China
Africa
Explore chapters and articles related to this topic
Creation of “live data” for existing infrastructure
Published in Nigel Powers, Dan M. Frangopol, Riadh Al-Mahaidi, Colin Caprani, Maintenance, Safety, Risk, Management and Life-Cycle Performance of Bridges, 2018
F. R. Gottfredsen, H. Pedersen
Main components of the mobile mapping system are: – Two laser scanners, positioned tilted along driving direction to collect as many objects as possible. Each laser scanner can collect up to 1.016 Mio. points per sec.– One GNSS (Global Navigation Satellite System)/GPS (Global Positioning System), receiving satellite observations for United State satellite system and European satellite system. Satellite observations are stored each second.– One INS (Inertial Navigation System), tracking changes in speed movement together with rotation of the vessel. Data motion is stored twice every second.– Odometer/wheel sensor, tracks the amount of distance travelled by the wheels.– Computer for tracking and storing information.
GPR analysis to detect subsidence: a case study on a loaded reinforced concrete pavement
Published in International Journal of Pavement Engineering, 2022
Mercedes Solla, Norberto Fernández
The GPR data acquisition was conducted with a ProEx system and a 500 MHz centre frequency antenna from the company Malå Geoscience. Five GPR profile lines were acquired around the Hall B (P1 to P5 in Figure 1). The objective was to detect subsidence and possible causes of settlement phenomena. The data acquisition parameters set by the authors were 2 cm of trace-interval distance and a total time window ranging from 65 ns (composed of 450 samples per trace by default) to 90 ns (composed of 616 samples per trace by default). The time window adopted was variable because of the different thickness of anthropic filling used to level the site during construction and, consequently, the number of samples was adjusted to maintain the same resolution in detection; hence, shorter time window was set for the profile lines close to the façade buildings. A survey wheel (odometer) was used to measure the profile lengths and to control the distance between traces.
Understanding the pioneering techniques in reinforced concrete: the case of Punta Begoña Galleries, Getxo, Spain
Published in Building Research & Information, 2020
Laura Damas Mollá, Maialen Sagarna Aranburu, Jesus A. Uriarte, Arantza Aranburu, Ane Zabaleta, Francisco García-García, Iñaki Antigüedad, Tomás Morales
Three-dimensional (3D) GPR methodologies were used to pinpoint and define the rebars and their thicknesses, in the slab under study. The GPR data was collected using a conventional GPR control unit (GSSI SIR-3000 equipment) and different centre-band frequency antennas. In the case of Punta Begoña, two antennas were used, one of 900 MHz and other of 1500 MHz. The 900 MHz antenna was used to determine the relationships between the slab and other structural elements, with a 20 ns time range; while the 1500 MHz antenna enabled more detailed characterization of the reinforcements, cover and tiles with a 12 ns time range, as this frequency is suitable for depths between 20 and 40 cm (Pérez-Gracia et al., 2008; Viriyametanont, Laurens, Klysz, Balayssac, & Arliguie, 2008). The GPR ground-coupled antennas were placed on a survey cart with an odometer wheel (encoder) to calculate trace-interval distance by means of the propagation of broadband electromagnetic radiation and to detect reflectors.
GNSS/MIMU tightly coupled integrated with improved multi-state ZUPT/DZUPT constraints for a Land vehicle in GNSS-denied enviroments
Published in International Journal of Image and Data Fusion, 2021
Yipeng Ning, Wengang Sang, Guobiao Yao, Jingxue Bi, Shida Wang
On the whole, there are two main types of schemes for constraint GNSS/INS integrated navigation systems. One kind of the schemes is to construct the filter constraint model with the observation information of other sensors, such as odometer (Li et al. 2014), lidar (Tang et al. 2015), magnetometer (Wang et al. 2018) etc. Such schemes need to be integrated with additional sensors which increase the complexity of the navigation system. The other kind of the schemes is to construct a filter constraint model what is called internal constraint based on the motion characteristics of the vehicle, such as zero velocity update (ZUPT) (Grejner-Brzezinska et al. 2001), nonholonomic constraint (Peng et al. 2012, Guo et al. 2015), dynamic constraint (Yang et al. 2013) etc. Such schemes do not require additional sensors, have lower cost and strong autonomy, but are effective only for the specific motion state of the vehicle. The zero velocity update (ZUPT) technique is a cheap and effective method to restrain the divergence of INS error without any other assisting sensors, has been widely used in urban canyon land vehicle navigation (Wang et al. 2017) and indoor pedestrian navigation (Wang et al. 2015). According to different carrier and different application environment, the zero velocity state detection algorithm is also different, so researchers have proposed the acceleration-moving variance detector (MV), the acceleration-magnitude detector (MAG), the angular rate energy detector (ARE) and generalised likelihood ratio test (GLRT) etc one after another (Skog et al. 2010).