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Article
Publication date: 1 January 1968

L.M. Cowburn and B.J. Enright

The City University Library has now extended its automation programme to include the subject index to the classified catalogue, the authority files and the press‐cuttings subject…

Abstract

The City University Library has now extended its automation programme to include the subject index to the classified catalogue, the authority files and the press‐cuttings subject index.

Details

Program, vol. 1 no. 8
Type: Research Article
ISSN: 0033-0337

Article
Publication date: 1 June 2004

Olivier Chadebec, Jean‐Louis Coulomb, Gilles Cauffet, Jean‐Paul Bongiraud and Sébastien Guérin

This paper deals with the problem of magnetization identification. We consider a ferromagnetic body placed in an inductor field. The goal of this work is, from static magnetic…

Abstract

This paper deals with the problem of magnetization identification. We consider a ferromagnetic body placed in an inductor field. The goal of this work is, from static magnetic field measurements taken around the device, to obtain an accurate model of its magnetization. This inverse problem is usually ill‐posed and its solution is non‐unique. It is then necessary to use mathematical regularization. However, we prefer to transform it to a better posed one by incorporating our physical knowledge of the problem. Our approach is tested on the magnetization's identification of a real ferromagnetic sheet.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 23 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 4 January 2008

G. Cauffet, J.L. Coulomb, S. Guerin, O. Chadebec and Y. Vuillermet

This paper aims to present the use of magnetic gradient, and magnetic potential measurements in the specific case of magnetization identification for a thin sheet. Usually…

Abstract

Purpose

This paper aims to present the use of magnetic gradient, and magnetic potential measurements in the specific case of magnetization identification for a thin sheet. Usually, induction measurements are only used.

Design/methodology/approach

After a brief description of the magnetic gradient and magnetic scalar potential notions, methods to calculate them are presented and validated. These two kinds of measurements are tested for a numerical identification case. Then, virtual measurements can be generated and used for inverse problem resolution. Advantages of using induction, magnetic gradient or magnetic potential measurements are then discussed.

Findings

A previous method to solve inverse problem based on induction measurement has been increased by the capability of using other kind of measurements. A numerical approach has allowed to validate the use of magnetic gradient or magnetic scalar potential measurement as information sources.

Originality/value

Usually, induction measurements are only used. Inversion resolution using other kind of measurements than the induction can be made. An experimental validation has been done for gradient measurements.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 March 2004

Richard Ulrich

All capacitor dielectric materials, whether used for discrete or embedded applications, can be grouped into two general categories: paraelectric and ferroelectric. Ferroelectrics…

Abstract

All capacitor dielectric materials, whether used for discrete or embedded applications, can be grouped into two general categories: paraelectric and ferroelectric. Ferroelectrics generally exhibit much higher dielectric constants, but are also less stable with regard to temperature, frequency, voltage, time and film thickness. There are dozens of each of these materials that have been used in discrete capacitors and about ten that are either available for use in embedded capacitors or will soon be marketed for that purpose. The commercialized materials can be broken down into four sub‐categories: thick‐film polymers, ferroelectric powder in polymer binders, thin‐film paraelectrics, and thick‐film ferroelectrics. These four classifications are evaluated with regard to their electrical performance, ease of fabrication, and suitability for specific applications.

Details

Circuit World, vol. 30 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 June 2004

Hans Vande Sande, François Henrotte, Kay Hameyer and Ludo Froyen

For anisotropic materials, the magnetic field vector H→ and the flux density vector B→ are parallel with each other only along a few distinct directions. When performing…

Abstract

For anisotropic materials, the magnetic field vector H→ and the flux density vector B→ are parallel with each other only along a few distinct directions. When performing unidirectional measurements, only the component of B→ along the direction under consideration is measured. It is not possible to deduce the angle between B→ and H→ from unidirectional measurements alone. For ferromagnetic materials having a Goss‐texture, as most transformer steels have, this paper demonstrates a way to compute this angle a posteriori, by the combination of measurements with a physical anisotropy model.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 23 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 12 November 2020

Rafal Mech

Investigations over new types of materials as a potential power source for different types of devices were raised dramatically in the last few years. It is connected especially…

1259

Abstract

Purpose

Investigations over new types of materials as a potential power source for different types of devices were raised dramatically in the last few years. It is connected especially with global needs and that most of the devices in our world need electricity to work. In this paper, an investigation on magnetoelectric effect in the magnetostrictive-piezoelectric composite material is presented.

Design/methodology/approach

An author's research setup for investigation of magnetoelectric effect in the developed novel material was prepared. The new composite material was made of magnetostrictive particles of Terfenol-D and lead zirconium titanate (PZT) material.

Findings

Obtained results show that changes in an electric voltage output from the prepared material are highly dependent on the changes in external magnetic field. It was found out that rate of changes of magnetic field around composite material is one of the most important factors which has influence on the magnetoelectric effect. Taking into account the obtained results, it was proven that prepared hybrid material shows magnetoelectric effect in the case of work in alternating magnetic field.

