Active thermography : application of deep learning to defect detection and evaluation

La thermographie à phase pulsée (TPP) a été présentée comme une nouvelle technique robuste de thermographie infrarouge (TIR) pour les essais non destructifs (END). Elle utilise la transformée de Fourier discrète (TFD) sur les images thermiques obtenues après un chauffage flash de la surface avant d'un spécimen pour extraire les informations de délai de phase (ou phase). Les gammes de phase calcules (ou cartes de phase) sont utilises pour la visualisation des défauts dans de nombreux matériaux. Le contraste de température permet de détecter les défauts à partir des données thermographiques. Cependant, les images thermiques comportent généralement un niveau de bruit important et des arrière-plans non uniformes causés par un chauffage inégal et des réflexions environnementales. Par conséquent, il n'est pas facile de reconnaître efficacement les régions défectueuses. Dans ce travail, nous avons appliqué la technique LSTM (Long Short Term Memory) et des réseaux de neurones convolutifs (RNC) basés sur des modèles d'apprentissage profond (AP) à la détection des défauts et à la classification de la profondeur des défauts à partir de données d'images thermographiques. Nos résultats expérimentaux ont montré que l'architecture proposée basée sur l'AP a obtenu des scores de précision de 0.95 et 0.77 pour la classification des pixels sains et défectueux. En outre, les résultats expérimentaux ont montré que les techniques LSTM et RNC ont obtenu des précisions de 0.91 et 0.82 pour la classification de la profondeur des défauts, respectivement. Par conséquent, la technique LSTM a surpassé la technique RNC pour les cas de détection des défauts et de classification de la profondeur des défauts.Pulse Phase Thermography (PPT) has been introduced as a novel robust Non-Destructive Testing (NDT) Infrared Thermography (IRT) technique. It employs Discrete Fourier Transform (DFT) to thermal images obtained following flash heating of the front surface of a specimen to extract the phase delay (or phase) information. The computed phase grams (or phase maps) are used for defect visualization in many materials. The temperature contrast enables defect detection based on thermographic data. However, thermal images usually involve significant measurement noise and non-uniform backgrounds caused by uneven heating and environmental reflections. As a result, it is not easy to recognize the defective regions efficiently. In this work, we applied Long Short-Term Memory (LSTM) and Convolutions Neural Networks works (CNNs) based on deep learning (DL) models to defect detection and defect depth classification from thermographic image data. Our experimental results showed that the proposed DL-based architecture achieved 0.95 and 0.77 accuracy scores for sound and defected pixels classification. Furthermore, the experimental results illustrated that LSTM and CNN techniques achieved 0.91 and 0.82 accuracies for defect-depth classification, respectively. Consequently, the LSTM technique overcame the CNNs technique for defect detection and defect-depth classification cases

A micromechanical Sliding-Damage Model Under Dynamic Compressive Loading

For most rock materials, there exists a strong coupling between plastic flow caused by sliding along micro-crack faces and damage evolution due to nucleation and growth of wing-cracks. The aim of this article is to develop the self-consistent based micromechanical model by taking into account the coupling between frictional sliding and damage process under dynamic compressive loading. The developed model algorithm was programmed in the commercial finite difference software environment for numerical simulation of rock material to investigate the relationship between the mechanical behaviour and microstructure. Eventually while the stress intensity factor at flaw tips exceeds the material fracture toughness, the wing-cracks are sprouted and damage evolution occurs. For frictional closed cracks, an appropriate criterion for the onset of frictional sliding along micro-cracks was proposed in this paper. Also, plastic strain increments were determined by the flow rule, consistency condition and normality rule within the thermodynamic framework. The simulation results demonstrate that the developed micromechanical model can adequately reproduce many features of the rock behaviour such as hardening prior to the peak strength, softening in post-peak region, damage induced by wing-cracks and irreversible deformations caused by frictional sliding along micro-cracks. Furthermore, the softening behaviour of material in post-peak region is affected and the material undergoes higher values of strains and damage up to the residual strength. Therefore, the rock sample simulation with the coupled frictional sliding-damage model could increase plasticity and ductility of the rock in post-peak region because of regarding plastic strains caused by the frictional sliding along micro-cracks

Time-Dependent Bearing Capacity Increase of Uniformly Driven Tapered Piles- Field Load Test

