Hammer of Technology

"Well, I just arrived 5 minutes ago. Seeing that you are busy, I didn't bother to call you." Lu Dongyi nodded, and he was already used to the "no one" who didn't care about Ningwei anyway.

In fact, he himself is the same. When thinking about problems, he often ignores what happened around him, which is very easy to understand.He really doubted whether classmate Jiang could bear this kind of temperament that would be ignored from time to time.

After all, once people like them fall into a state of concentration, they often don't look like normal people.

"It's okay, just call me next time. I've agreed with Director Tian to report at nine o'clock. I'll go first, Brother Lu." Ning Wei said hello to Lu Dongyi, then stood up and prepared to talk to his brother. Instructor report.

"Oh! But it's already nine twenty..." Lu Dongyi looked at Ning Wei's standing back and said.

"Ah? It's okay, Director Tian doesn't care about these details." Ning Wei ran out of the office while speaking.

Lu Dongyi shook his head, probably because he was favored and confident, then lowered his head and focused on the direction he was researching, well, it happened to use Ningwei Space.

……

"Director Tian...how about I come back to you later?" When Ning Wei pushed open the door of Tian Yanzhen's office and saw someone already talking to Tian Yanzhen, he shrank his neck and said.

Tian Yanzhen glanced at his student and asked, "Didn't you say to come over at nine o'clock?"

Standing in front of the door, Ning Wei scratched his head and explained: "Yes, but I couldn't fall asleep after I came back yesterday, so I changed the program, and I just sorted out the data for half an hour, so as not to forget later, and finally sorted it out. I was so focused that I forgot the time..."

Well, this reason is invincible.

For an instructor, it is absolutely forgivable to forget time because of studying knowledge. Of course, there is a premise for using this reason, that is, as a student, you must first have results.And this piece happened to be Ningwei's longest board, nothing else, a bunch of achievements.

"Come in and sit down, let me discuss something with Professor Tan first." Tian Yanzhen pointed to the sofa in the office and said.

Lu Dongyi was right in thinking, those who are favored can indeed have nothing to fear.

"Hi, Professor Tan, I'm sorry to interrupt you." Ning Wei greeted Professor Tan honestly as soon as he entered the door.

"Haha, Ning Wei, I know you, you are our academician Tian's treasure, just now we were saying that our China Fields Medal 0 breakthrough may fall on you." Professor Tan smiled at Ning Wei Laugh, said politely.

"Old Tan, don't praise him. If you don't praise him, he's already drifting away. If you praise him, the earth won't be able to accommodate him. Ning Wei, this Academician Tan Dejie is the vice president of the school's School of New Materials and is a pillar. Many cooperation projects with the school and the Chinese Academy of Sciences were contacted by Academician Tan, and several key laboratories in the School of Materials Science and Technology were established under the leadership of Academician Tan." Tian Yanzhen introduced a sentence.

"Academician Tan is really amazing!" Ning Wei praised sincerely.

Well, I just came here to report a job, and I met another academician, which only made Ning Wei think that Yanbei University was really a hidden dragon and a crouching tiger.

"Haha, don't listen to your director Tian bragging for me. I am so good that I came to your old Tian for help? Are you indirectly promoting yourself?" Tan Dejie smiled and said.

"Help? Academician Tan, did you encounter problems with your project?" Ning Wei, who sat on the sofa, couldn't help but ask.

"Well, I have a project in cooperation with the National Physical Laboratory of Condensed Matter. It was going smoothly, but I encountered some difficulties in the closing stage. I need a Ph.D. who is proficient in group theory and tensor analysis or The professor went to help us do some calculations on the laboratory data to see if we could find the problem through mathematical analysis. This is not the first time, and your director Tian has given our laboratory a lot of support in this regard." Tan Dejie laughed explained.

When Ning Wei heard this, he suddenly thought of March.

Then he looked at Tan Dejie eagerly and said, "Hey, Professor Tan, speaking of it, I happen to understand a little bit about group theory and tensor analysis!"

Before the astonished Tan Dejie could answer, Tian Yan, who was sitting behind the desk, couldn't help it: "Ning Wei, have you been free recently? Your top-notch project application has just come out, and you have time to research materials ? Besides, your major is not group theory and tensor analysis? What's the matter?"

