Harmonic correction in power supplies feeding non-linear loads

This paper focuses on the design of an electronic circuit which can be used in conjunction with the power supplies used at the input of non-linear loads (computers, TV sets, etc.) in order to filter out the input current harmonics in such loads. The electronic circuit will fill the gaps of the distorted current waveform so that it becomes sinusoidal and also in phase with the mains supply. In this paper different configurations of the proposed electronic circuit are covered (depending on the location with respect to the non-linear load). An optimization algorithm is carried out in order to find the best location, minimum device rating for different type of loads. The proposed circuit monitors the input current, output voltage and power rating of the power supply. The circuit will then decide whether to filter the input current harmonics or the output voltage harmonics. The circuit will also optimize the best switching frequency for the required load so that the power supply operates at the maximum possible efficiency

The effect of corporate social responsibility on customer loyalty in mobile telephone companies

Purpose: The present study aims at developing and empirically testing a research model that presents the influence of Corporate Social Responsibility on corporate image, customer satisfaction and customer loyalty, demonstrating the direct and indirect effects among these structures. Design/Methodology/Approach: The examination of the proposed research model was carried out using a structured questionnaire completed by 358 mobile users in the city of Kavala. The validity and the reliability of the questionnaire were examined, while for the data analysis the Structural Equation Modeling Technique was used with LISREL 8.80. Findings: The findings of this study indicate that Corporate Social Responsibility have not a significant direct effect on customer loyalty, while corporate image and customer satisfaction have a significant positive effect on customer loyalty. Moreover, the findings provide practical new insights in understanding how a mobile company’s CSR policy could be developed and implemented to help enhance customer loyalty through the mediating effects of customer satisfaction. Practical Implications: The companies would like to understand the implications of its CSR policy implementation, especially in enhancing its corporate image and customer satisfaction in terms of reputation and impression. Originality/Value: This study is a pioneer research in addressing the mediating role played by customer satisfaction for strengthening the relationship between CSR and customer loyalty in mobile phone companies.peer-reviewe

Early X-ray emission from Type Ia supernovae originating from symbiotic progenitors or recurrent novae

One of the key observables for determining the progenitor nature of Type Ia supernovae is provided by their immediate circumstellar medium, which according to several models should be shaped by the progenitor binary system. So far, X-ray and radio observations indicate that the surroundings are very tenuous, producing severe upper-limits on the mass loss from winds of the progenitors. In this study, we perform numerical hydro-dynamical simulations of the interaction of the SN ejecta with circumstellar structures formed by possible mass outflows from the progenitor systems and we estimate numerically the expected numerical X-ray luminosity. We consider two kinds of circumstellar structures: a) A circumstellar medium formed by the donor star's stellar wind, in case of a symbiotic binary progenitor system; b) A circumstellar medium shaped by the interaction of the slow wind of the donor star with consecutive nova outbursts for the case of a symbiotic recurrent nova progenitor system. For the hydro-simulations we used well-known Type Ia supernova explosion models, as well as an approximation based on a power law model for the density structure of the outer ejecta. We confirm the strict upper limits on stellar wind mass loss, provided by simplified interpretations of X-ray upper limits of Type Ia supernovae. However, we show that supernova explosions going off in the cavities created by repeated nova explosions, provide a possible explanation for the lack of X-ray emission from supernovae originating from symbiotic binaries. Moreover, the velocity structure of circumstellar medium, shaped by a series of nova explosion matches well with the Na absorption features seen in absorption toward several Type Ia supernovae.Comment: 11 pages, 12 figures, submitted to MNRA

Modelling, safety verification and design of discrete/continuous processing systems.

Imperial Users onl

Factors affecting motivation in the public sector under the context of self-determination theory and public service motivation : the case of the Hellenic Agricultural Insurance Organization (H.A.I.O.)

Purpose: The main aim of this study is to develop and test a conceptual framework that explores the factors that motivate employees in public services. The study is based on two theories, the Self Determination Theory (SDT), and the Public Service Motivation (PSM). Design/methodology/approach: The empirical testing of the proposed conceptual framework was conducted using a structured questionnaire that was distributed to 390 employees of a Greek public sector organization, namely the Hellenic Agricultural Insurance Organization (Η.Α.Ι.Ο.). The population of the study consists of 489 public servants. Exploratory factor analysis, confirmatory factor analysis and the structural equation modeling (SEM) technique were used to test the research hypotheses. Findings: Results highlight, among others, the importance of work autonomy and job satisfaction and their impact on employees’ intrinsic motivation. Moreover, empirical results emphasize the need for building a supportive work environment that contributes on employee satisfaction, autonomy and relatedness. Results also confirm the existence of a positive relationship among intrinsic motivation, public service motivation and job performance. Practical implications: The findings suggest that in cases where external incentives are significantly limited (e.g., in the public sector), it is crucial to consider the importance of promoting and supporting intrinsic motivation and support public service incentives. Originality/value: Self-determination theory seems to be poorly explored in the Greek public sector, and moreover, in economies and countries with similar characteristics. Therefore, it seems crucial to increase the knowledge about the real value of self-determination theory as a work motivation approach, especially in the public sector. Finally, research results may help supervisors and business leaders to implement appropriate systems and practices that promote a supportive environment in the workplace.peer-reviewe

New design approaches to repurposing open educational resources for collaborative learning using mediating artefacts

In spite of high expectations and the support given by prestigious funding and educational institutions, Open Educational Resources (OER) have not been adopted widely by teachers and learners in practice. From a cultural historical activity theory perspective, we argue that Mediating Artefacts (MA) such as OER learning design visual representations and rich narrative pedagogical patterns may enable a more effective OER cycle of creation, design, use and evaluation. More specifically, two main arguments are analysed in this paper: first, that making the inherent design of OER more explicit will make them more understandable and hence reusable; second, that offering a small set of simple patterns will encourage new ways to interpret OER and inspire re-purposing in new challenging contexts. A series of successful workshops was carried out and qualitative data gathered which provide initial evidence that a set of CSCL pedagogical patterns were found very suitable in order to repurpose resources intended for individual use and adjust the focus to make them suit new collaborative learning contexts. Interpretation of the data will form the basis for further workshops that aim to extend the idea of using targeted mediating artefacts to guide the design and repurposing of OER