Chapter 187 The End of Sonar

Not only Hu Xinrui came, but also two other scholars, both of whom looked older than Hu Xinrui.

Hu Xinrui just has sparse hair, but one of the other two has bald hair and the other is completely bald.

The consequence of total baldness is that although he is young in every aspect, he looks older than a middle-aged man.

Chen Yuanguang couldn't help but think, is this the price of becoming stronger? That's too painful.

"Yuan Guang, this is Professor Wei Rongzhao. He is also a direct disciple of Academician Wang Dezhao. Wang Dezhao is the founder of our country's national defense acoustics." Hu Xinrui introduced.

Wei Rongzhao stood up and shook hands with Chen Yuanguang: "Academician Chen, I have long heard of your name." He said nothing more after that.

Hu Xinrui continued, "This is Professor Jiang Zhonghua, a professor at Jinling University.

He is also a professor who is working on the cutting-edge applications of topological materials in the field of acoustics. We consider that the direction you are working in is too cutting-edge and we two alone may not be able to understand it.

So we specially asked Professor Jiang to come and give us some help. "

After Jiang Zhonghua stood up, he also exchanged some general greetings.

Chen Yuanguang was quite interested in Jiang Zhonghua's research direction: "Professor Jiang, what exactly are you doing?"

As an academician, Chen Yuanguang's status and power are enough to allow him to ask questions in a mentor-like position.

“It’s mainly condensed matter physics, such as thermoelectric effect, photonic crystals, topological effects in wave systems, strong correlation effects in optical systems, etc.

Previously, I took on a national key scientific research project, the cutting-edge application research of meta-acoustic materials. This project is highly related to submarine stealth.

Professor Wei was worried that you were using topological materials and that he alone could not follow your ideas, so he called me over. "

Only when enough funds are invested in scientific research and the scientific research team is large enough can we have corresponding talents in every sub-field.

Due to limited resources, China's strategy in scientific research is to cast a wide net. After all, there are people in every field. Not many, but there must be some. Once there is a breakthrough in this field, whether at home or abroad, then more resources will be invested.

This is a very practical strategy at the moment.

Such a strategy can ensure that you are not left too far behind.

After listening to this, Chen Yuanguang said: "Okay, I understand."

This is the bad part. You have to tell the other party all your thoughts during the material research and development process, so as to cover up the rationality of your coming up with these technologies.

In fact, Chen Yuanguang didn't want to talk too much, because the more he talked, the easier it would be to bring up new problems, and then it would be difficult to explain these new problems using the existing theoretical framework.

"We all know that the acoustic coating materials used on submarines are mainly divided into two categories according to their functions: decoupling tiles for sound insulation and anechoic tiles for sound absorption.

The main function of the decoupling tile is to reduce the radiation noise and self-noise of the submarine. The anechoic tile reduces the target intensity characteristics of the submarine and the reflection of active sonar sound waves.

But in recent years, with the deepening of research in the field of materials, some new sound-absorbing coatings actually have both functions.

Professors, since you have learned about my research direction before you came here, I guess you should have some knowledge about acoustic metamaterials and one-dimensional superconducting materials for room-temperature superconducting schemes?"

Jiang Zhonghua knew what the other party was talking about. He was referring to the article published by Chen Yuanguang in the special editions of Nature and Science when room-temperature superconductivity was discovered.

In the past two years, that article has firmly occupied the throne of the most important paper in the entire material science, and a large number of laboratories around the world are exploring along the direction of Chen Yuanguang.

Although no one has truly replicated room-temperature superconducting materials, many interesting results have been produced. In particular, the idea of ​​using magnetic field control technology to open up pathways at the microscopic level has been applied to many cutting-edge material research.

In a sense, the theory of room-temperature superconductivity has guided the research in materials science in the past two years from a higher level.

"I have read it no less than ten times. When I read many papers in the past two years, they all cited some of the theories in your paper," said Jiang Zhonghua.

After listening to this, Chen Yuanguang nodded and said, "That's good, then what I'm going to say next should not be that difficult to understand.

We still have to start with the material used in Xiaomi Ultra, which is a piezoelectric metamaterial.

But it is composed of two parts of materials, namely the piezoelectric material responsible for sound propagation and the piezoelectric material responsible for sound attenuation.

The latter is what we will focus on today.

When elastic waves within a specific frequency range propagate through a structure, an elastic wave band gap is created.

