Background and Objectives: With the increasing use of information technologies in the field of education, it is now possible to create flexible learning environments without temporal and spatial barriers on the Internet. These environments enable learners to access various learning materials, share their findings, and discuss with other online participants. Despite the dramatic increase in web-based courses and learners enrolling in these courses, there are many indications that the mentioned courses have failed to meet the needs of learners and learners remember unpleasant experiences from such contexts. One of the relatively new methods in teaching is flipped classroom. The underlying idea of the flipped classroom is that instructional materials are presented outside the classroom, and on the other hand, the classroom time is used for interaction and conceptual transformation. Also, the community of inquiry (CoI) framework created by Garrison et . (2001) has been extensively applied and explored. It is probably the most frequently used model based on technology for a constructivist learning design. According to Garrison et al, learners can learn collaboratively and as a group in an inquiry community when there is a shared cognitive, social, and teaching presence. learning experiences are formed through the interaction of cognitive presence, social presence, and teaching presence. Garrison et al. claim that the common nature of cognitive, social, and teaching presence leads to the creation of an inquiry community, in which a cooperative learning experience is created for learners. Therefore, the present study aimed to investigate the effect of using the flipped classroom on the learners’ perceived teaching, social and cognitive presence in online courses. Methods: This study was quasi-experimental in terms of research method, using pre-test and post-test design with experimental and control groups. The population of the research included all the students of Tehran in the academic year of 1400-1401, using Convenience sampling. A total of 58 people were selected and randomly assigned to the experimental group (30 students) and control group (28 students). Research instruments included CoI survey instrument developed by Arbaugh et al. (2008) along with rubric for online discussions analysis (Social presence: indicators by Rourke et . (1999), teaching presence: indicators by Anderson et al. (2001), and cognitive presence: indicators by Park (2009)). To analyze the data, descriptive statistics (mean, standard deviation), and inferential statistics, i.e., the multivariate analysis of covariance (MANCOVA), and the chi-squared test were used.Findings: The results of MANCOVA showed that the experimental group had better progress for all types of presence (teaching, social & cognitive) in posttest compared to the control group(p<0.05). Also calculated chi-square test showed that frequency of produced semantic units for all types of presence (teaching, social & cognitive) in the experimental group were significantly higher than those in the control group (p>0.05).Conclusion: The results of this research proved the potential of flipped classroom pedagogy in learner’s progress in the three key factors of the community of inquiry framework, i.e. cognitive, social and teaching presence. Also the findings of research can lead to the improvement of offered education in web-based courses and are useful for those who are involved designing and implementing web-based education.

When teaching in an e-learning environment, we are faced with a different and new environment compared to the face-to-face. Lack of teacher and learner physical presence in e-learning environments can turn into major problem in such courses, since, it has diverse effects on students' satisfaction, durability, and academic performance. Hence, the present study was conducted to investigate the Levels of teaching presence, cognitive presence and social presence as three components affecting the sense of presence in web-based courses at Shahid Beheshti University. The research method applied in this study was descriptive survey method. The statistical population included all students studying at Shahid Beheshti University in academic year 2019-2020. for this study, the sample size of 380 students in the master 's degree was selected from the available sampling method, which were 293 questionnaires analyzed. To answer the study questions, Friedman and Wilcoxon one-sample t-test and rank test were applied. One-sample t-test showed that the rate of all three components, namely, teaching, cognitive, and social presence was significantly lower than the mean average (p<0. 01), and therefore, at an unfavorable rate. According to Friedman rank test, the highest mean rank belonged to social presence and the lowest mean rank belonged to cognitive presence,teaching presence was in the second rank. There was a significant difference among the components of teaching, cognitive, and social presence (p<0. 01). Based on the results of Wilcoxon test, there was a significant difference between the rank of teaching presence and the ranks of cognitive and social presence, as well as between the ranks of cognitive and social presence (p<0. 01).

