Magnetotelluric tensor decomposition: Part II, Examples of a basic procedure

Geophysics ◽  
1998 ◽  
Vol 63 (6) ◽  
pp. 1898-1907 ◽  
Author(s):  
F. E. M. (Ted) Lilley
Keyword(s):  
Tensor Decomposition ◽  
Companion Paper ◽  
Impedance Tensor ◽  
The Real ◽  
Common Features ◽  
Basic Procedure ◽  
Decomposition Procedure ◽  
Valid Data ◽  
Erroneous Data ◽  
Good Agreement

The decomposition procedure suggested for magnetotelluric (MT) data in a companion paper is illustrated by examples. Adjacent pairs of stations are examined to test for common features in their MT response. The method analyzes the real and quadrature parts of an impedance tensor separately, and the results for the real and quadrature parts are compared, and in some cases combined, at the end. Values are obtained which are interpreted directly in terms of nearest 2-D principal impedances, local geologic strike, and regional geologic strike. The requirement for valid data derived in the companion paper, that [Formula: see text] together with [Formula: see text], is shown to be a useful criterion in the winnowing of erroneous data. The examples presented typically show the direction interpreted as local geologic strike to be well determined, period independent, and consistent between real and quadrature MT matrices. In these examples, however, the direction interpreted as regional geologic strike is period dependent and not in good agreement between real and quadrature MT matrices. These results suggest caution is desirable in the use of period‐independent galvanic distortion models, which should be checked first with regional strike determinations.

Magnetotelluric tensor decomposition: Part I, Theory for a basic procedure

Geophysics ◽  
1998 ◽  
Vol 63 (6) ◽  
pp. 1885-1897 ◽  
Author(s):  
F. E. M. (Ted) Lilley
Keyword(s):  
Pure Shear ◽  
General Theorem ◽  
Tensor Decomposition ◽  
Impedance Tensor ◽  
Model Calculations ◽  
Tensor Decompositions ◽  
The Real ◽  
Mohr Circle ◽  
Basic Procedure ◽  
D Model

The problem of expressing a general 3-D magnetotelluric (MT) impedance tensor in the form of a 2-D tensor that has been distorted in some way is addressed first in terms of a general theorem. This theorem shows that when the real and quadrature parts of a tensor are analyzed separately as distinct matrices, all that is necessary to make a matrix with 2-D characteristics from one with 3-D characteristics is to allow the electric and magnetic observing axes to rotate independently. The process is then examined in terms of the operations of twist and pure shear (“split”) on such matrices. Both of two basic sequences of split after twist, and twist after split, produce a typical 3-D matrix from one initially 1-D, with the parameters of split contributing 2-D characteristics to the final matrix. Taken in reverse, these sequences offer two basic paths for the decomposition of a 3-D matrix, and are seen to be linked to the initial theorem. The various operations on matrices are expressed diagrammatically using the Mohr circle construction, of which it is demonstrated two types are possible. Mohr circles of an observed MT tensor display all the information held by the tensor, and the two types of circle construction respectively make clear whether particular data are well suited to modeling by either split after twist, or twist after split. Generally, tensor decompositions may be displayed by charting their progress in Mohr space. The Mohr construction also displays the invariants of a tensor and shows that tensor decomposition can be viewed as a process of determining an appropriate set of invariants. An expectation that the origin of axes should be outside every circle categorizes as irregular any tensors which, in either the real or quadrature part, do not satisfy a [Formula: see text] criterion. The theory of the present paper applies equally to procedures for distorting 1-D and 2-D model calculations for the purpose of matching observed 3-D data.

scholarly journals Parameter Identification of Tractor-Semitrailer Model under Steering and Braking

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Yiming Li ◽  
Qin Shi ◽  
Duoyang Qiu
Keyword(s):  
Genetic Algorithm ◽  
Field Test ◽  
Test Data ◽  
Performance Testing ◽  
Roll Angle ◽  
Lookup Table ◽  
The Real ◽  
Yaw Rate ◽  
Roll Rate ◽  
Good Agreement

This paper describes a valuable linear yaw-roll tractor-semitrailer (TST) model with five-degree-of-freedom (DOFs) for control algorithm development when steering and braking. The key parameters, roll stiffness, axle cornering stiffness, and fifth-wheel stiffness, are identified by the genetic algorithm (GA) and multistage genetic algorithm (MGA) based on TruckSim outputs to increase the accuracy of the model. Thus, the key parameters of the simplified model can be modified according to the real-time vehicle states by online lookup table and interpolation. The TruckSim vehicle model is built referring to the real tractor (JAC-HFC4251P1K7E33ZTF6×2) and semitrailer (Luyue LHX9406) used in the field test later. The validation of the linear yaw-roll model of a tractor-semitrailer using field test data is presented in this paper. The field test in the performance testing ground is detailed, and the test data of roll angle, roll rate, and yaw rate are compared with the outputs of the model with maps of the key parameters. The results indicate that the error of the tractor’s roll angle and semitrailer’s roll angle between model data and test data is 1.13% and 1.24%, respectively. The roll rate and yaw rate of the tractor and semitrailer are also in good agreement.

