Field Strength Measurements Research Articles

Research on intelligent near-power early warning system for mechanical vehicles

Base on the electric field strength measurement technology, an early warning system for a mechanical vehicle close to a high voltage electric wire is studied. By analyzing the influence of the distorted electric field, the correction matrix of the probe is obtained by comparing the standard value with the measured value, which greatly improves the correction matrix and the accuracy of the alarm. Through the signal conditioning at the signal collector, the data comparison judgment is realized.

Laboratory plasmas for high-energy astrophysics: A method to measure effective Landé g-factors

AbstractEffective Landé g-factors (geff) are fundamental quantities in order to derive stellar magnetic field intensities. The determination of geff involves both total angular momenta and Landé g-factors of the transition levels. Theoretical g-factors are generally adopted, and the corresponding geff, often quite different from the one obtained in laboratory, affects the accuracy on magnetic field strength measurements. In this work we discuss a method to experimentally determine geff for highly ionised species, based on high resolution spectropolarimetry applied to Electron Cyclotron Resonance laboratory plasmas.

Role of Austenitization Temperature on Structure Homogeneity and Transformation Kinetics in Austempered Ductile Iron

This paper considers the important factors of the production of high-strength ADI (Austempered Ductile Iron); namely, the austenitization stage during heat treatment. The two series of ADI with different initial microstructures were taken into consideration in this work. Experiments were carried out for castings with a 25-mm-walled thickness. Variable techniques (OM, SEM, dilatometry, DSC, Variable Magnetic Field, hardness, and impact strength measurements) were used for investigations of the influence of austenitization time on austempering transformation kinetics and structure in austempered ductile iron. The outcome of this work indicates that the austenitizing temperature has a very significant impact on structure homogeneity and the resultant mechanical properties. It has been shown that the homogeneity of the metallic matrix of the ADI microstructure strongly depends on the austenitizing temperature and the initial microstructure of the spheroidal cast irons (mainly through the number of graphite nodules). In addition, this work shows the role of the austenitization temperature on the formation of Mg–Cu precipitations in ADI.

A Hardware and Software Complex for Remote Monitoring of a High-Voltage Line Arrester under Operating Voltage

A hardware and software complex for remote monitoring of high-voltage line arresters (HVLAs) under operating voltage has been developed. The complex is a two-level distributed system with autonomous monitoring points. The main functional units of the complex are a block of current sensors, a registration and communication device, a self-contained power supply, a receiving base station, and an automated workplace (AWP). Apart from the total leakage current and number of operations, the complex registers the amplitude and duration of the HVLA lightning pulse. These parameters may be used for the assessment of the HVLA residual resources and making a decision as to the feasibility of its further operation. An optical sensor on the basis of a bismuth silicate crystal is used as a sensor of an impulse current; its operating principle is based on the Faraday linear magnetooptic effect. The advantage of the bismuth silicate crystal is the feasibility of the noncontact measurement of the pulse magnetic field strength, high temperature stability and high noise immunity. The standard of the wireless LoRa communication was selected for the transmission of information; its advantage is a high noise immunity, larger range of radio signal transmission (up to 10 km), low energy consumption, and high penetrating capacity penetrability. A solar battery with a standby power supply—a rechargeable battery—was selected as the self-contained power supply. Program modules for receiving and transmission of information and AWP were developed. The hardware and software system allow preventing the emergency situations on the high-voltage line, planning more service and repair operations more effectively and efficiently, and starting the operation of HVLAs based on technical conditions.

Cyclotron lines in highly magnetized neutron stars

Cyclotron lines, also called cyclotron resonant scattering features are spectral features, generally appearing in absorption, in the X-ray spectra of objects containing highly magnetized neutron stars, allowing the direct measurement of the magnetic field strength in these objects. Cyclotron features are thought to be due to resonant scattering of photons by electrons in the strong magnetic fields. The main content of this contribution focusses on electron cyclotron lines as found in accreting X-ray binary pulsars (XRBP) with magnetic fields on the order of several 1012Gauss. Also, possible proton cyclotron lines from single neutron stars with even stronger magnetic fields are briefly discussed. With regard to electron cyclotron lines, we present an updated list of XRBPs that show evidence of such absorption lines. The first such line was discovered in a 1976 balloon observation of the accreting binary pulsar Hercules X-1, it is considered to be the first direct measurement of the magnetic field of a neutron star. As of today (end 2018), we list 35 XRBPs showing evidence of one ore more electron cyclotron absorption line(s). A few have been measured only once and must be confirmed (several more objects are listed as candidates). In addition to the Tables of objects, we summarize the evidence of variability of the cyclotron line as a function of various parameters (especially pulse phase, luminosity and time), and add a discussion of the different observed phenomena and associated attempts of theoretical modeling. We also discuss our understanding of the underlying physics of accretion onto highly magnetized neutron stars. For proton cyclotron lines, we present tables with seven neutron stars and discuss their nature and the physics in these objects.

