Hüseyin Pehlivan - Academia.edu (original) (raw)
Uploads
Papers by Hüseyin Pehlivan
Observing the normal oscillations and the behaviours of high-engineeringstructures has become alm... more Observing the normal oscillations and the behaviours of high-engineeringstructures has become almost a necessity in terms of construction security andhuman health. For this purpose, an real-time kinematic GPS (NovAtel 400) and atilt sensor (Leica Nivel20) were installed in a TV tower (220 m high) located inIstanbul, Turkey. The observation serials were recorded over a period of 9 days.All data-sets inXandYdirections were examined in the time domain and wereanalyzed using FFT€. The dominant frequency values (significant frequencies)were determined by comparing at the high- and low-frequency values. Thesedominant frequencies showed that the tower made 4- and 6-second short-periodoscillations and 24- and 12-hour long-period oscillations. All the observationsignals were re-created by the significant low-frequency values using the inverseFourier transform. Thus, the motion model of the tower was determined over9 days. In this study, the 24-hour and 12-hour periodic oscillations were definedthat represent the behaviour of the tower in relation to the effect of the sun’sradiation and the temperature changes
Structural Engineering and Mechanics, Jun 25, 2016
In the last few years, many structural monitoring studies have been performed using different tec... more In the last few years, many structural monitoring studies have been performed using different techniques to measure structures of different scales such as buildings, dams or bridges. One of the mostly used tools are GPS instruments, which have been utilized in various combinations with accelerometers and some other conventional sensors. In the current study, observation series were recorded for 8 hours with GPS receivers (NovAtel) and Inclination Measurement Sensors mounted on a television tower in Istanbul, Turkey. Each series of observations collected from two different sensors were transformed into a single coordinate system (Local Topocentric Coordinates System). The positional changes of the tower were calculated from the GPS and the inclination data. These changes were plotted in two dimensions (2D) on the same graphic. Thus, the possibility of comparison and analysis were found using the data from both the GPS and the Inclinometer complement each other, in the real test area. The positional changes of the tower were modeled for further examination. As a result, the movement of the tower within an area of 1x1 cm2 was observed. Based on the results, it can be concluded that inclinometers can be used for monitoring the structural behavior of the tower.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
Smartphones capable of receiving Global Navigation Satellite Systems (GNSS) signals and location-... more Smartphones capable of receiving Global Navigation Satellite Systems (GNSS) signals and location-based mobile applications have been finding new usage areas day by day. The most popular mobile applications have become a part of our life in many ways, especially in spatial data collection, logistics, sports activities, routing, navigation, information exchange, shopping, emergencies and entertainment. The location-based feature has been the characteristic of the apps realized in real-time or near real-time. Within the scope of this study, a mobile application that can be used on smartphones with the Android operating system and is designed to save time and location information during the desired time and sampling interval and send it to the desired e-mail address is presented. The development stages of this location-based mobile application developed using open-source codes and its use on smartphones were shown. The usage areas of the application and a realized test study were explained.
Structural Engineering and Mechanics, 2018
In this study, low-and high-frequency structure behaviors were identified and a systematic analys... more In this study, low-and high-frequency structure behaviors were identified and a systematic analysis procedure was proposed using noisy GPS data from a 165-m-high tower in İstanbul, Turkey. The raw GPS data contained long-and shortperiodic position changes and noisy signals at different frequencies. To extract the significant results from this complex dataset, the general structure and components of the GPS signal were modeled and analyzed in the time and frequency domains. Uncontrolled jumps and deviations involving the signal in the time domain were pre-filtered. Then, the signal was converted to the frequency domain after applying low-and high-pass filters, and the frequency and periodic component values were calculated. The spectrum of the tower motion obtained from the filtered GPS data had dominant peaks at a low frequency of 1.15572×10-4 Hz and a high frequency of 0.16624 Hz, consistent with two equivalent GPS datasets. Then, the signal was reconstructed using inverse Fourier transform with the dominant low frequency values to obtain filtered and interpretable clean signals. With the proposed sequence, processing of noisy data collected from the GPS receivers mounted very close to the structure is effective in revealing the basic behaviors and features of buildings.
