The effects of online social networks on the quantitative academic performance of secondary high school girls' students in Tehran

Background and Objectives: One of the important indicators in measuring the quality of education is the academic performance of students, which is important from a scientific and practical point of view. Extensive studies have been conducted worldwide on how social networks affect the quantitative academic performance of their students. Many studies on the denial of social media have concluded that these networks have a negative impact on the younger generation and students. These researchers believe that virtual social networks have an effect on students' annual grade point average, drop in academic grades, writing style and spelling, decrease in English language standards, etc., and have measured these variables separately with the use of social networks among students. At the same time, others believe that the emergence of social media has a positive trend on students' performance and their achievement of high grades. These studies have also found that these students spend most of their time doing their homework and research in this way. Therefore, in the review of previous studies, both approaches are discussed separately. The main purpose of this study is to be aware of the impact of virtual social networks on the quantitative academic performance of female high school students. Sub-objectives are to examine the extent of students 'dependence on virtual social networks and awareness of the impact of using virtual social networks on students' quantitative academic performance. Methods: In this research, a survey method has been used and the sample population includes 855 female students of high schools in Tehran. The data gathering instrument is Jeffrey Single's Social Media Dependency Questionnaire, including academic quantitative performance, social networks addiction, educational use, and grammar, writing, reading, and course questions. In this study, descriptive tests (percentage, mean, and analytical tests (chi-square, Pearson correlation coefficient and t-test) were used. Findings: The findings show that there is no relationship between the students' last year GPA and their academic quantitative performance and their use of the online social network; but there is a relationship between their GPAs and their scientific information exchange (test questions) and with their use of online social networks. The findings show that there is no relationship between last year's students' grade point average and their poor academic performance using a virtual social network. There is only a relationship between their grade point average and the exchange of scientific information (exam questions) through social networks. There is also a link between social media use and poor academic performance, social media addiction, learning and receiving questions and course questions. However, the effect of social networks on the quantitative performance of students is moderate and its effect on other educational activities of students is low. Conclusion: Online social networks can be used as an appropriate way of interaction between students, as well as between teachers and students to convey scientific content, share questions and problem-solving skills, and help each other understand the correct path to problem solving. Although in this study, the use of virtual social networks does not have a negative effect on students' quantitative academic performance, but it should be noted that membership in these networks as a group and as a channel if it creates dependency and students spend a lot of time in their school hours. Can affect the quantitative academic performance of students. ===================================================================================== COPYRIGHTS  ©2020 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.  ====================================================================================

Developing sustainable SCM evaluation model using fuzzy AHP in publishing industry

In the new econo mic context the long term success of any organization is built not only on profits and profitability but also on its contribution to the future of people and the future of the planet. Being supply chains a key cornerstone in any organization the consideration of sustainability at the supply chain level is recognized as an emerging area that needs to be studied in a systematic way. In this paper we proposed a fuzzy AHP approach for evaluating of SCM sustainability in publishing industry. For this work, we define a hierarchical framework regarding with Ageron et al model and criteria and sub criteria based on viewpoints of practical and academic experts. Results show that criteria relating with company and supplier selection factors are most important criteria

A Giga-Stable Oscillator with Hidden and Self-Excited Attractors: A Megastable Oscillator Forced by His Twin

In this paper, inspired by a newly proposed two-dimensional nonlinear oscillator with an infinite number of coexisting attractors, a modified nonlinear oscillator is proposed. The original system has an exciting feature of having layer−layer coexisting attractors. One of these attractors is self-excited while the rest are hidden. By forcing this system with its twin, a new four-dimensional nonlinear system is obtained which has an infinite number of coexisting torus attractors, strange attractors, and limit cycle attractors. The entropy, energy, and homogeneity of attractors’ images and their basin of attractions are calculated and reported, which showed an increase in the complexity of attractors when changing the bifurcation parameters

Methods for Refinement of Structural Finite Element Models: Summary of the GARTEUR AG14 Collaborative Programme

The finite element model is the main tool used by helicopter manufacturers for the analysis of helicopter structures and in particular for the prediction of vibration. High fidelity models that can accurately represent the structural dynamics are the key to producing effective low vibration designs. Helicopters with ‘jet’ smooth comfort are demanded by discriminating customers who also require ownership of vehicles with high reliability, low maintenance and reduced through life costs. The finite element model is an important tool in the assessment of aircraft modifications after the initial design and production when adverse vibration levels may become apparent. At this stage a structure is available and measured dynamic data from a shake test may be used to validate and improve the initial finite element model. The model derived from test data is not, by itself, comprehensive enough to allow the study and manipulation of the structural dynam-ics but its role in conjunction with the finite element model is a vital step towards improving the helicopter structural design. The main purpose of this GARTEUR collaboration was to explore methods and procedures for improving finite element models through the use of dynamic testing. For the foreseeable future it is expected that shake tests combined with finite element models will be the major tool for improving the dynamic characteristics of the helicopter structural design. It is there-fore of great importance to all participants that the procedure of validating and updating heli-copter finite element models is robust, rigorous and effective in delivering the best match based on realistic engineering adjustments to the finite element model. The industry need for finite element models, the variety of update procedures and their advan-tages are discussed in this paper together with some requirements for dynamic testing. The results of a systematic study on the model updating of a Lynx Mk7 airframe are presented and conclusions drawn. Recommendations are made with regard to performing subsequent dy-namic tests, model updating and for future collaborative study