Ning Wei looked at Tian Yanzhen and argued, "You can't say that, Director Tian, ​​although I haven't studied tensor analysis, I'm good at differential geometry. The form is expressed in the form of tensors, and I am familiar with partial differentials! As for the concept of group theory, it is too big, but brothers often ask me to help them solve problems that need this.”

"And don't worry about top-notch projects. I have roughly set up the outline, and I can just add content later. To tell you the truth, I am not interested in materials science, but I am really interested in materials science models recently. I'm interested, maybe this time I can verify something."

What Tian Yanzhen said stunned him.

It is no exaggeration to say that Ning Wei almost cast a psychological shadow on him as a mentor.

Generally speaking, most of the PhDs under him are more resistant to this kind of secondment to do laboratory work, not to mention wasting time, and the results made do not belong to them, and they all avoid it.More importantly, this kind of thing is often purely helpful. When you meet a polite professor, you can give some rewards after the project is completed. When you meet a less polite professor, you often just say thank you.

Of course, whether there is a reward or not is sometimes related to the contribution of these PhD students in mathematics who help in the research process. Sometimes it is because some paths in the laboratory are not going to work. I hope to find a new path through mathematical analysis. If successful, It can often show its effect; but sometimes it is only possible to reduce the workload of the laboratory through mathematical modeling. At this time, it is difficult to define its contribution to the entire project.

If the project fails in the end, maybe it will be a mess.

Didn't you see that every time you ask someone for help, a dignified academician always comes to your door with various high hats and soft words to ask for help?If it's really a good thing, it's impossible to come directly to the door, it's just a phone call, and the staff will arrange it...

In short, this was a thankless task, Tian Yanzhen had no intention of letting Ning Wei go into this muddy water at all, but the little guy got so excited that no matter how hard he winked, it was useless.

"Haha, Xiao Ning is really enlightened. Now that you say that, I'm counting on you! Haha, Lao Tian, ​​you are so kind. I came here to ask for help, and you sent the strongest child under your command to help. This way, the project is a success. Invite you to dinner, the place is up to you. But Ning Wei, this project is a bit rushed, can you coordinate it?" Tan Dejie didn't wait for Tian Yanzhen to speak and object, and said with a smile.

"Wait... Ning Wei, are you sure you want to help? Let me tell you first, Professor Tan has elite troops under his command. The problems they encounter in the laboratory are often very difficult. Ah. And most of the time it’s temporary difficulties, maybe before you have time to play a role, people can solve the problem by themselves. But it’s not as challenging as you think.”

"And didn't you just establish a relationship with that classmate Jiang from the School of Economics recently? You don't need more time for yourself? Let me tell you, projects that are in a hurry are the most time-consuming. When the time comes, the laboratory will answer the phone call." A phone call can make you doubt your life."

Tian Yanzhen said.

There is no way, my lover hurts himself.

Originally, he was thinking that Ning Wei could study mathematics well during the most golden period of his life. Who would have thought that this guy is obviously talented in mathematics, but his interests and hobbies are obviously too broad.

People can spend a lifetime of energy just studying one branch of mathematics, but Ning Wei's interests are all over the branches. For example, he really never thought that Ning Wei even dared to speak a little bit about the extremely professional tensor analysis. ...

"Haha, Director Tian see what you said, do it, let me make a statement here today, if this project is successful, I, Tan Dejie, must give Dr. Ning a credit! Of course, the project is really in a hurry, Otherwise, there is no need for Xiao Ning to support, but the laboratory works flexibly, as long as Xiao Ning copies the data, the analysis can be done anywhere."

"In school, isn't dating supposed to be taking your girlfriend to do self-study together? She learns from her, and Xiao Ning analyzes our data. After dating three or five times like this, not only the love will be sweeter, but the project will also become more sweet." By the way, it’s done, isn’t it more romantic than cuddling at Weiming Lake? That’s okay, it’s decided, Xiao Ning, give me your phone number, and talk to Director Tian first, I’ll find a doctoral student to come over this afternoon I will contact you and take you to our laboratory for a first visit. I am very optimistic about you, doing mathematics is to be applied to various fields!"

