IOP Conference Series: Earth and Environmental Science, 2021
Klang Valley is a fast-growing area and its development shall be equivalent with precise measurem... more Klang Valley is a fast-growing area and its development shall be equivalent with precise measurements for a precise vertical reference. Thus, existing vertical reference with 3 centimetres (cm) is inadequate and processed with complicated remove-compute-restore (RCR) procedure. Apart from this, areas such as Klang Valley should better than one (1) centimetre level vertical reference. Meanwhile processing method for vertical reference should be simplified and easy tasking. Because of that, methodology for this study is by employing the least squares modification of Stokes formula with additive corrections (KTH). This approach fully uses anomalies rather than residuals which it is more complicated. At the same time, the additive corrections estimator introduced combining the direct and indirect computations method. Datasets used in this study were refined rigorously prior to the gridding scheme in cross validation, free air anomalies, as well as anomaly correction. The KTHKVGM2020 gra...
In flood modelling process, Digital Elevation Models (DEMs) is a valuable tool in topographic par... more In flood modelling process, Digital Elevation Models (DEMs) is a valuable tool in topographic parameterization of hydrological models. The release of the free-of-charge satellite based DEMs such as SRTM and ASTER prompted the accurate flood modelling process especially to propose flood mitigation in the Perlis region. In this research, the accuracy of SRTM DEM of spatial resolution 1 arc-sec and 3 arc-sec, as well as ASTER DEM are evaluated. The reference levels produced from GNSS observation and Earth Gravitational Model 1996 (EGM96), as well as local mean sea level are used to analyse the vertical accuracy of each GDEMs in Perlis, Malaysia. The total of 38 Benchmark (BM) and Standard Benchmark (SBM) around the Perlis region were observed by GNSS using static method and processed using TOPCON Tool software. A comparison with the local mean sea level height indicated that SRTM 1″ is the much greater absolute vertical accuracy with an RMSE of ±3.752 m and continued by SRTM 3″ and ASTER GDEMs where the obtained accuracy was ±4.100 and ±5.647 m, respectively. Also, by using orthometric height form the GNSS and EGM96 as reference elevation, the obtained accuracy was ±3.220, ±3.597, and ±5.832 m for SRTM 1″, SRTM 3″ and ASTER, respectively. Statistical results have also shown that SRTM 1″ has a good correlation with Hmsl and HGNSS where both correlations values are 0.9925, while the SRTM 3″ and ASTER show the correlation of 0.9873 and 0.9375.
Proceedings of the Second International Conference on the Future of ASEAN (ICoFA) 2017 – Volume 2, 2018
In modeling of geoid model, global digital elevation models (GDEMs) and global geopotential model... more In modeling of geoid model, global digital elevation models (GDEMs) and global geopotential models (GGMs) involve in most part of the geoid computation process. Any errors in GDEMs and GGMs will introduce errors directly in geoid computation. Therefore, this study aims to evaluate the six recent GGMs and new digital elevation model from TanDEM-X, as well as the previously available GDEMs, SRTM GDEMs, over the southern region of Peninsular Malaysia. The evaluation of GDEMs has been performed with the use of high-precision Global Navigation Satellite System (GNSS) and EGM96 as vertical reference consisting of 277 stations. Meanwhile, the evaluation of GGMs is carried out using sixty-two (62) collocated GPS/leveling benchmarks (BMs). Based on the statistical analysis, it is shown that the improvement of DEM from TanDEM-X data is compared to the previously available DEMs, SRTM GDEMs. DEM from TanDEM-X of 30-m arc resolution is much better than TanDEM-X of 12-m arc resolution, as well as SRTM 30m and 90m. Comparison of GGMs with GNSS leveling shows that geoid height from GOCO05c fits well with the local geoid model.
The current evolution of technologies and rapid development has influenced the pipeline construct... more The current evolution of technologies and rapid development has influenced the pipeline construction all over the world. However, this development can be a risk to the surrounding environment, for example pipeline leakage. There are numerous incidents that caused by pipeline leakage, which includes petroleum pipeline leakage. The petroleum pipeline leakage is one of the very serious situations that can lead to the explosion and the worst it can cause disaster to the nearby area and loss of life. There are numerous methods that are used to detect underground pipeline leaks. One of the methods is Ground-Penetrating Radar (GPR). This study investigates the petroleum leakage and its impact to the surrounding soil. The objectives of this study are to determine the physical properties of the contaminated soil and to evaluate the numerical analysis of the electromagnetic wave for petroleum leakage diffusion in sand. The prototype of leakage model has been built for simulating observation. The data have been collected for every hour for 16 h to monitor the petroleum leakage diffusion. The software used to process and extract GPR data is Reflex 2DQuick. Furthermore, the Finite Difference Time Domain (FDTD) method was used for the simulation of the petroleum leakage diffusion by simulating the electromagnetic waves penetrating through different materials. GPR signal modelling and numerical analysis were done in MATGPR software. The result of this study indicates the changes of dielectric constant of sand from 3 to 5.3 when the sand is mixed with petroleum. The increase in dielectric properties of sand is due to its ability to store the electrical energy. Moreover, the result of GPR signal modelling proves that the content of petroleum has disturbed the signal attenuation which is transmitted by the antenna.
