Türkiye’nin batısında, Kütahya ilinde sphaeridium fabricus, 1775 (coleoptera: hydrophilidae) cinsi üzerine bir çalışma

Coprophilous Hydrophilidae were sampled from June 2010 to May 2011 using baited pitfall traps in 14 localities at different altitudes (469m-1810m) in Kütahya, western Turkey. As a result of the study, a total of 668 samples belonging to 5 species were identified. The identified specimens are Sphaeridium bipustulatum Fabricius, 1781, S. lunatum Fabricius, 1792, S. marginatum Fabricius, 1787, S. scarabaeoides (Linnaeus, 1758) and S. substriatum Faldermann, 1838, among which S. lunatum is recorded from Turkey for the first time. S. bipustulatum and S. marginatum, which made up 80.69% of all collected beetles determined as eudominante. The highest number of specimens was obtained from December to April meaning that the Sphaeridium community in the study area reached its highest number in winter and spring.Türkiye batısında Kütahya’da, Haziran 2010’dan Mayıs 2011’e kadar, 14 lokalitede ve farklı yüksekliklerde (469m1810m) yemli çukur tuzaklar kullanılarak koprofil Hydrophilidae örnekleri toplanmıştır. Çalışma sonucunda toplam 5 türe ait 668 örnek tespit edilmiştir. Toplanan örneklerin Sphaeridium bipustulatum Fabricius, 1781, S. lunatum Fabricius, 1792, S. marginatum Fabricius, 1787, S. scarabaeoides (Linnaeus, 1758) ve S. substriatum Faldermann, 1838 türlerine ait oldukları belirlenmiştir. S. lunatum Türkiye’den ilk kez kayıt edilmiştir. Toplanan böceklerin %80,69'unu oluşturan S. bipustulatum ve S. marginatum en baskın türler olarak belirlenmiştir. Aralık ayından Nisan ayına kadar yoğun örnek elde edilmiş olması, çalışma alanı içerisindeki Sphaeridium popülasyonlarının kış ve ilkbahar döneminde en yüksek birey sayılarına ulaştığını göstermektedir

Evaluation of High-Rate GNSS-PPP for Monitoring Structural Health and Seismogeodesy Applications

This study evaluates the usability of the GNSS-PPP method for structural health monitoring and seismogeodesy applications. Two test scenarios were considered. The first test scenario included monitoring hormonic oscillations in amplitude of 5 mm to 20 mm with the frequency range of 0.2 Hz to 2.5 Hz that were generated using a shaking table, which has the ability to move in one direction in a horizontal plane. The second test scenario was carried out by simulating the El-Centro Earthquake as a seismogeodesy application. The used GNSS data comprised dual-frequency observations with a 10 Hz sampling rate. GNSS-derived positioning time series were obtained by processing the data using a post-mission kinematic PPP method and results were compared, in both the frequency domain and time domain, with LVDT (Linear Variable Differential Transformer) data, taking as a reference. Results show that the high-rate GNSS PPP method can capture the frequencies of harmonic movements comparable to the LVDT. The observed amplitudes of the harmonic oscillations are slightly different from the LVDT data at the order of mm level. These results demonstrate the ability of the high-rate GNSS PPP method to reliably monitor structural and earthquake-induced vibration frequencies and amplitudes for both the structural health and seismogeodesy applications

Investigating the ability of high-rate GNSS-PPP for determining the vibration modes of engineering structures: small scale model experiment

This study evaluates the performance of the Precise Point Positioning method using Global Navigation Satellite System measurements (GNSS-PPP) for monitoring vibration modes of shear type buildings excited by harmonic ground motions and hammer tests. For experimental testing, the shear type lumped-mass building system is represented by a specially designed metal frame model, resembling a three story building, which was excited on a small scale shaking table. The excitation protocols applied were harmonic motions with different frequencies and amplitudes. The metal model has special deformation plates at the column tips to prevent the nonlinear rotations and out-of-plane motions for the entire system. The fundamental vibration periods of the model structure were computed by a Finite Element Mathematical (FEM) model, which were compared with the position variations determined by GNSS-PPP. Two GNSS receivers were mounted on top of the model structure on the line perpendicular to the motion axis to measure the rotation motion. The GNSS data comprised dual-frequency observations with a 10 Hz sampling rate. GNSS-derived positioning was obtained by processing the data using a post-mission kinematic PPP method with fixed phase ambiguities. Analysis of the characteristics of the vibration frequencies showed that the high-rate GNSS PPP method can capture the frequencies of first motion mode of shear type structural response when compared with the FEM output. Results demonstrate the efficiency of the high-rate GNSS PPP method in monitoring first motion mode of a natural frequency

