scholarly journals The development of the INGV tectonomagnetic network in the frame of the MEM Project

2007 ◽  
Vol 7 (4) ◽  
pp. 473-478 ◽  
Author(s):  
F. Masci ◽  
P. Palangio ◽  
M. Di Persio ◽  
C. Di Lorenzo
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Transfer Functions ◽  
Central Italy ◽  
Local Magnetic Field ◽  
Actual State ◽  
Data Set ◽  
New Approach ◽  
Time Variations ◽  
Relationship Of

Abstract. In the middle of 1989, the INGV (Italian Istituto Nazionale di Geofisica e Vulcanologia) installed in Central Italy a network of magnetic stations in order to investigate possible relationship of the local magnetic field with earthquakes occurrences. Actually the network consists of four stations, where the total magnetic field intensity data are being collected using proton precession magnetometers. Here we are report on the actual state and the future developments of the network. In the frame of the MEM (Magnetic and Electric fields Monitoring) Project, new stations will be added to the network by the end of 2007. The results of the test campaigns carried out in the sites chosen to widen the network are also discussed. Moreover, the 2006 complete data set of the network is also reported. Concerning the data analysis, a new approach is also discussed that takes into account the inductive effects on the local geomagnetic field by means of the inter-station transfer functions time variations analysis.

scholarly journals Magnetic field configuration and field-aligned acceleration of energetic ions during substorm onsets

2001 ◽  
Vol 19 (9) ◽  
pp. 1089-1094 ◽  
Author(s):  
A. Korth ◽  
Z. Y. Pu
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Plasma Sheet ◽  
Field Configuration ◽  
Local Magnetic Field ◽  
Magnetospheric Configuration And Dynamics ◽  
Night Side ◽  
Field Lines ◽  
Synchronous Orbit ◽  
Substorm Onsets

Abstract. In this paper, we present an interpretation of the observed field-aligned acceleration events measured by GEOS-2 near the night-side synchronous orbit at substorm onsets (Chen et al., 2000). We show that field-aligned acceleration of ions (with pitch angle asymmetry) is closely related to strong short-lived electric fields in the Ey direction. The acceleration is associated with either rapid dipolarization or further stretching of local magnetic field lines. Theoretical analysis suggests that a centrifugal mechanism is a likely candidate for the parallel energization. Equatorward or anti-equatorward energization occurs when the tail current sheet is thinner tailward or earthward of the spacecraft, respectively. The magnetic field topology leading to anti-equatorward energization corresponds to a situation where the near-Earth tail undergoes further compression and the inner edge of the plasma sheet extends inwards as close as the night-side geosynchronous altitudes.Key words. Magnetospheric physics (magnetospheric configuration and dynamics; plasma sheet; storms and sub-storms)

Electric fields and local magnetic field enhance Ag-BiVO4-MnOx photoelectrochemical and photocatalytic performance

2020 ◽  
Vol 511 ◽  
pp. 145534 ◽  
Author(s):  
Bin Li ◽  
Guoqiang Tan ◽  
Min Wang ◽  
Dan Zhang ◽  
Minyue Dang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Photocatalytic Performance ◽  
Local Magnetic Field

Seismoelectric wave conversions in porous media: Field measurements and transfer function analysis

Geophysics ◽  
2001 ◽  
Vol 66 (5) ◽  
pp. 1417-1430 ◽  
Author(s):  
Stéphane Garambois ◽  
Michel Dietrich
Keyword(s):  
Magnetic Field ◽  
Dielectric Constant ◽  
Electric Field ◽  
Electric Fields ◽  
Field Experiments ◽  
Transfer Functions ◽  
Function Analysis ◽  
Transfer Function Analysis ◽  
Electromagnetic Disturbances ◽  
The Magnetic Field

