Equivalent current density reconstruction for microwave imaging purposes

1989 ◽  
Vol 37 (5) ◽  
pp. 910-916 ◽  
Author(s):  
S. Caorsi ◽  
G.L. Gragnani ◽  
M. Pastorino
Keyword(s):  
Current Density ◽  
Microwave Imaging ◽  
Equivalent Current

scholarly journals A model for estimating the relation between the Hall to Pedersen conductance ratio and ground magnetic data derived from CHAMP satellite statistics

2007 ◽  
Vol 25 (3) ◽  
pp. 721-736 ◽  
Author(s):  
L. Juusola ◽  
O. Amm ◽  
K. Kauristie ◽  
A. Viljanen
Keyword(s):  
Current Density ◽  
Geomagnetic Latitude ◽  
Magnetic Data ◽  
Equivalent Current ◽  
Champ Satellite ◽  
Long Time ◽  
Conductance Ratio ◽  
Ground Magnetic ◽  
Eiscat Radar ◽  
Magnetic Satellite

Abstract. The goal of this study is to find a way to statistically estimate the Hall to Pedersen conductance ratio α from ground magnetic data. We use vector magnetic data from the CHAMP satellite to derive this relation. α is attained from magnetic satellite data using the 1-D Spherical Elementary Current Systems (SECS). The ionospheric equivalent current density can either be computed from ground or satellite magnetic data. Under the required 1-D assumption, these two approaches are shown to be equal, which leads to the advantage that the statistics are not restricted to areas covered by ground data. Unlike other methods, using magnetic satellite measurements to determine α ensures reliable data over long time sequences. The statistical study, comprising over 6000 passes between 55° and 76.5° northern geomagnetic latitude during 2001 and 2002, is carried out employing data from the CHAMP satellite. The data are binned according to activity and season. In agreement with earlier studies, values between 1 and 3 are typically found for α. Good compatibility is found, when α attained from CHAMP data is compared with EISCAT radar measurements. The results make it possible to estimate α from the east-west equivalent current density Jφ; [A/km]: α=2.07/(36.54/|Jφ|+1) for Jφ<0 (westward) and α=1.73/(14.79/|Jφ+1) for Jφ0 (eastward). Using the same data, statistics of ionospheric and field-aligned current densities as a function of geomagnetic latitude and MLT are included. These are binned with respect to activity, season and IMF BZ and BY. For the first time, all three current density components are simultaneously studied this way on a comparable spatial scale. With increasing activity, the enhancement and the equatorward expansion of the electrojets and the R1 and R2 currents is observed, and in the nightside, possible indications of a Cowling channel appear. During southward IMF BZ, the electrojets and the R1 and R2 currents are stronger and clearer than during northward BZ. IMF BY affects the orientation of the pattern.

On the Passivity of Iron★

CORROSION ◽  
1955 ◽  
Vol 11 (7) ◽  
pp. 32-36 ◽  
Author(s):  
KARL FRIEDRICH BONHOEFFER
Keyword(s):  
Nitric Acid ◽  
Current Density ◽  
Nitrous Acid ◽  
Redox System ◽  
Equivalent Current ◽  
Passivation Current Density ◽  
Passivation Potential

Abstract Descriptions are given of the various phenomena associated with the passivation and reactivation of iron in concentrated nitric acid. Covered are apparent and true passivation potential, apparent and true passivation current density, passivity producing and passivity maintaining current density. Information is given also on equivalent current density in a redox system, the role of nitrous acid in passivation by concentrated nitric acid, the corrosion of passive iron, refractoriness toward activation, rhythms and activity waves.

scholarly journals EARLY DETECTION OF BREAST CANCER USING ULTRA WIDE BAND SLOT ANTENNA

SINERGI ◽  
2019 ◽  
Vol 23 (2) ◽  
pp. 115
Author(s):  
Yusnita Rahayu ◽  
Immanuel Waruwu
Keyword(s):  
Breast Cancer ◽  
Early Detection ◽  
Current Density ◽  
Tumor Size ◽  
Microstrip Antenna ◽  
The United States ◽  
Microwave Imaging ◽  
Ultra Wideband ◽  
Slot Antenna ◽  
Safe Alternative

Breast cancer is the transformation of normal cells in the breast area into a malignant tumor, which is the second largest disease as a cause of death for women. Early detection is one way to avoid significant risks in breast cancer.  X-ray mammography and magnetic resonance imaging (MRI) techniques are used to detect breast cancer. However, those techniques have several limitations. Ultra-wideband (UWB) microwave imaging, approved by The Federal Communications Commission (FCC) in the United States, has promising capabilities in detecting breast cancer. Microwave imaging uses a microstrip antenna that has the advantage of convenience, potentially low cost, and is a non-ionized and safe alternative. In this paper, the ultra-wideband microstrip antenna for breast cancer detection is proposed. The antenna was designed by adding some rectangular slots on a rectangular patch to meet the UWB specifications. The antenna works well at 8.41 GHz to 10.29 GHz with directivity of 6.451 dBi and SAR value of 1.6 W / kg. The antenna was simulated with breast phantom. The tumor sizes of 6 mm and 10 mm are added to evaluate the E/H fields and current density with and without tumor. The highest E-Field value of 928.8 V / m was obtained at 10 GHz with a 10 mm tumor size.  The highest H-Field value of 4.06 V / m was achieved at 10 GHz with a 6 mm tumor size. From the simulation, the E/H-field and current density are higher if there is a tumor in the breast compared to the breast without the tumor.

When Size Matters: Large Electrodes Induce Greater Stimulation-related Cutaneous Discomfort Than Smaller Electrodes at Equivalent Current Density

2014 ◽  
Vol 7 (3) ◽  
pp. 460-467 ◽  
Author(s):  
Zsolt Turi ◽  
Géza Gergely Ambrus ◽  
Kerrie-Anne Ho ◽  
Titas Sengupta ◽  
Walter Paulus ◽  
...  
Keyword(s):  
Current Density ◽  
Equivalent Current
Sign in / Sign up

Export Citation Format

Share Document