25th place: Bank of America Building.
The Bank of America Building (also known as the library building and the first interstate world center) is located at 633 West Fifth Street in downtown Los Angeles, California, USA. It is the tallest skyscraper in North America west of Chicago and the tallest building in California. In addition, the u.s. bank tower is also the tallest building, with a helicopter airport on the top floor (built according to the building law of Los Angeles). With a height of 10 18 feet (3 10 meter), the Bank of America Building is one of the tallest skyscrapers in the world (ranked 22nd in 2005). Before the completion of Taipei 10 1, the Bank of America Building was also the tallest building in the main seismic activity area, and the building itself was designed to withstand an earthquake with a magnitude of 8.3 on the Richter scale. The Bank of America Building is 73 stories high and has two underground parking lots. It was designed by I.M. Pei's architect Henrey N. Cobb, with a total cost of $350 million.
25th place: Bank of America Plaza in Atlanta
The Bank of America Plaza is the tallest building in the southern United States. The whole construction process only took 14 months, which is one of the fastest buildings in 1000 feet. Covering an area of 3.7 mu, the front is at a 45-degree angle with the adjacent street, so the outline seen from north to south is the largest. At the top of the building is a pyramid-shaped steel frame, forming a 90-foot-high spire with an area of 450 square feet and decorated with 23 gold leaves. The Bank of America Plaza is also the first building to win the "Energy Star" energy efficiency award. Four architectural schemes were designed for the building, including the twin towers, and the current scheme was finally adopted.
24th place: Chrysler Building, New York
Many ancient rulers built monuments for themselves, and skyscrapers in the early 20th century are regarded as something similar to them in modern times. These buildings are used to show off their power and wealth.
The Chrysler Building was built by the famous architect Allen entrusted by Walter P. Chrysler, the founder of Chrysler Automobile Manufacturing Company. Established in 1926- 193 1 year, located in new york, USA. It is the first skyscraper with a height of over 305 meters. Left: The metal eagle dripper stares at the street below from the upstairs of 6 1. Walter P. Chrysler asked them to be decorations on the radiator cover of the car as a symbol of his brilliant automobile manufacturing empire. The actual height is 3 19 meters, which is 37 meters higher than the competitor Wall Street Building 40, which is 282.6 meters. 1930, Wall Street Building 40 surpassed Chrysler Building with a height of 282.6 meters, but Chrysler Building added a 37-meter-high metal tower, making it the tallest man-made building in the world (higher than the Eiffel Tower). 1 1 month later, the Empire State Building topped the list, with a height exceeding.
23rd place: Burj Khalifa.
The main height of the hotel is 32 1m, which is built on an artificial island by the sea. It is a sailboat-shaped tower building with 56 floors and a height of 32 1m, designed by a famous British designer. The hotel adopts the architectural form of double-layer membrane structure, with light and elegant shape, strong membrane structure characteristics and modern style. It has 202 duplex rooms and a 200-meter-high restaurant overlooking Dubai. Only when you have been to Burj Khalifa Hotel can you appreciate the true meaning of "glory". Its atrium is golden, and its most luxurious presidential suite of 780 square meters is gorgeous and extraordinary. 25th floor, gilded furniture, a cinema, two bedrooms, two living rooms, a dining room and a dedicated elevator. The room area ranges from 170 square meters to 780 square meters. The price of a seven-star hotel is definitely high, with a minimum of $900 and a presidential suite of $65,438+8,000. This hotel has 8 BMWs and 2 Rolls-Royce cars, which are specially designed for in-house passengers and can go directly to and from the airport. You can also take a helicopter from the airport on the 28th floor of the hotel and spend 15 minutes overlooking the beautiful scenery of Dubai. If guests want to eat in a seafood restaurant, they will be sent to the restaurant by submarine so that they can enjoy the wonders of the sea before eating.
22nd place: Pyongyang Liu Jing Hotel.
Liu Jing Hotel in Pyongyang, North Korea is an unfinished skyscraper. Liu Jing Hotel is named after the ancient Korean name "Liu Jing". The building is a triangular pyramid building with a slope angle of 75 degrees, a height of 325m 105 floor, and a total construction area of 360,000m2, with concrete structure. Liu Jing Hotel was originally intended to be the world's tallest hotel with 3,000 rooms, and it is expected to open on 1989. The building works started on 1982, and the structural works stopped after the completion of 1992. At present, it is a concrete shell with no windows, no external wall formwork and no internal devices. Liu Jing Hotel has always been the most conspicuous landmark in Pyongyang since its flat roof, but it is not marked on the map of Pyongyang.
Liu Jing Hotel is a triangular pyramid building with an inclined angle of 75 degrees and a height of 330 meters, covering an area of 360,000 square meters. It is planned to have 3,000 rooms (note: North Korea's annual passenger flow is 2 100) and 7 revolving restaurants. If completed, it will be the tallest hotel in the world, the seventh tallest building, and the first building higher than100th floor in the world except new york and Chicago. Of course, it is also the tallest uncompleted residential flats in the world. Now, Liu Jing Hotel has resumed work, but the inferior cement structure may collapse at any time.
