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Interaction of an active electronic implant such as a deep brain stimulation (DBS) system and magnetic resonance imaging (MRI) radiofrequency (RF) fields can induce excessive tissue heating, limiting MRI accessibility. Efforts to quantify RF heating mostly rely on electromagnetic (EM) simulations to assess individualized specific absorption rate (SAR), but such simulations require extensive computational resources. Here, we investigate if a predictive model using machine learning (ML) can predict the local SAR in the tissue around tips of implanted leads from the distribution of the tangential component of the MRI incident electric field, E tan. A dataset of 260 unique patient-derived and artificial DBS lead trajectories was constructed, and the 1 g-averaged SAR, 1 g SARmax, at the lead-tip during 1.5 T MRI was determined by EM simulations. E tan values along each lead's trajectory and the simulated SAR values were used to train and test the ML algorithm. The resulting predictions of the ML algorithm indicated that the distribution of E tan could effectively predict 1 g SARmax at the DBS lead-tip ( R = 0.82). Our results indicate that ML has the potential to provide a fast method for predicting MR-induced power absorption in the tissue around tips of implanted leads such as those in active electronic medical devices.

Considering two annular rotating electron beams in a dielectric-lined waveguide, the frequency spectrum of the azimuthal waves and their field profile distribution are investigated. The charged particle acceleration due to the tangential component of the electric field is simulated. The simulation is carried out for important factors, such as the electron energy gain (acceleration gradient) and the deflection angle in two different vacuum regions (the core and clad of the dielectric waveguide). The graphs of the mentioned parameters versus the traveled distance by the electron are presented, and they are compared with each other. It is found that in some cases, the tangential acceleration of the charged particle in the clad of the cylindrical waveguide can be more effective.

The constitutive equation of masonry-like materials has been generalized in order to account for a limit to the tangential component of the stress, that is proportional to the normal component. This result has been achieved by suitably modifying the convex set made up of all the admissible stresses. The constitutive equation obtained in this manner retains all the properties of normal elastic materials. The model developed has been implemented in the FEM computer code MADY, and applied to the study of masonry shear-walls and arches under monotonic in-plane loads. The reliability of the proposed model is checked through comparisons with some experimental results.

In an actual structure, the arrangement of steel bars is complicated, there are many factors affecting the corrosion of steel bars, and these factors affect each other. However, accurately reflecting the corrosion of steel bars in actual engineering through theoretical calculations is difficult. Besides, it is impossible to detect and evaluate steel bars rust completely and accurately. This article is based on spontaneous magnetic leakage detection technology and adopts the method of stage corrosion and scanning along the reinforcing bar. Based on spontaneous magnetic flux leakage detection technology, the linear change rate of the tangential component curve of the magnetic flux leakage signal generated after the corrosion of a steel bar is studied, and a comparison is made between the steel bar coated concrete samples with different steel bar diameters. In this paper, the &ldquo, origin of magnetic flux leakage signal&rdquo, is defined as a reference point, which is convenient for effectively comparing the magnetic signal curves under all operating conditions. Besides, the &ldquo, rust-magnetic fluctuation parameter&rdquo, is proposed to accurately reflect the sudden change of leakage magnetic field caused by disconnection due to the corrosion of a steel bar. A new data processing method is provided for the non-destructive testing of steel corrosion using the spontaneous magnetic flux leakage effect, which can effectively reduce the influence of steel bar diameter on magnetic flux leakage signal and improve the precision of non-destructive testing technology of steel bar corrosion using the metal magnetic memory effect.

We revisit the impact of geometry on the evolution of stochastic differential equations in embedded Riemannian manifolds. We decompose the Ito-Stratonovich drift adjustment into a projection onto the normal space, a ’pinning’ drift that keeps the process on the manifold and a tangential component. By means of some robotics examples we show how a loss of measurement information changes the drift adjustment so that an Ito-Stratonovich equivalence can be lost.

In order to realize contactless levitation and movement of precision components, a new kind of acoustic prototype driven by standing waves utilizing reverse hydrodynamic effects of non-parallel squeeze film was proposed in this paper. Its mechanism of movement and levitation was revealed by the viscous fluid mechanics and dynamic lubrication theory. It is amazing that the reverse hydrodynamic effects made the levitated plate move along the opposite direction of gravitational tangential component, which was proved in the experiments. The bearing and pushing capacity is predicted by numerical calculation of Reynolds equation and a CFX model. A dimensionless parameter 'voltage difference ratio' was proposed to evaluate the deflection angle of a non-parallel squeeze film, which can guide the prototype design.

