Sister Hui Ye Wants Me to Be Reliable

No one was able to answer Shi Zhu's question involving cold knowledge - besides, the question was still very vague.

He had no choice but to bite the bullet and call the Jiangdong District Office where the exhibition hall was located.

"Uh... hello, I would like to ask one thing about the bell that plays at five o'clock in the evening..."

Even the people from the general affairs management department of the district office rushed to trouble this kind of cold knowledge.

Fortunately, they weren't too busy. Shizhu's call was transferred to several departments all the way, and finally transferred to the disaster prevention department.

"The bell you asked about is called the disaster prevention administrative wireless broadcast." The person who answered Shi Zhu's question was a middle-aged woman with a very kind voice, "In case of an earthquake or fire, rely on that Emergency broadcast. It is fixed at [-] pm every day, and it is not called a bell, but a test broadcast."

Shi Zhu suddenly remembered that this term was indeed mentioned in the school's disaster prevention education curriculum.

I actually forgot...

"Then, can you tell me where the amplifiers used to play the test broadcast are installed in the capital?"

"Which places?" The middle-aged woman hesitated, "There are more than 40 in Koto District alone, counting the entire area of ​​Tokyo, the number is a bit too large..."

"Four..." Shi Zhu almost couldn't stand still.

Indeed, such a request, even if you are not busy, will still cause a lot of trouble for the other party, let alone this time.

"Then... please tell me Koto District, Edogawa District, Sumida District, Chuo District—"

He hurriedly centered on Jiangdong District, selected several nearby areas, and applied to the other party.

But even if the scope is reduced, the number is still considerable.

It involves all fire stations in these administrative divisions, almost all public schools, and parks.

Shi Zhu lay on the table, and marked the locations one by one according to the patient civil servant in the disaster prevention department.

By the time I finished marking the map in a hurry, it was almost the closing time of BIG SITE.

As soon as the fingers were loosened, the ballpoint pen slid down on the paper, and Shizhu moved her shoulders to relieve the soreness and fatigue.

Drawing circles is a little easier than signing, so it's not a big problem.

"Senior, I have estimated the number." Ishigami raised his head and told him the number Shi Zhu requested.

Shizhu wrote down three numbers in the blank area of ​​the map, and Kasumigaoka said, "Are you really sure that you can find Yinglili through these numbers?"

"There's no way to guarantee [-]%, but it's worth a try. It's better than searching blindly." Shi Zhu said, "By the way, what is the approximate speed of sound in the air under the current season, temperature, and air pressure?"

The speed of sound is generally 340 meters per second, but the specific value will fluctuate according to changes in temperature and air pressure.

"It's about 346 meters per second." Ishigami continued to report the number.

"Sonic?" Kasumi Hill asked.

Shizhu pressed her hands on the map, "In Yinglili's voice message, you can hear the bell ringing between speeches. And the bell will ring on time every day at five o'clock in the afternoon."

He swallowed, "According to the civil servant's answer, all the loudspeakers of this kind of radio will sound at the same time according to the established procedure. In other words, the farther away the location, the slower the sound of the radio will be transmitted." .Just calculate the number of seconds when those bells sounded late, and then multiply by the actual speed of sound, you can know how far away Ying Lili is from the broadcast. You can hear three bells in the message, ringing at short intervals once……"

"Just based on this?" Xia Zhiqiu was amazed, but couldn't help but believe that this young man who was not tough at all, "The time interval of the bell is very short, right? And at the same distance, there will be many loudspeakers, isn't it?

"So next, we need to bet on how far Yinglili of the indoor school can walk with his feet." Shi Zhu smiled weakly, and drew three small circles on the map according to the calculated distance with a compass.

It is precisely because of this that he gave up those areas that are far away from Jiangdong District.

The error in the number estimated based on time and sound speed is quite large, and Shi Zhu doesn't think it will be so lucky that she can find Yinglili's location in the area where the circles corresponding to the three numbers overlap.

But even so, there is a need to try it.

When the guy changed his mobile phone, he listened to his persuasion and bought a mobile phone that was excellent in every way, including the sound pickup performance. It was a great help.

"Unexpectedly, at a critical moment, I will gamble on luck." Xia Zhiqiu said.

"If possible, I don't want to gamble." Shi Zhu pressed her forehead, "But I still hope that even if she is depressed, she will subconsciously go home. And—"

Shizhu turned on the phone and called Sayuri Sawamura.

The Sawamura couple, who love their daughter too much, can receive the GPS location of Yinglili's mobile phone on their mobile phones.

Although most of the time they would not check at all to take care of Yinglili's privacy.

"Aunt Sayuri, I'm Shizhu." After the call was made, Shizhu immediately explained the situation, "... Yinglili's phone is turned off, and I'm going to find her. I want to ask when and when was the last time Yinglili's mobile phone uploaded the GPS location Place?"

Sayuri on the other end of the phone was surprised at first, knowing the priorities, she immediately told Shizhu the location, and agreed that if Yinglili could not be found before [-] o'clock, she would search for it through her acquaintances and with the help of the police.

"I won't trouble Auntie to that extent." Shi Zhu could understand, but felt it was too exaggerated, so she just said that.

"I also believe in Xiaodian." Sayuri replied solemnly, then hung up the phone.

Unfortunately, the last time Yinglili was detected by GPS was already back around four o'clock, about an hour earlier than the time of the voice message.

After that, she took the initiative to cut off the data upload.

Shizhu's finger landed on the map, and moved along the national road where Yinglili's house was located towards the venue. The last GPS detected position was indeed in between, but it was still far away from the three circles.

Finally, Dianthus' fingers stopped where the circles drawn by the compasses overlapped, with a blue band running through it.

It was a certain river in the city.

If Ying Lili subconsciously walks towards home, passing the river is also a reasonable route.

And being able to hear the bell so clearly is not only due to the excellent sound pickup performance of the mobile phone, but also because the surrounding environment is open and unobstructed.