Electromagnetic Part Research Articles

An Optimization of the FPGA Based Wavelet Trigger in Radio Detection of Cosmic Rays

Experiments that observe coherent radio emission from extensive air showers induced by ultra-high energy cosmic rays are designed for a detailed study of the development of the electromagnetic part of air showers. Radio detectors can operate with 100% up time as e.g. surface detectors based on water-Cherenkov tanks. They are being developed for ground-based experiments (e.g. the Pierre Auger Observatory) as another type of air shower detector in addition to the fluorescence detectors, which operate with only ~10% of duty in dark nights. The radio signals from air showers are caused by the coherent emission due to geomagnetic radiation and charge excess processes. Currently used self-triggers in radio detectors often generate a dense stream of data, which is analyzed afterwards. Huge amounts of registered data requires a significant man-power for the off-line analysis. An improvement of the trigger efficiency becomes a relevant factor. In this work, Morlet wavelets with various scaling factors were used for an analysis of real data from the Auger Engineering Radio Array and for an optimization of the utilization of the resources in an FPGA. The wavelet analysis showed that the power of events is concentrated mostly in a limited range of the frequency spectrum (consistent with a range imposed by the input analog band-pass filter). However, we found several events with suspicious spectral characteristics, where the signal power is spread over the full band-width sampled by a 200 MHz digitizer with significant contribution of very high and very low frequencies. These events may not origin from cosmic ray showers but can be human-made contaminations. The engine of the wavelet analysis can be implemented into the modern powerful FPGA and can remove suspicious events on-line to reduce the trigger rate.

Magnetic-assisted triboelectric nanogenerators as self-powered visualized omnidirectional tilt sensing system.

The triboelectric nanogenerator (TENG) is a promising device in energy harvesting and self-powered sensing. In this work, we demonstrate a magnetic-assisted TENG, utilizing the magnetic force for electric generation. Maximum power density of 541.1 mW/m2 is obtained at 16.67 MΩ for the triboelectric part, while the electromagnetic part can provide power density of 649.4 mW/m2 at 16 Ω. Through theoretical calculation and experimental measurement, linear relationship between the tilt angle and output voltage at large angles is observed. On this basis, a self-powered omnidirectional tilt sensor is realized by two magnetic-assisted TENGs, which can measure the magnitude and direction of the tilt angle at the same time. For visualized sensing of the tilt angle, a sensing system is established, which is portable, intuitive, and self-powered. This visualized system greatly simplifies the measure process, and promotes the development of self-powered systems.

Efficient frequency-transient co-simulation of coupled heat-electromagnetic problems

BackgroundWith the recent advent of inductive charging systems all major automotive manufacturers develop concepts to wirelessly charge electric vehicles. Efficient designs require virtual prototyping that accounts for electromagnetic and thermal fields. The coupled simulations can be computationally very costly. This is because of the high frequencies in the electromagnetic part. This paper derives a mixed frequency-transient model as approximation to the original problem. We propose a co-simulation such that the electromagnetic part is simulated in the frequency domain while the thermal part remains in time domain.ResultsThe iteration scheme for the frequency-transient model is convergent for high frequency excitation. The error bound improves quadratically with increasing frequency.ConclusionsThe frequency-transient model is very efficient for coupled heat-electromagnetic simulations since the time scales typically differ by several orders of magnitude. The time steps of the full system can be chosen according to the heat subsystem only.MSC: 35K05, 35Q61, 65Z05, 78A25, 78M12, 80M25.

State Space-Vector Model of Linear Induction Motors

This paper presents the state space-vector dynamic model of the linear induction motor (LIM) taking into consideration the dynamic end effects. Starting from the space-vector equivalent circuit of the LIM, the complete set of space-vector equations has been deduced. Afterward, first the so-called voltage and current flux models have been written, from which the complete state space-vector representation has been given. The complete thrust expression including the end-effect braking force has also been introduced in the model. The complete state space-vector model, electromagnetic and mechanical part, has been implemented in numerical simulation and has been validated by comparing the results with those obtainable with a finite-element analysis and experiments. Results show that, even with a machine with a limited presence of the dynamic end effects, the adoption of a this model permits a better estimation of both the electric quantities, e.g., inductor current, and the mechanical quantities, e.g., linear speed, with respect to the classic rotating induction motor model.

