Comparing two 38-kHz scientific echosounders

Abstract The EK500 has been the state-of-the-art scientific echosounder for surveying marine fish stocks for over a decade; the EK60 is its successor. Ensuring comparability in performance is vital during the transition from the EK500 to the EK60. To quantify the respective performances, each echosounder was calibrated in tandem by the standard-target method using the same 38-kHz, 12° beam width, split-beam transducer, with alternating pinging by means of an external triggering-and-switching system. The principal measurements comprised split-beam-determined angle and target strength, on-axis sensitivity, and directionality in the plane normal to the acoustic axis, as measured with a 60-mm-diameter copper sphere. Ambient noise, including volumetric reverberation, was also measured. Principal comparisons included those of the time-series and histograms of split-beam-determined target strength; respective alongship and athwartship angles as determined by the split-beam system; and as expected, difference in the split-beam-determined and experimental target-strength values in the plane normal to the acoustic axis. The mean absolute difference in off-axis angle values was also compared. While the performance of the two echosounders is generally similar, systematic differences exist. For the particular calibration measurements, the time variability in measurements of on-axis target strength was of the order of 1 dB for the EK500 and 2 dB for the EK60. The target-strength distribution for measurements made with the EK500 was normal, with standard deviation 0.2–0.3 dB, whereas for the EK60, the target-strength distribution was distinctly skewed and the standard deviation varied over 0.3–0.5 dB. Differences were found between the split-beam and physical-angle measurements. They were noticeably larger in the case of the EK60. Differences in performance between the two echosounders suggest refinements to the new system that will help realize its full potential in scientific work.

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Association of Long-Term Change and Variability in Glycemia with Risk of Incident Heart Failure among Patients with Type 2 Diabetes Mellitus – A Secondary Analysis of the ACCORD Trial

10.2337/figshare.12273155.v2 ◽

2020 ◽

Author(s):

Matthew W. Segar ◽

Kershaw V. Patel ◽

Muthiah Vaduganathan ◽

Melissa C. Caughey ◽

Javed Butler ◽

...

Keyword(s):

Standard Deviation ◽

Secondary Analysis ◽

Glycemic Variability ◽

Baseline Risk ◽

Absolute Difference ◽

Cox Models ◽

Term Change ◽

Alternative Measures

Objective: Evaluate the associations between long-term change and variability in glycemia with risk of HF among patients with T2DM. Research Design and Methods: Among participants with T2DM enrolled in the ACCORD trial, variability in HbA1c was assessed from stabilization of HbA1c following enrollment (8 months) to 3 years of follow-up as follows: average successive variability (ASV=average absolute difference between successive values), coefficient of variation (CV=standard deviation/mean), and standard deviation. Participants with HF at baseline or within 3 years of enrollment were excluded. Adjusted Cox models were used to evaluate the association of % change (from baseline to 3 years of follow-up) and variability in HbA1c over the first 3 years of enrollment and subsequent risk of HF. Results: The study included 8,576 patients. Over a median follow-up of 6.4 years from the end of variability measurements at year 3, 388 patients had an incident HF hospitalization. Substantial changes in HbA1c were significantly associated with higher risk of HF [HR (95% CI) for ≥10% decrease = 1.32 (1.08-1.75), ≥10% increase = 1.55 (1.19-2.04), ref: <10% change in HbA1c]. Higher long-term variability in HbA1c was significantly associated with higher risk of HF [HR (95% CI) per 1 SD of ASV = 1.34 (1.17-1.54)] independent of baseline risk factors and interval changes in cardiometabolic parameters. Consistent patterns of association were observed using alternative measures of glycemic variability. Conclusions: Substantial long-term changes and variability in HbA1c were independently associated with risk of HF among patients with T2DM.

