scholarly journals Measuring Three-Dimensional Temperature Distributions in Steel–Concrete Composite Slabs Subjected to Fire Using Distributed Fiber Optic Sensors

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5518
Author(s):  
Yi Bao ◽  
Matthew S. Hoehler ◽  
Christopher M. Smith ◽  
Matthew Bundy ◽  
Genda Chen
Keyword(s):  
Fiber Optic ◽  
Three Dimensional ◽  
Thermal Response ◽  
Point Clouds ◽  
Fiber Optic Sensors ◽  
Distributed Sensors ◽  
Temperature Distributions ◽  
Composite Slabs ◽  
Spatially Distributed ◽  
Dense Point

Detailed information about temperature distribution can be important to understand structural behavior in fire. This study develops a method to image three-dimensional temperature distributions in steel–concrete composite slabs using distributed fiber optic sensors. The feasibility of the method is explored using six 1.2 m × 0.9 m steel–concrete composite slabs instrumented with distributed sensors and thermocouples subjected to fire for over 3 h. Dense point clouds of temperature in the slabs were measured using the distributed sensors. The results show that the distributed sensors operated at material temperatures up to 960 °C with acceptable accuracy for many structural fire applications. The measured non-uniform temperature distributions indicate a spatially distributed thermal response in steel–concrete composite slabs, which can only be adequately captured using approaches that provide a high density of through-depth data points.

scholarly journals Estimating tree stem diameters and volume from smartphone photogrammetric point clouds

2019 ◽  
Vol 93 (3) ◽  
pp. 411-429 ◽  
Author(s):  
Maria Immacolata Marzulli ◽  
Pasi Raumonen ◽  
Roberto Greco ◽  
Manuela Persia ◽  
Patrizia Tartarino
Keyword(s):  
Low Cost ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Point Clouds ◽  
Stem Volume ◽  
Forest Plot ◽  
3D Point Clouds ◽  
Dense Point ◽  
Minimum Number ◽  
Scale Point

Abstract Methods for the three-dimensional (3D) reconstruction of forest trees have been suggested for data from active and passive sensors. Laser scanner technologies have become popular in the last few years, despite their high costs. Since the improvements in photogrammetric algorithms (e.g. structure from motion—SfM), photographs have become a new low-cost source of 3D point clouds. In this study, we use images captured by a smartphone camera to calculate dense point clouds of a forest plot using SfM. Eighteen point clouds were produced by changing the densification parameters (Image scale, Point density, Minimum number of matches) in order to investigate their influence on the quality of the point clouds produced. In order to estimate diameter at breast height (d.b.h.) and stem volumes, we developed an automatic method that extracts the stems from the point cloud and then models them with cylinders. The results show that Image scale is the most influential parameter in terms of identifying and extracting trees from the point clouds. The best performance with cylinder modelling from point clouds compared to field data had an RMSE of 1.9 cm and 0.094 m3, for d.b.h. and volume, respectively. Thus, for forest management and planning purposes, it is possible to use our photogrammetric and modelling methods to measure d.b.h., stem volume and possibly other forest inventory metrics, rapidly and without felling trees. The proposed methodology significantly reduces working time in the field, using ‘non-professional’ instruments and automating estimates of dendrometric parameters.

scholarly journals A SMARTPHONE-BASED 3D PIPELINE FOR THE CREATIVE INDUSTRY – THE REPLICATE EU PROJECT

2017 ◽  
Vol XLII-2/W3 ◽  
pp. 535-541 ◽  
Author(s):  
E. Nocerino ◽  
F. Lago ◽  
D. Morabito ◽  
F. Remondino ◽  
L. Porzi ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Point Clouds ◽  
First Year ◽  
Automated Generation ◽  
Dense Point ◽  
Modelling Techniques ◽  
Eu Project ◽  
Selection Of ◽  
Made In

During the last two decades we have witnessed great improvements in ICT hardware and software technologies. Three-dimensional content is starting to become commonplace now in many applications. Although for many years 3D technologies have been used in the generation of assets by researchers and experts, nowadays these tools are starting to become commercially available to every citizen. This is especially the case for smartphones, that are powerful enough and sufficiently widespread to perform a huge variety of activities (e.g. paying, calling, communication, photography, navigation, localization, etc.), including just very recently the possibility of running 3D reconstruction pipelines. The REPLICATE project is tackling this particular issue, and it has an ambitious vision to enable ubiquitous 3D creativity via the development of tools for mobile 3D-assets generation on smartphones/tablets. This article presents the REPLICATE project’s concept and some of the ongoing activities, with particular attention being paid to advances made in the first year of work. Thus the article focuses on the system architecture definition, selection of optimal frames for 3D cloud reconstruction, automated generation of sparse and dense point clouds, mesh modelling techniques and post-processing actions. Experiments so far were concentrated on indoor objects and some simple heritage artefacts, however, in the long term we will be targeting a larger variety of scenarios and communities.

