abstract

With the progress of society, the development of science and technology and the improvement of living standards, cars, as people's means of transportation, began to enter the homes of ordinary people. Especially with the acceleration of urbanization, more and more cars appear around us, traffic safety problems become more and more prominent, all kinds of safety hazards are invisibly magnified, and people's life safety is also facing more severe challenges. Traditional automobile safety measures can't effectively solve traffic accidents. At present, the concept of automobile safety is gradually changing. With the progress of science and technology, automobile safety is becoming more and more refined. At present, automobile safety is divided into active safety and passive safety.

Keywords: active safety; Passive safety; New security technology;

In the 1960s, the United States required all vehicles to install seat belts and put them into law. Now, another important safety equipment has also been listed as a mandatory installation configuration by the National Highway Traffic Safety Administration of the United States-the electronic stability control system of the car body. Some experts predict that by 20 1 1 year, this technology alone will save 1 10,000 lives in the United States every year. Not only that, but now more and more technologies are integrated into cars to improve driving safety. The safety configuration of automobile is no longer a single accessory such as seat belt, but more accessories and electronic control system are integrated together to form a comprehensive system that is different from each other but crosses each other. Automobile safety technology has begun to penetrate into all parts of the car. Please see the details below.

Passive safety of automobile

1. What is passive security? Passive safety refers to the protection of the occupants in the car after the accident. Nowadays, this concept of protection extends to everyone, even objects inside and outside the car. Because the international automobile industry has stipulated very detailed test details for passive safety, to some extent, passive safety can be quantified. On the other hand, passive safety devices play a passive role in protecting passengers when a car accident occurs and the vehicle is out of control. It is hoped that the occupants in the car room will be fixed in a safe position by fixing devices, and the impact force will be absorbed as much as possible by structural guidance and collapse to ensure the safety of the occupants in the car room.

Second, the main passive safety technology:

1. pretension the seat belt.

At the moment of a collision accident, when the passenger has not moved forward, it will tighten the webbing first, immediately tie the passenger tightly to the seat, and then lock the webbing to prevent the passenger from leaning forward, effectively protecting the safety of the passenger. The characteristic of pre-tightening seat belts in the pre-tightening process is that the retractor, which plays a major role in pre-tightening seat belts, is different from ordinary seat belts. It not only has the webbing retracting function of ordinary retractor, but also can strengthen the binding force on passengers at about 0. 1s when the vehicle speed changes sharply, so it also has a control device and a pre-tightening device. There are two kinds of control devices: one is electronic control device, and the other is mechanical control device. Pre-tensioning devices come in many forms. The common pre-tensioning device is deflagration type, which consists of gas initiator, gas generator, conduit, piston, rope and driving wheel. When a car collides, the pre-tightening device is activated, and the gas initiator at the bottom of the sealed conduit spontaneously ignites, detonating the gas generant in the same sealed conduit. The gas generant immediately generates a large amount of gas expansion, forcing the piston to move upward to pull the rope, driving the driving wheel to rotate the winding reel, and the webbing is wound on the reel, so that the webbing is pulled back. Finally, in an emergency, the retractor will lock the webbing to fix the occupant's body and prevent him from leaning forward and colliding with the steering wheel, dashboard and glass window.

2. Passenger Head and Neck Protection System (WHIPS)

Whips are usually located in the front seats. When the car is rear-ended, the head and neck support will inflate quickly, and its entire backrest will lean backwards with the occupant, so that the occupant's entire back and backrest are firmly together, and the backrest will lean backwards, minimizing the force of throwing the head forward. The backrest and headrest of the seat will move backward horizontally, so that the upper part of the body and the head can be supported and protected gently and evenly, so as to reduce the impact force borne by the spine and neck and prevent the injury caused by the backward throwing of the head.