These band gaps can suppress and absorb elastic wave propagation in the relevant frequency range.

The elastic band gap of the acoustic metamaterial we use is mainly caused by two main mechanisms: Bragg scattering mechanism and local resonance mechanism.

Therefore, according to the different principles of band gap generation, acoustic metamaterials can be divided into Bragg scattering phononic crystals and local resonance acoustic metamaterials.

We mainly use this principle to construct the acoustic metamaterials we need, and use its band gap characteristics to achieve noise reduction.

Its most prominent feature is that the hard boundary of the sound field can meet the underwater pressure requirements. The sound waves in the underwater device flow from the seawater environment to the underwater device. The hard boundary makes the sound pressure zero. "

Jiang Zhonghua immediately grasped the key point after listening to it: "Is it similar to a permanent magnet structure?
The unique elastic wave bandgap characteristics of the permanent magnet structure prevent elastic waves from propagating within the bandgap frequency range it covers, so permanent magnet structures are used to design underwater ships. "

“Yes, you can understand this structure as an application at the micro level.

Because the viscosity of elastic materials can dissipate the mechanical energy of vibration, it absorbs sound waves and passively reduces noise.

Therefore, this time we used the above principle to derive a new composite material that has both viscoelastic and piezoelectric properties.

The piezoelectric material used in Xiaomi cars has gone a step further. This new piezoelectric material can be used underwater.

When we use this material for submarine coatings, we apply a controlled periodic voltage to the piezoelectric material layer to generate the corresponding stress to eliminate reflection, thereby emitting a sound wave with a phase opposite to the vibration.

It should be able to fundamentally solve the problem of insufficient submarine concealment in our country.

It is best to use periodically distributed piezoelectric patches, bond these piezoelectric patches to the surface of the main structure of the submarine, and then use the shunt circuit to work with the patches in self-inductance mode to build multiple band gaps, so that the band gap band can cover as wide a range as possible, thereby achieving a good noise reduction effect. "

Chen Yuanguang stood up and projected the patch structure he designed onto the screen in the conference room.

“Because I don’t have the detailed structural diagram of our country’s submarine, I just used something with a similar shape.

Let me talk about the algorithm I used to use this piezoelectric material patch, how I calculated it, how to design the current, and how to stick the patch more reasonably to maximize the noise reduction effect.

You can directly use my ideas, compare them with existing submarine models, and then design them.

This method can improve our combat effectiveness as quickly as possible."

After Chen Yuanguang finished speaking, Jiang Zhonghua and Wei Rongzhao's eyes lit up and they waited for Chen Yuanguang to give them a lecture.

Wei Rongzhao even saw the shadow of his mentor in Chen Yuanguang, and the master's demeanor was clearly visible.

The class lasted five days. In order to take into account their level of acceptance, Chen Yuanguang did not set a fast pace. It was not that they did not work hard, but there were too many cutting-edge things to catch up on. Chen Yuanguang might have just mentioned a term by accident, but for them, they had to read literature until three in the morning for this term.

When it comes to the design of piezoelectric material patch structures, the large amount of topological content makes them even more miserable.

So much so that Jiang Zhonghua privately complained: "I think we should find an expert in topological fluid mechanics? I feel like my CPU is going to explode."

Jiang Zhonghua was the one with all bald hair. He was still in the mood to make jokes. Wei Rongzhao felt even more miserable. "I have collected this last bit of hair with great difficulty. I guess it will all fall out after the classes are over in the next few days."

A week later, Director Zhao came to pick them up and talked to each of them in the conference room: "Professor Jiang, you should be aware of the importance of this technology?"

Jiang Zhonghua nodded. He was selected after going through layers of review and his reliability was very high.

"You will need to change your job later. Someone will contact you and you will need to start your new job immediately. The contact person will handle some trivial matters for you."

Jiang Zhonghua nodded: "Okay, I understand."

Director Zhao asked again: "What do you think of Academician Chen?"

Jiang Zhonghua knew what the other party was asking, thought for a moment and then said: "Academician Chen is definitely a master in the field of materials science.

He has a wealth of cutting-edge knowledge on various forms of materials such as condensed matter physics, magnets, crystals, etc., and has some knowledge of the underlying principles. Even among the masters, he should be the one with the broadest knowledge.