Introduction: During teaching in web-based learning environments, a new and different environment must be created compared to face-to-face environments. However, the lack of physical presence of teachers and learners in an online learning environment can turn into a major dilemma that can have adverse effects on learners' satisfaction and learning. So the aim of this study was to Investigating the relationship among educational, social and cognitive presences with students' academic performance in e-learning courses. . Methods: The the present research had a descriptive-correlational research design (causal model). The population of this study included all students enrolled in the web-based courses during the academic year 1396-1397 in tehran. a sample of 307 students at the postgraduate level were selected through cluster random sampling and responded to the Arbaugh et al(2008) Community of Inquiry framework survey instrument of which, 271 questionnaires could be analyzed. Data were analyzed using path analysis. Results: The results showed that the structural model of learner's academic performance in e-learning courses is a valid model and data are fitted with theoretical model (RMSEA = 0. 076). Based on this model, 48% of the variance in academic performance can be explained. Therefore, teaching presence on social presence, cognitive presence and academic performance, social presence on cognitive presence and academic performance and cognitive presence on academic performance have a significant direct effect. As a result, these factors can properly explain the academic performance of learners in the web-based courses. Conclusions: Accordingly, it is possible to improve the academic performance of learners by enhancing presence factors

Sluggish Cognitive Tempo is used to describe a particular type of attention deficit, concentration, and slowness in information processing. The aim of this study was to investigate the psychometric properties of the Sluggish Cognitive Tempo Scale (SCTS) of the parent form among Iranian children. The present study is a descriptive study. A sample of 1700 people was selected from the provinces of Tehran, East Azerbaijan, West Azerbaijan, Kurdistan, Fars and Khorasan using cluster sampling method. 122 subjects were excluded from statistical analysis due to incomplete answers to the questionnaires and thus the final sample was reduced to 1578 parents. The confirmatory factor analysis method and internal consistency were used to compute the Sluggish Cognitive Tempo Scale factorial validity and reliability, respectively. Also, in order to examine the construct validity of the Sluggish Cognitive Tempo Scale, we computed correlations between different dimensions of Sluggish Cognitive Tempo Scale with Attention Deficit Subscale of Mental Health Assessment Questionnaire for Children and Adolescents. The results of statistical results showed that this scale has structural validity, criterion and convergence in Iranian society. The results indicate that the scale is three factors and also the validity of the scale using Cronbach's alpha method and retest test after Approved two weeks. According to the findings of the present study, the parent form of the Sluggish Cognitive Tempo Scale (SCTS) has a good validity and reliability and it can be used in research related to slow cognitive multiplication in Iranian society.

The concept of social presence is defined as the ability of learners to identify the learning community, have a sense of belonging to the community and communicate purposefully in a learning community. The reason for emphasizing the social presence of online learning is that online and virtual learning experts believe that social constructivism is an important factor in promoting interpersonal communication and the quality of learning. Given the importance of social presence as an influential variable in the process of virtual education, it is necessary to pay more attention to this issue and its predictors. In this regard, the present study aimed to provide a causal model for predicting social presence based on cognitive presence mediated by the online learning atmosphere. Participants included 265 students of online courses of Payame Noor universities in North Khorasan province in the academic year of 2009-2010 who were selected by cluster random sampling method. In order to measure the research variables, questionnaires of cognitive presence, social presence and online learning atmosphere were used. Amos software and path analysis method were used to evaluate the proposed model. The results showed that, 1-According to the above findings, the proposed model in the RMSEA index (root mean square of estimation errors) does not fit well, so the model was modified by correlating latent variable errors and The results showed that the final model has a good fit,2-Cognitive presence has a direct, positive and significant relationship with social presence (P≤, 0. 05 and β, =0. 62),There is a direct, positive and significant relationship between cognitive presence and online learning (P≤, 0. 05 and β, = 0. 14) and also a direct relationship between online learning atmosphere and social presence is positive and significant (P≤, 0. 05 and β, =0. 32),3-In the indirect way, with the presence of mediator variables, the relationship between cognitive presence and social presence was still significant and the online learning atmosphere absorbs part of the effect of cognitive presence on social presence and mediates this relationship in part.