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Validation of satellite OPEMW precipitation product with ground-based weather radar and rain gauge networks

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-6-4279-2013 ◽

2013 ◽

Vol 6 (3) ◽

pp. 4279-4312 ◽

Cited By ~ 1

Author(s):

D. Cimini ◽

F. Romano ◽

E. Ricciardelli ◽

F. Di Paola ◽

M. Viggiano ◽

...

Keyword(s):

Standard Deviation ◽

Winter Season ◽

National Research Council ◽

Residual Effect ◽

Temporal Analysis ◽

Mean Difference ◽

Absolute Difference ◽

Data Set ◽

Rain Gauges ◽

Weather Radars

Abstract. The Precipitation Estimation at Microwave Frequencies (PEMW) algorithm was developed at the Institute of Methodologies for Environmental Analysis of the National Research Council of Italy (IMAA-CNR) for inferring surface rain intensity (sri) from satellite passive microwave observations in the range from 89 to 190 GHz. The operational version of PEMW (OPEMW) has been running continuously at IMAA-CNR for two years, producing sri estimates feeding an operational hydrological model for forecasting flood alerts. This paper presents the validation of OPEMW against simultaneous ground-based observations obtained by a network of 20 weather radars and a network of more than 3000 rain gauges distributed over the Italian peninsula and main islands. The validation effort uses a data set spanning a one-year period (July 2011–June 2012). The effort evaluates dichotomous and continuous scores for the assessment of rain detection and quantitative estimate, respectively, investigating both spatial and temporal features. The analysis demonstrates 98% accuracy in correctly identifying rainy and non-rainy areas, and it quantifies the increased ability (with respect to random chance) to detect rainy and non-rainy areas (0.42–0.45 Heidke skill score) or rainy areas only (0.27–0.29 equitable threat score). Performances are better than average during summer, fall, and spring, while worse than average in the winter season. The spatial-temporal analysis does not show seasonal dependence except for larger mean absolute difference over the Alps and northern Apennines during winter, attributable to residual effect of snow cover. A binned analysis in the 0–15 mm h−1 range suggests that OPEMW tends to slightly overestimate sri values below 6–7 mm h−1, and to underestimate sri above those values. Depending upon the ground reference (either rain gauges or weather radars), the mean difference is 0.8–2.8 mm h−1, with a standard deviation within 2.6–3.1 mm h−1 and correlation coefficient within 0.8–0.9. The monthly mean difference was shown to remain within ±1 mm h−1 with respect to rain gauges and within −2 mm h−1 with respect to weather radars, with 2–4 mm h−1 standard deviation.

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Research on the Passive Detection Model Based on 3D-HBF and FSVDD for Underwater High-Speed Small Targets and its Application

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.317-319.1282 ◽

2011 ◽

Vol 317-319 ◽

pp. 1282-1288

Author(s):

Qiao Hu ◽

Bao An Hao ◽

Hong Yi ◽

Yun Chuan Yang

Keyword(s):

Target Detection ◽

High Speed ◽

Beam Width ◽

Target Strength ◽

Support Vector ◽

Support Vector Data Description ◽

Passive Detection ◽

Detection Model ◽

Model Based ◽

Small Targets

Due to the high-speed, short-time countermeasure and small target strength of underwater high-speed small targets (UHSST), it is difficult to use a traditional method to accurately detect UHSST. So a novel passive detection model based on three-dimensional hyperbeam forming (3D-HBF) and fuzzy support vector data description (FSVDD) is proposed, where these advantages of beam width reduction and side lobe suppression for 3D-HBF and excellent target-detection capability for FSVDD are combined. The model consists of two stages. In the first stage, 3D-HBF is carried out to obtain the beam respond vectors (BSV) from original underwater acoustic signals. In the second stage, the BSV are input into the detector based on FSVDD to detect and locate the underwater targets intelligently. This model is applied to target detection of UHSST, and these testing results show that the proposed model has better detection performance than the conventional beam forming method, with a high detection success rate and localization capability.