International Journal of Engineering and Geosciences, 2019
In recent years, the continuously operating reference station – Turkey (CORS-TR) system has been ... more In recent years, the continuously operating reference station – Turkey (CORS-TR) system has been widely used in engineering and cadastral work in Turkey due to ease of use, low cost, and national legislative requirements. In this study, long-term Network RTK (Real-time Kinematic) data were collected under 10°, 20°, 30° and 40° satellite views using a different approach from previous work. In order to evaluate the positioning performance of the system, the measurements were undertaken at different elevation angles (open, partially blocked and extremely blocked) and by considering three different correction techniques (FKP, VRS and MAC), and the results were evaluated in terms of repeatability. From the analysis of the data, it was understood that the performances of the three correction techniques were generally similar, and even in the case of a limited satellite view, the errors remained below 7 cm in all three techniques. However, when the 2D and 3D components were analyzed togeth...
Erzincan Üniversitesi Fen Bilimleri Enstitüsü Dergisi, 2019
Bu çalışmada, yapıların bağıl deplasmanlarının belirlenmesinde, Robotik Total Station (RTS) ve Gl... more Bu çalışmada, yapıların bağıl deplasmanlarının belirlenmesinde, Robotik Total Station (RTS) ve Global Navigation Satellite System (GNSS) ölçümlerinin kullanılabilirliği araştırılmış ve deneysel verilerle analiz edilmiştir. Bu amaçla, İstanbul'da bulunan yüksek bir yapının gözlemlenebilir yükseklikte tepesine, iki adet GNSS alıcı anteni ve Total Station prisma reflektörleri monte edilmiştir. Bu iki gözlem noktasında, Gerçek Zamanlı GNSS ölçümleri ve yaklaşık 520 m uzaklıkta bulunan izleme noktalarından iki adet RTS kullanılarak açı-mesafe-zenit öçümleri, eş zamanlı olarak gerçekleştirilmiştir. Böylece, kayıt edilen bu gözlem serileri analiz edilerek yapının salınım genliklerinin belirlenmesi ve karşılaştırılması hedeflenmiştir. Analiz sonucunda şu sonuçlar elde edilmiştir; GNSS ölçümleri ile centimeter doğrulukla 0.5-1 cm genlikli salınımlar belirlemek mümkün olmuşken, RTS ölçümleri ile birkaç mm doğrulukla (2 mm) genlikli salınımlar kayıt edilebilmiş ancak yüksek frekanslı yerde...
Monitoring large structures is a significant issue involving public health on which new studies a... more Monitoring large structures is a significant issue involving public health on which new studies are constantly carried out. Although the Global Navigation Satellite System (GNSS) is the most preferable method for measuring structural displacements, total stations, one of the classical geodetic instruments, are the first devices that come to mind in cases that
require complementary usage and auxiliary measurement methods. In this study, the relative displacements of the structural movements of a tower were determined using robotic total stations (RTS) and GNSS. Two GNSS receivers and two RTS observations were carried out simultaneously for 10 hours under normal weather conditions. The spectral analysis of the GNSS data was performed using fast Fourier transform (FFT), and while the dominant modal frequencies were determined, the total station data were balanced with the least-squares technique, and the position and position errors were calculated for each measurement epoch. It has been observed that low-frequency structural movements can be determined by both methods. This result shows that total station measurements are a helpful alternative method for monitoring large structures in situations where measurements are not possible due to the basic handicaps of GNSS or where it is necessary to determine displacements with short observations.