Fast computation of electromagnetic scattering characteristics from conducting targets using modified-physical optics and graphical electromagnetic computing

A novel high-frequency radar cross section prediction method is introduced to solve the scattering from electrically large conductive target. It can be realized by combining a modified-vector physical optics algorithm and a graphical electromagnetic computing algorithm. In consideration of the traditional physical optics algorithm which needs to compute the edge diffraction, the radar cross section of the target cannot be calculated directly, but it is needed to first calculate the diffraction contribution, then to add the scattering contribution, therefore the radar cross section of the target can be finally obtained. By using the improved graphical electromagnetic computing, the surface normals, thus the surface current, can be directly corrected. Therefore the diffraction at the edges is taken into account, thereby improving the efficiency of the algorithm. The central processing unit running time involves only the time needed to compute the electromagnetic part, with leaving the geometric part to the graphics hardware. The line integrals are computed over an arbitrary shape in real time. Numerical results demonstrate the good accuracy and efficiency of the modified method.

A comprehensive dynamic modeling approach for giant magnetostrictive material actuators

In this paper, a comprehensive modeling approach for a giant magnetostrictive material actuator (GMMA) is proposed based on the description of nonlinear electromagnetic behavior, the magnetostrictive effect and frequency response of the mechanical dynamics. It maps the relationships between current and magnetic flux at the electromagnetic part to force and displacement at the mechanical part in a lumped parameter form. Towards this modeling approach, the nonlinear hysteresis effect of the GMMA appearing only in the electrical part is separated from the linear dynamic plant in the mechanical part. Thus, a two-module dynamic model is developed to completely characterize the hysteresis nonlinearity and the dynamic behaviors of the GMMA. The first module is a static hysteresis model to describe the hysteresis nonlinearity, and the cascaded second module is a linear dynamic plant to represent the dynamic behavior. To validate the proposed dynamic model, an experimental platform is established. Then, the linear dynamic part and the nonlinear hysteresis part of the proposed model are identified in sequence. For the linear part, an approach based on axiomatic design theory is adopted. For the nonlinear part, a Prandtl–Ishlinskii model is introduced to describe the hysteresis nonlinearity and a constrained quadratic optimization method is utilized to identify its coefficients. Finally, experimental tests are conducted to demonstrate the effectiveness of the proposed dynamic model and the corresponding identification method.

Study on Magnetorheological Fluid Damper

Magnetorheological Fluid Damper has recently received considerable attention. This paper is focused in typical models, the strongpoints and application status of magnetorheological damper. In the meantime, the paper introduce the basic working principle of the smart passive damper using magnetorlogical fluid damper and the Faraday law how to be used in the magnetorlogical fluid damper with the electromagnetic induction part.

Research on the On-Line Monitoring System for Partial Discharge of Cable Joint

This paper introduces an on-line monitoring system for partial discharge of 10kV cable joint based on LabVIEW. It calculates transfer characteristic of wideband current transformer for monitoring partial discharge current after analyzing the mechanism of production of partial discharge. The proposed current transformer can restrain the noise signal efficiently in electromagnetic induction part. Since the on-line monitoring system was installed in transformer substation, the LabVIEW monitoring platform can keep a lookout over partial discharge current of cable joint constantly. It can monitor the cable joint accurately.

An optimization of the FPGA/NIOS adaptive FIR filter using linear prediction to reduce narrow band RFI for the next generation ground-based ultra-high energy cosmic-ray experiment

The electromagnetic part of an extensive air shower developing in the atmosphere provides significant information complementary to that obtained by water Cherenkov detectors which are predominantly sensitive to the muonic content of an air shower at ground. The emissions can be observed in the frequency band between 10 and 100MHz. However, this frequency range is significantly contaminated by narrow-band RFI and other human-made distortions. The Auger Engineering Radio Array currently suppresses the RFI by multiple time-to-frequency domain conversions using an FFT procedure as well as by a set of manually chosen IIR notch filters in the time-domain. An alternative approach developed in this paper is an adaptive FIR filter based on linear prediction (LP). The coefficients for the linear predictor are dynamically refreshed and calculated in the virtual NIOS processor. The radio detector is an autonomous system installed on the Argentinean pampas and supplied from a solar panel. Powerful calculation capacity inside the FPGA is a factor. Power consumption versus the degree of effectiveness of the calculation inside the FPGA is a figure of merit to be minimized. Results show that the RFI contamination can be significantly suppressed by the LP FIR filter for 64 or less stages.

