bluuebunny/crossref_metadata_2025_split huggingface dataset:
An efficient algorithm of transient responses on wind turbine towers struck by lightning
Authors: Xiaohui Wang , Xiaoqing Zhang , Dasheng Yang 
Published: February 2009

PurposeThe purpose of this paper is to propose an efficient algorithm for computing the transient responses on wind turbine (WT) towers struck by lightning.Design/methodology/approachThe tower is modeled as an electric network and a set of formulas are given for calculating the related electrical parameters. The parameters of grounding rods are also proposed. Based on the numerical representation of the transient characteristics of inductive elements, the electric network is converted into an equivalent circuit. The transient responses are obtained from the equivalent circuit by using circuit analysis method.FindingsThe calculated results are in good agreement with results computed by a hybrid method in frequency and time domain, which demonstrating the validity of the proposed method.Originality/valueThe transient responses on WT towers struck by lightning are computed using the numerical calculation method directly in time domain and electric field, electromagnetic field and induced potentials will be computed from the responses directly, which can provide guidelines for lightning protection design.
Optimum regulation of DC sources in cascaded multi‐level inverters
Authors: Fathi S.H. , Hosseini Aghdam M.G. , Zahedi A. , Gharehpetian G.B. 
Published: February 2009

PurposeThe purpose of this paper is to introduce a new concept in selecting the values of the DC source voltages in cascaded multi‐level inverters in order to improve the output voltage THD.Design/methodology/approachIn cascaded multi‐level inverters, it is usually assumed that the DC sources have the same constant voltage and output harmonics minimization is accomplished by applying proper switching angles. Employing different DC voltages with proper ratios can result in further reduction of the harmonics. After formulation of the system, i.e. describing the inverter's output voltage components in terms of the switching angles and unequal DC source voltages, a rule is applied to obtain the step heights of the staircase output waveform (DC source voltages), so that the output waveform becomes as close to the required fundamental sine wave as possible. Substituting the obtained DC source voltages into the harmonics elimination equations results in a set of equations, which are functions of switching angles only. Solving these equations leads to proper switching angles, which, regardless of the fundamental component's value, provide the specified harmonic conditions. The output voltage is then controlled by DC sources voltage regulation.FindingsComputer simulations show that employing the proposed concept results in substantial improvement in the harmonic minimization, as well as, extending the operating range of the inverter, compared to the conventional methods with equal DC source voltage multi‐level inverters.Originality/valueThe proposed concept according to which the ratio of the DC source voltages are determined, is original.
A new model for a safety analysis in a system of earthing systems interconnected through bare‐buried conductors
Authors: Zizzo Gaetano , Campoccia Angelo , Riva Sanseverino Eleonora 
Published: February 2009

PurposeThe purpose of this paper is to present a mathematical model for studying the effects of the interconnection through bare‐buried conductors (BBC) of the secondary substations' earthing system of an urban area.Design/methodology/approachThe developed methodology is based on three main points: the solution of the transmission lines' equations for the formulation of a lumped parameters model of a BBC considering the conductive effect; the division of the distribution network into simpler sub‐systems; and the calculation of all the voltages and currents of the medium voltage (MV) network and of the earthing systems using a multiport approach.FindingsThe methodology has been applied to various situations giving precious information on the behaviour of the earthing systems interconnected by means of BBC in presence of conductive effect. The results of the simulation allow to quantify the reduction of the dangerous voltages appearing during an earth fault, in presence of interconnection between the secondary substations' earthing systems, realized by means of BBC.Research limitations/implicationsSome factors can influence the precision of the methodology. Indeed, for a correct simulation of the system it is necessary to know several electrical and geometrical parameters, among all the resistivity of the soil that, often, is known with a large degree of uncertainty.Practical implicationsUtilities are quite interested in this topic. The study of interconnected earthing systems in MV networks with the purpose of identifying safe extended areas named global earthing systems (GES) has important management and economic consequences.Originality/valueThe paper presents an original lumped parameters model of the BBC, able to simulate these elements with a high accuracy, also in presence of the conductive effect, and that can be easily included in the more general model of a distribution line, in order to perform the analytical study of the GES in MV networks. The model proposed allows one to overcome the limits of the application to the MV networks of similar models present in the literature for the study of the same topic in the high‐voltage networks.
A new sensorless hysteresis direct torque control algorithm for PMSM with minimum torque ripples
Authors: Ahmed Adam Ali , Gulez Kayhan 
Published: February 2009

