Handheld sonar significantly reduces the mean duration to locate a missing diver as well as increasing users' confidence in their ability to find a missing diver when compared with standard search techniques.Ĭopyright © 2013 Wilderness Medical Society. 001), whereas the standard group decreased in confidence (not statistically significant, P =. Using paired samples t tests, the sonar group's self-assessed confidence increased significantly after using the sonar (P <. Pressure-recording devices in the drill stem test tool measure and record pressure in the well while it is both flowing and not flowing (shut in). The total length of the sounder cable is from ground surface (usually top of the well casing) down to the pump level. Figure 1 Electric Well Sounder Custom-make the electric sounder to your specific situation. The test allows fluids in the formation being evaluated to flow into the drill stem and to the surface. well depth and the desired sophistication, material costs will range from 40 to 80 compared to400 plus for purchasing a well sounder. This is the most commonly used pumping test method for obtaining estimates of aquifer properties. Constant-rate tests maintain pumping at the control well at a constant rate. Using the nonparametric related samples Wilcoxon signed rank test, actual times between the sonar group and the standard group were significant (P <. A drill stem test (DST) is a method of formation evaluation. Common types of pumping tests that you may perform include the following. When the wires touch the water, the electrical circuit closes triggering a milli-Ohm meter and a buzzer. To measure depth to groundwater, a two-wire cable with open ends is lowered into the well. In the sonar-assisted search group, the missing diver was found by all 10 participants (100%), taking an average of 2 minutes and 47 seconds (SD 1 minute, 20 seconds). water well sounder is a standard tool of the trade for groundwater hydrogeologists, water well drillers and pump installers. Using a standard search pattern, the missing diver was found by only 1 diver (10%), taking 18 minutes and 45 seconds. In well-test analysis, a diagnostic plot is a scatter plot of both drawdown and its logarithmic derivative versus time. In a surfing embodiment, the sonar device is integrated into the users surfboard. For each search method, successful completion of the search was defined as locating the missing diver within 40 minutes. 0004 The present invention is a personal sonar system that can be used in most water sport applications and comprises a sonar transducer, a processor and an output device. The modified search used a sonar beacon to augment the search. The standard search utilized a conventional search pattern starting at the point where the missing diver (simulated) was last seen. Participants conducted both a standard and modified search to locate a simulated missing diver. This institutional review board approved, prospective, crossover study used a voluntary convenience sample of 10 scuba divers. The purpose of this study was to investigate whether a handheld sonar device significantly reduces the mean time needed to locate a missing diver.
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