This study investigates how the stability of the turning process changes when the tangential component of the cutting force is also taken into account as a compressive force acting on the cutting tool. The tool is modelled by a cantilever beam; the mathematical model is based on the Euler-Bernoulli beam theory. The effect of compression appears through the lateral stiffness of the tool. Two cases are separated in connection with the compressive force: constant and varying forces. Since compression reduces the natural frequency of the cutting tool, this also affects the stable region of the turning operation.

Hardware that uses plug-in detectors and allows one to measure coercive force in the range of few to several hundred A/m in industrial products of different shapes is presented. The operating principle is based on a functional relationship between the tangential component of the magnetic field close to the surface of a residually magnetized article and the coercive force of the article material as well as a connection between the gradient of the field of a magnetic pole formed at the article surface after local magnetization and the coercive force.

In this study, we set out to develop a method for estimating the fine and fast shear deformation of a finger pad, that is, the palm side of a fingertip, as it scans the surface of a material. Using a miniature accelerometer, we measured the acceleration at the radial skin, the deformation of which is accompanied by the shear deformation of the finger pad. Using a transfer function, as specified in a separate experiment, between the pad and side of a finger, we estimated the shear deformation of the finger pad in the frequency domain. A comparison between an estimate based on the accelerometer and another based on a precise force sensor for the tangential component of the interaction force between the fingertip and material surfaces showed that the estimation accuracy was sufficient for frequencies in excess of approximately 20–50 Hz and for skin deformation above $$10^{-6}$$ m. Our technique merely requires that an accelerometer be attached to the side of the fingertip, which allows active texture exploration. These estimates or measurements of the finger skin deformation caused by touching materials will help us to comprehend the relationships between material surfaces and the resulting texture sensations.

Particle image velocimetry (PIV) and an extended solution of Stokes’ second problem were used to validate a computational fluid dynamics (CFD) model of flow in an orbiting dish. Velocity vector components throughout one complete orbit differed between CFD and PIV by less than 5%. Computational velocity magnitudes averaged over the interior 20% radius, the region where the analytical solution is most applicable, were 0.3% higher than the analytical values, while the experimental values in the same region were 2.4% higher. Velocity profiles in the center of the dish across normalized heights that most influence wall shear stress varied on average by ∼–0.00046 for the normalized radial component and by ∼0.0038 for the normalized tangential component compared to the analytical solution. These results represent the most comprehensive validation to date for computational models of the orbiting dish system. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4233–4242, 2017

Purpose This paper aims to study the influence of supply voltage variations on the external magnetic field emitted by grid-powered induction machines (IMs). Design/methodology/approach Two models are developed in the paper to analyse, for different supply voltage values, the influence of the variations of the magnetizing voltage for which there is a link with the tangential component of the external flux. The first is an analytical model based on the IM single-phase-equivalent circuit with variable magnetizing reactance to take into account the saturation of the magnetic circuit. The second is a numerical finite element simulation to model the same phenomenon. Results of both models are analysed with experimental measures of the external flux. Findings The study shows that the amplitude of the external field strongly depends on supply voltage values. Research limitations/implications The investigation is mainly focused on the tangential component of the external magnetic field which is of high importance concerning the applicability of non-invasive methods of diagnosis, as electromagnetic torque estimation developed by the authors or internal fault determination. Originality/value The originality of the paper concerns the characterization of the external flux with the supply voltage for IMs. It is shown that the magnetic circuit radiates external flux differently with the load and with the supply voltage.

We have numerically demonstrated micro droplet migrations by photothermal manipulation, in order to investigate the driving force and accompanying flows. We focus on an oil (oleic acid) droplet in water that provides a positive temperature dependence of interfacial tension. The present direct numerical simulation employs the volume-of-fluid method and the continuum-surface-force method with consideration of temperature dependency. The driving velocity and force magnitude, which we measured quantitatively, agree with experimental and theoretical data. We have found that the dominant driving force exerted on the microdroplet is the interface normal force, i.e., the Laplace pressure, on a curved interface rather than the tangential force. The tangential component directly triggers the Marangoni convection; however, the induced flows inside the droplet are opposite between the cases of “an oil droplet in water” and “a water droplet in oil”. This may be caused by the large difference between the viscosities of water and oil.

The possibility of widening the backscattering pattern (monostatic RCS pattern) of the Van Atta array with changing cylinder radius and array parameters has been studied. Assumed that waveguides are single-mode, and coupling between array radiators occurs through waveguides only. Integral equations obtained in explicit form for tangential component of the electric field intensity in the array elements apertures. Analysis of array RCS performed with different number of array elements pairs N, cylinder radius, aperture size, array spacing, and waveguides lengths.