Investigation of the magnetic field sensing properties of a magnetic fluid clad microfiber knot sensor

The performance of a magnetic fluid clad microfiber knot–based magnetic field sensor was experimentally investigated in the presence of static and dynamic magnetic fields. In addition, the dependence of the sensor response on the orientation of the externally applied magnetic field has been evaluated. The results show that the proposed sensor provides simultaneous measurements of magnetic field strength and orientation by monitoring the resonant wavelength of microfiber knot. When the magnetic field was increased to 220 Gs, the maximum wavelength shift reached nearly 130 pm. To avoid rectification for alternating current magnetic field input, a direct current magnetic field bias was introduced to the sensor. Using this approach, the unipolar response was converted into a bipolar form, which produced an acceptable replica of the input sinusoidal waveform. These results provide great promise for the development of practical magnetic fluid-based fiber-photonic magnetic field devices.

Evaluation of the safety of users of active implantable medical devices (AIMD) in the working environment in terms of exposure to electromagnetic fields - Practical approach to the requirements of European Directive 2013/35/EU.

Electromagnetic fields (EMF) may cause malfunctions in electronic devices, in particular in active implantable medical devices (AIMD), along with discomfort or health hazards to users. The use of AIMD by workers is increasing (especially cardiac pacemakers, implantable cardioverter defibrillators and wearable insulin infusion pumps). Electromagnetic fields may be much stronger in the working environment than applied in basic immunity tests of AIMD (based on EN 60601- 1-2:2015 and EN 50527-1:2016). European Directive 2013/35/EU regarding the safety of workers exposed to EMF considered the AIMD users to be "workers at particular risk" who need an individual evaluation of EMF hazards. The study aimed at evaluating the safety of users of AIMD in medical and industrial working environments exposed to EMF. Near the common sources of strong EMF applied in medical and industrial use, the "standard safety distances" (SSD) for AIMD users were evaluated (i.e., distances from the EMF source, where exposure drops below limits from Recommendation 1999/519/EC and AIMD safety may be expected). The analysis is based on the results of measurements of magnetic and electric field strengths near 127 typical devices, in their normal use. The longest electric field related SSD was identified near dielectric sealers (up to 180 cm), and the longest magnetic field related SSD - near induction heaters (up to 450 cm). Electromagnetic fields related AIMD malfunctions need to be considered up to several meters from EMF sources. The "individual safety distance," that is sufficient to ensure the safety of a particular AIMD user may be significantly different (usually shorter) from the presented SSD, but needs to be considered in the context of detailed safety data from the AIMD manufacturer (if available). The labelling indicating the location of the area of a strong EMF increases safety of AIMD users in the work environment. Int J Occup Med Environ Health 2018;31(6):795-808.

The Eruption of a Prominence-carrying Coronal Flux Rope: Forward Synthesis of the Magnetic Field Strength Measurement by the COronal Solar Magnetism Observatory Large Coronagraph

From a magnetohydrodynamic (MHD) simulation of the eruption of a prominence hosting coronal flux rope, we carry out forward synthesis of the circular polarization signal (Stokes V signal) of the FeXIII emission line at 1074.7 nm produced by the MHD model as measured by the proposed COronal Solar Magnetism Observatory (COSMO) Large Coronagraph (LC) and infer the line-of-sight magnetic field BLOS above the limb. With an aperture of 150 cm, integration time of 12 min, and a resolution of 12 arcsec, the LC can measure a significant BLOS with sufficient signal to noise level, from the simulated flux rope viewed nearly along its axis with a peak axial field strength of about 10 G. The measured BLOS is found to relate well with the axial field strength of the flux rope for the height range of the prominence, and can discern the increase with height of the magnetic field strength in that height range that is a definitive signature of the concave upturning dipped field supporting the prominence. The measurement can also detect an outward moving BLOS due to the slow rise of the flux rope as it develops the kink instability, during the phase when its rise speed is still below about 41 km/s and up to a height of about 1.3 solar radii. These results suggest that the COSMO LC has great potential in providing quantitative information about the magnetic field structure of CME precursors (e.g. the prominence cavities) and their early evolution for the onset of eruption.

