Numerical estimation of Fricke–Morse impedance model parameters using single-frequency sinusoidal excitation

We analyze the relationship between induced polarization (IP) parameters and the specific surface area normalized to the pore volume [Formula: see text] for an extensive sample database. We find that a single linear imaginary conductivity-[Formula: see text] relation holds across a range of single-frequency IP data sets composed of sandstones and unconsolidated sediments that lack an appreciable metallic mineral content. We also apply a recent approach defined as Debye decomposition (DD) to determine normalized chargeability [Formula: see text], a global estimate of polarization magnitude from available spectral IP (SIP) data sets. A strong linear relationship between [Formula: see text] and [Formula: see text] is also found across multiple data sets. However, SIP model parameters determined for samples containing metallic minerals are approximately two orders of magnitude greater than for the model parameters estimated for the nonmetallic sample database. We propose a concept of “polarizability of the mineral-fluid interface per unit [Formula: see text]” to explain this difference, which is supported by the observed dependence of IP parameters on fluid conductivity between sample types. We suggest that this linear IP-[Formula: see text] relation can be considered the IP equivalent of the classical Archie empirical relation. Whereas the Archie relation describes a power-law relation between electrical conductivity due to electrolytic conduction through the available interconnected pore volume, the IP-[Formula: see text] relation is an equivalent relation between mineral-fluid interfacial polarization and available pore surface area.

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Positioning performance of the NTCM model driven by GPS Klobuchar model parameters

Journal of Space Weather and Space Climate ◽

10.1051/swsc/2018009 ◽

2018 ◽

Vol 8 ◽

pp. A20 ◽

Cited By ~ 3

Author(s):

Mohammed Mainul Hoque ◽

Norbert Jakowski ◽

Jens Berdermann

Keyword(s):

Single Frequency ◽

Activity Period ◽

Model Parameters ◽

Signal Delay ◽

Correction Algorithm ◽

Ionospheric Correction ◽

Model Driven ◽

Position Errors ◽

Klobuchar Model ◽

Range Error

Users of the Global Positioning System (GPS) utilize the Ionospheric Correction Algorithm (ICA) also known as Klobuchar model for correcting ionospheric signal delay or range error. Recently, we developed an ionosphere correction algorithm called NTCM-Klobpar model for single frequency GNSS applications. The model is driven by a parameter computed from GPS Klobuchar model and consecutively can be used instead of the GPS Klobuchar model for ionospheric corrections. In the presented work we compare the positioning solutions obtained using NTCM-Klobpar with those using the Klobuchar model. Our investigation using worldwide ground GPS data from a quiet and a perturbed ionospheric and geomagnetic activity period of 17 days each shows that the 24-hour prediction performance of the NTCM-Klobpar is better than the GPS Klobuchar model in global average. The root mean squared deviation of the 3D position errors are found to be about 0.24 and 0.45 m less for the NTCM-Klobpar compared to the GPS Klobuchar model during quiet and perturbed condition, respectively. The presented algorithm has the potential to continuously improve the accuracy of GPS single frequency mass market devices with only little software modification.

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Extracting the Cole-Cole impedance model parameters without direct impedance measurement

Electronics Letters ◽

10.1049/el.2010.1924 ◽

2010 ◽

Vol 46 (20) ◽

pp. 1367 ◽

Cited By ~ 56

Author(s):

A.S. Elwakil ◽

B. Maundy

Keyword(s):

Impedance Measurement ◽

Model Parameters ◽

Impedance Model

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An Improved BDS Satellite-Induced Code Bias Correction Model Considering the Consistency of Multipath Combinations

Remote Sensing ◽

10.3390/rs10081189 ◽

2018 ◽

Vol 10 (8) ◽

pp. 1189 ◽

Cited By ~ 4

Author(s):

Lin Pan ◽

Fei Guo ◽

Fujian Ma

Keyword(s):

