bluuebunny/crossref_metadata_2025_split huggingface dataset:
Permanent magnet machine design trade-offs to achieve sensorless control at high load
Authors: Caner Murat , Gerada Chris , Asher Greg 
Published: January 2015

Purpose
– The purpose of this paper is to introduce a new design optimization technique for a surface mounted permanent magnet (SMPM) machine to increase sensorless performance at high loadings by compromising with torque capability.

Design/methodology/approach
– An SMPM parametric machine model was created and analysed by finite element analysis (FEA) software by means of the Matlab environment. Eight geometric parameters of the machine were optimized using genetic algorithms (GAs). The outer volume of the machine, namely copper loss per volume, was kept constant. In order to prevent sensorless performance loss at high loading, an optimization process was realized using two loading stages: maximum torque with minimum ripple at nominal load and maximum self-sensing capability at twice load. In order to show the effectiveness of the proposed technique, the obtained results were compared with the classical one-stage optimization realized for each loading condition separately.

Findings
– With the proposed technique, fairly good performance results of the optimization were obtained when compared with the one-stage optimizations. Using the proposed technique, sensorless performance of the motor was highly increased by compromising torque capability for high loading. Additionally, this paper shows that the self-sensing properties of a SMPM machine should be considered at the design stage of the machine.

Originality/value
– In related literature, design optimization studies for the sensorless capability of SMPM motor are very few. By increasing optimization performance, new proposed technique provides to achieve good result at high load for sensorless performance compromising torque capability.
Machine design and control strategy for wide-speed-range PMSG systems
Authors: Shen Jianxin , Miao Dong-Min 
Published: January 2015

Purpose
– The purpose of this paper is to focus on the machine design and control strategy of the permanent magnet synchronous generator (PMSG) system, especially utilized in variable speed applications, in order to stabilize the output voltage on the dc link over a wide speed range.

Design/methodology/approach
– Different ac/dc power converter topologies are comparatively studied, each with an accordingly designed PMSG, so as to investigate the influence of the armature winding inductance as well as the relationship between the PMSG and power converter topologies.

Findings
– Pulse width modulation (PWM) rectifier is preferable for the said application due to its good performance and controllability. Moreover, by employing the PWM rectifier, relatively large inductance of the PMSG is considered for both short-circuit current reduction and field regulation.

Originality/value
– Field-regulating control is realized with a space vector PWM (SVPWM) rectifier, which can weaken the PMSG magnetic field during high-speed operation, while even properly enhance the field at low speed, ensuring a small change of the PMSG output voltage and a stable dc voltage.
Study of the temperature uniformity of aluminium billets heated by superconducting DC induction heaters
Authors: Wang Yawei , Gao Hao , Li Zhuyong , Ping Yang , Jin Zhijian , Hong Zhiyong 
Published: January 2015

Purpose
– The purpose of this paper is to analyse and improve the temperature uniformity of aluminium billets heated by superconducting DC induction heaters.

Design/methodology/approach
– A 3D electromagnetic model coupled with a heat transfer model is developed to calculate the heating process of the billets which are rotated in uniform transverse DC magnetic field. A laboratory-scale DC induction heater prototype has been built to validate the model. The results from simulation and measurement have a good agreement. The model is used to investigate the factors affecting the temperature uniformity of aluminium billets.

Findings
– The results from simulation show that lower rotation speeds always mean better temperature uniformity along the radial direction, due to the increase in power penetration. However, the situation is very different for the temperature distribution along the axial direction. When the rotation speed is low, the temperature at the ends is lower than other parts. The situation reverses as the rotation speeds increase. This phenomenon is referred to as the “ending effect” in this paper.

Research limitations/implications
– Because of the ending effect, a lower rotation speed does not always result in better overall temperature uniformity, especially for billets of smaller sizes.

Practical implications
– There is an optimal rotation speed that yields the best overall temperature uniformity. Lower rotation speeds are not always preferred. The results and numerical model developed are very useful in the design of a superconducting DC induction heater.

Originality/value
– The temperature uniformity of aluminium billets heated by DC induction heaters is investigated and optimized.
Microcontroller-based inverter topology integrated in PV systems
Authors: Bouzguenda Mounir , Selmi Tarek , Gastli Adel , Masmoudi Ahmed 
Published: January 2015

Purpose
– The purpose of this paper is to study the problem of the leakage currents in transformerless inverter topologies. It proposes a novel topology and how important the adopted control strategy on the power quality produced by the inverter.