Seismoelectric wave propagation numerical modelling in partially saturated materials

To better understand and interpret seismoelectric measurements acquired over vadose environments, both the existing theory and the wave propagation modelling programmes, available for saturated materials, should be extended to partial saturation conditions. We propose here an extension of Pride's equations aiming to take into account partially saturated materials, in the case of a water-air mixture. This new set of equations was incorporated into an existing seismoelectric wave propagation modelling code, originally designed for stratified saturated media. This extension concerns both the mechanical part, using a generalization of the Biot-Gassmann theory, and the electromagnetic part, for which dielectric permittivity and electrical conductivity were expressed against water saturation. The dynamic seismoelectric coupling was written as a function of the streaming potential coefficient, which depends on saturation, using four different relations derived from recent laboratory or theoretical studies. In a second part, this extended programme was used to synthesize the seismoelectric response for a layered medium consisting of a partially saturated sand overburden on top of a saturated sandstone half-space. Subsequent analysis of the modelled amplitudes suggests that the typically very weak interface response (IR) may be best recovered when the shallow layer exhibits low saturation. We also use our programme to compute the seismoelectric response of a capillary fringe between a vadose sand overburden and a saturated sand half-space. Our first modelling results suggest that the study of the seismoelectric IR may help to detect a sharp saturation contrast better than a smooth saturation transition. In our example, a saturation contrast of 50 per cent between a fully saturated sand half-space and a partially saturated shallow sand layer yields a stronger IR than a stepwise decrease in saturation.

Coupling Simulation and Characteristic Analysis of Pure Water High-Speed On-Off Valve

The paper introduces the structure and operating principle of two-position three-way pure water high-speed solenoid on-off valve, establishes the mathematical model of on-off valve, obtains performance parameters of electromagnet through Ansoft simulation, imports the performance parameters of electromagnet into the solenoid on-off valve simulation model in AMESim, and realizes the coupling simulation among electromagnetic circuit, mechanical part and hydraulic system, so as to improve simulation precision and achieve relatively correct static-dynamic simulation results of high-speed solenoid on-off valve.

Performance enhancement of a rotational energy harvester utilizing wind-induced vibration of an inclined stay cable

In this paper, an innovative strategy for improving the performance of a recently developed rotational energy harvester is proposed. Its performance can be considerably enhanced by replacing the electromagnetic induction part, consisting of moving permanent magnets and a fixed solenoid coil, with a moving mass and a rotational generator (i.e., an electric motor). The proposed system is easily tuned to the natural frequency of a target structure using the position change of a proof mass. Owing to the high efficiency of the rotational generator, the device can more effectively harness electrical energy from the wind-induced vibration of a stay cable. Also, this new configuration makes the device more compact and geometrically tunable. In order to validate the effectiveness of the new configuration, a series of laboratory and field tests are carried out with the prototype of the proposed device, which is designed and fabricated based on the dynamic characteristics of the vibration of a stay cable installed in an in-service cable-stayed bridge. From the field test, it is observed that the normalized output power of the proposed system is 35.67 mW (m s−2)−2, while that of the original device is just 5.47 mW (m s−2)−2. These results show that the proposed device generates much more electrical energy than the original device. Moreover, it is verified that the proposed device can generate sufficient electricity to power a wireless sensor node placed on a cable under gentle–moderate wind conditions.

