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The implementation of novel coaxial dipole antennas has been shown to be a satisfactory diagnostic platform for the prediction of orthopaedic bone fracture healing outcomes. These techniques require mechanical deflection of implanted metallic hardware (i.e., rods and plates), which, when loaded, produce measurable changes in the resonant frequency of the adjacent antenna. Despite promising initial results, the coiled coaxial antenna design is limited by large antenna sizes and nonlinearity in the resonant frequency data. The purpose of this study was to develop two Vivaldi antennas (a.k.a., “standard” and “miniaturized”) to address these challenges. Antenna behaviors were first computationally modeled prior to prototype fabrication. In subsequent benchtop tests, metallic plate segments were displaced from the prototype antennas via precision linear actuator while measuring resultant change in resonant frequency. Close agreement was observed between computational and benchtop results, where antennas were highly sensitive to small displacements of the metallic hardware, with sensitivity decreasing nonlinearly with increasing distance. Greater sensitivity was observed for the miniaturized design for both stainless steel and titanium implants. Additionally, these data demonstrated that by taking resonant frequency data during implant displacement and then again during antenna displacement from the same sample, via linear actuators, that “antenna calibration procedures” could be used to enable a clinically relevant quantification of fracture stiffness from the raw resonant frequency data. These improvements mitigate diagnostic challenges associated with nonlinear resonant frequency response seen in previous antenna designs.

Motor variability is a prominent feature of the human movement that, nowadays, can be easily measured through different sensors and analyzed using different types of variables, and it seems to be related to functional and adaptative motor behavior. It has been stated that motor variability is related to the system’s flexibility needed to choose the right degrees of freedom (DoFs) to adapt to constant environmental changes. However, the potential relationship between motor variability and DoFs is unknown. The aim of this study was to analyze how motor variability, both the amount and structure, changes depending on the mechanical DoFs involved in the movement control. For this purpose, movement variability was assessed by a tracking sensor in five tasks with different DoFs, and the amount, using standard deviation, and the structure of variability, through fuzzy entropy and detrended fluctuation analysis, were also assessed. The results showed a higher amount of variability and a less predictable and more auto-correlated variability structure in the long-term when more mechanical DoFs are implied. The studies that analyze motor variability should consider the type of movement and the DoFs involved in the analyzed task since, as the findings have shown, both factors have a noticeable influence on the amount and the structure of motor variability.

Wear is one of the common faults in the mechanical transmission system. Detection of wear particles in lubricating oil can detect and evaluate the wear degree of mechanical equipment. The electromagnetic sensor for metal wear particle detection can be connected in series with the oil circuit, which has the advantages of full liquid flow, simple structure, distinguishing metal properties, and not being influenced by bubbles and vibration. In view of the shortcomings of the existing electromagnetic sensor for wear particle detection, the detection principle and the induction electromotive force model were studied, and the magnetic field change of the metal particles through three coil differential solenoids was analysed. The optimisation design method was proposed here, which was about the related parameters, such as the wire diameter, the coil turns, the coil widths and so on. The experimental analysis of the sensor was carried out based on detection hardware system that could provide the phase-locked amplification function. The 10-mm inner diameter sensor could detect the minimum 100-μm ferromagnetic metal abrasive particles after optimisation. The developed sensor could provide data information for the abrasive particle detection, fault diagnosis and early warning of wear degree of mechanical equipment.

The anterior drawer test (ADT) is the gold standard examination for the diagnosis of anterior talofibular ligamentinsufficiency,although there is noquantitative evaluation of ADT that is generally usable and reliable.An electromagnetic sensor (EMS)has been used to quantitatively evaluate joint kinematics, and has a high potential to be applied to the ankle joint. The aim of this study was to validatethe EMS measurement of the ADTin comparison to the fluoroscopic evaluationand to evaluate the reproducibility of the EMS measurement.Six feet were included,and an examinerperformed the ADT5 times for each foot while the anterior translation of the ankle jointwas quantitative evaluatedusing EMS and fluoroscope simultaneously. The anterior translation of the ankle joint during the ADT in EMS and in fluoroscope was 8.1 ± 5.7 mm and 3.6 ± 2.4 mm.Astrong correlation was observed between the measurements using EMS and fluoroscope (p < 0.01, the correlation coefficient = 0.91). Another 20 feet were included, and three examiners performed the ADT five times for each foot with the EMS measurement. The intra and inter-examiner reliability was 0.99 and 0.89.The EMS could quantify the anterior translation during the ADT which corresponds to fluoroscopic evaluation.