Design/methodology/approach
– The paper presents an investigation of a novel transformerless inverter topology. It adopted a control strategy in which the DC source is disconnected from the inverter when the zero vectors of the control are applied. By using such control strategy, the electrical efficiency of the whole system was improved and the leakage current was significantly reduced.

Findings
– The paper provides a solution to minimize the leakage current in transformerless inverter topologies. Besides, the problem of zero-crossing distortions was totally eliminated.

Research limitations/implications
– Because of the high conversion ratio of the boost converter, the efficiency of the whole system needs to be enhanced.

Practical implications
– The paper includes the experimental results of the proposed topology which are in good match with the simulation results.

Originality/value
– This paper identifies a need to study the leakage current phenomena in transformerless inverter topologies.
Investigation of magnet segmentation techniques for eddy current losses reduction in permanent magnets electrical machines
Authors: Zoubida Belli , Mekideche Mohamed Rachid 
Published: January 2015

Purpose
– Reducing eddy current losses in magnets of electrical machines can be obtained by means of several techniques. The magnet segmentation is the most popular one. It imposes the least restrictions on machine performances. This paper investigates the effectiveness of the magnet circumferential segmentation technique to reduce these undesirable losses. The full and partial magnet segmentation are both studied for a frequency range from few Hz to a dozen of kHz. To increase the efficiency of these techniques to reduce losses for any working frequency, an optimization strategy based on coupling of finite elements analysis and genetic algorithm is applied. The purpose of this paper is to define the parameters of the total and partial segmentation that can ensure the best reduction of eddy current losses.

Design/methodology/approach
– First, a model to analyze eddy current losses is presented. Second, the effectiveness of full and partial magnet circumferential segmentation to reduce eddy loss is studied for a range of frequencies from few Hz to a dozen of kHz. To achieve these purposes a 2-D finite element model is developed under MATLAB environment. In a third step of the work, an optimization process is applied to adjust the segmentation design parameters for best reduction of eddy current losses in case of surface mounted permanent magnets synchronous machine.

Findings
– In case of the skin effect operating, both full and partial magnet segmentations can lead to eddy current losses increases. Such deviations of magnet segmentation techniques can be avoided by an appropriate choice of their design parameters.

Originality/value
– Few works are dedicated to investigate partial magnet segmentation for eddy current losses reduction. This paper studied the effectiveness and behaviour of partial segmentation for different frequency ranges. To avoid eventual anomalies related to the skin effect an optimization process based on the association of the finite elements analysis to genetic algorithm method is adopted.
Unified model of temperature dependence of core losses in soft magnetic materials exposed to non-sinusoidal flux waveforms and DC bias condition
Authors: Ruszczyk Adam , Sokalski Krzysztof 
Published: January 2015

Purpose
– The purpose of this paper is to present modelling of power losses dependences on temperature in soft magnetic materials exposed to non-sinusoidal flux waveforms and DC bias condition.

Design/methodology/approach
– Scaling theory allows the power loss density to be derived in the form of a general homogeneous function, which depends on the peak-to-peak of the magnetic inductance ΔB, frequency f, DC bias HDC and temperature T. The form of this function has been generated through the Maclaurin expansion with respect to scaled frequency, which suit very much for the Bertotti decomposition. The parameters of the model consist of expansion coefficients, scaling exponents, parameters of DC bias mapping, parameters of temperature factor and tuning exponents. Values of these model parameters were estimated on the basis of measured data of total power density losses.

Findings
– The main finding of the paper is a unified methodology for the derivation of a mathematical model which satisfactorily describes the total power density losses versus ΔB, f, HDC, and T in soft magnetic devices.

Research limitations/implications
– Still the derived method does not describe dependences of the power density loss on shape and size of considered sample.

Practical implications
– The most important achievement is of the practical use. The paper is useful for device designers.

Originality/value
– This paper presents the algorithm which enables us to calculate core losses while the temperature is changing. Moreover, this method is effective regardless of soft magnetic material type and the flux waveforms as well as the DC bias condition. The application of scaling theory in the description of energy losses in soft magnetic materials justifies that soft magnetic materials are scaling invariant systems.
Simple nonlinear MEC-based model for sensitivity analysis and genetic optimization of permanent-magnet
Authors: Mohammadi Sajjad , Vahidi Behrooz , Mirsalim Mojtaba , Lesani Hamid 
Published: January 2015

Purpose
– The purpose of this paper is to develop an effective, yet simple analytical framework for optimization of permanent-magnet synchronous machines. Also, single/multi-objective optimizations are performed for a case-study machine with surface-mounted permanent magnets.

