scholarly journals Inference of biological and physical parameters in an internal wave using multiple-frequency, acoustic-scattering data

2003 ◽  
Vol 60 (5) ◽  
pp. 1033-1046 ◽  
Author(s):  
Joseph D. Warren ◽  
Timothy K. Stanton ◽  
Peter H. Wiebe ◽  
Harvey E. Seim
Keyword(s):  
Internal Wave ◽  
Field Experiments ◽  
Gulf Of Maine ◽  
Acoustic Scattering ◽  
Primary Source ◽  
Theoretical Work ◽  
Scattering Data ◽  
Physical Parameters ◽  
Multiple Frequency ◽  
Scattering Spectra

Abstract High-frequency sound (>10 kHz) is scattered in the ocean by many different processes. In the water column, marine organisms are often assumed to be the primary source of acoustic backscatter. Recent field experiments and theoretical work suggest that the temperature and salinity microstructure in some oceanic regions could cause acoustic scattering at levels comparable to that caused by marine life. Theoretical acoustic-scattering models predict that the scattering spectra for microstructure and organisms are distinguishable from each other over certain frequency ranges. A method that uses multiple-frequency acoustic data to exploit these differences has been developed, making it possible to discriminate between biological and physical sources of scattering under some conditions. This method has been applied to data collected in an internal wave in the Gulf of Maine. For regions of the internal wave in which the dominant source of scattering is either biological or physical in origin, it is possible to combine the acoustic-scattering data and temperature and salinity profiles with acoustic-scattering models to perform a least-squares inversion. Using this approach, it is possible to estimate the dissipation rate of turbulent kinetic energy for some regions of the internal wave, and the length and numerical abundance of the dominant biological scatterer, euphausiids, in others.

The study of acoustic scattering from a single sound-permeable sphere

2018 ◽  
Vol 13 (4) ◽  
pp. 79-91 ◽  
Author(s):  
E.Sh. Nasibullaeva
Keyword(s):  
Speed Of Sound ◽  
Numerical Technique ◽  
Acoustic Scattering ◽  
Computer Time ◽  
Physical Parameters ◽  
Fast Method ◽  
Scattering Field ◽  
Permeable Sphere ◽  
Test Verification ◽  
Good Agreement

The paper presents a generalized mathematical model and numerical investigation of the problem of acoustic scattering from a single sound-permeable sphere during the passage of two types of waves - spherical from a monopole radiation source and a plane one. In solving the Helmholtz equation, a numerical technique based on the fast method of multipoles is used, which allows achieving high accuracy of the results obtained at the lowest cost of computer time. The calculations are compared with known experimental data and a good agreement is obtained. The formulas for calculating the main characteristic of the scattering field (the total scattering cross section) for a sound-permeable sphere are generalized. The effect on this characteristic of the physical parameters of media outside and inside the sphere, such as the density and speed of sound, is shown. A numerical parametric analysis of the pressure distribution around a single sound-permeable sphere for different values of the wave radius, density, and speed of sound of the outer and inner medium of the sphere is carried out. The obtained results will later be used for test verification calculations for the numerical solution of the generalized problem of acoustic scattering of a set of sound-permeable spheres (coaxial or arbitrarily located in space).

scholarly journals Simulation and Experimental Study of the Near Field Probe in the Form of a Folded Dipole for Measuring Glucose Concentration

2021 ◽  
Vol 11 (12) ◽  
pp. 5415
Author(s):  
Aleksandr Gorst ◽  
Kseniya Zavyalova ◽  
Aleksandr Mironchev ◽  
Andrey Zapasnoy ◽  
Andrey Klokov
Keyword(s):  
Experimental Measurement ◽  
Glucose Concentration ◽  
Field Experiments ◽  
Near Field ◽  
Vector Network Analyzer ◽  
Human Hand ◽  
Physical Parameters ◽  
Network Analyzer ◽  
Frequency Range ◽  
Average Deviation

