scholarly journals Sediment classification in a Brazilian reservoir: Pros and cons of parametric low frequencies

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Klajdi Sotiri ◽  
Stephan Hilgert ◽  
Stephan Fuchs
Keyword(s):  
Pulse Length ◽  
Horizontal Resolution ◽  
Acoustic Parameter ◽  
Physical Parameters ◽  
Grab Sampling ◽  
Low Frequencies ◽  
Sediment Classification ◽  
Layering Effect ◽  
Primary Frequency ◽  
Parametric Systems

Sediment is the main factor that limits the reservoir lifetime. Therefore, sediment classification is an essential tool for planning and operating reservoir management measures. There has been important development in the hydroacoustic classification of lakebed, especially with linear systems. The main restrictions while using linear hydroacoustic systems for lakebed classification are the shallow penetration in high-frequency applications or the low vertical and horizontal resolution when using low frequencies. With the new developments in the area of echo sounders, parametric systems can achieve high penetration while preserving the high vertical and lateral resolution. To investigate the performance of parametric systems, a new lakebed classification approach was implemented by using a SES2000 Compact. The area studied was the Passauna reservoir in Parana State, Brazil. We used the first echo division method for processing the acoustic data combined with sediment core and grab sampling. The two physical parameters investigated, were the share of the finest fraction (<63 µm) and wet bulk density (WBD). The results showed a high correlation between the primary frequency of 100 kHz (166 µs pulse length) and the physical parameters. Additionally, a significant correlation was observed with the acoustic parameters at 10 kHz frequency. The best correlating acoustic parameter was Attack/Decay (E1´/E1). The gas presence was found to be an important factor determining the penetration depth of the parametric system and the performance of the classification. The advantages of parametric systems, such small directivity and layering effect, represent the major restrictions in sediment classification applications.

Acoustic parameter estimates and confidence intervals for gravel at low frequencies.

2009 ◽  
Vol 126 (4) ◽  
pp. 2296
Author(s):  
Michael J. White ◽  
George W. Swenson ◽  
Todd A. Borrowman ◽  
George Z. Gertner
Keyword(s):  
Confidence Intervals ◽  
Acoustic Parameter ◽  
Parameter Estimates ◽  
Low Frequencies

STATUS AND TRENDS IN LOGGING

Geophysics ◽  
1970 ◽  
Vol 35 (1) ◽  
pp. 93-112 ◽  
Author(s):  
Hilton B. Evans
Keyword(s):  
Digital Processing ◽  
Acoustic Parameter ◽  
Physical Parameters ◽  
Log Data ◽  
Oil Companies ◽  
Service Companies ◽  
Open Hole ◽  
Multiple Measurements ◽  
Processing Techniques ◽  
Parameters Of Interest

Logging service companies are attempting to provide a fairly good selection of devices which have proven to be popular with the oil industry. However, the introduction of new devices or new services is being limited because oil companies are standardizing the logging‐suites run in their various geographic operating areas. Some of these new techniques appear to have significant applications. Recently, standard logging‐suites and evaluation‐techniques have evolved; these can be evaluated in terms of open‐hole and cased‐hole applications and the physical parameters of interest. Generally, these standard procedures depend on the differences in responses of multiple electrical and porosity devices. The multiple measurements are input to response equations which yield the parameters of interest. Although mining companies have been slow to adopt logging techniques, the use of logging devices and interpretation methods in nonpetroleum mineral (groundwater, nonmetals, metallic sulfides, etc.) exploration and evaluation, and in providing geophysical survey parameters is increasing. Nuclear, electrical, acoustic, and other methods are utilized, and newer applications of these to exploration, particularly in lithology determination, suggest themselves. Log digitizing and computer processing of log data have become routine in most major oil companies, but techniques, programs, and equipment vary significantly. Currently, commercial digitizing services are too expensive to be used extensively; the per‐log costs, however, are declining as more digitizing companies offer competitive services. Two basic commercial systems for transmission and computation of log data are functioning. To date, these systems yield “quicklook” reconnaissance parameter computations. Current research and development emphasis is on pulsed neutron‐spectroscopy and acoustic‐parameter measurements and on digital processing techniques.

