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Achraf Ammar Hamdi Chtourou Khaled Trabelsi Johnny Padulo Mouna Turki Kais El Abed 《Journal of sports sciences》2015,33(4):358-368
The aim of this study was to investigate the performance of an Olympic-Weightlifting session training at three times of the day on the performance related to biochemical responses. Nine weightlifters (21 ± 0.5 years) performed, in randomised order, on three Olympic-Weightlifting training (snatch, clean and jerk) sessions (08:00 a.m., 02:00 p. m., 06:00 p. m.). Blood samples were collected: before, 3 min and 48 h after each training session. Haematological parameters and markers of muscle injury were assessed. Resting oral temperature and rating of perceived exertion (RPE) were also assessed during each session. ANOVA showed that the performance was better (P < 0.001) at 02:00 p. m. with a less RPE (P < 0.01) compared to the morning and the evening sessions while there was higher (P < 0.05) oral temperature at 06:00 p. m. versus 08:00 a.m. and 02:00 p. m. Muscle damage changed immediately (without significant effect after 48 h) after the training sessions with lower values ??in the evening compared to the morning. In conclusion, the afternoon training is more effective than morning or evening sessions for weightlifters. Therefore, coaches and weightlifters should be advised to schedule their training session in the afternoon hour. 相似文献
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Latifa Ouertatani Alain Dumon Malika Ayadi Trabelsi Mohamed Soudani 《International Journal of Science and Mathematics Education》2007,5(3):483-506
In this work, we propose to identify the knowledge that Tunisian grade 10 students build up concerning acids and bases. Thus, after learning, we have proceeded by giving a paper and pencil task to students of two levels of teaching. The results obtained allow us to say that the assimilated knowledge is transitory; that the students have a worse perception of the base than of the acid concept and these two concepts are independent; that they associate the acid or base strength to its concentration; that the pH is far from being a “tool” of estimation of the degree of acidity; and that the students have difficulty in linking the empirical and the models’ registers. Moreover, some alternative conceptions that can be harmful to the learning of Brønsted’s model appear. 相似文献
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Shilpa Sivashankar Sumeyra Agambayev Yousof Mashraei Er Qiang Li Sigurdur T. Thoroddsen Khaled Nabil Salama 《Biomicrofluidics》2016,10(3)
This paper proposes a new “twisted” 3D microfluidic mixer fabricated by a laser writing/microfabrication technique. Effective and efficient mixing using the twisted micromixers can be obtained by combining two general chaotic mixing mechanisms: splitting/recombining and chaotic advection. The lamination of mixer units provides the splitting and recombination mechanism when the quadrant of circles is arranged in a two-layered serial arrangement of mixing units. The overall 3D path of the microchannel introduces the advection. An experimental investigation using chemical solutions revealed that these novel 3D passive microfluidic mixers were stable and could be operated at a wide range of flow rates. This micromixer finds application in the manipulation of tiny volumes of liquids that are crucial in diagnostics. The mixing performance was evaluated by dye visualization, and using a pH test that determined the chemical reaction of the solutions. A comparison of the tornado-mixer with this twisted micromixer was made to evaluate the efficiency of mixing. The efficiency of mixing was calculated within the channel by acquiring intensities using ImageJ software. Results suggested that efficient mixing can be obtained when more than 3 units were consecutively placed. The geometry of the device, which has a length of 30 mm, enables the device to be integrated with micro total analysis systems and other lab-on-chip devices. 相似文献
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Andrea Conchado Peiró Khaled M. Gharaibeh Hazem Kaylani 《European Journal of Engineering Education》2017,42(5):547-560
The objective of this study is to identify the competencies required to achieve success in the transition from higher education to the labour market based on the perceptions of employers. This paper analyses the assessments made by a group of engineering company employers. An item-battery of 20 competencies was grouped into 3 dimensions by using factor analysis. Subsequently, respondents’ scores were also clustered into three groups and characterised through contingency tables. The competencies demanded by employers were grouped into business and finance, problem-solving and strategic planning. Significant differences were found between responses from employers working in medium and small companies, who placed more importance on competencies related to problem-solving and strategic planning, and employers in big companies, who were more concerned about the difficulties of finding well-trained graduates. The findings from this paper have important implications for research in the areas of higher education and organisations that usually employ graduate engineers. 相似文献