Non-destructive tests of gantry cranes by means of the residual magnetic field (RMF) method were carried out for a duration of 7 years. Distributions of the residual magnetic field tangential and the normal components of their gradients were determined. A database of magnetograms was created. The results show that the gradients of tangential components can be used to identify and localize stress concentration zones in gantry crane beams. Special attention was given to the unsymmetrical distribution of the tangential component gradient on the surface of the crane beam No. 5 (which was the most loaded one). The anomaly was the effect of a slight torsional deflection of the beam as it was loaded. Numerical simulations with the finite element method (FEM) were used to explain this phenomenon. The displacement boundary conditions introduced into the simulations were established experimentally. Validation was carried out using the X-ray diffraction method, which confirmed the location of strain concentration zones (SCZs) identified by means of RMF testing.

To obtain the change tendency of the wheel’s angular velocity and tangential component of contact force with time of the pinion under the step input during spiral bevel gear meshing, the tooth flank equation of spiral bevel gear was constructed based on the Non-Uniform Rational B-splines curve. The three-dimensional model of the pinion and the wheel were built based on the tooth flank equation. The calculation equation and relative parameters set for the contact force of spiral bevel gear meshing were done based on the Hertz contact theory. A mating of spiral bevel gears was taken as an example for dynamics simulation and the simulation results show that the relative error rate of the angular velocity between simulation and theoretical calculation is 0.054%, and that the relative error rate of tangential component of the contact force between simulation and theoretical calculation is 4.82%. These findings provide the theoretical basis for dynamic characteristics optimization of the spiral bevel gears.

The metal magnetic memory (MMM) method is a nondestructive testing method to inspect the early damage of steel structures. A four-point bending fatigue beam was inspected by this method during the whole fatigue life. The self-magnetic-leakage field (SMLF) values were measured during the test of the Q345B steel beam. Frequency of 3 Hz and stress ratio of 0.2 contributed to the fatigue life of 100,180 cycles. Test results indicate that both the normal and tangential component of the SMLF values can identify the stress concentration and the crack zones. The gradient can reflect the degree of damage. Furthermore, in order to study the change law of the SMLF values in the crack zone, an improved magnetic dipole model considering the crack dimensions and shape is proposed. The model predictions are in very good agreement with the corresponding test results. Lastly, three characteristic parameters, i.e. average ΔHp(y) field values, resultant magnetic field value H and magnetic parameter m, were extracted from the test data. These parameters can judge the fatigue stage and the damage degree of the specimen. Therefore, the research lays the experimental and theoretical foundation for using the MMM method to inspect steel structures under fatigue bending loads.

We have investigated the transmission ability of a layered structure the central layer of which is made of a “left-handed” material (its refractive index is negative) and is separated by two air slabs from a “right-handed” dielectric medium that surrounds the structure. We consider tunneling of energy fluxes through the structure and determine conditions for the complete (reflectionless) transmission of the power of the incident wave through it. We show that this effect is resonant and is observed when the tangential component of the wave vector of the incident wave coincides with the longitudinal wave vector of one of waveguiding eigenmodes of the left-handed layer.

In this paper, a new portable magnetic perturbation probe using a Giant Magneto-Resistance (GMR) sensor to detect and characterize surface cracks in ferromagnetic steels is presented. Measurements from one tangential component of the magnetic flux density are obtained during a single scan over a crack, and two parameters are defined from the output voltage of the GMR sensor: the distance between the peaks, DX, and their voltage difference, DV. The correlations between DX and DV and crack features such as depth, width, and orientation angle are determined. Sensitivity analyses are performed based on the studied features. The probe permits the user to obtain the crack׳s orientation angle using only one measured tangential component of the magnetic flux density. A simple procedure to estimate the crack׳s features is proposed based on the presented analysis.

This study presents a method based on the total internal reflection and the phase-shifting interferometry for measuring the Van Hove singularities in strained graphene. A linearly polarized light passes through some quarter- and half-wave plates, a hemi-cylindrical prism, and a Mach-Zehnder interferometer. The Van Hove singularities manifest themselves as some sharp dips or peaks in the spectrum of the final phase difference of the two interference signals. The numerical analysis demonstrates that the number of Van Hove singularities is independent of the modulus of the applied stress, but their position shifts as the strength of the tension increases. Besides, the number and location of singularities strongly depend on the stress direction relative to the zigzag axis in the graphene lattice. Moreover, we show that the location of singularities is independent of the tension direction relative to the tangential component of the electric field of the incident radiation., Comment: 15 pages, 6 figures

Purpose – Punching of the electrical sheets impair the insulation and make random galvanic contacts between the edges of the sheets. The purpose of this paper is to model the random galvanic contacts at the stator edges of 37 kW induction machine and estimate the additional losses due to these contacts. Design/methodology/approach – The presence of the surface current at the edges of sheets causes the discontinuity in the tangential component of the magnetic field. The surface boundary layer model which is based on this concept is implemented to model the galvanic contacts at the edges of the sheets. Finite element analysis based on magnetic vector potential was done and theoretical statistical study of the random conductivity at the stator edge was performed using brute force method. Findings – Finite element analysis validates the interlaminar current when galvanic contacts are present at the edges of electrical sheets. The case studies show that the rotor and stator losses increases with the thickness ...

