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The Magnetic Flux Leakage (MFL) testing method is a well-established branch of electromagnetic non-destructive testing technology extensively used to observe, analyze and estimate the level of imperfections (cracks, corrosions, pits, dents, etc.) affecting the quality of ferromagnetic steel structures. However the conventional MFL (DCMFL) method are not capable of estimating the defect sizes and orientation, hence an additional transducer is required to provide the extra information needed. This paper takes the detection and quantification of tangentially oriented rectangular surface and far-surface hairline cracks as the research objective. It uses an optimized pulsed magnetic flux leakage probe system to establish the location and geometries of such cracks. The results gathered from the approach show that data using the axial (B x ) field component can provide detailed locational information about hairline cracks especially the shape, size and orientation when positioned perpendicular to the applied field.

A novel inductive curvature sensor has been fabricated for the purpose of monitoring angular joint movements of the finger. The sensor is a planar figure-of-eight coil sandwiched between a flexible polyester film and a Metglas magnetostrictive ribbon. The coil and its flexible substrate measures 7.5 mm wide, 50 mm long, and 110 μm thick, with the Metglas ribbon and bonding layer contributing an additional 50 μm, approximately. Inductance changes were measured as a function of sensor bending induced through uniaxial displacements. Bending the sensor exerts stresses on the magnetostrictive ribbon and, due to the Villari effect, leads to changes in permeability and therefore inductance. Inductance changes up to 350 nH, a 20 % decrease of the initial inductance value, were recorded. The main advantages of this sensor are ease of use, small size profile, flexibility, and simplicity. The results indicate great potential for measuring the angular articulation of human joints.

A new versatile scanning hardware based on a Micromagnetics® STJ-020 MgO-based tunnelling magnetoresistance (TMR) sensor has been developed to volumetrically scan the thin boundary layer above a given sample. An (x, y) planar scan of the surface of a 7.5 mm × 7.5 mm sample of grain-oriented (3% Si) electrical steel is presented. Stray fields normal to the surface between −116 and 272 A/m are measured. At 10 q, m/pixel domain and micro-domain structures are seen. At 5 q, m/pixel the micro-domain structures resolve into clear Lancet domains. The domain images presented have greater qualitative similarity with Kerr effect observations than with Bitter technique results. An (x, z) vertical scan along a 2.35 mm transect reveals the perpendicular extent of the stray fields, with the normal components shown to emanate from the domain bodies and extend approximately 40–100 q, m from the sample surface. With the aim of investigating how the stray fields close back onto the surface, the (x, z) transect is repeated with the sensor at 5, 10, 15 and 20 degrees from the vertical. For the first time, the stray fields from surface domains viewed by other techniques in only a planar (x, y) projection have been studied in the (x, z) plane perpendicular to the surface.

The ability to orientate and navigate is critically important for the survival of all migratory birds and other animals. Progress in understanding the mechanisms underlying these capabilities and, in particular, the importance of a sensitivity to the Earth’s magnetic field has, thus far, been constrained by the limited number of techniques available for the analysis of often complex behavioural responses. Methods used to track the movements of animals, such as birds, have varied depending on the degree of accuracy required. Most conventional approaches involve the use of a camera for recording and then measuring an animal's head movements in response to a variety of external stimuli, such as changes in magnetic fields. However, video tracking analysis (VTA) will generally only provide a 2D tracking of head angle. Moreover, such a video analysis can only provide information about movements when the head is in view of the camera. In order to overcome these limitations, the novel invention reported here utilises a lightweight (

Recognizing and tracking articulations of the human hand is key to the development of areas such as robotics, virtual reality systems and physical rehabilitation. Based on the principle of crossed-polarization detection, a novel optical sensor with a hinge configuration, is proposed to monitor finger articulation. Using 3D printing technology, we fabricated a lightweight and compact sensor suited to attaching on fingers. The weighted average method was applied to the sensor's output data to determine angular positions corresponding to finger joint articulations. The experimental results show excellent consistency with theoretical predictions. The sensor features good accuracy (±0.5% of full scale) and repeatability, improved sensitivity, and an improved measuring range of 180°. The performance of the sensor is a promising development for monitoring finger articulation. Future work will focus on integrating multiple sensors as part of an instrumented glove to evaluate the true potential for monitoring hand articulation.

This paper presents our proposed design for a multi-core planar fluxgate sensor for low magnetic field measurements. It stands out from other fluxgate designs by using three core layers. This will increase flux concentration in the pickup coil and thus improve field sensitivity. The basic structure of the multi core fluxgate magnetic sensor is shown in Fig. 1. It consists of three-core flux concentrators, an excitation coil and a sensing coil. The actual implementation of the structure in PCB technology is shown in Fig. 1. The 20 turn planar excitation coil was constructed with a thickness of 30μm and sandwiched between the three-cores. The magnetic components were measured from the sensing coil, 400μm wide with 20 turns. The excitation and sensing coils were on separate PCB layers separated by a distance of 50 μm from each other.

The purpose of this research is to evaluate two types of sensor that can be applied to monitor human finger flexion in real time. Currently, flex sensors are the most commonly used resistance sensors in glove-based systems. However, measurements show that current flex sensors have problems associated with hysteresis error, low sensitivity at small angles, and considerable time drift with large bending angles which render them unsuitable for tracking hand motion at low speed. In contrast, the developed optical sensor prototype has good repeatability, sensitivity and low temporal drift, as well as offering the capability of accurate measurements in both clockwise and anticlockwise directions. The sensor is based on the principle of crossed-polarization detection, and consists of one LED, two rotatable polarizers and one photodiode amplifier which enables the detection of changes in polarized light intensity proportional to angular rotation.

