Recent developments in sensor technologies such as Global Navigation Satellite Systems (GNSS), Inertial Measurement Unit (IMU), Light Detection and Ranging (LiDAR), radar, and camera have led to emerging state-of-the-art autonomous systems, such as driverless vehicles or UAS (Unmanned Airborne Systems) swarms. These technologies necessitate the use of accurate object space information about the physical environment around the platform. This information can be generally provided by the suitable selection of the sensors, including sensor types and capabilities, the number of sensors, and their spatial arrangement. Since all these sensor technologies have different error sources and characteristics, rigorous sensor modeling is needed to eliminate/mitigate errors to obtain an accurate, reliable, and robust integrated solution. Mobile mapping systems are very similar to autonomous vehicles in terms of being able to reconstruct the environment around the platforms. However, they differ a lot in operations and objectives. Mobile mapping vehicles use professional grade sensors, such as geodetic grade GNSS, tactical grade IMU, mobile LiDAR, and metric cameras, and the solution is created in post-processing. In contrast, autonomous vehicles use simple/inexpensive sensors, require real-time operations, and are primarily interested in identifying and tracking moving objects. In this study, the main objective was to assess the performance potential of autonomous vehicle sensor systems to obtain high-definition maps based on only using Velodyne sensor data for creating accurate point clouds. In other words, no other sensor data were considered in this investigation. The results have confirmed that cm-level accuracy can be achieved.

The main goal of this study is to introduce two different approaches (i.e. based on spherical trigonometric formula and using sun qibla time) that can be used to determine the qibla directions of the existing mosques were oriented with...

In recent years, in addition to 2.4 GHz Wi-Fi signals, 5 GHz signals have been introduced making it possible to transmit data at both IEEE 802.11n and 802.11ac standards. Therefore, researchers have increasingly focused on developing indoor positioning applications based on Wi-Fi dual band. This study was conducted in two stages. In the first stage, we investigated the behaviours of 2.4 and 5 GHz Wi-Fi signals by collecting received signal strength (RSS) values from access points and determined the relationship between RSS and distance for each signal frequency using a curve fitting technique. Furthermore, we comparatively analysed signal fluctuations and their effects on positioning accuracy. In the second part of the study, we compared the positioning accuracy of four algorithms; namely, bilateration, trilateration, weighted iterative non-linear least square and extended Kalman filter using 2.4 and 5 GHz Wi-Fi signals. The experimental results revealed that the 5 GHz signals were more stable and had better positioning accuracy than the 2.4 GHz signals. Concerning the positioning algorithms, bilateration had the best positioning accuracy at both frequencies.

North Anatolian Fault (NAF) and its share zone (NAFZ) which starts from Karlıova (Bingöl) the east to Saros Gulf (Aegean Sea) the west is one of the active seismic zone all over the world. Many destructive earthquakes occurred on its trace in the last century. After the 1999 Izmit and Düzce earthquakes, the earth science studies increase on the NAF to better understand mechanism and to monitor the motion of it. Monitoring such motion can be achieved by the instrumental tools or techniques like GPS, InSAR, LIDAR, creep meter, etc. Using GPS measurements in 1990’s, the rate and pole of the anticlockwise rotation of the Anatolian plate relative to Eurasia were accurately determined. The GPS observations also showed that while the NW-SE trending section of the NAF between Karlıova and Vezirköprü has nearly purely strike slip mechanism, the NE-SW trending section of the NAF between Vezirköprü and Bolu has transpressive character. While the fault-parallel velocities have been estimated from just a few GPS vectors available in the region, little is known about the fault-perpendicular component of the regional velocity. The rate of conversion and how it varies along strike are not known due to the sparsely distributed GPS benchmarks in the region. At the same time, the aseismic fault creep determined using InSAR technique has needed to proof and improve by other techniques and tools. For this propose the new project has been started to determine quantitatively the rate of convergence and its variation along the NE-SW trending section/segment of the NAF between Bolu and Çorum by employing a new GPS network. In this study, we discuss the tectonic phenomena on the central part (Bolu-Corum) of the NAFZ and present the first results of the project.Keywords: North Anatolian Fault; Deformation; GPS; Earthquake; Geodesy DOI: 10.17350/HJSE19030000011 Full Text: