جستجوی مقالات مرتبط با کلیدواژه « radiography » در نشریات گروه « فنی و مهندسی »

A fire extinguisher is a critical piece of safety equipment used to suppress or extinguish small fires in emergency situations to prevent large and deadly fires. This study examines the possibility of using a measurement system based on a transmitted gamma ray and a linear pixel needle detector of a vehicle cargo scanner based on gamma ray technology to inspect fire extinguishers.. The aim is to determine the effectiveness and accuracy of this approach in detecting any defects or irregularities in fire extinguishers, which would enhance the safety and reliability of these crucial emergency devices. The study involves testing the system on four different models of fire extinguishers and analyzing the results to assess its viability as an inspection method. The results were analyzed, with output in the form of images and intensity profiles recorded in one direction from the images. The findings of this research could have a significant impact on the field of fire safety. They could help to contribute to the development of more advanced and efficient inspection techniques for fire extinguishers, in conjunction with other non-destructive inspection methods. In this study, the capabilities, limitations and potential applications of a transmission gamma based imaging system for fire extinguisher inspection were investigated.The imaging unit utilized a gamma source of cesium-137 and a linear detector array. The study discusses the potential applications of this technology in the field of fire safety and its limitations. The research highlights the importance of developing more advanced and efficient inspection techniques for fire extinguishers, as well as the need for ongoing research in this field. Ultimately, this study provides valuable insights into the potential use of vehicle cargo scanner systems for the inspection of fire extinguishers, and its findings have important implications for the field of fire safety. The results provide valuable insights into the feasibility of using gamma-ray technology-based automotive cargo scanner systems and pixel linear detectors as a reliable method for fire extinguisher inspection, ultimately enhancing public safety and emergency preparedness.

The line of welds in welding may contain defects that cause irreparable damage to the entire project. Therefore, it is necessary to check the quality and strength of the welding line. There are several ways to evaluate this quality. Among the non-destructive testing methods, or NDT for short, that do not change the properties of the object under inspection and include X-ray, visual method and use of ultrasonic method. These images should be reviewed by weld line inspectors. Sometimes these x-ray images are of low quality due to the problems that arise in the process of imaging or digitizing and transferring them. In this article, we will try to improve the quality and clarity of the defects of these images. In this proposed method, after scanning and digitizing the images, an attempt has been made to remove the noise and increase the quality of their resolution with image processing methods, which include textural equalization, stretching the difference in color brightness, sharpening the edges and reducing noise, as well as morphological operations. Finally, the amount of quality improvement has been evaluated quantitatively using methods such as mean square error and peak signal-to-noise ratio. The results of using this method, which are in the quality determination section, clearly show that the images are of better quality than other methods.

Identifying the internal components of old specimens such as antique guns is very important to restoration experts in terms of the internal design and their connections. It is also important to check the safety of the weapon in terms of whether it is full or empty or how the cartridges are positioned. In this case study, radiography testing was used to investigate the condition of two antique guns, revolver and colt. Image processing techniques based on the curvelets was used to for better evaluation of the radiographs. The results show that radiography provides good information in revealing the internal structure and the parts arrangements in the two weapons. Their processed images also provide more detailed and accrued information. Experts have confirmed the radiographic information in the two guns and their internal structure and defects and and also confirmed the efficiency of the “curvelet” wavelet method for the definition increasing of the images up to 25%.

Art paintings are valuable cultural assets in any country that they are always threatened by dangers such as rupture, scratches, and loss of pigments. Natural disasters, irresponsible handling, exposure to light and temperature changes are all dangers factors. Various non-destructive methods such as radiography testing (RT) and ultraviolet (UV) inspection can be used to identifying detect the location of defects without any damage the paintings. The radiography testing recognized hidden patterns and deep defects and the general structure of the painting due to the penetration of X-rays to the lower surfaces. In the ultraviolet inspection, information about scratches and surface defects is obtained, depending on the type and material of paint used. Images of both methods provide excellent information to restoration experts, but problems such as blurring images of the RT and UV inspection darkening of some colors under ultraviolet light make it difficult to identify the defect regions. It is appropriate to use image processing techniques as an auxiliary tool to increase the contrast of the image. In this research, the Gabor filter has been used to increase the quality of the RT and UV images and reduce the blur of images; The Gabor filter use an automatic threshold level based on the deviation and mean pixel information of the images. Images reconstructed by the Gabor filter are efficient in identifying hidden designs and the location of defects.