PurposeThe purpose of this paper is to describe a new method for sensorless hysteresis direct torque control (HDTC) algorithm for permanent magnet synchronous motor to minimize torque ripple and electromagnetic interference (EMI) noises.Design/methodology/approachThe design methodology is based on space vector modulation of electrical machines with digital vector control. MATLAB simulations supported with experimental study under C++ are used.FindingsThe simulation and experimental results of this proposed algorithm show adequate dynamic torque performance and considerable torque ripples reduction as well as lower current ripples, lower EMI noise level as compared to traditional HDTC.Research limitations/implicationsThis research is limited to PMSM, however the research can be extended to include induction motor as well. In addition, the actual mathematical relation between the torque ripple and flux ripple can be studied to set the flux and torque bands width in reasonable value, and this relationship can be used to select switching time of the active selected vectors.Practical implicationsThe implementation of the proposed algorithm in microcontroller embedded systems is described. It requires no PI controller in the torque control loop In addition, based on existence direct torque control equipment, it is only required to change the software switching algorithm, to provide smooth torque, given that the switching frequency of the inverter module is more than or equal to 15 kHz and the system is supplied with timers.Originality/valueThe algorithm used in this work utilizes the output of two hysteresis controllers used in the traditional HDTC to determine two adjacent switching vectors per one sample time. The algorithm also uses the magnitude of the torque error, magnitude of the flux error and stator flux position to select the switching time for the selected vectors to control the applied average voltage level in such a way that the torque ripple is minimized. The selection of the switching time of the selected active vectors utilizes novel table structure which reduces the complexity of calculation. This work is directed to designers of ac motor drive system who seek smooth torque performance as well as low EMI noise level.
Fault detection based on continuous wavelet transform and sensor fusion in electric motors
Authors: Ayaz Emine , Öztürk Ahmet , Şeker Serhat , Upadhyaya Belle R. 
Published: February 2009

PurposeThe purpose of this paper is to extract features from vibration signals measured from induction motors subjected to accelerated aging of bearings by fluting tests.Design/methodology/approachAging tests were performed according to IEEE test procedures. The data acquisition involved the measurement of vibration signals using accelerometers that were installed on the bearings and on the motor casing. In this application, only two accelerometers, which were placed near the process end of the motor bearing, are used for data analysis and feature extraction studies. After the data collection, information from the two sensors was combined using simple sensor fusion method under the linearity conditions, and then spectral analysis and time‐scale analysis were performed. The fused vibration signal is decomposed into several scales using continuous wavelet transform (CWT) and its first scale is used to indicate the bearing degradation.FindingsBearing damage characterization was determined between 2‐4 kHz and some specific frequencies were calculated as harmonics of the bearing characteristic frequencies.Research limitations/implicationsThe bearing damage characteristics used in this study is occurred by the experimental study. In terms of the methodology, the use of the CWT shows the fault characteristics from the initial case.Practical implicationsThe experimental study and data acquisition are based on the accelerated aging of the motor bearings. Hence, the real aging is represented by the accelerated one. But, this situation reflects same properties of the aging occurred in industrial environments. The methodology is also applicable to the hardware application.Originality/valueThere are two important aspects of this research: the experimental study and the application of CWT to get the potential defects, which will appear as a failure in future, from the healthy case of the motor bearings.
Influence of foundation on pillar grounding system's characteristics
Authors: Cvetkovic Nenad N. , Rancic Predrag D. 
Published: February 2009

PurposeThe purpose of this paper is to estimate influence of the pillar concrete foundation approximated by a semiconducting semi‐sphere on the pillar grounding system.Design/methodology/approachUnknown current distributions and impedance of pillar grounding system, which consists of a ferro armature modelled as a single electrode inside concrete foundation, ring electrode and two earthing conductors, are determined in this paper. Concrete foundation is approximated by a semi‐spherical semiconducting inhomogeneity. The expressions for electric scalar potential are formed using the quasi‐stationary image theory, including a recently proposed Green's function for the point source in the presence of a semiconducting sphere. Based on the quasi‐stationary antenna model, unknown currents are determined solving the system of integral equations using the moment method and polynomial approximation for current distributions.FindingsThe influence of inhomogeneity is not negligible for real values of specific conductivity of the inhomogeneity domain. The same goes for earthing conductor influence, especially the one on electric scalar potential distribution on the ground surface.Practical implicationsBesides the analyzed system, the model is applicable for solving for example a grounding system in the vicinity of large holes in the ground (pond and small lake) filled with water, treated as semi‐sphere or near vertical container (silage and reservoir) having semi‐spherical basis with a lower one buried in the ground.Originality/valueObtained results give possibility to analyze influence of semiconducting ground inhomogenities, which can be treated as semi‐spherically shaped ones, on grounding system. It results in better accordance of projected and real grounding system's characteristics.
Student‐as‐aspirant: strategic implications for business education
Authors: Salem Khalifa Azaddin 
Published: February 2009

