Appraisal of electromagnetic induction effects on magnetic pulsation studies

Abstract. The quantification of wave polarization characteristics of ULF waves from the geomagnetic field variations is done under ‘a priori’ assumption that fields of internal induced currents are in-phase with the external inducing fields. Such approximation is invalidated in the regions marked by large lateral conductivity variations that perturb the flow pattern of induced currents. The amplitude and phase changes that these perturbations produce, in the resultant fields at the Earth’s surface, make determination of polarization and phase of the oscillating external signals problematic. In this paper, with the help of a classical Pc5 magnetic pulsation event of 24 March 1991, recorded by dense network of magnetometers in the equatorial belt of Brazil, we document the nature and extent of the possible influence of anomalous induction effects in the wave polarization of ULF waves. The presence of anomalous induction effects at selected sites lead to an over estimation of the equatorial enhancement at pulsation period and also suggest changes in the azimuth of ULF waves as they propagate through the equatorial electrojet. Through numerical calculations, it is shown that anomalous horizontal fields, that result from induction in the lateral conductivity distribution in the study region, vary in magnitude and phase with the polarization of external source field. Essentially, the induction response is also a function of the period of external inducing source field. It is further shown that when anomalous induction fields corresponding to the magnitude and polarization of the 24 March 1991 pulsation event are eliminated from observed fields, corrected amplitude in the X and Y horizontal components allows for true characterisation of ULF wave parameters.Key words. Geomagnetism and paleomagnetism (geomagnetic induction) – Ionosphere (equatorial ionosphere) – Magnetospheric physics (magnetosphere-ionosphere interactions)

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Pc5 waves generated by substorm injection: a case study

Annales Geophysicae ◽

10.5194/angeo-26-2053-2008 ◽

2008 ◽

Vol 26 (7) ◽

pp. 2053-2059 ◽

Cited By ~ 26

Author(s):

N. A. Zolotukhina ◽

P. N. Mager ◽

D. Yu. Klimushkin

Keyword(s):

Electron Cloud ◽

Substorm Onset ◽

Ulf Waves ◽

Wave Polarization ◽

Substorm Injection ◽

Ion Cloud ◽

The Waves ◽

Positive Ion ◽

Onset Location

Abstract. We analyzed the spectral-polarized characteristics of Pc5 ULF waves observed on 17 September 2000 after the 03:20:25 UT substorm onset with the satellites GOES 8 and 10 located east and west of the onset location. In the course of the event, the wave polarization changed from mixed (between toroidal and poloidal) to poloidal, and then to mixed again. The hodogram of magnetic field oscillations rotated counterclockwise at GOES 8, and clockwise at GOES 10. It is suggested that the satellites detected the waves generated by the substorm injected clouds of the charged particles drifting in the magnetosphere in the opposite azimuthal directions: GOES 8 (located east of the substorm onset) detected the wave generated by an electron cloud, and GOES 10 (west of the onset) detected the wave generated by a positive ion cloud. This interpretation is confirmed by the energetic particles data recorded by LANL satellites.

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The Perturbation of Slowly Varying Electromagnetic Fields by Three-Dimensional Conducting Bodies

Canadian Journal of Physics ◽

10.1139/p74-161 ◽

1974 ◽

Vol 52 (13) ◽

pp. 1195-1202 ◽

Cited By ~ 8

Author(s):

F. W. Jones

Keyword(s):

Numerical Method ◽

Electromagnetic Fields ◽

Three Dimensional ◽

Two Dimensional ◽

Source Field ◽

Induced Currents ◽

Dimensional Models ◽

Conducting Bodies

The perturbation of a slowly varying alternating field by conducting bodies of cubic shape is considered. A numerical method is used to determine the fields associated with the induced currents. Current concentrations are produced in the corners of the conductors, and these move inward and decay with time as the source field varies. A cavity region within the conductor further distorts the fields. A comparison is made with two-dimensional models.

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Stormtime Equatorial Electrojet Ground-Induced Currents

Ionospheric Space Weather - Geophysical Monograph Series ◽

10.1002/9781118929216.ch3 ◽

2016 ◽

pp. 33-40 ◽

Cited By ~ 3

Author(s):

Mark B. Moldwin ◽

Justin S. Tsu

Keyword(s):

Equatorial Electrojet ◽

Induced Currents

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The Interpretation of Crystal Lattice Images

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010009600x ◽

1972 ◽

Vol 30 ◽

pp. 550-551

Author(s):

J. M. Cowley ◽

Sumio Iijima

Keyword(s):

