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

1987 ◽  
Vol 44 (6) ◽  
pp. 1261-1267 ◽  
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.

Analysis of Echo Counting Data: A Model

1984 ◽  
Vol 41 (3) ◽  
pp. 451-458 ◽  
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.

A Bayesian interpretation of target strength data from the Grand Banks

1997 ◽  
Vol 54 (10) ◽  
pp. 2323-2333 ◽  
Author(s):  
T Hammond
Keyword(s):  
Gadus Morhua ◽  
Research Effort ◽  
Target Strength ◽  
Grand Banks ◽  
Dual Beam ◽  
Northern Cod ◽  
Multiple Detection ◽  
Species Groups ◽  
Fish Detection

Knowledge of the target strength (TS) distribution of the fish being surveyed is necessary for accurate acoustic biomass estimates. Although dual-beam and split-beam transducers can measure TS in situ, these measurements are usually misleading because fish with higher TS are detected more readily, measurements are coming from several fish species, and measurements are made on the total echo from several unresolved targets. A Bayesian method of analysis was developed to extract information from TS data despite these problems. The first problem was addressed using a model of fish detection that was calibrated with data from a survey of northern cod (Gadus morhua) on the Grand Banks. The second problem, species composition, was dealt with by incorporating information about the relative abundance of species groups. Prior information about the concentration profile of the species assemblage was used to take into account the third problem, multiple detection. Results suggested that the difficulties mentioned above are serious sources of bias that should not be ignored. The method also indicated how research effort can be directed to improve acoustic surveys.

To Eliminate Curtain Effect of FIB TEM Samples by a Combination of Sample Dicing and Backside Milling

2014 ◽  
Author(s):  
Jian-Shing Luo ◽  
Hsiu Ting Lee
Keyword(s):  
Sample Preparation ◽  
Focused Ion Beam ◽  
Preparation Method ◽  
Low Cost ◽  
Ion Beam ◽  
Sample Preparation Method ◽  
Site Specific ◽  
Dual Beam ◽  
Transmission Electron

Abstract Several methods are used to invert samples 180 deg in a dual beam focused ion beam (FIB) system for backside milling by a specific in-situ lift out system or stages. However, most of those methods occupied too much time on FIB systems or requires a specific in-situ lift out system. This paper provides a novel transmission electron microscopy (TEM) sample preparation method to eliminate the curtain effect completely by a combination of backside milling and sample dicing with low cost and less FIB time. The procedures of the TEM pre-thinned sample preparation method using a combination of sample dicing and backside milling are described step by step. From the analysis results, the method has applied successfully to eliminate the curtain effect of dual beam FIB TEM samples for both random and site specific addresses.

In-Situ Dual Beam (FIBSEM) Techniques for Probe Pad Deposition and Dielectric Integrity Inspection in 0.2 μm Technology DRAM Single Cells

1999 ◽  
Author(s):  
Gunnar Zimmermann ◽  
Richard Chapman
Keyword(s):  
Electron Beam ◽  
Single Cell ◽  
Single Cells ◽  
Ion Beam ◽  
Gate Oxide ◽  
Ion Milling ◽  
Dual Beam ◽  
Sem Imaging ◽  
Innovative Techniques

Abstract Dual beam FIBSEM systems invite the use of innovative techniques to localize IC fails both electrically and physically. For electrical localization, we present a quick and reliable in-situ FIBSEM technique to deposit probe pads with very low parasitic leakage (Ipara < 4E-11A at 3V). The probe pads were Pt, deposited with ion beam assistance, on top of highly insulating SiOx, deposited with electron beam assistance. The buried plate (n-Band), p-well, wordline and bitline of a failing and a good 0.2 μm technology DRAM single cell were contacted. Both cells shared the same wordline for direct comparison of cell characteristics. Through this technique we electrically isolated the fail to a single cell by detecting leakage between the polysilicon wordline gate and the cell diffusion. For physical localization, we present a completely in-situ FIBSEM technique that combines ion milling, XeF2 staining and SEM imaging. With this technique, the electrically isolated fail was found to be a hole in the gate oxide at the bad cell.

Analyses of Echo-traces of Individual Fish Obtained in situ by Dual-beam Method.

1993 ◽  
Vol 59 (6) ◽  
pp. 943-950 ◽  
Author(s):  
Yoichi Miyanohana ◽  
Koichi Sawada ◽  
Yoshimi Takao ◽  
Masahiko Furusawa
Keyword(s):  
Individual Fish ◽  
Dual Beam ◽  
Beam Method

In situ target strength measurements of the scyphomedusa Chrysaora melanaster

2014 ◽  
Vol 153 ◽  
pp. 18-23 ◽  
Author(s):  
Alex De Robertis ◽  
Kevin Taylor
Keyword(s):  
Target Strength

scholarly journals The study of the acoustic target strength of Chub mackerel in the northwestern Pacific Ocean in situ

Trudy VNIRO ◽  
2021 ◽  
Vol 184 ◽  
pp. 73-86
Author(s):  
M.Yu. Kuznetsov ◽  
◽  
V.I. Polyanichko ◽  
E.V. Syrovatkin ◽  
I.A. Ubarchuk ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Target Strength ◽  
Northwestern Pacific ◽  
Chub Mackerel ◽  
Northwestern Pacific Ocean ◽  
Acoustic Target
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