Siheyuan: I eat melons while doing scientific research

Chapter 1209 I haven't even started yet, can you tell me there are 4 types? (4k)
"Notify our comrades in Cape City. No matter where the drone we just shot down lands, bring all the debris we can find to the capital as quickly as possible. Don't let go of even a single screw!"

This is the army side, which received the request from the Defense Work Committee.

Comrades in the army are happy to see this. As we all know, we are becoming more and more skilled in "saluting" advanced weapons and are reaping more and more benefits.

"Okay! Don't worry, even if it's just a piece of paint, I will ask the comrades over there to get it to you intactly! Not only the main body, but any fragments that can be found, let alone if they fall on the ground, even if they fall into the sea! I will fish them out for you!" The comrades in the army laughed happily.

The location where the enemy plane was shot down was just above the coastline, and there was no guarantee that some debris might have fallen into the sea.

"That won't be the case. Forget about the sea. The sea there is quite deep. Otherwise, we wouldn't look down on that place. If some debris falls into the sea, we'll just wait and fight. Imperialism is still determined to destroy us, and they will definitely come again." The Defense Committee was afraid that the troops were really that angry, so they quickly reminded them.

Before the discovery of oil and gas, the reasons for keeping a close eye on the southern waters were, first, fisheries, and second, that it was deep enough.

As for shipping, oil and gas and the like, they are still at the back.

However, according to current salvage technology, it is really difficult to salvage from places that are too deep.

"Don't worry about it. Anyway, we will get this thing to you as intact as possible." The comrades in the army had their own ideas.

No matter how enthusiastic the troops were, it would still take some time to pack and transport the goods. Most importantly, Cape City was on an island! This meant that extra time would be required for transportation, and it would take more than two or three days.

At the same time, in a place on the northeast coast, several comrades met together and looked at an excerpt of a meeting record in their hands. They thought as they read, but their brows were never relaxed.

"This record has no beginning or end. I'm a little curious about what's at the beginning and the end." A comrade said with a smile.

"What are you thinking about? You want to make a mistake, right? Okay, okay, focus on what we have in our hands." said another one.

"The submarine anechoic coating, I seem to have heard of this thing somewhere, but we have not conducted any similar research, and the technology supported by Big Brother so far does not include any such technology." said a comrade.

Big Brother is still researching his own things based on Hans' technology in S2. Firstly, the technology is not that good yet, and secondly, even if the technology is good, it is impossible to provide support casually.

Whether it is the Russians or the Americans, the confidentiality of this thing is very high. This is mainly because they suffered enough from the Hans U-boats during the S2 period. After the S2 period, with the maturity of nuclear missiles, the importance of submarines has been sublimated again.

To be honest, the Russians have done a good job by supplying us with the full set of technology for conventional-powered R-class submarines. In this regard, we have to admit that the Russians are still generous.

However, these things cannot change the current situation where several comrades here can't find where to start with this thing.

"I've heard of what you're talking about when I was abroad. It's a material invented by Hans during S2. It seems to be called Alberich. But the performance of this material is actually average and not very useful. I haven't seen foreigners pay much attention to it."

Upon hearing this, it was obvious that this comrade had originally studied and worked abroad, and after the founding of the People's Republic of China, he was inspired and happily returned to participate in the construction of the country.

Alberich, Hans invented the earliest sound-absorbing covering material during the S2 period. It can only be said that he was indeed a pioneer. As for performance, it has it, but it is not very useful.

"How common?"

"According to the test results I have seen, its main sound absorption frequency band is between 9k and 18kHz, and the sound attenuation is only a few dB, and the effect on low frequencies is extremely poor."

Alberich, thickness 30mm, with a cylindrical cavity of 2~5mm diameter on the side facing the steel plate.

The Alberich material here refers specifically to the material invented by Hans, which is different from the "Alberich-type material" mentioned later when studying sound-absorbing materials.

Since the covering layer is added after the submarine is finalized, the thickness of this thing cannot be made larger. However, thickness is an important parameter of the anechoic tile.

So the effect of this thing is pretty much just that, and its problems don't stop there.

"The low-frequency effect is poor? That's indeed not very good." Low-frequency sonar, an important detection method, is used to deal with submarines with excellent silent performance.

