scholarly journals Improving of the Probing Signal’s Spectral Content for Devices Nuclear Magnetic Logging

2021 ◽  
Vol 26 (2) ◽  
Author(s):  
Anton Yu. Manzhelii ◽  
Artur Volodymyrovych Zahranychnyi
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Output Signal ◽  
Spectral Composition ◽  
Urgent Task ◽  
Wide Range ◽  
Probing Signal ◽  
Harmonic Composition ◽  
Nuclear Magnetic

The method of nuclear magnetic logging (NML) allows to distinguish easily enough the intervals in which there are hydrocarbons and to forecast their extraction. Moreover, the principles of measuring using this method are simple enough, despite the difficulties of processes. There were described method of improving spectral composition of probing voltage NML device in this article. The disadvantage of the method is that the resonance area covers all reservoir fluids. Therefore, search for a way to reduce the frequency spectrum and extend the range of the device of nuclear magnetic resonance is a rather urgent task. In the article is stated that within conducting researches is necessary probing signals of large capacity. In this case, it is more appropriate to use switch mode of the power converters. The system of multilevel inverter is created on the base of these converters that allows to get probing signal simply enough. A three-level inverter that generates high-frequency pulses is considered. A virtual model of the converter is constructed together with smoothing and resonant filters, which generate the probing voltage in nuclear magnetic resonance (NMR) devices, using a modified Carr-Purcell-Meiboom-Gill sequence. The result is a wide range of voltages with side harmonics, which have the significant influence on the output signal relative to the base frequency which the NMR device is tuned. The analysis of the harmonic composition of this voltage is conducted. Calculations of intermodulation distortion coefficients for the first and two side harmonics are given. To reduce the influence of side harmonics in the output signal on the quality of measurement by NMR devices, it is proposed to implement additional generators with the phase difference between the side harmonic and the initial phase will be a half of period. The inductors used are transformers that have a ratio of primary and secondary windings of 1: 1 and the secondary winding has the same value of inductance as the replaced coil that was in the model without modifications. Anti-phase side harmonic generators are connected to the primary windings. In this way additionally implemented a galvanic isolation between the generator and the main signal. As a result of simulation of such a converter is obtained an alternative spectral composition of the output signal. After calculations and comparison of the obtained coefficients, it is shown that the proposed method really improves the spectral composition of the output signal. The disadvantages of using this method of spectrum improvement are considered as well. The relative voltage improvement in the case of a 30 ohms load is calculated. The simulation results of the proposed method show an improvement in the spectral composition of the probing voltage by ~ 2.68 times. With this method, it is possible to dampen unwanted side harmonics by adjusting the appropriate frequencies and initial phases so that the generator is always running in antiphase.

Physiological Uses of Nuclear Magnetic Resonance

Physiology ◽  
1989 ◽  
Vol 4 (2) ◽  
pp. 79-84
Author(s):  
MJ Avison ◽  
NJ Siegel
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Human Studies ◽  
Technical Developments ◽  
Wide Range ◽  
Nuclear Magnetic

Nuclear magnetic resonance provides physiologists with a flexible means of measuring a wide range of cell and tissue parameters. These measurements can be nondestructive and noninvasive. Recent technical developments have enabled several of these approaches to be applied to human studies.

Solid State NMR Measurements for Preliminary Lifetime Assessments in λ-Irradiated and Thermally Aged Siloxane Elastomers

2004 ◽  
Vol 851 ◽  
Author(s):  
Sarah C. Chinn ◽  
Julie L. Herberg ◽  
April M. Sawvel ◽  
Robert S. Maxwell
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Magnetic Resonance ◽  
Coupling Constants ◽  
Screening Tools ◽  
Engineering Properties ◽  
Relaxation Rates ◽  
Nmr Studies ◽  
Wide Range ◽  
Nuclear Magnetic

ABSTRACTSiloxanes have a wide variety of applications throughout the aerospace industry which take advantage of their exceptional insulating and adhesive properties and general resilience. They also offer a wide range of tailorable engineering properties with changes in composition and filler content. They are, however, subject to degradation in radiatively and thermally harsh environments. We are using solid state nuclear magnetic resonance techniques to investigate changes in network and interfacial structure in siloxane elastomers and their correlations to changes in engineering performance in a series of degraded materials. Nuclear magnetic resonance (NMR) parameters such as transverse (T2) relaxation times, cross relaxation rates, and residual dipolar coupling constants provide excellent probes of changes crosslink density and motional dynamics of the polymers caused by multi-mechanism degradation. The results of NMR studies on aged siloxanes are being used in conjunction with other mechanical tests to provide insight into component failure and degradation kinetics necessary for preliminary lifetime assessments of these materials as well as into the structure-property relationships of the polymers. NMR and magnetic resonance imaging (MRI) results obtained both from high resolution NMR spectrometers as well as low resolution benchtop NMR screening tools will be presented.

