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As for the direct-current (DC) power systems, the DC leakage current sensor is indispensable for positioning insulation faults. And in this paper, a quasi-digital flux gate sensor was designed based on duty ratio model, and the mathematical model between the excitation voltage period and the measured current which exceeded the measurement range was built by analyzing the working principles of the duty-ratio model digital sensor. In this way, the measurement range of the original sensor could be expanded to 1.5 times of its original. Meanwhile, without changing the hardware, the solution provided in this paper also solved the measurement failure problem of part of sensors when the any overcurrent situations happen in the system, such as overload or short-circuit. Besides, the sensor designed in this paper could achieve Level-0.1 measurement accuracy within range, and reach Level-2 over-range measurement accuracy, satisfying the demands of DC power supply system on leakage current measurement.

The mass-balance—elevation relation for a given glacier is required for many numerical models of ice flow. Direct measurements of this relation using remotely-sensed methods are complicated by ice dynamics, so observations are currently limited to glaciers where surface mass-balance measurements are routinely made. We test the viability of using the continuity equation to estimate annual surface mass balance between flux-gates in the absence of in situ measurements, on five glaciers in the Columbia Mountains of British Columbia, Canada. Repeat airborne laser scanning surveys of glacier surface elevation, ice penetrating radar surveys and publicly available maps of ice thickness are used to estimate changes in surface elevation and ice flux. We evaluate this approach by comparing modeled to observed mass balance. Modeled mass-balance gradients well-approximate those obtained from direct measurement of surface mass balance, with a mean difference of +6.6 ± 4%. Regressing modeled mass balance, equilibrium line altitudes are on average 15 m higher than satellite-observations of the transient snow line. Estimates of mass balance over flux bins compare less favorably than the gradients. Average mean error (+0.03 ± 0.07 m w.e.) between observed and modeled mass balance over flux bins is relatively small, yet mean absolute error (0.55 ± 0.18 m w.e.) and average modeled mass-balance uncertainty (0.57 m w.e.) are large. Mass conservation, assessed with glaciological data, is respected (when estimates are within 1σ uncertainties) for 84% of flux bins representing 86% of total glacier area. Uncertainty on ice velocity, especially for areas where surface velocity is low (

The flux gate for measurement of size and direction of magnetic field of the Earth and for measurement of local magnetic fields, applying the unidirectional pulse scheme in an excitement chain are examined. The article treats the benefits of ferroprobes with pulse excitement in comparison with the similar sensors with sinusoidal excitement. According to the original circuit proposed by the authors of the article flux gate sensor for measurement of a local magnetic field with two ferroprobes for the purpose of compensation of the Earth’s magnetic field is designed. The experiment with flux gate sensors which contain various quantities of rounds in an output winding and a permanent magnet is carried out. The factors that influence the output voltage of the sensor are examined during the experiment. The regression equation for the ferroprobe by the experimental data is obtained. The regression is important for development of similar measuring systems. First of all, the results of the research are important for the analysis of technical characteristics of magneto-modulation sensors, and for ferroprobes design in aircraft industry.

Results of geodetic in-situ observations of ice-flow velocities in the southern part of subglacialLakeVostokare combined with data sets of the ice surface topography, ice thickness, surface accumulation, basal accretion and firn/ice density for interpretations regarding the glaciological setting of theLakeVostoksystem. Based on the ice-flow velocities and the ice thickness, mean surface accumulation rates are derived applying the flux gate method. These are representative for surface segments extending from the southern part ofLakeVostokto the Ridge B ice divide. They are consistent with the present-day accumulation rate at Vostok station and its variation upstream and thus suggest that the area has been close to steady state. In addition, ice-flow dynamics are investigated along a flow line segment extending from26 kmupstream to12 kmdownstream from Vostok station. The analysis suggests deficiencies in current modelling approaches within the transition zone from floating to grounded ice.

The distorting effect of a ferromagnetic disk of finite dimensions on the constant field of a magnetic dipole is considered. It is shown that, depending on the mutual arrangement of the dipole and disk, the dipole field may be both intensified and attenuated. It was proposed for the first time to use an additional ferromagnetic disk in order to attenuate the shielding effect of a ferromagnetic disk on a dipole field. The theoretical considerations were confirmed by the experimental results. The presented information can be useful when organizing testing of the magnetic fields of objects that are placed behind a ferromagnetic obstacle. [ABSTRACT FROM AUTHOR]

The current deficit in Greenland ice sheet mass balance is due to both a decrease in surface mass balance ( SMB ) input and an increase in ice discharge ( D ) output. While SMB processes are beginning to be well captured by observationally-constrained climate modeling, insight into D is relatively limited. We use InSAR-derived velocities, in combination with ice thickness observations, to quantify the mass flux ( F ) across a flux perimeter around the ice sheet at ∼1700 m elevation. To quantify D , we correct F for SMB , as well as changes in volume due to ice dynamics, in the area downstream of the gate. Using a 1961–1990 reference climatology SMB field from the MAR regional climate model, we quantify ice sheet mass balance within eighteen basins. We find a 2007–2011 mean D of 515 ± 57 Gt yr − 1 . We find a 2007–2011 mean total mass balance of − 262 ± 21 Gt yr − 1 , which is equal to a 0.73 mm yr −1 global sea level rise contribution. This mass loss is dominated by SMB , which accounts for 61% of mass loss in the basins where partitioning is possible. [ABSTRACT FROM AUTHOR]

Magnetic field transducers that vary in their suitability for use in contemporary magnetic nondestructive testing are considered. The experimental data on the resolution of some transducer types are presented. [ABSTRACT FROM AUTHOR]

The development of a control device of ship hull mechanical stresses during cargo and ballast operations based on a magnetometric method is proposed in the paper. The proposed method provides controlling mechanical stresses in real time, unambiguously connects elastic stresses with a controlled variable, i.e. a retentive magnetism. Herewith, the device, carrying out this method, is constructed on the basis of flux gates, making it simple and reliable in operation. The estimation of metrological characteristics of the device elements controlling mechanical stresses of a ship hull was made. For this purpose, an experimental study of constituent elements of the device was conducted. For compensating the Earth magnetic field, it was suggested using an additional magnetometric channel. The obtained research results allow developing and manufacturing a commercial prototype of a fluxgate continuous monitoring device of ship hull mechanical stresses. [ABSTRACT FROM AUTHOR]

Abstract: In this work an electromagnetic non-invasive and contact-less technique using Flux-Gate first-order gradiometer is proposed to detect the magnetic field distribution during electropolishing of copper surface. The electropolishing of the copper surface employed in superconducting RF TESLA-type cavities has been monitored using magnetic field sensors. Local information regarding the dissolved copper surface during the electropolishing process has been obtained. An electromagnetic inversion of the magnetic field imaging have been implemented to better understand the effect of the cathode geometry on the electropolishing process. [Copyright &y& Elsevier]