Variation of the stress-induced magnetic field of the U75V rail steel under tension was investigated in this research. Various magnetic responses were registered by a magnetometer in the elastic and plastic deformation stages, which can be explained by the microstructural changes in magnetic domains. Two types of defective specimens were also tested to correlate the stress concentration with the magnetic field. It is found that the tangential component of the magnetic field Bx is much more sensitive to local stress concentration than the normal component Bz. The tangential component Bx reaches a peak value at the rupture position, and the peak magnitude is proportional to the concentrated stress caused by the defect. This observation is different from the Q235 steel, whose tangential component Bx and the normal component Bz are equally effective. Such discrepancy might be due to that U75V fails in a more brittle pattern than the Q235 steel. The average value of the Bx along the loading axis can determine the overall stress state of the structure, while the peaks in the Bx curve tell the local stress concentration caused by cracks and dislocation.

In this paper, a new kind of calibration method for current measuring instruments based on Ampere’s law (current transformers, current clamps, Rogowsky probes, and so on) is proposed. The method focuses in the uncertainty associated to the geometric variability of the circuits where the current is to be measured and it does not require to perform any mechanical displacements of the instrument. It is based on the fact that the relevant magnetic effect of a circuit over a measuring instrument is the tangential component of the magnetic strength along the Ampere’s law integration path. This effect can be recreated by the sum of the magnetic effects of a set of predefined circuits, each one excited by a specific current (and different for each circuit to recreate). The method also offers a graphical representation of the instrument response variability when off center indefinite straight wires are applied. An experimental setup and finite-element method simulations have been used to check the results.

Stationary structures formed on the surface of a liquid under the action of an electric field have been studied. With the use of the equations of electrohydrodynamics, it has been shown that cones are formed in a dynamic regime when the current of surface ions, which is induced by the tangential component of the electric field, dominates over the conductivity current in the bulk of a cone and the surface current induced by the flow of the liquid. The electric field strength both inside and outside the cone, as well as the velocity field inside the cone, has been determined. It has been shown that the angle of the cone depends on the current flowing on its surface. The characteristic size of the cone has been determined.

Creepage discharges are a main cause of insulation damage in power transformers during repeated tests or during operation. In this paper, a hazardous region in the insulation structure of power transformers (the interface between solid and liquid insulation at the top edge of a high-voltage electrode) is considered, and the impact of a very important factor of the surface discharge initiation and propagation (the tangential component of the electric field) on the strength of the insulation structure is investigated in power transformers. Insulation system reliability against this tangential component is presented as a safety factor. Two methods based on cumulative stress characteristics and breakdown probability are proposed for safety factor calculation and for the recognition of weak insulation regions. These methods provide essential information on insulation system design and optimization for reducing insulation deteriorations. A case study is performed on the insulation structure of a power transformer that failed during a test at the Iran Transfo Corporation. The redesigned transformer has shown no test failures in the past 10 years.

The results of studies of the stray magnetic-field strength over extensive residual magnetization zones are reported. A correlation between the coercive force and tangential component of stray magnetic field of magnetized zones was found, which allows magnetic nondestructive inspection to be performed with both higher efficiency and resolving ability.

This paper presents a model to predict cutting force and motion of the rotating insert in cutting processes with self-propelled rotary tools (SPRT). Metal cutting utilizing rotary tools is effective to suppress tool wear and thus it is considered to be suitable to attain high performance machining of difficult-to-cut materials. It is well known that a circular insert attached to a rotational axis is self-propelled due to inclined chip flow on rake face plane by setting certain oblique angle. A resultant insert rotation speed can be easily predicted considering a frictionless rotary axis. However, friction at the rotary axis of SPRTs may not be negligible in practice especially when slide bearings are employed. In order to investigate the influence of the friction at the rotation axis on the rotary cutting process, a new cutting model is proposed. As the friction at the rotation axis causes a decrease in a speed of round insert rotation, an equivalent oblique cutting process is taken into account in the proposed model utilizing conventional theoretical model. In the equivalent process, the tangential component of the resultant cutting force corresponds to the friction force at the rotary axis. The friction force is determined by cutting force component normal to force-bearing mechanism and the bearing's friction coefficient. Considering the equilibrium condition in cutting and friction forces, the resultant cutting force and the insert rotation speed are iteratively computed in the proposed model. Edge force model is also associated with the oblique cutting model, which is not negligible especially in machining difficult-to-cut materials. The developed model is extended to simulate milling processes with SPRTs. The proposed model is experimentally verified, and influence of the bearing friction of SPRT on the process is clarified.