No.21Name: John Hancock Building, Chicago
The john hancock Building, nicknamed "Big John", is located in Chicago's so-called "Magnificent Mile" on North Michigan Avenue. Commercial buildings occupy the ground floor space and gradually become parking garages, office areas and residential areas. There is a viewing platform on the 94th floor, and a panoramic restaurant in Xiao Yun on the 95th and 96th floors. If a 45-story apartment building and a 70-story office building are built separately, the building will occupy most of the base, affecting privacy and lighting; A building with a floor of 100 was built first, and the saved base was used as an open space.
There are 7 1 1 apartments in the building, ranging from practical to 4-bedroom luxury apartments. There are also restaurants, health clubs, swimming pools and an ice rink; It's actually a small vertical city. At the top of this 1 127 feet (343.735 meters) high building are the transmission towers of several major television stations in Chicago. 50 elevators and 5 escalators get up and down every day 12000 guests. Because of its many functions, even after sunset, the activities in the "city" of John Hancock Building are still attractive.
In order to keep this 384 million pound behemoth 1 127 feet high, a huge caisson foundation reaching the bedrock was designed. One of them went into the ground 19 1 foot (58.225m).
The wedge-shaped tower has been reduced from 40,000 square feet (3716.1m2) at the bottom to18,000 square feet (1672.24m2) at the top. This modeling is not only conducive to the stability of the structure, but also conducive to the effective use of space. The eaves columns and truss beams form a steel bucket, which is reinforced by diagonal braces, which are clearly visible on the facade and the structural floors connected with these diagonal braces and corner columns. In this way, the structural system is very simple and the purpose is very effective. This creative structural system is also very economical, using only half of the steel used in the traditional internal column system (29.7 pounds per square foot of effective area, the latter is 40-50).
20th place: Kaohsiung Dongdi 185 International Plaza
Kaohsiung 85 Building, formerly known as Dongdi City Jiantai Building and Dongdi City 85 International Plaza (Tuntex &; Jiantai Building (or Tongtian Building) is a skyscraper located in Lingya District, Kaohsiung City, Taiwan Province Province, adjacent to Kaohsiung Port and Guangxin Wharf. The building is 378 meters high, with 85 floors above ground and 5 floors underground. Completed on 1997. Kaohsiung 85 Building is the tallest building in Kaohsiung. It was also the tallest building in Taiwan Province Province before the completion of Taipei 10 1. Once ranked among the top ten buildings in the world, it is now the second tallest building in Taiwan Province Province. Designed by architect Li Zuyuan.
It is located in the most prosperous and promising area in Kaohsiung, bordering Qiangzi Road in the east, Guangxin Road in the south and Sanduo Road in the north. It is only half a block away from Chenggong Road in the west, and it is a land, sea and air transportation hub. It can connect Xiaogang International Airport and Kaohsiung Railway Station from north to south, Fengshan and Pingtung in the east and Kaohsiung Port Area in the west. The traffic is very convenient.
No. 19: Beijing International Trade Phase III
The third phase of the International Trade Center, located in Beijing, China, was completed in 2007, with a height of 330m and a total of 74 floors. The third phase of the International Trade Center is jointly invested by the International Trade Center and the Guo Brothers Group, with a total investment of about 800 million US dollars. The main project was completed in 2008. By then, the third phase of International Trade will be not only the landmark building of Beijing Central Business District, but also the landmark building of Beijing in the future. Together with the first and second phases of the International Trade Center, a building complex of 165438+ 10,000 square meters will be formed, making it the largest international trade center in the world. At present, China World Hotel, Phase I International Trade Hotel and Phase II International Trade Office Building have become the representative buildings of Beijing CBD.
The total height of the main tower of International Trade Phase III is 330 meters, with 74 floors above ground and 4 floors underground. It integrates modern office buildings, luxury five-star hotels, high-grade banquet halls and boutique shopping malls. Construction started on June 16, 2005, which can resist an earthquake of magnitude 8. Every 15 floor is designed with an evacuation floor, so that people can take refuge nearby in an emergency, and helicopters can also be parked on the roof.
Because it is a super high-rise building, the third phase of ITC pays special attention to the comfort of use. The fresh air volume reaches per person per second 12 liter, which is higher than the American standard. There are 64 VAV devices on each floor of the office area, and the room temperature can be adjusted at will. There are also silencers at the end of air conditioning equipment and systems.
No. 18: China Minsheng Bank Building, Wuhan
Wuhan Minsheng Bank Building, located in Xinhua Road, Hankou, Wuhan, with a main height of 336 meters, is the tallest building in Central China, China. 68 floors above ground. The construction span is as long as ten years, and the middle is also recognized as an unfinished building, and the design scheme has been revised many times. The structure of Wuhan Minsheng Bank Building is rare in the world. The lower part is reinforced concrete and the upper part is full steel structure, which is controversial.
