Chapter 799 Email that affects the entire history of mathematics
In the previous letter sent to Chang Haonan, Li Yabo had already expressed his hope to use structural mechanics as a research field.
However, "structural mechanics" is still a huge scope after all, and most people can only choose a more specific direction of specialization in their lifetime.
Not to mention a mere graduation project.
Of course, under normal circumstances, undergraduate projects are just handed over to a certain senior brother or sister, and they can get acquainted with the research group and project at the same time, and then it is almost over.
However, as Chang Haonan's first disciple, Li Yabo's treatment was naturally extraordinary——
Chang Haonan was going to take him under his belt personally.
The kind that starts with formulating a training plan.
But at present, Chang Haonan only has one turbofan 10 project left at hand.
Li Yabo is still just an undergraduate after all.
No matter from the perspective of ability or confidentiality, it is not suitable for him to be directly exposed to a project of this level -
Chang Haonan's direct participation in the August 3rd Project was a special situation after all, and it could not be used as a routine.
So, let the other party choose.
Anyway, with Chang Haonan's current position in the Science and Technology Commission system, he can get projects immediately as long as the direction is not too outrageous.
And Li Yabo did not disappoint.
Such a specific and targeted answer has obviously been considered long ago.
Thin-walled boxes made of composite materials can be considered a subject with a very wide range of applications.
And very prophetic.
The "box" here is not limited to horizontal and vertical hexahedrons, but also includes cylinders, ellipsoids or other irregular shapes.
Basically, it is the main research direction in the aerospace field in the next twenty to thirty years.
For example, the body of large passenger aircraft and the casings of rockets and missiles will gradually increase the amount of composite materials used to reduce the structural weight.
For example, when Eurocopter designed the NH90, it had already considered using a large number of composite materials in the fuselage.
It’s just that the operating environment of helicopters is indeed quite harsh. Giving up ease of maintenance and damage resistance for the sake of a small amount of weight is a waste of watermelon, so Chang Haonan stopped it.
However, at the end of the 1990s, the application of composite materials was still a cutting-edge field. It is really surprising that a senior undergraduate student could choose it so accurately.
“Tell me why you want to go in this direction?”
Chang Haonan asked.
“Didn’t I work on a small UAV structural design project with Mr. Li Guang... At the beginning, because the engine provided by Party A was not powerful enough, Mr. Li considered completely replacing metal with carbon fiber. Making the body of the drone. ”
“But in the end, because we had never done any research in this area before, Party A was worried that the design would be too risky, and of course there were cost issues. In the end, we ended up using magnesium aluminum. Alloy.”
Chang Haonan was speechless for a moment.
It is indeed risky to consider a 100% composite body.
At present, Huaxia aircraft generally uses less composite materials, and its main applications are secondary skins and other locations that do not bear high loads.
"So...how was the problem of the overweight body solved in the end?"
This question is purely out of curiosity.
The intersection between Chang Haonan and Professor Li Guang was limited to when they were first reborn. The other party served as a judge in Teacher Liu Hongbo's class and was shocked by his design plan.
So the former is not sure what the drone project is about.
"It's not solved."
Li Yabo replied:
"Party A later replaced the piston engine in the original plan with a more powerful light turboprop, so the overweight is also overweight. , that project does not have high requirements for us, basically it only needs to be able to fly..."
"Okay"
Chang Haonan never expected that it would be such a powerful brick. Fei's ending:
"Now that you are sure, let's go in this direction."
After saying that, he lowered his head and thought for a moment:
"However, scientific research must be done step by step. Research on composite material structures is of great significance to our country. ...It’s a brand new topic to the whole world, so we can’t go into large sizes right away..."
"I have some relevant information and literature. I will give you a look today to familiarize yourself with the material. The basic research methods of mechanics and structural mechanics will be officially started after I apply for the project."
"Okay"
After talking about the project, Chang Haonan asked Li Yabo to go to Liu Chenchen to get a stamp to prove that he had indeed entered the research group and completed the topic selection process.