This paper describes the results of field load tests on concrete tapered and straight-sided piles driven into a cohesive saturated ground. The piles were driven into a depth of 12 m at a close distance using diesel hammer machine. The soil profile consisted mainly of soft CL and ML in the Unified Soil Classification System. Two piles were tested initially after 35 days from the installation date using maintained load test procedure according to ASTM D1143-81. Then similar tests were performed on two piles after 289 days following the installation date. The results showed the capacities of both piles were roughly identical after 35 days from the installation time. The load-settlement behaviour of tapered showed stiffer than that of the straight-sided pile. After 289 days from the installation date, both piles offered greater bearing capacity values. The long term bearing capacity of a tapered pile was about 80% greater than that of a uniform pile of the same volume and length. In long term, for a given load level applied to the pile heads, the tapered pile offered greater stiffness than the straight-sided pile. This indicates the advantageous use of tapered piles instead of straight sided piles of the same volume and length

Studying the impact of mental health on job performance of managers and staff

The purpose of present research is to study the relationship between job performance and employees’ mental health in one of Iranian natural gas refinery located in city of Jam, Iran. Data collection was conducted based on two major characteristics of job performance and mental health based on questionnaire methods among 42 people. The methodology is descriptive and correlation – type and to analyze the data, Pearson’s correlation coefficient, variances equality tests as well as t-student were utilized. The findings show that there was a significant relationship between employees’ job performance and mental health and any increase in mental health aspects promotes job performance proportionally. In the meantime, there was no significant relationship between employees’ job performance and their gender and there was no significant difference on mental health status between male and female staff. Based on the results, one can conclude that low mental health level among employees can reduce their performance. Managers should use proper methods to decrease the negative consequences resulted from the lack of mental health in workplaces

Fundamentals of quittance and responsibility in case of committing an error in Shiite Jurisprudence

Saving patients' lives is an important duty for physicians. Regardless of the level of a physician’s skills, there is always a possibility of damage or loss in patients’ life. In jurisprudence, there is a dispute as to whether a physician is responsible if he commits medical mistakes in the course of treatment. Some scholars believe that a physician is always responsible for damages related to his professional mistakes whether he has obtained permission or not. They base their arguments on the generality of the related narrations of ajir (hired) and juridical rules such as Itlaf (destruction), Tasbib (causing damages), La darar (denegation of harmfulness) and Qorur (deception). On the other hand, some others believe that physicians are never responsible for such damages. They base their arguments on the Ihsan (beneficence) rule and Bara’ah (quittance) principle. They argue that physicians have not undertaken achieving the improvement result and they are merely responsible for treatment of the patients. According to Bara’ah principle, physicians could be released from such responsibility. In other words, they are always responsible unless they obtain quittance from their patients. This argument is based on the general rules of al-osr wal-haraj (denegation of hardships) in the society along with Sokuni’s narration. In addition, the necessity of commitment to conditions is another reason for this argument. Exploring the grounds of responsibility (al-ziman) and the grounds for their release from al-ziman the latter argument proves to be more acceptable. Therefore physicians should obtain permission from the patients or their guardians before taking medical actions and also the veterinary should obtain quittance from the owner of animal. Theses evidences are stronger and they are not responsible after obtaining quittance. Keywords Physician, responsibility, quittance, permission, rule, isqat, talaf, ihsan, ibra

Variation in the Quality of Forage of Six Rangeland Species in Different Phenological Stages

An understanding of forage quality is fundamental to the measurement of grazing capacity. In addition, knowledge of forage quality is necessary for planning grazing and developing range improvement and development programmes, such as planting and seeding of rangelands. Among the different factors that affect forage quality, phenological stage is particularly important (Cook, 1972; Caballero et al.,2001). The objective of this study was to investigate the effects of plant species, phenological stages and life form on forage quality indices

A Comparison and Evaluation of the Views and Arguments of Commentators and Scholars About the Quality of Torment of Metamorphosis

The torment of metamorphosis is one of the traditions of divine correction that afflicts a person or special group following religious and moral deviations. Such a tradition is reported in the verses of the Qur'an in two ways: One of them is apparent metamorphosis that belonged to the people of Israel Who suffered it for disobeying the ban on fishing and using trickery. And the other is spiritual metamorphosis that is general and not belong to a particular nation and all human beings are suffered to it. Many verses with different words have reminded of the second type of torment. There is disagreement among the commentators of Sunni and the Shiite about the formal metamorphosis of the children of Israel. This difference has led to three views among them with different arguments. The Wise Men, especially the followers of Sadra's wisdom, while adhering to the appearances of verses and hadiths, based on the theory of divine metempsychosis and the type of types, it provides a more accurate approximation that includes external and internal metamorphosis. These views are based on the sequence of the bodies of the population and attention to the middle type and the lower genius. In this research, by means of content analysis. We will examine and evaluate the views and reasons of commentators and scholars about the quality and types of metamorphosis