In fact, many principles in the world are the same. To deal with stealth aircraft, long-wave radar is used, and to deal with stealth submarines, long-wave sonar is used. Comrades who have studied physics know that long wave = low frequency.

"But at least it proves one thing, that this thing really works?" Another comrade had a different starting point. Don't worry about whether it's good or not, just tell me whether it works or not.

As for the poor results, it may be because the technology is not yet up to standard. We just need to study it slowly.

"Hey, you know what, your perspective on the problem really makes sense!" The comrade who returned from abroad laughed and said, "After I got this record, I also did a preliminary analysis of the water sound. Obviously, this Alberich uses an acoustic resonance cavity to absorb vibrations. But this is also the problem. The sound absorption frequency band of this principle of sound-absorbing materials depends on the size of the resonance cavity. So Alberich's sound absorption frequency band is 9~18kHz."

This overseas returnee comrade obviously has a lot of intentions. Although he was unable to participate in the research due to his status limitations, he still has the basic skills and has memorized a lot of things.

Another comrade was delighted when he heard this: "Then why not just use a cavity diameter that can match the low frequency?"

A comrade who knew Alberich a little shook his head and said, "It's not that simple. In principle, the longer the wavelength, the larger the diameter required. The diameter of the resonant cavity that can handle sound waves below 1kHz is already so large that it will destroy the stability of the cavity. Moreover, the thickness required by the diameter is unbearable for submarines."

As soon as he finished speaking, another comrade added: "Well, he has a point, and this does not solve the problem that the resonant cavity can only cover a specific frequency band. If you want to achieve broadband coverage, you have to make holes of different sizes in the covering material, which is problematic in engineering implementation. Both horizontal and vertical arrangements have problems. In the end, it can only solve the sound absorption capacity of a few specific mid- and high-frequency bands, which is not very meaningful."

Comrades all have a very deep knowledge of acoustics, and after careful analysis, they found that this is indeed the case.

After thinking about it, I decided to find the person who tied the bell to untie it. This place is not far from the capital, so I'll go find someone!
In the past few days, Gao Zhendong has been carrying out his daily work while waiting for the arrival of the drone wreckage. Along with the drone wreckage, there should be comrades in China who are engaged in converting the Z-5 fighter jets into drones.

Taking advantage of this gap, Gao Zhendong sorted out the two "knowledge fragments" of tactical missile design overall and radio proximity fuze anti-interference technology, and sent them to the Defense Work Committee, which was responsible for distribution and he no longer had any responsibility for it.

He was still waiting for the fire bee, but someone came to see him first, and in a hurry.

Gao Zhendong could even tell that the visitor's confidentiality level was not much lower than his own. Of course, it was difficult for it to be higher than his. However, although the visitor's confidentiality level was high, it was estimated that he had made sufficient preparations and relevant approvals before coming, and he got straight to the point as soon as he arrived.

"Chief Engineer Gao, we are here this time because of the issue of submarine sound-absorbing materials. My surname is Hong, and I am specifically responsible for this project." Engineer Hong introduced himself and stated his purpose, while marveling at this destination that he had to go through a lot of procedures at the Defense Work Committee to find.

The Seventeenth Ministry of Machinery? Yes, this place is made of dry materials, and sound-absorbing materials are also materials, but when I think about it carefully, I always feel that something seems wrong.

The young age of the person opposite him surprised him even more. However, the Defense Work Committee only said that this comrade was a chief engineer and did not introduce anything else.

But at least there is one thing that comrades know, this comrade's name sounds familiar, I have heard it in the newspaper, there are too many people with the same name and surname. It seems normal to think about it, Gao is not a small surname, and because of the founding of the country, many people named or changed their names to "Zhendong".

It's like shouting "Wang Gang" on the street, a lot of people will turn around, and some of them may even have just returned from Siam.

Gao Zhendong was very enthusiastic. Submarines, anechoic tiles, it was rare for him to see someone who worked on these things.

To be honest, apart from Miss Qiu's family, submarines are the most mysterious. He has met many comrades who are engaged in ballistic missiles, but this is the first time he has seen a submarine.

After the first time, there will be more later, Gao Zhendong thought happily.

"Welcome, welcome. Comrades, are you here for the silencing tiles this time?"

I guess there are some difficulties with the sound-absorbing tiles, but I don’t know what the specific difficulties are yet.

