Chapter 74 Mathematical Models The first class in the afternoon was Outline of Modern History, and Xu Qingzhou could not escape this class. At 1:50, Xu Qingzhou and four others arrived at the classroom. As soon as he entered, he felt everyone's eyes on him. Zhang Shuyi and Xue Ying sat together and waved, asking Xu Qingzhou and the others to sit in the back row. Later, they asked, "Xu Qingzhou, how did you apply to join the professor's project?" "It was by chance that I got to know Professor Gu. The Physics Department needed someone, so I went over there. Actually, I just did odd jobs." Xu Qingzhou said with a smile. "Even if it's just doing odd jobs, it's impressive. That's the professor's project." Zhang Shuyi sighed. Xue Ying kept her eyes on Xu Qingzhou and nodded in agreement: "Yes, I didn't expect you to be so good at math. If we have any questions in the future, we can come and ask you for help." "I just learned a little bit in advance." Xu Qingzhou smiled modestly. On the side, Xu Zhengyang caught Xue Ying's strange look towards Xu Qingzhou and sighed. Fortunately, he already has Dong Shan, otherwise, he might be jealous to death. At this time, the teacher wearing glasses walked in, and everyone stopped talking and waited for the class to start.
The class passed like this, and the teacher's speech was flat and even Xu Qingzhou almost fell asleep. After class, Xu Qingzhou carried his computer to the library to continue working on his paper, and went directly to the classroom to attend class meetings in the evening. School of Mathematics Library. Xu Qingzhou turned on his computer and found that he had received two emails. The first one is an email from the editorial department of Mathematical Inventions, indicating that the manuscript has been accepted. This part mainly involves the editor's preliminary evaluation of whether the manuscript meets the positioning of the journal to which it is submitted and the innovativeness of the manuscript. Pretty fast. The duration of this stage is uncertain and depends on how fast the editor can process the work. The second email, also from the editorial department, surprised Xu Qingzhou a little. The email showed that the manuscript had entered the "Awaiting Reviewer Assignment" stage. Generally speaking, after the paper has been initially reviewed by the editor, it will enter the external review stage. The manuscript will be handed over to 2 to 5 experts in the same field. This stage will be even longer, and the specific waiting time depends on the reviewers' schedule. Xu Qingzhou shook his head and closed his email. This matter could not be rushed, especially for a little Karami like him who had no reputation before. It was already fast that he could pass the preliminary review so quickly. The second paper is in the final stage. This article is almost entirely familiar content, so he planned to submit it directly to Physics Reports, an internationally renowned physics journal in physics and interdisciplinary sciences, after writing it. Time passed by minute by minute. Xu Qingzhou was writing very seriously. When he came to his senses, he found that it was already six o'clock and the class meeting would start in 15 minutes. He packed up his things and went to the classroom. The classroom, most of the students have arrived. Zhu Sitong was the first to speak on stage, reminding everyone that the school year had officially begun and that they should concentrate on their studies. Then he got to the point and said some encouraging words, encouraging everyone to sign up and contribute to the class. The two people participating in the class monitor election are Kong Xianbo and Zhang Shuyi. Of course, other students might have wanted to try it, but then they thought that Kong Xianbo and Zhang Shuyi were busy with class matters during this period, and if they just rushed in, it would be very embarrassing if there were only a few people in the dormitory, so they all gave up. Zhang Shuyi went up first and spoke eloquently and confidently. The content was almost the same as Kong Xianbo's first draft. She emphasized that she had been a class monitor and held various class committee positions before and could serve everyone well. After her speech, she left the stage amid strong applause. Then it was Kong Xianbo's turn. He went up to the stage, adjusted his glasses, and said, "Hello everyone, my name is Kong Xianbo. As you can see, I am standing here to run for class monitor." The two people's speaking styles suddenly became different. Even Zhu Sitong was a little surprised. He was originally optimistic about Zhang Shuyi. There was nothing wrong with her speech and it was passionate. But now, it seems that he thinks Kong Xianbo is also very good.
Even Zhu Sitong had this feeling, and of course other students did too. They felt sincerity in Kong Xianbo's words. When the voting was over, Kong Xianbo got 30 votes and Zhang Shuyi got 28 votes. The former became the class monitor and the latter became the league secretary. Xu Qingzhou didn't care much about it. After the class meeting, he bought a loaf of bread on the way and continued to hang out in the library. The next day. There was no class on Tuesday morning, so Xu Qingzhou got up early, went to the cafeteria to have breakfast, and arrived at the laboratory on time. Wang Wei and Gong Yunfei are standing in front of the instrument, testing samples and collecting data on the samples' lattice structure, element distribution, magnetic field state, and so on. "Junior brother." Wang Wei looked much more energetic than yesterday and asked with a smile, "Professor Zhao told you about our project yesterday, right?" "Yeah, I have a general understanding of it." Xu Qingzhou nodded. Wang Wei pointed at the computer screen and said, "All the experimental data has been uploaded to the computer. There is also a data page on your desk. Take a look at this set of data first. Do you find anything unusual?" "Something is wrong. This peak value seems too high." Xu Qingzhou saw the problem at a glance. At a temperature of 70°C, the resistance value suddenly increased to . Wang Wei sighed, "Yes, this is the troublesome thing. In addition to the huge amount of experimental data, we also have to clean the data and use the IQR method to remove noise and outliers. On this basis, we can build the model." "These jobs are complicated, and I'm not very good at math." "So, we need a professional who is proficient in mathematics to help us solve this problem." Xu Qingzhou walked to his desk, flipped through the data paper, thought for a moment, and said seriously: "I can give it a try, it shouldn't be a big problem." "I still have to go to the materials laboratory to supervise the production of samples. I'll leave this to you. However, we are in a hurry, so I will check the progress with you every three days." Wang Wei gave him some time. He did not doubt Xu Qingzhou's talent in mathematics. He must have the ability to be taken over by Professor Zhao. But he was only a freshman after all and might not have even followed the experiment. There are differences between pure mathematics and applied mathematics. "I'll try to be as fast as possible." Xu Qingzhou understood what Wang Wei meant. Wang Wei nodded, and left in a hurry without staying any longer: "Okay, I'll leave this place to you." Xu Qingzhou sat down in front of the computer, looking at the data spread out on the table, thinking about where to start. The data is indeed very complex and can give people a headache. I don't know how to start with a big model. Maybe... Xu Qingzhou's eyes darkened. I can do it step by step, peeling off the cocoon and pulling out the silk, just like building a building, accumulating bricks one by one. First, the electromagnetic characteristic analysis model and the heat conduction analysis model are established separately, and finally the models are coupled by simultaneously updating the solutions of the electromagnetic field and heat conduction equations during the solution process. Maxwell equations (differential form): \begin{align*}\nabla \cdot \mathbf{E}&=\frac{\rho}{\varepsilon_0} Superconducting state equation: J \leq J_c(T， B)J≤Jc(T，B) Fourier's law of heat conduction (three dimensions): \frac{\partial T}{\partial t}=\alpha \left Xu Qingzhou took out a piece of draft paper, wrote down a few equations on it, and slowly exhaled. This is a good start. (End of this chapter)