Path Loss Model Optimization Using Stochastic Hybrid Genetic Algorithm

In the context of modeling the propagation of mobile radio signals, optimizing the existing path loss model is largely required to precisely represent the actual propagation medium. In this paper, a hybrid tuning approach is proposed by merging the stochastic Weighted Least Square method and Genetic algorithm. The proposed hybrid optimization is employed to optimize the parameters of Cost 231 Hata propagation model and is validated by cellular field strength measurements at 900 MHz in the sub urban region. The hybrid optimization is compared with optimized results of Weighted Least Square method and Genetic algorithm. The least values of Mean Square error (0.2702), RMSE (0.4798) and percentage Relative error (3.96) justify the tuning precision of the hybrid method. The proposed optimization approach could be used by network service providers to improve the quality of service and in mobile radio network planning of 900 MHz band for 4G LTE services. Â

Elektrik alan seviyeleri ve halk sağlığı açısından değerlendirilmesi: Samsun şehir merkezi örneği

Objective: In parallel with technological developments, radio/TV transmitters, base stations, power lines, transformers, electrical household appliances and medical equipments have begun to take up more space in our daily lives, causing an increase in the electromagnetic fields (EMF) in our environments. Increasing demand for wireless systems has further led to more exposure to EMFs. Therefore, a more comprehensive understanding of the potential health consequences of electromagnetic field exposure has become ever more crucial. Method: In this study, short term electric field strength (E) measurements were taken in the Ilkadim, Canik and Atakum districts of Samsun province, at 152 different locations in the months of April, May and September in 2017. The measurements were taken using a PMM 8053 EMF meter. In order to determine the change in E levels within a day, a 24 hour long measurement was conducted at the location where the highest average electric field strength (Eavg) was recorded. Results: The evaluation of E measurement results showed that the highest maximum electric field strength (Emax) was 4.75 V/m, and Eavg was 3.35 V/m. The differences between all Emax and Eavg values recorded in the three districts were statistically significant at a 95% confidence level. Emaxs recorded in Ilkadim district showed larger variability than the other districts. It was determined that at only 2% of the 152 measurement locations, Eavg levels were between 2V/m and 4V/m. The assessment of the 24 hour E measurements demonstrated that the highest E value was recorded between 12:00 and 17:59; when the base station was the most active. Furthermore, the mean E value measured during noon hours was 58% higher than the value measured during night hours. Conclusions: Although the recorded E levels were below the limits determined by the ICNIRP and ICTA; it can be considered as high for countries like Switzerland and Italy where lower limits are enforced. Therefore, regular monitoring of E level exposure and keeping E levels within safe limits is recommended in order to protect public health.

The strength and spread of the electric field induced by transcranial rotating permanent magnet stimulation in comparison with conventional transcranial magnetic stimulation

BackgroundWeak or low intensity transcranial stimulation of the brain, such as low field magnetic stimulation and electrical stimulation, can produce significant functional and therapeutic neuromodulatory effects. New methodWe have recently developed a portable wearable multifocal brain stimulator called transcranial rotating permanent magnet stimulator (TRPMS) that uses rapidly spinning high field strength permanent magnets attached to a cap. It produces oscillatory stimuli of different frequencies and patterns. Here we compared the strengths and spatial profiles of the changing magnetic fields of a figure-of-eight transcranial magnetic stimulator (TMS) coil, a TRPMS prototype, and a scaled-up version of TRPMS. We measured field strengths and directions of voltages induced in a magnetic field sensor oriented along all three orthogonal axes. Results and comparison with existing methodsThe spatial spread of the TRPMS-induced electric field is more restricted, and its shape and strength vary less with the orientation of the inductance than TMS. The maximum voltage induced by the current prototype is ∼7% of the maximal TMS output at depths corresponding to the human cerebral cortex from the scalp surface. This field strength can be scaled up by a factor ∼8 with a larger diametrically magnetized magnet. These comparative data allow us to estimate that intracortical effects of TRPMS could be stronger than other low intensity stimulation methods. ConclusionsTRPMS might enable greater uniformity, consistency and focality in stimulation of targeted cortical areas subject to significant anatomical variability. Multiple TRPMS microstimulators can also be combined to produce patterned multifocal spatiotemporal stimulation.