The Ground Penetrating Radar (GPR), a geophysical technique that uses non-destructive testing to ... more The Ground Penetrating Radar (GPR), a geophysical technique that uses non-destructive testing to detect objects and structure beneath the soil was a huge contribution in survey and engineering, especially in underground utility. GPR has been used since 1970 and the method is still undergoing upgrade alongside the sophisticated processing software. Nevertheless, soil is the principal medium which interferes with the signal penetration of GPR due to its physical and electrical properties. Thus, a study using soil stratigraphy is a prerequisite to understanding GPR radargram. In this study, a test bed was constructed to simulate different soil layers which consist of existing clay, sand, small stone, and crusher run stone. The GPR instrument with frequencies of 100, 250, 400, 750, and 900 MHz was used to collect the data. The processing was carried out using reflex software for image interpretation and three-dimensional (3D) visualizations. This study is expected to help surveyors in u...
IOP Conference Series: Earth and Environmental Science, 2020
Ground Penetrating Radar (GPR) works as an instrument to look for buried objects whether it is na... more Ground Penetrating Radar (GPR) works as an instrument to look for buried objects whether it is natural or man-made. GPR transmits electromagnetic (EM) wave to the ground by transmitter and the signal reflects back to the receiver. In this study, the soil characteristics were monitored based on various types of pipe underground in order to determine the reflectivity of the EM wave. Two types of pipes; iron and polyvinyl chloride (PVC) pipe were buried in two different types of soil; clay and sand. These simulations were used to monitor which type of pipe will give the most effective reflection of EM wave on that particular type of soil. The study was performed by using multiband frequency GPR of 250MHz, 400MHz, 700MHz and 900MHz. The use of multiband frequency was to identify the most suitable frequency in order to gain the most effective reflection of EM wave. The data was processed by using Reflex2DQuick software. The higher the frequency, the lower the depth penetration, but the b...
The geodetic and geotechnical technique have long history in deformation monitoring. However, the... more The geodetic and geotechnical technique have long history in deformation monitoring. However, the lastfew years, the GPS technique has been display that GPS sensor can be effectively deployed in structural health monitoring or deformation monitoring. With recent advance ...
IOP Conference Series: Earth and Environmental Science, 2021
Klang Valley is a fast-growing area and its development shall be equivalent with precise measurem... more Klang Valley is a fast-growing area and its development shall be equivalent with precise measurements for a precise vertical reference. Thus, existing vertical reference with 3 centimetres (cm) is inadequate and processed with complicated remove-compute-restore (RCR) procedure. Apart from this, areas such as Klang Valley should better than one (1) centimetre level vertical reference. Meanwhile processing method for vertical reference should be simplified and easy tasking. Because of that, methodology for this study is by employing the least squares modification of Stokes formula with additive corrections (KTH). This approach fully uses anomalies rather than residuals which it is more complicated. At the same time, the additive corrections estimator introduced combining the direct and indirect computations method. Datasets used in this study were refined rigorously prior to the gridding scheme in cross validation, free air anomalies, as well as anomaly correction. The KTHKVGM2020 gra...
In flood modelling process, Digital Elevation Models (DEMs) is a valuable tool in topographic par... more In flood modelling process, Digital Elevation Models (DEMs) is a valuable tool in topographic parameterization of hydrological models. The release of the free-of-charge satellite based DEMs such as SRTM and ASTER prompted the accurate flood modelling process especially to propose flood mitigation in the Perlis region. In this research, the accuracy of SRTM DEM of spatial resolution 1 arc-sec and 3 arc-sec, as well as ASTER DEM are evaluated. The reference levels produced from GNSS observation and Earth Gravitational Model 1996 (EGM96), as well as local mean sea level are used to analyse the vertical accuracy of each GDEMs in Perlis, Malaysia. The total of 38 Benchmark (BM) and Standard Benchmark (SBM) around the Perlis region were observed by GNSS using static method and processed using TOPCON Tool software. A comparison with the local mean sea level height indicated that SRTM 1″ is the much greater absolute vertical accuracy with an RMSE of ±3.752 m and continued by SRTM 3″ and ASTER GDEMs where the obtained accuracy was ±4.100 and ±5.647 m, respectively. Also, by using orthometric height form the GNSS and EGM96 as reference elevation, the obtained accuracy was ±3.220, ±3.597, and ±5.832 m for SRTM 1″, SRTM 3″ and ASTER, respectively. Statistical results have also shown that SRTM 1″ has a good correlation with Hmsl and HGNSS where both correlations values are 0.9925, while the SRTM 3″ and ASTER show the correlation of 0.9873 and 0.9375.