scholarly journals Radio Continuum Observations of Large Supernova Remnants

1983 ◽  
Vol 101 ◽  
pp. 377-379
Author(s):  
W. Reich ◽  
E. Fürst ◽  
W. Sieber
Keyword(s):  
Supernova Remnants ◽  
Angular Resolution ◽  
Field Structure ◽  
Radio Continuum ◽  
High Angular Resolution ◽  
Physical Parameters ◽  
Field Orientation ◽  
Low Frequencies ◽  
Magnetic Field Orientation ◽  
Polarization Characteristics

Radio observations of large supernova remnants (SNRs) with high angular resolution have been provided by modern synthesis instruments preferentially at frequencies below 2 GHz. Since these instruments are sensitive mainly to unresolved emission spots, weak extended SNRs usually remain undetected. Besides this, there are numerous physical parameters, which can be studied more properly at higher frequencies. In particular, the polarization characteristics can be more easily analyzed and reduced to the intrinsic magnetic field orientation. In some cases foreground effects substantially disturb the SNR's field structure at low frequencies.

scholarly journals Analysis and discussion of a sample of 25 gigahertz-peaked spectra pulsars

2017 ◽  
Vol 13 (S337) ◽  
pp. 352-353
Author(s):  
Jarosław Kijak ◽  
Wojciech Lewandowski ◽  
Karolina Rożko
Keyword(s):  
Interstellar Medium ◽  
Radio Telescope ◽  
Physical Parameters ◽  
Low Frequencies ◽  
Inverted Spectrum

AbstractWe identified gigahertz-peaked spectra behavior from our radio interferometric observations at low frequencies using the Giant Metrewave Radio Telescope. We modeled the turnover spectra based on thermal free-free absorption in the interstellar medium. The free-free absorption is believed to be responsible for the inverted spectrum. Using the model, we were able to put some observational constrains on the physical parameters of the absorbing matter, which allows us to distinguish between the possible sources of absorption.

scholarly journals Representation of the Denmark Strait Overflow in a z-coordinate eddying configuration of the NEMO (v3.6) ocean model: Resolution and parameter impacts

2020 ◽  
Author(s):  
Pedro Colombo ◽  
Bernard Barnier ◽  
Thierry Penduff ◽  
Jérôme Chanut ◽  
Julie Deshayes ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Vertical Mixing ◽  
Bottom Layer ◽  
Horizontal Resolution ◽  
Ocean Model ◽  
Fixed Number ◽  
Vertical Shear ◽  
Physical Parameters ◽  
Denmark Strait ◽  
The Impact

Abstract. We investigate in this paper the sensitivity of the representation of the Denmark Strait overflow produced by a regional z-coordinate configuration of NEMO (version 3.6) to the horizontal and vertical grid resolutions and to various numerical and physical parameters. Three different horizontal resolutions, 1/12°, 1/36° and 1/60°, are used respectively with 46, 75, 150 and 300 vertical levels. Contrary to expectations, in the given numerical set-up, the increase of the vertical resolution did not bring improvement at eddy-permitting resolution (1/12°). We find a greater dilution of the overflow as the number of vertical level increases, and the worse solution is the one with 300 vertical levels. It is found that when the local slope of the grid is weaker than the slope of the topography the result is a more diluted vein. Such a grid enhances the dilution of the plume in the ambient fluid and produces its thickening. Although the greater number of levels allows for a better resolution of the ageostrophic Ekman flow in the bottom layer, the final result also depends on how the local grid slope matches the topographic slope. We also find that for a fixed number of levels, the representation of the overflow is improved when horizontal resolution is increased to 1/36° and 1/60°, the most drastic improvements being obtained with 150 levels. With such number of vertical levels, the enhanced vertical mixing associated with the step-like representation of the topography remains limited to a thin bottom layer representing a minor portion of the overflow. Two major additional players contribute to the sinking of the overflow, the breaking of the overflow into boluses of dense water which contribute to spread the overflow waters along the Greenland shelf and within the Irminger Basin, and the resolved vertical shear that results from the resolution of the bottom Ekman boundary layer dynamics. This improves the accuracy of the calculation of the entrainment by the turbulent kinetic energy mixing scheme (as it depends on the local shear), and improves the properties of the overflow waters such that they more favorably compare with observations. At 300 vertical levels the dilution is again increased for all horizontal resolutions. The impact on the overflow representation of many other numerical parameters were tested (momentum advection scheme, lateral friction, bottom boundary layer parameterisation, closure parameterisation, etc.) but none had a significant impact on the overflow representation.

