Articles
Publication Date: 2023
Journal of Vinyl and Additive Technology (15480585)29(5)pp. 849-863
An epoxy-based intumescent coating containing the silica and zinc borate nanoparticles was fabricated. The fire performance of the coating with the optimum formulation was investigated in terms of the changes in the physical and chemical structure of the formed char layer during the exposure to a temperature of 1000°C. The state of the chemical structure was analyzed by performing the Fourier-transform infrared spectroscopy, x-ray diffraction, and x-ray photoelectron spectroscopy analysis from the char layer at the three-time intervals of 10, 30, and 60 min of the heating process. The innovative Condorcet method was also employed to examine the changes in the physical structure of the formed char layer. Some instabilities were detected in the physical structure of the char layer in the middle period of heating. Moreover, a gradual formation of silicon carbide crystalline structure was observed on top of the surface, followed by its oxidation to silica over time. In contrast, in the bulk structure, silicon crystalline structures (Coesite) intensified with time. Boron nitride was also increasingly created on the top surface and in the bulk of the coating over the heating time. These findings proved the effective role of the silica and zinc-borate nanoparticles in the fire performance of epoxy-based intumescent coatings. © 2023 Society of Plastics Engineers.
Publication Date: 2020
Journal of Cultural Heritage (12962074)45pp. 204-214
In this paper, a new system for automatic drawing of bas-reliefs is presented. The system consists of a fringe projection scanner accompanied by a photometric stereo component. At first, the photometric stereo is used to accurately extract normals of the relief surface. Using a line tracing algorithm the normals are converted into 2D lines. Then, using the fringe projection scanner, the 2D lines are transformed to the 3D space to form a metric map required for cultural heritage applications. To evaluate the system, several tests were carried out using artificial and real bas-reliefs. The results showed that the system is able to draw 98.8% of the object lines correctly. © 2020 Elsevier Masson SAS
Publication Date: 2019
CTIT workshop proceedings series (16821750)42(4/W18)pp. 483-488
In recent years, the applications of interior and exterior model of buildings have been increased in the field of surveying and mapping. This paper presents a new method for extracting a two-dimensional (2D) floor plan of a building from Simultaneous localization and mapping (SLAM)-based point clouds. In the proposed algorithm, after preprocessing, the voxel space is generated for the point cloud. Then, the optimal section of the voxel cube to generate building floor plan is identified. Finally, the linear structures and walls are extracted using the random sample consensus (RANSAC) algorithm. The proposed algorithm was examined on a collected point clouds of a building, and the walls of this building were automatically extracted. To evaluate the proposed method, the obtained walls by the algorithm were compared with the manually extracted walls. The algorithm successfully extracted almost 90% of the walls in the test area. Moreover, the average error of 3 cm for the extracted walls proved the high accuracy of the proposed method for building floor plan modeling. © 2019 M. Hossein Pouraghdam et al.
Publication Date: 2019
Photogrammetric Record (14779730)34(165)pp. 63-84
This paper proposes a new fringe projection scanner that uses a dual pattern to prevent phase retrieval errors or complications. The pattern comprises two horizontal and vertical patterns, however, just one of them is involved in computing the coordinates of an object point. To define the pattern, a photometric stereo component is used to extract the geometric properties of the object. The extracted data is employed to form a decision mask, each pixel of which defines the best pattern (horizontal, vertical or both) related to one of the object points. In this way, the scanner determines which pattern to use to obtain the most accurate results. Experiments suggest not only the avoidance of phase retrieval problems, but also an increase in the accuracy of the measurements (by 56% in this test). © 2019 The Authors. The Photogrammetric Record © 2019 The Remote Sensing and Photogrammetry Society and John Wiley & Sons Ltd
Publication Date: 2019
CTIT workshop proceedings series (16821750)42(4/W18)pp. 7-12
Geometric documentation is one of the most important parts of a documentary report. Despite the advances made in the field of line drawing of ancient relief surfaces, in most cases, human operator interaction is unavoidable. In this paper, an algorithm for the semiautomatic line drawing of relief surfaces has been developed. In the proposed method, photometric stereo normals are used as a highresolution and low-noise data for the automatic extraction of surface edges. The normals are computed in 2D image space and also the fringe projection scanner is used for geometric correction of 2D image based drawings. Therefore, the drawings are converted to a metric map for geometric documentation reports. The results show that the efficiency of the proposed method, which has managed to correctly draw about more than 99% of the edge lines of an ancient relief. Also all of the drawn lines are completely coincided to the relief edges on its orthophoto image. © 2019 A. Abzal et al.