Originality/value

This phenomenon might be used in a field of energy harvesting as potential power source for devices with low power consumption. Moreover, this new material gives an opportunity to be used as an additional gauge for determination of deformation or crack propagation in the samples during fatigue tests.

Details

International Journal of Structural Integrity, vol. 12 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 1 June 2001

Pierre Ueberschlag

PVDF piezo polymers are new, valuable materials for sensing and actuating applications. These materials are strong candidates for new sensors that cannot be realised with…

13041

Abstract

PVDF piezo polymers are new, valuable materials for sensing and actuating applications. These materials are strong candidates for new sensors that cannot be realised with piezoceramics or single crystals. The combination of the mechanical properties of a plastic material with those of a piezoelectric material led to new sensors and transducers whose design is not easy. For this reason, the characteristics and properties of piezo polymer are described as well as basic knowledge that engineers need for technical use.

Details

Sensor Review, vol. 21 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 19 December 2017

Mohammad Malikan

The purpose of this paper is to predict the mechanical behavior of a piezoelectric nanoplate under shear stability by taking electric voltage into account in thermal environment.

Abstract

Purpose

The purpose of this paper is to predict the mechanical behavior of a piezoelectric nanoplate under shear stability by taking electric voltage into account in thermal environment.

Design/methodology/approach

Simplified first-order shear deformation theory has been used as a displacement field. Modified couple stress theory has been applied for considering small-size effects. An analytical solution has been taken into account for various boundary conditions.

Findings

The length scale impact on the results of any boundary conditions increases with an increase in l parameter. The effect of external electric voltage on the critical shear load is more than room temperature effects. With increasing aspect ratio the critical shear load decreases and external electric voltage becomes more impressive. By considering piezoelectric nanoplates, it is proved that the temperature rise cannot become a sensitive factor on the buckling behavior. The length scale parameter has more effect for more flexible boundary conditions than others. By considering nanosize, the consideration has led to much bigger critical load vs macro plate.

Originality/value

In the current paper for the first time the simplified first-order shear deformation theory is used for obtaining governing equations by using nonlinear strains for shear buckling of a piezoelectric nanoplate. The couple stress theory for the first time is applied on the nonlinear first-order shear deformation theory. For the first time, the thermal environment effects are considered on shear stability of a piezoelectric nanoplate.

Details

Multidiscipline Modeling in Materials and Structures, vol. 14 no. 1
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 16 January 2017

Xuan Song, Zeyu Chen, Liwen Lei, Kirk Shung, Qifa Zhou and Yong Chen

Conventional machining methods for fabricating piezoelectric components such as ultrasound transducer arrays are time-consuming and limited to relatively simple geometries. The…

1130

Abstract

Purpose

Conventional machining methods for fabricating piezoelectric components such as ultrasound transducer arrays are time-consuming and limited to relatively simple geometries. The purpose of this paper is to develop an additive manufacturing process based on the projection-based stereolithography process for the fabrication of functional piezoelectric devices including ultrasound transducers.

Design/methodology/approach

To overcome the challenges in fabricating viscous and low-photosensitive piezocomposite slurry, the authors developed a projection-based stereolithography process by integrating slurry tape-casting and a sliding motion design. Both green-part fabrication and post-processing processes were studied. A prototype system based on the new manufacturing process was developed for the fabrication of green-parts with complex shapes and small features. The challenges in the sintering process to achieve desired functionality were also discussed.

Findings

The presented additive manufacturing process can achieve relatively dense piezoelectric components (approximately 95 per cent). The related property testing results, including X-ray diffraction, scanning electron microscope, dielectric and ferroelectric properties as well as pulse-echo testing, show that the fabricated piezo-components have good potentials to be used in ultrasound transducers and other sensors/actuators.

Originality/value

A novel bottom-up projection system integrated with tape casting is presented to address the challenges in the piezo-composite fabrication, including small curing depth and viscous ceramic slurry recoating. Compared with other additive manufacturing processes, this method can achieve a thin recoating layer (as small as 10 μm) of piezo-composite slurry and can fabricate green parts using slurries with significantly higher solid loadings. After post processing, the fabricated piezoelectric components become dense and functional.

Details

Rapid Prototyping Journal, vol. 23 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 July 1980

D.I. Raitt

An index language usually incorporates various methods for improving recall and/or precision when searching. Recall devices tend to increase the size of retrieved document sets…

Abstract

An index language usually incorporates various methods for improving recall and/or precision when searching. Recall devices tend to increase the size of retrieved document sets, while precision devices tend to reduce them. The most common recall and precision devices are described in general terms and their usage in several thesauri is examined. The thesauri looked at relate to databases available for searching in the ESA IRS online information system at one time or another and include the NASA Thesaurus; Thesaurus of Engineering and Scientific Terms; Thesaurus of Metallurgical Terms; Subject Headings used by the USAEC; Subject Headings for Engineering; INIS Thesaurus and the INSPEC Thesaurus. The extent to and the way in which the recall and precision devices are used in the ESA IRS online system for controlled and uncontrolled subject term searching are discussed.

Details

Aslib Proceedings, vol. 32 no. 7
Type: Research Article
ISSN: 0001-253X

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