Self-induced structure in the current-voltage characteristics of RSQUIDs

Resistive two-junction SQUIDs (RSQUIDs) made from high-temperature superconductors are being developed as narrow-linewidth tunable oscillators in the GHz frequency range. We present here the results of numerical simulation of RSQUIDs of this type. These studies have identified conditions where sub-harmonic steps and other features are apparent in the current-voltage characteristics, driven by the internally-generated heterodyne frequency. The behavior is sensitive to the frequency (set by the voltage across the resistive element in the RSQUID), the temperature and also the loop inductance. We have studied the effects of thermal noise on these features. We also assess how these effects might be observed, and consider how they might affect practical applications of high frequency heterodyne RSQUID oscillators

Simulation and measurement of hts josephson heterodyne oscillator

We report continuing investigations into practical applications of the ac Josephson effect as the basis for a voltage-tunable radio-frequency oscillator. We have previously demonstrated experimentally that useful power levels (10 s of nW) and linewidths of a few kHz can be achieved in the heterodyne output from a High-Temperature-Superconducting Resistive SQUID (HTS-RSQUID) operating in the frequency range 1-50 MHz. Those results were achieved with 2-junction R-SQUIDs incorporating current-biased shunt resistors of a few micro-ohms. We have now modified the fabrication procedures, and adjusted the shunt resistors and bias current values so that higher frequencies can be achieved. The Josephson junctions are of step-edge type, rather than the bi-crystal type used in our earlier work. The step-edge technique permits much more flexibility in the geometrical lay-out and utilizes the more cost-effective single-crystal MgO substrates. In the present paper, we report numerical simulations and experimental measurements on these devices in the frequency range up to 2 GHz

Experimental study of the vortex system generated by a Formula 1 front wing

This thesis describes the research undertaken on the behaviour of the vortex system generated by a Formula 1 front wing, as it travels about a rotating wheel. This has been realised by investigating the flow structure downstream of a 50% wind tunnel model using flow visualisation, total pressure wake surveys, hot-film anemometry and PIV. The characteristics of the vortex system have been obtained by examining the flow from the wing and endplate without the wheel. This has shown that the wake consists of four co-rotating vortices which interact and merge together. By modifying the ride height of the wing the relative strengths of the vortices are affected resulting in subtle differences to the downstream merging process. The introduction of the wheel substantially affects the vortex system. To analyse its influence the behaviour of a single trailing vortex has been examined as it passes about the wheel. Observations have shown that the trajectory of the vortex is strongly dependant on its initial position and strength ahead of the wheel. With the wheel included, the flow structure generated by the Formula 1 front wing is dominated by the interaction between two vortices. The relative strength and separation of these two structures is affected by both the ride height of the wing and the influences of the rotating wheel. As a result the flow structure formed downstream is dependant on the amount of merging which has taken place. This research has shown that the flow downstream of a Formula 1 front wing is strongly affected by the merging characteristics of the trailing vortex system. Hence by careful consideration of the placement and strength of the vortices it is possible to change the structure of the flow.Open Acces

Web 2.0 tools in the EFL classroom: Comparing the effects of Facebook and blogs on L2 writing and interaction