The remarkable ability of diverse animals to orientate and navigate during migration and homing over long distances has fascinated scientists for years. However, how the birds sense and process the magnetic field information in their brains is not known [1]. Recent advances have brought new insights into how field direction, intensity, and polarity are neurally encoded by single cells [2]. Several bird species are believed to possess physiological mechanisms that enable them to navigate using the magnetic field. Generally, it is accepted that there are two sensory magnetoreception mechanisms: a light-dependent cytochrome-based magnetic compass and a magnetite-based map [3]. To date, reproducing experimental results has been problematic perhaps related to the difficulty in controlling magnetic field conditions [4]. We describe here a special instrumentation setup of three-dimensional Helmholtz coils, which are used to cancel out the Earth's magnetic field and then generate a field within the range of the Earth's magnetic field, controlled by a specific current source. The magnetic mapping within the volume of the constructed system is measured and compared against magnetic modeling. The visual programming language, LabVIEW (version 2012SP1) of National Instruments (NI)[5], is used to control the system to generate any specific magnetic field condition.

Behavioural experiments often require continuous monitoring of the responses that animals make in different situations and in response to various stimuli. Formerly, recording visual observations of animals followed by the manual post hoc analysis of the data was the most commonly employed approach and has the advantage of being non-invasive. However, manual data extraction can be very time-consuming and introduces a risk of bias in identifying salient responses. Although techniques have been developed for specific applications to automate the analysis of behaviours, including some commercial solutions, many are not always adequate for the particular situation or sufficiently flexible to measure the desired movement. We have developed and implemented a relatively low cost system for video recording and reliably extracting data characterizing animal's kinetic responses. This instrumentation has been successfully utilized in our investigations of pigeon head movements by enabling us to record and compare behavioural responses to different types of stimuli.

A novel electromagnetic transducer speaker, that aims to employ whole body vibration of the panel to reduce the poor bass and impulse response associated with present flat panel speaker, have been tested and analyzed for the audible frequency range. Frequency response of a moving magnet configuration of this device shows consistent and linear output for various excitation current levels over the whole audible frequency range. Phase and magnitude measurement shows existence of resonance at the very low end i.e. below 1 kHz of the audio spectrum. Finite element modelling has been used to examine single transducer operation and the magnetic interaction between neighboring transducers in a matrix array format. Experimental results show the correct positioning of the transducers in a matrix configuration, as observed by the simulation, reduces the effects of interferences on the magnetic transducers. Also, results show that larger matrix array transducer speaker exhibit better low frequency response.

Due to the coupled effects between axial magnetic force and unbalanced magnetic force on the proposal geometry construction in spindle motor, the tracking status will be seriously affected during the data storage processing in media system. There are some types of axial geometric configurations are analyzed and discussed the unbalanced magnetic forces for high precious and high positioning spindle motor by 3D finite element method, which are including of permanent magnet rotor and slotted stator with coils in this paper, the variation of axial geometric configurations are investigated by experimental design parameter to calculate the electromagnetic forces, and to measure the vibrating magnitudes, to evaluate the coupling dynamic characteristics in spindle motor

In this paper the rotational power losses under controlled high magnetic field intensity (up to 20 kA/m) are presented for the first time. Three types of electrical steel sheets are used namely; fully processed non-oriented 0.50 mm thick, low Si content (FPNO), conventional grain-oriented 0.27 mm thick, 3 % Si (CGO) and high-permeability grain-oriented 0.27 mm thick, 3 % Si (HPGO).

A novel hybrid force sensor system has been produced and successfully shown to be able to measure dynamic kN-level forces. It uses an innovative frequency modulation (FM) based system using an amorphous wire sensor wound around a magnetically biased Terfenol-D rod to detect dynamic, stress-induced changes in magnetisation. The hybrid sensor is able to successfully detect low-frequency sinusoidal forces up to 2kN. It is considered that the sensor system will be able to detect compressive cyclic stresses, applied forced waveforms and forces.

A new thin amorphous panel miniaturization actuator will be expected to improve or develop at low fundamental frequency with high quality acoustic output in this paper, modeled using the magnetic energy by the 3D FEM (finite element method). The computation model analysis will be evaluated and implemented by experiments. As the unique concerns is miniaturization for the loudspeaker on commercial products, micro-actuator will provide a potential solution to meet the requirement of miniaturization for the loudspeaker with Flat panel speaker technology, which operates under bending wave principle, and exploits the resonance of the panel instead of the traditional piston motion to produce sound.

A fully automated localized power loss measurement system with a repeatability of +or-1% was designed and constructed. A thermistor and associated electronics were used to measure the localized power loss from the initial rate of rise of temperature in magnetic materials. The designed system was calibrated by using I/sup 2/R Joule loss obtained from a known DC current through a copper strip sample. The system was capable of detecting the localized power loss not only on conventional silicon-iron laminations but also on a single amorphous ribbon magnetized in the flux density range of 1 T to B/sub s/ in a frequency range of 50 Hz to 5 kHz. The quality of the system was assessed by comparing the results to data obtained from other conventional systems. A change in temperature on the order of 0.0002 degrees C can be detected by the system. >