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![CT tooth scans with different voxel sizes a) voxel size 41 μm b) voxel size 76 μm c) voxel size 200 μm d) voxel size 300 μm [9]](profile/Michaela-Samardziova/publication/336815174/figure/fig2/AS:826532977184771@1574072226630/CT-tooth-scans-with-different-voxel-sizes-a-voxel-size-41-mm-b-voxel-size-76-mm-c.jpg)
CT tooth scans with different voxel sizes a) voxel size 41 μm b) voxel size 76 μm c) voxel size 200 μm d) voxel size 300 μm [9]
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![Fig. 4 METROTOM 1500 Zeiss [10]](profile/Michaela-Samardziova/publication/336815174/figure/fig3/AS:826532977205250@1574072226660/METROTOM-1500-Zeiss-10_Q320.jpg)
![Fig. 6 CenterMax Zeiss [11]](profile/Michaela-Samardziova/publication/336815174/figure/fig5/AS:826532977209346@1574072226738/CenterMax-Zeiss-11_Q320.jpg)
Production of different kind of parts has increasing character. They are different according to materials, shapes, production technology and accuracy. Possibilities of their quality and accuracy control have to taken into consideration. In addition to optical (non – contact method) and contact (CMM) methods there are applied progressive technologie...
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Context 1
... every angle by rotating the sample 360 degrees, and tomographic images (CT images) are calculated [8]. Fig. 2 Schematic representation of industrial tomograph [8] There is still not enough information or experimental results about how big effect has a voxel size on the final accuracy of the scan. Some papers are dealing with this topic as [9] (Fig. 3). II. EXPERIMENTAL INVESTIGATION The aim of the experiment was in comparison of the accuracy of the scans with different voxel size. METROTOM 1500 (Fig. 4) -X-ray from Zeiss company was used for getting data for this investigation. It is equipment for nondestructive testing of parts made of plastic, ceramics or composite materials, as ...
Citations
... The results were analysed using the GOM Volume Inspector software. The process of CT scan which was used in this paper and the approach for the porosity measurements was studied and described by other researchers [13][14][15]. ...
Additive manufacturing technologies present several advantages over the conventional technologies, like the high flexibility, an easy and fast path to manufacture parts from the CAD file and it is appropriate for manufacturing parts with complex shapes, which are hard or impossible to manufacture with conventional technology. Selective Laser Melting is an Additive Manufacturing technology, suitable for manufacturing metal parts, using a powder that is melted in the desired areas. However, the technology is mostly used for prototyping and one of a kind parts manufacturing, due to relatively high cost and limitations in the dimensions of the parts. This paper aims to study if the properties of the Selective Laser Melted 316L, stainless steel are feasible for manufacturing a part for the automotive industry, specifically brake discs with complex internal structures. Tensile and compressing specimens are manufactured using the Selective Laser Melting technology, to determine the ultimate tensile strength, elongation, and porosity, using computer tomography. The results show that a 99.99% density is achieved, which indicates that the characteristics of the material are not influenced by the porosity and using this technology is suitable for manufacturing brake discs for the automotive industry.
... The longer the radiographic length of the object, the less radiation escapes from the opposite side. The absorption also depends on the material [12]. There are still some problems which need to be solved because scanning accuracy depends, among other things, on the material of parts. ...
... Each voxel (volume pixel) embodies the X-ray absorption by the measured object for a defined location in the measured volume. Similar to two-dimensional image processing, the actual measured points are calculated from the voxel data using a suitable threshold process [12]. ...
The main objective of this research was to analyse the limitations of iCT - industrial computer tomography for measuring the wood pores characteristics as a new non-destructive method which is primarily intended to measure and inspect complete components primarily made of plastics or light metal. The subject matter of this paper are wood samples of paulownia (Paulownia tomentosa) and ash (Fraxinus excelsior) before and after thermal treatment. Porosity, pore volume and distribution of pores on the wood samples before and after the heat treatment were measured by iCT Metrotom 1500. The total porosity of the samples before thermal treatment was 5.28 % (paulownia) and 14.90 % (ash), while after thermal treatment, porosity increased to 9.50 % (paulownia) and to 30.78 % (ash). Changes in the porosity of the samples before and after heat treatment show an increase in porosity of 3.87 % (paulownia) and 15.88 % (ash).
Nowadays, porosity evaluation is a very important part of the production process in the automotive industry and engineering production. The methods used for internal structure evaluation are destructive and non – destructive. One of the most useful non – destructive methods is industrial computed tomography which is based on the application of the X – ray beam in the process of getting data. This method allows evaluation of the external and internal structure from the same data. However, the accuracy of the scan used for porosity evaluation is still in the process of researching. There are not many possibilities for verification of the results because all the analyses are virtual. One of the methods used for results comparison is destructive metallographic cut but it is possible to compare defects only in 2D. Therefore, the idea of creation of the reference sample for porosity evaluation for CT scanning became the aim of this paper. The milled aluminium alloy sample was created from 4 identical parts with hemispherical artificially created defects. Individual parts, that is parts in disassembled state, were measured using focus variation microscopy. The assembly of 4 pieces in one part was followed by a CT scanning process. Comparison shown that the highest relative differences up to 26% were achieved in evaluation of the smallest pore volumes. The smallest relative differences, approximately 2%, were achieved in evaluation of the biggest defects.
Meta-heuristics are widely used methods in OR literature. Whale Optimization Algorithm (WOA) is one of these meta-heuristic methods which is recently developed. The objective of this study is to find the best possible job schedule while minimizing the make-span (i.e., the length of time elapsed from the beginning of first job to the end of the last job.) of the system. This problem is initially solved by using Optimization Programming Language namely CPLEX Studio IDE 20.1.0. Then, WOA which is a current meta-heuristic, used to solve the same problem. Some toy instances of different sizes are created and the results obtained by using CPLEX and WOA are compared. Although, in some studies in the literature, WOA is used to solve job shop scheduling problems, there is not a study which uses WOA as a solution methodology for parallel machine job scheduling problem with machine eligibility consideration to the best of our knowledge. Thus, the main contribution of this study is to include machine eligibility to the conventional job scheduling problem and to use WOA while solving the corresponding problem.
This study solves a one-dimensional cutting stock problem with multiple stock lengths. It is applied in a manufacturing setting where rolls of steel rods of different lengths are cut according to customer requirements. The one-dimensional cutting stock problem (CSP) is an NP-hard problem, including discrete demands and capacitated planning objectives. It is solved using column generation techniques. This study aims to develop a production plan that minimizes the waste of cutting steel rods of different lengths and diameters in required lengths. The approach to solving the problem has two steps. The first step is a heuristic algorithm that produces a cutting pattern at every iteration, which is then fed into a novel mathematical model to determine an optimal solution. An initial solution is obtained using randomly generated cutting patterns for the mathematical model. The algorithm terminates after a given number of iterations. The paper also proposes a Decision Support System, addresses application issues, and concludes with further studies.
