Riding the wind of rebirth

The Institute of Applied Physics and Computational Mathematics, the name sounds related to computers and mathematics. There is no doubt that they are looking for Xiao Miao for something.

The place was really remote. Zhou Zhi saw a mountain on the road and asked, "Where is that?"

“Oh, that’s Baiwang Mountain.”

"This is Baiwang Mountain. Are we all running to the north of the Summer Palace?"

"Mr. Zhou Zhi seems to know a lot about this. Have you been to our hospital before?"

"No," Zhou Zhi smiled, "I just read a few local chronicles about the capital, until I heard that Baiwang Mountain blocks the West Lake in the south and connects to Yanping in the north. According to legend, if you walk a hundred miles from the foot of the mountain to the south towards the capital, you can still see the peak when you look back, so it is called 'Baiwang'. In the past, Lady She watched Yang Liulang go down the mountain to fight against the Liao Dynasty, and there is also a 'Wangertai' on the mountain."

"Yes!" Xiao Qian nodded: "Our unit often goes to that mountain for training, and there is indeed a lookout tower on the mountain."

The scenery in this area is actually quite nice. There are tall poplars on both sides of the road. Behind the poplars is an artificial canal with clear water and green grass beside it. It is the main water diversion line from Miyun to Beijing - the Beijing-Miyun Canal.

A few kilometers after passing Baiwang Mountain, they arrived at a unit where soldiers were standing guard. Seeing Xiao Qian in the passenger seat, they opened the gate and let the vehicle in.

After getting off the car, Zhou Zhi looked around and found that this place looked similar to many old research institutes, a red brick Soviet-style building, not small in scale but not high in height. There were several buses parked in the yard, which should be used to pick up and drop off employees to and from get off work.

This is not necessary in Shudu, as Clover can reimburse the taxi fares, because no matter whether you go home from Shuda or Digital Plaza, the taxi fare is unlikely to exceed 15 yuan.

The capital is different. It is too big. It is basically located within the fifth and a half ring road of later generations. There are no commuter buses, so people don’t have to go home.

Seeing Zhou Zhi's eyes on the bus, Xiao Qian said, "The institute has its own guesthouse, the conditions are pretty good, don't worry."

That means I can stay here and don't have to take the bus back to the city with everyone else to find a hotel.

"Both food and lodging can be taken care of. If your units provide daily allowances for business trips, our guesthouse can also issue you a certificate that you can take back to your units to exchange for allowances."

This is also an interesting thing. In later generations, when people go on business trips, they basically find their own hotel to stay in, and then there is a reimbursement system according to the regulations of the unit.

The situation is somewhat different now. Although some units have implemented this system, business trips to Beijing often encounter trouble.

First, hotels in Beijing are much more expensive than those in second- and third-tier cities. Second, you may not be able to book a hotel, so many units have set up a guesthouse system to solve the problem of non-local employees coming to Beijing for study or business trips.

According to the document regulations, people who come on business trips will eat and stay in the guesthouse during the trip and do not need to pay extra money. At the end of the trip, they only need to pay for the ticket home, and after returning to the unit, they only need to reimburse the ticket. Then they can get the business trip allowance given by the unit according to the number of days of the business trip.

It is indeed very convenient, but it increases the tertiary industry burden of the units with guesthouses. In later generations, this practice was gradually eliminated. Except for big cities such as the capital, only large units retained it.

"Oh, as long as we can solve the problem of food and accommodation." Zhou Zhi nodded: "You don't need to get a certificate."

They walked into the building's gate and passed through a long corridor. Although it was an old red brick building, it was equipped with an elevator. Xiao Qian took the two of them into the elevator and pressed the third floor button. After going out, they walked a long distance and came to a place similar to a small classroom.

"Xiao Zhang, the people are brought to you." Xiao Qian said to a young man in the room.

