Chapter 1167: Producing airplanes like producing sausages?
"Cough-cough-"
Just when Yang Liang was ready to perform a "crazy apology in the face of doubts" on the spot, a cough suddenly came from the laptop that was almost ignored by everyone.
The meeting room, which had been bustling with activity, suddenly became quiet.
However, the warm atmosphere was not interrupted.
As for Yang Liang, who was on the stage, when he heard that Chang Haonan seemed to be preparing to ask a question, his limbs became weak and his hands and feet became cold, as if he was about to faint...
The successive attacks from the four players in front of him were already enough to exhaust him.
If this big guy delivers another fatal blow...
At a certain moment, two big words seemed to flash before his eyes.
Delayed completion.
Although Professor Li Xiongjiang felt a little sorry for his own student on the stage, as things had come to this point, he could not forcibly interrupt the other judges to ask questions.
So I had to force a smile:
"Academician Chang, please ask."
However, Chang Haonan in the picture just tapped the paper on the table with the pen cap, and then said something that no one expected:
"Um...I didn't actually mean to ask a question."
As he spoke, he pulled in two more sheets of paper filled with formulas from outside the screen:
"I just wanted to say that I happen to have some existing research results that seem to be able to solve the problems raised by the other reviewers just now..."
"???"
The sudden change in the situation at this moment threw everyone into a state of panic.
Several professors at the scene were stunned at first, and then their faces showed joy——
The reason why they asked so many questions in a row was not because they really didn't want Yang Liang to graduate.
But I am really interested in the topics that the latter is researching.
But as he was asking questions, he ended up hanging on the stage...
Now that someone has suggested that the problem can be solved, I am naturally curious and excited.
However, members of the same research group and some graduate students who came to attend the class simply had never seen such a scene before and were ready to watch the show.
As for Yang Liang, who was about to cry just now...
When these words reached his ears, they sounded like heavenly music.
When I was defending my thesis, the academician not only did not ask any questions, he even took the initiative to answer them for me.
I can brag about this for half my life...
In short, although the conference room remained as quiet as before, the atmosphere had changed 180 degrees...
……
In fact, for Chang Haonan on the other side of the computer, the calibration and compensation of ERS points was not a very complicated problem.
It just requires some theoretical knowledge.
But because of this, it seems difficult to explain this problem in just a few words...
After organizing his words for a while, he spoke:
“As Yang Liang said at the beginning, ERS points are usually deployed on assembly auxiliary jigs to establish assembly coordinate systems. In this case, their displacement and deformation relative to OBP and TBP are linear. Therefore, an optimization model of the minimum weighted distance error function between multiple sets of compensated ERS theoretical values and actual measured values can be constructed…”
"For example, for g sets of data measured at m stations and k temperatures, the matching relationship between the measured values and the corrected theoretical values is Σ(i=1,n)(│RnP^k+Tn-Pa^k│)..."
Thanks to the advancement of network technology, Chang Haonan can write this difficult-to-read formula directly on a piece of paper, and then put it close to the screen to show it to people on the other side of the network cable.
At first, Yang Liang quickly returned to his seat and took out a notebook, ready to write down some useful things.
But before writing a few steps, he scratched his head lightly, then silently put down the pen, looked forward with eyes full of wisdom, and sometimes nodded slightly, and sometimes frowned as if thinking...
Anyone who really knows the business can tell at a glance that this kind of behavior is just pretending to understand.
Fortunately, the others were either not paying attention to what was ahead or were in the same situation as him, so nothing happened.
After a short pause of a few seconds, Chang Haonan put down the paper in his hand and continued to introduce himself:
"This is a typical unconstrained multi-objective nonlinear optimization problem... I don't know if you have read the paper that Professor Abela Liesel and I published last month. In it, we proposed an improved Levenberg-Marquardt algorithm that can be used to solve this problem with just a few adjustments."
"The only pity is that this achievement is too new, so there is no ready-made preset software available. If you have the ability to design programs and algorithms, you can design your own program to perform the calculations. If not... MathWorks has contacted Professor Lissel a few days ago, and MATLAB should soon provide a calculation toolkit..."
"..."
Listening to Chang Haonan's explanation, Professor Li Xiongjiang sighed with a hint of regret -
This is what we call research...
As soon as I submitted an article, before I could see any results, a large application company came to me.
But then again, others already have a large application-side company.
Can't compare...
While he was being emo, the people who had asked questions enthusiastically just now were also motivated again.
Although no one has actually read it yet, and may not even know that Chang Haonan has published a new paper, it is obviously impossible for anyone to question the truthfulness of what he just said.
At least it was impossible to question it on the spot.
And if the accuracy problem of large-size three-coordinate measurement can be overcome.
Then many problems seem to be solved...
"Academician Chang."
The professor who asked the question first took the lead again:
"Yang Liang's research is based on the assembly of a single machine. If we expand our perspective and apply the same technology to the entire production line or even the workshop, combined with indoor GPS positioning, is it possible to get rid of the restrictions of the assembly process on special jigs?"
The traditional aircraft assembly process adopts a non-automated mode, and each operation is highly dependent on manual labor. Therefore, for aircraft of different models and design features, a series of assembly jigs need to be specially designed for the production process.
For example, the jig used to install the engine for the C808 aircraft cannot be used for the C909 aircraft.
Even if the same model undergoes some design changes, the auxiliary tooling must be replaced accordingly.
This undoubtedly greatly reduces production speed and flexibility.
Chang Haonan also gave a positive response:
"Given the actual accuracy of the current three-dimensional coordinate measuring equipment, it is still difficult to completely get rid of the jig... But most of the special tooling can be replaced with general equipment. On the one hand, it can greatly reduce costs, and on the other hand, it can also improve production flexibility and even allow different models to be produced on the same line..."
At this point, he suddenly thought of a classic metaphor from more than half a century ago:
"It's like making airplanes like sausages!"
This immediately caused a burst of laughter.
Next, several defense judges including Chang Haonan started an intensive discussion and communication, and for a moment they forgot about the real person on the podium.
Although Yang Liang felt a little embarrassed, his degree was the most important thing at the moment, so he was happy to see this scene.
However, it is a thesis defense after all.
It is impossible to always treat the respondent as an invisible person.
Finally, it was Chang Haonan who first caused the discussion to go off topic and got back to the point:
"Student Yang Liang."
Yang Liang, who was almost in a trance, was almost frightened by this sound and jumped up. He quickly stood up straight with his chest and stomach straightened:
"Academician Chang, please criticize and correct me!"
This somewhat startled reaction made Chang Haonan couldn't help laughing.
"Don't be nervous. Overall, your defense was very good. It's just that some of the questions were obviously beyond the scope of this doctoral thesis, but this cannot be considered as your shortcomings..."
After hearing this comment that somewhat set the tone, Yang Liang's anxious heart finally calmed down.
Professor Li Xiongjiang seized the opportunity and used a sudden hammer-dropping trick:
"So...dear judges, do you have any other questions?"
Chang Haonan had already said so much, so naturally, it was impossible for others to cause any more trouble. They all shook their heads or waved their hands, indicating that it was enough.
Zhou Shuwan, who had hardly spoken a word during the entire process, now revealed a relieved smile. His tense upper body slowly relaxed and he leaned back on the backrest.
It was only then that he realized the back of his shirt was almost soaked.
After all, it has only been two years since I graduated with my PhD, so it is easy to recall my memory of the defense I made that year...
"Academician Chang is still awesome..."
Looking at the conference room in front of me that had returned to a happy state, I couldn't help but sigh in my heart:
"Thanks for inviting me here..."
