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Newsletter:  May 2003/ Issue 4
The Acoustic Inspection Device:  A Leap in Container Safety 

The US Customs Service is currently testing a customized version of the Acoustic Inspection Device (AID), known as the Customs Handheld Acoustic Inspection System (CHAIS). It is anticipated that this system will greatly improve the ability of Customs inspectors to conduct fast, thorough and accurate screenings of packages and containers entering the United State’s borders, vastly improving security.

Container safety has been of special concern since September 11 resulting in the Customs Service’s Container Security Initiative, to improve port and maritime security without interrupting the flow of trade—a considerable challenge—and the Service’s arrangement with Mehl, Griffith and Bartek Ltd., located in Arlington, Virginia, to have AID customized and mass produced for use by its inspectors.

AID, created by scientists at Pacific Northwest National Laboratory (PNNL), consists of a hand-held, battery-operated sensor unit, approximately the size of a cordless drill, and a handheld PC the size of a palm pilot that operates on a Windows CE platform. The user simply contacts the sensor to the container in question and it transmits ultrasonic pulses that reflect back, resulting in a precise sonic signature that is then compared with a database of such signatures for identification of the contents. In effect, it works similarly to an X-ray, yet poses no hazard to the user.

As explained by Aaron Diaz, AID project manager at PNNL, “The database has a variety of different liquids and solids and the acoustic measurement data associated with each as a function of temperature and frequency.”

The reading for water, for example, would be 1.48 km/s, signifying the acoustic velocity of the fluid. If there is no signature, then there is either something blocking the sound waves, or the container is empty.

The potential of CHAIS for increasing national and international commercial security is enormous. 90 percent of global cargo is transported by containers via ship, rail or by trucks. The United States receives 16 million such containers through the nation’s 301 ports of entry each year, of which Customs agents inspect only about two percent.

During a hearing of the US House Coast Guard and Maritime Transportation Subcommittee last year, Richard Larrabee, Director of Port Commerce for the Port Authority of New York and New Jersey, stated, “In the Port of New York and New Jersey, Customs estimates that increasing the exam rate (of incoming cargo) to five percent would generate a backlog of 4,500 containers monthly, require an additional 400 inspectors and cost the industry an extra $1.2 million a month.”

CHAIS, lightweight, simple to use, and noninvasive, makes it possible to screen a significantly higher number of drums, tanks or containers passing through checkpoints. It also increases the accuracy of screenings and reduces the health and safety risks associated with traditional inspection methods.

According to Diaz, AID was originally created under contract with the Department of Defense, which sought a hand-held device for weapons inspections in Iraq after the Gulf War. Different versions of the device, with their own specialized data libraries, exist and are used, for instance, by the Czech Republic, Lithuania and Kazakhstan for anti-smuggling purposes, and by the Internal Revenue Service to verify fuel compliance (fuels used for farming and recreation are taxed differently). It has also been used by border agents in Russia, Georgia, Poland, Cyprus, Malta and Uzbekistan, and is a candidate for use for verification purposes under the Chemical Weapons Convention.

“AID has evolved over the last ten to twelve years from a very primitive device to one that is hand-held and ‘intelligent’,” stated Diaz.

It can detect hidden objects inside containers, locating contraband materials. It can discriminate between a variety of different solids and liquids, enabling it to differentiate, for example, between milk, diesel fuel and chemical weapons agents. And, it (Continued on next page) can measure the fill-level of a liquid in a container.

However its current form does have its limitations, and continues to be refined. PNNL scientists are endeavoring to develop increased reliability and consistency of readings. Developers are also working to enable the device to screen containers that are less than the current four- to six-inch diameter limitation, and to reduce the size of the device itself.

“These days smaller is always better,” remarked Diaz.