scholarly journals Representation of the Denmark Strait overflow in a <i>z</i>-coordinate eddying configuration of the NEMO (v3.6) ocean model: resolution and parameter impacts

2020 ◽  
Vol 13 (7) ◽  
pp. 3347-3371 ◽  
Author(s):  
Pedro Colombo ◽  
Bernard Barnier ◽  
Thierry Penduff ◽  
Jérôme Chanut ◽  
Julie Deshayes ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Vertical Mixing ◽  
Bottom Layer ◽  
Horizontal Resolution ◽  
Ocean Model ◽  
Fixed Number ◽  
Vertical Shear ◽  
Physical Parameters ◽  
Denmark Strait ◽  
The Impact

Abstract. We investigate in this paper the sensitivity of the representation of the Denmark Strait overflow produced by a regional z-coordinate configuration of NEMO (version 3.6) to the horizontal and vertical grid resolutions and to various numerical and physical parameters. Three different horizontal resolutions, 1∕12, 1∕36, and 1/60∘, are respectively used with 46, 75, 150, and 300 vertical levels. In the given numerical set-up, the increase in the vertical resolution did not bring improvement at eddy-permitting resolution (1/12∘). We find a greater dilution of the overflow as the number of vertical level increases, and the worst solution is the one with 300 vertical levels. It is found that when the local slope of the grid is weaker than the slope of the topography the result is a more diluted vein. Such a grid enhances the dilution of the plume in the ambient fluid and produces its thickening. Although the greater number of levels allows for a better resolution of the ageostrophic Ekman flow in the bottom layer, the final result also depends on how the local grid slope matches the topographic slope. We also find that for a fixed number of levels, the representation of the overflow is improved when horizontal resolution is increased to 1∕36 and 1/60∘, with the most drastic improvements being obtained with 150 levels. With such a number of vertical levels, the enhanced vertical mixing associated with the step-like representation of the topography remains limited to a thin bottom layer representing a minor portion of the overflow. Two major additional players contribute to the sinking of the overflow: the breaking of the overflow into boluses of dense water which contribute to spreading the overflow waters along the Greenland shelf and within the Irminger Basin, and the resolved vertical shear that results from the resolution of the bottom Ekman boundary layer dynamics. This improves the accuracy of the calculation of the entrainment by the turbulent kinetic energy mixing scheme (as it depends on the local shear) and improves the properties of the overflow waters such that they more favourably compare with observations. At 300 vertical levels the dilution is again increased for all horizontal resolutions. The impact on the overflow representation of many other numerical parameters was tested (momentum advection scheme, lateral friction, bottom boundary layer parameterization, closure parameterization, etc.), but none had a significant impact on the overflow representation.

scholarly journals Classification of Parkinson Disease Based on Analysis and Synthesis of Voice Signal

2021 ◽  
Vol 16 (4) ◽  
pp. 1-22
Author(s):  
Vikas Mittal ◽  
R. K. Sharma
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Vocal Tract ◽  
Acoustic Parameter ◽  
Physical Parameters ◽  
Voice Signal ◽  
Analysis And Synthesis ◽  
The Central Nervous System ◽  
Pitch Ratio

The most important application of voice profiling is pathological voice detection. Parkinson's disease is a chronic neurological degenerative disease affecting the central nervous system responsible for essentially progressive evolution movement disorders. 70% to 90% of Parkinson’s disease (PD) patients show an affected voice. This paper proposes a methodology for PD based on acoustic, glottal, physical, and electrical parameters. The results show that the acoustic parameter is more important in the case of Parkinson’s disease as compared to glottal and physical parameters. The authors achieved 97.2% accuracy to differentiate Parkinson and healthy voice using jitter to pitch ratio proposed algorithm. The Authors also proposed an algorithm of poles calculation of the vocal tract to find formants of the vocal tract. Further, formants are used for finding the transfer function of vocal tract filter. In the end, the authors suggested parameters of the electrical vocal tract model are also changed in the case of PD voices.

Are melting alpine glaciers a source of legacy priority contaminants to downstream environments? A high-frequency analysis of water chemistry in the Canadian Rockies.

