信息,利用信号传播规律,仿真得到信号传播过程中的多普勒频移信息,解算出相对TEC;再利用多站法估计相位积分常数,解算双频绝对TEC;而后利用多普勒相移小数部分与三频相位积分常数结合,解算高精度三频TEC.将反演的三频TEC值与先验背景电离层TEC值进行比对,在6°观测误差的情况下,三频反演的TEC差值相对平均值在4.5%以内,相对RMS在6%以内,结果表明三频信标技术可以有效提高TEC反演精度.     

Exploiting information extraction techniques for automatic semantic video indexing with an application to Turkish news videos

This paper targets at the problem of automatic semantic indexing of news videos by presenting a video annotation and retrieval system which is able to perform automatic semantic annotation of news video archives and provide access to the archives via these annotations. The presented system relies on the video texts as the information source and exploits several information extraction techniques on these texts to arrive at representative semantic information regarding the underlying videos. These techniques include named entity recognition, person entity extraction, coreference resolution, and semantic event extraction. Apart from the information extraction components, the proposed system also encompasses modules for news story segmentation, text extraction, and video retrieval along with a news video database to make it a full-fledged system to be employed in practical settings. The proposed system is a generic one employing a wide range of techniques to automate the semantic video indexing process and to bridge the semantic gap between what can be automatically extracted from videos and what people perceive as the video semantics. Based on the proposed system, a novel automatic semantic annotation and retrieval system is built for Turkish and evaluated on a broadcast news video collection, providing evidence for its feasibility and convenience for news videos with a satisfactory overall performance.     

基于QT的机载三维激光扫描仪软件系统设计

随着测绘技术的发展,利用机载三维激光扫描仪获取点云数据,从点云数据中提取模型信息成为现代测绘技术的一种发展趋势. 点云数据处理的相关应用也越来越多,点云数据的处理软件参差不齐,需求和功能也各不相同. 针对上述问题,在基于QT编程平台下,利用PCL开发机载三维激光扫描仪点云数据处理软件,集中处理点云数据. 该系统由点云数据读写、三维显示、点云滤波、网格重构、点拾取、点云分割及NARF关键点提取等功能模块组成. 各模块采用面向对象的思想设计,功能易于扩展,以完成进一步的测绘工作. 实践表明,该系统具有良好的工程实用价值,可以快速完成机载三维激光扫描仪的数据处理工作.     

Experimental characterization of the small strain shear modulus of soft clay stabilized with cement and nano-SiO2 using bender element tests

Bulletin of Engineering Geology and the Environment - The accurate and efficient modification of the static and dynamic properties of problematic soils is a primary concern in geotechnical...     

Distance estimation with mixed real and virtual targets in stereoscopic displays

In this paper we investigated the accuracy of center-to-center distance perception in near field augmented reality visual targets viewed by stereoscopic glasses. One real and one virtual targets were presented in four layout or target orientations (two horizontal and two vertical, by altering the relative positions of real and virtual targets) at three different parallax conditions (on screen, 5 cm from screen and 10 cm from screen) and four levels of scaled between targets’ distance (10–20 cm, 20–30 cm, 30–40 cm and 40–50 cm). The result revealed overall underestimation with an accuracy of about 84%. Interestingly, it was noticed that the main effects of layout, parallax and center-to-center distance were significant. Generally, accuracy improves when targets put vertical, close to observers’ position and smaller separation of targets. Significant interactions among the three main factors were also reported. The results are of great importance as it provides guide for the developers to decide where to present targets depending on the need for relative accuracy of judgment. Some engineering implications of the result are also discussed in this paper.     

Optimization of the polymer concrete used for manufacturing bases for precision tool machines

Due to its superior damping ratio, high adhesion and fast curing, polymer concrete is used in manufacturing bases for a wide range of precision machines. The coefficient of thermal expansion for polymer concrete is one of the main parameters that can affect the level of accuracy in precision tool machines. Flexural strength is a fundamental strength of the base. In this study six aggregates (basalt, spodumene, fly ash, river gravel, sand and chalk) were investigated. Polymer concrete samples were prepared with different compositions of aggregates containing the same resin volume fraction (aggregates 83% and risen 17%). A four points flexural test was employed to measure the flexural strength of the polymer concrete samples. The coefficient of thermal expansion for polymer concrete was measured using a custom built device. The preliminary optimum composition, with the highest flexural strength and lowest thermal expansion coefficient, was found to be basalt, spodumene and fly ash. Basalt, sand and fly ash composition was the second in the rank. The second composition was nominated for further optimization in terms of resin volume fraction in consideration of its ability to adapt a smaller amount of resin. Different samples of polymer concrete were prepared with a variety of resin volume fractions as follows; 17%, 15% and 13%. The resin volume fraction has been demonstrated to have a significant effect on the coefficient of thermal expansion and flexural strength for polymer concrete. The final optimized composition was basalt, sand and fly ash (filler 87% and resin 13%). ANSYS 13 software was employed in visualizing the influence of polymer concrete compositions on the thermal expansion of the base and how it affected the level of precision of the tool machine.     

盾构隧道衬砌的设计方法分析

针对盾构隧道衬砌管片的内力及变形受多种因素影响的情况,结合工程实例,从衬砌管片方面分析了衬砌的内力及变形,得出衬砌管片的内力及变形随其自身因素变化的一些规律,以供设计人员参考。