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Acoustic Measurement of Fish Schools Using Array Phase Information

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f87-186 ◽

1987 ◽

Vol 44 (9) ◽

pp. 1544-1550 ◽

Cited By ~ 5

Author(s):

G. L. Thomas ◽

Darrell R. Jackson

Keyword(s):

Horizontal Plane ◽

Beam Width ◽

Target Strength ◽

Acoustic Measurement ◽

Phase Information ◽

Fish Schools ◽

Fish School ◽

Blue Whiting ◽

Beam Directivity ◽

Better Than

Array phase information on the azimuth and elevation of fish schools allows for beam directivity corrections of target strength, determinations of school depth, and tracking of school movements. When corrected for beam pattern losses, the target strength of blue whiting (Micromesistious poutassou) and rockfish (Sebastes spp.) schools increased approximately 3 dB. The vertical placement of fish schools with the side-scanning split-beam sonar agreed with the fish school depths observed with an echosounder. Split-beam phase was used to track blue whiting schools in the horizontal plane with azimuthal accuracy considerably better than the 3-dB beam width (approximately 20°).

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Acoustical Assessment of Squid (Loligo opalescens) off the Central Oregon Coast

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f87-149 ◽

1987 ◽

Vol 44 (6) ◽

pp. 1261-1267 ◽

Cited By ~ 19

Author(s):

Katharine Jefferts ◽

Janusz Burczynski ◽

William G. Pearcy

Keyword(s):

Geographic Distribution ◽

Distribution Density ◽

Strength Distribution ◽

Target Strength ◽

Adjacent Area ◽

Density Estimates ◽

Oregon Coast ◽

Loligo Opalescens ◽

Dual Beam

Squid (Loligo opalescens) were surveyed acoustically in an area off the Oregon coast using dual-beam and echo integrator techniques. The method developed is shown to be feasible for in situ estimation of target strength, distribution, and abundance of midwater squids. Average target strength was estimated both while drifting with a squid school and cruising over one. The values derived, −58.6 to −58.7 dB, are much lower than previous estimates, but more realistic in relation to the target strength of fishes. Schools judged to be fish or squid showed little difference in depth or size, but varied significantly in geographic distribution. Density estimates ranged from 9.9 t/km2 in a known spawning area to 0.93 t/km2 in an adjacent area.

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Association of Long-Term Change and Variability in Glycemia with Risk of Incident Heart Failure among Patients with Type 2 Diabetes Mellitus – A Secondary Analysis of the ACCORD Trial

10.2337/figshare.12273155 ◽

2020 ◽

Author(s):

Matthew W. Segar ◽

Kershaw V. Patel ◽

Muthiah Vaduganathan ◽

Melissa C. Caughey ◽

Javed Butler ◽

...

Keyword(s):

Standard Deviation ◽

Secondary Analysis ◽

Glycemic Variability ◽

Baseline Risk ◽

Absolute Difference ◽

Cox Models ◽

Term Change ◽

Alternative Measures

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Comparing Fish Density and Echo Strength Distribution Recorded by Two Generations of Single Beam Echo Sounders

Applied Sciences ◽

10.3390/app9102041 ◽

2019 ◽

Vol 9 (10) ◽

pp. 2041 ◽

Cited By ~ 2

Author(s):

Arne N. Linløkken ◽

Frode Næstad ◽

Kjell Langdal ◽

Kjartan Østbye

Keyword(s):

