Ali Reza Torabi, Shahab Amininejad, Filippo Berto,
Volume 15, Issue 9 (11-2015)
Abstract
Notches are one of the most common discontinuities in engineering structures which are created for engineering design purposes. Dealing with V-notches in components made of brittle materials, because of the presence of high stress concentration near the notch tip; detected cracks in this region should be removed and repaired to avoid brittle fracture. The most usual repairing method is to drill a circular hole at the V-notch tip. Clearly, this hole removes the crack and changes the initial notch geometry to a V-notch with end hole. Because of changing the initial notch feature, the load-carrying capacity of the new notch would be different from the initial one. Therefore, in order to assure the safety of the repaired structure, fracture assessment of the new notch is necessary. In the present research, first, a new test specimen, called Brazilian disk containing central V-notch with end hole, made of PMMA is considered for conducting fracture tests at room temperature and the experimental fracture loads are recorded. Some new test results are provided concerning brittle fracture in V-notches with end holes under mixed mode I/II loading. Then, to predict the experimental fracture loads, the strain energy density criterion is utilized. From the obtained results, it is shown that the strain energy density criterion could successfully predict the static strength of notched Brazilian disk specimens for different notch angles and various notch radii.
Volume 16, Issue 1 (March & April (Articles in English & French) 2025)
Abstract
This study aims to analyze the factors associated with motivation and attitude towards English learning through the application of structural equation modeling (SEM). A quantitative, ex post fact, cross-sectional and explanatory study was carried out on 1202 university students. Eight motivational factors were examined, namely: Motivational Intensity (MI), Attitude towards Learning English (ATLL), Integrative Orientation (IntO), Instrumental Orientation (InsO), Interest Towards Foreign Languages (ITFL), Evaluation of English Teaching (EET), Desire to Learn English (DLE), Evaluation of the English Course (EEC). The multiple regressions showed that EET, DLE, InsO, and EEC are predictors of the MI. It was found that DLE, InsO, and EEC are predictors of ATLL. The SEM showed a weak positive influence of InsO on DLE, ITFL, EET, EEC, MI and ATLL. IntO had a weak positive impact on DLE, EET, EEC, and ITFL. There was a weak positive impact of DLE on ITFL, ATLL and MI, and it had a strong effect on EEC. Finally, EET had a weak positive effect on MI, whereas EEC had a weak positive impact on ATTL and MI. This research provided information that serves to understand the factors affecting the intensity of motivation and attitude in L2 learning
Volume 24, Issue 5 (9-2022)
Abstract
Tomato (Solanum lycopersicum L.) production in countries like Mexico relies heavily on the use of chemical pesticides, which can be toxic to a host of other organisms including beneficial insects and human consumers. Environment-friendly methods of controlling tomato diseases include agroecological practices, organic fungicides, and biological control. Plants’ resistance against pathogens is induced by applying agents called elicitors to the plants and would lead to disease prevention or reduced severity. The objective of this research was to know the effect of three elicitor; namely, Activane (1.8 g L-1), Micobiol (3 mL L-1) and Stemicol (2.5 g L-1) plus a control on the incidence of diseases, vigor, yield and fruit quality of two cultivars of Bola tomato and Saladette in the greenhouse. Elicitors decreased the incidence and severity of presented diseases and increased plant survival. Additionally, the elicitors Micobiol® and Activane® were able to increase plant height, stem diameter, weight and fruit diameter, while Stemicol® considerably increased fruit color, °Brix and pH and Activane® increased titratable acid. In general, elicitors were able to reduce disease, increase plant survival, production and improve fruit quality. These findings provide positive directions for the possible use of these elicitors and induce resistance in plant protection.