We present a series of field experiments showing the transient electric fields generated by a seismic excitation of the subsurface. After removing the powerline noise by adaptive filtering, the most prominent feature of the seismoelectric recordings is the presence of electric signals very similar to conventional seismic recordings. In one instance, we identified small‐amplitude precursory electromagnetic disturbances showing a polarity reversal on either side of the shotpoint. Concentrating on the dominant seismoelectric effect, we theoretically show that the electric field accompanying the compressional waves is approximately proportional to the grain acceleration. We also demonstrate that the magnetic field moving along with shear waves is roughly proportional to the grain velocity. These relationships hold true as long as the displacement currents are much smaller than the conduction currents (diffusive regime), which is normally the case in the low‐frequency range used in seismic prospecting. Furthermore, the analytical transfer functions thus obtained indicate that the electric field is mainly sensitive to the salt concentration and dielectric constant of the fluid, whereas the magnetic field principally depends on the shear modulus of the framework of grains and on the fluid’s viscosity and dielectric constant. Both transfer functions are essentially independent of the permeability. Our results suggest that the simultaneous recording of seismic, electric, and magnetic wavefields can be useful for characterizing porous layers at two different levels of investigation: near the receivers and at greater depth.

scholarly journals The Electron Drift Instrument on Cluster: overview of first results

2001 ◽  
Vol 19 (10/12) ◽  
pp. 1273-1288 ◽  
Author(s):  
G. Paschmann ◽  
J. M. Quinn ◽  
R. B. Torbert ◽  
H. Vaith ◽  
C. E. McIlwain ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Drift Velocity ◽  
Electron Beams ◽  
Local Magnetic Field ◽  
Electron Drift ◽  
Plasma Convection ◽  
Wide Range ◽  
First Results ◽  
The Difference

Abstract. EDI measures the drift velocity of artificially injected electron beams. From this drift velocity, the perpendicular electric field and the local magnetic field gradients can be deduced when employing different electron energies. The technique requires the injection of two electron beams at right angles to the magnetic field and the search for those directions within the plane that return the beams to their associated detectors after one or more gyrations. The drift velocity is then derived from the directions of the two beams and/or from the difference in their times-of-flight, measured via amplitude-modulation and coding of the emitted electron beams and correlation with the signal from the returning electrons. After careful adjustment of the control parameters, the beam recognition algorithms, and the onboard magnetometer calibrations during the commissioning phase, EDI is providing excellent data over a wide range of conditions. In this paper, we present first results in a variety of regions ranging from the polar cap, across the magnetopause, and well into the magnetosheath.Key words. Electron drift velocity (electric fields; plasma convection; instruments and techniques)

scholarly journals Particle Acceleration and Nonthermal Energy Release as an Effect of Magnetoactive Disk Accretion Onto Gravitating Center

1994 ◽  
Vol 142 ◽  
pp. 959-961
Author(s):  
N. R. Ikhsanov ◽  
L. A. Pustil’nik
Keyword(s):  
Magnetic Field ◽  
Particle Acceleration ◽  
Energy Release ◽  
Electric Fields ◽  
Double Layers ◽  
Disk Accretion ◽  
New Approach ◽  
Effective Particle ◽  
Z Pinch ◽  
The Magnetic Field

AbstractObservations of GRO and UHEGR show that a number of Galactic and extragalactic accreting systems release most of their energy in the ultrarelativistic energy range (more than GeV). This result contradicts one of the principal conclusions of the standard models of accretion about a predominantly thermal character of energy release. This contradiction is caused by ignoring in the standard approach the processes of generation and amplification of magnetic field in the case of accretion onto a magnetized gravitating center. A new approach taking into account the processes mentioned above is applied to disk accretion onto a nonmagnetized gravitating center, as well as onto a magnetosphere. It is shown that in both cases the accretion is strictly controlled by the magnetic field, which leads to new conditions of equilibrium and stability and turns on nonthermal processes of energy release. The resulting configuration of the magnetic field, in which the main energy release takes place in both cases, is called “Z-pinch,” and is formed in the polar region of an accreting object. Effective particle acceleration occurs in it owing to the chain of MHD and resistive plasma instabilities, resulting in current discontinuity with the formation of “double layers” and generation of electric fields close to the Dreicer limit in them. The maximum energies of the accelerated particles are limited by the value 10 EeV, that coincides with the results of UHEGR observations.Subject headings: acceleration of particles — accretion, accretion disks — gamma rays: theory — MHD