Application of Brillouin Fiber Optic Sensors to Monitor Pipeline Integrity

2004 ◽  
Author(s):  
R. C. Tennyson ◽  
W. D. Morison ◽  
B. Colpitts ◽  
A. Brown
Keyword(s):  
Optical Fibers ◽  
Continuous Monitoring ◽  
Fiber Optic ◽  
Fiber Optic Sensors ◽  
Third Party ◽  
Ground Movement ◽  
Temperature Profiles ◽  
Thermal Anomalies ◽  
Temperature Distributions ◽  
Close Proximity

This paper describes the application of Brillouin fiber optic sensors to monitor pipeline integrity in terms of third party intrusion, leak detection, and ground movement. Brillouin sensors provide a means for continuous monitoring of strain and temperature distributions over distances of about 25km. The optical fibers can be bonded to the pipeline or buried in close proximity to the pipe. Third party intrusion is detected by strain anomalies caused by vehicles or persons in close proximity to the sensor located at some depth below the surface. Leaks from oil or gas pipelines are detected by thermal anomalies in the temperature profiles. Pipeline movement can also be detected using this system for existing and new pipeline installations. Applications include northern pipelines, high consequence areas, river crossings and fault lines.

scholarly journals Review of Fiber Optic Sensors for Structural Fire Engineering

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 877 ◽  
Author(s):  
Yi Bao ◽  
Ying Huang ◽  
Matthew Hoehler ◽  
Genda Chen
Keyword(s):  
High Temperature ◽  
Fiber Optic ◽  
Fiber Optic Sensors ◽  
Distributed Sensors ◽  
Structural Fire ◽  
Fire Engineering ◽  
Key Characteristics ◽  
Light Signals ◽  
Structural Engineers ◽  
Structural Fire Engineering

Reliable and accurate measurements of temperature and strain in structures subjected to fire can be difficult to obtain using traditional sensing technologies based on electrical signals. Fiber optic sensors, which are based on light signals, solve many of the problems of monitoring structures in high temperature environments; however, they present their own challenges. This paper, which is intended for structural engineers new to fiber optic sensors, reviews various fiber optic sensors that have been used to make measurements in structure fires, including the sensing principles, fabrication, key characteristics, and recently-reported applications. Three categories of fiber optic sensors are reviewed: Grating-based sensors, interferometer sensors, and distributed sensors.

scholarly journals Three-dimensional discrete element modelling of rubble masonry structures from dense point clouds

2020 ◽  
Vol 119 ◽  
pp. 103365
Author(s):  
Nicko Kassotakis ◽  
Vasilis Sarhosis ◽  
Belen Riveiro ◽  
Borja Conde ◽  
Antonio Maria D'Altri ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Point Clouds ◽  
Discrete Element ◽  
Discrete Element Modelling ◽  
Masonry Structures ◽  
Element Modelling ◽  
Dense Point

scholarly journals Rail Track Detection and Projection-Based 3D Modeling from UAV Point Cloud

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5220
Author(s):  
Shima Sahebdivani ◽  
Hossein Arefi ◽  
Mehdi Maboudi
Keyword(s):  
3D Modeling ◽  
Point Cloud ◽  
3D Model ◽  
Three Dimensional ◽  
Point Clouds ◽  
Rail Track ◽  
Three Dimensional Modeling ◽  
Railway Industry ◽  
Dense Point ◽  
Uav Images

The expansion of the railway industry has increased the demand for the three-dimensional modeling of railway tracks. Due to the increasing development of UAV technology and its application advantages, in this research, the detection and 3D modeling of rail tracks are investigated using dense point clouds obtained from UAV images. Accordingly, a projection-based approach based on the overall direction of the rail track is proposed in order to generate a 3D model of the railway. In order to extract the railway lines, the height jump of points is evaluated in the neighborhood to select the candidate points of rail tracks. Then, using the RANSAC algorithm, line fitting on these candidate points is performed, and the final points related to the rail are identified. In the next step, the pre-specified rail piece model is fitted to the rail points through a projection-based process, and the orientation parameters of the model are determined. These parameters are later improved by fitting the Fourier curve, and finally a continuous 3D model for all of the rail tracks is created. The geometric distance of the final model from rail points is calculated in order to evaluate the modeling accuracy. Moreover, the performance of the proposed method is compared with another approach. A median distance of about 3 cm between the produced model and corresponding point cloud proves the high quality of the proposed 3D modeling algorithm in this study.