Electromagnetic fields exposure assessment among workers at broadcast centers in Poland.

In the studies investigating the potential health effects of occupational exposure to electromagnetic fields (EMF), the key problem is the assessment of workers' exposure. Electromagnetic fields exposure assessment requires determining maximum EMF levels, for the acute effect, and the dose absorbed, for the cumulative effect. A study was undertaken to determine EMF exposure in workers at broadcasting centers (BCs) in Poland. It was the first part of a comprehensive project on health effects of occupational exposure to EMF. The study was conducted in 4 selected BCs. Spot measurements of electric field strength (E), and the results of E measurements that were made in the past for occupational hygiene assessments, were used for determining workers' exposure to electric field. The parameters considered were the maximum E value (Emax), the weighted average E value (Eavg) and the E lifetime dose (Elifetime dose). In the group of workers examined, the E values did not exceed 16.7 V/m for Emax (the occupational exposure limit (OEL) for work shift in Poland is 20 V/m), 2.9 V/m for Eavg and 1 500 000 (V/m)2×h for Elifetime dose. In view of the lack of dosimetry data, a retrospective assessment of BC workers' exposure to very high frequency and ultra-high frequency EMF was conducted, which made it possible to estimate EMF lifetime dose for the workers. Since the EMF exposure levels at BCs did not exceed the admissible values, they can be considered safe to the workers' health, according to the approach used for developing OELs for EMF exposure. Med Pr 2018;69(5):477-482.

Steel fiber confined graphite concrete for pavement deicing

Electric heating concrete is a specialized concrete containing electrically conductive components to attain stable conduction of electricity. Due to its electrical resistance, a thin electric heating concrete overlay can generate heat to prevent ice formation on a concrete roadway when connected to a power source.This electric heating concrete (EHC) deicing technology has been implemented in China at a large scale for the first time. Steel fibers and graphites had been used at conductive fillers in fabricating EHC. A 3.5-in. (9 cm) thick electric heating concrete layer was cast on the top of two existing parking ramps in Harbin. The East Ramp is 135 feet (41 m) long and 18.5 feet (5.6 m) wide and the North Ramp is 135 feet (41 m) long and 25 feet (7.6 m) wide, both having a steep slope of 15%. The overlay on each parking ramp was divided into 20 blocks.The electric heating concrete overlays were cast in place. Transformers converting 220 V AC to 48 V AC were used for the power source. Steel angle structural shapes were embedded in the electric heating concrete for electrodes. Some electric wires were pulled off from the electrodes during the construction. As a result, the power to a few blocks on each ramp was cut. A hand-held magnetic field meter was used to troubleshoot the disconnection locations. Based on measurements of the magnetic field strengths, all the disconnected wires in the hardened concrete were detected and reattached to the electrodes. The drilled holes were patched with carbon cement paste. Subsequent testing showed that good heating performance was successfully restored.

Theoretical and Experimental Investigation of the Magnetic Field of a Strongly Magnetized Permanent Magnet

An analytical expression is obtained for the magnetic strength of a permanent magnet in the form of a rectangular parallelepiped uniformly magnetized at an angle to its lateral faces. The results from experimental measurements of the magnetic field strength of a permanent magnet in the form of a rectangular parallelepiped using a Hall sensor are presented and compared to those from analytical calculations.

Radially scanning magnetic probes to study local helicity injection dynamics.

Two new magnetic probes have been deployed on the Pegasus spherical tokamak to study the dynamics of local helicity injection non-solenoidal plasma start-up and current drive. The magnetic radial array probe consists of 15 pickup coils (∼5 × 8 mm each) that measure over a 15 cm linear extent. The coils consist of traces embedded in a printed circuit board. Three coil designs are utilized to balance frequency response and coil sensitivity. Helmholtz coil measurements are used to measure coil and full assembly bandwidths (∼2 MHz and ∼200 kHz, respectively) and sensitivities (0.18/0.35/0.96 mV T-1 s). The magnetic radial scanning probe is an array of Hall effect sensors that measure field strength ( mT) and direction at 8 spatial points (ΔR = 1.5 cm), supporting the studies of equilibrium field structure and low-frequency (≤5 kHz) current dynamics. It uses commercial surface-mount Hall effect sensors with chip-integrated amplifiers and compensators that are mounted in a 3-D printed frame. Helmholtz coil measurements indicate negligible cross-field gain nonlinearity and provide absolute calibration of the diagnostic. Both probes are constructed as an electrostatically shielded insertable air-side assembly that mounts within a radially translatable ultrahigh vacuum assembly from an existing probe.