[EN] Web 2.0 technologies have become an integral part of our lives, transforming not only how we communicate with others, but also how language is taught and learned in the L2 classroom. Several studies have looked into the use of these tools and how they influence L2 learning (e.g. Jin, 2015; Wang & Vásquez, 2014), yet only one has compared the effects of two Web 2.0 technologies (Castaneda Vise, 2008). Thus, the aim of this study was to compare the impact that Facebook and blogs had on the writing skills, namely, writing fluency, lexical richness, and syntactic complexity, of Japanese EFL learners. Moreover, the authors examined the influence blogging and Facebook had on interaction, i.e., the number of comments the learners posted outside of class. Student attitudes towards using these tools for written English were also measured through a survey based on the technology acceptance model (Davis, 1989). Twenty-three students at a Japanese university participated in the study and were divided into a Facebook group (n = 14) and a blog group (n = 9) according to their classes. Both groups took part in a ten-week treatment consisting of weekly guided free-writings on their respective Web 2.0 applications. Pre- and post-tests were administered and non-parametric statistical tests were used to determine if any significant writing gains were made. It was found that students in both blogging and Facebook groups showed similar improvements in writing skills. However, blogging seemed to be more effective at promoting interaction and students who took part in this group retained more favorable attitudes on using blogging for L2 writing. It was concluded that Facebook may indeed present an environment where students can be distracted from more formal educational pursuits (e.g. Wang & Kim, 2014) even when they are in private Facebook groups, while blogging may support a more serious environment for improving L2 writing skills.Dizon, G.; Thanyawatpokin, B. (2018). Web 2.0 tools in the EFL classroom: Comparing the effects of Facebook and blogs on L2 writing and interaction. The EuroCALL Review. 26(1):29-42. doi:10.4995/eurocall.2018.7947SWORD2942261Alm, A. (2015). Facebook for informal language learning. EUROCALL Review, 23(2), 3-18. Retrieved from http://polipapers.upv.es/index.php/eurocall/article/view/4665/4791Amir, Z., Ismail, K., Hussin, S. (2011). Blogs in language Learning: Maximizing Students' Collaborative Writing. Procedia Social and Behavioral Sciences, 18, 537-543. doi: 10.1016/j.sbspro.2011.05.079Browne, C. (2013). The new general service list: Celebrating 60 years of vocabulary learning. The Language Teacher, 37(4), 13-16.Castaneda Vise, D. A. (2008). The effects of wiki- and blog-technologies on the students' performance when learning the preterit and imperfect aspects in Spanish. Dissertation Abstracts International: Section A. The Humanities and Social Sciences, 69 (01), 0187.Crook, C. (2008). Web 2.0 Technologies for Learning: The Current Landscape - Opportunities, Challenges and Tensions. Retrieved fromhttp://dera.ioe.ac.uk/1474/1/becta_2008_web2_currentlandscape_litrev.pdfDavis, F. D. (1989). Perceived usefulness, perceived ease of use, and user acceptance of information technology. MIS Quarterly, 13(3), 319-340. Retrieved from jstor.org/stable/249008Dizon, G. (2016). A comparative study of Facebook vs. paper-and-pencil writing to improve L2 writing skills. Computer Assisted Language Learning, 29(8), 1249-1258. doi: 10.1080/09588221.2016.1266369Fellner, T., Apple, M. (2006). Developing writing fluency and lexical complexity with blogs. The JALT CALL Journal, 2(1), 15-26.George, D., & Mallery, P. (2003). SPSS for Windows step by step: A simple guide and reference (4th ed.). Boston, MA: Allyn & Bacon.Hammond, L. (1991). Using focused freewriting to promote critical thinking. In P. Belanoff, P. Elbow, & S. Fontaine (Eds.), Nothing begins with N: New investigations of freewriting (pp. 71-92). Carbondale, IL: Southern Illinois University.Harrison, R., & Thomas, M. (2009). Identity in online communities: social networking sites and language learning. International Journal of Emerging Technologies and Society, 7(2), 109-124.Hashimoto, K. (2012). Exploring the relationship between