scholarly journals Super Edge 4-Points Congruent Sets-Based Point Cloud Global Registration

2021 ◽  
Vol 13 (16) ◽  
pp. 3210
Author(s):  
Shikun Li ◽  
Ruodan Lu ◽  
Jianya Liu ◽  
Liang Guo
Keyword(s):  
Three Dimensional ◽  
Initial Point ◽  
Point Clouds ◽  
Search Space ◽  
Frame Rate ◽  
Registration Method ◽  
Dense Point ◽  
Coarse Registration ◽  
Fine Registration ◽  
Original Point

With the acceleration in three-dimensional (3D) high-frame-rate sensing technologies, dense point clouds collected from multiple standpoints pose a great challenge for the accuracy and efficiency of registration. The combination of coarse registration and fine registration has been extensively promoted. Unlike the requirement of small movements between scan pairs in fine registration, coarse registration can match scans with arbitrary initial poses. The state-of-the-art coarse methods, Super 4-Points Congruent Sets algorithm based on the 4-Points Congruent Sets, improves the speed of registration to a linear order via smart indexing. However, the lack of reduction in the scale of original point clouds limits the application. Besides, the coplanarity of registration bases prevents further reduction of search space. This paper proposes a novel registration method called the Super Edge 4-Points Congruent Sets to address the above problems. The proposed algorithm follows a three-step procedure, including boundary segmentation, overlapping regions extraction, and bases selection. Firstly, an improved method based on vector angle is used to segment the original point clouds aiming to thin out the scale of the initial point clouds. Furthermore, overlapping regions extraction is executed to find out the overlapping regions on the contour. Finally, the proposed method selects registration bases conforming to the distance constraints from the candidate set without consideration about coplanarity. Experiments on various datasets with different characteristics have demonstrated that the average time complexity of the proposed algorithm is improved by 89.76%, and the accuracy is improved by 5 mm on average than the Super 4-Points Congruent Sets algorithm. More encouragingly, the experimental results show that the proposed algorithm can be applied to various restrictive cases, such as few overlapping regions and massive noise. Therefore, the algorithm proposed in this paper is a faster and more robust method than Super 4-Points Congruent Sets under the guarantee of the promised quality.

scholarly journals DEM-Based UAV Flight Planning for 3D Mapping of Geosites: The Case of Olympus Tectonic Window, Lesvos, Greece

2021 ◽  
Vol 10 (8) ◽  
pp. 535
Author(s):  
Ermioni-Eirini Papadopoulou ◽  
Christos Vasilakos ◽  
Nikolaos Zouros ◽  
Nikolaos Soulakellis
Keyword(s):  
Three Dimensional ◽  
Surface Profile ◽  
Point Clouds ◽  
Integrated System ◽  
Slope Aspect ◽  
3D Mapping ◽  
Flight Planning ◽  
Dense Point ◽  
Tectonic Window ◽  
Elevation Model

Geosites are an important part of geoheritage, thus their detailed mapping is crucial for their management, protection and promotion processes. However, there is no specific approach to three-dimensional (3D) mapping of geosites and a full investigation is required, considering the current advances in the science of Geoinformatics and the need for setting up an integrated system that will suggest a suitable way of mapping areas of geological significance. The main purpose of this study is to explore new approaches to the 3D mapping of geosites, where the unmanned aerial vehicles’ (UAVs) flight planning is based on the digital elevation model (DEM). The case study that is being examined is the tectonic window of Mount Olympus, located in the southeast of Lesvos island, Greece. In this paper, a methodology has been developed to create flight plans for geosite 3D mapping. This methodology consists of three main stages: a) flight planning based on SRTM-DEM, b) data acquisition and image-based 3D modelling, and c) comparison (flight plans and results). A semi-automated algorithm was developed for designing the flights, taking into account the topography of the mapped area (slope, aspect, elevation) and the final cartographic derivatives. The flight plans were compared with each other in levels of data collection, flight characteristics and their results. The results of this study are dense point clouds, DEMs and orthophotomaps. The algorithms that have been used for the comparison of point clouds were I) surface density, II) number of neighbours (NN), and III) roughness and surface profile. The conclusion drawn from this study is that the DEM is a valuable source of information that can be used in designing flight plans specially shaped on the topography of each geosite.

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