New single echo detection methods for shallow water fishery acoustics

Sonar provides vessels with a sensory system to detect and identify still and moving obstacles. In shallow water both active and passive sonar meet their limits. Acoustical methods exist, aiming at supporting sonar systems by means of digital signal processing, or, coming from the field of biomimetics, imitating echolocation principles of marine animals. This paper introduces a sensor system combining these approaches by the use of a vector sensor array applying Near-field Acoustical Holography (NAH) imitating the Lateral Line organ (LL) of fish; a passive method to supplement active and passive sonar. LL is able to localize obstacles due to their dipole-like water displacement by comparing low-frequency water accelerations distributed along the whole body. In contrast to pressure, accelerations are highly evanescent and do not propagate into the far-field. Thus LL does not suffer under reverberation or scattering. The performance of the proposed NAH-based LL-sensor is tested by a computer simulation of a source in absence and in presence of a disturbing source. The LL-sensor has proven to be more robust than pressure detection methods like beamforming and conventional NAH.

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Echo detection enhancement using multiple guide sources in shallow water

The Journal of the Acoustical Society of America ◽

10.1121/1.4788349 ◽

2006 ◽

Vol 120 (5) ◽

pp. 3260-3260

Author(s):

David C. Calvo ◽

Charles F. Gaumond ◽

David M. Fromm ◽

Richard Menis

Keyword(s):

Shallow Water ◽

Echo Detection ◽

Detection Enhancement

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Dual Gradient Drilling Will Control Shallow Hazards in Deepwater Environments

Volume 7: Offshore Geotechnics; Petroleum Technology ◽

10.1115/omae2009-79790 ◽

2009 ◽

Cited By ~ 1

Author(s):

Brandee A. Elieff ◽

Jerome J. Schubert

Keyword(s):

Shallow Water ◽

Closed System ◽

Drilling Fluid ◽

Detection Methods ◽

Methane Hydrates ◽

Shallow Gas ◽

Well Control ◽

Water Flows ◽

Shallow Water Flows ◽

Dual Gradient

Currently the “Pump and Dump” method employed by Exploration and Production (E&P) companies in deepwater is simply not enough to control increasingly dangerous and unpredictable shallow hazards. “Pump and Dump” requires a heavy dependence on accurate seismic data to avoid shallow gas zones; the kick detection methods are slow and unreliable, which results in a need for visual kick detection; and it does not offer dynamic well control methods of managing shallow hazards such as methane hydrates, shallow gas and shallow water flows. These negative aspects of “Pump and Dump” are in addition to the environmental impact, high drilling fluid (mud) costs and limited mud options. Dual gradient technology offers a closed system, which improves drilling most simply because the mud within the system is recycled. The amount of required mud is reduced, the variety of acceptable mud types is increased and chemical additives to the mud become an option. This closed system also offers more accurate and faster kick detection methods in addition to those that are already used in the “Pump and Dump” method. It has the potential to prevent the formation of hydrates by adding hydrate inhibitors to the drilling mud. And more significantly, this system successfully controls dissociating methane hydrates, over pressured shallow gas zones and shallow water flows. Dual gradient technology improves deepwater drilling operations by removing fluid constraints and offering proactive well control over dissociating hydrates, shallow water flows and over pressured shallow gas zones. There are several clear advantages for dual gradient technology: economic, technical and significantly improved safety, which is achieved through superior well control.

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Coherent creation and destruction of orbital wavepackets in Si:P with electrical and optical read-out

Nature Communications ◽

10.1038/ncomms7549 ◽

2015 ◽

Vol 6 (1) ◽

Cited By ~ 24

Author(s):

K.L. Litvinenko ◽

E.T. Bowyer ◽

P.T. Greenland ◽

N. Stavrias ◽

Juerong Li ◽

...

