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Article
Publication date: 1 July 2006

B. Tellini, R. Giannetti and S. Lizón Martínez

This paper aims to show a low‐cost and easy to use measurement method for characterizing magnetic material B(H) relation up to medium frequencies providing an acceptable overall…

223

Abstract

Purpose

This paper aims to show a low‐cost and easy to use measurement method for characterizing magnetic material B(H) relation up to medium frequencies providing an acceptable overall accuracy of the acquired data.

Design/methodology/approach

Saturation fields at MHz frequencies are obtained through resonance effects of properly designed circuit. Simulations and measurements are presented and discussed.

Findings

The paper shows the flexibility of the method and the possibility to use it for a complete characterization of the magnetic cores. Discussions and possible extension to rotating field measurements are reported.

Originality/value

The paper provides information on a low‐cost and easy to use measurement method to characterize magnetic hysteretic materials.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 25 no. 3
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 7 April 2022

Hongwei Yang, Yingying Wang, Meng Zhang and Lianchun Long

This paper aims to provide a symplectic conservation numerical analysis method for the study of nonlinear LC circuit.

44

Abstract

Purpose

This paper aims to provide a symplectic conservation numerical analysis method for the study of nonlinear LC circuit.

Design/methodology/approach

The flux linkage control type nonlinear inductance model is adopted, and the LC circuit can be converted into the Hamiltonian system by introducing the electric charge as the state variable of the flux linkage. The nonlinear Hamiltonian matrix equation can be solved by perturbation method, which can be written as the sum of linear and nonlinear terms. Firstly, the linear part can be solved exactly. On this basis, the nonlinear part is analyzed by the canonical transformation. Then, the coefficient matrix of the obtained equation is still a Hamiltonian matrix, so symplectic conservation is achieved.

Findings

Numerical results reveal that the method proposed has strong stability, high precision and efficiency, and it has great advantages in long-term simulations.

Originality/value

This method provides a novel and effective way in studying the nonlinear LC circuit.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 41 no. 5
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 10 May 2019

Yahia Achour and Jacek Starzyński

This paper aims to describe a new concept of transformer based on the displacement current. The paper shows how this idea can be translated into reality and presents an example of…

141

Abstract

Purpose

This paper aims to describe a new concept of transformer based on the displacement current. The paper shows how this idea can be translated into reality and presents an example of a working design.

Design/methodology/approach

The authors replace the primary winding of the transformer with a capacitor. The displacement current between the capacitor plates induces a magnetic flux in the core. This flux in turn induces electromotive force in the classical secondary winding.

Findings

The basic mathematical aspects illustrated by results obtained from a simulation developed using a commercial software ANSYS-HFSS are given. The saturation of the magnetic core due to the applied high-frequency range is investigated and simulated using a finite difference time domain code implemented in MATLAB. A prototype transformer was built and tested; the obtained results confirm the previous ones from simulations.

Originality/value

A new concept of the single winding transformer was used as a pulse forming circuit.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 38 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 16 March 2015

Yingping Hong, Ting Liang, Pinggang Jia, Wenyi Liu, Qiulin Tan, Chen Li, Tingli Zheng, Binger Ge and Jijun Xiong

Physical contact and traditional sensitive structure Physical contact and traditional pressure-sensitive structures typically do not operate well in harsh environments. This paper…

474

Abstract

Purpose

Physical contact and traditional sensitive structure Physical contact and traditional pressure-sensitive structures typically do not operate well in harsh environments. This paper proposes a high-temperature pressure measurement system for wireless passive pressure sensors on the basis of inductively coupled LC resonant circuits.

Design/methodology/approach

This paper begins with a general introduction to the high-temperature pressure measurement system, which consists of a reader antenna inductively coupled to the sensor circuit, a readout unit and a heat insulation unit. The design and fabrication of the proposed measurement system are then described in detail.

Findings

A wireless passive pressure sensor without an air channel is fabricated using high-temperature co-fired ceramics (HTCC) technology and its signal is measured by the designed measurement system. The designed heat insulation unit keeps the reader antenna in a safe environment of 159.5°C when the passive sensor is located in a 900°C high-temperature zone continuously for 0.5 h. The proposed system can effectively detect the sensor’s resonance frequency variation in a high bandwidth from 1 to 100 MHz with a frequency resolution of 0.006 MHz, tested from room temperature to 500°C for 30 min.