Finite Element Analysis and Experimental Study of an Electromagnetic Shell Part with Flow Control Forming

In this paper, an electromagnetic shell part was studied with the design of die, simulation and the flow control forming (FCF) method. The important technology of FCF was the design of cavity die to control metal flow. The simulation results indicate that pyramidal faces of cavity die exerted a significant influence on qualities of parts. The simulation results also revealed that the effective stresses of the sheet were inhomogeneous and the distributions of the equivalent stress were lamellar with obvious gradients. Experimental results show that steel sheet (08Al) could be formed in one step into intricate shapes at room temperature. This confirmed that FCF is a safe, clean and practical method for the near net forming of parts.

FPGA/NIOS Implementation of an Adaptive FIR Filter Using Linear Prediction to Reduce Narrow-Band RFI for Radio Detection of Cosmic Rays

We present the FPGA/NIOS implementation of an adaptive finite impulse response (FIR) filter based on linear prediction to suppress radio frequency interference (RFI). This technique will be used for experiments that observe coherent radio emission from extensive air showers induced by ultra-high-energy cosmic rays. These experiments are designed to make a detailed study of the development of the electromagnetic part of air showers. Therefore, these radio signals provide information that is complementary to that obtained by water-Cherenkov detectors which are predominantly sensitive to the particle content of an air shower at ground. The radio signals from air showers are caused by the coherent emission due to geomagnetic and charge-excess processes. These emissions can be observed in the frequency band between 10-100 MHz. However, this frequency range is significantly contaminated by narrow-band RFI and other human-made distortions. A FIR filter implemented in the FPGA logic segment of the front-end electronics of a radio sensor significantly improves the signal-to-noise ratio. In this paper we discuss an adaptive filter which is based on linear prediction. The coefficients for the linear predictor (LP) are dynamically refreshed and calculated in the embedded NIOS processor, which is implemented in the same FPGA chip. The Levinson recursion, used to obtain the filter coefficients, is also implemented in the NIOS and is partially supported by direct multiplication in the DSP blocks of the logic FPGA segment. Tests confirm that the LP can be an alternative to other methods involving multiple time-to-frequency domain conversions using an FFT procedure. These multiple conversions draw heavily on the power consumption of the FPGA and are avoided by the linear prediction approach. Minimization of the power consumption is an important issue because the final system will be powered by solar panels. The FIR filter has been successfully tested in the Altera development kits with the EP4CE115F29C7 from the Cyclone IV family and the EP3C120F780C7 from the Cyclone III family at a 170 MHz sampling rate, a 12-bit I/O resolution, and an internal 30-bit dynamic range. Most of the slow floating-point NIOS calculations have been moved to the FPGA logic segments as extended fixed-point operations, which significantly reduced the refreshing time of the coefficients used in the LP. We conclude that the LP is a viable alternative to other methods such as non-adaptive methods involving digital notch filters or multiple time-to-frequency domain conversions using an FFT procedure.

Electromagnetic Heating of Heavy Oil and Bitumen: A Review of Experimental Studies and Field Applications

Viscosity is a major obstacle in the recovery of low API gravity oil resources from heavy oil and bitumen reservoirs. While thermal recovery is usually considered the most effective method for lowering viscosity, for some reservoirs introducing heat with commonly implemented thermal methods is not recommended. For these types of reservoirs, electromagnetic heating is the recommended solution. Electromagnetic heating targets part of the reservoir instead of heating the bulk of the reservoir, which means that the targeted area can be heated up more effectively and with lower heat losses than with other thermal methods. Electromagnetic heating is still relatively new and is not widely used as an alternate or addition to traditional thermal recovery methods. However, studies are being conducted and new technologies proposed that could help increase its use. Therefore, the objective of this study is to investigate the recovery of heavy oil and bitumen reservoirs by electromagnetic heating through the review of existing laboratory studies and field trials.

A low frequency tunable hybrid generator

A serious of experimental tests on a commercial brass reinforced PZ bimorph cantilever of the type 5H4E were carried out in a vibration laboratory using a Labview of NI make as instrumentation and control system. Originally the bender acted as a tunable PZ generator, using perforated steel shims as a proof mass. The generator was converted to a hybrid generator by adding ring magnets to its other surface and making them working as part of an electromagnetic generator in addition of being a proof mass. Two arrangement of the electromagnetic generator were investigated at a frequency of (33) Hz which is the resonance frequency at max power of the original PZ generator. By using a shaker the cantilever was vibrated and set into acceleration of (0.25) g rms during all stages as this value was considered to be available and acceptable in balanced large rotating machines in industry. The hybrid generator produced (187) μW for max power, (14.8) Vrms for max OCV, and (8.26) Vrms for max on load voltage for the PZ part, while the electromagnetic part produced max (70) Vrms, (490) μW for arrangement (1) and (34) Vrms, (116) μW for arrangement (2) on no load condition and at the same frequency. The experimental results obtained from the electromagnetic generator are acceptable compared with theory.