The article investigates the near-field probe of a special design to account for changes in glucose concentration. The probe is designed in such a way that it emits radiation in both directions from its plane. In this paper, it was proposed to modernize this design and consider the unidirectional emission of the probe in order to maximize the signal and reduce energy loss. We have done extensive research for both bidirectional and unidirectional probe designs. Numerical simulations and field experiments were carried out to determine different concentrations of glucose (0, 4, 5.3, 7.5 mmol/L). Numerical modeling of a unidirectional probe showed that the interaction of radiation generated by such a probe with a multilayer structure simulating a human hand showed a better result and high sensitivity compared to a bidirectional probe. Further, based on the simulation results, a phantom (physical model) of a human hand was recreated from layers with dielectric properties as close as possible to the properties of materials during simulation. The probe was constructed from a copper tube and matched both the geometric and physical parameters of the model. The experimental measurement was carried out using a vector network analyzer in the frequency range 2–10 GHz. The experimental measurement was carried out using a vector network analyzer in the frequency range 2–10 GHz for the unidirectional and bidirectional probes. Further, the results of the experiment were compared with the results of numerical simulation. According to the results of multiple experiments, it was found that the average deviation between the concentrations was 2 dB for a unidirectional probe and 0.4 dB for a bidirectional probe. Thus, the sensitivity of the unidirectional probe was 1.5 dB/(mmol/L) for the bidirectional one 0.3 dB/(mmol/L). Thus, the improved design of the near-field probe can be used to record glucose concentrations.

scholarly journals Comparison of the Initial Growth of Different Poplar Clones on Four Sites in Western Slovakia—Preliminary Results

2021 ◽  
Author(s):  
Dávid Heilig ◽  
Bálint Heil ◽  
Christoph Leibing ◽  
Heinz Röhle ◽  
Gábor Kovács
Keyword(s):  
Hybrid Poplar ◽  
Aridity Index ◽  
Primary Source ◽  
Nutrient Status ◽  
Physical Parameters ◽  
Initial Growth ◽  
Key Factors ◽  
Groundwater Availability ◽  
Secondary Sources ◽  
Short Rotation

AbstractThis study was conducted to evaluate four hybrid poplar comparison tests along a groundwater availability gradient in Western Slovakia. The weather fluctuation during the 3-year study period was described with indices, such as the Forestry Aridity Index (FAI) or the hydrothermal coefficient (HTC). The soil chemical and physical parameters were determined from soil samples from the two upper horizons. The nutrient status and supply of the trees were categorized based on leaf elemental analysis. Altogether, 21 different clones from 6 genomic groups were compared. The survival (SRV), diameter at breast height (DBH), and height of the trees (H) had been measured annually since the plantations were established, and from these measurements, mean annual height increment (MAHI) values were derived. These weather, edaphic, and clonal factors were evaluated and compared. Significant effects of the site (edaphic factors) were found as the primary source of variance and clonal differences as secondary sources of variance among the growth of trees. The interaction of site × clone effects was not significant. The results showed that for short rotation forestry (SRF), the site parameters—especially groundwater availability—are key factors.

Thermodynamics of James Watt – Ignored or not Understood?

2021 ◽  
Vol 42 (3) ◽  
pp. 397
Author(s):  
Jovan Mitrovic
Keyword(s):  
Latent Heat ◽  
Heat Engine ◽  
Primary Source ◽  
Rankine Cycle ◽  
Theoretical Work ◽  
Steam Pressure ◽  
Steam Engine ◽  
Saturated Steam ◽  
Maximum Efficiency ◽  
Starting Point