L2 blogging, learner autonomy, and L2 proficiency levels: A case study of post-secondary Japanese L2 learners (Doctoral dissertation). Retrieved from Proquest, UMI Dissertations Publishing.Hwang, J. A. (2010). A case study of the influence of freewriting on writing fluency and confidence of EFL college-level students. Second Language Studies, 28(2), 97-134. Retrieved fromhttp://www.hawaii.edu/sls/wp-content/uploads/2014/09/Hwang.pdfJin, S. (2015). Using Facebook to promote Korean EFL learners' intercultural competence. Language, Learning & Technology, 19(3), 38-51. Retrieved fromhttp://llt.msu.edu/issues/october2015/action2.pdfKabilan, M. K., Ahmad, N., & Abidin, M. J. Z. (2010). Facebook: An online environment for learning of English in institutions of higher education? Internet and Higher Education, 13, 179-187. doi: 10.1016/j.iheduc.2010.07.003Kissau, S., McCullough, H., Pyke, J. G. (2010). 'Leveling the playing field:' The effects of online second language instruction on student willingness to communicate in French. CALICO Journal, 27(2). 277-297. doi: 10.11139/cj.27.2.277-297Laufer, B., & Nation, P. (1995). Vocabulary size and use: Lexical richness in L2 written production. Applied Linguistics, 16, 307-322. doi:10.1093/applin/16.3.307Lee, Y., Kozar, K. A., & Larsen, K. R. T. (2003). The technology acceptance model: Past, present, and future. Communications of the Association for Information Systems, 12, 752-780. Retrieved from aisel.aisnet.org/cais/vol12/iss1/50Levy, M., & Stockwell, G. (2006). CALL Dimensions: Options and issues in CALL. Lawrence Erlbaum: Mahwah, NJ.Mills, N. (2011). Situated learning through social networking communities: The development of joint enterprise, mutual engagement, and a shared repertoire. CALICO Journal, 28(2), 345-368. doi: 10.11139/cj.28.2.345-368Mitchell, K. (2010). A social tool: Why and how ESOL students use Facebook. CALICO Journal, 29(3), 471-493. doi: 10.11139/cj.29.3.471-493.Miyazoe, T., Anderson, T. (2009). Learning outcomes and students' perceptions of online writing: Simultaneous implementation of a forum, blog, and wiki in an EFL blended learning setting. System, 38, 185-199.Montero-Fleta, B., & Perez-Sabater, C. (2010). A research on blogging as a platform to enhance language skills. Procedia Social and Behavioral Sciences, 2, 773-777. doi: 10.1016/j.sbspro.2010.03.100Moore, K. & Iida, S. (2010). Students' perception of supplementary, online activities for Japanese language learning: Groupwork, quiz and discussion tools. Australasian Journal of Educational Technology, 26(7), 966-979. Retrieved from http://www.ascilite.org.au/ajet/ajet26/moore.htmlNakatsukasa, K. (2009). The efficacy and students' perceptions of collaborative blogging in an ESL classroom. In Chapelle, C.A., Jun, H.G., Katz, I (Eds.), Developing and evaluating language learning materials (pp. 69-84). Ames, IA: Iowa State University.Nation, I. S. P. (1989). Improving speaking fluency. System, 17, 377-384. doi: 10.1016/0346-251X(89)90010-9Nepomuceno, M. (2011). Writing Online: Using Blogs as an Alternative Writing Activity in Tertiary ESL Classes. TESOL Journal, 5, 92-105.Pegrum, M. (2009). Communicative networking and linguistic mashups on Web 2.0. In M. Thomas (Ed.), Handbook of research on Web 2.0 and second language learning (pp. 20-41). IGI Global.Pinkman, K. (2005). Using Blogs in the Foreign Language Classroom. The JALT CALL Journal. 1(1), 12-24.Robinson, P. (2001). Task complexity, task difficulty, and task production: Exploring interaction in a componential framework. Applied Linguistics, 22(1), 27-57. doi: 10.1093/applin/22.1.27Shih, R. C. (2011). Can Web 2.0 technology assist college students in learning English writing? Integrating Facebook and peer assessment with blended learning. Australasian Journal of Educational Technology, 27(5), 829-845. Retrieved from https://eric.ed.gov/?id=EJ943540Sykes, J. M., Oskoz, A., & Thorne, S. L. (2008). Web 2.0, Synthetic Immersive Environments, and Mobile Resources for Language Education. CALICO Journal, 25(3), 528-546.Tu, C., Blocher, M., & Ntoruru, G. (2008). Constructs for Web 2.0 learning environments: A theatrical metaphor. 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Simulation of HTS Josephson Mixers