Originality/value

Expensive and bulky equipment (impedance analyzers or network analyzers) restrict the use of the readout method outside the laboratory environment. This paper shows that a novel readout circuit can replace the laboratory equipment to demodulate the measured pressure by extracting the various sensors’ resonant frequency. The proposed measurement system realizes automatic and continuous pressure monitoring in a high-temperature environment with a coupled distance of 2.5 cm. The research finding is meaningful for the measurement of passive pressure sensors under a wide temperature range.

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Article
Publication date: 2 January 2018

Dong Yang, Zhenxiang Liu, Ting Shu, Lijia Yang, Jianming Ouyang and Shen Zhi

Helical coil electromagnetic launchers (HEMLs) using motion-induced commutation strategy solve the problem of synchronization control perfectly. HEMLs can meet the requirements of…

136

Abstract

Purpose

Helical coil electromagnetic launchers (HEMLs) using motion-induced commutation strategy solve the problem of synchronization control perfectly. HEMLs can meet the requirements of multiple applications such as the electromagnetic catapult, electromagnetic mortar and high-velocity coilgun. The trade-off between the velocity and efficiency is an important basis for these different applications. To optimize such objectives before actual design, the purpose of this paper is to focus on the efficient and flexible calculation model and algorithm. A novel structure of HEML is proposed after the transient simulation by this algorithm, which can improve the energy conversion efficiency and suppress the muzzle arc without affecting the velocity too much.

Design/methodology/approach

The equivalent circuit model of the launcher is established and the governing equations are derived. A combination of the four-stage Runge–Kutta method and the trapezoidal quadrature formula are used to solve the governing equations.

Findings

With smaller number of turns in the coils of HEML, the velocity is larger and the efficiency is lower. The non-uniform HEML is an effective option to improve the energy conversion efficiency and to suppress the muzzle arc with almost the same muzzle velocity as the conventional HEML.

Originality/value

The paper presents a common model and a flexible fast numerical method which can be used in multi-objective optimization of HEMLs such as the genetic algorithm. A new structure of the non-uniform HEML is proposed to improve the energy conversion efficiency and to suppress the muzzle arc of the launcher.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 37 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 17 May 2023

Onur Yasar, Selcuk Ekici, Enver Yalcin and Tahir Hikmet Karakoç

Lithium-polymer batteries have common usage in aviation industry especially unmanned aerial vehicles (UAV). Overheating is a serious problem in lithium-polymer batteries. Various…

252

Abstract

Purpose

Lithium-polymer batteries have common usage in aviation industry especially unmanned aerial vehicles (UAV). Overheating is a serious problem in lithium-polymer batteries. Various cooling methods are performed to keep lithium-polymer batteries in the desired temperature range. The purpose of this paper is to examine pouch type lithium-polymer battery with plate fins by using particle image velocimetry (PIV) and computational fluid dynamics (CFD) for UAV.

Design/methodology/approach

Battery models were produced with a 3D printer. The upper surfaces of fabricated battery models were covered with plate fins with different fin heights and fin thicknesses. Velocities were obtained with PIV and CFD. Temperature dissipations were acquired with numerical simulations.

Findings

At the end of the study, the second battery model gave the lowest temperature values among the battery models. Temperature values of the seventh battery model were the highest temperatures. Fin cooling reduced the maximum cell temperatures noticeably. Numerical simulations agreed with PIV measurements well.

Practical implications

This paper takes into account two essential tools such as PIV and CFD, for fluid mechanics, which are significant in the aviation industry and engineering life.

Originality/value

The originality of this paper depends on investigation of both PIV and CFD for UAV and developing a cooling method that can be feasible for landing and take-off phases for UAV.

Details

Aircraft Engineering and Aerospace Technology, vol. 95 no. 7
Type: Research Article
ISSN: 1748-8842

Keywords

Available. Open Access. Open Access
Article
Publication date: 8 August 2022

Veronica Ines Fernandez Orellano and Taís Cardoso Tellini

This study investigates the impact of political alignment on intergovernmental transfers to the Brazilian unified health system (SUS). The authors analyzed both automatic…

622

Abstract

Purpose

This study investigates the impact of political alignment on intergovernmental transfers to the Brazilian unified health system (SUS). The authors analyzed both automatic transfers based on pre-established rules and discretionary transfers, using two criteria of political alignment between mayors and the central government.

Design/methodology/approach

For the empirical analysis the authors used regression-discontinuity design (RDD) and the outcomes of close elections between 2001 and 2017.

Findings

The results indicate positive and statistically significant effects of party alignment on the two transfer categories, especially discretionary transfers, but also on transfers based on pre-established rules. The effect of direct party alignment, when mayors and the president are from the same party, is greater than that resulting from coalitions established in municipal and federal elections.