Keyword(s):

Orbital Motion ◽

Exchange Interactions ◽

Optical Excitation ◽

Nitrogen Vacancy ◽

Detection Methods ◽

Level System ◽

Magnetic Exchange ◽

Inas Quantum Dots ◽

All Optical ◽

Echo Detection

Abstract The ability to control dynamics of quantum states by optical interference, and subsequent electrical read-out, is crucial for solid state quantum technologies. Ramsey interference has been successfully observed for spins in silicon and nitrogen vacancy centres in diamond, and for orbital motion in InAs quantum dots. Here we demonstrate terahertz optical excitation, manipulation and destruction via Ramsey interference of orbital wavepackets in Si:P with electrical read-out. We show milliradian control over the wavefunction phase for the two-level system formed by the 1s and 2p states. The results have been verified by all-optical echo detection methods, sensitive only to coherent excitations in the sample. The experiments open a route to exploitation of donors in silicon for atom trap physics, with concomitant potential for quantum computing schemes, which rely on orbital superpositions to, for example, gate the magnetic exchange interactions between impurities.

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Recent Developments of Exploration and Detection of Shallow-Water Hydrothermal Systems

Sustainability ◽

10.3390/su12219109 ◽

2020 ◽

Vol 12 (21) ◽

pp. 9109

Author(s):

Zhujun Zhang ◽

Wei Fan ◽

Weicheng Bao ◽

Chen-Tung A Chen ◽

Shuo Liu ◽

...

Keyword(s):

Shallow Water ◽

Hydrothermal Vents ◽

Life Forms ◽

Hydrothermal Systems ◽

Detection Methods ◽

Data Types ◽

Close Relationship ◽

Recent Developments ◽

Favorable Conditions ◽

Improved Accuracy

A hydrothermal vent system is one of the most unique marine environments on Earth. The cycling hydrothermal fluid hosts favorable conditions for unique life forms and novel mineralization mechanisms, which have attracted the interests of researchers in fields of biological, chemical and geological studies. Shallow-water hydrothermal vents located in coastal areas are suitable for hydrothermal studies due to their close relationship with human activities. This paper presents a summary of the developments in exploration and detection methods for shallow-water hydrothermal systems. Mapping and measuring approaches of vents, together with newly developed equipment, including sensors, measuring systems and water samplers, are included. These techniques provide scientists with improved accuracy, efficiency or even extended data types while studying shallow-water hydrothermal systems. Further development of these techniques may provide new potential for hydrothermal studies and relevant studies in fields of geology, origins of life and astrobiology.

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DNA nick end labeling: a reliable marker for apoptosis?

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141184 ◽

1995 ◽

Vol 53 ◽

pp. 962-963

Author(s):

Anne F. Bushnell ◽

Sarah Webster ◽

Lynn S. Perlmutter

Keyword(s):

Cell Death ◽

Cultured Cells ◽

Apoptotic Cell ◽

Morphological Characteristics ◽

Detection Methods ◽

Tissue Preparation ◽

Preparation Methods ◽

Dna Laddering ◽

Disease States ◽

Reliable Marker

Apoptosis, or programmed cell death, is an important mechanism in development and in diverse disease states. The morphological characteristics of apoptosis were first identified using the electron microscope. Since then, DNA laddering on agarose gels was found to correlate well with apoptotic cell death in cultured cells of dissimilar origins. Recently numerous DNA nick end labeling methods have been developed in an attempt to visualize, at the light microscopic level, the apoptotic cells responsible for DNA laddering.The present studies were designed to compare various tissue processing techniques and staining methods to assess the occurrence of apoptosis in post mortem tissue from Alzheimer's diseased (AD) and control human brains by DNA nick end labeling methods. Three tissue preparation methods and two commercial DNA nick end labeling kits were evaluated: the Apoptag kit from Oncor and the Biotin-21 dUTP 3' end labeling kit from Clontech. The detection methods of the two kits differed in that the Oncor kit used digoxigenin dUTP and anti-digoxigenin-peroxidase and the Clontech used biotinylated dUTP and avidinperoxidase. Both used 3-3' diaminobenzidine (DAB) for final color development.

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