Salvelinus Alpinus ◽

Arctic Charr ◽

Strength Distribution ◽

Target Strength ◽

Fish Density ◽

Fish Stock ◽

Coregonus Lavaretus ◽

Total Density ◽

Single Beam ◽

Two Generations

Hydroacoustic acquisition was performed by means of two different single beam systems, the Simradmodel EK15 from 2015 and the Simrad model EY-M from the 1980s to explore potential differences of fish density and target strength (TS) distribution between EK15 and EY-M-based estimates. The oligotrophic Lake Storsjøen (48 km2) with steep shores, was chosen for the survey. The pelagic fish stock is dominated by whitefish (Coregonus lavaretus L.), and, recently, illegally stocked smelt (Osmerus eperlanus L.), and a low proportion of Arctic charr (Salvelinus alpinus L.). The total density was estimated at two depth layers (18–32 and 32–48 m), and was quite similar for TS ≥ −56 dB: 755 and 498 fish ha−1, respectively for the EK15-based estimates and similarly 766 and 490 fish ha−1 for the EY-M estimate. Target strength distributions were similar for TS > −48 dB. The proportion of single fish detected with EK15 was negatively affected by the long pulse duration. Six acquisitions from 1986 to 2016 showed a dramatic increase of density of TS = −46 to −44 dB echoes (>10 cm) between 2013 and 2016. This was due to the growth of the introduced smelt population.

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Analysis of Echo Counting Data: A Model

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f84-054 ◽

1984 ◽

Vol 41 (3) ◽

pp. 451-458 ◽

Cited By ~ 21

Author(s):

R. Kieser ◽

T. J. Mulligan

Keyword(s):

Strength Distribution ◽

Range Limits ◽

Target Strength ◽

Density Estimates ◽

Correct Model ◽

Counting Data ◽

Chart Recorder ◽

Standard Tool ◽

Echo Pulse ◽

Counting Model

Echo counting is a standard tool for the estimation of fish density and hence population. Density estimates are readily obtained using an uncalibrated, stable echo sounder with accurate time-varied gain. We extended a standard nonstochastic echo pulse counting model to include the analysis of single fish echo traces as they are obtained from the sounder chart recorder. The trace counting analysis depends strongly on the overlap in the insonified volumes between successive sounder transmissions. An equation for the nonoverlapping volume is given in terms of range, distance between transmissions, and effective beam angles. The near and far range limits of the model are given and the errors associated with the commonly used approximations to the correct model are shown. A generalization of the model considers the analysis of data from a tilted transducer. A sensitivity analysis gives a qualitative indication of the model's performance for echoes from fish with a realistic target strength distribution. Single fish echo returns are analyzed by the echo pulse and trace counting methods to illustrate the model.

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Diel patterns in pelagic fish behaviour and distribution observed from a stationary, bottom-mounted, and upward-facing transducer

ICES Journal of Marine Science ◽

10.1016/j.icesjms.2004.07.006 ◽

2004 ◽

Vol 61 (7) ◽

pp. 1100-1104 ◽

Cited By ~ 43

Author(s):

Thomas Axenrot ◽

Tomas Didrikas ◽

Charlotte Danielsson ◽

Sture Hansson

Keyword(s):

Pelagic Fish ◽

Strength Distribution ◽

Fish Distribution ◽

Target Strength ◽

Diel Variation ◽

Fish Behaviour ◽

Additional Information ◽

Diel Patterns ◽

The Baltic ◽

Survey Planning

Abstract Diel variation in pelagic fish distribution influences hydroacoustic abundance estimates. To study and quantify diel patterns in behaviour and spatial distribution in pelagic fish without causing avoidance reactions or attraction to any floating equipment or vessel we used a bottom-mounted, upward-facing transducer. Light intensities were measured as skylight and underwater light (at 5-m depth). The study was performed in a coastal area in the Baltic Sea, late July to mid-August in 2001 and 2002. The results provided additional information on fish behaviour and distribution valuable for future survey planning and in the analyses of hydroacoustic data from regular surveys in this area. At night, the data on hydroacoustic backscattering (sA) were less variable, the vertical distribution of fish was more even, with fewer fish in the deepest layer, and the percentage of single-echo detections was higher. The tilt angle of fish seemed to differ day and night, but trawling and target-strength distribution results taken together also implied a partial diel change in the fish assemblage in the midwater layers. The processes of formation and disintegration of schools happened rapidly and coincided with day and night transition periods.

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