Speaking of not giving Tian Yanzhen a chance to object at all, Tan Dejie left Ning Wei's phone number, then greeted Tian Yanzhen with a smile, and then walked away, leaving space for the master and apprentice.

Then Tian Yan broke out unexpectedly: "Ning Wei, tell me if you are free? I imply that it is so obvious that you still don't understand? Did you see Professor Tan Dejie smiling at you all the time? Look It’s easy to talk up there? Let me tell you, it’s all an illusion! When you enter the laboratory, you’ll know that the laboratory is not going well, and that guy can turn into a dynamite bag in a sudden transformation, whoever scolds him! He won’t I wonder if you are going to help!"

"Why are you rushing for such an errand? Is your project not important? The big data basic theory project you said has just started, and there are only phased results. What's wrong? This project is not busy enough for you? If you are so energetic , in your free time, you continue to advance the NS equation, you go to study the Riemann conjecture, you are not interested in the Riemann conjecture, to study Hilbert's 23 problems, you can always find what you like? You put Euler It’s okay to prove the irrationality of constants! Why did you go to the muddy water of other people’s materials laboratory?”

"Well, I'll call your Senior Brother Zhou later, and leave this task to him. You can do your research quietly, and you have to give a result within a year for the top-notch youth's project. I beg you, don't wait a day Is it okay to focus on some messy things at night?"

Well, it seems that Lao Tian is probably really angry, but Ning Wei thinks it's not a big problem.

"Director Tian, ​​don't worry, I won't be able to take advantage of them this time. We are the ones who take advantage of it. Think about it, I'm just going to get the data obtained by other people's laboratories for free to verify my ideas. If I really do my best, I will give you Save face; if something goes wrong, I will be scolded at worst, and I am the most resistant to scolding! And I believe that academician Tan must have reserved enough time for the project team, and will not really wait I was in such a hurry that I came to ask for help!"

Tian Yanzhen blinked, looked at Ning Wei, and asked: "Okay, then tell me, what idea do you need to verify with the data in their material laboratory?"

Ning Wei replied honestly: "To test a program's ability to process similar data, Academician Tan said that it is necessary to perform tensor analysis on laboratory data to find abnormalities. In fact, it is to find abnormal points from the big data model. Almost, they are all questions about the basics of mathematics. You don’t know, I often feel sleepy when studying pure mathematics recently, and when I look back, I will definitely dig out Hilbert’s 23 questions and study again.”

Tian Yan was really speechless, he almost forgot why he asked Ning Wei to come here...

Oh, by the way, it seems that he is asked to make a report, and then type a few sentences so that he can spend more time on mathematics research, less time to think about other messy things, and think carefully before speaking. Now he can't even listen to Ning No mood to report.

Being sent by Old Tan, I'm afraid it will be a waste of another month, and then the little guy in front of me is still happy, and I don't know who will take advantage of whom in the end...

"Okay, okay, you have to go, but since you took the initiative to accept this task, you still have to do your best, so as not to help, there are still a lot of empty talk!" Tian Yanzhen waved his hand.

He found that every time he saw Ning Wei, he was both proud and tired.

Needless to say, the reason for the pride is that students who can earn face after being released are always rare to meet, and the tiredness is that this guy is obviously full of energy and math talent, but he is unwilling to put all his energy on pure In the study of mathematics...

When did pure mathematics become so useless?Studying pure mathematics made him sleepy?Is this so human?

"Don't worry, Director Tian, ​​don't worry, I will definitely do my best. If this project fails in the end, it must be because of their problem with the direction of this project. It must not be that we failed to help!"

"Okay, you go get ready! That guy said it's afternoon, maybe he will send someone to arrest you and take you to the laboratory later! After you experience it once, you will know that there are some things that don't need to be so active." Tian Yanzhen Said angrily.

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172 New thermoelectric materials

Tian Yanzhen's judgment was indeed correct, and Ning Wei's phone rang before it was afternoon, before 10:30.

"Hey, Dr. Ning, my surname is Zhang, and my name is Zhang Yancheng. I am a student of Professor Tan. Director Tan asked me to pick you up to the laboratory. By the way, I will introduce our project to you. I am already at the gate of your research institute. Now, are you free now?"

