Showing papers by "Geophysical Survey published in 2009"

Pinpointing the sources and measuring the lengths of the principal rivers of the world

Abstract: Cultures throughout the world are associating with the rivers. People depend upon the rivers and their tributaries for food, water, transport, and many other aspects of their daily lives. Unfortunately, human beings have not calculated the accurate lengths for the great rivers even today. The lengths of the rivers are very different in popular textbooks, magazines, atlases and encyclopedias, etc. To accurately determine the lengths of the principal rivers of the world, the combination of satellite image analysis and field investigations to the source regions is proposed in this paper. The lengths of the Nile, Amazon, Yangtze, Mississippi, Yellow, Ob, Yenisey, Amur, Congo and Mekong, with lengths over or close to 5000 km, were calculated using the proposed method. The results may represent the most reliable and accurate lengths of the principal rivers of the world that are currently achievable.

Russian eruption warning systems for aviation

Abstract: More than 65 potentially active volcanoes on the Kamchatka Peninsula and the Kurile Islands pose a substantial threat to aircraft on the Northern Pacific (NOPAC), Russian Trans-East (RTE), and Pacific Organized Track System (PACOTS) air routes. The Kamchatka Volcanic Eruption Response Team (KVERT) monitors and reports on volcanic hazards to aviation for Kamchatka and the north Kuriles. KVERT scientists utilize real-time seismic data, daily satellite views of the region, real-time video, and pilot and field reports of activity to track and alert the aviation industry of hazardous activity. Most Kurile Island volcanoes are monitored by the Sakhalin Volcanic Eruption Response Team (SVERT) based in Yuzhno-Sakhalinsk. SVERT uses daily moderate resolution imaging spectroradiometer (MODIS) satellite images to look for volcanic activity along this 1,250-km chain of islands. Neither operation is staffed 24 h per day. In addition, the vast majority of Russian volcanoes are not monitored seismically in real-time. Other challenges include multiple time-zones and language differences that hamper communication among volcanologists and meteorologists in the US, Japan, and Russia who share the responsibility to issue official warnings. Rapid, consistent verification of explosive eruptions and determination of cloud heights remain significant technical challenges. Despite these difficulties, in more than a decade of frequent eruptive activity in Kamchatka and the northern Kuriles, no damaging encounters with volcanic ash from Russian eruptions have been recorded.

The Tectonic Setting of the Triassic Basin in the Helanshan Mts.

Abstract: Based on the latest studies and the analysis on the tectonic events occurring around the Helanshan region,it is concluded that the tectonic setting of the northern Helanshan in the Late Triassic-Early Jurassic may be similar to that of the Yinggehai pull apart basin in the Early-Middle Cenozoic.During the Late Triassic-Early Jurassic,the left lateral strike-slipping of the Bayan-UI Shan-Langshan shearing zone resulted in the uplift of Bayan-Ul Shan,whereas the left lateral strike-slipping resulted in the formation of a pull apart basin in the northern Helanshan as well as deposition of thick Upper Triassic Yanchang Formation and Jurassic strata.Although the northern Helanshan and the Ordos basin may connect with each other geographically,their depositional mechanisms were different;their relationship may be similar to that between the Yinggehai basin and the South China Sea basin.During the Late Jurassic,this pull-apart basin was reversed due to the eastward compression of the Alxa Block.The reason for the left-lateral strike-slipping of the Bayan-Ul Shan-Langshan ductile shear zone was the left-lateral transprssion of the Alxa Block relative to the Ordos Block in the Late Triassic-Early Jurassic.Its dynamics may result from the collision between the Sino-Korean Plate and the Yangtze Plate.This model could explain the strong extension of the northern Helanshan,which was very different from the Ordos basin itself in the Late Triassic-Early Jurassic;provide the reason for the limited distribution of the intraplate tholeiite;and also interpret the relationships between the uplift of the Bayan-Ul Shan and deposition in the northern Helanshan,as well as the deformation along the southern Alxa block during the same time.Regionally,this model can also explain the evolution and related sediments of left-lateral strike-slipping in southern Mongolia in the same time.

