A Semiautomated Approach to Estimating Fish Size, Abundance, and Behavior from Dual-Frequency Identification Sonar (DIDSON) Data

2008 ◽  
Vol 28 (3) ◽  
pp. 799-807 ◽  
Author(s):  
Kevin M. Boswell ◽  
Matthew P. Wilson ◽  
James H. Cowan
Keyword(s):  
Dual Frequency ◽  
Fish Size ◽  
Frequency Identification ◽  
And Behavior

Gray Seal Behavior in a Fish Weir Observed Using Dual-Frequency Identification Sonar

2014 ◽  
Vol 48 (4) ◽  
pp. 72-78 ◽  
Author(s):  
Owen C. Nichols ◽  
Ernie Eldredge ◽  
Steven X. Cadrin
Keyword(s):  
Halichoerus Grypus ◽  
Fishing Gear ◽  
Dual Frequency ◽  
Pomatomus Saltatrix ◽  
Negative Effects ◽  
Behavioral Observations ◽  
Frequency Identification ◽  
And Behavior ◽  
Fish Weir ◽  
Gray Seals

AbstractMarine mammal depredation can have significant negative effects on the performance of fixed fishing gears. Gray seals (Halichoerus grypus grypus) have been observed feeding on fish weir catches in Nantucket Sound, and remnants of longfin inshore squid (Doryteuthis pealeii) and finfish in the nets are attributable to seal depredation. A dual-frequency identification sonar (DIDSON) deployed in a weir to monitor squid and fish occurrence captured observations of seal presence and behavior. Continuous recordings of 24+ h were subsampled at multiple intervals to optimize the likelihood of seal detection while minimizing processing time. Targets detected and identified to species included squid, bluefish (Pomatomus saltatrix), and gray seals. Seal occurrence in the weir was observed primarily at night. The presence and behavior of seals may negatively affect the efficiency of the weir due to disruption of the passage of schooling squid and finfish into the catch chamber. Behavioral observations collected using DIDSON can aid in the design of fishing gear modifications to reduce seal depredation.

scholarly journals The complexity of narrowband echo envelopes as a function of fish side-aspect angle

2007 ◽  
Vol 64 (5) ◽  
pp. 1066-1074 ◽  
Author(s):  
Debby L. Burwen ◽  
Patrick A. Nealson ◽  
Steven J. Fleischman ◽  
Timothy J. Mulligan ◽  
John K. Horne
Keyword(s):  
High Frequency ◽  
Acoustic Signals ◽  
Pronounced Effect ◽  
Target Strength ◽  
Marine Science ◽  
Dual Frequency ◽  
Fish Size ◽  
Aspect Angle ◽  
Frequency Identification ◽  
Better Than

Abstract Burwen, D. L., Nealson, P. A., Fleischman, S. J., Mulligan, T. J., and Horne, J. K. 2007. The complexity of narrowband echo envelopes as a function of fish side-aspect angle. – ICES Journal of Marine Science, 64: 1066–1074. High-frequency, narrowband acoustic signals may contain more information on fish size and orientation than previously thought. Our observations of dual frequency identification sonar (DIDSON) images of fish orientation paired with split-beam echo envelopes helped clarify why metrics such as echo duration have performed better than target strength measurements when predicting salmon lengths at side aspect. Fish orientation has a pronounced effect on the duration and shape of split-beam echo envelopes from large (80–130 cm) salmon insonified at side aspect. At near-normal aspect angles, echo envelopes are unimodal, symmetrical, and resemble echo envelopes from calibration spheres. With increasing oblique-aspect angle, echo shapes become less symmetrical as the number of peaks increases, and echo duration and amplitude become more variable. Using angle and range coordinates, peaks in an echo envelope can be traced to their origin on a DIDSON image. At oblique-aspect angles, discrete peaks develop that are reflected from regions close to the head and tail. In addition, the distance between peaks increases with increasing aspect angle and is larger than can be explained by swimbladder length.

A Novel Dual-Band Tag Antenna for RFID Application

2013 ◽  
Vol 427-429 ◽  
pp. 1289-1292
Author(s):  
Yan Zhong Yu ◽  
Hua Nan Yang ◽  
Zhong Yi Huang
Keyword(s):  
Radio Frequency Identification ◽  
Rapid Development ◽  
High Gain ◽  
Dual Band ◽  
Dual Frequency ◽  
Rfid Tag ◽  
Microstrip Patch ◽  
Frequency Identification ◽  
Design Requirements ◽  
Simulation Results

With the rapid development of RFID (radio frequency identification) application, the design requirements of RFID tag antenna are also increasing. A design of dual-frequency or multi-frequency tag antenna has become fashionable. In the present paper, we design a dual-band RFID tag antenna, which consists of a bent microstrip patch and rectangular microstrip patch. The designed antenna is analyzed and optimized by HFSS13. Simulation results indicate that the tag antenna has the characteristics of double band, high gain, and good radiation pattern.

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