Requirement of green supply with higher quality has been consumers’ demand around the globe The electrical power system is expected to deliver undistorted sinusoidal rated voltage and current continuously at rated frequency to the consumers This paper presents a comprehensive review of signal processing and intelligent techniques for automatic classification of the power quality (PQ) events and an effect of noise on detection and classification of disturbances It is intended to provide a wide spectrum on the status of detection and classification of PQ disturbances as well as an effect of noise on detection and classification of PQ events to the researchers, designers and engineers working on power quality More than 150 research publications on detection and classification techniques of PQ disturbances have been critically examined, classified and listed for quick reference

A critical review of detection and classification of power quality events

Structured knowledge processes and firm performance: The role of organizational agility

Changing clinical practice is a difficult process, best illustrated by the time lag between evidence and use in practice and the extensive use of low-value care. Existing models mostly focus on the barriers to learning and implementing new knowledge. Changing clinical practice, however, includes not only the learning of new practices but also unlearning old and outmoded knowledge. There exists sparse literature regarding the unlearning that takes place at a physician level. Our research objective was to elucidate the experience of trying to abandon an outmoded clinical practice and its relation to learning a new one. We used a grounded theory-based qualitative approach to conduct our study. We conducted 30-min in-person interviews with 15 primary care physicians at the Cleveland VA Medical Center and its clinics. We used a semi-structured interview guide to standardize the interviews. Our two findings include (1) practice change disturbs the status quo equilibrium. Establishing a new equilibrium that incorporates the change may be a struggle; and (2) part of the struggle to establish a new equilibrium incorporating a practice change involves both the “evidence” itself and tensions between evidence and context. Our findings provide evidence-based support for many of the empirical unlearning models that have been adapted to healthcare. Our findings differ from these empirical models in that they refute the static and unidirectional nature of change that previous models imply. Rather, our findings suggest that clinical practice is in a constant flux of change; each instance of unlearning and learning is merely a punctuation mark in this spectrum of change. We suggest that physician unlearning models be modified to reflect the constantly changing nature of clinical practice and demonstrate that change is a multi-directional process.

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The physician’s experience of changing clinical practice: a struggle to unlearn

组织去学习（Organizational Unlearning）概述

Phasor frequency, magnitude, and angle describing a sinusoidal signal are widely used as critical variables in algorithms and performance indices in many power system applications, such as the protection relaying and state monitoring This paper proposes a novel approach for estimating the phasor parameters, namely frequency, magnitude, and angle in real time based on a newly constructed recursive wavelet transform This algorithm is capable of estimating the phasor parameters in a quarter cycle of an input signal It features fast response and achieves high accuracy over a wide range of frequency deviations The signal sampling rate and data window size can be selected to meet desirable applications requirements, such as fast response, high accuracy, and low computational burden Besides, an approach for eliminating a decaying dc component, which has a significant impact on estimating phasors, is proposed by using a recursive wavelet transform Simulation results demonstrate that the proposed methods achieve good performance

Real-Time Power System Frequency and Phasors Estimation Using Recursive Wavelet Transform

A new method for the measurement of the instantaneous power-system frequency is proposed. It is based on the frequency estimation of the voltage signal using three equidistant samples. An algorithm is developed that diminishes the variance of the estimation. The procedure is applied to the case of single- and three-phase networks, and uncertainty in the frequency estimation is obtained with simulated signal and severe conditions of signal quality. A frequency variation has been assumed as plusmn2 Hz around the nominal value, with a maximum rate of change of 1 Hz/s. The uncertainty of 25 mHz and 3.5 mHz has been obtained for single- and three-phase signals, respectively. A low-cost virtual instrument has been developed to make frequency measurements over the actual voltage signal.

Power System Frequency Measurement Under Nonstationary Situations

Purpose – The Spanish hospitality industry is facing environmental challenges which require organisations and individuals to learn new skills and practices and create new environmental knowledge. The aim of this paper is to analyse the relationships between an unlearning context and environmental knowledge.Design/methodology/approach – This paper analyses the relationships between an unlearning context and environmental knowledge and tries to identify whether environmental knowledge impacts on business outcomes through an empirical study of 127 Spanish hospitality companies.Findings – The results support the hypothesis that, in order to create environmental knowledge and hence foster the application of new environmental knowledge, companies need to provide and support an unlearning context.Research limitations/implications – It is important that managers provide an appropriate unlearning context to support the openness of individuals to new ideas and environmental awareness.Originality/value – This study ...

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Environmental knowledge, unlearning, and performance in hospitality companies

A single indicator [i.e., the power quality factor (PQF)] in the range between 0 and 1 is suggested in this paper to integrally reflect the power transfer quality of a general three-phase network feeding unbalanced nonlinear loads. The prominent power quality aspects considered in the paper are the following: 1) the voltage and current harmonic levels; 2) the degree of unbalance; and 3) the phase displacement factor in the different phases at the fundamental frequency. A network that supplies balanced sinusoidal currents at balanced sinusoidal voltages with zero phase displacement between the corresponding currents and voltages yields a PQF of unity. The measurement of the PQF is discussed. Practical examples illustrate the use and relevance of the new quality factor.

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J. Gutierrez

Papers

Power System Frequency Measurement Under Nonstationary Situations

Environmental knowledge, unlearning, and performance in hospitality companies

Power Quality Factor for Networks Supplying Unbalanced Nonlinear Loads

Linking an unlearning context with firm performance through human capital

Linking unlearning with quality of health services through knowledge corridors