Sinusoidal electric birefringence of dilute rigid‐body suspensions at low field strengths

1986 ◽  
Vol 84 (11) ◽  
pp. 6005-6012 ◽  
Author(s):  
William A. Wegener
Keyword(s):  
Rigid Body ◽  
Electric Birefringence ◽  
Low Field ◽  
Field Strengths

Characteristics of Magnetic Resonance Sequences Used for Imaging Silicone Gel, Saline, and Gel-Saline Implants at Low Field Strengths

1994 ◽  
Vol 29 (8) ◽  
pp. 781-786 ◽  
Author(s):  
STEVEN FRANKEL ◽  
KATHRYN OCCHIPINTI ◽  
LEON KAUFMAN ◽  
DAVID KRAMER ◽  
JOSEPH CARLSON ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Silicone Gel ◽  
Low Field ◽  
Field Strengths

Update of diagnostic preoperative images using low-field interventional MRI for navigation in neurosurgery: rigid-body registration

2005 ◽  
Author(s):  
Martin Kavec ◽  
David Wikler ◽  
Christophe L. M. Phillips ◽  
Lara M. Vigneron ◽  
Marc Levivier ◽  
...  
Keyword(s):  
Rigid Body ◽  
Interventional Mri ◽  
Low Field

scholarly journals Detection of cerebral lactate in vivo during hypoxemia by 1H NMR at relatively low field strengths (1.9 T).

1984 ◽  
Vol 81 (8) ◽  
pp. 2517-2519 ◽  
Author(s):  
K. L. Behar ◽  
D. L. Rothman ◽  
R. G. Shulman ◽  
O. A. Petroff ◽  
J. W. Prichard
Keyword(s):  
1H Nmr ◽  
Low Field ◽  
Field Strengths

scholarly journals On the Validity of the Two-term Approximation of the Electron Distribution Function

1971 ◽  
Vol 24 (4) ◽  
pp. 835 ◽  
Author(s):  
RE Robson ◽  
Kailash Kumar
Keyword(s):  
Distribution Function ◽  
Field Strength ◽  
Drift Velocity ◽  
Electron Distribution ◽  
Electron Distribution Function ◽  
Polynomial Expansion ◽  
Neutral Gas ◽  
Low Field ◽  
Term Approximation ◽  
Field Strengths

The Boltzmann equation for electrons moving in a neutral gas under the influence of an externally applied field is solved by expanding the electron distribution function in terms of Legendre and Sonine polynomials. The solution is given in terms of infinite matrices which have elements ordered by the Sonine polynomial index, and which are dependent upon the field strength. From the structure of the formulae, it is possible to infer that truncation of the Legendre polynomial expansion after two terms is a good approximation at all field strengths. This is supported by calculations of the electron drift velocity at low field strengths, which show that the error introduced by making the two-term approximation is small, even when the deviation from equilibrium is significant. The convergence of the Sonine polynomial expansion is shown to be strongly depende:r;J.t upon field strength, and large matrices are required in the drift velocity formula at even small field strengths.

scholarly journals Effect of Mineral Composition on Transverse Relaxation Time Distributions and MR Imaging of Tight Rocks from Offshore Ireland

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 232
Author(s):  
Stian Almenningen ◽  
Srikumar Roy ◽  
Arif Hussain ◽  
John Georg Seland ◽  
Geir Ersland
Keyword(s):  
Magnetic Field ◽  
Relaxation Time ◽  
Mr Imaging ◽  
Field Strength ◽  
High Field ◽  
Transverse Relaxation Time ◽  
Transverse Relaxation ◽  
The Core ◽  
Low Field ◽  
Field Strengths

In this paper, we investigate the effect of magnetic field strength on the transverse relaxation time constant (T2) in six distinct core plugs from four different rock types (three sandstones, one basalt, one volcanic tuff and one siltstone), retrieved from offshore Ireland. The CPMG pulse-sequence was used at two different magnetic field strengths: high-field at 4.70 T and low-field at 0.28 T. Axial images of the core plugs were also acquired with the RAREst sequence at high magnetic field strength. Thin-sections of the core plugs were prepared for optical imaging and SEM analysis, and provided qualitative information on the porosity and quantification of the elemental composition of the rock material. The content of iron varied from 4 wt. % to close to zero in the rock samples. Nevertheless, the effective T2 distributions obtained at low-field were used to successfully predict the porosity of the core plugs. Severe signal attenuations from internal magnetic gradients resulted in an underestimation of the porosity at high-field. No definitive trend was identified on the evolution of discrete relaxation time components between magnetic field strengths. The low-field measurements demonstrate that NMR is a powerful quantitative tool for petrophysical rock analysis as compared to thin-section analysis. The results of this study are of interest to the research community who characterizes natural gas hydrates in tight heterogeneous core plugs, and who typically relies on MR imaging to distinguish between solid hydrates and fluid phases. It further exemplifies the importance of selecting appropriate magnetic field strengths when employing NMR/MRI for porosity calculation in tight rock.

Sign in / Sign up

Export Citation Format

Share Document