Engineer Hong smiled and said, "That's right. I'm ashamed to say this. We just received a task from the Defense Work Committee and the Marine Equipment Bureau not long ago, requiring us to develop submarine sound-absorbing covering materials. But to be honest with you, Mr. Gao, we really don't have any foundation in this area, and we still feel we don't know where to start. So, I came to ask you for advice."

Silencer tiles, the name given by Chief Engineer Gao is very appropriate.

Mr. Hong is very direct, and there is nothing to hide.

"Oh, that's what happened. Can you tell me more about it?"

"Okay, now the situation is like this..."

Listening to Engineer Hong's description, Gao Zhendong knew that there was a job coming.

This thing is really a niche, but also very important. It is one of the important means of submarine stealth. Unlike float valve seismic isolation, this thing has very high theoretical requirements. If float valve seismic isolation can be exhaustively studied through engineering experiments, then this thing is not so easy to exhaustively study without theory.

Take the Americans and the Russians for example. They took over the Alberich research results from Hans in 45, but they still haven't figured it out. The Russians used it for the first time in 1965, and the Americans used it even later, in 1988.

Considering the high importance and obvious effect of this thing, which is simply the stealth coating of submarines, Gao Zhendong did not hesitate to use a full network search opportunity. After all, aircraft can influence the direction of conventional wars, while submarines can determine the strength of nuclear deterrence.

There are only two times left, Gao Zhendong feels a little painful but thinks it is worth it. The main reason is that this thing has nothing to do with the inland province of Qianshan, otherwise he could save some money.

Originally, Gao Zhendong did not hold out much hope. He just hoped to find some review papers or introductions to point out the direction for his comrades. However, he never expected that there would be a monograph on this thing!

grass! grass! grass!
Gao Zhendong even thought of the C language in his mind. He had found a treasure!

As Mr. Hong was narrating, Gao Zhendong quickly glanced through the introduction of the book and then asked a question that left his comrades dumbfounded.

"Are you working on decoupling tiles, sound-isolating tiles, sound-absorbing tiles, or damping tiles?"

These four types of tiles are the classification method of the Citigroup guys, but technically speaking, this classification method is indeed very scientific, and good things should be used. Among them, sound insulation tiles are also called transmission loss tiles in some materials, and sound absorption tiles are also called anechoic tiles. The former of these two naming methods is intuitive, and the latter is scientific.

These four types of tiles have different properties, materials, and structures and can be used in different occasions.

This time it was Engineer Hong's turn to think of C language in his mind. I haven't gotten into the state yet, my mind is blank. You tell me there are actually four types of this thing?

"Uh... Chief Engineer Gao, to be honest, we haven't done that much research yet. We're not even sure where to start with the sound-absorbing tiles." Engineer Hong suppressed his surprise and answered honestly.

Gao Zhendong patted his head, feeling dumbfounded. This classification only appeared in the 80s. For today's comrades, it was indeed a bit ahead of its time.

"Oh, it's my fault, it's my fault..." Gao Zhendong's words made the comrades feel refreshed. This Chief Worker Gao was quite nice. He did not blame us for our lack of ability, but instead blamed himself for not thinking things through.

While his comrades were thinking this, Gao Zhendong explained the classification and differences of the four types of tiles one by one.

"Considering the complexity of water noise, it is difficult to use one type of sound-absorbing tile to solve all problems. Therefore, given the difficulty in realizing multifunctional composite sound-absorbing tiles, I considered dividing the sound-absorbing tiles into the above four types..."

With Gao Zhendong's introduction, the comrades led by Hong Gong felt that the door to a new world had been opened.

Sound-absorbing tiles are used to protect active sonar. They cover the surface of the submarine to absorb the sound waves of the active sonar.

Sound-proof tiles are mainly used to isolate the noise inside the submarine and prevent it from being transmitted to the outside. They also have another function, which is to isolate the noise inside the submarine from the submarine sonar to avoid affecting the submarine's sonar.

Damping pads are used on the outside of mechanical compartments with strong vibrations to absorb vibration energy and reduce the noise radiated outward. What they absorb is direct vibration, not sound. Of course, to some extent, vibration is also sound.

Decoupling tiles remove the coupling of sound and vibration inside and outside the submarine and reduce the outward radiated noise. They have the characteristics of both sound insulation tiles and damping tiles.

(End of this chapter)