Investigating Performance of High-Rate GNSS-PPP and PPP-AR for Structural Health Monitoring: Dynamic Tests on Shake Table

© 2020 American Society of Civil Engineers. This paper investigates the usability of Global Navigation Satellite System (GNSS) Precise Point Positioning (PPP) methods, traditional PPP with a float-ambiguity solution and with ambiguity resolution (PPP-AR), in structural health monitoring applications based on experimental tests using a single-axis shake table. To evaluate the performance of the PPP methodologies, harmonic oscillations of the motion table with amplitudes ranging from 5 to 10 mm and frequency between 0.1 and 3 Hz were generated representing a wide range of possible structural motions. In addition, ground motion similar to those experienced during a real earthquake, the 1995 Kobe earthquake, and step motions were generated on the shake table. GNSS PPP-derived positioning results at 20 Hz were compared, in both of the frequency and time domains, with reference data comprising LVDT data and relative positioning data. Results show that both PPP methods' measurements can be used in the computation of harmonic oscillation frequencies compared to the LVDT and relative positioning values. The observed amplitudes of the harmonic oscillations are slightly different from the LVDT values on the order of millimeters. The results of a step motion experiment demonstrated that PPP-AR is better than traditional PPP in exhibiting quasi-static or static displacement. Moreover, the capabilities of traditional PPP and PPP-AR methods are evaluated with respect to the natural frequency of a small-scale structural model excited on the shake table. The frequency spectrum of this small-scale structural model derived from the PPP methods is consistent with finite-element model (FEM)-predicted values and relative positioning. The research presented here demonstrates the potential of the high-rate GNSS PPP and PPP-AR methods to reliably monitor structural and earthquake-induced vibration frequencies and amplitudes for both structural and seismological applications. Specifically, all results reveal that high-rate PPP-AR is more accurate than traditional PPP for both dynamic and static displacement detection

Hybrid Wavelet and Principal Component Analyses Approach for Extracting Dynamic Motion Characteristics from Displacement Series Derived from Multipath-Affected High-Rate GNSS Observations

Nowadays, the high rate GNSS (Global Navigation Satellite Systems) positioning methods are widely used as a complementary tool to other geotechnical sensors, such as accelerometers, seismometers, and inertial measurement units (IMU), to evaluate dynamic displacement responses of engineering structures. However, the most common problem in structural health monitoring (SHM) using GNSS is the presence of surrounding structures that cause multipath errors in GNSS observations. Skyscrapers and high-rise buildings in metropolitan cities are generally close to each other, and long-span bridges have towers, main cable, and suspender cables. Therefore, multipath error in GNSS observations, which is typically added to the measurement noise, is inevitable while monitoring such flexible engineering structures. Unlike other errors like atmospheric errors, which are mostly reduced or modeled out, multipath errors are the largest remaining unmanaged error sources. The high noise levels of high-rate GNSS solutions limit their structural monitoring application for detecting load-induced semi-static and dynamic displacements. This study investigates the estimation of accurate dynamic characteristics (frequency and amplitude) of structural or seismic motions derived from multipath-affected high-rate GNSS observations. To this end, a novel hybrid model using both wavelet-based multiscale principal component analysis (MSPCA) and wavelet transform (MSPCAW) is designed to extract the amplitude and frequency of both GNSS relative- and PPP- (Precise Point Positioning) derived displacement motions. To evaluate the method, a shaking table with a GNSS receiver attached to it, collecting 10 Hz data, was set up close to a building. The table was used to generate various amplitudes and frequencies of harmonic motions. In addition, 50-Hz linear variable differential transformer (LVDT) observations were collected to verify the MSMPCAW model by comparing their results. The results showed that the MSPCAW could be efficiently used to extract the dynamic characteristics of noisy dynamic movements under seismic loads. Furthermore, the dynamic behavior of seismic motions can be extracted accurately using GNSS-PPP, and its dominant frequency equals that extracted by LVDT and relative GNSS positioning method. Its accuracy in determining the amplitude approaches 91.5% relative to the LVDT observations

Investigation of real-time GNSS VADASE approach capability of capturing vertical dynamic movements