3. Airbags

It is distributed in the front (front and rear driver's seat), side (front and rear row) and roof of the car. The words (SRS) are printed on the outside of the container equipped with airbag system, and the Chinese literal translation should be "SRS". The purpose is to reduce the degree of injury of passengers in the second collision caused by inertia after automobile collision. As an auxiliary configuration of passive safety of car body, people pay more and more attention to it. When a car collides with an obstacle, it is called a primary collision, and passengers collide with internal parts of the car, which is called a secondary collision. The airbag quickly opens the air cushion filled with gas after the first collision and before the second collision, so that passengers can "jump on the air cushion" when they move under inertia, thus reducing the impact on passengers, absorbing collision energy and reducing the degree of injury of passengers. Airbags can evenly distribute the impact force on the head and chest, prevent the fragile passengers from directly colliding with the car body, and greatly reduce the possibility of injury. Airbags can effectively protect passengers in a frontal collision. Even if you don't wear a seat belt, the anti-collision airbag is still enough to effectively reduce injuries. According to statistics, when a car with airbags collides head-on, the degree of passenger injury can be reduced by as much as 64%, and even 80% of passengers are not wearing seat belts! As for the collision between the side and the back seat, it still depends on the role of the seat belt. In addition, when the airbag bursts, the volume is only about 130 decibels, which is within the human body's tolerance range; 78% of the gas in the airbag is nitrogen, which is very stable and harmless to the human body; The powder brought out during the explosion is lubricating powder to keep the airbag from sticking together in the folded state, which is harmless to human body.

4. Safe body

A well-designed car body structure is the subject of passive safety. Research shows that in road traffic accidents, most of the collision energy is absorbed by the car body. The performance of a safe car body is that the structure of the car room is firm, and the deformation is very small in the event of an accident, which fully guarantees the living space of the internal occupants; At the same time, the front and rear parts of the car body can deform and absorb energy during collision, reducing the impact on the occupants. The latest seat belts have added a pre-tightening device and force limiting protection measures, that is, when the sensor detects a collision, the pre-tightening device tightens the seat belt by blasting energy (much less than the energy of the airbag, so the airbag is regarded as the only device that releases energy first), thus prolonging the energy absorption time and distance of the seat belt. Force-limiting protection is to relax the seat belt properly when the occupant is subjected to the compression limit to avoid unnecessary injuries.

5. Smart airbags

The working principle of airbag is that when the front of the car is hit by a certain force, the safety system will trigger a chemical reaction similar to the explosion of small-dose explosives, and the airbag hidden in the steering wheel will inflate and pop up in an instant, paving the way for the body of the person in the car to collide with the equipment on the car due to inertia, so as to reduce the impact on the body. Because the cushioning function must be completed at the moment of the accident, the airbag must be ejected at an extremely fast speed. This can effectively protect the life safety of the driver.

Third, the new passive safety technology:

1) Body and door that can withstand collision and absorb energy.

Further improve the car body that can withstand frontal and side impact and absorb energy, improve the door design, increase the cross beam to make it have better side impact resistance, and adopt sandwich steel plate with foam filler in the middle.

2) Side airbag

Side airbags are arranged on the side of the headrest and the back of the chair. When a side collision occurs, the airbag will expand to absorb the energy of the side collision, thus protecting the safety of the occupants.

3) Occupant protection system

When it is predicted that the accident is inevitable, the central microcomputer control system will instruct the seat belt to tighten, make the seat move backward along the slide rail, make the retractable steering column shrink into the instrument panel, and put the airbag into operation.

4) Emergency door lock release device

When the vehicle collides, the sensor has confirmed the collision, and the system can immediately release the door pin, thus quickly opening the door.

5) Fire extinguishing system

After the sensor in the engine room detects the fire, the fire extinguishing device will start the automatic fire extinguishing. If the device fails, the hood will be automatically released to extinguish the fire from the outside.

6) Driving recorder

Similar to the black box on the plane, it can record all kinds of information about the vehicle and environment before and after the accident, reproduce the development process that led to the accident, analyze the cause of the accident, and provide reliable information for future prevention.

7) Automatic emergency notification system

Through this system, vehicles can get in touch with the radio station in charge of traffic management in time, and the radio station can know the location of the accident vehicle, the accident situation and the main injuries of passengers, and can inform relevant departments and personnel to go to the accident site in time to carry out rescue work. For example, the RescueCar technology of Ford Motor Company can report to the relevant departments immediately after the collision accident and forward the important information of the wounded on the way to the scene.

Automobile active safety

1. What is active security? Active safety refers to the measures to control the automobile safety system as freely as possible. No matter the braking and acceleration in a straight line or the impact direction from left to right, it should be as smooth as possible, without deviating from the established driving route and affecting the driver's vision and comfort. Such a car, of course, has a relatively high ability to avoid accidents, especially to ensure the safety of the car in an emergency. Active safety systems usually include the following systems.

Second, the automobile active safety technology:

1. anti-lock braking system

It calculates the wheel slip rate at that time through the speed of each wheel detected by the sensor, so as to know whether the wheel is locked, and then commands the actuator to adjust the braking pressure, so that the wheel is in an ideal braking state (fast locking but not completely locking). Correctly understand the function of ABS: in the case of emergency braking, it can keep the vehicle from being locked out of control, keep the steering ability and avoid obstacles. Generally speaking, it cannot shorten the braking distance.

