Chapter 71 I made the right choice to return to China (added update 15 for leader flankerr)
Fortunately, Xu Yang still remembered his own job. He was shocked and did not continue to ask questions, but after reading Chang Haonan's optimization ideas were quickly put into the development of parallel computing programs.
Since the parametric modeling, sample point selection and establishment of the kriging surrogate model have been completed before, there is not much work left for Chang Haonan and Xu Yang to complete on site.
Despite this, it took the two of them almost ten hours to completely complete the development and inspection of the optimization program.
After all, in addition to optimizing the five independent variables of the three-section wing itself, Chang Haonan also added a flow deflector, making it extra difficult for himself.
"Huh——"
After checking the code for the last time to confirm that it was correct, Xu Yang pressed the Enter key, submitted the calculation task, then leaned back on the chair and exhaled a long breath.
The next step is to wait for the results to come out, and then decide whether it is necessary to conduct a separate optimization calculation for the design parameters of the flow deflector according to the situation.
"Is your canteen here... still open at night?" Chang Haonan asked hesitantly, looking at the moon that had risen into the sky outside the window.
From the intense work in the morning to now, he is really hungry.
"The cafeteria is closed, but I can treat you to Xiaozao." Xu Yang raised his wrist and glanced at the time, then replied.
“You still have a small cafeteria here?”
“Of course, at least half of us are night owls, and the small canteen is overcrowded in the middle of the night.”
Xu Yang said, spreading out his bun, and then arranging his hair slowly:
"It just so happens that I also have some questions about the differential evolution algorithm that I would like to ask you."
...
Some time later, Chang Haonan, Xu Yang and Yang Xia sat around a table in the canteen of the Institute of Computing Technology. The big fan next to them was blowing the wind. , barely bringing a bit of coolness on a hot summer night.
"I must admit that this morning, I still looked down upon you too much, thinking that you just expanded the application scope of the differential evolution algorithm."
Xu Yang, who left the office area, put on Wearing a mid-sleeve floral shirt, he was using chopsticks to stir the noodles in the bowl in front of him while asking Chang Haonan:
"But after reading the entire calculation program and instructions, I discovered that, You have actually fundamentally expanded the theoretical basis of the differential evolution algorithm. Can you tell me what you think? ”
Chang Haonan did not answer immediately, but glanced at Yang Xia next to him.
Since the Chinese Academy of Sciences asked Xu Yang to assist it with calculations, there must be no problem with the latter's confidentiality level.
But after all, there are many people in a place like the cafeteria, and he was not sure whether he could discuss the problem for a while.
Xu Yang, who was on the opposite side, naturally saw the reason for Chang Haonan's hesitation.
“Don’t worry, I understand the rules. I will only ask about things related to algorithm theory, not your specific project.”
At the same time, Yang Xia also nodded slightly, saying that if the discussion was only in the theoretical category, it would not be confidential, and the Institute of Computing Technology itself was also a confidential unit.
After confirming that there was no problem, Chang Haonan finally spoke:
“As one of the developers of the differential evolution algorithm, you should know that it mainly uses the differences between candidate solutions to generate A new individual, so it has huge advantages in global search speed and global search capabilities. My optimization process involves multiple independent variables. It should be normal to think of this method, right?"
After hearing this answer, Xu Yang raised his head and glanced at Chang Haonan with a strange look. After a while, he spoke again:
"Do you want to test my theoretical skills, or do you simply want to hear me praise you? Once again?" She didn't give Chang Haonan any time to intervene again, but continued directly:
“The differential evolution algorithm is originally designed to solve continuous optimization problems, and it is an unconstrained optimization algorithm, but what you are facing is a combinatorial optimization problem with constraints.”
< br>“So I have been thinking today, what should I do if I were to face this problem.”
“In the end, my answer is to use the definition of “subtraction” and “subtraction” based on the definition of continuous nature. "Add" to realize the calculation of the difference vector. However, although this idea is barely feasible, it lacks an operation method for the characteristics of the combinatorial optimization problem. Repair operations must be introduced to ensure the feasibility of the candidate solutions during the evolution process."
"But your idea is completely different. You optimize or design three new differential optimization algorithms from the perspective of the algorithm itself."
"Today I roughly understood the first one, which is based on position rather than the traditional addition and subtraction operation based on numerical values. In the crossover stage, a crossover operation based on arrangement is introduced to avoid destroying the good structural blocks formed and ensure understanding. Quick convergence. "
"As for the other two, I can only understand a rough idea. I even dare to say that even if you show your calculation program and design instructions to my teacher, he will not be able to do it in a short time. I fully understand within the time.”
“How are you satisfied with my compliment?”
Xu Yang put the chopsticks on the edge of the bowl and looked at Chang Haonan playfully:
"Besides, you just met me today. If someone else saw your code without a single comment, I would probably be furious."
"I..."
Conscience of heaven and earth, Chang Haonan definitely did not have the two meanings that the other party thought.
He simply didn’t know how far the intelligent algorithms had developed in 1996.
“It is really not convenient to explain this matter at the dinner table. Simply put, my optimization of the differential evolution algorithm is divided into three stages, corresponding to three different types of engineering application scenarios.”< br>
Chang Haonan smoothly mixed a clove of peeled garlic into the noodles, and then continued to explain:
"The first is the first one. You have already seen some of the key points, but not all of them. To speed up the evaluation of solutions and further improve the optimization performance, I also designed a fast combination heuristic method based on the idle time increment matrix. Local search strategy..."
"As for the second algorithm, in order to improve the diversity of the PDE population, avoid unnecessary repeated searches, and jump out of local extreme values, tabu search and permutation-based Combining the discrete differential evolution algorithm..."
"..."
Unlike when he taught fluid mechanics simulation at Beijing-Hang University, Chang Haonan himself did not originally understand the theory of this differential evolution algorithm. Understanding, but just learned through the system, and it is limited to the three types used in the wing optimization process, so although it is not a problem to apply, it is indeed difficult to explain it in a simple and in-depth way.
In the end, the two of them chatted until the staff in the canteen started cleaning and getting ready to get off work. Chang Haonan couldn't fully explain it clearly, so he had to say that he would do it next time.
"In short, it is difficult to explain these things clearly in a short time. If you are interested, after I return to the guest house, I can write you an explanation document about the optimization of the differential algorithm."
In fact, even if If there is no such thing, he is also going to go back and carefully sort out the relevant content of the differential evolution algorithm.
Although the system will only provide knowledge directly related to the project, Chang Haonan himself is not a complete novice. He can draw inferences from one example and deepen his understanding through his own learning ability.
On the opposite side, Xu Yang seemed to still be digesting what he just heard from Chang Haonan, so he just nodded blankly, and after a while he said with some emotion:
"No. Thinking about my years of studying abroad, my domestic colleagues have not only caught up with the world's top level in theory, but are also ahead of them in terms of technology application. They are far ahead!"
"It seems that I made the right choice to return to China after graduation..."
Looking at Xu Yang, whose thinking was gradually beginning to change, Chang Haonan thought for a moment, and finally decided...
Then Let her go.
╮(╯▽╰)╭
(End of this chapter)