scholarly journals ON THE ACOUSTO-MAGNETIC METHOD OF MEASURING THE ACOUSTIC RESISTANCE OF LOCAL AREAS OF THE BIOLOGICAL TISSUE

2021 ◽  
pp. 72-79
Author(s):  
Igor Bondarenko ◽  
Oleg Avrunin
Keyword(s):  
Magnetic Field ◽  
Biological Tissue ◽  
Acoustic Radiation ◽  
Radiation Power ◽  
Local Area ◽  
Magnetic Method ◽  
Electric Voltage ◽  
Local Areas ◽  
Acoustic Resistance

The subject of study in the article is the acoustic resistance of local areas of the biological tissues in vivo, depending on their pathology. The aim of the work is to develop a quantitative method for measuring the acoustic resistance of local areas of the biological tissue (substance) located inside the human body. The following tasks are solved in the article: development of scientific foundations of the acousto-magnetic method for measuring the acoustic resistance of local areas of the biological tissue; development of a remote method for measuring electrical voltage on the surface of the patient's skin, caused by acousto-magnetic impact on local areas of the tissue and determined by the value of acoustic resistance; calculation of the ratios binding the value of the acoustic resistance of the local areas of the tissue with the electric voltage on the measuring probes on the patient's skin, the values of the acoustic radiation power and the external constant magnetic field, as well as with the distance between the probes and the local area of the biological tissue; verification of the calculated ratios using the experimental determination of the acoustic resistance of the local area of the model biological tissue. The following methods were used: physical modeling of the biological tissue, physical and mathematical modeling of electrical properties of the local part of the biological tissue, calculation of electromagnetic and acoustic parameters of the tissue, experimental measurement of electric field strength excited in the local part of the biological tissue, verification of calculated relations by comparing them with experimental results. The following results were obtained: the scientific foundations of the acousto-magnetic method for the quantitative measurement of the acoustic resistance of local areas of the biological tissue were developed; a remote method for measuring the electric voltage on the surface of the patient's skin caused by the acousto-magnetic effect on local areas of the tissue and the determined value of the acoustic impedance was developed; relations were calculated connecting the value of the acoustic impedance of local areas of the tissue with the electric voltage on the measuring probes on the patient's skin, the values of the acoustic radiation power and external constant magnetic field, as well as the distance between the probes and the local area of the biological tissue; verification of the calculated ratios was carried out using the experimental determination of the acoustic resistance of the local area of the model biological tissue. Conclusions: The scientific foundations of the remote acousto-magnetic method of high-precision measurement of the acoustic resistance of local areas of human biological tissue, confirmed experimentally on model tissue samples, have been developed. The method can make it possible to reveal with high accuracy the functional relations of the measured local value of acoustic resistance with pathological changes in the tissue. At the same time, the influence of the human factor on the interpretation of the recorded values of acoustic resistance (which is characteristic of the traditional, mainly qualitative, rather than quantitative ultrasound method) is excluded, the information content and reliability of acoustic diagnostics are increased.

Формирование изображений электрических сигналов преобразователя магнитного поля при гистерезисной интерференции для контроля металлов в импульсных магнитных полях

2020 ◽  
pp. 38-45
Author(s):  
В.В. Павлюченко ◽  
Е.С. Дорошевич
Keyword(s):  
Magnetic Field ◽  
Aluminum Plate ◽  
Thickness Variation ◽  
Magnetic Carrier ◽  
Electric Voltage ◽  
Total Strength ◽  
Magnetic Field Transducer ◽  
The Given ◽  
The Magnetic Field

Based on the developed methods of hysteresis interference, the calculated dependences U(x) of the electric voltage taken from the magnetic field transducer on the x coordinate were obtained. A magnetic carrier with an arctangent characteristic was exposed to a series of bipolar pulses of the magnetic field of a linear inductor of one, two, three, four, five and fifteen pulses. An algorithm is presented for the sequence of changes in the magnitude of the total strength of the magnetic field pulses on the surface of an aluminum plate, which provides the same amplitude of hysteresis oscillations of the electric voltage and makes it possible to obtain a linear difference dependence U(x) for wedge-shaped and flat aluminum samples. The results obtained make it possible to increase the accuracy and efficiency of control of the thickness of the object and its thickness variation in the given directions, as well as the defects of the object.

scholarly journals Determination of the hyperfine magnetic field in magnetic carbon-based materials: DFT calculations and NMR experiments

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Jair C. C. Freitas ◽  
Wanderlã L. Scopel ◽  
Wendel S. Paz ◽  
Leandro V. Bernardes ◽  
Francisco E. Cunha-Filho ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Dft Calculations ◽  
Hyperfine Magnetic Field ◽  
Magnetic Carbon ◽  
Carbon Based

STUDY OF THE TEXTURING IN BSCCO-AG TAPES THROUGH MAGNETIC MEASUREMENTS

2000 ◽  
Vol 14 (25n27) ◽  
pp. 3159-3164
Author(s):  
C. FERDEGHINI ◽  
M. R. CIMBERLE ◽  
G. GRASSO ◽  
P. GUASCONI ◽  
A. MALAGOLI ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Magnetic Measurements ◽  
Texture Evolution ◽  
Rolling Direction ◽  
Longitudinal Direction ◽  
Magnetic Method ◽  
Superconducting Compounds

We have developed a method that allows, by a simple set of magnetic measurements, to study the texturing of the grains inside a BSCCO-Ag tape. Because the texture is anisotropic we define the angle ϑ L that identifies the mean grain misalignment angle with respect to the tape surface in longitudinal direction (i.e. rolling direction) and the angle ϑ T in transverse direction. The technique is based on the assumption that, because of the very high anisotropy of the critical current density in BSCCO superconducting compounds, the magnetic moment is essentially generated by the current circulating in the a-b planes of the BSCCO grains. The different magnetisation cycles, measured when the orientation of the magnetic field with respect to the tape surface is changed, depend only on the grain orientation inside the tape, which determines the effective magnetic field component normal to the a-b planes of the grains. Here we present the texture evolution of the BSCCO grains inside silver sheated multifilamentary tape starting from the initial steps of the mechanical deformation up to the final heating stage. The results obtained from the magnetic method are compared with those obtained with other methods, i.e. X-ray diffraction and critical current density anisotropy. Also results obtained on samples prepared in different way will be presented.

Calculation and Verification of Magnetic Field Parameters in Axial Active Magnetic Bearing

2014 ◽  
Vol 214 ◽  
pp. 143-150
Author(s):  
Piotr Graca
Keyword(s):  
Magnetic Field ◽  
Finite Element Method ◽  
Magnetic Force ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Magnetic Flux Density ◽  
Two Dimensional ◽  
The Finite Element Method ◽  
Magnetic Field Computation

The paper presents numerical modeling of an Axial Active Magnetic Bearing (AAMB) based on two-dimensional (2D) magnetic field computation. The calculations, assisted by the Finite Element Method (FEM), have focused on the determination of the magnetic flux density and the magnetic force. Obtained magnetic field parameters were then measured and verified on a physical model.

Determination of magnetic field strengths in radio stellar binaries by VLBI observations

2008 ◽  
pp. 135-138 ◽  
Author(s):  
Jean-Francois Lestrade ◽  
Robert L. Mutel ◽  
Robert A. Preston ◽  
Robert B. Phillips
Keyword(s):  
Magnetic Field ◽  
Vlbi Observations ◽  
Field Strengths
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