2. Electronic braking force distribution system

Must be used in conjunction with ABS. At the moment of braking, it can sense and calculate the different ground on which the four tires are attached, and obtain the friction value, and distribute the corresponding braking force according to the different friction value of each wheel to avoid the danger of slipping, tilting and rollover caused by the different braking force of each wheel.

3. Electronic stability program

It is actually a traction control system. Compared with other traction control systems, ESP not only controls the driving wheel, but also controls the driven wheel. It realizes the smooth running of vehicles by actively intervening in danger signals. For example, a rear-wheel drive car often turns too much, and the rear wheel is out of control, and ESP will slow down the outer front wheel to stabilize the car; When the steering is too little, ESP will slow down the inner rear wheel to correct the driving direction, thus correcting the tracking direction.

4.EBA (Emergency Brake Assist System)

The computer judges the driver's intention to brake this time according to the detected braking action on the brake pedal. In case of emergency braking, the braking system is instructed to generate higher oil pressure to make ABS work, which can generate braking force faster and shorten braking distance.

5. Lane departure warning system

The system provides intelligent lane departure warning. When the driver unconsciously leaves the original lane (no turn signal), it can give an alarm 0.5 seconds before leaving the lane, which provides the driver with more reaction time and greatly reduces the collision accidents caused by lane departure. In addition, the use of LDWS can also correct the driver's habit of not playing turn signals. Its main function is to assist the situation of inattention caused by excessive fatigue or long-term monotonous driving.

6. Traction control system

TRC is a device to prevent the wheels from idling when the vehicle is started or accelerated. On slippery roads such as snow and ice, when the vehicle starts or accelerates rapidly, the wheels are easy to idle. TRC can sense the idling of the driving wheel when the vehicle starts or runs, control the braking oil pressure of the driving wheel and the power output of the engine, provide the most suitable driving force, prevent the idling of the driving wheel, and improve the driving safety on wet roads.

7.VSC body stability control system

The front wheel sideslip properly brakes each wheel tire to make the vehicle face inward. At the same time, the engine output is controlled so that the vehicle will not rush out of the driveway. The rear wheel skids to brake the tire on the wheel side, so that the direction of the car can control the output of the engine at the same time, and the car body can be stabilized.

8. Brake assist system

As an auxiliary braking control system, the brake assist system can improve the braking force in an emergency. According to the speed and the force acting on the brake pedal, the system can judge what kind of brake the brake belongs to. When the system judges the emergency braking, even if the driver's braking force is weak, the system can generate a larger braking force through automatic control.

9. Tire pressure monitoring

National Highway Traffic Safety Administration (NHTSA) requires that by 2003, all American passenger cars with annual vehicle weight less than or equal to 4536kg must be equipped with tire pressure monitoring system. Since then, BMW has used this system in all cars. The driver can judge whether the tire pressure is normal through the in-vehicle early warning system, which firstly avoids driving deviation caused by tire deflation, and secondly ensures the safety of passengers when driving at high speed.

10. Stop warning/stop image/external camera

The technology of reversing warning is used to warn the cars or objects in your blind area during driving and parking. Usually the system will respond when you are driving; It may cause the warning sign in the rearview mirror to flash and sound a warning sound. The system is a short-range detection system. For example, the rearview mirror of Shanghai GM Buick LaCrosse is equipped with this function. There will be an icon in the shape of a car on the left side of the rearview mirror, and the warning sign of the front/rear radar will give the driver a visual and auditory warning when an obstacle is detected.

The combination of the reversing image and the rearview camera not only protects your car, but also avoids the accidental injury to children and animals when reversing. Reversing has changed from tilting the rearview mirror downward or giving an audible warning to real-time viewing. The new generation of technology includes a camera, which can work with the navigation system to take a wide-angle picture of everything behind you, and then reflect it on the screen in the car, thus helping you back up or hitch a trailer.

