A study found wireless signals are able to pass through bags and suitcases to judge the sizes

A study found wireless signals are able to pass through bags and suitcases to judge the sizes of dangerous metal objects and identify them. “These items could include weapons, chemicals, laptops and batteries for bombs,” the research team said on Tuesday.
Research suggested that Wi-Fi can now be used to estimate the volume of liquids such as water, acid, alcohol and other chemicals for explosive material. The study led by researchers at the Wireless Information Network Laboratory(WINLAB)in the School of Engineering showed a wireless device with two to three antennas(天线)that could be fitted in existing Wi-Fi networks.
The detection system analyzes what happens when wireless signals go through and bounce off objects or materials. The approach, which the paper states, works by separating the wireless interference(干扰)caused by two factors of objects - the material and shape. “Most dangerous objects such as weapons are usually metal or liquid, which have significant interference,” researchers said.
When it was tested on a backpack, the accuracy rate topped 95 percent. “But the accuracy dropped to about 90 percent when objects inside bags are wrapped. And the tech could save lives if used in museums, stadiums, theme parks or schools,” the team said, noting its design can inspect bags or luggage without being an exposure to privacy.
It uses channel state information(CS)that is readily available in low-cost Wi-Fi devices. “This could have a great impact on protecting the public from dangerous objects,” said Yingying Chen, a co-author of the study, “There’s a growing need for that now. In large public areas, it’s hard to set up expensive screening equipment like what’s in airports. Manpower is always needed to check bags and we want to develop a method to try to reduce manpower. “
The peer-reviewed study, which recently won a best paper award at the 2018 IEEE Conference on Communications and Network Security, is now published online. “Future work will continue to focus on ameliorating the accuracy of identifying objects and imaging shapes and volumes,” researchers said.
32. What does paragraph 3 talk about?
A. The function of the technique.
B. The way the device works.
C. The principle the study is based on.
D. The benefit of the study findings.
33. What’s the advantage of the device?
A. It saves people in danger of natural disasters.
B. It passes through bags without damaging them.
C. It uses antennas to pick up networks’ signals.
D. It protects personal information from being exposed.
34. Why did the researchers study the device according to Yingying Chen?
A. To save money and labour.
B. To make full use of Wi-Fi.
C. To protect passengers’ privacy.
D. To research dangerous objects.
35. Which of the following can replace the underlined word “ameliorating” in the last paragraph?
A. Confirming. B. Improving.
C. Discovering. D. Examining.

答案