Nearly 10 years have passed since the ter­rorist attacks of Sept. 11, 2001, trans­formed the world for­ever and reshaped America’s views on many aspects of life, including national defense. At North­eastern Uni­ver­sity, researchers are con­ducting ground­breaking work in areas such as explo­sives detec­tion, cyber defense, robotics and data secu­rity. We asked Michael Sile­vitch, co-​​director of ALERT (Aware­ness and Local­iza­tion of Explosives-​​Related Threats), a multi-​​university Depart­ment of Home­land Secu­rity Center of Excel­lence, to elab­o­rate on the University’s inno­v­a­tive secu­rity research.

How did 9/​11 change the nation’s per­cep­tion of home­land security?

Clearly, before the event, we as a country felt fairly secure and rel­a­tively impreg­nable in terms of the issues of for­eign ter­rorism. Since 9/​11, it’s been very clear we are engaged in a world­wide struggle, not just over­seas but one that has a direct impact on our national secu­rity. The Depart­ment of Home­land Secu­rity has been formed and devel­oped at a fairly rapid pace. We now have an infra­struc­ture within the country for home­land secu­rity to deal with attacks within our borders.

How far have we come as a nation, and what chal­lenges remain?

My own exper­tise is in explo­sive detec­tion, mit­i­ga­tion and response, which is the theme of our ALERT Center. Within that domain, there are sev­eral grand chal­lenges, including whether we can achieve unequiv­ocal reli­a­bility in screening pas­sen­gers and lug­gage at air­ports for explo­sives and other threats. We’ve made progress in enhancing the per­for­mance of devices and methods to screen people with better reli­a­bility and lower the false alarm rate. On the other hand, ter­ror­ists are designing the threats of tomorrow, such as home­made explo­sives. We need to main­tain the speci­ficity of the screening equip­ment that will allow screeners to keep abreast of the new com­pounds that need to be sifted.

A second grand chal­lenge is iden­ti­fying a threat a foot­ball field away. In places where there is no gateway to the event, can you scan crowds with tech­nology to deter­mine whether some­thing is threat­ening or non-​​threatening? That is one of the main areas of our research, in terms of devices like radar equip­ment that will beam elec­tro­mag­netic radi­a­tion at a poten­tial sub­ject to see if a signal cor­re­lates to metal being car­ried — like a sui­cide bomber’s vest or an anom­alous shape. Video ana­lytics in screening crowds for anom­alous behavior is another area of interest.

We’re also focusing on pre– and post-​​blast mit­i­ga­tion — detecting the pres­ence of an explo­sive and somehow min­i­mizing the impact of the blast before­hand or pro­tecting our­selves more effec­tively against shrapnel and col­lapsed buildings.

What are the latest projects you and your col­leagues are working on at the ALERT Center?

In the area of highly reli­able screening, we’re working on tech­nolo­gies that will do a better job of imaging inside of carry-​​on and checked bags, using advanced recon­struc­tion algo­rithms, com­puter tomog­raphy and x-​​ray tech­nology. We’re looking at ways of min­i­mizing the burden on the equip­ment oper­a­tors, because they screen many pieces of lug­gage con­tin­u­ally and we want to aid them with more flags to look into.
Another area of interest is the screening of pas­sen­gers at an air­port portal. We’re looking to make that a more reli­able process to intro­duce mul­tiple sen­sors that act together.

We’re also looking at some fun­da­mental research in the nature of explo­sives them­selves. What makes a mate­rial become explo­sive? How does it form at the nanoscale? There are a lot of inter­esting physics and chem­istry processes that are going on in that small scale, in terms of such things as hotspots forming within the mate­rial. We’re also looking at designing blast resis­tant mate­rials that mimic effec­tive struc­tures that occur in nature.