"Okay, Brother Zhang, please wait for 2 minutes, I'll come out right away." After hanging up the phone, Ning Wei greeted Lu Dongyi again, and left the research institute. Sure enough, a big brother with glasses was at the entrance of the research institute He looked down at his phone.

The reason why Ning Wei thinks this is the big brother is that his face is really mature when he lowers his head, his eyebrows are raised and pulled downwards, and he looks miserable when he looks at it.

"Senior Brother Zhang?" Ning Wei called out.

"Oh, Dr. Ning, I'm sorry, I'm looking at a set of data just sent to me." The old man raised his head and slipped the phone into his pocket, reaching out to Ning Wei enthusiastically.

After shaking hands with this sad-looking Senior Brother Zhang, Senior Brother Zhang immediately said: "Let's go to the laboratory quickly, I will introduce the project to you on the way, and when I arrive at the laboratory, I will explain the general situation to you. The data has been copied, and you can bring it back later. However, because this project is originally a cooperative project, all data in the laboratory must not be made public until the paper is issued."

Ning Wei nodded and said: "I understand this, the principle of confidentiality, many of our research results cannot be disclosed to the public before they are published. I heard that you have to upload the preprint of the paper to arxiv before publishing the paper. Right?"

As he was talking, Ning Wei found that this senior brother Zhang walked almost like a race walk, and he couldn't keep up with the rhythm if he slowed down a bit.

"That's right. Now that the material is made and the direction is determined, those things can be studied. If you don't pay attention to it, people will restore the results and come up with a complete laboratory report from beginning to end. Who can ask for an argument? And Dr. Ning You don’t know, it’s hard to get materials, we’re pretty good, and most of the boss’s projects are relatively high-end projects.”

"You don't know, we next door are researching new energy batteries, making catalysts, washing bottles for several hours a day, and the battery parts are not seen at all, and we deal with various chemicals every day. Tell me, this kind of achievement If you are really plagiarized by your peers, do you want to die? It’s better for you to study mathematics! I just don’t have that brain, otherwise I will definitely go to the math school!”

Senior Brother Zhang sighed.

Well, each profession has its own hardships. Ning Wei actually wanted to talk to this Senior Brother Zhang about the hardships of learning mathematics, but he thought that he seemed to have no position to talk about it, so he gave up and put the topic on the right track: "Senior Brother Zhang, Professor Tan This project is a cooperation between your laboratory and the National Physical Laboratory of Condensed Matter? What exactly does it do? What do I need to do? Listen to you first, so I can make preparations."

Zhang Yancheng replied: "Well, our project is to use carbon nanotubes as hot-spot materials. Specifically, we use oriented nanotubes to produce a macroscopically weavable fiber. We hope to make a textile thermoelectric generator through it. The specific situation That’s right, a previous experiment in the physics laboratory unexpectedly found that the high power factor of a single nanotube can still be maintained after the macroscopic assembly of carbon nanotubes.”

"Before this, it was generally believed that it was difficult to achieve this, mainly due to the poor shape of the sample of carbon nanotubes and the lack of proper Fermi energy tuning. But after that experiment, the physics laboratory believed that carbon nanotube fibers could With ultra-high electrical conductivity and thermal conductivity, it can have a very high zt value and become a nearly perfect thermoelectric active cooling material. After all, compared with traditional materials such as bismuth telluride, lead telluride, and silicon germanium alloys, carbon Nanotubes are more environmentally friendly and have abundant reserves, so our boss went over to talk about it, and the two sides hit it off and started this project.”

"Oh!"

Ning Wei nodded, and then asked again: "But last time I really wanted to read an article, saying that if carbon nanotubes want to maintain the performance of the nanometer level to the macroscopic scale, it is still a problem in the current situation. It's very difficult. The laboratory preparation method can't be used for industrial mass production at all, so even if you really prepare this material, it seems that you can't use it now, right?"

This question obviously embarrassed Senior Brother Zhang beside him. He subconsciously raised his hand and touched his nose, explaining: "Ahem, what should I say about this, or how can I say it is research on cutting-edge materials, although it is definitely not necessary for the time being." However, it is placed there as a technical reserve, and when the industrial base develops in the future, this kind of aligned carbon nanotube material with macro-scale properties can be produced, and it can be used immediately.”