A promising approach for monitoring and predicting the course of bone fracture healing is by measuring the mechanical load-sharing between the healing callus and the implanted fixation hardware. Previous technologies have used implantable sensors which require modification to the fixation hardware and may carry long term biocompatibility risks. The objective of this paper was to optimize and evaluate a method of externally sensing hardware load-sharing based on the electromagnetic near field effects of a radio-frequency antenna. A series of parametric experiments was conducted to optimize the dimensional parameters of a coaxial dipole antenna to improve the antenna’s sensitivity to displacement of a metal plate. The results of the parametric tests guided the design of an optimized antenna, including a coiled loop antenna structure. The antenna was then evaluated for its efficacy in sensing the displacement of a metal plate as well as the deflection of an orthopaedic fracture fixation plate due to an applied load via physical experiments and computational simulations. The antenna’s resonant frequency was sensitive to the displacement of a metal plate, and followed an inverse-square relationship with plate distance. The antenna was also able to sense the bending deflection of the mechanically loaded fracture plate, with the resonant frequency following an approximately linear relationship with applied load. Computational finite-element electromagnetic predictions closely matched the experimental data. This method of sensing plate deflections may be effective for measuring the mechanical load sharing in fractured bones in order to monitor and predict the course of fracture healing.

In this paper, an inverse method was developed which can, in principle, reconstruct arbitrary permeability, conductivity, thickness, and lift-off with a multi-frequency electromagnetic sensor from inductance spectroscopic measurements. Both the finite element method and the Dodd & Deeds formulation are used to solve the forward problem during the inversion process. For the inverse solution, a modified Newton-Raphson method was used to adjust each set of parameters (permeability, conductivity, thickness, and lift-off) to fit inductances (measured or simulated) in a least-squared sense because of its known convergence properties. The approximate Jacobian matrix (sensitivity matrix) for each set of the parameter is obtained by the perturbation method. Results from an industrial-scale multi-frequency sensor are presented including the effects of noise. The results are verified with measurements and simulations of selected cases. The findings are significant because they show for the first time that the inductance spectra can be inverted in practice to determine the key values (permeability, conductivity, thickness, and lift-off) with a relative error of less than 5% during the thermal processing of metallic plates.

This paper presents the MSM structure magnetic detector device that normally detects the electromagnetic wave. The device is special design for magnetic field detector and still detects the electromagnetic wave as normal function. The schottky diode with the split contacts structure allows us to reach this target. The device operates with the saturation current and the magnetic response is the current difference between two contacts which is injected from one metal and deflected in semiconductor toward to another metal. From the simulation result by Sentaurus TCAD, the relative sensitivity is 14.19 mT -1 at the current 0.3 μA. This device is the first MSM multi-sensor for magnetic and electromagnetic wave detector.

The velocity of various objects measured within a large number of disciplines and activities. This paper presents the process of designing an accurate method and equipment for the measurement of velocity in one-shot nonlinear processes, which occur only once and are thus characterized by zero repeatability. The measurement methods must therefore enable the recording, saving, and retroactive evaluation of the processes at a pre-defined accuracy; all these operations are performed to facilitate comparison of the recorded event and other similar processes. However, the electromagnetic method described in the paper does not include the disadvantages of known optical methods. We therefore present the design of an inductive sensor equipped with an electronic signal processing system. This design is based on numerical evaluation of the relativistic effect occurring during the application of the electromagnetic principle in sensing the position and velocity of an object J. Van Bladel. The final section of the paper contains a discussion of the measured results. The authors investigate the use of a coupled model of the magnetic field and analyze the motion of a conductive object in this field. The analysis shows that, for an exact evaluation of the influence of all effects, it is necessary to consider the phenomena related to the movement of a system relative to the other one. It is shown that related distinctive effects affect the resultant electromagnetic field distribution already at the relative velocity of v0= 1ms-1. Publikace ppopisuje využití numerického modelu pro měření vysoce pochybujících se objektů

WOS: 000432411800040, In high-voltage systems partial discharges (PD) may occur due to the degradation of insulation materials in addition to different scenarios such as material properties, construction, setup and operation conditions. Especially for a power transformer, the degradation of inner insulation may prevent regular operation and hence cause failure. In a long time period even low-level PD activity may cause degradation on the insulator. If the deterioration caused by the PD is detected in an early phase, potential damage may be prevented. Due to the complex and close structure of power transformers and other high-voltage systems, it is not easy to estimate the exact location of a PD. This study proposes a novel approach to detect and analyze an artificial PD in a laboratory room setup, which is especially designed for simulation of possible PD source in a large scale structure such as power transformer. Electromagnetic (EM) PD sensors are commonly used to detect electromagnetic pulses emitted from PD sources. In this work, the time differences of arrivals (TDOA) which are obtained from PD signals are subjected to multilateration technique to estimate the exact location. A novel energy level method is introduced to overcome correct TDOA extraction problem. Cramer-Rao bound (CRB) is used for calculation of the minimum achievable estimation error of proposed method. In order to display the accuracy of location estimation, CRB and the mean square error graphics of the estimated location parameters are given for the comparison.

