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Öğe Application of Low-Cost GPS Tools and Techniques for Landslide Monitoring: A Review(Jurnal Teknologi, 2014) Etim, E. Eyo; Musa, Tajul Ariffin; Omar, Kamaludin Mohd; Idris, Khairulnizam M.; Bayrak, Temel; Onuigbo, Ifeanyi; Opaluwa, YusufThe main goal of our ongoing research is to design a low-cost continuous monitoring system for landslide investigation using the Reverse RTK (RRTK) technique. The main objectives of this paper are to review the existing Global Positioning System (GPS) tools and techniques used for landslide monitoring, and to propose a novel low-cost landslide monitoring technique using Reverse RTK GPS. A general overview of GPS application in landslide monitoring is presented, followed by a review of GPS deformation monitoring systems and some of the factors used for their categorization. Finally, the concept, principles and advantages of the proposed new landslide monitoring system are discussed.Öğe Global Positioning System Network Reference Control Optimization Using Dilution of Precision Variances in Gidan Kwano Area, Minna, Nigeria(International Journal of Scientific and Engineering Research, 2014) Lazarus, M. Ojigi; Etim, E. Eyo; Bayrak, TemelThe precision of Global Positioning System (GPS) observables depends on the satellite geometry, represented by the Dilution of Precision (DOP) values, and range of errors caused by signal strength, ionospheric delay, tropospheric delay, and satellite clock offset from GPS time, multipath effects, receiver antenna phase shift, etc. One of the ways of assessing the integrity of satellite availability, positional and navigational accuracy of GPS observation is the use of dilution of precision (DOP) during field observations. This study therefore attempts to optimize GPS Network Reference Control in Gidan Kwano area of Minna, Nigeria, using pre-observation planning and post-observation DOP variances, for selecting the optimum reference point within an established survey network, for future observations and control extension in the study area. Twenty-five (25) GPS stations were observed in rapid-static mode with Leica SR20 DGPS Receivers. The estimates of the DOPs (GDOP, PDOP, HDOP, VDOP and TDOP) showed that, post-observation DOPs have mean values of 2.0, 1.8, 1.6, 0.9, and 0.9 for GDOP, PDOP, HDOP, VDOP and TDOP, respectively, which agree with the post-observation DOPs within about 80 -90%. This implies that, the PDOP developed in the pre-observation planning is valid for rapid-static or kinematic surveys in the study area but less valid for a long-duration (30-minutes and above) static survey in the study area. Based on the DOPs variance analysis for each observed network point, control point GPS14 with PDOP and GDOP of 1.4 and 1.5, respectively was adjudged the optimum point as Reference for survey network observations and extension in the study area.Öğe Modelling the relationship between water level and vertical displacements on the Yamula Dam, Turkey(Natural Hazards and Earth System Sciences, 2007) Bayrak, TemelMonitoring deformation pattern of dams is often one of the most effective ways to understand their safety status. The main objective of the study is to find the extent to which rising reservoir level affects the mechanism of deformation of The Yamula Dam under certain change in the reservoir level conditions during to the first filling period. Three different deformation analysis techniques, namely static, kinematic and dynamic, were used to analyze four geodetic monitoring records consisting of vertical displacements of nine object points established on the Dam and six reference points surrounding of it, to see whether the rising reservoir level have a role in the vertical deformations during the first filling period. The largest vertical displacements were in the middle of the dam. There is an apparent linear relationship between the dam subsidence and the reser- voir level. A dynamic deformation model was developed to model this situation. The model infers a causative relationship between the reservoir level and the dam deformations. The analysis of the results determines the degree of the correlation between the change in the reservoir level and the ob- served structural deformation of the dam.Öğe Verifying Pressure of Water on Dams, a Case Study(Sensors, 2008) Bayrak, TemelSensing and monitoring deformation pattern of dams is often one of the most effective ways to understand their safety status. The main objective of the present study is to find the extent to which rising reservoir level affects the mechanism of deformation of the Yamula dam under certain changes in the reservoir level conditions during the first filling period. A new dynamic deformation analysis technique was developed to analyze four geodetic monitoring records consisting of vertical and horizontal displacements of nine object points established on the dam and six reference points surrounding it, to see whether the rising reservoir level is responsible for the vertical and horizontal deformations during the first filling period. The largest displacements were determined in the middle points of the dam construction. There is an apparent linear relationship between the dam subsidence and the reservoir level. The dynamic deformation model was developed to model this situation. The model infers a causative relationship between the reservoir level and the dam deformations. The analysis of the results determines the degree of the correlation between the change in the reservoir level and the observed structural deformation of the dam.