Well, Ning Wei decided not to care about the application anymore, and continued to ask: "Then what's wrong now? Do you need my help?"

"That's right. In order to find this material, we have screened out four samples representing the density of states of carbon nanotubes, including inner-wall semiconducting carbon nanotubes, inner-wall metallic carbon nanotubes, outer-wall semiconductive carbon nanotubes, and outer-wall metal carbon nanotubes. Carbon nanotubes. First of all, we need to do optical spectroscopic measurements, but the size and absorption of carbon nanotubes are more suitable for optical measurements than the fiber state."

"So we used a simple blade coating technique to produce aligned carbon nanotube thin films for optical measurements. Herein lies the problem. We started by dissolving carbon nanotubes in CSA using solution spinning and then produced thin films. This The process uses the same nanotube raw material and ensures that the chemical treatment is exactly the same as that of the fiber, including csa concentration, doping and annealing conditions, etc."

"But when we calculated and obtained the results based on the spectral measurement and absorption data brought into the previous laboratory data, there was a huge gap with the theoretical model we had previously determined. The same experiment has been carried out seven times, and the obtained The deviation between the results and the theoretical model has always been unacceptable. So we need a mathematician to integrate the existing data and help us find out where the problem is. It is convenient for us to adjust and improve the direction of the experiment. "

Brother Zhang briefly introduced the situation.

Ning Wei nodded and calmly experienced the experience of the brain acting as a translator, specifically translating the professional terms in Zhang Yancheng's mouth that should have been interlaced like mountains into various methods in the laboratory one by one.

Although it can't be said that Ning Wei can make up the whole laboratory process, at least he won't be ignorant of what he did in the laboratory.

"Oh, what's the annealing temperature?" Ning Wei asked casually.

In fact, these data are not related to his work for the time being, but walking on the road without talking about anything seems a bit monotonous.Moreover, Senior Brother Zhang obviously didn't intend to appreciate the surrounding scenery.

This question made Zhang Yancheng look at Ning Wei in surprise. After all, the borrowed mathematics doctors in the past were full of various mathematical formulas, and they were not very familiar with some engineering terms, let alone their experimental process. interested.

"The annealing temperature is the data given by the laboratory over there, and it is divided into two batches of 500c and 350c." Zhang Yancheng replied.

Ning Wei thought for a while, and then asked: "I remember that this type of thermoelectric material needs to increase the zt value. If I remember correctly, the formula should be zt=s^2tσ/k, right? In essence, what do you think This combination of carbon nanotubes should have a higher Seibel coefficient, higher electrical conductivity, and lower thermal conductivity, right? So what exactly doesn’t fit your pre-established theoretical model?”

"Have you ever studied thermoelectric materials?" Zhang Yancheng blinked and slowed down subconsciously.

After all, Ning Wei's achievements in mathematics and computer algorithms are too high. Even if he doesn't major in these majors, even if he spends every day in the laboratory, he will inevitably hear the legendary story of the young man in front of him every day.

In less than a year as a senior, he published six top journal papers. This efficiency can definitely make any academic person feel incredible.Moreover, one of the papers made a generation of famous mathematicians hate the hospital, one paper found a new way to solve the world's problems, and the other three papers directly involved an algorithm that could change the world. Now that the laboratory is on a business trip, air tickets are easier to book than before. I have to thank this young man in front of me.

And now he can still talk to him about material science, is this a monster?

"Hehe, Senior Brother Zhang, to tell you the truth, I just understand a little bit. I have read a few articles casually, so I dare not say that I have studied it." Ning Wei replied quickly.

"Oh, I understand a little bit."

Zhang Yancheng nodded suddenly, and then explained: "Well, the problem actually lies here. In theory, you are right. Many previous researches on traditional thermoelectric materials have improved the zt value by reducing the thermal conductivity. , but we think it is more important to improve the power factor. This is the innovation point of our project. We define the power factor as pf=s^2σ, so the larger the power factor, the greater the heat source, such as solar energy Or when industrial waste heat can maximize the output power density."

