scholarly journals Magnetic signatures of equatorial spreadFas observed by the CHAMP satellite

2006 ◽  
Vol 111 (A2) ◽  
Author(s):  
C. Stolle ◽  
H. Lühr ◽  
M. Rother ◽  
G. Balasis
Keyword(s):  
Champ Satellite ◽  
Magnetic Signatures

scholarly journals Improving and testing the empirical equatorial electrojet model with CHAMP satellite data

2004 ◽  
Vol 22 (9) ◽  
pp. 3323-3333 ◽  
Author(s):  
V. Doumouya ◽  
Y. Cohen
Keyword(s):  
Equatorial Electrojet ◽  
Ground Level ◽  
Longitudinal Variation ◽  
Equatorial Station ◽  
Champ Satellite ◽  
Magnetic Effects ◽  
Level Data ◽  
The Pacific ◽  
Magnetic Signatures ◽  
Data Points

Abstract. The longitudinal variation of the Equatorial Electrojet (EEJ) intensity has been revised including data from the equatorial station of Baclieu (Vietnam), where an unexpected enhancement of the EEJ magnetic effects is observed. The features of this longitudinal variation were also obtained with the CHAMP satellite, except in the Pacific and Atlantic Oceans, where no ground level data points were available.The EEJ magnetic signatures recorded on board the CHAMP satellite have been isolated for 325 passes in different longitude sectors around local noon. The results have been compared with the EEJ magnetic effects computed using the Empirical Equatorial Electrojet Model (3EM) proposed by Doumouya et al. (2003). The modeled EEJ magnetic effects are generally in good agreement with CHAMP observed EEJ magnetic signatures.

scholarly journals Magnetic signatures and conjugate features of low-latitude plasma blobs as observed by the CHAMP satellite

2008 ◽  
Vol 113 (A9) ◽  
pp. n/a-n/a ◽  
Author(s):  
Jaeheung Park ◽  
Claudia Stolle ◽  
Hermann Lühr ◽  
Martin Rother ◽  
Shin-Yi Su ◽  
...  
Keyword(s):  
Low Latitude ◽  
Champ Satellite ◽  
Magnetic Signatures ◽  
Plasma Blobs

NON-DESTRUCTIVE EVALUATION OF MECHANICAL DAMAGE OF ADHESIVES USING MAGNETO-ELECTRIC NANOPARTICLES

2021 ◽  
Author(s):  
GONZALO SEISDEDOS ◽  
BRIAN HERNANDEZ ◽  
JULIETTE DUBON ◽  
MARIANA ONTIVEROS ◽  
BENJAMIN BOESL ◽  
...  
Keyword(s):  
Adhesive Joint ◽  
Adhesive Bonding ◽  
Mechanical Damage ◽  
Adhesive Bond ◽  
Tensile Tests ◽  
Adhesive Joints ◽  
Adhesive Bonds ◽  
Magnetic Signatures ◽  
Looper System ◽  
Lock In

Adhesive bonding has been shown to successfully address some of the main problems with traditional fasteners, such as the reduction of the overall weight and a more uniformly distributed stress state. However, due to the unpredictability of failure of adhesive bonds, their use is not widely accepted in the aerospace industry. Unlike traditional fastening methods, it is difficult to inspect the health of an adhesive joint once it has been cured. For adhesive bonding to be widely accepted and implemented, there must be a better understanding of the fracture mechanism of the adhesive joints, as well as a way to monitor the health of the bonds nondestructively. Therefore, in-field structural health monitoring is an important tool to ensure optimal condition of the bond is present during its lifetime. This project focuses on the advancement of a non-invasive field instrument for evaluation of the health of the adhesive joints. The tool developed is based on a B-H looper system where coils are arranged into a noise-cancellation configuration to measure the magnetic susceptibility of the samples with a lock-in amplifier. The B-H looper system can evaluate the state of damage in an adhesive bond by detecting changes in surface charge density at the molecular level of an epoxy-based adhesive doped with magneto-electric nanoparticles (MENs). Epoxy-based adhesive samples were doped with MENs and then scanned using the B-H looper system. To evaluate the health of the adhesive joint, microindentation and tensile tests were performed on MENs-doped adhesive samples to understand the relationship between mechanical damage and magnetic signal. Correlations between magnetic signatures and mechanical damage were minimally observed, thus future studies will focus on refining the procedure and damaging methodology.