1 1. Chip anti-theft system

Property safety has been paid more and more attention. The theft of hundreds of thousands of cars will cause great losses to the owners. Manufacturers have also racked their brains to add more safety precautions to cars. General Buick LaCrosse not only adds Passkey III security anti-theft system to the ignition key, but also improves the structure of the trunk, changing it to remote lock core anti-theft mode, which greatly reduces the probability of being stolen and pried, and gives the owner the greatest protection in terms of property. Automatic cruise technology

When the cruise system is started, the car will keep a fixed speed and move forward automatically without stepping on the accelerator. This can reduce the driver's fatigue in long-distance driving and is most suitable for use on expressways. However, in any case, the driver must brake and slow down immediately to prevent accidents. Therefore, the driver must be ready to brake at any time. After braking, the cruise system will automatically lose its function, and the cruise speed must be reset after re-acceleration. The new cruise system has a highly intelligent function and can automatically adjust the speed.

When a car with a new cruise system is driving in the street, the driver can put his feet far away, and the vehicle can slow down and accelerate automatically, just like an invisible driver is driving for you. What the human eye can see and what the automatic cruise system can detect is what the driver can't see, and it can also find. The GPS positioning system it carries will always remind the automatic cruise system of objects that may suddenly appear within a square kilometer.

12. Integrated chassis control system

The function of the new integrated chassis control system is to prevent the driver from hitting his head or being thrown out of the car when driving or turning quickly. The control systems such as braking, suspension, steering and power transmission are "electrically connected" through the central chassis controller, and all systems are coordinated through complex control operations, so that the overall performance and stability of the vehicle can reach the best level and the collision caused by centrifugal force during bumps and sharp steering can be reduced.

13. automatic induction headlights and/or night vision assistance system

The automatic induction headlights are affected by the ambient light around the vehicle, and the system will automatically identify and judge. When the light is insufficient in rainy and foggy weather, the headlights will automatically light up, providing a safer driving environment for drivers. Later, the manufacturer extended to the adaptive headlight system, which is more advanced and will be adjusted according to the direction (the vehicle will turn on the turn signal when turning). They can also be speed-sensing headlights (which can change the length or height of the light beam) or compensate for ambient light.

Night vision systems can take different forms, such as basic infrared headlights or thermal imaging cameras. But no matter which technology is adopted, the function is the same: at night or in the case of unclear vision, it helps you to see the road farther away and identify animals, people or trees on the road near 1000 feet. Images are formed on the display screen of the cab, so that obstacles that are difficult to see with the naked eye can be controlled by the driver in advance. At present, the night vision system developed by Bosch company has the above functions, but the price is very expensive. Even ultra-luxury cars are basically optional systems at present. I believe this more advanced system will also be selected by mid-to high-end cars in the near future.

Third, the new technology of active safety:

1) system for detecting road surface and environmental conditions.

Use sensors or cameras to detect road conditions (dry, wet or snowy, whether there are obstacles, etc.). ); Detecting the distance between surrounding vehicles and obstacles and the relative speed of vehicles; Detect the surrounding pedestrians and traffic conditions, and use infrared monitoring system to indicate the pedestrian conditions at night on the display screen. These tests constantly provide drivers with information or warnings of dangerous conditions.

2) dozing warning and wake-up system

Using the small camera and infrared scanning device installed on the dashboard in front of the driver, the change of the driver's facial expression is monitored, and whether the driver is dozing off is judged by microcomputer processing. When the driver is inattentive and in a dangerous state, it will give out a warning sound, and at the same time it will automatically emit a refreshing fragrance from the air conditioning system.

3) altitude adaptive cruise control system

After the cruise control function is started, the system can automatically slow down or accelerate according to the speed of the front vehicle and the distance of the rear vehicle. Compared with the traditional system, the system adds a road condition sensing system, and uses a higher performance microcomputer to control the braking system and adjust the oil supply of the engine.

4) Emergency braking early warning system

Generally, it takes about 0 .8s for a driver to move his foot from the accelerator pedal to the brake pedal during emergency braking. The system can monitor the driver's early action of emergency braking. When the acceleration of the accelerator pedal reaches a certain value, the brake light will light up to warn the driver of the vehicle behind, so that the driver of the vehicle behind can respond to the situation of the vehicle in front for 0 .8s more. Equipped with this system, the phenomenon of rear-end collision can be reduced.

5) Fire or low tire pressure alarm system

The system can send an early warning signal to the driver at the beginning of the fire and when the tire pressure is too low, so as to eliminate hidden dangers as soon as possible.

6) Intelligent headlamp servo system

Intelligent adaptive headlamp system not only adopts anti-glare glass, special-shaped headlamp and other measures, but also provides lighting that is more convenient for observing the road ahead according to various driving conditions. AFS system can automatically adjust the irradiation axis of low beam and corner light to the left and right sides according to the turning angle and driving speed, which makes it easier for drivers to see the road ahead when turning at night and improves driving safety.

