Chapter 1166: Reply, only answer but no defense

Just as Zheng Guogang was debating with a group of scholars.

The other side of the world.

Inside the conference hall of the No. 1 Teaching Building at the Yuquan Campus of Zhejiang University, there was a busy scene just like that before the war.

Zhou Shuwan, dressed in a suit and tie, sat at the head of the long conference table, looking with a little emotion at the dozen or so colleagues and students in front of him who were gathered around one person, confirming various details about the thesis and PPT.

Just like returning to the scene where he defended his doctoral dissertation two years ago.

In fact, during his master's degree, Zhou Shuwan and his supervisor had participated in the imitation and improvement of the HTY8 ejection seat and the research and development of the HTY5 ejection seat.

After successfully transferring to a doctorate in 2000, he was lucky enough to take advantage of the rapid development of China's aviation industry.

In just three years, the two main fighter jets, the J-11B and J-10A, completed high-intensity test flights with a total duration comparable to the past decade combined, and were successfully finalized and put into service.

This process also provides a large amount of real data for the research on ejection seats and pilot human-machine performance.

Ultimately, both seat models were finalized before the end of 2002, one step ahead of the aircraft.

As a result, Zhou Shuwan was able to obtain his doctorate degree in just two years and entered the 610th Institute of China Aviation Industry Group, which is the Aviation Lifesaving Research Institute.

In actual work, he spends most of his time at the Gaofei Group, responsible for seat adaptation for the new generation of medium bombers that are under development.

As for why he appeared in Zhejiang University...it was largely a coincidence.

Shortly after Zhou Shuwan officially started working, in response to the country's call to "cultivate world-class high-level engineers", Zhejiang University first piloted the introduction of an excellent engineer training program in graduate training.

That is, graduate supervisors and front-line engineers from enterprises will serve as mentors together to train talents who can solve practical production problems immediately after graduation.

At that time, Zhejiang University was cooperating with Gaofei Group to carry out research and development of digital measurement and track movement technology.

In short, Zhou Shuwan joined Professor Li Xiongjiang's research group as an engineer.

And today happens to be the graduation day of the first student he taught.

Zhou Shuwan lived up to expectations and made full use of his connections, directly inviting Chang Hao to participate in the defense.

For the entire research team, this is certainly something that deserves praise.

Professor Li Xiongjiang posted the defense poster in the most conspicuous place outside the teaching building half a month in advance.

But for a graduate student who is just about to graduate, the appearance of such a big shot on the defense committee is not really good news.

After all, under normal circumstances, considering the tutor's own face, as long as the thesis itself has passed the review, the subsequent defense process is almost just a formality.

Even if you only answer questions without defending them, it is not difficult to obtain your degree.

However, in recent years, the few cases where students failed to graduate due to thesis defense were almost all because they aroused doubts from the bigwigs...

Of course, on the other hand, if you can perform well in the defense, you may also be favored by the big guys, and thus upgrade your diploma from a stepping stone to a battering ram...

Therefore, it is not surprising that such a tense and anxious scene would occur...

"Don't all gather around Yang Liang."

Finally, Zhou Shuwan, who couldn't bear to watch any longer, tapped the table lightly, attracting everyone else's attention, and then said:

"People have trouble breathing when they are nervous, and you all gathered around him, which will only make his mind more confused."

Perhaps to improve his persuasiveness, he added one more sentence at the end:

"This is what Academician Chang told me before."

Sure enough, this sentence is both persuasive and attractive.

Not only the others, but even Yang Liang himself, who was about to defend his thesis, looked up with some curiosity, his eyes flashing with a blazing fire of gossip.

"Teacher Zhou, I heard that you and Academician Chang... were classmates?"

A younger girl next to her suddenly asked.

In fact, ever since Zhou Shuwan joined the research team, everyone has been curious about these things.

I just haven't had the opportunity.

"I……"

Faced with this irrelevant question, Zhou Shuwan's face froze.

However, in the end, he nodded freely:

"Indeed, we were undergraduate classmates."

After he finished speaking, without waiting for others to continue speaking, he continued:

"In fact, he was already a professor when I hadn't even finished my master's degree... and he was also present when I defended my master's degree, so to be honest, if I were you, I wouldn't be nervous at all..."

In fact, this is forcibly changing the subject.

Chang Haonan was indeed present when Zhou Shuwan defended his master's thesis.

But the problem is that the two people were not participating in the same defense.

Although Yang Liang on the other side couldn't possibly know these details, he couldn't help but roll his eyes and complained in his heart:

Nonsense, you and he are classmates, so there is no need to be nervous, but he and I are not...

For a moment, the entire conference room fell into an awkward silence.

Fortunately, after this interruption, the atmosphere, which had been so tense that it was about to break, finally relaxed a lot.

Especially Yang Liang's mental state, it seems to have improved a lot...

……

Soon, as other reviewers including Li Xiongjiang arrived one after another, it was finally time for the defense to begin.

A laptop is placed on the desk to share the situation in this meeting room in real time.

Chang Haonan was currently in Gaojing following up on the research and development of a high bypass ratio turbofan engine, so he could only attend the meeting via video.

Fortunately, by the end of 2004, the Internet speed for individual users had basically entered the era of being measured in Mbps.

The bandwidth limit for commercial users has also reached double digits thanks to technologies such as VDSL.

It can already support some video conferencing that do not require high image quality.

A few seconds later, Chang Haonan's face appeared on the laptop screen.

It looks like it is also in a conference room.

"Academician Chang, we are ready here. Do you think we should start right away?"

Professor Li Xiongjiang asked politely.

Chang Haonan initially agreed to attend largely out of respect for Zhou Shuwan.

