Detection underwater

The Office of Naval Research (ONR) conducted the Chemical Sensing in the Marine Environment (CSME) Program to provide a new tool for detecting underwater UXO. Over the last few years, a number of TNT sensors have been developed and evaluated. 

Quartz and piezoelectric ceramic crystals have more temperature independent constants than PVDF, so they are used for force and acceleration transducers. However, PVDF films can be used for large area flexible transducers. Their sensitivity to stress or strain allows the construction of pressure sensors (using the J33 coefficient), and accelerometers by mounting a seismic mass on the film. PVDF electrets are particularly suited for large area hydrophones (Fig. 12.21) that detect underwater signals. Their... 

Towed Array Cable with a number of underwater microphones used to detect underwater objects across a range of aquatic environments. 

Titanium forms a series of oxoanions called titanates, which are prepared by heating Ti02 with a stoichiometric amount of the oxide or carbonate of a second metal. One of these compounds, barium titanate, BaTi03, is piezoelectric, which means that it becomes electrically charged when it is mechanically distorted. The ability to convert mechanical vibration into an electrical signal makes barium titanate useful for underwater sound detection. 

Short RT, Toler SK, Kibelka GPG, Roa DTR, Bell RJ, Byrne RH (2006) Detection and quantification of chemical plumes using a portable underwater membrane introduction mass spectrometer. Trends Anal Chem 25 637-646... 

Figure ll ICx Technologies SeaDog underwater explosives detection sensor mounted on an autonomous underwater vehicle. Figure courtesy of ICxTechnologies. 

M. Dock, J.E. Sikes, M.E. Fisher, Underwater Explosives Detection Using a Chemical Sensing Method, Sixth International Symposium on Technology and the Mine Problem (MINWAILA),... 

Nylon 11 (Equation 6.56) is also a piezoelectric material that can be aligned when placed in a strong electromagnetic field giving films used in infrared-sensitive cameras, underwater detection devices, and in electronic devices since it can be overlaid with printed circuits. 

Turbulence is not the asset in water that it is in air. In air, we saw that some turbulence is required to bring the molecules out of the chemical boundary layer. That may also be needed in water to move molecules away from the bottom surface. Turbulence away from the surface tends to break up the plumes of molecules that are diagrammed in Figure 4.4. Those plumes are the key to successful detection of an underwater object that is releasing the molecules of interest. One result of the ONR experiment at San Clemente Island, off San Diego, California, was a better understanding of the formation, persistence, and dissipation of these plumes. When a well-formed plume is available, it often becomes possible to follow it to its source see Chapters 5 and 6. 

The underwater sensor platform is derived from the Fido explosives vapor sensor, originally developed under the Defense Advanced Research Projects Agency (DARPA) Dog s Nose Program. The vapor sensor, whose operation is discussed in Chapters 7 and 9 and in other publications [7-9], was developed for the task of landmine detection. The underwater adaptation of the sensor is very similar to the vapor sensor. In the underwater implementation of the sensor, thin films of polymers are deposited onto glass or sapphire substrates. The emission intensity of these films is monitored as water (rather than air) flows past the substrate. If the concentration of TNT in the water beings to rise, the polymer will exhibit a measurable reduction in fluorescence intensity. The reduction in emission intensity is proportional to the concentration of target analyte in the water. Because the sensor is small, lightweight, and consumes little power, it proved to be ideal for deployment on autonomous platforms. 

To our knowledge, this is the first demonstration of a sensor capable of realtime detection of a TNT plume in the marine environment at standoff distances (up to 100 m from the source) while deployed on an autonomous underwater vehicle. The sensor has shown virtually no sensitivity to chemical interferent during testing in the marine environment. While the sensitivity of the detector is excellent, its sensitivity is not adequate at its present state of development to... 

Dock, M., M. Fisher, and C. Cumming. Novel detection apparatus for locating underwater unexploded ordnance, in Proceedings of the 5th International Symposium on Technology and the Mine Problem, Mine Warfare Association, Monterrey, California, April 2002. 

Dock, M., J. Sikes, M. Fisher, and M. Prather. Chemical detection of underwater explosives. 2004 Mine Countermeasures Demining Conference/MINWARA, Canberra, Australia, February 2004. 

Chapter 6, Detection of Trace Explosive Signatures in the Marine Environment. Since the main subject is underwater experience with the SeaDog sensor,... 

In Table 6, reproduced from p 494 of the paper, the pressures, P, of shocks required to produce burning just detectable in underwater test and modified gap test are compared... 

An acronym is a word that is formed from the first letters or parts of a series of words. For example, AIDS (acquired immune deficiency syndrome), radar (radio detecting and ranging), and scuba (self-contained underwater breathing apparatus) are common acronyms. 

The Buccaneer, with its capacity to carry nuclear weapons, was central to the Admiralty s vision of the aircraft carrier as the modem equivalent of the capital ship. In a remarkable paper, dated 2 March 1954, the Admiralty set out its views on expected trends in naval weapons down to the end of 1965. The news of the American hydrogen-bomb tests came too late to influence the paper, which, however, assumed that atomic weapons would be plentiful that the importance of air attack would increase but that long-range detection of submarines and torpedo countermeasures would reduce the underwater threat to surface ships. It was predicted that by the 1960s carrier-borne aircraft would carry nuclear weapons and would contribute to the strategic air offensive aircraft and 200-mile-range anti-ship missiles would have begun to... 

ASDIC Antisubmarine Detection Investigation Committee (Code name for ultrasonic underwater detector)... 

Based upon the foregoing experiences, some researchers observed that the same reluctance to interact with matter is responsible for the neutrino s long range and ability to resist detection. Tlios, it was reasoned that an apparatus for detecting neutrinos should be massive and shielded from the interference of other particles and radiation. As a solution to these problems, some researchers proposed a deep underwater muon and neutrino detector (acronym DUMAND). 

Comparison of Pressure, P, at Which Burning ic juc+ Detectable in the Underwater and Modified Gap Tests... 

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