A New Approach to Flat Form Error and Contact Error Analysis

2013 ◽  
Vol 300-301 ◽  
pp. 676-680
Author(s):  
Qin Liu ◽  
Wei Ren Wu ◽  
Zhi Jing Zhang ◽  
Xin Jin
Keyword(s):  
Cross Section ◽  
Three Dimensional ◽  
Radius Of Curvature ◽  
Form Error ◽  
Profile Error ◽  
Data Set ◽  
New Approach ◽  
Multi Scale ◽  
Flat Profile ◽  
Relationship Of

A new model based on multi-scale asperities is established in order to accurately describe flat profile error. After measuring the surface, surface points are projected to each cross-section according to three-dimensional coordinates. Graham’s Scan algorithm is used to search border points of each data set. Then minimum circum-circle is calculated and optimized. Asperity’s radius of curvature and coordinates is calculated by relationship of circle radius and section’s interval. In the assembly process, it is primarily that the peaks on surface actually contact. The contact error plane equation is determined by three asperities which can stability support the other part, so three proper asperities should be searched out firstly. Finally, experimental results show that this model can be applied to calculated contact error.

scholarly journals The INGV tectonomagnetic network

2008 ◽  
Vol 14 ◽  
pp. 65-68 ◽  
Author(s):  
F. Masci ◽  
P. Palangio ◽  
M. Di Persio
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Magnetic Field Intensity ◽  
Central Italy ◽  
Magnetic Anomalies ◽  
Data Sets ◽  
Intensity Data ◽  
Geomagnetic Observatory ◽  
Data Set ◽  
Latitude Range

Abstract. The Italian Istituto Nazionale di Geofisica e Vulcanologia (INGV) tectonomagnetic network was installed in Central Italy since the middle of 1989 to investigate possible magnetic anomalies related to earthquakes. The network is part of the INGV L'Aquila Geomagnetic Observatory and is located in an area extending approximately in latitude range [41.6°–42.8°] N and longitude range [13.0°–14.3°] E. Actually the network consists of four stations where the total magnetic field intensity data are collected using proton precession magnetometers. New stations will be added to the network starting from the end of 2007. Here we are reporting the whole data set of the network's stations for the period 2004–2006. No significant anomaly in the local geomagnetic field correlated to the seismic activity has been found. Some considerations about misleading structures present in the data sets are reported.

Colonialism and the Highland Clearances

2017 ◽  
Vol 8 (1) ◽  
pp. 22-48 ◽  
Author(s):  
Iain Mackinnon
Keyword(s):  
Industrial Development ◽  
Comparative Approach ◽  
Indigenous Research ◽  
Internal Colonialism ◽  
New Approach ◽  
A Site ◽  
Relationship Of ◽  
The Relationship ◽  
Imperial State ◽  
Late Modern

This article employs a new approach to studying internal colonialism in northern Scotland during the 18th and 19th centuries. A common approach to examining internal colonial situations within modern state territories is to compare characteristics of the internal colonial situation with attested attributes of external colonial relations. Although this article does not reject the comparative approach, it seeks to avoid criticisms that this approach can be misleading by demonstrating that promoters and managers of projects involving land use change, territorial dispossession and industrial development in the late modern Gàidhealtachd consistently conceived of their work as projects of colonization. It further argues that the new social, cultural and political structures these projects imposed on the area's indigenous population correspond to those found in other colonial situations, and that racist and racialist attitudes towards Gaels of the time are typical of those in colonial situations during the period. The article concludes that the late modern Gàidhealtachd has been a site of internal colonization where the relationship of domination between colonizer and colonized is complex, longstanding and occurring within the imperial state. In doing so it demonstrates that the history and present of the Gaels of Scotland belongs within the ambit of an emerging indigenous research paradigm.

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