Li Quan
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Jiangsu Modern Express
February 19, 2014 Wednesday
In martial arts fiction, there’s a martial art called “transmitting sound into secret”. The speaker can condense his/her voice into a beam and send it directly just to a specific person, and no one else at present can hear it. This fictitious martial art in the novel is now coming true! Li Quan, a senior graduate student from the School of Physics at Nanjing University, with his advisor, has worked out a new technology, that when the speaker is speaking, only the listener in front of the speaker can hear the voice. Sound in other directions will “disappear”. This technology has great applications in underwater acoustics, medical ultrasound, etc. al. And this work has been published in world prestigious journal Nature Communications. What surprising is that Li Quan had once failed his course during his undergraduate study. He started to show his potential and get successful after he changed his major. His advisor cherished his talents and recommended him to continue his graduate study.
By Jiangsu Modern Express Reporter: Feng Jin, Correspondent: Yinguo Hou and Peiying Zhu
Have you ever worried about being eavesdropped by others when chatting with friends? From now on, even if you are talking in a crowded public, no one else can hear what you are chatting about. Recently, Li Quan, a senior graduate student from the School of Physics at Nanjing University, with his advisor, has published their unimaginable research result in a world leading prestigious Journal: Nature Communications.
In Li Quan’s own interpretation: when you are speaking, only people standing in front of you can hear your voice. Any one in other directions of the speaker, such as left, right, back, will hear nothing. In other words, your voice can be sent like instructions which can only be received by the targeted person. And you don’t need to worry about your voice being overheard by others.
“How to control low-frequency sound to travel in specific directions is one of the most difficult and critical problems in the world. We proposed a brand-new way that by decorating artificial acoustics micro-structures on the surface of a steel plate, we were able to covert the hard boundary of a steel plate into a soft boundary, which can even be ‘softer’ than air.” said by Li Quan. Interviewed by reporters of Jiangsu Modern Express yesterday, Li Quan, a 26-year-old boy, has already shown his scientific temperament.
Li Quan said: “The application value of this technology is even more obvious in the concert. In the future, by putting this kind of electronic devices on the stage, sound can only be heard by the targeted audience in front of the state. In addition to preventing sound loss, the technology can also prevent disturbing other people in other directions.”
“On aircraft and high-speed railways, where space between people to people is very limited, you can use this electronic device to prevent your voice from disturbing others.” Said by Li Quan.
More importantly, this technology can be used to provide nondestructive testing for railways and constructions. Dr. Xiaozhou Liu, professor in School of Physics at Nanjing University, Li Quan’s advisor, and the corresponding author of the paper, provided his opinion that the current ultrasonic nondestructive tesing method could only find cracks in centimeter level. If this technology was used in nondestructive testing, the detection accuracy could be improved to micrometer. This would have great potential in the nondestructive testing of railways, aircrafts, and constructions to avoid accidents.
The prestigious Nature-brand journals are famous for publishing internationally cutting-edge scientific research results. The review process is extremely strict. This 26-year-old graduate student, Li Quan, who made such a great achievement within just two years of his graduate study surprised a lot of his peers. Actually, his scientific career was almost stopped 3 years ago if he were not recommended to continue his graduate study by this advisor, Prof. Xiaozhou Liu.
In 2011 when Li Quan was graduating, Prof. Xiaozhou Liu along with other two professors strongly recommended that Li Quan should be admitted to the Graduate School of Nanjing University. Thus, the Graduate School made an exception to admit Li Quan as a graduate student.
Li Quan is not the kind of top student in the tradition sense of Chinese people, but he is independent and with insightful ideas. He has shown great interest in the subject of Physics since he was a child. However, in 2007, he did not successfully be admitted to the School of Physics and was admitted to the School of Atmospheric Science at Nanjing University majoring meteorology. “I was not interested in the meteorology major, so I rarely attended the lectures. I invested stocks, slept a lot, played video games a lot at that time.” As a result, Li Quan failed in the Politics course.
In the second semester of his freshman year, he attended an acoustic seminar and the topic interested him a lot. He started to consider changing his major.
Li Quan has a great foundation in Physics. In high school, he won the First Prize in the Shanghai Physics Competition. His physics course grade surpassed his classmates in his freshman year. Finally, he successfully transferred into the Department of Acoustics.
“I have successfully transferred into the new department and majored in my interested subject, there’s no reason to be lazy anymore.” Entering his dream field, he tried his best to learn everything in his field. In his sophomore year, he had to complete more than 40 courses in order to make up those acoustic courses offered in the freshman year. Sometimes when he encountered lectures conflict, he studied the courses by himself.
He started to show his potential and began his success. In his junior year, he signed up the “Undergraduate Innovation Training Program” and met Prof. Xiaozhou Liu, who became his advisor in his graduate study. He then started his research on "the application of nonlinear acoustics to nondestructive testing in metal with micro-cracks " (also referred as "NDT"). “The ultimate goal to educate people is to have them give back and serve the whole society. Although nondestructive testing has been widely used in various industries, the current technology is not able to detect micro-cracks in metals, which can bring many potential safety risks to aerospace, automobile manufacturing, etc.”, Li Quan said. Although this proposal was not selected for fund in the end, it is a start in Li Quan’s research career. And at the same time, this project let Prof. Xiaozhou Liu saw Li Quan’s potential in this field. “He is not an extremely hardworking student, but he is very smart. Once you give him a direction, he can make great progress via theoretical analysis and experiment.”, Prof. Xiaozhou Liu said.
In his junior year, the university encouraged students to participate in the National Undergraduate Electronics Design Contest. Li Quan didn’t pass the first-round selection. Later on, Li Quan joined another group. In this “voice-controlled car” project, Li Quan along with other two students, realized guiding the car to move into a specific location by putting a speaker in the car with three receivers in the corners. In the end, this project won the first prize in the competition in Jiangsu Division.
In addition to do his research, this 26-year-old boy also started to pay attention to public affairs of the university and tried to talk to the President and Provost. In 2009, Nanjing University introduced an education reform and Li Quan wrote a letter with nearly 4000 words to the President’s mail box.
At that time, he challenged the way instructors taught the ideological and political courses. “You can imagine the low attendance rate of the ideological political lectures. But if we change the practice and use the live examples of some famous professors to teach student, what kind of education effect can we receive?” Li Quan said.
On campus, Li Quan noticed that some students threw rubbish on school walkways. In the canteen, students usually left their plates on the table without collection. On rainy days, many students would put their wet umbrellas on the seats. In the classroom, student usually wear slippers into the classroom. And some student might answer their phone call during the lecture.
In the letter, he provided his own view, "The reform of the curriculum system and curriculum setting is a relatively easy part in general education. The difficulty is how to cultivate a college student to have a good and positive personality and value." He believed that this could not be acquired through the textbooks and exams. The only way was to let student to understand, experience and comprehend. “What teachers can do is to provide examples of famous professors to the students and set up positive values to them.”, Li Quan said.
In 2010, Li Quan’s junior year, he had to choose whether to continue his graduate study or to seek a job in industry. Based on his GPA ranking, he is not eligible to be directly admitted to the Graduate School. Prof. Xiaozhou Liu, along with other two professors strongly recommended that the Graduate School should make an exception to admit Li Quan.
In 2011, Li Quan was successfully admitted to the Department of Acoustics. In the current job seeking season, he has signed a job contract with an IT company. But he said that he will continue his research in the near future.