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1.
Yao Yevenyo Ziggah Hu Youjian Alfonso Tierra Ahmed Amara Konaté Zhenyang Hui 《Arabian Journal of Geosciences》2016,9(17):698
Two national horizontal geodetic datums, namely, the Accra and Leigon datum, have been the only available datum used in Ghana. These two datums are non-geocentric and were established based on astro-geodetic observations. Relating these different geodetic datums mostly involves the use of conformal transformation techniques which could produce results that are not very often satisfactory for certain geodetic, surveying and mapping purposes. This has been ascribed to the incapability of the conformal models to absorb more of the heterogeneous and local character of deformations existing within the local geodetic networks. Presently, application of new approaches such as artificial neural network (ANN) is highly recommended. Whereas the ANN has been gaining much popularity to solving coordinate transformation-related problems in recent times, the existing researches carried out in Ghana have shown that only three-dimensional conformal transformation methods have been utilized. To the best of our knowledge, plane coordinate transformation between the two local geodetic datums in Ghana has not been investigated. In this paper, an attempt has been made to explore the plane coordinate transformation performance of two different ANN approaches (backpropagation neural network (BPNN) and radial basis function neural network (RBFNN)) compared with two different traditional techniques (six- and four-parameter models) in the Ghana national geodetic reference network. The results revealed that transforming plane coordinates from Leigon to Accra datum, the RBFNN was better than the BPNN and traditional techniques. Transforming from Accra to Leigon datum, both the BPNN and RBFNN produced closely related results and were better than the traditional methods. Therefore, this study will create the opportunity for Ghana to recognize the significance and strength of the ANN technology in solving coordinate transformation problems. 相似文献
2.
Underground coal mining activities in Kozlu Hard Coal Basin have reached a level affecting ground layers inside the mining seams and the surface just above the mining operations, causing movements in vicinity of the basin. The movements emerge as collapsing in vertical direction and as sliding, curling and bending in horizontal direction and are termed mining subsidence since they exhibit themselves in ground layers and on earth surfaces in mining environments. These mining-induced movements cause damages and destructions on structures inside and on the surface of mining grounds, and the dimensions of these damages depend upon quality of structures and magnitude of movements. In order to contribute toward a solution to these problems and to mitigate the effects arising during and after mining activities, one should identify and investigate damage prone movements and determine the movement–time relationship. Therefore, it is immensely important to observe, investigate, and measure these movements in regions where mining activities take place. This study focuses on the surface movement-related deformations on the engineering structures in the basin such as Kozlu Seaport and some part of the Zonguldak-Kozlu Road. For this reason, subsidence monitoring points were established on the engineering structures in the basin in a geodetic network concept, and three periods of precise leveling and static GPS observations were conducted. Analyzing these two types of geodetic observations, active and residual subsidence effects were determined for both Kozlu Seaport and the Road nearby. 相似文献
3.
Jack E. Staples 《Tectonophysics》1986,130(1-4):167-170
Normally, the establishment of national leveling networks was for the purpose of supporting national mapping programs of engineering projects. They are also used as a base on which to establish national gravity networks. During recent years, much study and investigation have been done concerning the characteristics and capabilities of these networks to provide data for determining height velocity changes due to crustal movements.
In the early 1960's the use of automatic (compensator) leveling instruments became common for establishing precise geodetic leveling networks. In 1981, at FIG, Montreux, Professor W.E. Rumpt and Mr. H. Meurisch reported the influence of DC-AC magnetic fields on the line of sight of compensator instruments. As a result, several manufacturers modified their automatic leveling instruments to minimize the AC-DC magnetic effect. Wild Heerbrugg, whose unmodified NA-2 level was least affected by magnetic fields, further reduced the effect by shielding it's compensator.
At the very least, the impact of this discovery will cause national geodetic agencies to modify their existing automatic leveling equipment and possibly embark on a releveling or reanalysis of their existing network. When studying micro/macro earth crustal movements, the geodesist must take this new factor into account in analysing data. 相似文献
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5.
