RiPLE: Recommendation in Peer-Learning Environments Based on Knowledge Gaps and Interests

Various forms of Peer-Learning Environments are increasingly being used in post-secondary education, often to help build repositories of student generated learning objects. However, large classes can result in an extensive repository, which can make it more challenging for students to search for suitable objects that both reflect their interests and address their knowledge gaps. Recommender Systems for Technology Enhanced Learning (RecSysTEL) offer a potential solution to this problem by providing sophisticated filtering techniques to help students to find the resources that they need in a timely manner. Here, a new RecSysTEL for Recommendation in Peer-Learning Environments (RiPLE) is presented. The approach uses a collaborative filtering algorithm based upon matrix factorization to create personalized recommendations for individual students that address their interests and their current knowledge gaps. The approach is validated using both synthetic and real data sets. The results are promising, indicating RiPLE is able to provide sensible personalized recommendations for both regular and cold-start users under reasonable assumptions about parameters and user behavior.Comment: 25 pages, 7 figures. The paper is accepted for publication in the Journal of Educational Data Minin

Cosmic Strings Collision in Cosmological Backgrounds

The collisions of cosmic strings loops and the dynamics of junctions formations in expanding backgrounds are studied. The key parameter controlling the dynamics of junctions formation, the cosmic strings zipping and unzipping is the relative size of the loops compared to the Hubble expansion rate at the time of collision. We study analytically and numerically these processes for large super-horizon size loops, for small sub-horizon size loops as well as for loops with the radii comparable to the Hubble expansion rate at the time of collision.Comment: 24 pages, 13 figure

Zipping and Unzipping of Cosmic String Loops in Collision

In this paper the collision of two cosmic string loops is studied. After collision junctions are formed and the loops are entangled. We show that after their formation the junctions start to unzip and the loops disentangle. This analysis provides a theoretical understanding of the unzipping effect observed in numerical simulations of a network of cosmic strings with more than one type of cosmic strings. The unzipping phenomena have important effects in the evolution of cosmic string networks when junctions are formed upon collision, such as in a network of cosmic superstrings.Comment: references added, typos corrected, PRD versio

Studying the brands in Iranian apparel industry: comparing GERAD agency in Iran with other agents in Qom

Today, one can consider apparel industry as one of the most preliminary profession needed by human beings. In terms of brand, the industry enjoys good situation in the world. Brand and trademark issues are admired as a competitive advantage worldwide. Due to brand role in promoting, growing and progressing the products both qualitatively and quantitatively, it is accepted and used in all Iranian industries. Its importance in competition, the growth and development of companies and analyzing business environment has made attractive. Present paper aims at studying the status of brands in Iranian apparel industry (Comparing GERAD agency in Iran with other agents in Qom) by using PEST method, SWOT analysis, CCFs and target market segmentation matrix. Based on conducted investigations to identify current barriers and challenges in apparel industry brands through interviews with senior managers of active companies in apparel and textile industry and a questionnaire submitted to them, 13 proper guidelines were achieved among which deregulation of prices strategy as well as four suggestion on trust building and promoting national and Iranian brands in domestic, regional and global markets were provided

Improvement of Starting Transient State in a Fixed Speed Wind Turbine using STATCOM

Nowadays, the effects of wind generators have become an important issue in power quality due to impressionability in the lack of uniformity in adjusting frequency and power systems’ voltage. Wind turbine generators during commissioning even when they use a soft starter and connect to a power network transient and oscillatory flow have reactive power and effective voltage. With the presence FACTS devices (especially parallel devices) and reactive power injection, reactive power changes and effective voltage can be reduced. In this paper, the studied system consists of Thévenin equivalent circuit of a power network, which connects to a wind generator through transformers and transmission lines. Dynamic modeling of transient wind turbine and also, commissioning condition of power system model and simulation of computer were done in PSCAD / EMTDC software. At the end, simulation results of the desired system show that the presence of STATCOM in network improves the initial transient state of some parameters such as voltage, reactive power output of generators and etc

Multilevel Visualisation of Topic Dependency Models for Assessment Design and Delivery: A Hypergraph Based Approach

