Australia’s Literacy and Numeracy Test for Initial Teacher Education Students: Trends in Numeracy for Low- and High-Achieving Students

The numeracy capabilities of pre-service teachers are a recent focus in the Australian educational system. In this article, we discuss findings from an analysis of data from the Literacy and Numeracy Test for Initial Teacher Education Students (LANTITE), which is administered by the Australian Council for Educational Research. In our analysis, we considered numeracy test data from 20 students from one Australian university: those who achieved the 10 highest and the 10 lowest overall numeracy scores in 2016 at this university on their first attempt of the test. We found that these groups clearly have particular characteristics that were linked to their success or failure on the numeracy test. We discuss programs and resources that the university has made available for students in preparation for the LANTITE and provide additional suggestions to support such students going forward

Nonlinear Control of Large Disturbances in Magnetic Bearing Systems

In this paper, the nonlinear operation of magnetic bearing control methods is reviewed. For large disturbances, the effects of displacement constraints and power amplifier current and di/dt limits on bearing control system performance are analyzed. The operation of magnetic bearings exhibiting self-excited large scale oscillations have been studied both experimentally and by simulation. The simulation of the bearing system has been extended to include the effects of eddy currents in the actuators, so as to improve the accuracy of the simulation results. The results of these experiments and simulations are compared, and some useful conclusions are drawn for improving bearing system robustness

On the pointwise completeness of differential-difference equations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34012/1/0000287.pd

Dynamic modeling of DC-DC converters with peak current control in double-stage photovoltaic grid-connected inverters