Mostafa Rabah Zaki Zedan Essam Ghanem Ahmed Awad Ahmed Sherif 《Arabian Journal of Geosciences》2016,9(13):613
Nowadays many continuously operating reference stations (CORS) network were established in Middle East to improve the surveying tasks. Establishing such geodetic control networks can be a costly business where multiple stations should be occupied simultaneously and post-processed with scientific software. Recently, precise point positioning (PPP) provides precise positioning values that may be an alternative to precise relative processing. The current research aims to investigate that PPP has a potential as a reliable absolute positioning technique operational simplicity as well as to investigate the capability of PPP approach to be a low cost alternative to the conventional positioning methods used in position determination of core networks stations. In comparison with common relative GPS techniques, the costs are reduced; because no base stations and no simultaneous observations are necessary, no need for control network maintenance which could be the most defective factors that Egypt HARN network suffered from. To see the feasibility study of using PPP for precise determination of the CORS, 14 days of GNSS data for the 14 Kuwait integrated with 27 IGS stations were processed by Bernese software to calculate the precise coordinates of Kuwaiti CORS network in the latest terrestrial geodetic frame. Three days of these data were processed by Trimble business center software and using PPP approach to calculate the precise coordinates of Kuwait network. In the current research, a comparable investigation was carried out between the coordinates obtained from Bernese software, Trimble business center, and PPP approach. The comparison proved high level of agreement between the coordinates which confirm that PPP approach can be applied for establishment of CORS network. 相似文献
6.
Three major fault zones form the Caribbean-South-American plate boundary; these are the Bocono, Moron, and Pilar fault zones. The first geodetic networks were explored and installed in 1972–1973. First measurements were realized in 1973 and remeasurements were made at several intervals up to date. In total 18 sites were studied and explored for local geodetic networks; of these, only five are completely operational, the others are still waiting for monumentation and operation. Nevertheless, for these latter, the main part of the installation, the exploration work and the feasibility studies in geology and topography have already been realized. In the operational networks, the field and point vectors show movements and deformations. Max. values: Yacambu 88 mm/2 years, Mucubaji 32 mm/5 years. The deformational parts of displacements show principally compression vectors from both sides towards the plate boundary. 相似文献
7.
P.F. MacDoran 《Tectonophysics》1979,52(1-4)
Based upon actual transportable radio interferometric geodetic experience using the 9-m diameter ARIES (Astronomical Radio Interferometric Earth Surveying) system, it has been possible to redesign the elements to achieve an order of magnitude more mobility. A new 4-m-diameter ARIES station is now being implemented which will be capable of achieving 4–7 cm three-dimensional accuracy on baselines up to 500 km in virtually all weather conditions. Since the 4-m station remains essentially assembled during redeployments, the elapsed time between data acquisitions is estimated to be three days for sites a few hundred kilometers apart. There is also the capability for rapid deployments to epicentral regions where post-earthquake crustal deformation measurements are desirable.Although the 4-m ARIES station is presently being designed to operate in combination with the 40-m diameter telescope of the Caltech Owens Valley Radio Observatory, further instrumentation improvements in radio sensitivity and higher digital recording rates will allow a 9-m-diameter antenna to function as a transportable base station. This future system will be fully transportable to any global land-based location and be capable of 3-cm three-dimensional relative position measurements on a baseline up to 1000 km with only 8 hours of on-site data acquisition.The cost effectiveness of ARIES technology on geodetic networks of 100-km spacing density is substantially superior by comparison with monitoring such regional scale networks by conventional horizontal and vertical geodetic methods. 相似文献
8.
GPS技术应用于中国地壳运动研究的方法及初步结果 总被引：10，自引：0，他引：10
文中主要就中国利用GPS等空间测地资料研究地壳运动、构造变形 ,以及用于地震预测探索方面 ,从方法技术和近年来取得的一些初步结果进行了概要性论述。介绍了利用GPS技术资料研究地壳水平运动速度场、水平应变场、建立地壳运动模型等方法研究的进展。由GPS观测给出的地壳水平运动初步结果表明 :中国大陆现时水平运动在全球参考系中为整体向东 ,并兼有顺时针扭转运动。西部地区构造形变强烈 ,整个青藏块体及其边界带 ,以及新疆西部是应变值最高的区域 ,水平应变场主压应变优势分布方向为近NE向 ,空间差异显著 ,反映了印度板块碰撞推挤和青藏块体强烈构造运动的影响。中国大陆东部水平运动的差异性不显著。强震分布于地壳运动的大小、方向显著变化的区域 ,大地震通常发生在水平剪应变高值区或其边缘 ,尤其是与区域主干断裂的构造活动背景相一致的剪应变率高值区。 相似文献
9.