Research limitations/implications

The positive effect of party alignment was found both in discretionary transfers (those that do not have previously established rules) and some non-discretionary transfers (although they have previously defined regulations). A part of these regulations depends on production capacity and on taking part in programs promoted by the central government, which may produce entropy in the financing system, and a margin to benefit political allies. In the case of the SUS system, it is possible that this entropy is greater in the basic health care category than in the moderate and high complexity one, allowing a higher margin for discretion in transfers allocated to the former. Stricter rules associated to basic health care transfers would be desirable.

Practical implications

In Brazil, stricter rules and monitoring associated to basic healthcare intergovernmental transfers would be desirable.

Social implications

The results may inspire some improvement in the mechanisms that govern the distribution of resources to basic healthcare in Brazil, improving social welfare by improving social justice in the distribution of resources to basic healthcare.

Originality/value

The authors does not know any other study about the impact of party alignment on the distribution of intergovernmental transfers to the Brazilian unified health system.

Details

EconomiA, vol. 23 no. 1
Type: Research Article
ISSN: 1517-7580

Keywords

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Article
Publication date: 17 August 2015

Davide Aloini, Luisa Pellegrini, Valentina Lazzarotti and Raffaella Manzini

The purpose of this study is to shed further light on determinants of the openness degree to give a more conclusive evidence to the research in the field. In particular, the…

1756

Abstract

Purpose

The purpose of this study is to shed further light on determinants of the openness degree to give a more conclusive evidence to the research in the field. In particular, the influence exerted by the technological strategy is still debated, in that evidence on the relationship between the technological strategy and openness is conflicting.

Design/methodology/approach

The authors put forward a structural equation model which enriches the state-of-the-art literature by explicitly testing the interplay among technological strategy, openness (innovatively measured in terms of partner intensity, phase intensity and variety in terms of partners, phases and contents) and innovation performance. Our study relies on data from 415 firms based on a research survey developed in Finland, Italy and Sweden.

Findings

Findings show that openness, if measured in terms of partner intensity and phase intensity, fully mediates the relationship between technological strategy and innovation performance, by suggesting that the effectiveness of a firm’s technologically aggressive behavior is strongly related to the intensification of collaboration with the partners along the innovation funnel. Conversely, openness variety seems to play an opposite role and is influenced differently by partner and phase intensity. This result likely emphasizes how the cost-side of open behavior becomes harder to manage, and thus costly, when it involves too many different types of partners, phases and contents.

Practical implications

Firms that adopt a technologically aggressive strategy are recommended to deeply open their innovation process to foster innovation performance. However, because of the fact that a high level of openness variety could generate some drawbacks, managers should be very careful in the management of different phases, sources and content. Therefore, what clearly emerges is a call to find adequate strategies for effectively managing the collaboration process to avoid the waste of resources and initiatives.

Originality/value

Originality and the value of the paper reside in a more fine-grained definition of the openness concept, which takes into consideration other facets of openness compared to those usually analyzed in the literature, and a powerful statistical model, such as structural equation modeling, offering great advantages and flexibility in matching the theoretical model with the data.

Details

Measuring Business Excellence, vol. 19 no. 3
Type: Research Article
ISSN: 1368-3047

Keywords

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Article
Publication date: 1 June 2000

P.Di Barba

Introduces the fourth and final chapter of the ISEF 1999 Proceedings by stating electric and magnetic fields are influenced, in a reciprocal way, by thermal and mechanical fields…

480

Abstract

Introduces the fourth and final chapter of the ISEF 1999 Proceedings by stating electric and magnetic fields are influenced, in a reciprocal way, by thermal and mechanical fields. Looks at the coupling of fields in a device or a system as a prescribed effect. Points out that there are 12 contributions included ‐ covering magnetic levitation or induction heating, superconducting devices and possible effects to the human body due to electric impressed fields.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 19 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 1 June 2000

A. Savini

Gives introductory remarks about chapter 1 of this group of 31 papers, from ISEF 1999 Proceedings, in the methodologies for field analysis, in the electromagnetic community…

1158

Abstract

Gives introductory remarks about chapter 1 of this group of 31 papers, from ISEF 1999 Proceedings, in the methodologies for field analysis, in the electromagnetic community. Observes that computer package implementation theory contributes to clarification. Discusses the areas covered by some of the papers ‐ such as artificial intelligence using fuzzy logic. Includes applications such as permanent magnets and looks at eddy current problems. States the finite element method is currently the most popular method used for field computation. Closes by pointing out the amalgam of topics.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 19 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

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