Highway Speed Ground Penetrating Radar System Utilizing Air-Launched Antenna and Method of Use

Abstract: Embodiments of the disclosed technology comprise an air-launched antenna system with interference-rejection technology that operates in analog hardware as well as by way of a digital filtering technique. Using an inline analog hardware filter combined with a digital filter, to determine transversal (and/or recursive) coefficients, in a calibration phase, a measurement system may be configured to remove interference and the effects (such as a delay or temperature variation) which result from use of an analog filter. In this manner, the resulting measurements of a composition of road surface are more accurate and useful.

Monitoring the deformation of a landslide with differential SAR interferometry using corner reflectors

Abstract: In order to monitor the surface deformation of Shuping landslide in the Yangtze River Three Gorges area, the method of differential SAR interferometry (DInSAR) using corner reflectors (CR) was applied. 12 CR, including 10 pyramidal corner reflectors (PCR) and 2 asymmetrical cubic corner reflectors (ACCR), were designed, made, and deployed on Shuping landslide. Based on the numerical test and the preliminary analyses of 5 ENVISAT ASAR images, we concluded that: 1) ACCR can provide strong response signal even without the best SAR look angle and is especially fit for the multi-angle applications of DInSAR; 2) given a simple phase model, the least square (LS) method can be used to analyze the CR's differential phase and get the accumulative deformation value.

An improved 1D filtering method for LIDAR point cloud

Abstract: This paper discusses how to separate non-ground points from raw LIDAR point cloud For the purpose of improving processing efficiency and precision, an improved 1-D filtering method is proposed The entire filtering process is divided into eight steps and non-ground points are eliminated progressively In these processing steps, a key-point detection technique is used to segment points in profile Based on thes e profile segments, detailed analysis is utilized to implement segment-oriented filtering innovatively This method makes us e of entire features of segmen tal points for classification, so it is more accuracy and robust than traditional point-by-point classification Two different scale datasets are used to test our method Compared to 1-D labeling method, the proposed method is more effective and efficiency Keywords: LIDAR, 1-D filtering, scan lin e, key point, segmentation INTRODUCTION In the last 10 years, LIDAR technology has been proven as an effective technique for the acquisition of 3D topographic information Combined with a Global Positioning System (GPS) and an Inertial Measur ement Unit (IMU), LIDAR can generate 3D dense, geo-referenced point clouds directly for the reflective terrain surface These point clouds are valuable for several applications For example, LIDAR point clouds can be used to produce DTMs, hydrologic models, 3D urban models, transportation network models, and the like In the most of applications, eliminating non-ground points form original LIDAR footprints is the most important processing technology The process of eliminating non-ground points from the entire LIDAR data to obtain ground points is called LIDAR data filtering (Vosselman, 2000) Many techniques have been developed to deal with points filtering One kind of methods is based on mathematical morphology (Kilian, 1996; Zhang, 2003), points which operated by morphological erosion are compared to original surface to discriminate ground and non-g round points Another grou p of filtering methods is based on the manipulation of Triangulated Irregular Network (Axelsson, P, 1999), ground points are classified through progressive densification of a TIN model The third kind of methods is using hierarchic robust interpolation and surf ace fitting (Kraus and Pfeifer, 1998), terrain surface is fitting by points and iteratively decline to authentic terrain As a lot of filtering methods have been proposed, Sithole and Vosselman (2004 ) compare these methods detailed and test them with standard test datasets Existing algorithms have achieved some success, but due to the high diversity of terrain, the issue of LIDAR points filtering is far from resolved Due to LIDAR points are acquired in scanning mode, discrete points are organized according to scan line Different from the 2D filtering approaches, which process LIDAR points within a 2D neighborhood, 1D filtering methods directly utilize the intrinsic relation of LIDAR points to determine point neighborhood among scan line more quickly J Shan (2005) proposed a one-dimensional (1-D) labeling algorithm to filter LIDAR point This method is computationally efficient, but not always effective In this paper, we propose an improved 1-D filtering algorithm and use two LIDAR datasets to test it Experiments show our algorithm is not only quickly and efficient, bu t also more steady and accurate than the 1-D labeling method

The Research on 1D SNMR Inversion by Tikhonov Regularization Method

Abstract: The surface nuclear magnetic resonance(SNMR) technology is a method that detecting the underground water directly at surface.After discussing the basic inversion problem, this paper achieve the 1D SNMR Tikhonov regularization inverse by conjugate gradient method.The reliability of the Tikhonov regularization method is illuminated by inversing the theory data, data with the noise and the field data.