© 2016 IEEE. The Commonwealth Scientific and Industrial Research Organization has developed superconducting microwave monolithic integrated circuit (MMIC) mixers using step-edge Josephson junctions and on-chip filters, made from YBaCuO on MgO substrates. Integration into an MMIC results in a compact and efficiently coupled structure. These have been shown to have outstanding conversion efficiency, dynamic range, and linearity. We report here a range of simulations of this type of mixer. We have mainly used Josephson simulators and analyze the data in both the time and frequency domains. More recently, we have also used microwave simulators incorporating a novel Verilog-A Josephson junction model that we have developed. We have looked at the interactions of junction bias current, local oscillator power, and radio-frequency input power with conversion efficiency, dynamic range, and linearity. Good agreement is found overall with measurements

An evaluation of the integration of m-learning in Total Reading Approach for Children Plus (TRAC+): Enhancing literacy of early grade students in Cambodia.

The Total Reading Approach for Children (TRAC) project was first implemented in Cambodia from 2013 to 2014 by World Education, Inc. (WEI) to improve early grade reading outcomes among Grade 1 and Grade 2 students. This was made possible through a grant from All Children Reading: A Grand Challenge for Development (ACR GCD). ACR GCD, which was launched in 2011 by the United States Agency for International Development (USAID), World Vision, and the Australian Government, is an ongoing series of competitions that leverages science and technology to source, test, and disseminate scalable solutions to improve the literacy skills of early grade learners in developing countries. End-of-project assessments of TRAC were encouraging: over 90% of performance indicators were successfully achieved. As a result, WEI was awarded follow-on funding by World Vision International – Cambodia to scale up TRAC. Called TRAC Plus (TRAC+), the scale up rolled out in 13 World Vision area development programs in five provinces in Cambodia in December 2014. In Year 1, TRAC+ ran in 170 schools, and continued to work in 138 of the 170 original target schools in Year 2. By the end of the project in September 2017, TRAC+ had directly reached about 20,000 students. This report presents the findings of an independent evaluation of TRAC+ conducted from February to September 2017 by Dr. Grace Oakley, Dr. Mark Pegrum, and Dr. Thida Kheang—all from the Graduate School of Education, The University of Western Australia—assisted by Cambodian researcher Mr. Krisna Seng. The primary focus of the evaluation was the m-learning component of TRAC+—the use of Aan Khmer, a game-based app developed with funding from ACR GCD to teach Khmer alphabetical principles, vocabulary, and fluency in low resource environments. The evaluation set out to answer the question, “How and to what extent does the integration of m-learning in TRAC+ enhance the literacy of early grade students?” The findings of this study contribute to the body of knowledge on the effectiveness, sustainability, and scalability of m-learning integrated into TRAC+ in the Cambodian primary school context. Equity and efficiency issues were also addressed. This evaluation was conducted under the Digital Learning for Development (DL4D) project of the Foundation for Information Technology Education and Development (FIT-ED) of the Philippines. As part of the Information Networks in Asia and Sub-Saharan Africa (INASSA) program of the International Development Research Centre (IDRC) of Canada and the Department for International Development (DFID) of the United Kingdom, DL4D aims to improve educational systems in developing countries in Asia through testing digital learning innovations and scaling proven ones. Funding for the evaluation was provided jointly by DL4D and ACR GCD.This research was conducted under the Digital Learning for Development (DL4D) project of the Foundation for Information Technology Education and Development (FIT-ED) of the Philippines, jointly funded by the International Development Research Centre (IDRC) of Canada, the Department for International Development (DFID) of the United Kingdom, and All Children Reading: A Grand Challenge for Development (ACR GCD)—a partnership of United States Agency for International Development (USAID), World Vision, and the Australian Government