Cevat Inal

Preliminary evaluation of precise inclination sensor and GPS for monitoring full-scale dynamic response of a tall reinforced concrete building

Abstract It is necessary to use different sensors in an integrated manner – GPS, accelerometer, inclination sensor and so on – in order to monitor and identify static, quasi-static and resonant response of tall buildings subjected to wind loading. There are some differences among these sensors with respect to data sampling rate, data quality, and their measurement accuracy. Therefore, using different sensors together for a monitoring project is important because of the complementary nature of each sensor. In this study, the behaviour of a tall reinforced concrete building (30 stories high) under wind load has been monitored using GPS and inclination sensors. This paper assesses the dynamic measurement quality and reliability of inclinometers for building monitoring applications, and discusses the strengths and weaknesses of GPS vis-a-vis the use of inclination sensors for monitoring the dynamic response of tall buildings under wind load. Data collected by these sensors have been analysed in the time and frequency domains. It was found that GPS observations were distorted by multipath caused by a reflecting surface on top of the building. From the analyses in the frequency domain, the 1st mode natural frequencies of the building determined from both sensors agree very well with each other. The discrepancy of this measured 1st mode natural frequency compared to that derived from FEM (Finite Element Model) prediction is 7%.

Comparing GLONASS-only with GPS-only and hybrid positioning in various length of baselines

Nowadays, GPS is the best positioning system with its constellation, but number of GLONASS satellites increased to the required number, with launched new ones, for positioning. With recent revitalization of GLONASS, a great number of high precision GLONASS and GPS/GLONASS receivers have been produced. In this paper, baselines of two networks have been analyzed in order to assess the usability of GLONASS on global positioning. In both networks, repeatabilities of results were investigated by using GPS, GLONASS and GPS/GLONASS data. Results revealed that repeatabilities of all baselines by using GLONASS observations are not consistent when compared to the GPS and GPS/GLONASS.

The Optimal Design of Baseline Configuration in GPS Networks by Using the Particle Swarm Optimisation Algorithm

Abstract The selection of the optimal GPS baselines can be performed by solving the geodetic second-order design (SOD) problem. In this paper, the particle swarm optimisation (PSO) algorithm, a stochastic global optimisation method, has been employed for the selection of the optimal GPS baselines to be measured in the field that will meet the postulated criterion matrix at a reasonable cost. PSO, which is an iterative-heuristic search algorithm in swarm intelligence, emulates collective behavior of bird flocking, fish schooling or bee swarming, to converge to the global optimum. The fundamentals of the algorithm are given. Then, the efficiency and the applicability of the algorithm are demonstrated with an example of GPS network. Our example shows that the PSO is practical because it does not produce negative or greater than maximum achievable weights of available instruments; it is effective because it yields networks that meet the optimisation criteria; and it is reliable because it converges to the global optimum of an objective function. It is also suitable for non-linear matrix functions that very often encountered in geodetic network optimisation.

Use of the particle swarm optimization algorithm for second order design of levelling networks

Abstract The weight problem in geodetic networks can be dealt with as an optimization procedure. This classic problem of geodetic network optimization is also known as second-order design. The basic principles of geodetic network optimization are reviewed. Then the particle swarm optimization (PSO) algorithm is applied to a geodetic levelling network in order to solve the second-order design problem. PSO, which is an iterative-stochastic search algorithm in swarm intelligence, emulates the collective behaviour of bird flocking, fish schooling or bee swarming, to converge probabilistically to the global optimum. Furthermore, it is a powerful method because it is easy to implement and computationally efficient. Second-order design of a geodetic levelling network using PSO yields a practically realizable solution. It is also suitable for non-linear matrix functions that are very often encountered in geodetic network optimization. The fundamentals of the method and a numeric example are given.

Scaling of EDM calibration baselines by GPS and controlling of EDM parameters

Abstract The calibration values of electromagnetic distance measurements, which have been given by their own firms, can lose their currency in time. So, the EDMs must be controlled in the particular time intervals. The EDM controls have been usually made in the EDM calibration baselines, which are constituted for this aim. Zero addition, scale coefficient and phase difference measurement function constitute the measurement function as a result of control done. The EDM calibration baseline must be scaled to determine the scale coefficient. Not only high accuracy instruments as Kern Mekometer 3000 but also GPS can be used for scaling. In this study, it has been investigated that possibility of scaling of EDM calibration baseline by using GPS and the scaled EDM calibration baseline, and the calibration parameters of Sokkisha SET2, Topcon GTS701, Topcon GTS 229 and Sokkia Power SET 2000 electronic tacheometers have also been estimated.

Importance of probability levels for robustness analysis of geodetic networks

Abstract Robustness Analysis is a natural merger of reliability and strain and defined as the ability to resist deformations caused by the maximum undetectable errors. Internal reliability criterion describes maximum undetectable errors in observations, which would not be detected by Baarda’s statistical testing method (data snooping) based on the chosen Type I and II error probabilities. The non-centrality parameter is a function of probability levels and it plays an important role in Robustness Analysis. In this paper, it is aimed to show the impact of non-centrality parameter on the displacements and the relationship between the selected confidence level for confidence regions and threshold values in a geodetic network. For a geodetic network example, a GPS network is chosen and computations of displacements and threshold values (derived from confidence regions) have been carried out for both in-context and out-of context approaches. According to our results, the non-centrality parameter controls the magnitudes of displacements without affecting their relative behaviours. Statistically, lower probability levels are desired. However, if error probabilities are decreased, the non-centrality parameter increases. Since, the non-centrality parameter scales the displacements, a balance between both types of decision error is needed to obtain displacement values that are smaller than threshold values in order to reach a totally robust network at the required level of probability.