But after reading Yang Liang's graduation thesis in detail, I did become interested in it.

So he nodded and pointed his hand out of the screen:

"Please Yang Liang start your defense!"

When Chang Haonan called his name directly, Yang Liang, who was already standing behind the podium, froze in his entire posture even though he had prepared himself mentally.

Then he took a deep breath and gently turned the microphone back in front of him:

“Dear teachers and students, I am the respondent Yang Liang. The title of my doctoral thesis is “Application of Digital Measurement and Spatial Attitude Positioning Technology in Aircraft Automatic Assembly Process”. It was completed under the joint guidance of Professor Li Xiongjiang and Engineer Zhou Shuwan…”

"First of all, the background of the topic selection of the paper. As a strategic industry that promotes the rapid growth of the national economy, the aircraft manufacturing industry directly affects the country's international competitiveness and military deterrence. Aircraft assembly is an important stage in the entire production process, involving a large number of complex components and auxiliary process equipment. The coordination of each link is complex..."

Although it was impossible not to be nervous in the face of such a situation, after all, he had done real research for four years. Therefore, after he really started to introduce the content of the defense, Yang Liang gradually got into the state:

"Our school has cooperated with the Aviation Industry Corporation of China Gaojing Aircraft Company to develop the first automated spatial positioning and assembly production line in China. However, during the aircraft assembly process, measurements are often not possible due to obstructions..."

"My research is based on the synergy between multiple laser trackers. I use public observation points to transfer laser trackers so that aircraft assembly can be carried out in a unified assembly coordinate system..."

"..."

To be honest, even Chang Haonan did not expect that after he and Yao Mengna gave it an initial velocity, the Aviation Industry Group next door would be able to advance the automated assembly technology so quickly.

At the turn of the century, on the eve of the split of the head office, the Gaofei Group's method of producing the JH-7A was still traditional manual assembly, but mathematical optimization methods replaced the past purely empirical methods in the management processes of parts production, working hours and work station allocation.

In just four years, we have begun to consider introducing automation technology in the spatial positioning and assembly process of large components.

If it can be combined with the large component pre-connection process that he had previously tested on the Falcon 8Z early warning aircraft, the working hours taken for an aircraft in the final assembly process will likely be reduced to one-fifth or even one-tenth of the current level, while the assembly accuracy can actually be improved.

Of course, the current research is only the beginning...

Doctoral dissertations are generally long, and Yang Liang received guidance in both theory and engineering, so the amount of content involved was quite exaggerated.

After 40 minutes, the PPT finally turned to the last page.

"My defense is over, thank you everyone..."

Looking at the words "Please feel free to criticize and correct" on the computer screen in front of him, Yang Liang finally breathed a sigh of relief and stretched out one hand to support the podium to resist the slight dizziness.

However, I didn't dare to take it too lightly.

Finishing the PPT presentation is just the first step of the defense.

The real storm is still waiting behind...

……

After entering the question-and-answer session, the four defense judges on the scene looked at Chang Haonan on the screen almost at the same time.

Although the latter is not the chairman of the review committee, from various perspectives, he should definitely be the first to speak.

Facing this scene, Yang Liang also held his breath again...

However, Chang Haonan just waved his hand calmly:

"You guys should go first, I'll ask questions later..."

He didn't even raise his head, but was writing and drawing something on the edge of the paper in front of him.

Firstly, with his current status and position, as long as he opens his mouth, he will basically set the tone for the entire defense, and the people who follow him will most likely not have any different opinions.

Secondly, Yang Liang’s report had indeed given him a lot of inspiration…

Seeing that Chang Haonan was not going to express his opinion, the other professor quickly sat up straight:

"Your paper mentioned that for multiple laser trackers to conduct collaborative measurements, it is necessary to frequently transform the tracker coordinates, and you also gave a mathematical model for station transfer errors. However, this model is calculated based on common observation points. How do you plan to solve the distribution and error problems of the observation points themselves?"

Yang Liang forced himself to calm down and thought for a few seconds.

Fortunately, this is a tricky angle, but the difficulty is not a big problem.

"Public observation points are divided into three categories, namely optical tool sphere points (OTPs), benchmark tool sphere points (TBPs) and enhanced system reference points (ERS). OTPs and TBPs are arranged on tooling and stable ground respectively, and can be used as reference benchmarks for target sphere calibration..."

However, the questions did not end there...

"When the temperature changes at the aircraft assembly site, the thermal expansion characteristics of the tooling and jigs in their main dimensions are different due to the different materials, shapes and structures. Even for the same component, the expansion characteristics in different directions in space may be different. Your transfer method only involves one expansion degree of freedom. Is it not reasonable?"

Yang Liang: "This is limited by the current error modeling theory. Too high a degree of freedom will lead to divergence or false convergence of the calculation results. According to simulation tests, the current accuracy can already meet the requirements of existing models. Of course, our next research will focus on overcoming the problem you raised..."

"You just mentioned ERS points, but in formula 97-6 on page 41 of your paper, only the scaling relative to the center is introduced, that is, only the translation parameters are corrected. Although modern aircraft are left-right symmetrical in most cases, the arrangement of ERS points is also left-right symmetrical in theory, but in actual operation it is obviously impossible to be absolutely accurate. So how do you plan to deal with the situation where the rotation parameters change?"

Yang Liang: “…”

"Mr. Yang Liang, your method uses measured data to optimize calculations, which will inevitably introduce noise data. How do you plan to remove this interference?"

Yang Liang: “…”

"besides……"

Sweat was pouring down.

It's not even just Yang Liang.

Even Zhou Shuwan turned his head slightly, looking at the figure on the screen not far away with a look of help...