Design/methodology/approach
– First, an accurate magnetic equivalent circuit is developed which takes all the material such as iron saturation and PM parameters into account. Then, through a Fourier analysis, it is combined with the d-q model of PM synchronous machines to achieve an optimization framework including the developed torque, back-EMF and a number of design considerations. Finally, a genetic algorithm (GA) is employed in the single/multi-objective design optimizations, which offers several design characteristics upon different desired outcomes.

Findings
– An analytical design framework for the optimization of permanent-magnet synchronous machines is developed in this paper that can effectively account for all material properties such as iron saturation and PM characteristics, and take into account the design considerations, all of which are shown as superiorities of the proposed approach over the existing method. In addition, the proposed framework is relatively simpler in terms of implementing. The model is verified by employing finite element method. Moreover, sensitivity analysis is carried out to investigate the influence of the design parameters on the machine performance, which provides valuable information for the designer of such devices. Finally, a GA is utilized to perform single/multi-objective optimization schemes whose objectives are minimizing the torque ripples, back-EMF total harmonic distortion and PM volume.

Originality/value
– The proposed framework is new approach that could be employed in the design optimization of PM synchronous machines. Contrary to existing method, it is simpler and more effective in taking the material properties such as iron saturation and PM characteristics into account.
Exploring the creative climate in an open innovation arena
Authors: Yström Anna , Aspenberg Hedvig , Kumlin Annika 
Published: January 2015

Purpose– By increasing connectivity between multiple partners, the new paradigm of open innovation has been argued to stimulate creativity. However, there are still few empirical studies exploring what influence this new form of organizing for innovation has on the creative climate. The purpose of this paper is to start filling that knowledge gap by exploring the creative climate in an open innovation arena called SAFER, where 26 partner organizations meet to innovate together.Design/methodology/approach– The paper is based on a mixed method consisting of a quantitative creative climate questionnaire complemented by qualitative data gathering through interviews.Findings– The findings suggest that the networking and cross-functional meetings within the arena are beneficial to facilitate a creative climate, but there are challenges in handling uncertainties such as work identities, information sharing and knowledge transparency.Practical implications– The arena is found to be rather dependent on interaction with the outside environment, implying that a well-constructed arena from an organizational point of view is in itself not enough to ensure a creative climate. The project organization of the arena makes the general perception of SAFER fragmented, and it is questioned whether such an arena could or should strive for only one creative climate.Originality/value– The paper presents an interesting example of how introducing open innovation affects the creative climate, and discusses the difficulty of using established methods for assessing the creative climate in the new, emerging forms of organizing for innovation.
Breather-type kink wave of the (2+1)-dimensional BKP equation
Authors: Chen Wei , Chen Hanlin , Dai Zhengde 
Published: January 2015

Purpose
– The purpose of this paper is to find solutions for the (2+1)-dimensional B-type Kadomtsev-Petviashvili equation and to research the quality of B-type Kadomtsev-Petviashvili equation.

Design/methodology/approach
– The authors apply the extended three-wave approach and the homoclinic test technique to solve the B-type Kadomtsev-Petviashvili equation.

Findings
– The authors obtain breather type of cross-kink solutions, doubly breather type of kink solitary solutions and the breather type of kink wave solutions for B-type Kadomtsev-Petviashvili equation.

Research limitations/implications
– As nonlinear evolution equations are characterized by rich dynamical behaviors, the authors have just found some of them and others are still to be found.

Originality/value
– These results may help us to investigate the local structure and the interaction of waves in high-dimensional models.
Solitons and other solutions of the long-short wave equation
Authors: Ebadi Ghodrat , Mojaver Aida , Kumar Sachin , Biswas Anjan 
Published: January 2015

Purpose– The purpose of this paper is to discuss the integrability studies to the long-short wave equation that is studied in the context of shallow water waves. There are several integration tools that are applied to obtain the soliton and other solutions to the equation. The integration techniques are traveling waves, exp-function method,G′/G-expansion method and several others.Design/methodology/approach– The design of the paper is structured with an introduction to the model. First the traveling wave hypothesis approach leads to the waves of permanent form. This eventually leads to the formulation of other approaches that conforms to the expected results.Findings– The findings are a spectrum of solutions that lead to the clearer understanding of the physical phenomena of long-short waves. There are several constraint conditions that fall out naturally from the solutions. These poses the restrictions for the existence of the soliton solutions.Originality/value– The results are new and are sharp with Lie symmetry analysis and other advanced integration techniques in place. These lead to the connection between these integration approaches.
Rhetoric or reality? A case study into how, if at all, practical work supports learning in the classroom
Authors: Martindill David , Wilson Elaine 
Published: January 2015

Purpose
– The purpose of this paper is to study the use and value of practical work in the secondary school science classroom. Informed by the findings of a large survey of students from a wide variety of schools, a case study of pupils in the middle secondary range sought to investigate the precise role of practical work in the learning of a specific topic over a series of lessons.