Graduation project is considered a "course" that takes up more than ten credits in the training program.
If the topic opening link is missing, although Chang Haonan can handle it, it is still more troublesome.
"Huh..." Chang Haonan, who saw Li Yabo's back disappearing from the door and almost revealed that he had forgotten about her, finally breathed a sigh of relief, then returned his attention to the computer screen and began to think about how to give her a message. Perelman wrote back.
…
A few days later.
Moscow, Steklov Institute of Mathematics.
Gregory Perelman, who had been working for more than ten hours straight and was about to go home for a break, opened his mailbox as usual and prepared to check if there were any new emails that he needed to deal with.
This is his personal habit.
Plan your next day's work before you leave work the day before, rather than waiting until after you arrive at work that day.
In the past ten years, it has always been like this, unchangeable.
“Invitation to Princeton’s Annual Mathematics Meeting...”
“Millennium Mathematics Prize...”
“Invitation to the Review of the Journal of Mathematics... Heh... look They were affected by the actions of the Annual Journal of Mathematics. They are really idiots. If they continue like this, their influence will never be able to match that of the Annual Journal of Mathematics..."
"..."
Perelman quickly sent emails that he considered unimportant to the recycling bin.
It even included a notice awarding him the Millennium Mathematics Prize and informing him to go and receive the award.
He has no intention of leaving Russia in the near future.
At least I won’t leave because of these “trivial” things.
What Perelman loves is the beauty and mystery of mathematics itself. After successfully proving the soul conjecture a few years ago, he discovered that if he won an award for solving a certain mathematical problem, it would dilute his ability to solve a certain mathematical problem. The joy derived from the problem itself.
From that time on, he refused to accept any personal awards, and even gradually tended to publish his results directly to the public rather than in the form of written papers.
“Wait a minute...”
Just when Perelman thought tomorrow would be another boring day, he suddenly caught a glimpse of an email he had been waiting for.
To be precise, it is a reply letter.
"Finally here..."
He quickly opened it.
About a month ago, he was shocked when he saw this paper published in the Annals of Mathematics.
There is actually another person in the world who is solving the application problem of Ricci flow in three-dimensional conditions with a similar idea to him.
Moreover, it was half a step ahead of him.
So, after getting some inspiration from it, Perelman wrote his thoughts in an email and sent it to the author of the paper.
For more than a week, he did not receive a reply.
Until today.
[Dear Professor Perelman, thank you for your letter. The content of the email has greatly inspired my research...]
Perelman skipped the previous polite words at a glance. .
Fortunately, Chang Haonan's reply style is similar to his, and the second paragraph goes directly to the point:
[I have verified your conclusion and there is no problem, but it seems that the derivation process of the theorem can be more concise. And directly...]
[The role of the non-local collapse theorem is that it can give a local injective radius estimate, and the Ricci flow after surgery can still satisfy this property. In this case, then in Hamilton Based on the injective radius estimation theorem, it can be deduced that for (Mk, gk(t), pk) that satisfies certain conditions, there must be a convergent subsequence...]
[...]
The expression on Perelman's face changed from relaxed to solemn, and then to excitement...
He quickly pulled out a ballpoint pen and a piece of paper from the desk next to him, lowered his head and began to calculate quickly.
"That's right... This verification process should be more straightforward..."
About half an hour later, Perelman looked at the calculation process that only used one positive and negative space. He said to himself excitedly.
Although the content of the theorem proved by Chang Haonan is exactly the same as what he sent before, the process is much simpler.
"In this case, I don't seem to have to worry about those guys not being able to understand my proof process..."
Perelman muttered as he took off his coat and scarf and returned to his desk.
Obviously, the plan to get off work must have been ruined.
"Perhaps, I should go to China in person?"
Looking at the signature of CHANGHaonan at the bottom of the email on the computer screen, he had already given up on his previous thought of "not planning to go abroad in the near future" Forgot everything.
(End of this chapter)