2020 ◽  
Author(s):  
Kasia Staniszewska ◽  
Colin Cooke ◽  
Alberto Reyes
Keyword(s):  
Trace Elements ◽  
Water Chemistry ◽  
High Frequency ◽  
High Temporal Resolution ◽  
Physical Parameters ◽  
Flow Conditions ◽  
Grab Sampling ◽  
Element Concentrations ◽  
Group A ◽  
Group B

&lt;p&gt;Glaciers are retreating across the Canadian Cordillera. As this ice melts trace elements and other contaminants, accumulated from millennia of atmospheric deposition, are subject to release with uncertain consequences for downstream water quality. It is therefore imperative to constrain the rate and magnitude of contaminant input to river systems from glacierized watersheds. Meltwater chemistry was monitored and modelled at a high temporal frequency using a combination of grab-sampling and sondes for physical, chemical, and hydrological parameters at the outlet of proglacial Sunwapta Lake, Athabasca Glacier, Canada. Principal component analysis revealed that chemical parameters could be split into two groups with distinct seasonal trends. Group A encompasses solutes and endogenic bedrock weathering associated elements. Group B includes particulate, and exogenic dust-associated elements. Group A element concentrations were highest during low flow conditions and were correlated positively with conductivity. Group B element concentrations were highest during high flow conditions and had a moderate positive correlation with turbidity. Concentrations of potentially hazardous trace elements remained below Canadian Environmental Quality Guidelines throughout the hydrological season (THg &lt; 2.7 ng/L; TPb &lt; 1.7 &amp;#181;g/L; TAs &lt; 0.34 &amp;#181;g/L; TCr &lt; 1.9 &amp;#181;g/L). Trace element fluxes (kg/year) and yields (kg/year/watershed area) were modelled at a high temporal-resolution by pairing grab sampling results with corresponding strongly correlated high-frequency physical parameters: conductivity or turbidity. Annual fluxes and yields were comparable or lower than fluxes and yields from other glacial meltwater streams globally. Annual fluxes and yields were THg: 95 kg/yr &amp;#160;and 3.2 g/yr/km&lt;sup&gt;2&lt;/sup&gt;; TPb: 34 kg/yr and 1.2 kg/yr/km&lt;sup&gt;2&lt;/sup&gt;; TCr 39.5 kg/yr and 1.4 kg/yr/km&lt;sup&gt;2&lt;/sup&gt;; TAs: 7.3 kg/yr and 0.25 kg/yr/km&lt;sup&gt;2&lt;/sup&gt;. Numerous studies have suggested that glaciers are a significant source of high concentrations, fluxes, and yields of contaminants, including: pesticides; PAHs; PCBs; and toxic trace elements. In contrast, we found low concentrations, fluxes, and yields of trace elements in meltwater from the rapidly retreating Athabasca Glacier. Grab-sampling complemented by high-frequency monitoring of physical and chemical water parameters allowed a high-resolution view of water chemistry variation in meltwater from the Athabasca Glacier.&lt;/p&gt;

SOME ELECTROMECHANICAL METHODS FOR PRODUCING LOW FREQUENCIES FROM A PRIMARY FREQUENCY STANDARD

1949 ◽  
Vol 27f (2) ◽  
pp. 49-54 ◽  
Author(s):  
D. W. R. McKinley
Keyword(s):  
High Stability ◽  
Quartz Crystal ◽  
Primary Standard ◽  
Frequency Standard ◽  
Low Frequencies ◽  
Primary Frequency

Minor mechanical modifications to the clock motor of a quartz crystal primary standard of frequency simplify the problem of producing accurate low frequencies. Electromechanical gate circuits are used to provide pulses of high stability at repetition rates of 1, 10, 100, and 1000 pulses per second for stroboscopic and other applications.

Some Results of the Spectroscopic Study of Four Close Binary Systems of Early Spectral Types

1965 ◽  
Vol 5 ◽  
pp. 120-130
Author(s):  
T. S. Galkina
Keyword(s):  
Spectroscopic Study ◽  
Spectral Type ◽  
Spectroscopic Investigation ◽  
Binary Systems ◽  
Quantitative Information ◽  
Close Binary ◽  
Physical Parameters ◽  
Absorption And Emission ◽  
Close Binary Systems ◽  
Quantitative Estimates

It is necessary to have quantitative estimates of the intensity of lines (both absorption and emission) to obtain the physical parameters of the atmosphere of components.Some years ago at the Crimean observatory we began the spectroscopic investigation of close binary systems of the early spectral type with components WR, Of, O, B to try and obtain more quantitative information from the study of the spectra of the components.

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