Performing the bacteriological tests for potable water is based on research, counting and discrimination of water pollution index (Coliform). In these methods doing the tests needs some preparation before sampling, during sampling and during transporting the samples to laboratory as well as during preparation of cultivation environment. The above mentioned tasks require much equipment and different stages of cultivation. In this project, the Presence-Absence method (P-A ), which examines the presence or absence of pollution index in water is compared to the multiple fermentation technique , which is being used in laboratories all around the country at present, also the replacement of method is evaluated. This project was performed during 3 months and 263 samples were examined by both methods. The results demonstrate 7.01% more sensitivity for P-A method to the other. Comparing quality and quantity of the two methods confirms more benefits for P-A method.

We address the throughput maximization problem for downlink transmission in DF-relay-assisted cognitive radio networks (CRNs) based on simultaneous wireless information and power transfer (SWIPT) capability. In this envisioned network, multiple-input multiple-output (MIMO) relay and secondary user (SU) equipment are designed to handle both radio frequency (RF) signal energy harvesting and SWIPT functional tasks. Additionally, the cognitive base station (CBS) communicates with the SU only via the MIMO relay. Based on the considered network model, several combined constraints of the main problem complicate the solution. Therefore, in this paper, we apply heuristic guidelines within the convex optimization framework to handle this complexity. First, consider the problem of maximizing throughput on both sides of the relay separately. Second, each side progresses to solve the complex problem optimally by adopting strategies for solving sub-problems. Finally, these optimal solutions are synthesized by proposing a heuristic iterative power allocation algorithm that satisfies the combinatorial constraints with short convergence times. The performance of the optimal proposed algorithm (OPA) is evaluated against benchmark algorithms via numerical results on optimality, convergence time, constraints’ compliance, and imperfect channel state information (CSI) on the CBS-PU link.

Community of Inquiry is a term that identifies the elements that are essential for the delivery of effective instruction (i.e., teaching presence, cognitive presence, and social presence). While it has been the subject of many studies in face-to-face settings, less attention has been accorded to it in online classes. This study was an attempt to investigate the relationship between Iraqi English as a foreign language (EFL) learners' community of inquiry and their attention to and engagement in online classes. To this end, 311 undergraduate students were selected from Basrah province in southern Iraq. The Google Form link for the community of inquiry scale as well as the online student engagement scale and sustained attention scale were shared among the participants via telegram and WhatsApp groups. The results of the Pearson correlation revealed that there was a significant relationship among the variables. A linear multiple regression analysis was conducted to identify the best predictor of the components of the community of inquiry for students' online engagement in and their attention to online classes. The results showed that social presence contributed more to the changes in learners' engagement in and attention to online classes. The findings of the study can encourage Iraqi EFL teachers to focus on specific aspects of community of inquiry to promote students' engagement and attendance in online classes.

AbstractThe aim of this study was to investigate the validity, reliability and factor structure of the "How I Think" questionnaire to assess cognitive distortions in Iranian students. The present research design is descriptive and psychometric studies. The statistical population of this study included all male high school students in city Dezful in the academic year 1399-1400, from which 316 students were selected by multi-stage random sampling and completed the How I think and Bass and Perry Aggression Questionnaires (for Convergent validity). Factor analysis, Cronbach's alpha and Pearson correlation were used to analyze the data using SPSS and AMOS 20 software. The results of factor analysis showed that the questionnaire consists of six factors and has good fit indices. The convergent validity of this questionnaire indicated a satisfactory correlation between the dimensions of the scale "How I think" with the Aggression Questionnaire (p <0.01). Cronbach's alpha and Split- half coefficients for the whole scale and its dimensions ranged from 0.66 to 0.92.The conclusion is that the Persian version of the "How do I think" questionnaire for measuring cognitive distortions in Iranian students has acceptable psychometric properties and can be used as a valid tool in research, educational and clinical situations.