A genius? I just love studying.

Chapter 154 Model Improvement
Moreover, the emergence of high ZT thermoelectric materials will change chip architecture, making integrated optical-electrical-thermal chips possible. Thermoelectric materials can directly convert waste heat into electrical energy, which can be used by internal sensors or edge AI units of the chip, thus realizing energy closed loop.

With the widespread adoption of self-cooling chips, traditional heat sinks will be phased out, and the size of devices will be reduced to 1/5 of what it is now.

In the long run, this will directly lead to the development of quantum chips, which alleviate the decoherence problem of qubits, allow superconducting quantum chips to operate at higher temperatures, reduce cooling costs by 90%, reduce the power consumption of neuromorphic chips to the μW level, and support the long-term operation of implantable medical devices...

The future looks very bright!
Of course, when looking to the future, we must also look down at the road beneath our feet.

The reality is harsh. According to the information provided by Professor Xiao, the ZT value they can currently achieve is only 0.92. This is not a groundbreaking breakthrough, and it has not even reached the commercial standard of 1.5.

"it is good!"

Yang Chi nodded with satisfaction. He liked this efficient communication and was also pleased with Chen Hui's attitude. Even if someone's skills were slightly lacking, he would welcome them as long as they were willing to work hard.

"You should know that the formula for calculating the ZT value is (SσT)/κ. There are three main ways to prepare high ZT value materials: either by enhancing electrical transport performance through band engineering, such as band convergence and multi-valley effects to improve S and σ, or by decoupling electroacoustic transport through microstructure control to separate the electron and phonon transport paths. However, the first two methods are too difficult to implement. Even if high ZT value materials can be obtained, the cost of industrialization is too high, making it difficult to popularize."

"Currently, the main approach we use is to suppress heat conduction by reducing lattice thermal conductivity through nanostructures, defect engineering, or composite material design."

As Yang Chi walked, he explained, “What we want you to do this time is to use our experimental data to build a multi-scale model to quantify the contribution of nanodefects and dislocations to thermal conductivity. If you can find an algorithm or a multi-objective optimization method to balance the competing relationship between S, σ, and κ, that would be even better.”

After they finished speaking, they arrived at a desk. Yang Chi turned on the computer and said, "This is the data from the 27 samples we have collected so far. You can study it here or copy it back to your computer for further study. However, this data is confidential and please do not disclose it."

"clear."

Chen Hui nodded, his mind already absorbed in the data before him.

"Sigh, another failure."

Just as Chen Hui was studying the experimental data, a sigh came from beside him, "The grain boundary scattering model clearly predicted that the thermal conductivity could be reduced by 30%..."

Xiao Meng took off his goggles and looked at the ZT value calculated by the instrument next to him: 0.91, which was even worse than the results of their previous experiments. This was not scientific.

"I think there was a problem with our previous model."

Yang Chi approached Xiao Meng and looked at the synthesized sample in the experimental equipment in front of him. He said confidently, "Teacher, take a break first. We've invited a math whiz. If we can optimize the model, we should make some progress."

"How can I possibly rest?"

Xiao Meng shook his head. "The Huazhong University of Science and Technology next door also has a lab doing this kind of research. I heard they have made considerable progress. If we stop now and let them publish their results first, all our previous efforts will be wasted."

The world of scientific research is equally cruel. With so many researchers around the world, it's inevitable that they'll run into each other on research topics. This is true for mathematics, and it's also true for physics. If you're a step behind, you can lose everything. She doesn't have to think about herself, but also about the hard work that everyone in the lab has put in.

After she finished speaking, she subconsciously looked at Chen Hui. Without a doubt, Chen Hui was now sitting in a crucial position, carrying their hopes.

Physics cannot be separated from mathematics, but not all physicists are good at mathematics. Mathematics is not her strong suit. She found it quite funny that she, a professor, had to rely on an undergraduate.

"Don't let his youth fool you. He's already published a Q1 SCI paper and is a gold medalist with a perfect score in the IMO. His skills are definitely not bad," Yang Chi explained before Xiao Meng could speak.

“Our model is already quite perfect. Even if the professors from the School of Mathematics came, they probably wouldn’t be able to find a direction. Now we need a genius with strong intuition to find a way to improve this model. He is indeed a good choice.”

"hope so!"

She was the one who invited him, so of course she knew Chen Hui's resume. Xiao Meng stepped to Chen Hui's side and said, "Hello, I'm Xiao Meng. Welcome to our project team. We're counting on you from now on!"