In photovoltaic (PV) double-stage grid-connected inverters a high-frequency DC-DC isolation and voltage step-up stage is commonly used between the panel and the grid-connected inverter. This paper is focused on the modeling and control design of DC-DC converters with Peak Current mode Control (PCC) and an external control loop of the PV panel voltage, which works following a voltage reference provided by a maximum power point tracking (MPPT) algorithm. In the proposed overall control structure the output voltage of the DC-DC converter is regulated by the grid-connected inverter. Therefore, the inverter may be considered as a constant voltage load for the development of the small-signal model of the DC-DC converter, whereas the PV panel is considered as a negative resistance. The sensitivity of the control loops to variations of the power extracted from the PV panel and of its voltage is studied. The theoretical analysis is corroborated by frequency response measurements on a 230 W experimental inverter working from a single PV panel. The inverter is based on a Flyback DC-DC converter operating in discontinuous conduction mode (DCM) followed by a PWM full-bridge single-phase inverter. The time response of the whole system (DC-DC + inverter) is also shown to validate the concept. Copyright © 2011 John Wiley & Sons, Ltd. In photovoltaic (PV) double-stage gridconnected inverters a high-frequency DC-DC isolation and voltage step-up stage is commonly used between the panel and the grid-connected inverter. This paper is focused on the modeling and control design of DC-DC converters with Peak Current mode Control (PCC) and an external control loop of the PV panel voltage, which works following a voltage reference provided by a maximum power point tracking (MPPT) algorithm. The sensitivity of the control loops to variations of the power extracted from the PV panel and of its voltage is studied. Copyright © 2011 John Wiley & Sons, Ltd. Copyright © 2011 John Wiley & Sons, Ltd.This work was supported by the Spanish Ministry of Science and Innovation (MICINN) under grant ENE2009-13998-C02-02. The company AUSTRIAMICROSYSTEMS co-financed this project.Garcerá Sanfeliú, G.; González Medina, R.; Figueres Amorós, E.; Sandía Paredes, J. (2012). Dynamic modeling of DC-DC converters with peak current control in double-stage photovoltaic grid-connected inverters. International Journal of Circuit Theory and Applications. 40(8):793-813. https://doi.org/10.1002/cta.756S793813408Carrasco, J. M., Franquelo, L. G., Bialasiewicz, J. T., Galvan, E., PortilloGuisado, R. C., Prats, M. A. M., … Moreno-Alfonso, N. (2006). Power-Electronic Systems for the Grid Integration of Renewable Energy Sources: A Survey. IEEE Transactions on Industrial Electronics, 53(4), 1002-1016. doi:10.1109/tie.2006.878356Kjaer, S. B., Pedersen, J. K., & Blaabjerg, F. (2005). A Review of Single-Phase Grid-Connected Inverters for Photovoltaic Modules. IEEE Transactions on Industry Applications, 41(5), 1292-1306. doi:10.1109/tia.2005.853371Ridley, R. B. (1991). A new, continuous-time model for current-mode control (power convertors). IEEE Transactions on Power Electronics, 6(2), 271-280. doi:10.1109/63.76813Femia, N., Petrone, G., Spagnuolo, G., & Vitelli, M. (2005). Optimization of Perturb and Observe Maximum Power Point Tracking Method. IEEE Transactions on Power Electronics, 20(4), 963-973. doi:10.1109/tpel.2005.850975Hua, C., & Lin, J. (2004). A modified tracking algorithm for maximum power tracking of solar array. Energy Conversion and Management, 45(6), 911-925. doi:10.1016/s0196-8904(03)00193-6Tan, Y. T., Kirschen, D. S., & Jenkins, N. (2004). A Model of PV Generation Suitable for Stability Analysis. IEEE Transactions on Energy Conversion, 19(4), 748-755. doi:10.1109/tec.2004.827707Femia, N., Petrone, G., Spagnuolo, G., & Vitelli, M. (2009). A Technique for Improving P&O MPPT Performances of Double-Stage Grid-Connected Photovoltaic Systems. IEEE Transactions on Industrial Electronics, 56(11), 4473-4482. doi:10.1109/tie.2009.2029589Chiu, H.-J., Huang, H.-M., Yang, H.-T., & Cheng, S.-J. (2008). An improved single-stage Flyback PFC converter for high-luminance lighting LED lamps. International Journal of Circuit Theory and Applications, 36(2), 205-210. doi:10.1002/cta.404Chiu, H.-J., Yao, C.-J., & Lo, Y.-K. (2009). A DC/DC converter topology for renewable energy systems. International Journal of Circuit Theory and Applications, 37(3), 485-495. doi:10.1002/cta.475Martins DC Demonti R Photovoltaic Energy Processing for Utility Connected System 1292 1296 10.1109/IECON.2001.975968www.focus.ti.com/lit/ml/slup127/slup127.pdf2003 http://www.fairchildsemi.comEsram, T., & Chapman, P. L. (2007). Comparison of Photovoltaic Array Maximum Power Point Tracking Techniques. IEEE Transactions on Energy Conversion, 22(2), 439-449. doi:10.1109/tec.2006.874230Liserre, M., Blaabjerg, F., & Hansen, S. (2005). Design and Control of an LCL-Filter-Based Three-Phase Active Rectifier. IEEE Transactions on Industry Applications, 41(5), 1281-1291. doi:10.1109/tia.2005.853373Liserre, M., Teodorescu, R., & Blaabjerg, F. (2006). Stability of photovoltaic and wind turbine grid-connected inverters for a large set of grid impedance values. IEEE Transactions on Power Electronics, 21(1), 263-272. doi:10.1109/tpel.2005.861185Figueres, E., Garcera, G., Sandia, J., Gonzalez-Espin, F., & Rubio, J. C. (2009). Sensitivity Study of the Dynamics of Three-Phase Photovoltaic Inverters With an LCL Grid Filter. IEEE Transactions on Industrial Electronics, 56(3), 706-717. doi:10.1109/tie.2008.2010175Ciobotaru M Teodorescu R Blaabjerg F Control of single-stage single-phase PV inverter P.1 P.10 10.1109/EPE.2005.219501Zmood, D. N., & Holmes, D. G. (2003). Stationary frame current regulation of PWM inverters with zero steady-state error. IEEE Transactions on Power Electronics, 18(3), 814-822. doi:10.1109/tpel.2003.810852Castilla, M., Miret, J., Matas, J., Garcia de Vicuna, L., & Guerrero, J. M. (2009). Control Design Guidelines for Single-Phase Grid-Connected Photovoltaic Inverters With Damped Resonant Harmonic Compensators. IEEE Transactions on Industrial Electronics, 56(11), 4492-4501. doi:10.1109/tie.2009.2017820Timbus A Teodorescu R Blaabjerg F Liserre M Synchronization methods for three phase distributed power generation systems 2474 2481 10.1109/PESC.2005.1581980Vorperian, V. (1990). Simplified analysis of PWM converters using model of PWM switch. II. Discontinuous conduction mode. IEEE Transactions on Aerospace and Electronic Systems, 26(3), 497-505. doi:10.1109/7.106127Reatti A Balzani M PWM switch model of a buck-boost converter operated under discontinuous conduction mode 667 670 10.1109/MWSCAS.2005.1594189Reatti, A., & Kazimierczuk, M. K. (2003). Small-signal model of PWM converters for discontinuous conduction mode and its application for boost converter. IEEE Transactions on Circuits and Systems I: Fundamental Theory and Applications, 50(1), 65-73. doi:10.1109/tcsi.2002.805709Lin, B.-R., Huang, C.-L., & Li, M.-Y. (2009). Novel interleaved ZVS converter with ripple current cancellation. International Journal of Circuit Theory and Applications, 37(3), 413-431. doi:10.1002/cta.480MIDDLEBROOK, R. D. (1975). Measurement of loop gain in feedback systems†. International Journal of Electronics, 38(4), 485-512. doi:10.1080/0020721750892042