Based on the mechanical analysis of hydraulic excavator working device, the mechanical relationships between the work load (digging resistance) on the bucket teeth and forces on bucket hydraulic cylinder and boom hydraulic cylinder has been established. Utilizing the geometric relationships among each parts of working device, the formulae of the normal component and the tangential component of excavating resistance have been deduced. A hydraulic excavator load force-time process measurement method was provided, which has such advantages as less measuring points, simpler measuring procedure and lower cost. And the load force-time process could make the load force spectrum for structure optimization design and fatigue life evaluation without the limit of cross section shape change.

The cores of electrical machines are generally punched and laminated to reduce the eddy current losses. These manufacturing processes such as punching and cutting deform the electrical sheets and deteriorate its magnetic properties. Burrs are formed due to plastic deformation of electrical sheets. Burr formed due to punching on the edges of laminated sheets impairs the insulation of adjacent sheet and make random galvanic contacts during the pressing of stacked sheets. The effect of circulating current occurs if the burrs occur on the opposite edges of the stacks of laminated sheets and incase of bolted or wielded sheets, induced current return through it. This induced current causes the additional losses in electrical machine. The existence of surface current on the boundary between two insulated regions causes discontinuity of tangential component of magnetic field. Hence, based on this principle, the boundary layer model was developed to study the additional losses due to galvanic contacts formed by burred edges. The boundary layer model was then coupled with 2-D finite element vector potential formulation and compared with fine mesh layer model. Fine mesh layer model consists of finely space discretized 950028 second order triangular elements. The losses were computed from two models and were obtained similar at 50 Hz. The developed boundary layer model can be further used in electrical machines to study additional losses due to galvanic contacts at the edges of stator cores.

The detection of through-hole with a diameter of 1.6mm and the consistency of its signal are the basic evaluation indicators to decide whether the drill pipe is available. The relative position of the defect and sensor is random during the actual detection, causing the difficulty that it is hard to ensure the signal consistency of through-hole detection. This paper begins with the analytical model of magnetic field leakage (MFL) for through-hole, using the coil to detect the tangential component of the through-hole MFL, with the single sensors signal shown by simulation. Experiments and numerical simulation were done for the 1.6mm through-hole to acquire the effective coverage of its MFL and the suitable spacing of array sensors. The experimental results are consistent with simulation, which could be theoretical guidance for the optimization of array sensors.

To explore a way to characterize fatigue damage degree of ferromagnetic materials by metal magnetic memory testing (MMMT), tension-compression fatigue test of specimens with different stress concentration factors made of 45% C steel were carried out. Both normal and tangential component of magnetic memory signals, Hp(y) and Hp(x), of specimens under different fatigue cycles were measured by EMS-2003 and RM-1 magnetic memory testing apparatus respectively. The results show that, the gradient variation of Hp(y) signals during the fatigue test is similar to each other, but the gradient value is different due to the different stress concentration factors. And so is the relative peak value of Hp(x) signals. Both gradient of Hp(y) and relative peak value of Hp(x) can be used to distinguish the stress concentration degree of specimens.

In order to predict rockfalls, the failure of rock joints is studied. Considering these failures as constitutive instabilities, the second order work criterion is used, since it explains all divergence instabilities (flutter insta-bilites are excluded). The bifurcation domain and the loading directions of instabilities, which fulfil the criterion, are determined for any piecewise linear constitutive relation. The instability of rock joints appears to be ruled by coupling features of the behaviour (e.g., dilatancy). Depending on the loading parameters, instabilities can lead to failure, even before the plastic limit criterion. Results for two given constitutive relations illustrate the approach. Some given loading paths are especially considered. Constant volume (undrained) shear and τ-constant paths are stable or not depending on the link between the deviatoric stress and strain along undrained paths, as found for soils. Some unstable loading paths are illustrated. Along these paths, failure before plastic limit criterion is possible. The corresponding failure rules are determined. Rock slopes present different types of defects at all scale. We call rock joints the discontinuities (e.g., in mechanical properties) at macroscopic scale and we assume that rock joints have the greatest influence on the stabilities of rock slopes. This is why geomechanical stability analyses need to represent accurately rock joints' failures. We thus focus on the mechanical behaviour of such joints and, in the framework of a 2D assumption, only four scalar variables will be used to describe the corresponding mechanical state. Two stress components are considered : one normal, denoted σ (considered positive in compression), and one tangential, denoted τ. On the other hand, relative displacements oc-curing along the joint are considered, with a normal component u (positive in compression) and a tangential component γ. We define here, as in the general plasticity theory that failure is obtained when relative displacements along the joint (that we can call "deformation", from a general point of view) go on under a constant loading, by the existence of limit stress states. Failure of rock joint is obtained for example during constant normal load (CNL) shearings, defined by a constant value of σ, once τ reaches a peak or a plateau [1, 2, 3, 4] : under these conditions γ increases continuously while stresses are constant. This situation in a rock slope would trigger rockfalls. Such analysis of failure introduces directly the concept of limit stress states, for which stresses do not vary anymore : dσ " pdτ, dσq " 0, while relative displacements still evolve : dl " pdγ, duq ‰ 0.

