Impact analysis of actuator torque degradation on the IRB 120 robot performance using simscape-based model

Actuators in a robot system may become faulty during their life cycle. Locked joints, free-moving joints, and the loss of actuator torque are common faulty types of robot joints where the actuators fail. Locked and free-moving joint issues are addressed by many published articles, whereas the actuator torque loss still opens attractive investigation challenges. The objectives of this study are to classify the loss of robot actuator torque, named actuator torque degradation, into three different cases: Boundary degradation of torque, boundary degradation of torque rate, and proportional degradation of torque, and to analyze their impact on the performance of a typical 6-DOF robot (i.e., the IRB 120 robot). Typically, controllers of robots are not pre-designed specifically for anticipating these faults. To isolate and focus on the impact of only actuator torque degradation faults, all robot parameters are assumed to be known precisely, and a popular closed-loop controller is used to investigate the robot’s responses under these faults. By exploiting MATLAB-the reliable simulation environment, a simscape-based quasi-physical model of the robot is built and utilized instead of an actual expensive prototype. The simulation results indicate that the robot responses cannot follow the desired path properly in most fault cases

Diversity of plant-parasitic nematodes on medicinal plants in Melinh station for biodiversity, Vinh Phuc Province, Vietnam

Plant-parasitic nematodes are known as one of the most important pests attacking various plants in the world, and investigating the nematode component is very essential for management of this pest and prevent damage to plants in general. Our survey of plant-parasitic nematodes on medicinal plants in Melinh Station for Biodiversity, a place for conservation of precious plants and animals in Vietnam, identified ten species that belong to nine genera, five families, and two orders of plant-parasitic nematodes parasitizing six medicinal plants. Excoecaria cochinchinensis was parasitized by the highest number of nematode genera (5 genera, including Xiphinema, Discocriconemella, Meloidogyne, Helicotylenchus, and Hemicriconemoides), while Hymenocallis littoralis was associated with the highest number of plant-parasitic nematodes (2060 nematodes/250g soil). The results also showed that Discocriconemella limitanea was found to be a dominant species with the highest number of individuals on 6 medicinal plants, and the genus Helicotylenchus had the highest frequency of appearance (5/6 plants or 83.3%). These nematodes caused symptoms such as yellowing leaves, root galls, and root lesions, which directly affect the quality and yield of medicinal plants. Based on the results, this study showed that plant-parasitic nematodes are a potential threat to the cultivation of medicinal plants in Melinh Station for Biodiversity, and thus, control measures should be applied to ensure sustainable cultivation of medicinal plants in this place

A Planning Experimental Investigation on Tobacco Leaves Dryer Using Paddy Husk and Coal

In Viet Nam, the drying technology and techniques for tobacco leaves is one of the most difficulties and plays as key point to get high economic efficiency in tobacco production. To drying for tobacco leaves of 3,500 hectare, for example in Gia Lai province, there needs about 3000 dryers and there is more than 100,000 cubic meter of wood have been burned for drying which equivalent to more than 300 hectare of forest is deforested annually. A designing and manufacturing study for new tobacco dryer to replace the wood fuel by paddy-husk or coal-wood has been implemented. The results indicate that the new dryer using rice-husk or coal can be replaced for the actual drying system used fire wood with the high quality of tobacco leaves and high efficiency. The planning experimental investigation has found the function of the rate of energy consumption and the quality of drying products successfu

First report of Longidorus mindanaoensis Coomans, De Ley, Jimenez and De Ley, 2012 (Nematoda: Longidoridae) from a mangrove forest in Vietnam

Longidorus mindanaoensis was recovered from a mangrove forest in Vietnam. The recovered population is in general morphological agreement with the type population, and the characters of pharyngeal bulb, i.e. the same unique pattern of pharyngeal glands nuclei as well as the lip region morphology, amphidial fovea shape and size and position of vulva corroborated its identity. Molecular studies of the recovered population using D2-D3 expansion segments of large subunit ribosomal DNA (LSU rDNA D2-D3) revealed the D2-D3 sequence of the recovered population is 99.6% similar to the sequence of the type population. A new morphometric range for body size was recorded for the species based upon present Vietnamese population, and the present study emphasized that the diversity of Longidorus spp. in Vietnam could be higher than previously assumed

Morphological diversity of Meloidogyne spp. from carrot (Daucus carota subsp. Sativus) in Vietnam

Carrot (Daucus carota subsp. Sativus) is known as one of the most widely cultivated and widely consumed vegetables in the world due to its nutritional and economic values. During a survey of nematodes parasites carrots from Vietnam, six populations of three species of root-knot nematodes, namely M. incognita, M. arenaria, and M. graminicola were found. The species specific primers were confirmed before morphological studies. By combining the morphology and morphometry of the females, males, and juveniles, this study provided useful references for classification of Meloidogyne on carrots in the future. Quantitative morphological studies reveal profound changes corresponding with the generation of morphological disparity at high taxonomic diversity. Especially, this study provided the first morphological and morphometric information of M. graminicola, that is known as aquatic root-knot nematodes, on carrots

Bioconvection gravitactique dans un milieu stratifié

International audienceNous considérons le phénomène de bioconvection gravitactique dans une cavité rectangulaire poreuse saturée d'un fluide stratifié. La bioconvection est due aux mouvements ascendants des micro-organismes qui sont légèrement plus denses que l'eau, tandis que la stratification du fluide est d'origine solutal et joue un rôle stabilisant. Il sera montré que la bioconvection stationnaire dans un milieu stratifié est un phénomène d'instabilité sous-critique qui est due d'une part au mouvement gravitactique des micro-organismes, et d'autre part à la faible diffusivité des solutés par rapport à celle des micro-organismes. Il sera aussi montré qu'il existe un régime de bioconvection oscillante qui peut s'établir en-dessous du seuil critique du régime de bioconvection stationnaire

CURRENT SITUATION OF STUDENTS’ PSYCHOLOGICAL STATE BEFORE PRACTICAL COURSES’ FINAL EXAMS

The article aimed to determine the factors influencing students’ psychological state before the final exam of practical courses. The article used conventional scientific research methods in sports and physical training combined with psychological tests studied on fifty students at Ho Chi Minh City University of Physical Education and Sports (UPES). After reviewing related studies and consulting with experts, four tests were employed to assess the psychological state before the test of the research subjects. The results showed that students with a good psychological state to take the exam had good test results. Conversely, students with a feverish or lethargic state will have poor test results. The research results serve as the basis for proposing measures to adjust the psychological state before the exam, contributing to improving the learning results of students.  Article visualizations