Friction stir welding (FSW) is an economic and high quality technique at aluminum welding and joining methods. The most important factor in the soundness of this type of welding, is the mechanism of material transfer in each tool rotation. The materials transfer during the welding process involves horizontal and vertical movement that caused by extrusion process and forging force (the tilt angle due to forging force and on the other hand, shape of pin due to the extrusion process). One of the most important parameters in FSW process is the effect of rotational speed in the welded zone. In this study, the effect of rotational speed at constant welding speed, in the butt joint of pure commercial aluminum, was investigated. The results of the study showed that, increasing the rotational speed due to increases the amount of material transfer in the weld zone. The welded zone was investigated by appearance weld zone experiments and using radiography tests. Also weld zone was investigated in macro and microstructure by using cross section. Then the micro hardness testing has been used by cross section at welded zone. In order to investigate the mechanism of materials transfer during the process, the electrical resistivity test has been used to analyses the amount of materials transfer in the weld zone. Results shows that, increasing rotational speed due to increasing the amount of materials transfer in the weld zone and decreasing the amount of defects in the weld zone.

Fractures and damages can be resulted from physical stresses in the flawed parts of an aircraft. The exact detection of internal defects is possible by radiography testing. The determination of the defects locations by the experts depends on the accuracy, skill and quality of the radiographs. Many of the produced images by industrial radiography are not clear, and it is difficult to accurately detect their defects; hence, the processing methods can help to better investigation of the defects. These images suffer from some opaqueness due to the inherent dispersion of X-rays. In this study, a non-local mean method based on thedetection of similar pixels in a neighboring area is used to identify corrosion areas. In the method, the image is split into smaller windows and the similar pixel is found on these parts. The results of the method show that, due to the lack of noise function in radiographic images, the background elimination method is more suitable for this algorithm. In this research, the large amount of standard deviation of the noise is considered and background is extracted, the obtained image was reduced from the original radiographic image. The reconstructed image has sharp edges that more clearly indicates the defect area. The evaluation of the results by radiography experts showed that this method has the efficiency to detect defects

Bubble damage is a casting defect related to the air entrainment as a result of unsuitable running system design and surface turbulence. In this work, effects of gate velocity on the formation of bubble damage in Al-5Mg and 413 casting alloys are investigated. Gate velocity was changed by increasing the sprue height and decreasing the ingate area. After casting radiography of plates and three points bend test, on samples taken from plates, was performed. Fractography of samples by SEM and quantitative analysis by EDS were also applied. Results show that size and quantity of entrapped air bubbles are increased as a result of increase in gate velocity. Area fraction and size of bubbles entrained in Al-5Mg alloy seems to be eight folds higher in comparison with 413 Al alloy. This observation confirms the hypothesis of the effect of oxide films thickness on the intensity of bubble damage in various Al alloy.

In this research, Low Pressure Casting (LPC) and solidification simulation of a high class A357 complex part, by ProCast software was developed and mechanical properties and radiographic grade of this part was evaluated and matched to military standard requirements. Due to incorporation of experimental results with simulation ones, the experimental data bases which was included mechanical properties of A357 alloy as a function of Secondary Dendrite Arm Spacing (SDAS) and radiography test (RT) results was used for software calibration. Finally on the base of simulation results which confirmed with experimental tests, a model for mechanical properties of A357 alloy was developed. Solidification defects and micro porosity shrinkages of the aero part as radiographic grade were predicted. Thus optimized chilling method and injection temperature for eliminating of solidification defects was demonstrated.