This paper proposes a new method for increasing efficiency transmission of electricity by cables, based on the change of Poynting Vector value, using an insulation electrically polarized by current conduction. The idea is to increase the tangential component of Poynting Vector, namely the density of electric power transmitted to consumers, by using special insulation of the cable which is polarized under the action of current conduction, increasing the radial component of the electric field at cable surface. The advantages of the method are: to increase the efficiency transmission of electric energy, to reduce the voltage drops, to decrease the losses due the Joule-Lenz effect, to increase the lifetime of the cable. This method is useful in the case of kilometers or tens of kilometers length of cable.

In this paper, we propose an efficient finite element method with impedance transmission boundary condition (ITBC) to significantly improve the numerical solutions of the optical waveguide problems. It utilizes the curl-conforming linear tangential and quadratic normal (LT/QN) edge elements to expand the tangential component of the electric field, and the second order nodal-based scalar basis functions to expand the longitudinal component. Furthermore, to avoid the very fine spatial discretization of thin lossy sheet, ITBC has been proposed for the FEM formulations. The graphene plasmonic waveguide verify that the FEM with ITBC technique has high efficiency.

International audience; This article proposes a global harmonic analysis of normal and tangential field components in air gap of multiphase bearingless permanent magnet motor topology to determine the radial force. This allows establishing the semi-analytical expressions of the radial force considering the location of field sources. The accuracy of the model is verified by full finite element method model using a statistic approach. An important result of this approach of modeling is that it permits to choose the most convenient topology for the bearingless permanent magnet motors by taking into account the location of the field sources in stator and rotor. In addition, the semi-analytic model allows predicting the force waveforms according to the stator and rotor topologies. The analysis of two different rotor topologies is carried out and it highlights the influence of the tangential component of the air-gap magnetic field on the motor performances. Moreover, the influence of the radial or parallel magnetization of the rotor magnet on the force ripples is discussed. The reduction of CPU time using the semi-analytical model makes it suitable to be implemented in a design optimization process.

The novel sheet-bulk metal forming (SBMF) technology allows the production of solid metal components with various functional design features out of flat sheet specimens. However, due to the high working pressures arising during the forming process the efficiency of SBMF is tightly related to the tool service life, which is mainly limited by die wear. In the forming processes involving high contact pressures (e.g. SBMF) the influence of contact normal stresses on the die wear can be overestimated. In order to provide a realistic estimation of the die wear, the shear friction stress must be considered. The presented paper introduces a die wear model that intends the tangential component of contact stress and its implementation in the commercial FE code.

The forces that occur in the wheel–rail interface significantly affect vehicle dynamics, especially in the longitudinal direction. Conventionally, the tangential component of the force exchanged between the rail and the wheel is expressed as the product of the normal component of the force, and the so-called adhesion coefficient. This ratio depends on several parameters that are usually summarized in the term ‘adhesion conditions’. When the adhesion conditions are degraded (for example, in cases of rain, fog, ice, dead leaves, etc.), and the vehicle is accelerating or braking, pure rolling conditions between the wheels and the rails do not hold any more, and macroscopic sliding occurs on one or more of the wheels. The aim of this work is to identify a relationship between adhesion coefficient and some parameters, namely wheel sliding and train speed, starting from a set of experimental measurements, obtained from test runs conducted with artificially degraded adhesion conditions.

The possibility of reducing the influence of both the gap in a transducer-object combined circuit and the shape of tested objects on the results of local measurements of their coercive force is investigated. It is shown that additional measurements of the maximum magnetic flux in the circuit and the tangential component of the magnetic field on the surface of the tested area of the object, which is retained after the magnetizing current is turned off, allow a substantial decrease in the corre- sponding errors. © Pleiades Publishing, Ltd., 2012.

Fatigue damage degree of crankshaft remanufacturing core was studied based on Metal Magnetic Memory Testing. Bending fatigue test of crankshaft remanufacturing core was conducted on the resonant fatigue test rig and variations of two-dimensional magnetic memory signal distribution in crankshaft pin fillets were studied at different bending fatigue cycle. Experimental research shows that distributions of Hp(x) signals, namely, tangential component of spontaneous stray field and Hp(y) signals, namely, normal component of spontaneous stray field in crankshaft pin fillets have no obvious change with loading cycle when no crack initiation and propagation occur in crankshaft pin fillets. Characteristics of Hp(x) and Hp(y) signal both show dynamic variations when crack in crankshaft pin fillets initiates and extends at medium rate or high rate. Metal Magnetic Memory Testing is a dynamic method for monitoring fatigue crack propagation in crankshaft.

