Before entering Cai Xingquan's scientific research team, Du Xiaodi only had a junior high school diploma, which was only more solid than the foundation of Feng Xiaochen's junior high school students.For more than a year, she worked as a welding experimenter in Cai Xingquan's team, and on the other hand, under the guidance of several graduate students assigned by Cai Xingquan and Feng Xiaochen, she tutored high school and university courses, and finally obtained Cai Xingquan's graduate students with excellent results.

The topic that Cai Xingquan gave to Du Xiaodi this time is quite difficult.Du Xiaodi's self-blame is actually demanding of himself.The calculation of welding heat process is extremely complex, although as early as the 1940s, there has been Feng Xiaochen said Rosenthal-Rykalin analytic formula, but considering the complex boundary conditions, heat source distribution, nonlinear and other issues, the use of this formula to solve the practical problem, for the mathematical skills of scholars is still a serious challenge.

Because the formula is extremely difficult to derive, most of the problems solved in practice are using numerical simulation methods, that is, using various values to repeatedly try and collide with the final result.For example, if you haven't learned the root-opening method, then the square root of 2 can only be tried.

You can first assume that the square root is 1.4, but the square of 1.4 is 1.96, which is smaller than 2, so it needs to be increased.Then assume that the square root is 1.5, and its square is 2.25, which is larger than 2.In this way, you can take the comfic point of 1.4 and 1.5 1.45, calculate the square is still 2 times larger, then folded, take 1.425......, so try again and again, and finally find 1.414 such a relatively close to the real result.

The principle of numerical simulation is roughly so.But to do numerical simulation, it is necessary to count some simple calculations many times over and over again, and the workload is very frightening.Numerical simulation is widely used, or after the invention of the computer, because the computer is tireless, it can follow a program repeatedly to try to do things that these human beings can not do.

Formula derivation and numerical simulation are two ways to solve equations.Du Xiaodi did not understand these things in the past, but he spent more than a year in Cai Xingquan's scientific research team, and this knowledge was at least mastered.Regarding the 16MnR steel cryogenic welding process she was studying, the equation involved was very complex, and she thought from the beginning that numerical simulation should be done.But numerical simulation requires a computer, and this obstacle is difficult for her.

In this era, microcomputers have been widely used, and there is an IBM286 computer in Cai Xingquan's laboratory.But to do complex numerical simulation, this computer is not enough, you have to use a minicomputer or a medium-sized machine.The computing center of the University of Technology has an IBM370, which can do these calculations, but the problem is that the teachers and graduate students who need to use this computer are too many, and the computing center has to give the various departments the distribution machine, only when it is your turn, you can use it.In order to make maximum use of this computer, the computer time of the computing center is arranged 24 hours a day, but even the 12 o'clock in the middle of the night is in short supply.

Du Xiaodi belongs to the research group of Cai Xingquan, Cai Xingquan belongs to the material department teacher, the calculation center to the material department of the machine, but also between the teachers between the second distribution, fell to Cai Xingquan's name is very limited.Du Xiaodi knew this situation, naturally and it is not convenient to compete with teachers or brothers and sisters for these precious opportunities.Since the way of numerical simulation cannot go, she thinks that she will return to the way to solve the equation, and she wants to find the analytic solution of this set of formulas by her own efforts.But who would have thought that solving such an equation is not something that ordinary people can do at all, and that it is a mathematical bullman such as Gauss or Kolmogorov, perhaps there is still a little hope, and Du Xiaodi is just a junior high school background welder.

“Wang Chen, am I too stupid?”Du Xiaodi took Feng Xiaochen's arm and asked aggrieved.She has been tossing these equations for several days, it can be described as exhausted, it is difficult to have an opportunity to talk, she almost will cry out.

Feng Xiaochen patted her arm and comforted: "Xiao Di, it's not you stupid, but you underestimate the difficulty of this matter."This equation is impossible to solve, and this has long been conclusive.You see, these foreign literature, are also using numerical simulation solutions, these people are big-name professors, deep academic skills, and there are doctoral, master's team, even they can not solve the equation, how can you solve it?" 」

“Is it?”Du Xiaodi asked, she pondered it in detail, and it seemed that Feng Xiaochen's explanation was really reasonable.However, she did not relax, she frowned and said: "However, if I do not solve this equation, I can't prove that we designed the process is better than the process used to be used as a comparison, although the micrograph can see the difference, but there is no theoretical proof that it is not enough."

“You can do numerical simulations, why hang yourself from a tree?”Feng Xiaochen asked.