In this study, low-and high-frequency structure behaviors were identified and a systematic analys... more In this study, low-and high-frequency structure behaviors were identified and a systematic analysis procedure was proposed using noisy GPS data from a 165-m-high tower in İstanbul, Turkey. The raw GPS data contained long-and shortperiodic position changes and noisy signals at different frequencies. To extract the significant results from this complex dataset, the general structure and components of the GPS signal were modeled and analyzed in the time and frequency domains. Uncontrolled jumps and deviations involving the signal in the time domain were pre-filtered. Then, the signal was converted to the frequency domain after applying low-and high-pass filters, and the frequency and periodic component values were calculated. The spectrum of the tower motion obtained from the filtered GPS data had dominant peaks at a low frequency of 1.15572×10-4 Hz and a high frequency of 0.16624 Hz, consistent with two equivalent GPS datasets. Then, the signal was reconstructed using inverse Fourier transform with the dominant low frequency values to obtain filtered and interpretable clean signals. With the proposed sequence, processing of noisy data collected from the GPS receivers mounted very close to the structure is effective in revealing the basic behaviors and features of buildings.
Conference Presentations by Hüseyin Pehlivan
A detection method of mismatched measures in GNSS coordinate time series: Fuzzy logic and IQR (Interquartile Range) based approach, 2023
This study presents a new approach for outlier detection aiming to enhance the accuracy and relia... more This study presents a new approach for outlier detection aiming to enhance the accuracy and reliability of GNSS data. Unlike traditional approaches, this approach combines fuzzy logic and the Interquartile Range (IQR) method to improve outlier detection. The fuzzy logic-based method is employed to flexibly model data characteristics. Individual outlier scores are calculated for each data point using fuzzy logic, and these scores are then utilized to identify outliers in the dataset. By determining a threshold value based on the spread of the data around its center using the IQR method, data points scoring above this threshold can be considered outliers. The combination of these two methods ensures a more reliable and accurate outlier detection. When applying the proposed approach to a test signal containing obvious outlier values, it is observed that the processed time series exhibits a better normal distribution and improves performance metrics, indicating enhanced signal quality. Experimental results demonstrate the effectiveness of the proposed approach in effectively detecting outliers in GNSS coordinate time series. Overall, the proposed approach offers a promising solution for outlier detection in GNSS data by integrating fuzzy logic and the IQR method. It provides improved accuracy and reliability, leading to enhanced data analysis and interpretation in GNSS applications.
Observing the normal oscillations and the behaviours of high-engineeringstructures has become alm... more Observing the normal oscillations and the behaviours of high-engineeringstructures has become almost a necessity in terms of construction security andhuman health. For this purpose, an real-time kinematic GPS (NovAtel 400) and atilt sensor (Leica Nivel20) were installed in a TV tower (220 m high) located inIstanbul, Turkey. The observation serials were recorded over a period of 9 days.All data-sets inXandYdirections were examined in the time domain and wereanalyzed using FFT€. The dominant frequency values (significant frequencies)were determined by comparing at the high- and low-frequency values. Thesedominant frequencies showed that the tower made 4- and 6-second short-periodoscillations and 24- and 12-hour long-period oscillations. All the observationsignals were re-created by the significant low-frequency values using the inverseFourier transform. Thus, the motion model of the tower was determined over9 days. In this study, the 24-hour and 12-hour periodic oscillations were definedthat represent the behaviour of the tower in relation to the effect of the sun’sradiation and the temperature changes
Structural Engineering and Mechanics, Jun 25, 2016
In the last few years, many structural monitoring studies have been performed using different tec... more In the last few years, many structural monitoring studies have been performed using different techniques to measure structures of different scales such as buildings, dams or bridges. One of the mostly used tools are GPS instruments, which have been utilized in various combinations with accelerometers and some other conventional sensors. In the current study, observation series were recorded for 8 hours with GPS receivers (NovAtel) and Inclination Measurement Sensors mounted on a television tower in Istanbul, Turkey. Each series of observations collected from two different sensors were transformed into a single coordinate system (Local Topocentric Coordinates System). The positional changes of the tower were calculated from the GPS and the inclination data. These changes were plotted in two dimensions (2D) on the same graphic. Thus, the possibility of comparison and analysis were found using the data from both the GPS and the Inclinometer complement each other, in the real test area. The positional changes of the tower were modeled for further examination. As a result, the movement of the tower within an area of 1x1 cm2 was observed. Based on the results, it can be concluded that inclinometers can be used for monitoring the structural behavior of the tower.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
Smartphones capable of receiving Global Navigation Satellite Systems (GNSS) signals and location-... more Smartphones capable of receiving Global Navigation Satellite Systems (GNSS) signals and location-based mobile applications have been finding new usage areas day by day. The most popular mobile applications have become a part of our life in many ways, especially in spatial data collection, logistics, sports activities, routing, navigation, information exchange, shopping, emergencies and entertainment. The location-based feature has been the characteristic of the apps realized in real-time or near real-time. Within the scope of this study, a mobile application that can be used on smartphones with the Android operating system and is designed to save time and location information during the desired time and sampling interval and send it to the desired e-mail address is presented. The development stages of this location-based mobile application developed using open-source codes and its use on smartphones were shown. The usage areas of the application and a realized test study were explained.
