Performance estimation method for in-service single-phase induction motors
This paper proposes a performance estimation method for single-phase induction motors in the field at any operating load using a set of data from in-service measurement. This paper describes the use of the improved equivalent circuit models based on double-revolving-field theory which a core loss element is properly added in order to provide more accurate results. The appropriate values for the model parameters can be evaluated by the use of measured data coupled with the genetic algorithms. The estimated performance result of several motors are presented and then compared to the measured values obtained from load tests, and clearly illustrate that agreement between the proposed method and the actual one is good.
An economical method for induction motor field efficiency estimation for use in on-site energy audit and management
This paper proposes an economical method that can help the plants to make right decision in replacing the inefficient induction motors with more efficient ones. This method focuses on the field efficiency of motors without the needs for removing motors and measuring the output power. The use of a few sets of measured data from field test coupled with the genetic algorithms for evaluating motor equivalent circuit instead of using the no-load and blocked-rotor tests is proposed. To illustrate how well the estimated efficiency matches that of calculated obtained from the standard evaluations, the results of various induction motors rating up to 100 hp are presented. Test results indicate that this method has a high accuracy, then it is suitable for conducting on-site energy audits of motors in order to project cost savings and payback and to support a confidence decision regarding the investment in higher efficiency motors.
Dawn or dusk of the 5th age of research in educational technology? A literature review on (e-)leadership for technology-enhanced learning in higher education (2013-2017)
The aim of this article is to establish the extent to which the concept of e-leadership has taken off as a lens through which to study leadership for technology-enhanced learning (TEL) in higher education. Building on a previous study conducted in 2013, this article thus covers an exploratory review of the literature for the period 2103-2017. It analyses 49 articles which explore both the specific concept of e-leadership as well as other work dealing more generally with leadership and organisational change for TEL in higher education. The findings show that while none of the empirical studies identified in the literature refer explicitly to e-leadership, there are a number of interesting insights to be found in the theoretical articles. The results also highlight the widely different interpretations and applications of the concept of e-leadership and the consequent need for the definition to be refined. The paper concludes with recommendations for further multidisciplinary research at the intersection of the fields of educational technology and educational management, focusing on values, strategy, organisation and leadership interactions at meso level, the economy and public policy at macro level, and teaching and learning at the micro level, as well as for research in Leadership Development for TEL.