7) Active driving safety system

The system, also known as the driving dynamics regulation system, can not only maintain and improve the basic functions of ABS and ASR, that is, the stability of the automobile in the critical state of longitudinal dynamics; Moreover, it can obviously reduce the sideslip danger of the automobile under various working conditions, that is, it can also play a stabilizing role in the critical state of lateral dynamics. Take traction control system (TCS) as an example, TCS(TractiOn COntrOlSystem) is also called drive acceleration slip regulation. When a car brakes on a smooth road, the wheels will slip and even the direction will be out of control. Similarly, when auto start or sudden acceleration occurs, the driving wheels may slip, and the direction will be out of control on smooth roads such as ice and snow, leading to danger. So control its traction. When TCS relies on electronic sensors to detect that the speed of the driven wheel is lower than that of the driving wheel (which is the characteristic of slipping), it will send out signals to adjust the ignition time, the opening and closing time of the injector and reduce the valve opening, thus reducing the engine speed and output torque. Or control the downshift and brake the wheel, so that the wheel will not slip. TCS can improve driving stability, acceleration and climbing ability.

Another example is Electronic Stability Program (ESP), which is actually the traction control system. Compared with other traction control systems, ESP can control not only the driving wheel but also the driven wheel. ESP generally needs to install steering sensor, wheel sensor, sideslip sensor and lateral acceleration sensor. The system has the function of supporting ABS and TCS. By analyzing the vehicle running state information from various sensors, the rectification instructions are sent to ABS and TCS to help the vehicle maintain dynamic balance. ESP can keep the best stability of the vehicle under various working conditions, and the effect is more obvious in the case of oversteer or understeer. Research shows that ESC technology reduces 5000 ~ 8000 traffic accidents in the United States every year, and the driver's ability to control the car in an emergency is improved by 34%.

8) Satellite positioning and navigation system

The system can provide drivers with relevant traffic information, such as the position of the car when driving, traffic accidents and congestion in the front route, etc. Instruct drivers how to reach their destination smoothly along the best route. The system can improve transportation efficiency, make driving easier and contribute to traffic safety.

9) Active anti-collision technology

Active collision avoidance technology is an important research direction in the field of automobile active safety. Its principle is to monitor the road traffic around the vehicle by means of radar and red perimeter. Once two cars are in danger of collision, they will send a warning signal to the driver, or automatically take measures such as braking and steering to avoid collision. Nissan, which has made great achievements in the research and development of active safety technology in recent years, recently introduced two active anti-collision technologies for vehicles, namely, anti-side collision and anti-rear collision technology, in order to strengthen the protection performance of Nissan's models for passengers. These two technologies, together with the lane departure warning system and the auxiliary distance control system previously introduced, can well embody the safety concept of Nissan's "safety barrier" and provide multi-angle protection for vehicles and occupants.

The anti-side collision technology is to install sensors on the side of the car body. When there is a car in the adjacent lane, if the driver starts to change lanes, he will give a warning with images and sounds, and at the same time, he will control the brakes of each wheel separately to generate the steering force of the vehicle to help the driver drive the vehicle away from the adjacent vehicle. As for the rear-end collision prevention technology, the rear situation is monitored by the sensor at the rear of the car. If the sensor detects the possibility of rear-end collision, it will automatically warn the driver or temporarily take over the control of the braking system to avoid being rear-ended. In recent years, Nissan has made great achievements in the field of active safety technology, and has developed a number of world-first active safety technologies, which have played a very good role in reducing road traffic accidents.

10) safe driving direction control system

When the vehicle deviates from the correct driving route, the white route sign signal captured by the system camera is abnormal, warning the driver or automatically returning to the original route. When a vehicle wants to change its route, it will remind the vehicles behind it to avoid a collision accident.

1 1) Steering deceleration adjustment system

When a vehicle encounters a curve, it often happens that the vehicle hits a road sign or rolls over because the driver is unfamiliar with the road, or is inattentive, or the speed is too fast. The turning deceleration adjustment system can detect the turning radius and curvature of the turning vehicle passing through the road surface, and reduce the speed of the vehicle accordingly.