Resolving Optimum Magnetic Signatures for Drill-Hole Targeting in Gold Exploration – A Case Study for Mbudzane in Gwanda, Zimbabwe

2013 ◽  
Vol 3 (1) ◽  
pp. 9-29
Author(s):  
Dumisani John Hlatywayo ◽  
Emmanuel Sakala
Keyword(s):  
Drill Hole ◽  
Magnetic Survey ◽  
Gold Exploration ◽  
Rock Formations ◽  
Induced Polarisation ◽  
Line Spacing ◽  
Magnetic Signatures ◽  
Ground Magnetic ◽  
Tilt Derivative ◽  
Resistivity Image

Optimum magnetic signatures for drill-hole targeting in gold exploration in Mbudzane were resolved from induced polarisation-resistivity and magnetic anomalies. Total magnetic field and a gold-in-soil map showed the area is magnetically quiet with high anomalous values along old gold workings. Induced polarisation was carried out along a grid for lines of 500m length, 50m separation and a baseline oriented at 330˚. The survey comprised a gradient array and three real sections. The magnetic survey was conducted over the same grid as the induced polarisation. Stations were set at 5m intervals for a line spacing of 50m. The results show intense anomalies that suggest different degrees of magnetic alteration and a set of conjugate lineaments and faults that possibly control the mineralisation in Mbudzane. The tilt derivative of the reduced-to-pole image resolves the separation between anomalies, giving information on the faulting. High chargeability is confined to the sheared and silicified mafic schist. The gradient resistivity image revealed contact between rock formations. Real section IP shows coincident low chargeability – low resistivity anomalies close to the surface. Chargeability intensity increases with depth, suggesting incipient development of disseminated sulphide replacement zones. A strong correlation between ground magnetic inferred contacts and apparent resistivity-chargeability anomalies forms the basis for suggesting a new drill-hole targeting. They dictate both the depth and angle at which drilling should be carried out. These results should be applicable to any region where drill-hole targeting in gold exploration may be required.

scholarly journals An empirical model (CH-Therm-2018) of the thermospheric mass density derived from CHAMP

2018 ◽  
Author(s):  
Chao Xiong ◽  
Hermann Lühr ◽  
Michael Schmidt ◽  
Mathis Bloßfeld ◽  
Sergei Rudenko
Keyword(s):  
Empirical Model ◽  
Solar Minimum ◽  
Mass Density ◽  
Precise Orbit Determination ◽  
Wave Pattern ◽  
Magnetic Activity ◽  
Low Earth Orbit ◽  
Naval Research ◽  
Champ Satellite ◽  
Incoherent Scatter

Abstract. Thermospheric drag is the major non-gravitational perturbation acting on Low Earth Orbit (LEO) satellites at altitudes up to 1000 km. The drag depends on the thermospheric density, which is a key parameter in the planning of LEO missions, e.g. their lifetime, collision avoidance, precise orbit determination, as well as orbit and re-entry prediction. In this study, we present an empirical model, named CH-Therm-2018, of the thermospheric mass density derived from 9-year (from August 2000 to July 2009) accelerometer measurements at altitude from 460 to 310 km, from the CHAllenging Minisatellite Payload (CHAMP) satellite. The CHAMP dataset is divided into two 5-year periods with 1-year overlap (from August 2000 to July 2005 and from August 2004 to July 2009), to represent the high-to-moderate and moderate-to-low solar activity conditions, respectively. The CH-Therm-2018 model is a function of seven key parameters, including the height, solar flux index, season (day of year), magnetic local time, geographic latitude and longitude, as well as magnetic activity represented by the solar wind merging electric field. Predictions of the CH-Therm-2018 model agree well with the CHAMP observations (disagreements within ±20 %), and show different features of thermospheric mass density during solar activities, e.g. the March-September equinox asymmetry and the longitudinal wave pattern. We compare the CH-Therm-2018 predictions with the Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar Extended (NRLMSISE-00) model. The result shows that CH-Therm-2018 better predicts the density evolution during the last solar minimum (2008-2009) than the NRLMSISE-00 model. By comparing the Satellite Laser Ranging (SLR) observations of the ANDE-Pollux satellites during August-September 2009, we estimate 6-h scaling factors of thermospheric mass density and obtain a median value of 1.27 ± 0.60, indicating that our model, on average, slightly underestimates the thermospheric mass density at solar minimum.

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