As the structure component of the spray anchor bracing system, at present the structure calculation method of the longitudinal lattice girder use more simple beam, continuous beam. In order to further research the calculation theory and applicability of the longitudinal lattice girder structure, making the calculation method reflect the mechanical properties of the longitudinal lattice girder accurately, this paper through the use of ANSYS finite element numerical simulation method[1], and the improved method of Winkler[3], considering the impact of the tangential component of the anchor rod axial force, and considering the impact of excavation conditions of the deep foundation pit actual, compare the calculation results of the internal force of the longitudinal lattice girder, concluded the optimization calculation method of the longitudinal lattice girder and the applicability.

A dynamic overmodulation strategy for fast dynamic torque control in direct torque control (DTC)-hysteresis-based induction machine is proposed. The fastest dynamic torque response with a six-step mode can be achieved in the proposed method by switching only the most optimized voltage vector that produces the largest tangential component to the circular flux locus. This paper also discusses the performance of dynamic torque control in basic DTC in order to justify on how the proposed selected voltage vector results in excellent dynamic torque performance. The main benefit of the proposed method is its simplicity, since it only requires a minor modification to the conventional DTC-hysteresis-based structure and does not require a space vector modulator. To verify the feasibility of the proposed dynamic overmodulation strategy, simulation and experimentation, as well as comparison with the conventional DTC scheme, are carried out. Results showed a significant improvement in the dynamic torque response when compared to the conventional DTC-hysteresis-based method.

Deforming a cracked magnetoelastic body in a magnetic field induces a perturbed magnetic field around the crack. The quantitative relationship between this perturbed field and the stress around the crack is crucial in developing a new generation of magnetism-based nondestructive testing technologies. In this paper, an analytical expression of the perturbed magnetic field induced by structural deformation of an infinite ferromagnetic elastic plate containing a centered crack in a weak external magnetic field is obtained by using the linearized magnetoelastic theory and Fourier transform methods. The main finding is that the perturbed magnetic field intensity is proportional to the applied tensile stress, and is dominated by the displacement gradient on the boundary of the magnetoelastic solid. The tangential component of the perturbed magnetic-field intensity near the crack exhibits an antisymmetric distribution along the crack that reverses its direction sharply across its two faces, while the normal component shows a symmetric distribution along the crack with singular points at the crack tips.

Spot welding is widely used for joining metal plates. However, a highly reliable monitoring method is needed to weld a robust structure. For this purpose, we developed a magnetic flux leakage (MFL) system using a magnetoresistive (MR) sensor for nondestructive spot-weld inspection. The magnetic flux is induced between two joined plates, and the magnetic flux leakage with a tangential component parallel to the plate surface is measured. A magnetic image at the spot-welding part is obtained by two-dimensional scanning. The connected diameter of the nugget and the maximum shear load are measured after the magnetic measurement to investigate their interrelationship. The results show that the nondestructive magnetic flux leakage test shows a good correlation with the destructive shear test.

The spatial behavior of the components of a pressure tensor inside the filled wedge-shaped cavity of a solid, which was calculated in a previous communication, is analyzed. The approximation for introducing and studying the disjoining pressure in a wedge-shaped film is developed.

A method that allows the effect of a gap on the results of coercimetric quality control of articles to be decreased that is based on taking properties of an attachable transducer into account is proposed. The properties of a transducer are taken into account using a preliminary recorded demagnetization line of an attachable electromagnet whose magnetic circuit is not closed by an article. It is shown that the tangential component of the magnetic field of an inspected article during magnetization reversal along this line equals the coercive force of the article if its cross section does not exceed the electromagnet cross section.

Theoretical approach to the solution of georadiolocation (inverse) problem of reconstructing the antenna current and the permittivity of the underlying surface, based on the measurements of the field propagating along the Earth℉s surface, is proposed. An expression for the tangential component of the electric field of the surface wave from a transmitting antenna lying in the plane of discontinuity of two homogeneous media is expressed in terms of the Laplace function Ŵ(q, ζ) of two complex arguments for any discontinuity parameters. The function Ŵ(q, ζ) is presented as series, which make it possible to calculate rapidly the values of Ŵ(q, ζ) and investigate its analytic properties. The inverse Laplace transform is performed by integrating the function Ŵ(q, ζ) over closed contours. The corresponding integrals are proper in this case, due to which the calculation time greatly decreases in comparison with the Fourier transform. When the permittivity dispersion can be neglected, the tangential component of the surface wave is algebraically expressed in terms of the function Ŵ(q, ζ). This circumstance allows one to decrease the time for calculating the surface wave at a specified point to several milliseconds and determine both the current through the transmitting antenna and the permittivity of the underlying surface for a few seconds.