Analysis of the electromagnetic (EM) properties of power station steels, measured using a non-contact magnetic sensor, is of significance as such properties are indicative of the microstructure of the material and can be potentially exploited for non-destructive testing. In this paper, we present EM measurements of cylindrical power station steel samples (P9 and T22 grades) with different microstructures: normalised and tempered (representative of the initial condition), as normalised and after service exposure. In order to obtain the magnetic properties the B-H curves of these samples were measured. Cylindrical air-cored and printed circuit board (PCB) coil integrated sensors were used to measure the incremental permeability. Analytical and numerical methods (Finite Elements Methods) were employed to calculate the sensor response of these samples. The electromagnetic properties of the different steels were inferred by fitting the finite element models to the measured results. In addition, sensitivity and error analysis were carried out to evaluate the accuracy of the method. ?? 2013 Elsevier B.V. cited By (since 1996)1

In this paper, we present the results of non-invasive blood glycaemia measurements. The blood used in the measurements was calf blood. The measurement method uses an electromagnetic sensor based on eddy currents, which allows the detection of blood glycaemia levels through the variation of the dielectric parameters of the blood. A change in blood glucose concentration causes a variation in the dielectric parameters, in particular conductivity. Detection is only possible at a resonant frequency. The measurements were taken in a static and dynamic state (with and without circulation of blood). The blood is inside a plastic tube placed within the sensor and is surrounded by gelatine, which simulates muscular tissue. The plastic tube simulates the vein where blood circulation occurs. The in vitro results in both cases (static and dynamic) are provided. Under unfavourable conditions we can detect a change of +/- 2 g/l of glucose. We present and discuss these results.

20 Pag., 3 Tabl., 6 Fig. The definitive version is available at: http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1475-2743/, Diagnosis of soil salinity and its spatial variability is required to establish control measures in irrigated agriculture. This article shows the usefulness of electromagnetic (EM) and soil sampling techniques to map salinity. We analysed the salinity of a 1-ha plot of surface-irrigated olive plantation in Aragon, NE Spain, by measuring the electrical conductivity of the saturation extract (ECe) of soil samples taken at 22 points, and by reading the Geonics EM38 sensor at 141 points in the horizontal (EMH) and vertical (EMV) dipole positions. EMH and EMV values had asymmetrical bimodal distributions, with most readings in the non-saline range and a sharp transition to relatively high readings. Most salinity profiles were uniform (i.e. EMH=EMV), except in areas with high salinity and concurrent shallow water tables, where the profiles were inverted as shown by EMH > EMV, and by ECe being greater in shallow than in deeper layers. The regressions of ECe on EM readings predicted ECe with R2 > 84% for the 0–100 to 0–150 cm soil depths. We then produced salinity contour maps from the 141 ECe values estimated from the electromagnetic readings and the 22 measured values of ECe. Owing to the high soil sampling density, the maps were similar (i.e. mean surface-weighted ECe values between 3.9 dS m−1 and 4.2 dS m−1), although the electromagnetically estimated ECe improved the mapping of details. Whereas soil sampling is preferred for analysing the vertical distribution of soil salinity, the electromagnetic sensor is ideal for mapping the lateral variability of soil salinity., This article is a result of the project RTA01-001, funded by INIA (Ministry of Science and Technology of Spain). The second author was granted by Fundación Cándido Iturriaga - María Dañobeitia.