Chen Hui looked up at the spirited young woman, surprised that Professor Xiao Meng, whom the teacher had mentioned, was so young. He nodded and said, "I'll try my best."

Xiao Meng nodded, "If you have any questions in the lab, you can ask Yang Chi anytime. He's in charge here while I'm not here."

Yang Chi was the first master's student she took on. He was highly trusted by her and also had strong research capabilities.

This is one of the reasons why she is so eager to produce results. Only if this project achieves a breakthrough can she be promoted to full professor and have a doctoral program, at which point she can directly take Yang Chi as her doctoral student.

Xiao Meng didn't say anything more. After working on experiments for several hours, she turned and walked out of the laboratory. She needed to rest.

Time always flies when you're focused on something.

"Let's go get something to eat first."

Yang Chi suddenly came to Chen Hui's side and reminded him.

Chen Hui then realized that it was already past midnight; he had been staring at those dozen gigabytes of data for more than three hours.

"it is good."

"Food is as essential as iron," Chen Hui said, and without refusing, he got up and the two walked together toward the cafeteria.

"Have you come up with any ideas?"

Yang Chi asked casually.

Chen Hui shook his head.

When Chen Hui saw these data, he suddenly realized the difference between scientific research and doing exercises.

Whether it's a competition or the college entrance examination, the questions have fixed solutions and answers. At the very least, the questions are clear, asking you to prove something or solve something.

But scientific research is not like that. Many times, you don't even know what the problem is. Even if you have the skills to slay dragons, if there are no dragons, what can you slay?

In many cases, there may not even be an answer, which is the most despairing thing. It is very possible that what you have studied for months or years is completely wrong and there is no answer at all!
Finding the path to truth in data of terrifying magnitude and vastness, like the starry sky, is not an easy task.

"It's alright. This isn't something that can be solved overnight. You can take a look at the relevant papers first. There are also recommendations in the materials we provided to Professor Yuan. Take it slow."

Yang Chi patted Chen Hui on the shoulder.

He was indeed very anxious, but he also understood that this couldn't be rushed.

Chen Hui, who had been pondering the problem, ate lunch hastily and headed straight for the laboratory.

"Aren't you going back to rest?"

With mixed feelings, Yang Chi asked, "Only by getting proper rest can you keep your mind clear and analyze problems better."

"You go back first, I'm used to it, it's okay."

Chen Hui rejected the other party's suggestion.

Seeing this, Yang Chi also turned around and returned to the laboratory with Chen Hui. The laboratory is different from the teaching and research office. Some instruments and materials are dangerous, especially since Chen Hui is a new recruit. If any safety accident occurs, he, as the person on duty in the laboratory, will be responsible. He didn't want that to happen.

He now regrets not insisting that Chen Hui copy the experimental data back for further study.

Stepping back into the lab, Chen Hui noticed that it was about 200 square meters. A small portion contained tables, serving as temporary workspaces for the researchers, while the rest was filled with various futuristic-looking experimental equipment. "This is a spark plasma sintering furnace, used to prepare high-density nanocrystalline thermoelectric materials, such as bismuth sulfide. It uses pulsed current for rapid sintering to reduce grain coarsening. The minimum power is 20 kW, the maximum temperature can reach 2200 degrees Celsius, and the maximum pressure is typically 20 tons..."

Seeing Chen Hui's curiosity, Yang Chi introduced it in great detail, "This is a medium-sized furnace, made by Chenhua Company in Shanghai, costing two million."

Chen Hui clicked his tongue in amazement. Good heavens, doing physics experiments is really expensive. It seems to be a completely different style from mathematical research.

"This is a hydrothermal reactor, used to control the phase transition of materials such as iodine-doped copper selenide, and to synthesize specific crystal structures under high pressure and high temperature..."

Over the next few days, Chen Hui worked from dawn till dusk, putting aside even his thesis and devoting himself entirely to processing experimental data and building models. During this time, he also observed Yang Chi and his team's experiments several times.

Everyone was very enthusiastic towards Chen Hui, which made Chen Hui feel a little embarrassed. Three days had passed, and he still had no ideas.

Over the past three days, he has not only been studying the data but also researching a lot of related materials. His proficiency in mathematics and physics has improved by 2% each, but he is still at a loss when it comes to the model.

