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Dovom-niasar, S.J. ,
Seifi, A. ,
Bahramian, A.R. ,
Abzal, A. 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.
Abzal, A. ,
Saadatseresht, M. ,
Varshosaz m., M. ,
Remondino, F. 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
Hossein pouraghdam m., ,
Saadatseresht, M. ,
Rastiveis h., ,
Abzal, A. ,
Hasanlou m., 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.
Abzal, A. ,
Saadatseresht, M. ,
Varshosaz m., M. 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
Abzal, A. ,
Saadatseresht, M. ,
Varshosaz m., M. 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.
Abzal, A. ,
Saadatseresht, M. ,
Varshosaz m., M. ISPRS Journal of Photogrammetry and Remote Sensing (09242716) 142pp. 12-20
Most optical scanners work based on a fix resolution and, thus, produce a huge number of points, many of which are usually redundant. Therefore, an intensive post-processing step is required to simplify the resulting point cloud. In this paper, a novel technique is proposed that does not require the post-measurement calculations; instead, it reduces the scanned points at the data-acquisition phase. For this, the surface curvatures of object points are determined using the photometric stereo. Then, the curvature values are classified based on an adaptive sampling interval which is defined through an innovative calibration process. Once the curvature ranges are identified as such, a simplification mask is created. The mask is a binary image that is used to show points in the image space the optical scanner requires to decide if the 3D coordinates of an object point need to be computed. Having evaluated the proposed method using a fringe scanner, we observed that, although the data acquisition time is slightly increased, the number of redundant points is notably reduced. Therefore, not only the production of unnecessary data is prevented by 71–90% (depending on the surface complexity), but also carrying out the intensive post-processing simplification step is totally avoided. © 2018
Advanced Materials Research (discontinued) (16628985) 301pp. 388-396
Cyclic axial loads in steel tubular might lead to local buckling, wrinkling and accumulation of plastic strains in the tube. During their life time steel tubes may also experience different types of material loss such as corrosion or thinning. This paper deals with the effects of corrosion defects on the strain ratcheting response of steel tubes. Small scale un-corroded and corroded tubular specimens have been tested under monotonic and cyclic axial loads. Optical system ATOS has been used for 3D surface acquisition and reconstruction of the tested specimen and to evaluate their strain ratcheting and wrinkling response. This is a camera-based triangulation system. A processing unit employs optical transform equations to automatically and with a great accuracy calculate 3D coordinates for every pixel of camera. Depending on camera resolution as an effect of such a scan a cloud of up to 4 million points has been obtained for every single measurement. From the results, it has been noticed that the possibility of ratcheting or progressive plastic failure substantially increases by the presence of the corrosion defects. With the corroded specimens, the strain ratcheting behaviour in the defected zone has been distinctively different from that in the perfect zones.
Abzal, A. ,
Varshosaz m., M. ,
Saadatseresht, M. Photogrammetric Record (14779730) 26(135)pp. 293-306
In this paper a new triangulation-based laser scanner is presented which has a simple, yet strong, flexible and low-cost structure. A digital camera and three laser line projectors are the main components of the system. One of the laser projectors is positioned vertically, while the other two are horizontal. The former scans the object, whereas the latter two establish an optical frame which is used, in part, to define the plane containing the vertical laser projector at each step of scanning. At each step, an image is taken which includes the object along with the projected laser lines. By intersecting the vertical and horizontal lines a couple of points are formed which, along with the calibration information of the system, enable the extraction of the object coordinates. Results of the tests carried out show that by using an optical frame of this nature, the process of scanning is greatly facilitated. That is, the scanner can easily be used to scan objects of different size and dimensions. Within the current configuration, the system enables measurements with an accuracy of 1/1600. Also, as the system has a rigorous basis, its accuracy can be increased if improved hardware is provided. © 2011 The Authors. The Photogrammetric Record © 2011 The Remote Sensing and Photogrammetry Society and Blackwell Publishing Ltd.