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We examined the effectiveness of perceptual training on the performance of handball goalkeepers when anticipating the direction of both direct and deceptive 7-m throws. Skilled goalkeepers were assigned equally to three matched-ability groups based on their pre-test performance: a perceptual training group (n = 14) received video-based perceptual training, a placebo training group (n = 14) received video-based regular training and a control group received no training. Participants in the perceptual training group significantly improved their performance compared to both placebo and control groups; however, anticipation of deceptive throws improved less than for direct throws. The results confirm that although anticipating deception in handball is a challenging task for goalkeepers, task-specific perceptual training can minimise its effect and improve performance. 相似文献
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Khaled Abu Asbah 《Diaspora, Indigenous, and Minority Education》2018,12(1):1-13
Education for multiculturalism, founded on liberal-democratic values, is a frequent topic of educational discourse that has not been ignored by Muslim Arab schools in Israel. In general, Arab society is undergoing change processes, in transition from a traditional to a modern society; traditional values are challenged, engendering social crises. This paper discusses whether the multicultural approach can be successfully imparted in a society with preexisting structured values. It focuses on the school’s role as a socialization agent that needs to adapt itself to a changing sociocultural reality, discussing the school’s involvement in creating a value crisis, since it transmits the Islamic perception of the principles, foundations, and goals of education for multiculturalism. It is concluded that education for multiculturalism in Arab schools lacks internal logic, conflicts with and even undermines the Arab society’s sociocultural values system, is inappropriate as a means to supervise the necessary change processes, and thus contributes to a values crisis. 相似文献
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Hamdi Echeikh Ramzi Trabelsi Atif Iqbal Med Faouzi Mimouni 《Journal of The Franklin Institute》2018,355(5):2112-2141
High performance multiphase motor drive requires precise knowledge of the state quantities and the machine parameters. Access to these state quantities is through measurement using sensors whose accuracy is paramount to achieve the performance level required by industrial applications. However, the problems of the parameters variations, inaccessibility to the measurement of some states, no-observability of the machine in some regions, the cost of the sensors and their lack of precision, make this very difficult task. To address these problems, it is necessary to resort to soft sensors through the design of observers and estimators. In multiphase induction motor drive, the observation problem arises especially for rotor flux that is not accessible for measurement. About the parameters variations, the rotor resistance and the stator resistance are the most critical parameters of the machine because their influence is crucial for the control and observation. The change in the resistances can be as large as 40–50% of the rated value, which may affect the control adversely. This paper develops a new structure of an adaptive sliding mode observer based on an online estimation of the rotor resistance value in order to avoid the effect of its variation in the rotor flux oriented control. The results show convergent (the errors in the transient and steady states are 5% and 1%, respectively) behavior of the drive using the proposed control scheme for large rotor resistance variation under loaded condition. The stability of the drive is proved using Lyapunov criteria. The simulation results are validated using real time implementation. 相似文献
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This study tested the mediating role of self‐directed learning skills (SDL) between students’ conceptions of mathematics and their achievement in mathematics using a structural equation model. Data were collected using the “Conceptions of Mathematics Questionnaire” and the “Self‐Rating Scale of Self‐Directed Learning”, together with students’ achievement in mathematics. A sample of 440 first year university students at King Saud University participated in the study. The findings confirm the moderating role of students’ self‐directed learning skills between their conceptions of mathematics and their achievement in mathematics. Students who have a highly fragmented conception of mathematics tended to have low SDL skills, and in turn low mathematics achievement (partial mediation), whereas students who have a highly cohesive conception of mathematics tended to have high self‐directed learning skills, and in turn high mathematics achievement (full mediation). Mathematics educators should be aware that students’ conceptions of mathematics may be influential, but not sufficient to predict achievement in mathematics. Equipping students with appropriate conceptions of mathematics and self‐directed learning skills is key to enhancing their performance in mathematics. 相似文献