"Additionally, during the active cooling mode, the high thermal conductivity can utilize the Peltier effect to increase the heat flow rate from the hot side to the environment, which is promising in electronic thermal management applications. In this active cooling mode, the heat can be Pumping from the cold side to the hot side via the Peltier effect, the maximum hot-side heat flow in active cooling is proportional to the effective thermal conductivity k eff , which we define as k eff=k+pf?t2h2Δt, where th is the heat side temperature, Δt is the temperature difference between the two sides, so you get the idea? This shows that active cooling requires large k and large pf, not high zt!"

"Actually, the research on traditional materials has almost reached the ceiling. For example, bi2te3 and its alloys have shown extremely high performance. But those things are poisonous, and the raw materials are relatively scarce. It is very difficult to improve the stiffness; organic materials are also a direction, but we have also studied organic materials, and they are difficult to increase their pf value, so if our project can be successful, wait until the industrial base is improved to maintain the industrialization of carbon nanotubes with microscopic characteristics Once the mass production technology appears, it can be used in a wide range of applications immediately.”

Well, with an extremely detailed explanation, Ning Wei has roughly understood the meaning of this project and the material theory model that Senior Brother Zhang said.It is nothing more than improving the power factor and improving the thermal conductivity at the same time, not only pursuing a high zt value, but also making the zt value reach a certain advantage to meet the needs of the future thermoelectric material market.

The only thing that didn't explain was probably where the problem was. Fortunately, before Ning Wei could ask again, the laboratory building had already arrived.

The majestic cylindrical laboratory building is right next to the teaching building of the School of New Materials. Only then did Ning Wei realize that after coming to Yanbei University, he hadn’t really visited the school. For example, he had never been to the School of New Materials. Pass.

It was only after Senior Brother Zhang walked into the laboratory that Ning Wei saw the true background of the top universities in China.Under the introduction of Senior Brother Zhang, Ning Wei looked at the high-tech laboratory equipment displayed in various laboratories, such as differential scanning thermal analyzer, X-ray photoelectron spectrometer, and X-ray diffractometer, just like Grandma Liu entered the Grand View Garden. , atomic force microscope, specific surface area and porosity analyzer, micro-Raman spectroscopy measurement system, multi-channel electrochemical workstation, high-resolution field emission scanning electron microscope (sem), high vacuum coater, cutting and grinding machine...

Through Brother Zhang's introduction, he probably understood that the reason why Professor Tan often asks Tian Yanzhen for help is that there is a high probability that the use of the above instruments in various projects not only requires an appointment and application in advance, but also charges for the use of the project team, which does not sound good. too cheap.

For example, the cutting and grinding all-in-one machine school charges 500 an hour internally, and 600 an hour if it is external; another example is to use a micro-Raman spectroscopy measurement system for 300 an hour internally, and 400 externally. Less than 50, no less than 100 outside.

And it was different from Ning Wei's imagination. The entire project team was not busy in one laboratory, but divided into several laboratories. Brother Zhang was mainly responsible for coordinating the operation of the entire project team.

Think about it this way, in the seven experiments conducted before, four samples were prepared for various treatments in each experiment, and the time and money were spent like running water...

Although it is said that the money earned by the laboratory will definitely be used for equipment maintenance and maintaining the competitiveness of the laboratory, and the purchase of new high-end equipment according to the application, but for the project team, it is actually a settlement with money. If you want to see it, it really hurts.

Taking Ning Wei to learn about the various large-scale equipment in the laboratory testing center, Zhang Yancheng brought Ning Wei to the door of a laboratory: "We usually do things here, and all kinds of data are also stored here. computer."

"By the way, Brother Zhang, I don't need to come to the laboratory to report every day, right? Professor Tan also said that I can take the data to the research institute for analysis." Ning Wei said.

"Oh, it's okay, I brought you here mainly to show you our complete testing process, and then you can go anywhere you want to do calculations, but the time is very fast, it would be best if you can do it as soon as possible." Zhang Yancheng replied .

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173 Mathematics, omnipotent

Walking into the laboratory, Ning Wei's arrival did not cause any commotion. In fact, Ning Wei felt that everyone in the project team was depressed, like eggplants beaten by Shuang.

"Ahem, everyone, stop for a moment. Let me introduce you. This is the foreign aid that Professor Tan invited us. Everyone should know that Dr. Ning is a student of Director Tian of our Institute of Mathematics. Welcome everyone."