Diseño de controladores para inversores monofásicos operando en modo isla dentro de una microrred

[ES] En este trabajo se presenta el diseño e implementación de tres controladores: control proporcional-integral, control proporcional-integral más controlador resonante y una nueva propuesta de control configurada con un control proporcional-integral + controlador proporcional más controlador resonante. El diseño de estos controladores está orientado a la operación de inversores en modo isla dentro del contexto de las microrredes, su rendimiento ha sido validado por medio de resultados de simulaciones y por medio de pruebas experimentales. Particularmente, la configuración de control propuesta presenta como ventaja respecto a los otros dos controladores, el evitar fenómenos de saturación que se presentan en los sistemas, los cuales ocurren cuando se presentan señales de control de gran amplitud. Además de mejorar el rechazo de perturbaciones que se presentan, cuando el inversor alimenta cargas lineales y no lineales. Es decir, con la combinación de ambos controladores, se consigue una solución adecuada para reducir la distorsión armónica total en la tensión de salida de un inversor monofásico, cuando se alimentan cargas en forma aislada o bien con el inversor desconectado de la red.Ortega, R.; Carranza, O.; Sosa, JC.; García, V.; Hernández, R. (2016). Diseño de controladores para inversores monofásicos operando en modo isla dentro de una microrred. Revista Iberoamericana de Automática e Informática industrial. 13(1):115-126. https://doi.org/10.1016/j.riai.2015.09.010OJS115126131Wu, D., Tang, F., Dragicevic, T., Vasquez, J. C., & Guerrero, J. M. (2014). Autonomous Active Power Control for Islanded AC Microgrids With Photovoltaic Generation and Energy Storage System. IEEE Transactions on Energy Conversion, 29(4), 882-892. doi:10.1109/tec.2014.2358612IEEE STD. 519-1992., 1993. IEEE Recommended Practices and Requirements for Harmonic Control in Electric Power Systems, IEEE Industry Applications Society/Power Engineering Society.Mikati, M., Santos, M., & Armenta, C. (2012). Modelado y Simulación de un Sistema Conjunto de Energía Solar y Eólica para Analizar su Dependencia de la Red Eléctrica. Revista Iberoamericana de Automática e Informática Industrial RIAI, 9(3), 267-281. doi:10.1016/j.riai.2012.05.010PSIM 7.0, 2006. Users Guide (2006), Powersim Inc.Sable, D.M.; Ridley, R.B.; Cho, B.H., 1990. Comparison of performance of single loop And current injection control for PWM converters which operate in both continuous and discontinuous modes of operation, Power Electronics Specialists Conference, 1990. PESC ’90 Record., 21st Annual IEEE, pp.74-79.Vorperian, V. (1990). Simplified analysis of PWM converters using model of PWM switch. Continuous conduction mode. IEEE Transactions on Aerospace and Electronic Systems, 26(3), 490-496. doi:10.1109/7.10612

On Euclidean Space And Function Space Controllability Of Control Systems With Delay.

PhDEngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/186908/2/7205020.pd