PurposeThe purpose of this paper is twofold. First, to propose a new metaphor, student‐as‐aspirant, which captures well the educational role of students, professors, and business schools. Second, to develop the strategic implications of this metaphor for the management of business schools.Design/methodology/approachA thorough review of relevant literature is conducted and the underlying assumptions of previously suggested metaphors are exposed and challenged. The new metaphor has subsequently been developed based on a broader typology of business offerings.FindingsThe paper shows that the extant metaphors are inappropriate for they misrepresent the nature of learning as the core of business schools' offerings to their students. It concludes with the advantages of the student‐as‐aspirant metaphor.Research limitations/implicationsLimitations are centred on the difficulties faced by students, professors, and business schools in adopting the metaphor.Practical implicationsThe metaphor has strategic implications ranging from stakeholders' expectations, to governance, structure, and strategy of business schools.Originality/valueThe paper is the first to use a typology of four distinct business offerings to propose a new metaphor that sensibly flows from the nature of the transformative learning as the core offering of business schools.
A counter‐intuitive view of the deductive research process
Authors: Svensson Göran 
Published: February 2009

PurposeThe objective of this paper is to describe a counter‐intuitive view of the deductive research process.Design/methodology/approachThe paper should be seen as addressing a debatable subject where there is no “right” or “wrong”, but one which hopefully will stimulate and/or provoke a certain degree of afterthought and reflection. An applied approach to the research process is presented and discussed.FindingsThe paper contends that the counter‐intuitive approach illustrated may uncover pitfalls and flaws in research endeavours at an early stage of an intended research process.Research limitations/implicationsIt is important that the four elements of idea, support, implications, and contribution are thought through properly in detail before too much investment in time and resources, as well as intellectual effort, has been made, in order to avoid frustration and discontent among involved stakeholders.Practical implicationsThe paper contends that it is essential to dedicate and pay attention to the intended research process as a whole before actually going through with it.Originality/valueIt is hoped that the presented counter‐intuitive view of the deductive research process will assist scholars (e.g. junior faculty and doctoral students) in their efforts to perform research endeavours.
Determinants of customer‐oriented behavior in a health care context
Authors: Lanjananda Panisa , Patterson Paul G. 
Published: February 2009

PurposeNurses in hospital settings are a primary contact point and the way their behaviors are perceived by patients is a critical determinant of overall patient satisfaction. The purpose of this paper is to empirically test and extend knowledge of the determinants of customer‐oriented behavior (COB) of contact personnel in a high‐contact service setting (healthcare industry). The paper contributes to the literature by examining two groups of constructs – dispositional variables (e.g. personality traits of the service provider) as well employee perceptions of service climate, mediated by surface traits and organizational commitment, on the dependent variable, COB of nurses in a hospital context.Design/methodology/approachThe study involved both qualitative (focus groups) and a large‐scale survey, with a final sample of 270 nurses from five hospitals in Thailand. The dependent variable was a self‐reported measure of COB. Tests for common method bias suggested however that this was not a problem. All measures were sourced from the literature and demonstrated sound measurement properties. The conceptual model was tested using structural equation modeling.FindingsAnalysis supported the hypothesized model. Basic personality (extraversion, emotional stability, conscientiousness, and agreeableness) as well as customer orientation as surface trait (COS) all impact either directly or indirectly, on nurses' COB. Nurses' perceptions of the service climate and their commitment to the hospital are also significant predictors.Research limitations/implicationsFuture research might attempt to obtain objective measures of nurses' performance in lieu of self‐report measures. Further, as the healthcare industry has very specific characteristics (high affect, high anxiety among patients, high customization, etc.) this model should be tested in a variety of service settings. For healthcare managers, the findings, especially related to basic personality traits, have important implications for the type of person that should be recruited. The adage “Hire for attitude, but train for skill” certainly applies here.Originality/valueThe paper's contribution lies in analyzing the impact that both basic personality (extraversion, emotional stability, conscientiousness, and agreeableness) as well as surface traits, have on nurses' behavior; and simultaneously examining the impact of nurses' perceptions of service climate and organizational commitment.
Loyalty, perceived value and relationship quality in healthcare services
Authors: Moliner Miguel A. 
Published: February 2009

