Chapter 76 Encountering Problems Xu Qingzhou returned to the dormitory carrying his schoolbag, and there was a pile of club flyers on the desks of Xu Zhengyang and his classmates. "It's so lively." Xu Qingzhou smacked his lips. Xu Zhengyang was still browsing the club information on the flyer. When he saw Xu Qingzhou coming back, he asked, "Old Xu, you really don't want to join the club?" Xu Qingzhou put down his schoolbag and shook his head: "No, even if I join, I don't have time to go." "I signed up for the Street Dance Club and the Guitar Club." Xu Zhengyang smiled and recommended to Xu Qingzhou, "Old Xu, why don't you join the Street Dance Club? Those girls are so cool, each one is more exciting than the other." "Didn't you say you were tone-deaf?" Xu Qingzhou paid more attention to the guitar club this guy joined. Usually, when they were taking a bath, they howled like a ghost, and few of them could keep tune. Xu Zhengyang rolled his eyes and retorted, "Just because you are tone-deaf, can't you have a heart that pursues your dreams?" "This guy was actually tricked by the pretty director of the guitar club." Kong Xianbo ruthlessly revealed, sighing, "And Old Zhai also signed up for the guitar club." Zhai Ziqiang said somewhat embarrassedly: "I just want to learn a musical instrument myself." Xu Qingzhou didn't tease Zhai Ziqiang about wanting to learn a musical instrument. It was not easy for Zhai Ziqiang's family to support a Peking University student, so learning a musical instrument was not realistic. He smiled and looked at Xu Zhengyang: "Old Xu, look at this beautiful girl. Will Dong Shan be jealous if she knows?"
"Dong Shan is also in the street dance club." Xu Zhengyang shrugged. Xu Qingzhou was a little surprised. He didn't expect that Dong Shan would be interested in street dance. He was also a little worried about Xu Zhengyang. At least now it seemed that a girl like Dong Shan had a passionate heart. Although Xu Zhengyang looked playful, he was just a talker and a rookie. He didn't know if he could hold on. In the dormitory, everyone continued chatting for a while. Except for Xu Qingzhou who didn't plan to sign up for anything, Kong Xianbo planned to sign up for the Student Union, and Zhai Ziqiang signed up for the Literature Club in addition to the Guitar Club. At 12 o'clock in the evening, Xu Qingzhou took a shower and went to the study room on the 3rd floor of the dormitory building with his computer. Looking at Xu Qingzhou walking out, Kong Xianbo, who was originally lying on the bed, frowned slightly, silently stood up, got out of bed, and took out the Mathematics 1 textbook. "Lao Kong, what are you doing with a book so late at night?" Xu Zhengyang was lying on the bed, grinning foolishly at his phone. "Study." Kong Xianbo answered in a muffled voice. Hearing these two words, Zhai Ziqiang, who had already closed his eyes, suddenly woke up from sleepiness. He opened his mobile phone and looked at the blackboard notes he had taken in class today. For three whole days, Xu Qingzhou was basically immersed in various complex data, as if he had regained the state when he was conducting the experiment, and maintained a life between the library, dormitory and cafeteria. However, even so, by the evening of the next day, he had only completed the establishment of the second set of models. While considering the influence of magnetic field strength on the critical current density, he added the variable of temperature and optimized the model to include the influence of temperature on the critical magnetic field strength. The relationship between the critical magnetic field strength $B_c$ and the temperature $T$ is: B_c(T)= B_0 \cdot (1 - T^2/T_c^2)Bc(T)=B0(1T2/Tc2). Xu Qingzhou turned on the computer, entered Python, and substituted the temperature-dependent critical magnetic field strength into the critical current density model. Bc = B0 *(1 -(T/Tc)**2)#Calculate the critical magnetic field strength if Bc raise ValueError("Temperature is too high for superconductivity.") Jc = J0 *(1 - B / Bc)**n return Jc After Xu Qingzhou entered the numerical values, he suddenly found that several sets of data were abnormal. (B, T, J0=1e10, B0=12, Tc=4, n=1) The output value, n should be 2. n is the rate at which current density decreases with magnetic field strength, which means that there was a problem with sample No. 22 during the 10th test. In the study room, in addition to Xu Qingzhou, there was another boy who was working hard. He looked at the various data in front of Xu Qingzhou, as well as the thick draft paper with dense calculations written on it. The boy couldn't help but sigh, wondering where did this great man come from. He met this man in the study room for two consecutive days, and he seemed to be doing an extremely difficult calculation. The boy took a deep breath, cheered himself up, and suddenly felt the desire to win.
Even if you can’t compete with me in studies, you can’t lose by staying up late to attend classes! On this side, Xu Qingzhou didn't notice the boy's strange look at all. He had already started to screen the data in detail. First, he checked the model. If there was no problem with the model, he would check the data, time, and magnetic field strength. There are also some problems when the data after sample No. 22 is brought in. Yes, if the current experiment continues, by the time we get to sample No. 80, all data seem to be improving steadily. But once we move on to sample No. 100, the value of n will become 0. Niobium-titanium alloy is a material with zero resistance. However, no matter how delicately and perfectly it is processed, from a physical point of view, there will be losses in the transmission of electric current. When n is 0, thinking in reverse, the current loss from the positive pole to the negative pole is 0. Another hour passed, Xu Qingzhou let out a long sigh and leaned back in his chair. He seemed to have reached a bottleneck. I can't find any problem with the data, so it's just the materials? Rubbing his temple, Xu Qingzhou glanced at the time and found that it was already 3 . The senior who stayed up late with him left at some point. He simply turned off the computer, took his things, and went back to the dormitory to sleep. On Thursday morning, after the senior class ended, Xu Qingzhou went straight to the laboratory. "Junior brother, is there any progress?" Wang Wei asked as soon as they met. After not seeing him for three days, Senior Brother Wang seemed much more haggard. Wang Wei was indeed very worried. Not only him, but also Zhao Shengwen and Hong Yayu were worried. Time waits for no one. According to rumors, Jinling University has already built the model and has started testing. "Not sure yet." Xu Qingzhou sat down directly in front of the office and said, "Brother Wang, I want to take a look at the internal organizational structure of each sample first." "Okay." Although Wang Wei was anxious, he still nodded slightly. He had already waited for three days, so he didn't mind just a little longer. The information in the computer is very complete. 样品类型包括Nb-44Ti、、Nb-48Ti、Nb-50Ti、Nb-53Ti、Nb-55Ti In addition to the structural diagram, there is also a corresponding table of sample preparation ingredients. In addition to the two main raw materials of niobium (Nb) and titanium (Ti), a small amount of trace elements such as hafnium (Hf) and zirconium (Zr) are also added. Xu Qingzhou continued to observe the structural diagrams of niobium-titanium alloy materials, and at the same time called up the sample preparation composition table to confirm his guess. As it approached 11 o'clock, Xu Qingzhou looked across at Wang Wei who was sorting out the data and said, "I found the problem." (End of this chapter)