Piecewise Linear ◽

Satellite System ◽

Single Frequency ◽

Model Parameters ◽

Correction Model ◽

Cycle Slips ◽

Linear Correction ◽

Code Bias ◽

Navigation Signals ◽

Orbit Types

The satellite-induced systematic biases were identified to exist in the code observations from BeiDou navigation satellite system (BDS) satellites using multipath (MP) combinations. The current correction model for satellite-induced code bias (SICB) does not take into account the consistency of MP combinations, which limits the accuracy of the developed model. Both the cycle slips and different tracking of a satellite at different stations can affect the absolute values of MP combinations, although the variations remain unchanged. An improved SICB piecewise linear correction model as a function of elevations is proposed. We estimate the model parameters for each frequency and for each satellite. The single-difference of MP combinations in the domain of elevation angles is carried out to remove the unknown ambiguities and stable hardware delays so that the SICB modeling is free of the effects of MP combination inconsistency. In addition, a denser elevation node separation of 1°, rather than the 10° usually employed by the traditional model, is used to describe the more precise SICB variations. The SICB corrections show significant differences among orbit types and frequency bands. The SICB variations have much less effect on Inclined Geosynchronous Orbit (IGSO) satellites than on Medium Earth Orbit (MEO) satellites for the regional BDS (BDS-2). The B1 signal has the largest SICB corrections, which can be up to 0.9 m close to zenith for BDS-2 MEO satellites, and the B2 signal follows. After adding the SICB corrections to the code observations, the elevation-dependent code biases vanish, and we can obtain improved code observations. After applying the improved SICB correction model, the root mean square (RMS) values of MP combination time series are reduced by 7%, 6% and 2%, and 18%, 14% and 5% on the B1, B2 and B3 frequencies for the BDS-2 IGSO and MEO satellites, respectively. For comparison, we also establish the traditional SICB correction model. With the traditional SICB correction model, the corresponding RMS MP combinations are smaller than those of uncorrected MP series, but slightly larger than those of corrected MP series using the improved SICB correction model. To validate the effectiveness and correctness of our proposed model, single-frequency precise point positioning (PPP) processing with BDS-2 MEO and IGSO satellites is conducted. An accuracy improvement of 24%, 19% and 89%, and 7%, 7% and 6% for the single-frequency PPP applying the improved SICB corrections over the case without SICB corrections and the case using the traditional SICB corrections in east, north and vertical directions is achieved, respectively. Although only centimeter-level SICB variations could be observed for the two legacy signals B1 and B3 and the three new navigation signals B1C, B2a and B2b transmitted by the satellites of global BDS demonstration system (BDS-3S), we still establish an effective SICB correction model on the B1 and B3 frequencies for BDS-3S IGSO satellites, and the RMS MP combinations are reduced by 1–4% after applying the improved SICB corrections.

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RATE-DEPENDENT ELASTO-SLIDE MODEL FOR SINGLE AND DUAL FREQUENCY MR LAG DAMPER BEHAVIOR

International Journal of Modern Physics B ◽

10.1142/s0217979205030542 ◽

2005 ◽

Vol 19 (07n09) ◽

pp. 1527-1533 ◽

Cited By ~ 2

Author(s):

WEI HU ◽

NORMAN M. WERELEY

Keyword(s):

Domain Model ◽

Single Frequency ◽

Model Parameters ◽

Dual Frequency ◽

Bingham Plastic ◽

Rate Dependent ◽

In Series ◽

Stiff Spring ◽

Rotor Dynamic

In order to capture MR lag damper behavior accurately in the context of helicopter rotor dynamic analyses, a physically motivated rate-dependent elasto-slide model was developed based on the Bingham plastic model. This time-domain model uses a rate-dependent slide and a parallel viscous damper to simulate the yield behavior of the MR fluid and uses a stiff spring in series with the slide to represent the preyield stiffness. A method of determination of the model parameters was introduced using MR damper single frequency hysteresis data. The fidelity of the model was justified by the good correlation between modeling results and experimental steady-state data over a wide amplitude and moderate frequency range. Significantly, the rate-dependent elasto-slide model is applicable in predicting response under single and dual frequency loading conditions encountered by an MR lag damper.

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