The model used by Professor Xiao Meng's team is derived from the Debye-Callaway model. Its core idea is to treat phonons, i.e. lattice vibration quanta, as gas particles and calculate thermal conductivity through statistical scattering events.

They made two corrections, introducing the grain boundary scattering relaxation time τGB, assuming that the grain size is uniform (about 50 nm) and the scattering probability is proportional to the grain boundary area. At the same time, the team found through experimental inversion that electrons enhance phonon scattering under high carrier concentration, so they added an exponential decay factor.

Unfortunately, their corrections did not seem to have any effect, and the final experimental results were still unsatisfactory, even worse than the original model. However, based on the experimental data they obtained, such corrections should have improved the experimental results.

This undoubtedly leads to a paradox.

What Chen Hui needs to do now is to unravel this paradox and find the overlooked parts of it.

But clearly, this is not an easy task.

As Chen Hui walked into the lab with his backpack, his mind was still racing with experimental data. He didn't realize what was happening until he saw a senior female student carrying a heavy box past him. He quickly went over to help her.

"No need, I can carry it!"

The senior sister said proudly, if she hadn't been carrying a box of things, she probably would have raised her hand to show off her muscles to Chen Hui.

"Just let her move it herself, she's good at it!"

Another senior student chimed in, "What did you buy this time?"

"banana!"

The senior sister placed the box in her seat and replied.

Are you going to set up a fruit stand?

"Have you finished the last box of oranges?"

"Don't worry, I bought green bananas this time. By the time they ripen, I'll have finished the whole box of oranges I bought before."

The senior student proudly opened the cardboard box, revealing bright green bananas inside. "If I can't complete the experiment and can't graduate, I'll sell fruit right at the school gate. Everyone, please come and support my business!"

"Okay, I'll promote you in the teachers' group and say you're my star student."

Just then, a voice rang out from the doorway.

Xiao Meng walked in from the doorway at some point.

"Oh, I can't accept that, thank you so much, teacher!"

The senior sister remained completely calm, even treating the trivial matter as an imperial edict.

Xiao Meng was both amused and exasperated. "Get your experiments done properly. If you want to sell fruit, get your degree first. Otherwise, I'll call the city management and report you!"

"Teacher, you're so cruel!" the senior student wailed.

Xiao Meng ignored him, called Yang Chi, and the two of them left the laboratory.

After Xiao Meng left, a low chuckle rippled through the lab, and everyone gave their senior a thumbs-up.

Chen Hui smiled wryly. That box of bananas must weigh about 20 kilograms. This senior sister is probably really planning to open a fruit stand.

"Junior brother, want some oranges?"

As soon as he sat down, his senior sister handed him an orange. Everyone in the lab was either a master's or a doctoral student, so Chen Hui, a freshman, could only be the junior here.

"Thank you."

Chen Hui did not refuse. Looking at the half-full box of oranges still on his senior's seat, he felt that he was doing a good deed.

"Have you heard? One of the junior students next door reached into a high-temperature crucible without wearing heat-resistant gloves during an experiment. He's so brave!"

"That's nothing. Your senior brother used to wash his hands in the bathroom and then unplugged the computer before they were even dry, and now he's cured of his internet addiction..."

"Wow, Tingting, this milk tea is so delicious! Where did you buy it?"

Not everyone was like Chen Hui, who started studying as soon as he arrived at the lab. While eating breakfast, everyone excitedly chatted about gossip.

"Hey, junior brother, I heard you've already published a Q1 SCI paper. What kind of research are you doing now? Is it difficult to publish papers in mathematics? Do you think your senior sister can study mathematics?"

The senior sister leaned over, blinked her big eyes, and asked curiously. Clearly, for someone who loves gossip, a new junior brother is definitely the biggest source of gossip.

"What I'm currently doing is establishing a standard model of 'topology-number theory'..."

Chen Hui answered, but suddenly frowned. Just now, a flash of inspiration seemed to have passed by, like a thunderclap that briefly illuminated the night.

He turned to look at the data on the computer screen, his mind racing.

However, he couldn't grasp this fleeting inspiration no matter what he did; it seemed to be just a hallucination.

"what exactly is it?"

What exactly did I overlook?

Chen Hui stared at the data in front of him. He had already processed the data into various graphs that were easy to analyze, but no matter how he processed them, he couldn't find the inherent connection between them.

Seeing this, the senior student didn't bother Chen Hui any further. She was also a researcher and understood how crucial this moment was.

The others in the lab also stopped gossiping and fell silent.

(End of this chapter)