No abstract

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 yerdeğiştirme değerleri belirlenememiştir. Bu sonuçlar, otomatize edilen Elektronik Totalstation'ların GNSS'e bir alternatif olarak yapı deplasmanlarının belirlenmesinde kullanılabilirliğini göstermiştir.

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 together, VRS technique showed better results than the other two techniques.

Observing the normal oscillations and the behaviours of high-engineering structures has become almost a necessity in terms of construction security and human health. For this purpose, an real-time kinematic GPS (NovAtel 400) and a tilt sensor (Leica Nivel20) were installed in a TV tower (220 m high) located in Istanbul, Turkey. The observation serials were recorded over a period of 9 days. All data-sets in X and Y directions were examined in the time domain and were analyzed using FFT€. The dominant frequency values (significant frequencies) were determined by comparing at the high-and low-frequency values. These dominant frequencies showed that the tower made 4-and 6-second short-period oscillations and 24-and 12-hour long-period oscillations. All the observation signals were re-created by the significant low-frequency values using the inverse Fourier transform. Thus, the motion model of the tower was determined over 9 days. In this study, the 24-hour and 12-hour periodic oscillations were defined that represent the behaviour of the tower in relation to the effect of the sun's radiation and the temperature changes.

Abstract. 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.