Yeryüzünde meydana gelen dinamik hareketlerin tespit edilmesinde GNSS (Global Navigation Satellite System) sensörüne dayalı birçok konum belirleme yöntemi (Bağıl Kinematik, Gerçek Zamanlı Kinematik (RTK), Hassas Nokta Konumlama (PPP), Gerçek Zamanlı (RT)-PPP vb.) kullanılmıştır. Kullanılan bu yöntemler ikinci bir GNSS alıcısı, internet bağlantısı, uydu yörünge ve saat düzeltme bilgisi gibi harici parametreler gerektirir. Bu çalışmada herhangi bir harici parametreye ihtiyaç duymadan gerçek zamanlı (Real-Time) dinamik hareketleri doğrudan yakalayabilen VADASE (Variometric Approach for Displacement Analysis Stand-Alone Engine) yaklaşımının düşey yönlü dinamik davranışları belirleyebilme yeteneği incelenmiştir. Çoklu-GNSS gözlemlerine dayalı bu yöntem, zaman ve frekans alanında bağıl konum belirleme (RP) yöntemi referans alınarak PPP yöntemi ile karşılaştırılmıştır. Sonuçlara bakıldığında düşey dinamik hareketlerin baskın frekans değerlerinin üç yöntem için de aynı olduğu görülmüştür. Baskın frekansa karşılık gelen genlik değerlerinde ise deneylerde referans alınan RP yöntemine göre RT-VADASE yönteminde 1.6 mm ila 3.2 mm arasında değişmekteyken PPP yönteminde bu farklılık 1.1 mm ila 1.6 mm arasında değişmektedir. Ayrıca zaman alanında tüm deney durumlarına incelendiğinde RT-VADASE yönteminin PP-PPP yöntemine göre KOH değerleri arasında milimetre düzeyinde (1-2mm) küçük farklılık bulunmaktadır. Sonuçlar, RT-VADASE yaklaşımının anlık olarak düşey dinamik hareketleri doğru ve güvenilir bir şekilde tespit edebileceğini göstermektedir. Bununla birlikte, RT-VADASE yöntemi deprem, rüzgâr, trafik yükü gibi dinamik yüklerin, yapıda meydana getirebileceği etkiyi anlık olarak tespit etmek ve yapı sağlığını tehdit edebilecek durumlarda yapının hızlı tehlike değerlendirilmesi yapılarak insan hayatını tehlikeye düşürecek durumlarda erken uyarı sistemine entegre bir sensör olarak kullanılabileceği gösterilmiştir.Many positioning methods (Relative Kinematic, Real Time Kinematic (RTK), Pricese Point Positioning (PPP) and Real Time (RT)-PPP etc.) based on GNSS sensor have been used to detect dynamic motions occurring on the earth. These methods used require external parameters such as a second GNSS receiver, internet connection, satellite orbit and clock correction information. In this study, the VADASE (Variometric Approach for Displacement Analysis Stand-Alone Engine) approach, which can directly capture dynamic motions in real-time without the need for any additional parameters, are examined. This method, based on multi-GNSS observations, was compared with the PPP method, with reference to the Relative Positioning(RP) method in the time and frequency domain. According to the results, it was seen that the dominant frequency values of vertical dynamic motions were the same for all three methods. While the amplitude values corresponding to the dominant frequency vary between 1.6 mm and 3.2 mm in the RT-VADASE method according to the RP method referenced in the experiments, this difference varies between 1.1 mm and 1.6 mm in the PPP method. In addition, when all experimental cases are examined in the time domain, there is a small (1-2mm) difference between the KOH values of the RT-VADASE method compared to the PP-PPP method. The results show that the RT-VADASE approach can accurately and reliably detect instantaneous vertical dynamic motions. However, it has been shown that the RT-VADASE method can be used as an integrated sensor in the early warning system in situations that will endanger human life by making a rapid hazard assessment of the structure in cases that may threaten the health of the structure, instantly detecting the effect of dynamic loads such as earthquake, wind, traffic load

The positioning performance of low-cost GNSS receivers in the Precise Point Positioning method

Satellite-based positioning, which started being developed in the mid-1960s for military purposes, is now used in almost every area. For the studies single and/or double frequency receivers are used. The cost of a receiver and antenna couple that have capable of high coordinate accuracies ranges from $3000 to$15000. With the production of Original Equipment Manufacturer (OEM) receivers, the cost of satellite-based location determination decreases to approximately one in 10 for the civilian user compared to the operations performed with geodetic receivers and antennas. However, although these receivers collect data in multi-Global Navigation Satellite System (GNSS) and frequencies, the accuracy of the coordinate values estimated is not as high as geodetic receivers and antennas. Therefore, it is necessary to carry out an accuracy study to obtain information about which studies can be used in. In this study, measurements were made at the UZEL point located on the roof of the Yıldız Technical University Geomatics Engineering Department by using the ZED-F9P-02B OEM multi GNSS receiver and ANN-MB L1/L2 multi-band GNSS patch antenna. The performance of the test results has been examined by comparing the results from CSRS(Canadian Spatial Reference System)-PPP with the coordinates of the UZEL point. As a result of the comparison, the difference between the coordinate determined with collected 3.5 hr data and the coordinates of the UZEL point has been determined as – 1.4 cm, 2.8 cm, and 9.3 cm in the East, North, and Height directions, respectivel