Proceedings of the Second International Conference on the Future of ASEAN (ICoFA) 2017 – Volume 2, 2018
In modeling of geoid model, global digital elevation models (GDEMs) and global geopotential model... more In modeling of geoid model, global digital elevation models (GDEMs) and global geopotential models (GGMs) involve in most part of the geoid computation process. Any errors in GDEMs and GGMs will introduce errors directly in geoid computation. Therefore, this study aims to evaluate the six recent GGMs and new digital elevation model from TanDEM-X, as well as the previously available GDEMs, SRTM GDEMs, over the southern region of Peninsular Malaysia. The evaluation of GDEMs has been performed with the use of high-precision Global Navigation Satellite System (GNSS) and EGM96 as vertical reference consisting of 277 stations. Meanwhile, the evaluation of GGMs is carried out using sixty-two (62) collocated GPS/leveling benchmarks (BMs). Based on the statistical analysis, it is shown that the improvement of DEM from TanDEM-X data is compared to the previously available DEMs, SRTM GDEMs. DEM from TanDEM-X of 30-m arc resolution is much better than TanDEM-X of 12-m arc resolution, as well as SRTM 30m and 90m. Comparison of GGMs with GNSS leveling shows that geoid height from GOCO05c fits well with the local geoid model.
The current evolution of technologies and rapid development has influenced the pipeline construct... more The current evolution of technologies and rapid development has influenced the pipeline construction all over the world. However, this development can be a risk to the surrounding environment, for example pipeline leakage. There are numerous incidents that caused by pipeline leakage, which includes petroleum pipeline leakage. The petroleum pipeline leakage is one of the very serious situations that can lead to the explosion and the worst it can cause disaster to the nearby area and loss of life. There are numerous methods that are used to detect underground pipeline leaks. One of the methods is Ground-Penetrating Radar (GPR). This study investigates the petroleum leakage and its impact to the surrounding soil. The objectives of this study are to determine the physical properties of the contaminated soil and to evaluate the numerical analysis of the electromagnetic wave for petroleum leakage diffusion in sand. The prototype of leakage model has been built for simulating observation. The data have been collected for every hour for 16 h to monitor the petroleum leakage diffusion. The software used to process and extract GPR data is Reflex 2DQuick. Furthermore, the Finite Difference Time Domain (FDTD) method was used for the simulation of the petroleum leakage diffusion by simulating the electromagnetic waves penetrating through different materials. GPR signal modelling and numerical analysis were done in MATGPR software. The result of this study indicates the changes of dielectric constant of sand from 3 to 5.3 when the sand is mixed with petroleum. The increase in dielectric properties of sand is due to its ability to store the electrical energy. Moreover, the result of GPR signal modelling proves that the content of petroleum has disturbed the signal attenuation which is transmitted by the antenna.
The Ground Penetrating Radar (GPR), a geophysical technique that uses non-destructive testing to ... more The Ground Penetrating Radar (GPR), a geophysical technique that uses non-destructive testing to detect objects and structure beneath the soil was a huge contribution in survey and engineering, especially in underground utility. GPR has been used since 1970 and the method is still undergoing upgrade alongside the sophisticated processing software. Nevertheless, soil is the principal medium which interferes with the signal penetration of GPR due to its physical and electrical properties. Thus, a study using soil stratigraphy is a prerequisite to understanding GPR radargram. In this study, a test bed was constructed to simulate different soil layers which consist of existing clay, sand, small stone, and crusher run stone. The GPR instrument with frequencies of 100, 250, 400, 750, and 900 MHz was used to collect the data. The processing was carried out using reflex software for image interpretation and three-dimensional (3D) visualizations. This study is expected to help surveyors in u...
IOP Conference Series: Earth and Environmental Science, 2020
Ground Penetrating Radar (GPR) works as an instrument to look for buried objects whether it is na... more Ground Penetrating Radar (GPR) works as an instrument to look for buried objects whether it is natural or man-made. GPR transmits electromagnetic (EM) wave to the ground by transmitter and the signal reflects back to the receiver. In this study, the soil characteristics were monitored based on various types of pipe underground in order to determine the reflectivity of the EM wave. Two types of pipes; iron and polyvinyl chloride (PVC) pipe were buried in two different types of soil; clay and sand. These simulations were used to monitor which type of pipe will give the most effective reflection of EM wave on that particular type of soil. The study was performed by using multiband frequency GPR of 250MHz, 400MHz, 700MHz and 900MHz. The use of multiband frequency was to identify the most suitable frequency in order to gain the most effective reflection of EM wave. The data was processed by using Reflex2DQuick software. The higher the frequency, the lower the depth penetration, but the b...
The geodetic and geotechnical technique have long history in deformation monitoring. However, the... more The geodetic and geotechnical technique have long history in deformation monitoring. However, the lastfew years, the GPS technique has been display that GPS sensor can be effectively deployed in structural health monitoring or deformation monitoring. With recent advance ...
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