Structural Engineering and Mechanics, 2018
In this study, low-and high-frequency structure behaviors were identified and a systematic analys... more In this study, low-and high-frequency structure behaviors were identified and a systematic analysis procedure was proposed using noisy GPS data from a 165-m-high tower in İstanbul, Turkey. The raw GPS data contained long-and shortperiodic position changes and noisy signals at different frequencies. To extract the significant results from this complex dataset, the general structure and components of the GPS signal were modeled and analyzed in the time and frequency domains. Uncontrolled jumps and deviations involving the signal in the time domain were pre-filtered. Then, the signal was converted to the frequency domain after applying low-and high-pass filters, and the frequency and periodic component values were calculated. The spectrum of the tower motion obtained from the filtered GPS data had dominant peaks at a low frequency of 1.15572×10-4 Hz and a high frequency of 0.16624 Hz, consistent with two equivalent GPS datasets. Then, the signal was reconstructed using inverse Fourier transform with the dominant low frequency values to obtain filtered and interpretable clean signals. With the proposed sequence, processing of noisy data collected from the GPS receivers mounted very close to the structure is effective in revealing the basic behaviors and features of buildings.
International Journal of Engineering and Geosciences, 2019
In recent years, the continuously operating reference station – Turkey (CORS-TR) system has been ... more In recent years, the continuously operating reference station – Turkey (CORS-TR) system has been widely used in engineering and cadastral work in Turkey due to ease of use, low cost, and national legislative requirements. In this study, long-term Network RTK (Real-time Kinematic) data were collected under 10°, 20°, 30° and 40° satellite views using a different approach from previous work. In order to evaluate the positioning performance of the system, the measurements were undertaken at different elevation angles (open, partially blocked and extremely blocked) and by considering three different correction techniques (FKP, VRS and MAC), and the results were evaluated in terms of repeatability. From the analysis of the data, it was understood that the performances of the three correction techniques were generally similar, and even in the case of a limited satellite view, the errors remained below 7 cm in all three techniques. However, when the 2D and 3D components were analyzed togeth...
Erzincan Üniversitesi Fen Bilimleri Enstitüsü Dergisi, 2019
Bu çalışmada, yapıların bağıl deplasmanlarının belirlenmesinde, Robotik Total Station (RTS) ve Gl... more Bu çalışmada, yapıların bağıl deplasmanlarının belirlenmesinde, Robotik Total Station (RTS) ve Global Navigation Satellite System (GNSS) ölçümlerinin kullanılabilirliği araştırılmış ve deneysel verilerle analiz edilmiştir. Bu amaçla, İstanbul'da bulunan yüksek bir yapının gözlemlenebilir yükseklikte tepesine, iki adet GNSS alıcı anteni ve Total Station prisma reflektörleri monte edilmiştir. Bu iki gözlem noktasında, Gerçek Zamanlı GNSS ölçümleri ve yaklaşık 520 m uzaklıkta bulunan izleme noktalarından iki adet RTS kullanılarak açı-mesafe-zenit öçümleri, eş zamanlı olarak gerçekleştirilmiştir. Böylece, kayıt edilen bu gözlem serileri analiz edilerek yapının salınım genliklerinin belirlenmesi ve karşılaştırılması hedeflenmiştir. Analiz sonucunda şu sonuçlar elde edilmiştir; GNSS ölçümleri ile centimeter doğrulukla 0.5-1 cm genlikli salınımlar belirlemek mümkün olmuşken, RTS ölçümleri ile birkaç mm doğrulukla (2 mm) genlikli salınımlar kayıt edilebilmiş ancak yüksek frekanslı yerde...