Investigating the effects of ultra-rapid, rapid vs. Final precise orbit and clock products on high-rate GNSS-PPP for capturing dynamic displacements

Copyright © 2020 Techno-Press, Ltd. The use of final IGS precise orbit and clock products for high-rate GNSS-PPP proved its effectiveness in capturing dynamic displacement of engineering structures caused by earthquakes. However, the main drawback of using the final products is that they are available after approximately two weeks of data collection, which is not suitable for timely measures after an event. In this study, the use of ultra-rapid products (observed part), which are available after a few hours of data collection, and rapid products, which are available in less than 24 hrs, are investigated and their results are compared to the more precise final products. The tests are designed such that harmonic oscillations with different frequencies and amplitudes and ground motion of a simulated real earthquake are generated using a single axis shake table and the PPP was used to capture these movements by monitoring time-change of the table positions. To evaluate the accuracy of PPP using ultra-rapid, rapid and final products, their results were compared with relative GNSS positioning and LVDT (Linear Variable Differential Transformer) data, treated as reference. The results show that the high-rate GNSS-PPP solutions based on the three products can capture frequencies of harmonic oscillations and dynamic displacement with good accuracy. There were slight differences between ultra-rapid, rapid and final products, where some of the tested events indicated that the latter two produced are more accurate and provide better results compared to the ultra-rapid product for monitoring short-term dynamic displacements

Evaluation of the high-rate GNSS-PPP method for vertical structural motion

© 2018, © 2018 Survey Review Ltd. This study aims at the investigation of GNSS-PP method to determine the dynamic characteristics of structures. Cantilever steel bars having lengths of 70, 100 and 120 cm were tested under dynamic excitation. The GNSS was used to measure the natural frequencies and damping values of all the tested cantilever structures. The GNSS data were processed using relative GNSS positioning and PPP methods. The results obtained using these two methods were also compared with the dynamic characteristics obtained by applying the theoretical and finite element (FE) methods. Furthermore, it is investigated the impact of the stable data length before oscillation events on kinematic PPP. The study showed that the maximum difference among the experimental results in terms of natural frequencies proceeded using PPP is 0.08 Hz when compared with the theoretical and FE results. Furthermore, there is no difference between the PPP and relative GNSS positioning in determining the dynamic behaviour of structures eventhough roving GNSS antenna remains motionless for short-time, such as a few-minutes, before an event occurred

High-rate real-time PPP for dynamic motion detection in vertical direction

[EN] Nowadays, with the developments in GNSS (Global Navigation Satellite System) technology, the data storage and data processing capacity of GPS (Global Positioning System) receivers has been gradually increased. This situation is widely used in the detection and monitoring of horizontal and vertical vibrations that occur in the structure when high temporal resolution geodetic GPS receivers are under the influence of dynamic loads such as earth crust motions, wind load, traffic load, which affect man-made engineering structures. In the study, RT DF-PPP (Real Time Dual Frequency-Precise Point Positioning) method was applied together with a GPS sensor with a sampling interval of 20 Hz, using a steel bar mounted on a steel tree model designed as a structure model, and a steel bar on which different sensors can be integrated and can provide simulation of vertical motions in detecting vertical motions occurring in structures. To evaluate the performance of the method used and to test the performance of capturing vertical displacements, the DF-RP (Dual Frequency-Relative Positioning) method was taken as reference and the results were compared with the PP-PPP (Post Process-PPP) method using the IGS-Final (International GNSS Service-Final) product. When the results are compared with the RP and PP-PPP solutions in the frequency domain of vertical motions as a result of harmonic oscillations of the high-rate RT-PPP method, it has been seen that the amplitudes and frequencies are compatible with each other. Therefore, dynamic motions that occur as a result of natural events such as earthquakes, tsunamis, landslides and volcanic eruptions can be instantly and reliably monitored and detected by the high-rate RT-PPP method. When the results were evaluated in the time domain, an improvement was observed in the RMSE (Root Mean Square Error) and maximum values of RT-PPP and PP-PPP methods according to RP after filtering. When the statistical results are examined, vertical harmonic motions of the solutions made by using both RT-PPP and PP-PPP methods can be detected with accuracy below centimeters. These results clearly show that it can detect vertical dynamic motions in engineering structures such as bridges, skyscrapers and viaducts with RT-PPP method to evaluate. Thus, by detecting the effects of dynamic motions occurring in the structure on the health of the structure, a safe environment will be provided by making a rapid hazard assessment for life safety.Karadeniz, B.; Bezcioglu, M.; Yigit, CO.; Dindar, AA.; Akpinar, B. (2023). High-rate real-time PPP for dynamic motion detection in vertical direction. Editorial Universitat Politècnica de València. 455-460. https://doi.org/10.4995/JISDM2022.2022.1390645546