Development trend of modern automobile safety technology

Automobile safety design should be considered as a whole, not only to minimize the probability of occupant injury when an accident occurs, but also to help drivers avoid accidents under relaxed and comfortable driving conditions. Modern automobile safety technology includes active safety technology and passive safety technology. Passive safety technology and active safety technology are important guarantees to ensure the safety of automobile occupants. In the past, passive safety systems were mainly considered in automobile safety design, such as seat belts, airbags and bumpers. Nowadays, car designers pay more attention to active safety design, so that cars can take active measures to avoid accidents. This car is equipped with an automobile avoidance system, including sensors such as anti-collision radar, Doppler radar and infrared radar installed in various parts of the car body, blind spot detectors and other facilities, which are controlled by a computer. In dangerous situations such as overtaking, reversing, lane changing, heavy fog, rainy days, etc., it can provide drivers with necessary information around the car at any time in the form of sound and light, and automatically take measures to effectively prevent accidents. In addition, a lot of information about drivers and vehicles can be stored in the memory of the computer to monitor and control drivers and vehicles. For example, according to the Japanese government's "Advanced Automobile Plan to Improve Automobile Intelligence and Safety", Toyota Advanced Safety Automobile successfully developed by Toyota Company of Japan includes driver drowsiness warning system, tire pressure monitoring warning system, engine fire warning system, headlight automatic adjustment system, blind spot monitoring system, information transmission system between automobiles, road traffic information guidance system, automatic braking system, emergency call (SOS) parking system, fire extinguishing system and all-round airbag system.

In the development history of 100 years, the research of automobile safety performance and the application of new technologies are also changing with each passing day. From the initial bumper shock absorption system, passenger seat belt system and airbag to automobile crash test, wheel anti-lock braking system (ABS) and drive acceleration slip adjustment (ASR), to the research of safety rearview mirror and child seat system without blind spots and neglected errors, automobile safety can be improved more and more. Especially in recent years, with the rapid development of science and technology, more and more advanced technologies have been applied to automobiles. At present, all countries in the world are using modern high-tech technology to step up the development of automobile safety technology, and a number of cutting-edge technologies and new products related to automobile safety are loaded and used one after another, making future automobiles safer.

One of the important development directions of automobile electronic control in the future is the field of automobile safety, which will develop in several directions: (1) developing various automatic anti-collision systems by using radar technology and vehicle camera technology; Using near infrared technology to develop various safety systems that can monitor the driver's behavior; High performance tire integrated monitoring system: adaptive automatic cruise control system: driver identification system: airbag and ABS/ASR. With the wide application of more advanced intelligent sensors, quick response actuators, high-performance electronic control units, advanced control strategies, computer network technology, radar technology and the third generation mobile communication technology in automobiles, modern automobiles are developing towards more intelligent, automated and information-based mechatronics.

conclusion

The application of electronic control technology, microcomputer processing technology and sensing technology not only improves the control accuracy of vehicles, but also makes the safety technology develop by leaps and bounds. The coordinated and integrated development of active security technology and passive security technology is an irresistible development trend. Reducing the driver's labor intensity and effectively protecting passengers and pedestrians in the event of an accident also play an important role in safety. It is believed that the future safety technology can further improve the safety of vehicles and escort more drivers, passengers and third parties.

Take the exam and contribute.

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[3] Yu Zhisheng. Automobile Theory (3rd Edition) [M]. Tsinghua University Publishing House, 2004.

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thank you

From topic selection to data collection, from writing to repeated revision, I experienced joy, noise, pain and hesitation, and my mood was so complicated in the process of writing the paper. Now that I have the final draft of this graduation thesis, my complicated feelings have vanished, and I even have a little sense of accomplishment. It was like being at a grand awards party. I watched others take the stage one after another to receive the prize, but I never got my name. After a long time, a guest finally called my name. At this time, I forgot the long and boring waiting time, walked on the stage happily, and then couldn't wait to express my feelings and express my feelings. This graduation thesis is my stage, and the following words are my heartfelt thanks and feelings after a little sense of accomplishment:

I want to thank, thank my teacher very much. They are easy-going and enthusiastic, and their studies are rigorous and serious. In small talk, she can always encourage you like a confidant, and she will always be strict with you on the writing and wording of the paper with "professional standards". From the beginning of the topic selection and the determination of the topic, to the repeated revision and polishing of the final paper, the teachers always give me in-depth and meticulous guidance with a serious and responsible attitude, helping me to develop research ideas, giving careful guidance and enthusiastic encouragement. Thanks to the selfless help and enthusiastic encouragement of teachers, my graduation thesis can be successfully completed. Thank you, teacher.

Ok, this is perfect enough, I hope to adopt it! ! ! I hope I can get extra points! ! !