"Didn't I just say that we didn't have time?"Du Xiaodi said.

Feng Xiaochen smiled and licked her hair and said, "It's difficult to find a husband, haven't I told you many times?"Beijing has several large factories that equip us with systems, all of which have large or medium-sized aircraft imported from the United States.Their usual computing tasks are not heavy, and I contacted them and borrowed their machines without any problems.In any case, your subject is also entrusted by the re-installation office, which is not a fake public and private."

“Really?”Du Xiaodi's eyes suddenly brightened, "Whising, is this really not against the principle?"

Feng Xiaochen shook his head firmly and said, “Absolutely do not violate the principle.”In addition to your task, if you Professor Tsai have anything to do to calculate, you can also take it over, which is called the full use of resources.”

“Very good!”Du Xiaodi smiled and said, “Since this is the case, then I will not be busy.”I'll go to the garrison and buy meat for you."

“Forget about it.”Feng Xiaochen grabbed Du Xiaodi, who was about to change clothes and go out, said: "You are tired of this, your eyes are all panda's eyes, or hurry to sleep."It's okay to cook, and your job now is to sleep."

“Well, that’s okay.”At this time, Du Xiaodi felt the fatigue from the inside out, just as the people who had walked dozens of miles suddenly stopped, and they were all tired of indescribable.

"I've been cleaning up my bed... I've been sleeping on the table for two days."Du Xiaodi said embarrassedly, ready to clean up the bed information.

Feng Xiaochen pulled her from behind, could not say that a princess hugged her, picked her up, and said, "If you pack something else, you go to my room to sleep, these materials wait until you sleep up and then organize."Come on, I'll hold you."

“No, no!”Du Xiaodi protested on his mouth, but at the same time put his hand around Feng Xiaochen's neck and made himself safer in Feng's arms.

When Feng Xiaochen took Du Xiaodi out of her room, came to her room, and put her on her bed, only to find that Du Xiaodi had fallen asleep.Perhaps, she felt that Feng Xiaochen's arms were both safe and warm, and she could make her forget all her worries at once.

Du Xiaodi's sleep from morning until evening, when she opened her eyes, smelled a seductive aroma in her nose, which was the smell of stew chicken.

Du Xiaodi came to the courtyard in his clothes, and saw Feng Xiaochen sitting in the corner of the yard, and there was a small round table in front of him, and he was lying on the round table with something written.Hearing the movement of Du Xiaodi going out, Feng Xiaochen raised his head and smiled and asked:

“Wake up?Do you feel better?”

“All right!”Du Xiaodi said with some embarrassment that she could not even remember when she fell asleep, only that she felt that this sleep was so smooth, and the tiredness accumulated for a few days had been swept away.

“You wash up and get ready to eat.”Feng Xiaochen said, "I went to the kitchen in the morning to buy a chicken, and I have been stew for a few hours, so I will make up for it."

Du Xiaodi smiled, “I dare not make up for it casually, in Beijing for more than a year, I have gained several pounds.”If you get fat like this, you won't be able to drill the tube in."

Ordinary people do not use the drill pipe as the goal of maintaining his body, but Du Xiaodi is a welder, and he is a welder engaged in pressure vessels, and the drill pipe is her most common job.Many times, the female welder is stronger than the male welder, that is, their body is more delicate, can drill into a small space to carry out welding operations, and the large waist round male welders in this time can only be sighed.

Hearing Du Xiaodi say about the drill pipe, Feng Xiaochen smiled and asked, “You have all read graduate school, will you drill the tube later?”

Du Xiaodi replied very seriously: "Of course, I want to drill, I am a graduate student of electric welding, how can I lose my own business?"

"However, your current line is a welding hot equation, Professor Cai is afraid that he will not burn electric welding?"Feng Xiaochen.

Du Xiaodi said: "Professor Cai will burn electric welding, but usually do not do much, not very skilled."I said to Professor Cai, whether I am a graduate student or not, I will continue to work with this welding experimenter, in fact, I prefer to burn welding."

"Well, then, go ahead and drill the tube, but I'm sure you won't get into it one day."

“Why?”

“Because sooner or later...” Feng said, deliberately stopping, while handing over a spherical shape on his stomach.

Du Xiaodi did not understand for a while, after a while, from the expression on Feng Xiaochen's face to understand what he pointed, can not help but look ashamed of red.She rushed forward, and her fist was a violent attack, and she scolded while playing:

“You have to die!That’s all you say!”