Design/methodology/approach
– Qualitative and quantitative assessment of academic progress of two classes of pupils revealed that students who undertook practical tasks made greater gains in knowledge and understanding than those who undertook non-practical alternatives. In order to explore students’ views about the practical tasks and whether they found them to be an affective and effective aid for their learning, data were collected using questionnaires, lesson observations and interviews of focus groups.

Findings
– The data suggest three reasons why practical work supported pupils’ learning. First, practical work supported their visualisation of abstract concepts and provided a stimulus for the recall of key facts later. Second, it provided a distinctive opportunity for pupils to work collaboratively, with associated gains. Finally, hands-on tasks promoted a classroom atmosphere rich in variety, semi-autonomous learning and self-discovery, which pupils found intrinsically motivational.

Originality/value
– This study, which responds to the criticism practical work has received in recent years, sheds some light on the mechanisms through which the strategy supports learning in certain contexts. Moreover it argues that practical work needs to be effectively planned to maximise the learning gains made by pupils.
The prospects of lesson study in the US
Authors: Gero Greg 
Published: January 2015

Purpose
– Lesson study has emerged as an approach to improving the quality of teaching in the USA. The purpose of this paper is to provide an investigation into teachers’ attitudes toward lesson study. Evidence suggests that lesson study may increase teachers’ content knowledge and their ability to anticipate student misconceptions during lessons. Nevertheless, certain issues have surfaced in the literature. Teachers may struggle with the demands of collaboration, critique of their lessons, and observation of their teaching. Moreover, lesson study may conflict with the existing mandate-monitor culture within many school districts. Understanding how teachers perceive lesson study is vital to gauging the effectiveness of the process.

Design/methodology/approach
– In all, 55 teachers at two elementary schools in urban Los Angeles participated in the researcher-designed survey. For the teachers in this study, participation in lesson study was mandatory, and most had participated in a version of lesson study that emphasized following the established curriculum and district-approved strategies. Data were analyzed using correlational analysis.

Findings
– Results yielded significant associations between teachers’ comfort levels with collaboration, lesson observation, lesson critique, and their support for lesson study. Higher degrees of control by the district over the lesson study process were linked to teachers feeling less responsible for student learning.

Practical implications
– The findings from this study have important implications for the prospects of lesson study as a model of teacher development in the USA.

Originality/value
– This paper fulfils a need to investigate factors that impede and promote the effective implementation of lesson study in the USA.
Cooperative research. A critical strategy in university teacher training. A case study of Lesson and Learning Studies
Authors: Soto Gómez Encarna , Serván Núñez Maria J , Pérez Gómez Angel I 
Published: January 2015

Purpose– The purpose of this paper is to present the possibilities offered by Lesson and Learning Studies (LLS) for training and for improving and generating knowledge by reconstructing the practical knowledge of teachers in university training through joint design, observation and reflection. In short, the research aims to show how merging LLS contributes to developing fundamental teaching skills in new, uncertain contexts and to recreating processes of research and analysis of complex situations from critical and creative perspectives by involving university teachers and student teachers in disciplined, informed reflection on their own practice through shared, narrative productions in a dual spiral which promotes the contrasting of experiences and perspectives in an ongoing manner.Design/methodology/approach– A case study of own practice in a university master’s degree, the aim of which is to develop a training improvement process by following the stages of LLS.Findings– The case study shows the need to reverse the theory-practice sequence and to increase the importance of experience, the relevance of tutoring in the role of teachers, and the significance of cooperation and contrast as learning strategies. The evidence presented shows that LLS can be an extremely useful resource and procedure to reconstruct practical knowledge, facilitating internal contrast between the different espoused theories of the members of the group of teachers, and also between their espoused theories and their practical knowledge, in other words their theories-in-use.Originality/value– The paper explores the value of LLS to reconstruct the practical knowledge of university teachers.