A Hybrid Structure of Dual Stators and a Pneumatic Spring for Resonance Control in an Air Mount

An active device using electromagnetic forces was constructed and examined for the purpose of minimizing the resonance in air mounts of clean rooms. The air mounts are vulnerable to low-frequency resonance due to heavy weight and low stiffness. A hybrid structure of the active device, composed of pneumatic and electromagnetic parts, was developed and tested. The pneumatic parts in the device support heavy weights under the air mounts, and the electromagnetic parts reduce the resonance. The electromagnetic parts are composed of dual stators and an armature, which surround the pneumatic parts. The resonance can decrease when electromagnetic forces are generated in the gaps between the stators and the armature. Four active devices were installed under a 3-ton surface plate for a vibration test apparatus. The vibration was detected by eddy-current sensors. Discrete P Control logic was based on displacement, and embedded in a C6713 DSP. The results from impact tests show that the peak magnitude in the resonance frequency can be reduced to –10 dB.

Status of the ATLAS Liquid Argon calorimeter and its performance after two years of LHC operation

The ATLAS detector is designed to study proton–proton collisions produced at the Large Hadron Collider (LHC) at CERN. Its calorimeter system, for the electromagnetic and forward part and for a fraction of the hadronic part, is made of liquid argon sampling calorimeters. During the 2011 data taking period, ATLAS operated with an excellent efficiency and recorded more than 5fb−1 integrated luminosity of 7TeV center of mass energy proton–proton collisions. The ATLAS Liquid Argon calorimeters played a significant role in this achievement. Its main features are first described. Then, some of its performances over the past two years are given. Highlights are put on its operation, calibration, stability and data taking efficiency, as well as on the related physics performances.

Analysis of Doppler effect of moving conducting surfaces with Lorentz-FDTD method

To analyze scattering fields from moving conducting bodies, a novel Lorentz finite-difference time-domain (FDTD) method is proposed in this paper. The transformation formulas of electromagnetic field parts, space parts, and time variable are gained by using Lorentz transformation between the rest and the moving reference frame. To calculate the scattering fields from moving conducting bodies, the total-field–scattered-field boundary condition is set up to introduce an incident plane wave in the moving reference frame. Using the interpolation method, the relation between electromagnetic fields in the moving reference frame and that of the related grids in the rest is estimated. Using the proposed Lorentz-FDTD method analyze the scattering fields from one-dimensional moving conducting surface. Thus, variations of the amplitude and frequency of scattering fields with the moving conducting surface speed are considered. Caused by the moving conducting surface, the amplitude and frequency of incident plane wave suffer a modulation shift. Numerical results are in a good agreement with analytical results for the discussed case.

Study on the High-Efficiency Smoothness Grinding of Soft Magnetic Powder Cores

Soft magnetic powder cores are materials manufactured by pressing pure iron powder covered with insulating film into shape. These are widely known soft magnetic materials which are used as essential electromagnetic conversion parts in automobiles and household appliances. In recent years, demand for higher magnetic properties and dimensional precision has been growing with respect to soft magnetic powder cores. It has therefore become necessary to develop a high-efficiency, high-precision finishing method. The issues to be addressed with regard to this kind of method are: (1) the pure iron used in these materials displays ductility resulting in burring and cohesion to machining tools, (2) these materials are green compacts with low binding forces between powder particles and high tendencies towards cracking and gouging, and (3) these materials possess residual pores at levels of several percent thus resulting in microscopically intermittent processing which causes heavy machining tool wear. We have solved these issues through the development of a super-smooth finishing method designed for soft magnetic powder cores.