Summary Subsidence planning and control must be an integral part of mine design in order to minimize the economic impact of underground mining on the surface. Precalculation of surface deformations which may cause damage to surface structures must be performed and damage criteria must be established, if the response of structures to such movements is to be determined and the extent of damages to be assessed. In this paper the Surface Deformation Prediction System (SDPS), which can be used to predict accurately the vertical and horizontal parameters of surface movements due to underground mining, is discussed. The Subsidence Response Modelling Program (SRMP), which can be applied to evaluate the response of buildings to subsidence-induced movements, is also reviewed. Finally, an example is presented demonstrating the applicability of these techniques for subsidence design and control. 相似文献
10.
《Geoforum》2015
The paper assesses the role for innovation of one aspect which has been generally overlooked by evolutionary economic geography: context. It analyses how context shapes the impact of collaboration on firm-level innovation for 1604 firms located in the five largest city regions of Norway. Specifically, the analysis shows how the benefits to firms of collaborating within regional, national, and international innovation networks are affected by the knowledge endowments of the region within which the firm is located. Using a logit regression analysis, we find, first, that only national and international networking have a significant positive impact on the likelihood of innovation (the former only for process innovation), whereas the regional knowledge endowments have no direct effect. Second, regional cooperation is particularly effective in regions with high investments in R&D, whereas international cooperation is important in regions with an educated workforce – and regional and national collaboration may be ineffective in such cases. We conclude that, in the case of Norway, context is essential in determining the capacity of firms to set up networks and innovate. Regions with an educated workforce can use the resulting absorptive capacity to successfully assimilate knowledge being diffused through global pipelines from faraway places. However, this absorptive capacity is likely to be heavily filtered if regional firms mainly rely on internal connections within Norway. 相似文献
11.
A comparative study for the estimation of geodetic point velocity by artificial neural networks 总被引：1，自引：0，他引：1
Space geodesy era provides velocity information which results in the positioning of geodetic points by considering the time evolution. The geodetic point positions on the Earth’s surface change over time due to plate tectonics, and these changes have to be accounted for geodetic purposes. The velocity field of geodetic network is determined from GPS sessions. Velocities of the new structured geodetic points within the geodetic network are estimated from this velocity field by the interpolation methods. In this study, the utility of Artificial Neural Networks (ANN) widely applied in diverse fields of science is investigated in order to estimate the geodetic point velocities. Back Propagation Artificial Neural Network (BPANN) and Radial Basis Function Neural Network (RBFNN) are used to estimate the geodetic point velocities. In order to evaluate the performance of ANNs, the velocities are also interpolated by Kriging (KRIG) method. The results are compared in terms of the root mean square error (RMSE) over five different geodetic networks. It was concluded that the estimation of geodetic point velocity by BPANN is more effective and accurate than by KRIG when the points to be estimated are more than the points known. 相似文献
12.
A number of geodetic techniques exist for measuring instantaneous crustal motions and deformations. Over distances of a few hundred kilometres, conventional terrestrial methods can achieve accuracies of about 1–2 parts in 106 for horizontal positions, but most existing triangulation networks in Australia are of lower accuracies. Geodetic levelling can provide height‐difference measurements with an accuracy of a few mm for points separated by about 100 km, but actual accuracies are often much lower than this. For points separated by longer distances, from a few 100 km to several 1000 km, space techniques can provide precisions of 5–10 cm. Two experiments carried out in Australia confirm that these precisions can be reached. A laser ranging experiment between sites near Canberra and Perth produced a baseline that is precise to better than 10 cm, and a radio‐interferometry experiment between Canberra, Parkes and Sydney produced baselines with precisions of 10 cm. Further evaluation of both systems is required, but the present results indicate that crustal deformations of the order of 10 cm can be measured with repeat surveys. 相似文献
13.