In the analysis of the development of thermodynamics as a science, the theoretical work of Sadi Carnot, published in 1824, is generally considered to be the starting point. Carnot studied the cycle of an ideal heat engine and formulated the condition for its maximum efficiency. In this article we examine James Watt’s contributions to the formation of fundamental concepts of thermodynamics, made in the course of his work on improving the Newcomen engine and developing his own steam engine. It is shown that Watt was the first to characterize thermodynamic properties such as latent heat and vapor density. The authors prove Watt’s priority in the studies of the dependence of saturated steam pressure on temperature, in which a critical point was found when the latent heat disappears. These results of Watt anticipated by many decades the studies on the thermodynamic critical state by Th. Andrews and J. Thomson. The article also discusses Wattʼs research on thermodynamic cycles. It is shown that he was the first to study the Rankine cycle with superheated steam, known from the history of thermodynamics. Watt was also the first scientist to introduce the concept of a steam engine’ volumetric work as the product of pressure and volume, and developed a device, the steam pressure indicator, to measure its value. We show the results obtained by Watt with steam to be considerably ahead of Prescott Jouleʼs work on the cooling and condensation of gases during expansion. The article presents an interpretation of Watt’s 1769 patent that is very important as the primary source for a subsequent study and establishment of the principles of energy conversion. The factual material presented in this article suggests that Watt’s scientific research have not been properly understood or simply went unnoticed.

scholarly journals Towards Identification of Optimum Radar Parameters for Sea-Ice Monitoring

1985 ◽  
Vol 31 (109) ◽  
pp. 214-219
Author(s):  
Y. S. Kim ◽  
R. K. Moore ◽  
R. G. Onstott ◽  
S. Gogineni
Keyword(s):  
Sea Ice ◽  
Field Experiments ◽  
Theoretical Models ◽  
First Year ◽  
Physical Parameters ◽  
Backscattering Coefficient ◽  
Air Bubble ◽  
X Band ◽  
Experimental Findings ◽  
Range Of Values

AbstractVarious field experiments have shown that microwave radars can be used to distinguish multi-year from first-year ice, although optimum radar parameters are not yet fully defined.This paper presents the results from two theoretical models that, using selected physical parameters of sea ice, are able to predict the backscattering from multi-year and first-year ice under cold conditions. The possible ranges of the backscattering coefficient under various conditions (surface roughness, salinity, temperature, density, and air-bubble size) are calculated for multi-year and first-year ice by adjusting the parameters within the reported range of values.Although the calculations show no specific resonance that would favor any particular frequency or incidence angles, the results confirm the experimental findings that Ku- and X-band frequencies, and incidence angles greater than 30°, are better for distinguishing sea-ice types than lower frequencies.

Acoustic scattering and inverse problem: determination of physical parameters of a multilayered structure

1991 ◽  
Vol 7 (3) ◽  
pp. 369-378 ◽  
Author(s):  
O Lenoir ◽  
J L Izbicki ◽  
P Rembert ◽  
G Maze ◽  
J Ripoche
Keyword(s):  
Inverse Problem ◽  
Acoustic Scattering ◽  
Multilayered Structure ◽  
Physical Parameters

A Novel Classification Method of Fish Based on Multi-Feature Fusion

2015 ◽  
Vol 713-715 ◽  
pp. 1513-1519 ◽  
Author(s):  
Wei Dong Du ◽  
Bao Wei Chen ◽  
Hai Sen Li ◽  
Chao Xu
Keyword(s):  
Discrete Cosine Transform ◽  
Feature Fusion ◽  
Acoustic Scattering ◽  
Scattering Data ◽  
Support Vector ◽  
Svm Classifier ◽  
Correct Identification ◽  
Classification Problems ◽  
Cosine Transform ◽  
Identification Rate

In order to solve fish classification problems based on acoustic scattering data, temporal centroid (TC) features and discrete cosine transform (DCT) coefficients features used to analyze acoustic scattering characteristics of fish from different aspects are extracted. The extracted features of fish are reduced in dimension and fused, and support vector machine (SVM) classifier is used to classify and identify the fishes. Three kinds of different fishes are selected as research objects in this paper, the correct identification rates are given based on temporal centroid features and discrete cosine transform coefficients features and fused features. The processing results of actual experimental data show that multi-feature fusion method can improve the identification rate at about 5% effectively.

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