Deckblatt, Inhaltsverzeichnis, Danksagung und Erklärung Einleitung Was ist Navigation? Grundlagen Klinische Anwendungen Diskussion Schlussfolgerungen Abkürzungen Literatur Anhang, Navigationssysteme haben sich als hilfreiches Instrument in der kraniellen Neurochirurgie etabliert. So genannte sensor-basierte Navigationsverfahren nutzen zur Positionsbestimmung : a) einen Signalgeber, welcher ein fest definiertes elektromagnetisches Feld im Bereich des Operationssitus induziert und b) kleine Sensorenspulen, welche die Position verschiedener Operationsinstrumente im elektromagnetischen Feld detektieren. Aufgrund fehlender klinischer Daten und Langzeitergebnisse wurden elektromagnetische Systeme jedoch lange als störanfällig und ungenau angesehen. Mit der Entwicklung einer gepulsten DC Technik können nun jedoch auch Genauigkeiten erreicht werden, die mit den bereits etablierten optischen und mechanischen Messverfahren vergleichbar sind. Zu beachten ist jedoch, dass auch bei diesen Systemen die Beeinflussung der Messgenauigkeit innerhalb des Arbeitsbereiches mit dem Ferritanteil und der Magnetisierbarkeit der unterschiedlichen Metalle (Titan < Aluminium < hochlegierte Metalle < niedriglegierte Metalle) steigt. Die Arbeitsweise, die zu erzielenden Genauigkeiten, äußere Einflüsse und technische Limits eines solchen Systems wurden anhand von 128 Fällen untersucht., Navigation systems have established themselves as helpful instruments in cranial neurosurgery. For the specification of position, so-called sensor- based navigation techniques use: a) a signal emitter that induces a fixed, defined electromagnetic field in the area of the operation site and b) small sensors that detect the position of various operating instruments in the electromagnetic field. Because of the lack of clinical data and long-term studies, electromagnetic systems have been viewed for a long time as prone to malfunctioning, temperamental and imprecise. With the development of a pulsed DC technique, precision levels can also now be reached that are comparable with those of the already established optical and mechanical measuring procedures. However, It must be noted that the influence on the measuring accuracy within the operating field increases with increasing iron component and magnetizability of the various metals used in the operating theatre (titanium < aluminium < high alloy metals < low allow metals). The technique of DC pulsed electromagnetic navigation, accuracies, external influences on the system and technical limits were investigated in 128 cases.

[ES] Las técnicas electromagnéticas (EM) permiten cartografiar la salinidad edáfica con sensor portátil. Pero las lecturas del sensor deben traducirse, por calibración, a una medida estándar como la conductividad eléctrica del extracto saturado (CEe). Algunos autores usan transformaciones no lineales para mejorar las calibraciones. En este trabajo se utilizan muestras de suelo hasta 1 m de profundidad tomadas en tres años consecutivos en una parcela de regadio, mostrando que los métodos lineales son suficientemente precisos para cartografiar la salinidad del suelo. Además, parecen ofrecer información sobre el perfil de salinidad, si bien este aspecto deberá estudiarse más detenidamente. Las caractéristicas técnicas del sensor EM empleado producen una relación no lineal entre la conductividad eléctrica del suelo y la lectura del sensor, que puede corregirse en base a los datos técnicos facilitados por el fabricante., [FR] Les techniques électromagnétiques (EM) permettent de cartographier la salinité des sols avec un senseur portatif. Mais les lectures du senseur doivent être traduites, par calibration, en une mesure standard comme la conductibilité électrique de l’extrait saturé (CEe). Certains auteurs utilisent des transformations non linéaires pour améliorer les calibrations. Dans le présent travail, on a utilisé des échantillons de sol jusqu’à 1 m de profondeur prélevés trois années succes-sives dans une parcelle irriguée, ce qui a permis de montrer que les méthodes linéaires sont suffisamment précises pour cartographier la salinité du sol. De plus, elles semblent offrir de l’information sur le profil de salinité, encore que cet aspect doivent être encore étudié de manière plus approfondie. Les caractéristiques techniques du senseur EM utilisé produisent une relation non linéaire entre la conductivité électrique du sol et la lecture du senseur, qui peut être corrigée sur la base des données techniques fournies par le fabricant., {EN] Soil salinity surveys easy with a hand-held electromagnetic sensor (EM), but the readings have to be converted into a standard measure of soil salinity, such as the electrical conductivity of the soil saturated extract (CEe). Several authors use nonlinear transformations of EM readings to avoid collinearity between regression variables or to decrease the errors of the estimates. EM data and I-m-depth soil samples taken on an irrigated plot in three consecutive years, showed that linear methods of calibration are sufficiently accurate for soil salinity surveys. Linear methods also seem to give information about the salinity profile, although this aspect should be tested further. Non linearities between EM readings and bulksoil electrical conductivity may appear due to the design characteristics of the EM sensor employed, but they can be corrected for using the technical characteristics provided by the manufacturer., Este trabajo fue financiado por INIA (Ministerio deAgricultura, Pesca y Alimentación).

The paper proposes simple electromagnetic sensor based on shorted stacked patches and provides study of its performance in comparison with commercially available standard sensor. The calibration curve was obtained across the whole operating (GSM 900) bandwidth and measurement comparison of the reference and test sensor with real GSM signals was provided. The sensitivity of the proposed sensor to various relative positions in space was also analyzed. The possibility of simultaneous measurement of field components was discussed.