More importantly, he is able to put cutting-edge knowledge into his knowledge framework system and then output new content.

This can only be achieved when one has mastered this knowledge to a certain level. As for his attainments in mathematics and physics, I have no idea how profound they are. "

Jiang Zhonghua sighed after he finished speaking: "People are different after all, although I cannot understand why Academician Chen's scientific research results are so rich.

I saw some self-media on the Internet saying that Academician Chen had obtained alien technology. I had similar suspicions before, but after dealing with Academician Chen, I no longer think so.

Because his knowledge does not go beyond the existing theoretical framework, I know what each point is, or I can find the source, but we have never thought of using it in this way in the past.

My judgment is that Academician Chen is the most outstanding genius I have ever met.”

Director Zhao did not comment after listening: "Okay, I understand, remember the confidentiality agreement."

This has become a routine action in the past two years. Every scholar who collaborates with Chen Yuanguang will be asked this question.

Because the results were so astonishing, there were various opinions in Yanjing. Some people wanted to protect Chen Yuanguang, while others wanted to drain the pond and find out the source behind it.

The latter felt that Chen Yuanguang's scientific research results violated objective laws and did not believe that a person could be so talented.

"We will stand firmly with America." Neon once again emphasized its past arguments.

At this critical juncture

"Is Kishida crazy? Has he started to do whatever it takes to keep his position?"

A large number of opposition voices flooded Japan's major social media platforms, and Kishida's approval rating hit a new low.

In such an environment, a military industry exhibition was quietly held in the western part of Shudu.

"Aren't we making dumplings just for the vinegar?"

"That's right, but now this dish of vinegar is valuable, so shouldn't we release it to scare them?
If we don’t scare them, what will happen if Japan really meets its end?
The Americans are gone, and the domestic and international situations are now very good. Europe and we are in an unprecedented honeymoon period, and we have a large number of cooperation projects in trade and scientific and technological research and development.

If the Americans really force us to back down at this time, we will be dragged down by them.

This good situation will soon be ruined.

The EU is not as obedient as the 4Vs. The US is worried that there is no reasonable way to prevent the world's major economies from trading with us.

We can’t give them a chance to talk at this time.”

"But can this new 039C scare Japan?"

“Whether it works or not, you have to give it a try.

The 039C is not the key. The key is to make them realize that as long as we are given time, we can drive the submarine to their coast without being discovered by them and launch a missile at Tokyo.

To be honest, from this perspective, I am actually looking forward to the fight.”

"There's nothing I can do. The big guys don't want to fight. Your will is useless. I also want to see 4V get beaten. Why don't you beat this rebellious son now?"

The core purpose of the Shudu Military Industry Exhibition is to showcase the new 039C stealth conventional submarine designed based on new piezoelectric materials.

Although it has not yet been officially put into service, according to the progress, the first new 039C will definitely be put into service by the end of this year.

Therefore, it is not too early to exhibit now.

The Shudu Military Industry Exhibition invited participants from more than 50 countries around the world, mainly from Asia, Africa and Latin America.

Just when everyone thought that this time was no different from the previous ones, the China Shipbuilding booth was crowded with people.

Because in the center of the China Shipbuilding booth there was a brand new submarine, with the logos of China Shipbuilding and Guangjia Aerospace placed next to it.

And the parameters clearly state: noise decibel level is 12dB at a speed of 50 knots.

This resulted in the booth being filled with foreigners, all of whom were discussing the authenticity of the matter.

The difference in appearance of this submarine model is also obvious to everyone.

"Oh shit, the Americans are going to have trouble sleeping.

A submarine with a sound level of 50 decibels will have its sonar completely ineffective."

Generally speaking, the background noise of the ocean fluctuates between 100 and 110 decibels. The noise of the federal nuclear-powered submarines is about 110 decibels, and the noise of China's nuclear-powered submarines is 160 decibels. In recent years, the noise of conventional-powered submarines has been reduced to 110 decibels for the first time.

Simply put, reducing it to 110 decibels will make the submarine difficult to detect.

Once it drops below 70 decibels, it will be almost impossible for sonar to detect it, and at 50 decibels, all existing sonars will be eliminated.

"Are the Chinese using this method to warn the Federation and Neon not to act rashly?"

"Although I know that the Chinese have made rapid progress in technology in recent years, is 50dB too advanced?"

"It looks really nice, can we buy it?"

(End of this chapter)