The young man came over excitedly and shook hands with Mai Xiaomiao and Zhou Zhi: "Teacher Mai, Teacher Zhou, hello, I am Zhang Weiting from the Institute of Computational Mathematics. Director Sun and Director Qin are waiting for you."

In fact, until now Zhou Zhi didn't quite understand why he came here. He followed Zhang Weiting to another office and saw Qin Haifeng chatting with an old man. He was relieved: "Uncle Qin." When he saw the person Qin Haifeng was chatting with, he took a breath of cold air: "Academician Sun?"

"Oh? Xiao Zhou still knows me?" The old man looked at Zhou Zhi kindly: "Did Director Qin tell you about me?"

"I didn't." Qin Haifeng immediately shook his head: "It's a habit to keep secrets, so I didn't say anything that shouldn't be said. I didn't mention your name to this kid."

"In 1988, People's Literature published a non-fiction article about the development of my country's nuclear industry. Your name was on it." Zhou Zhi said admiringly, "That was the first time your name was declassified. After that, whenever I saw reports about you in newspapers, magazines, or on television, I would pay attention to it."

"Mr. Deng said that without you, there would be no nuclear industry. Legend has it that the calculation data for my country's first atomic bomb was calculated by researchers using an abacus, and you were the one who calculated the data using an abacus."

Academician Sun's full name is Sun Liangdong. He waved his hand and said, "The report is really exaggerated. We did use an abacus for calculations, but it was not the main method. We mostly solved the problems manually with advanced mathematical tools. If we really used an abacus to calculate the data for the atomic bomb, Xiao Miao would probably laugh at us."

"Hello, Grandpa Sun, hello, Uncle Qin." Mai Xiaomiao greeted them both politely.

"Xiao Miao, have you prepared all the information?" Qin Haifeng asked.

"Yes, I'm ready." Mai Xiaomiao nodded.

"Wait, what information?" Zhou Zhi was confused.

"You are a liberal arts student. Do you know the Venturi phenomenon?"

"Uh, I don't know." Zhou Zhi admitted honestly.

"Do you know the Bernoulli effect?"

"You probably know that an increase in flow rate is accompanied by a decrease in fluid pressure, right?"

"Yes, Bernoulli's principle is very common. In fact, the Venturi effect is what we see most often."

"The Venturi effect was discovered by Italian physicist Venturi. This effect is manifested in the phenomenon that when a restricted flow passes through a reduced flow cross-section, the flow velocity of the fluid increases, and the flow velocity is inversely proportional to the flow cross-section."

"When the fluid blows over the obstruction, the air pressure near the port above the leeward side of the obstruction is relatively low, which produces an adsorption effect and causes the air to flow, and people invented the Venturi tube."

"The principle of the venturi tube is actually very simple. It changes the fluid from coarse to fine to speed up the flow of the fluid. However, the price is that the fluid forms a 'vacuum' area on the back side of the venturi tube outlet."

"The flow velocity is high where the cross-section is small, and low where the cross-section is large. This is the principle of the Venturi tube." Qin Haifeng said, "However, this principle is exactly the opposite when the fluid speed reaches transonic speed. The larger the cross-section, the faster the flow velocity. This effect is called the Laval effect, and it was discovered by a physicist named Laval."

"So we can design a venturi with a narrow throat, because the Venturi effect is 'the flow velocity is high where the cross-section is small, and the flow velocity is low where the cross-section is large', so as long as the pressure and flow rate are appropriate, when the narrow throat is small to a certain extent, the flow rate can exceed the speed of sound."

"However, transonic fluids no longer follow the Venturi effect when moving, but on the contrary, follow the Laval effect, which states that 'the larger the cross-section, the faster the flow rate.' Therefore, as long as we design a bell mouth behind the narrow throat, we can increase the flow rate of the fluid to several times the speed of sound."

"Rocket propulsion nozzle!" Zhou Zhi immediately thought of this thing based on the shape and function of the thing described by Qin Haifeng. (End of this chapter)