Monitoring large structures is a significant issue involving public health on which new studies a... more Monitoring large structures is a significant issue involving public health on which new studies are constantly carried out. Although the Global Navigation Satellite System (GNSS) is the most preferable method for measuring structural displacements, total stations, one of the classical geodetic instruments, are the first devices that come to mind in cases that
require complementary usage and auxiliary measurement methods. In this study, the relative displacements of the structural movements of a tower were determined using robotic total stations (RTS) and GNSS. Two GNSS receivers and two RTS observations were carried out simultaneously for 10 hours under normal weather conditions. The spectral analysis of the GNSS data was performed using fast Fourier transform (FFT), and while the dominant modal frequencies were determined, the total station data were balanced with the least-squares technique, and the position and position errors were calculated for each measurement epoch. It has been observed that low-frequency structural movements can be determined by both methods. This result shows that total station measurements are a helpful alternative method for monitoring large structures in situations where measurements are not possible due to the basic handicaps of GNSS or where it is necessary to determine displacements with short observations.
In this study, low-and high-frequency structure behaviors were identified and a systematic analys... more In this study, low-and high-frequency structure behaviors were identified and a systematic analysis procedure was proposed using noisy GPS data from a 165-m-high tower in İstanbul, Turkey. The raw GPS data contained long-and shortperiodic position changes and noisy signals at different frequencies. To extract the significant results from this complex dataset, the general structure and components of the GPS signal were modeled and analyzed in the time and frequency domains. Uncontrolled jumps and deviations involving the signal in the time domain were pre-filtered. Then, the signal was converted to the frequency domain after applying low-and high-pass filters, and the frequency and periodic component values were calculated. The spectrum of the tower motion obtained from the filtered GPS data had dominant peaks at a low frequency of 1.15572×10-4 Hz and a high frequency of 0.16624 Hz, consistent with two equivalent GPS datasets. Then, the signal was reconstructed using inverse Fourier transform with the dominant low frequency values to obtain filtered and interpretable clean signals. With the proposed sequence, processing of noisy data collected from the GPS receivers mounted very close to the structure is effective in revealing the basic behaviors and features of buildings.
A detection method of mismatched measures in GNSS coordinate time series: Fuzzy logic and IQR (Interquartile Range) based approach, 2023
This study presents a new approach for outlier detection aiming to enhance the accuracy and relia... more This study presents a new approach for outlier detection aiming to enhance the accuracy and reliability of GNSS data. Unlike traditional approaches, this approach combines fuzzy logic and the Interquartile Range (IQR) method to improve outlier detection. The fuzzy logic-based method is employed to flexibly model data characteristics. Individual outlier scores are calculated for each data point using fuzzy logic, and these scores are then utilized to identify outliers in the dataset. By determining a threshold value based on the spread of the data around its center using the IQR method, data points scoring above this threshold can be considered outliers. The combination of these two methods ensures a more reliable and accurate outlier detection. When applying the proposed approach to a test signal containing obvious outlier values, it is observed that the processed time series exhibits a better normal distribution and improves performance metrics, indicating enhanced signal quality. Experimental results demonstrate the effectiveness of the proposed approach in effectively detecting outliers in GNSS coordinate time series. Overall, the proposed approach offers a promising solution for outlier detection in GNSS data by integrating fuzzy logic and the IQR method. It provides improved accuracy and reliability, leading to enhanced data analysis and interpretation in GNSS applications.