PurposeThe purpose of this paper is to justify the central role played by post‐purchase perceived value and relationship quality in the explanation of loyalty behaviour/intentions.Design/methodology/approachThe paper starts from a conceptual framework based on agency theory. From this theoretical base the concepts of post‐purchase perceived value and relationship quality are derived. The causal model is tested on a sample of hospital users.FindingsThe results show that perceived functional value exercises a significant influence over consumer satisfaction and trust. The main antecedents of loyalty are trust and satisfaction.Research limitations/implicationsThe analysis has focussed on two hospitals, so the sample, though sufficient, is restricted to two specific cases.Practical implicationsThe recommendation is that firms should introduce into their strategies the concept of perceived value, overcoming a vision excessively focussed on quality.Originality/valueThe paper has adapted a previous model to identify the antecedents of loyalty. The antecedents that have been identified up to now are highly speculative.
The emergence of technology‐based service systems
Authors: Essén Anna 
Published: February 2009

PurposeThe purpose of this paper is to propose a framework for studying the process of technology‐based service system innovation from a broad perspective using an approach that elucidates the non‐linear facets of this process. The framework draws on Lévy‐Strauss's concept of bricolage, which implies that individuals' “making do with resources at hand,” as opposed to managerial visions, can trigger innovation. This concept is combined with the notion of technological drift and with a model of emergentism.Design/methodology/approachThe paper uses case study data from the Swedish elderly homecare setting.FindingsThe findings illustrate how the emergence of technology‐based care services can be triggered by an injection of energy in terms of a new technological resource being made available in an organization, proceeding as a continuous interaction between personnel repurposing and recombining resources at hand, positive and negative feedback dynamics, institutional regulations and culture‐related stabilizing mechanisms.Research limitations/implicationsNew services can arise as a result of a number of efforts and events that, in isolation, might appear insignificant. Taken together, and interacting with enabling and constraining forces that promote the emergence of certain new services and prevent others, such acts and events generate unpredictable outcomes. The result may be incremental but by no means trivial innovations.Originality/valueThe paper suggests an approach to innovation that complements conventional thinking in the new service development literature. The proposed framework can help to explain how and why certain new services emerge and why others do not in unexpected and unpredictable ways.
Taking a feminist approach to information systems research and using the “thinking tools” provided by the sociologist Pierre Bourdieu
Authors: Richardson Helen 
Published: February 2009

PurposeThis paper aims to contribute a personal account of doing critical research that uses the social theory of Pierre Bourdieu and also that takes a feminist approach to research. It aims to reflect on what this might mean in order to understand information systems and their uses at work and in everyday life.Design/methodology/approachThe approach is confessional and describes the way in which critical qualitative research was undertaken in specific areas – that of call centres in Northwest England, gender and the UK ICT labour market and PhD research into issues of gender and home e‐shopping.FindingsThe findings as such suggest that social theory and critical approaches to research can contribute to understanding of IS at work and in everyday life. The account discusses the complexity of applying social theories and how difficult theoretical tomes are to understand, especially for the novice researcher.Practical implicationsThe paper highlights the importance of hearing the silent or silenced voices and letting stories be told. A theme throughout is how theory is linked to practice.Originality/valueThe paper contributes to the special issue call for reflexive essays written in simple terms with details about how and why particular social theories or approaches were adopted. This will be of value to PhD and IS researchers whose work is informed by social theory.
A social actor understanding of the institutional structures at play in information systems development
Authors: Rowlands Bruce 
Published: February 2009

PurposeThis paper seeks to provide insights into the process of applying Lamb & Kling's user as social actor model as an institutional lens to analyse data and to generate findings of IS practice.Design/methodology/approachThe paper provides an example from a recently published research project why the social actor model was chosen, and an application of how the model was operationalised in data collection and analysis.FindingsThe paper provides two illustrations of theorising the social actor model at different levels: at an elementary level by using instantiation to map the model's constructs to a match in the transcript text; and at a higher level where the model enabled the paper to tie together a number of individual phenomena to construct a broader higher‐level schema.Originality/valueAs the social actor model is relatively new, and few guidelines or examples exist, the paper provides rich insights into the difficulties with the application of this model and a solution for coping with these so that other researchers can read of an example that may be similar to their own and therefore guide their work.