Direct Tracking of Ultrafast Carrier Motion Dynamics in Semiconducting Single-Wall Carbon Nanotubes

An Ultrafast all-optical electric field strength measurement technique based on the electric-field-induced second harmonic generation together with conventional transient photocurrent measurements has been applied for the direct tracking of carrier separation and motion dynamics in semiconducting single-wall carbon nanotubes (SWNTs). Thin films of (6,5)-SWNT-enriched samples were prepared on combs of interdigitated electrodes with different concentrations of fullerene derivative phenyl-C61-butyric acid methyl ester (PCBM) serving as an electron acceptor. Neutral delocalized excitons photogenerated in the samples with high PCBM concentration were found to form localized charge-transfer (CT) states within less than 1 ps with the electron transferred to the PCBM and a hole remaining on the SWNT. The hole’s drift along the length of individual nanotubes was found to take ∼200–1000 ps and is most likely limited by dissociation of the CT states rather than by the hole’s mobility. A fraction of about (30–50)% of generated charge carriers was found to recombine within 3.6 ns measurement interval.

Spatially Resolved Measurements of Metastable Atom Density and Electric Field Strength in a Microhollow Cathode Helium Plasma by Laser Absorption Spectroscopy

Spatially Resolved Measurements of Metastable Atom Density and Electric Field Strength in a Microhollow Cathode Helium Plasma by Laser Absorption Spectroscopy

The Magnetic Binary GJ 65: A Test of Magnetic Diffusivity Effects

Abstract GJ 65 is an M dwarf binary system consisting of the two flare stars BL Cet (GJ 65A) and UV Cet (GJ 65B). Two teams of investigators have recently reported total magnetic fluxes corresponding to fields of 4.5 and 5.2 kG for GJ 65A and 5.8 and 6.7 kG for GJ 65B: for each component, the magnetic results obtained by the two teams agree with each other to within 1σ. For the first time, we can directly compare the predictions of our magneto-convective models, based on fitting observed stellar parameters, with measured field strengths. We find that our models agree with the observed field strengths, provided the effects of finite conductivity are accounted for. Thus, GJ 65 provides us with an opportunity to use observations of field strengths to distinguish between the predictions of our models that assume perfect electrical conductivity and those that allow for finite conductivity.

Electromagnetically Induced Transparency (EIT) and Autler-Townes (AT) splitting in the presence of band-limited white Gaussian noise

We investigate the effect of band-limited white Gaussian noise (BLWGN) on electromagnetically induced transparency (EIT) and Autler-Townes (AT) splitting, when performing atom-based continuous-wave (CW) radio-frequency (RF) electric (E) field strength measurements with Rydberg atoms in an atomic vapor. This EIT/AT-based E-field measurement approach is currently being investigated by several groups around the world as a means to develop a new International System of Units traceable RF E-field measurement technique. For this to be a useful technique, it is important to understand the influence of BLWGN. We perform EIT/AT based E-field experiments with BLWGN centered on the RF transition frequency and for the BLWGN blue-shifted and red-shifted relative to the RF transition frequency. The EIT signal can be severely distorted for certain noise conditions (bandwidth, center frequency, and noise power), hence altering the ability to accurately measure a CW RF E-field strength. We present a model to predict the line shifts and broadenings in the EIT signal in the presence of noise. This model includes AC Stark shifts and on resonance transitions associated with the noise source. The results of this model are compared to the experimental data, and we find very good agreement between the two.

Measurement and Analysis of Electromagnetic Field Strength in Port Harcourt and its Environs Due to Treasure FM Radio Transmitter

This paper Presents the measurement of electromagnetic field strength of Treasure FM transmitter operating at a frequency of 98.5MHz in Port Harcourt and its environs with the aid of an Automated Band Scanner GPS system. The measurement were carried out by taking the radio Station’s transmitter as a reference point at the Centre and selecting 24 measuring points around the transmitter. These points were selected with 1km spacing taken as the interval between two measuring points, summing up to a total of 6km due North, East, West and South of the Radio Transmitter respectively. The result obtained was critically analyzed and interpreted with the aid of an attenuation decay curve. The behavior of the signal was seen to be a function of the Ground Constant of the terrain, reflection of the signal from the earth surface, Diffraction by obstacles and transmitter parameters such as transmitter Power, Antenna Gain and Antenna Height.