CALCULATION OF THE MAGNETOTELLURIC TENSOR IMPEDANCE: ANALYSIS OF BAND‐LIMITED MT SIGNAL PAIRS

Geophysics ◽  
1975 ◽  
Vol 40 (5) ◽  
pp. 790-797 ◽  
Author(s):  
Larry R. Grillot
Keyword(s):  
Field Data ◽  
Fourier Coefficients ◽  
Impedance Analysis ◽  
Impedance Tensor ◽  
Period Range ◽  
Tensor Impedance ◽  
Band Limited ◽  
Good Agreement ◽  
Least Squares Approach

A method of analyzing the tensor nature of magnetotelluric fields from short independent sections of filtered MT data is presented in which: (1) horizontal field components are filtered at chosen periods; (2) short sections which show a well defined signal over 3–4 cycles are selected from the records; (3) the polarizations of these short record sections are plotted; and (4) Fourier coefficients calculated for section pairs showing differing magnetic field polarizations are then used to calculate the elements of the impedance tensor. Results of this analysis performed on MT field data show that the use of MT signal pairs yields uniform principal resistivities for calculations using several different section pairs of the same period. These results also illustrate internal consistency of the resistivity estimates over the complete period range of the data (30–7500 sec). A brief comparison of the MT pairs calculations and results derived from a least‐squares approach at a selected period shows good agreement between the two methods. The overall results suggest that the use of independent signal pairs in the determination of the tensor impedance could complement more traditional methods in some cases.

Spatial averaging of the vertical magnetic field in central‐loop configuration

Geophysics ◽  
1993 ◽  
Vol 58 (10) ◽  
pp. 1507-1510 ◽  
Author(s):  
Wei Qian ◽  
Laust B. Pedersen
Keyword(s):  
Tensor Decomposition ◽  
Data Interpretation ◽  
Impedance Tensor ◽  
Logarithmic Scale ◽  
Resistivity Structure ◽  
One Dimensional ◽  
Transient Electromagnetic ◽  
The Earth ◽  
Band Limited ◽  
Central Loop

Local resistivity heterogeneities can cause static shifts in the magnetotelluric (MT) impedance tensor that severely complicate data interpretation; the apparent resistivity is shifted on a logarithmic scale across the recorded frequency range while the phase has a band‐limited response. Different techniques such as electromagnetic array profiling (EMAP) (Torres‐Verdín and Bostick, 1992) and tensor decomposition (Zhang et al., 1987; Groom and Bailey, 1989; 1991) have been developed in the MT community to recognize and remove static shifts. Sternberg, et al. (1988) and Pellerin and Hohmann (1990) suggest that central‐loop transient electromagnetic (TEM) soundings can obtain an unbiased estimate of the regional resistivity structure of the earth and thereby correct for magnetotelluric static shifts. The regional resistivity structure of the earth must be one‐dimensional (1-D) for this method to work well.

Sound Insulation of Open Screens: Measurement by Impulse Response Analysis

1997 ◽  
Vol 4 (1) ◽  
pp. 51-72 ◽  
Author(s):  
R. Lyons ◽  
B.M. Gibbs
Keyword(s):  
Impulse Response ◽  
Standard Method ◽  
Transmission Loss ◽  
Practical Method ◽  
Companion Paper ◽  
Sound Insulation ◽  
Response Analysis ◽  
Impulse Response Analysis ◽  
Method Of Measurement ◽  
Good Agreement

In a companion paper. Impulse Response Analysis methods were developed as a practical method of measuring the sound insulation of panels, both as partitions and as solid screens and a method for comparing the results with the standard method of measurement for transmission loss, ISO 140, was demonstrated. In this paper studies are presented on the application of the method to more complex open forms of screen. A prediction model has been used for the simpler form of screen, which shows good agreement with measurements. For the more complicated screens, which provide greater sound insulation, the results are compared with standard ISO 140 measurements.

The Use of TPMC for Designing MRFs Equipped with FREEDAM Connections: Performance Evaluation

2018 ◽  
Vol 763 ◽  
pp. 983-991 ◽  
Author(s):  
Rosario Montuori ◽  
Elide Nastri ◽  
Vincenzo Piluso ◽  
Simona Streppone
Keyword(s):  
Performance Evaluation ◽  
Dynamic Analysis ◽  
Design Procedure ◽  
Incremental Dynamic Analysis ◽  
Companion Paper ◽  
Collapse Mechanism ◽  
The Real ◽  
Interstorey Drift ◽  
Global Type ◽  
Steel Mrfs

The work herein presented is devoted to the validation of TPMC design procedure applied to steel MRFs equipped with FREEDAM dampers located at beam-to-column joints. The seismic performances evaluations of the designed structure have been carried out by means of both Push-over analysis and Incremental Dynamic Analysis. In particular, the Push-over analysis aims to confirm the real development of a collapse mechanism of global type, while, through IDA analysis, Maximum Interstorey Drift and Top Residual Displacement performed by the designed structures have been pointed out. For this reason, a MRF whose design procedure by TPMC is detailed in a companion paper has been subjected to both push-over and IDA analysis.