Crystal Orientation ◽

Diffraction Theory ◽

Phase Changes ◽

Electron Wave ◽

Crystal Lattices ◽

Heavy Atoms ◽

Lattice Images ◽

The Right ◽

Intuitive Interpretation ◽

Suitable Approximation

The imaging of detailed structures of crystal lattices with 3 to 4Å resolution, given the correct conditions of microscope defocus and crystal orientation and thickness, has been used by Iijima (this conference) for the study of new types of crystal structures and the defects in known structures associated with fluctuations of stoichiometry. The image intensities may be computed using n-beam dynamical diffraction theory involving several hundred beams (Fejes, this conference). However it is still important to have a suitable approximation to provide an immediate rough estimate of contrast and an evaluation of the intuitive interpretation in terms of an amplitude object.For crystals 100 to 150Å thick containing moderately heavy atoms the phase changes of the electron wave vary by about 10 radians suggesting that the “optimum defocus” theory of amplitude contrast for thin phase objects due to Scherzer and others can not apply, although it does predict the right defocus for optimum imaging.

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Influence of trees on the energy consumption of a social housing in mid-western Brazil

WEENTECH Proceedings in Energy ◽

10.32438/wpe.4819 ◽

2019 ◽

pp. 53-65

Author(s):

Renata Domingos ◽

Emeli Guarda ◽

Elaise Gabriel ◽

João Sanches

Keyword(s):

Energy Consumption ◽

Solar Radiation ◽

Thermal Comfort ◽

Air Conditioning ◽

Computational Simulation ◽

Building Energy ◽

General Idea ◽

Heat Island ◽

Study Region ◽

Ample Evidence

In the last decades, many studies have shown ample evidence that the existence of trees and vegetation around buildings can contribute to reduce the demand for energy by cooling and heating. The use of green areas in the urban environment as an effective strategy in reducing the cooling load of buildings has attracted much attention, though there is a lack of quantitative actions to apply the general idea to a specific building or location. Due to the large-scale construction of high buildings, large amounts of solar radiation are reflected and stored in the canyons of the streets. This causes higher air temperature and surface temperature in city areas compared to the rural environment and, consequently, deteriorates the urban heat island effect. The constant high temperatures lead to more air conditioning demand time, which results in a significant increase in building energy consumption. In general, the shade of the trees reduces the building energy demand for air conditioning, reducing solar radiation on the walls and roofs. The increase of urban green spaces has been extensively accepted as effective in mitigating the effects of heat island and reducing energy use in buildings. However, by influencing temperatures, especially extreme, it is likely that trees also affect human health, an important economic variable of interest. Since human behavior has a major influence on maintaining environmental quality, today's urban problems such as air and water pollution, floods, excessive noise, cause serious damage to the physical and mental health of the population. By minimizing these problems, vegetation (especially trees) is generally known to provide a range of ecosystem services such as rainwater reduction, air pollution mitigation, noise reduction, etc. This study focuses on the functions of temperature regulation, improvement of external thermal comfort and cooling energy reduction, so it aims to evaluate the influence of trees on the energy consumption of a house in the mid-western Brazil, located at latitude 15 ° S, in the center of South America. The methodology adopted was computer simulation, analyzing two scenarios that deal with issues such as the influence of vegetation and tree shade on the energy consumption of a building. In this way, the methodological procedures were divided into three stages: climatic contextualization of the study region; definition of a basic dwelling, of the thermophysical properties; computational simulation for quantification of energy consumption for the four facade orientations. The results show that the façades orientated to north, east and south, without the insertion of arboreal shading, obtained higher values of annual energy consumption. With the adoption of shading, the facades obtained a consumption reduction of around 7,4%. It is concluded that shading vegetation can bring significant climatic contribution to the interior of built environments and, consequently, reduction in energy consumption, promoting improvements in the thermal comfort conditions of users.

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Remote diagnostics of vibrations of dynamic objects by Doppler microwave sensors

Metrologiya ◽

10.32446/0132-4713.2020-3-25-42 ◽

2020 ◽

pp. 25-42

Author(s):

Dmitrii V. Khablov

Keyword(s):

Intelligent Systems ◽

Electromagnetic Waves ◽

Continuous Monitoring ◽

Phase Changes ◽

Vibration Diagnostics ◽

Remote Diagnostics ◽

Active Vibration ◽

Dynamic Objects ◽

Microwave Sensors ◽

Non Destructive

This paper describes a promising method for non-contact vibration diagnostics based on the use of Doppler microwave sensors. In this case, active irradiation of the object with electromagnetic waves and the allocation of phase changes using two-channel quadrature processing of the received reflected signal are used. The modes of further fine analysis of the resulting signal using spectral or wavelet transformations depending on the nature of the active vibration are considered. The advantages of this non-contact and remote vibration analysis method for the study of complex dynamic objects are described. The convenience of the method for machine learning and use in intelligent systems of non-destructive continuous monitoring of the state of these objects by vibration is noted.

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