It is obvious to anyone working on or dealing with underground mining operations, production gaps have to be opened in the ground during mining. The ground layers just above these gaps collapse toward production lines resulting in horizontal and vertical movements both inside and on the earth's surface. These movements are referred to as mining subsidence which eventually causes technical, economic, social and environmental hazards to natural and cultural structures on the surface. It is substantially crucial to the general and regional characteristics of these subsidence occurrences in the underground mining region so it can be possible to mitigate the subsidence induced damages and problems both in the ground and on the surface. Subsidence observations, thus, are conducted inside and on the ground by employing geodetic, geophysical and geotechnical methods with the aim to determine the characteristics and parameters of subsidence occurrence in a region evaluating these subsidence observations. The Zonguldak Hard Coal Basin and Kozlu Coal Production Region within the basin are places where urbanization and underground mining operations are intensively under way. Therefore it is vitally important to continuously monitor the horizontal and vertical displacements formed due to the underground mining in the basin and to determine the subsidence parameters so that it may be possible to forestall the subsidence induced issues that may occur in the near future. This study yields information and computations about the subsidence parameters determined under the light of three periods of geodetic observations carried out in the region. Using the three periods of GPS and precise leveling observations, the average slope angle values resulting from vertical displacements in the study region were obtained from the adjusted coordinates and height differences, and estimated as 16″.67 in positive (+) direction and 18″.03 in negative (−) direction. The horizontal unit deformation parameters, on the other hand, were computed as 0.28 mm/m for the extension parameter while 0.26 mm/m for compression parameter along the routes chosen in the Kozlu region. 相似文献
14.
Since 1996 the Collaborative Research Center (CRC) 461``Strong Earthquakes: A Challenge for Geosciences andCivil Engineering' is funded by the DeutscheForschungsgemeinschaft (German Research Foundation) asa German contribution to the UN initiative``International Decade of Disaster Reduction' (IDNDR).A central project of this CRC is the subproject B1``Three Dimensional Plate Kinematics in Romania', whichis installed to detect borders of the geotectonicplates in Romania, to quantify their three-dimensionalmovement rates and to determine in detail thedeformation of each geotectonic unit in the VranceaRegion as a contribution to the research of thetectonic cause of the intermediate depth earthquakesin this region. These aims shall be accomplished byrepeated GPS-measurements in a network which has beeninstalled in 1997 and measured until now in 1997 and1998. This network is consisting of 26 stations,covering an area of 250 km × 380 km with the Vranceaarea as the centre. The geodetic frame is given by sixstations of the CEGRN (Central European GeodynamicRegional Network) of the CEI-initiative CERGOP, forwhich coordinates and velocities in a global tectonicscenario are available. The paper gives informationabout the tectonic background, the geodetic network,the GPS-measurements and the achieved accuracies andfirst results of deformation analyses. It is shownthat until now no significant deformations could bedetected. But the extension of the GPS network andremeasurements with time intervals of two years willallow statements about the recent crustal movementswithin the lifetime of the CRC 461. 相似文献
15.
《Geoforum》2015
Understanding spatial conceptions is critical to the analysis of local protest strategy formation. Spatialities provoke inquiry into the drivers that may prompt local actors to adhere to particular strategies, and the implications this has on forms of contestation and the way protest is organized. It is argued that local protest can ‘respatialize’ when actors are embedded in social movements and translocal assemblages associated with controversy over development, and that this warrants reconsidering the role of ‘place’. A case study of a proposed megaproject framed in the national interest – a high-speed rail network called HS2, in the United Kingdom – is used to investigate local protest respatialization. Fieldwork was conducted in the Chilterns, an area of high scenic beauty which will be adversely impacted by HS2. The results show how the perceived need to respatialize protest away from the local to the national domain reconfigures debate to focus primarily on economic issues. Respatialization also has implications for the dynamics of protest assemblages with unlikely alliances developing around a need to engage with or engender debate in the national polity. It is concluded that local actors may opt to respatialize their protest in response to their interaction with social movements and protest assemblages that disengage from specific place-based interests. The paper recommends that future research on the geographies of social action take forward spatialization as a powerful lens for investigating protest strategy formation. 相似文献
16.