Simultaneous In Situ Monitoring of Trimethoxysilane Hydrolysis Reactions Using Raman, Infrared, and Nuclear Magnetic Resonance (NMR) Spectroscopy Aided by Chemometrics and Ab Initio Calculations

2018 ◽  
Vol 72 (9) ◽  
pp. 1404-1415
Author(s):  
Xiaoyun Chen ◽  
Donald Eldred ◽  
Jing Liu ◽  
Hsu Chiang ◽  
Xianghuai Wang ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Reaction Rates ◽  
In Situ Monitoring ◽  
Spectroscopic Techniques ◽  
Wide Range ◽  
Nuclear Magnetic ◽  
Hydrolysis Reactions

Sol-gels are found in many different scientific fields and have very broad applications. They are often prepared by the hydrolysis and condensation of alkoxysilanes such as trimethoxysilanes, which are commonly used as precursors in the preparation of silsequioxanes via the sol-gel process. The reaction rates of such reactions are influenced by a wide range of experimental factors such as temperature, pH, catalyst, etc. In this study, we combined multiple in situ spectroscopic techniques to monitor the hydrolysis and partial condensation reactions of methyltrimethoxysilane and phenyltrimethoxysilane. A rich set of kinetics information on intermediate species of the hydrolysis reactions were obtained and used for kinetics modeling. Raman and nuclear magnetic resonance (NMR) spectroscopy provided the most information about hydrolysis and NMR provided the most information about condensation. A quantitative method based on Raman spectra to quantify the various transient intermediate hydrolysis products was developed using NMR as the primary method, which can be deployed in the field where it is impractical to carry out NMR measurements.

scholarly journals Coupled magnetic resonance and electrical resistivity tomography: An open-source toolbox for surface nuclear-magnetic resonance

Geophysics ◽  
2020 ◽  
Vol 85 (3) ◽  
pp. F53-F64 ◽  
Author(s):  
Nico Skibbe ◽  
Raphael Rochlitz ◽  
Thomas Günther ◽  
Mike Müller-Petke
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Electrical Resistivity ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Water Content ◽  
Open Source ◽  
Electrical Resistivity Tomography ◽  
Resistivity Tomography ◽  
Wide Range ◽  
Nuclear Magnetic

Nuclear-magnetic resonance (NMR) is a powerful tool for groundwater system imaging. Ongoing developments in surface NMR, for example, multichannel devices, allow for investigations of increasingly complex subsurface structures. However, with the growing complexity of field cases, the availability of appropriate software to accomplish the in-depth data analysis becomes limited. The open-source Python toolbox coupled magnetic resonance and electrical resistivity tomography (COMET) provides the community with a software for modeling and inversion of complex surface NMR data. COMET allows the NMR parameters’ water content and relaxation time to vary in one dimension or two dimensions and accounts for arbitrary electrical resistivity distributions. It offers a wide range of classes and functions to use the software via scripts without in-depth programming knowledge. We validated COMET to existing software for a simple 1D example. We discovered the potential of COMET by a complex 2D case, showing 2D inversions using different approximations for the resistivity, including a smooth distribution from electrical resistivity tomography (ERT). The use of ERT-based resistivity results in similar water content and relaxation time images compared with using the original synthetic block resistivity. We find that complex inversion may indicate incorrect resistivity by non-Gaussian data misfits, whereas amplitude inversion shows well-fitted data, but leading to erroneous NMR models.

Nuclear magnetic resonance studies of the solution chemistry of metal complexes. XVII. Formation constants for the complexation of methylmercury by sulfhydryl-containing amino acids and related molecules

1981 ◽  
Vol 59 (10) ◽  
pp. 1505-1514 ◽  
Author(s):  
R. Stephen Reid ◽  
Dallas L. Rabenstein
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Formation Constants ◽  
Solution Chemistry ◽  
The Other ◽  
Mercaptoacetic Acid ◽  
Resonance Spectroscopy ◽  
Mercaptosuccinic Acid ◽  
Wide Range ◽  
Nuclear Magnetic

Complexation of methylmercury, CH3Hg(II), by mercaptoacetic acid, mercaptoethanol, mercaptosuccinic acid, cysteine, penicillamine, homocysteine, and N-acetylpenicillamine has been studied by 1H nuclear magnetic resonance spectroscopy. The equilibrium constant for displacement of mercaptoacetic acid from its CH3Hg(II) complex by each of the other thiols was measured over a wide range of pH. From the displacement constants and a literature value for the formation constant of the mercaptoethanol complex of CH3Hg(II), formation constants were calculated for thiol complexes with the other ligands, including microscopic formation constants for cysteine and penicillamine complexes in which the amino groups are protonated and deprotonated. Detailed information on the acid–base chemistry of the free amino and carboxylic acid groups in the complexes is also reported. The formation constants increase as the Brønsted basicity of the deprotonated sulfhydryl group increases according to the relation log Kf = pK + 6.86. The conditional formation constants of the CH3Hg(II) complexes are strongly pH dependent due to competitive reactions involving hydrogen and hydroxide ions at low and high pH. The results at physiological pH are discussed with reference to the effectiveness of mercaptosuccinic acid, N-acetylpenicillamine, and penicillamine as antidotes for methylmercury poisoning.

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