The effective design and delivery of assessments in a wide variety of evolving educational environments remains a challenging problem. Proposals have included the use of learning dashboards, peer learning environments, and grading support systems; these embrace visualisations to summarise and communicate results. In an on-going project, the investigation of graph based visualisation models for assessment design and delivery has yielded promising results. Here, an alternative graph foundation, a two-weighted hypergraph, is considered to represent the assessment material (e.g., questions) and their explicit mapping to one or more learning objective topics. The visualisation approach considers the hypergraph as a collection of levels; the content of these levels can be customized and presented according to user preferences. A case study on generating hypergraph models using commonly available assessment data and a flexible visualisation approach using historical data from an introductory programming course is presentedComment: Published in the proceedings of the 25th International DMS Conference on Visualization and Visual Language

Distribution of Optimum Reactive Power in the Presence of Wind Power Plant and considering Voltage Stability Margin using Genetic Algorithm and Monte Carlo methods

Network reactive power resources are important factors affecting voltage stability that somehow can have effect on safety margin of system voltage stability. In this study, question of relationship between distribution of optimum reactive power and voltage stability margin in presence of wind power plant has been performed. For this reason, to minimize the reactive power costs due to the synchronous generator, synchronous condenser and the capacitor bank and also given the importance maximization the voltage stability margin and considering equality and inequality constraints, has been used from a nonlinear programming method. In here, problem by using Genetic Algorithm in order to minimize cost of reactive power and with considering the voltage stability margin based on Monte Carlo simulation method. In MATLAB software has been optimized. Problem simulation over 30-bus network has been solved for two state low load and full load and with two scenarios was run and analyzed

Examining links between students’ mental imagistic abilities and their perceptions of chemical representations

It is a long-held pervasive belief that for a student to gain expertise in chemistry, they must be able to mentally visualise molecular phenomena (Zare, 2002; Kozma & Russell, 2005; Gkitzia et al., 2020). In recent years however the term “aphantasia” has been popularised to describe individuals lacking visual mental imagery and is believed to characterise 2-5% of the population (Zeman et al., 2015). Furthermore, research has been conducted to explore and understand the distinction between ‘visual’ and ‘spatial’ imagery (Blazhenkova, 2016; Pounder et al., 2021). Those who can visualise images typically associate visual mental imagery with spatial mental manipulations, yet paradoxically aphantasia has been found to be overrepresented in math and science occupations (Zeman, 2021). As part of a research higher degree project, several research questions are under consideration: Do students with and without visual imagery perform differently in chemistry related tasks? How do students without visual imagery solve problems that are ‘normally’ achieved using it? Is a bias towards teaching methods that utilise visual imagery detrimental to students that lack it? Should instructors move away from the notion that it is essential for students to be able to create visual mental models? Or instead, would it be necessary to provide additional support for those who cannot? In this presentation the findings from a pilot study addressing several of the above questions will be discussed. I will examine some specific outcomes from the performance of 18 first-year chemistry students who possessed a range of visualisation abilities as they completed eight tasks related to chemistry and visualisation. I will also discuss how my findings intend to guide the future of the project. REFERENCES Blazhenkova, O. (2016). Vividness of object and spatial imagery. Perceptual and Motor Skills, 122 (2), 490-508. Kozma, R. & Russell, J. (2005). Students Becoming Chemists: Developing Representationl Competence. In: Gilbert, J.K. (eds) Visualization in Science Education. Models and Modeling in Science Education, vol 1. Springer, Dordrecht. https://doi.org/10.1007/1-4020-3613-2_8 Gkitzia, V.,  Salta, K., & Tzougraki, C. (2020). Students’ competence in translating between different types of chemical representations. Chemistry Education Research and Practice, 21(1), 307-330. Pounder, Z., Jacob, J., Evans, S., Loveday, C., Eardley, A., & Silvanto, J. (2021). Individuals with congenital aphantasia show no significant neuropsychological deficits on imagery-related memory tasks. https://doi.org/10.31234/osf.io/gqayt Zare, R. N. (2002). Visualizing chemistry. Journal of Chemical Education, 79(11), 1290. Zeman, A. Z.,  Dewar, M., & Della Sala, S. (2015). Lives without imagery-Congenital aphantasia. Cortex, 73, 378-380. Zeman, A. (2021). Blind Mind's Eye. American Scientist Magazine, 109(2), 110-117