J. Van Mierlo 《Tectonophysics》1979,52(1-4)
Geodetic networks are designed to obtain data that can be used to monitor crustal movements. The relative position on the earth's surface is determined from these networks by means of coordinates. The coordinates of stations and its variance—covariance matrix are based on the computational model. In spatial networks at least three points, the base points, should be chosen to define the coordinate system “fixed” to the earth. In monitoring crustal movements these base points are considered to be stationary over the time span of the motion involved. A procedure for testing the stability of the base points, together with other stable points, is described.The coordinate differences between two time epochs, t0 and t1 are considered to investigate crustal movements. A statistical test is introduced to determine whether crustal movements have actually occurred.The reliability, i.e., the influence, of nondetected errors in the observations or computations, should be considered. Two types of decisions can be made which may lead to incorrect conclusions. These conclusions are as follows:
- 1. (1) That no movement has taken place, although a nondetected error leads to the opposite conclusion.
- 2. (2) That a movement has occurred, although a nondetected error in the observations leads to the opposite conclusion.
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18.
Being the cause of the loss of life and damaging property, landslide is an important natural hazard. Therefore, landslides have to be monitored and preventive measures taken accordingly. In Geodesy, landslides can be determined with static, kinematic and dynamic geodetic models. The aim of this study is to develop a dynamic geodetic model for landslides and compare it with static and kinematic geodetic models. A study area was selected in the Northeastern Black Sea Region of Turkey where landslides are the most effective natural hazard. Movements were determined with static, kinematic and dynamic geodetic models using geodetic, geologic and geophysical measurements made in the study area. Groundwater levels changes were regarded as causative forces in the formulation of the dynamic model. The dynamic model delivered more detailed information (direction, values, velocity, acceleration of movements) about landslide movements. It is possible to formulate more realistic strategies about prevention of landslides by using this information. As a result, it can be suggested that dynamic geodetic models are more useful in landslide studies. 相似文献
19.
The scopes of this work are to study the mechanisms of load transfer and the deformations of the ground during slurry trenching and concreting in dry sand and to evaluate their effects on service structural loads, wall deflections and ground displacements behind the wall caused by subsequent excavation. A series of three-dimensional finite element analyses was carried out modelling the installation of diaphragm walls consisting of panels of different length. The soil was modelled as either linearly elastic-perfectly plastic or incrementally non-linear (hypoplastic) with elastic strain range. Plane strain analyses of diaphragm walls of identical cross section were also carried out in which wall installation was either modelled or the wall was wished in place (WIP). The analyses predict ground movements consistent with the experimental observations both in magnitude and trend. The results also show that the maximum horizontal wall deflections and structural loads reduce with increasing panel aspect ratio towards a minimum which is about twice the value computed for WIP analyses. Panel aspect ratios should be larger than about three to take advantage of the three-dimensional effects. The pattern and magnitude of surface vertical displacements obtained from linearly elastic-perfectly plastic analyses, no matter whether three- or two-dimensional, are unrealistic. 相似文献
20.
Chung Huang Yu-Chang Chan Jyr-Ching Hu Jacques Angelier Jian-Cheng Lee 《Journal of Structural Geology》2008,30(9):1167-1176
The northern segment of the Chelungpu Fault shows an unusually large co-seismic displacement from the event of the Mw 7.6 Chi-Chi earthquake in western Taiwan. Part of the northern segment near the Fengyuan City provides an excellent opportunity for characterizing active thrust-related structures due to a dense geodetic-benchmark network. We reproduced co-seismic deformation patterns of a small segment of this Chelungpu Fault using 924 geodetic benchmarks. According to the estimated displacement vectors, we identified secondary deformations, such as local rigid-block rotation and significant shortening within the hanging wall. The data set also allows us to determine accurately a 3D model of the thrust fault geometry in the shallow subsurface by assuming simple relations between the fault slip, and the horizontal and vertical displacements at the surface. The predicted thrust geometry is in good agreement with borehole data derived from two drilling sites close to the study area. The successful prediction supports our assumptions of rigid displacement and control of displacement in the hanging wall by the fault geometry being useful first approximations. 相似文献