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Electromagnetic "wireless" techniques are ineffective for communicating through a solid steel barrier due to the shielding effect of the metal. Although holes can be made in the barrier to allow wires to pass through, they are often undesirable because they can reduce the integrity of the barrier. In contrast, ultrasound propagates readily through steel and can be used to convey information...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.