Based on general profile theory, the basic scroll profiles are presented in the form of polynomial or simple trigonometric functions. For a scroll fluid machine with an arbitrary number of scroll wraps on its individual scroll, the phase difference between adjacent scroll profiles is defined as the characteristic angle and its scroll pitch lines are classified into A-type and B-type. The normal thickness and the all-thickness of scroll wrap are also defined. The number of scroll wraps on one scroll, the orbiting radius, the maximum tangential component of general profile, the thickness coefficient, and the height of scroll wrap are determined as the basic parameters which can demonstrate basic characteristics of scroll fluid machine. It is more reasonable to employ involute of circle and double-wrap scroll, to specify a smaller orbiting radius and a smaller height under satisfaction of the basic requirement. According to the basic parameters proposed, scroll fluid machine is classified into small-parameter and large-parameter scroll fluid machines. In order to obtain the performance with higher working pressure and larger compression ratio, it may be a significant work to study the large-parameter scroll fluid machine.

Insertion of embedded electrodes (EEs) inside a MV XLPE cable termination strongly affects electric field around the termination and accordingly must be carefully considered. In this paper, influence of embedded electrodes on voltage distribution in some constructions of the 20 kV cable terminations was analyzed. Different options were considered for a specific number of the EEs along the cable insulation surface, taking into account possible effects of floating or grounded EEs, their different position and separation. In every option, a basic method of stress relieving with resistive layer over the end of semi conducting screen and primary cable insulation was applied. Reference design was a cable termination without EE. Its voltage distribution, total electric field and tangential component were observed for comparison. The stress relief materials, in the shape of pads or tubes, were used. Their properties were kept the same in all constructions. Voltage distribution was monitored, starting from the end of the primary cable insulation in the vicinity of the phase conductor and ending at the cable insulation attached to the semiconducting screen end at ground potential. The different design options were experimentally verified. .

In this paper, we present simulation results and analysis of 3-D magnetic flux leakage (MFL) signals due to the occurrence of a surface-breaking defect in a ferromagnetic specimen. The simulations and analysis are based on a magnetic dipole-based analytical model, presented in a previous paper. We exploit the tractability of the model and its amenability to simulation to analyze properties of the model as well as of the MFL fields it predicts, such as scale-invariance, effect of lift-off and defect shape, the utility of the tangential MFL component, and the sensitivity of MFL fields to parameters. The simulations and analysis show that the tangential MFL component is indeed a potentially critical part of MFL testing. It is also shown that the MFL field of a defect varies drastically with lift-off. We also exploit the model to develop a lift-off compensation technique which enables the prediction of the size of the defect for a range of lift-off values.

Finite-element analysis (FEA) was performed for bicycle helmets making oblique impacts with a road surface, to evaluate the linear and rotational accelerations of the headform. Helmet rotation on the head was considered, modelling the helmet and retention strap interactions with the headform. The effects of frictional parameters on the response were explored, and parameters selected to reproduce experimental results. Predictions were made for two helmets, for a range of impact locations and tangential velocities. The design method for the peak headform linear acceleration was confirmed; it was hardly affected by the tangential component of the impact velocity. The peak headform rotational acceleration was investigated as a function of the helmet geometry, impact sites and velocities and the contributing mechanisms established.

We propose a procedure for full characterization of rectangular surface-breaking cracks based on measurements of only one tangential component of the magnetic field with the magnetic flux leakage (MFL) technique. The parameters of interest include orientation, length, and depth of the cracks. We assume that the length and the depth of the investigated cracks are much larger than the crack width, so that the variation of the MFL response with respect to the width is negligible. Our procedure employs fast direct methods that provide reliable estimation of the crack parameters in three separate consecutive steps. We propose denoising and correction techniques as well. We confirmed the accuracy of the methods by simulations based on the finite-element method (FEM) as well as by experimental MFL observations. A procedure is proposed for full characterization of rectangular surface breaking cracks based on measurements of only one tangential component of the magnetic field with the magnetic flux leakage (MFL) technique. The parameters of interest include orientation, length and depth of the cracks. We assume that the length and the depth of the investigated cracks are much larger than the crack width such that the variation of the MFL response with respect to the width is negligible. The proposed procedure employs fast direct methods which provide reliable estimation of the crack parameters in three separate consecutive steps. De-noising and correction techniques are proposed as well. The accuracy of the proposed estimation methods is examined via simulations based on the finite element method (FEM) as well as experimental MFL data.