Unification of the Electronic Phase Diagrams of the RO1−xFxFeAs-Compounds by Using the Real Fluorine Content

2010 ◽  
Vol 1254 ◽  
Author(s):  
A. Köhler ◽  
G. Behr
Keyword(s):  
Phase Diagrams ◽  
Fluorine Content ◽  
Published Data ◽  
Initial Weight ◽  
X Ray ◽  
The Real ◽  
Electronic Phase ◽  
Consistent Picture ◽  
Good Agreement

AbstractMeasurements of the actual fluorine content x in the RO1−xFxFeAs-samples by wavelength-dispersive X-ray spectroscopy (WDX) reveal sample dependent discrepancies to the nominal fluorine content (initial weight). In particular for SmO1−xFxFeAs, the measured value only reached approximately half of the required value. In the lanthanum compound LaO1−xFxFeAs, we found a good agreement mainly for x>0.05, but the fluorine hardly goes into the sample for x<0.05. We used the measured fluorine content when plotting the electronic phase diagrams again and find a more consistent picture occurs as well for our samples as for comparison with the divers published data.

scholarly journals THE NUCLEAR SPIN RESONANCE SPECTRUM OF Al27 IN SPODUMENE

1958 ◽  
Vol 36 (10) ◽  
pp. 1295-1307 ◽  
Author(s):  
L. B. Robinson
Keyword(s):  
Nuclear Spin ◽  
Resonance Spectrum ◽  
Companion Paper ◽  
Quadrupole Interactions ◽  
Resonance Frequencies ◽  
Spin Resonance ◽  
Theoretical Predictions ◽  
Induction Type ◽  
First Time ◽  
Good Agreement

An experimental study has been made of the nuclear spin resonance spectrum of Al27 in a single crystal of spodumene (LiAl(SiO3)2) over a range of external magnetic field H0 wide enough [Formula: see text] to bridge for the first time the gap between pure quadrupole spectra (R = 0) and Zeeman spectra slightly perturbed by quadrupole interactions [Formula: see text]. Experimental results on the resonance frequencies and relative signal amplitudes obtained with an induction type of nuclear resonance spectrometer are described, and are found to be in good agreement with the theoretical predictions given in the preceding companion paper.

scholarly journals Geometric estimation of volcanic eruption column height from GOES-R near-limb imagery – Part 2: Case studies

2021 ◽  
Author(s):  
Ákos Horváth ◽  
Olga A. Girina ◽  
James L. Carr ◽  
Dong L. Wu ◽  
Alexey A. Bril ◽  
...  
Keyword(s):  
Volcanic Eruption ◽  
Temperature Inversion ◽  
Companion Paper ◽  
Column Height ◽  
Eruption Column ◽  
Side View ◽  
Temperature Method ◽  
A New Technique ◽  
Tropopause Temperature ◽  
Good Agreement

Abstract. In a companion paper (Horváth et al., 2021), we introduced a new technique to estimate volcanic eruption column height from extremely oblique near-limb geostationary views. The current paper demonstrates and validates the technique in a number of recent eruptions, ranging from ones with weak columnar plumes to subplinian events with massive umbrella clouds and overshooting tops that penetrate the stratosphere. Due to its purely geometric nature, the new method is shown to be unaffected by the limitations of the traditional brightness temperature method, such as height underestimation in subpixel and semitransparent plumes, ambiguous solutions near the tropopause temperature inversion, or the lack of solutions in undercooled plumes. The side view height estimates were in good agreement with plume heights derived from ground-based video and satellite stereo observations, suggesting they can be a useful complementary to established techniques.

scholarly journals The Creep of Ice Shelves: Interpretation of Observed Behaviour

1973 ◽  
Vol 12 (64) ◽  
pp. 55-70 ◽  
Author(s):  
R. H. Thomas
Keyword(s):  
Companion Paper ◽  
Laboratory Work ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Observed Behaviour ◽  
Flow Law ◽  
Good Agreement

AbstractAvailable measurements of creep rates and dimensions of ice shelves are used, in conjunction with equations derived in a companion paper (Thomas, 1973), to evaluate the flow law parametersBandnfor stresses down to 104N m−2. The results show good agreement with laboratory work at higher stresses. Adoption of these values ofBandnenables us to examine the restraining effects on an ice shelf of obstructions such as areas of grounding.

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