Determination of 2011 Van/Turkey earthquake (M = 7.2) effects from measurements of CORS-TR network

Turkey is a country that has active fault lines and is prone to earthquake. The positional variations resulted from the Van earthquake (a magnitude of M = 7.2) on 23 October 2011 and were calculated by using data from CORS-TR (Continuously Operating Reference Station network) stations. The GPS data from the CORS-TR stations effected from the earthquake were evaluated by the BERNESE 5.0 software. For calculating the positional displacements in the CORS-TR stations after the earthquake that occurred in Van, the measurements from 16 International GNSS Service (IGS) stations around Turkey, where their coordinates and velocity vectors were considered to be constant at the ITRF2005 datum. The greatest variation was measured from the Muradiye station, which is the closest point to the epicentre of the earthquake. The variation in this station was −42.7 mm in the vertical direction, −60.3 mm in the northern direction and −18.7 mm in the eastern direction.

COMPARISON OF REGIONAL AND GLOBAL TEC VALUES: TURKEY MODEL

The ionosphere is a layer of atmosphere 60 km to 1,100 km above the earth and is composed of solar rays and ionized gases. The ionosphere is an important layer affecting Global Navigation Satellite System (GNSS) measures. The quality of GNSS measures is directly related to the changes in the ionosphere. For this reason, monitoring changes in the ionosphere is quite important. One of the important parameters expressing the characteristic of the ionosphere is the Total Electron Content (TEC), which is a function of electron density exhibiting transformation with solar radiation. In this study, 68 stations including 56 TUSAGA-Active (CORS-TR) stations and also IGS stations were taken for evaluation. Bernese v5.2 GNSS software developed by Bern University of Switzerland was employed at the evaluation stage. From 2009 until 2015, TEC values were calculated at two hourly intervals, one day for each month. In the study, where a Single Layer Model was used, TEC values obtained from GNSS measurements have been compared with the TEC (IRI-2012 TEC) values obtained from the global ionosphere map (GIM-TEC) and the international ionosphere reference model programme published by the Centre for Orbit Determination in Europe (CODE), the European Space Agency (ESA), and the Jet Propulsion Laboratory (JPL).

Statistical analysis of accuracy and precision of GNSS receivers used in network RTK

It is important to make accurate and precise measurements in surveying applications. The concepts of accuracy and precision are not synonymous, even though they are commonly used in place of each other. Nowadays, real-time kinematic (RTK) method is widely used at surveying. As the RTK method can be done depending on a reference station, in countries which establish Continuously Operating Reference Stations (CORS) Network, method known as Network-RTK (N-RTK) can be done depending on the CORS Network. Continuously Operating Reference Stations-Turkey Network (CORS-TR), which consists of 146 reference stations that allow positioning both real time and post-process, was established in 2009. In this study, accuracy and precision of Global Navigation Satellite Systems (GNSS) receivers are tried to determine depending on different correction techniques. For this purpose, 12-h GNSS observations were performed at SLCK-Turkish National Fundamental GPS Network (SLCK-TNFGN) point. The observations were adjusted based on CORS-TR. N-RTK measurements were performed with different GNSS receivers, and accuracies of the receivers were investigated. In order to determine precisions of the receivers, means of RTK measurements were calculated and precisions of the receivers were determined. As a result of investigation, it is seen that accuracy and precision of receivers at 2D positioning and height vary depending on correction technique.

Surveying and Mapping Using Mobile Phone in Archeological Settlements

Depending on the development of technology, the boundary concept between different disciplines became unclear today and it became necessary to work jointly depending on data sharing. Also Producing the maps is effected the development of the technology and positioning of desired area is become very fast. Today, instead of hand GPS, users can be obtained coordinate desired via programs which are compatible with mobile phone. CORS (Continuously Operation Reference System) GNSS (Global Navigation Satellite System) receivers which measure points coordinates (x, y, h) at all weather conditions, day and night will become compatible Mobil PC devices (Mobil Phone) via compatible software. By means of this study, including the surveys of Ancient History and Archaeology sciences, different samples belonging to different periods have been evaluated. In this study, coordinates obtained with CORS-TR (Continuously Operation Reference SystemTuRkey) and Asus Zenfone 6 in which Kocaman Pro Software was used at selected areas compare with each and the usage of Asus Zenfone 6 was investigated in term of easiness and accuracy in Archaeological Settlements. This study was carried out at the Hatıp Castle, Malas II and Campus ruins in Konya. Only horizontal accuracy (x, y) was investigated. The horizontal accuracy is higher in Malas II and Campus ruins than Hatıp Castle. This is due to the distance of the GSM networks to the application area. Key-words: Map, Coordinates, Measurement, Accuracy, Mobile Phone, Archaeological Settlement.