No. 17: Hong Kong Central Centre
The center is the fourth tallest building in Hong Kong and the 15 tallest building in the world, with a height of 346 meters and 73 floors above ground, second only to the International Finance Center, Central Plaza and Bank of China Building. It was completed in 1998, covering an area of100000 square feet, and providing commercial building area exceeding10.4000 square feet. Located in Queen's Road, Central and Western District, between the Central Station and the Central Station on the Hong Kong Island Line of the MTR. This is the Sheung Wan reconstruction project of the Land Development Corporation, which is developed by Changjiang Industry. The original site features streets such as Chinatown Street and Wentong Street, and the chemical industry is concentrated.
Sixteenth place: Aon Center, Chicago
Aon Center, located in Chicago, USA, is one of the headquarters of Aon Group. This is a skyscraper. When completed, it was the tallest building in Chicago and was replaced by Sears Tower the following year. The building is 346.3 meters high and has no antenna. The building is rectangular and covered with white granite. 1990 to 1992, large-scale construction of building external walls. The construction project is to replace the original 43,000 marble blocks with a two-inch thick granite block named "Mt.Airy", and the construction cost reaches 80 million US dollars. [ 1][2]
The original name of this building was Standard Oil Building. At that time, the owner of the building, Standard Oil Company, built this building to build a new headquarters building to replace the old headquarters building on South Michigan Avenue. The company was later renamed Amoco Petroleum 1985, and the building was renamed Amoco Building. 1998, Amoco Oil sold the building to Blackstone Group, and the building was renamed Aon Center on 1999 12.30. In May 2003, Fuguo Real Estate Investment Trust Company acquired Aon Center from Blackstone Group for $475 million.
No. 15: Dubai Emirates Tower
The Emirates Tower consists of two buildings with heights of 354.6 meters and 305 meters respectively, and a 9,000-square-meter shopping center connects the two buildings. The higher building serves as an office building, and the other is a six-star hotel. The usable area of the two buildings is about1.4000 square meters.
The two buildings are designed as mother-child towers, with roughly the same appearance and materials. The plane of the whole project is circular, and the location and layout of the two buildings consider sunlight, sunlight shadow, vision, airflow and religious ideas. Architectural design originates from the idea of Arab Islam, that is, taking the earth, the sun and the moon as design concepts and expressing them with simple structures such as triangles, cylinders and rectangles.
The UAE office building developed by real estate developer Sheikh Maktoum is part of the whole UAE building project. This building is one of the 20 tallest buildings in the world (as of 2005) and the tallest building in Dubai at present (as of 2006). Its actual height is 3 1 1 m, and the antenna is as high as 354.6 m.
The UAE office building and another building form a model of the mother-child tower. Architectural design originates from the idea of Arab Islam, that is, the earth, the sun and the moon are the design concepts. The exterior is triangular column, the structure is simple and lively, and the exterior wall is mainly made of glass curtain wall and white wall brick, creating a modern feeling. There is a hollow hall (lobby) in the lower part of the building, and the top rod is as high as 43.6 meters.
No. 14: Bank of China Building, Hong Kong
Bank of China Building in Hong Kong, designed by I.M. Pei Architects, completed on 1990. The total construction area is 6.5438+0.29 million square meters, with 70 floors above ground and a total height of 369 meters. The structure is supported by four-corner 12-story giant steel columns, and there is no column in the room. Until 1990, the Bank of China Tower was the tallest building outside the United States.
Careful observation of the Bank of China Building will reveal many common designs of Bayesian works. Take the plane as an example. Bank of China Tower is a square plane, diagonally divided into four groups of triangles, and the height of each group of triangles is different, which makes the facade varied in strict geometric specifications. As for the concept of plane, it can be traced back to the Madrid Tower in 1973. The Madrid Tower and the front of the square are also divided multilaterally. Is a series to analyze its combination.
No. 13: Central Plaza Building, Hong Kong
1993 the central plaza building in hong kong was completed, with a height of 374 meters and 78 floors, making it the tallest skyscraper in hong kong before. It is also one of the tallest buildings in the world. From 1992 to 1996 is the tallest building in Asia. Later, it was surpassed by Hong Kong's "International Financial Center Phase II".
The building looks like a triangle, but it is not a real triangle because its sharp corners have been cut off. There are two reasons: one is to have more convenient indoor area; More importantly, avoid offending neighbors by rushing to the sharp corner of their tax profits. Doing so is not only impolite, but more importantly, it will hinder "Feng Shui".
At the top of the building, the pyramid-shaped slope top and the mast standing on it are used as beams, which shine in the sun at night. The front is surrounded by three different colors of insulating glass. Gold-plated and silver-plated glass forms vertical and horizontal patterns, and patterned glass with different finishes is inserted between them, forming an elegant and sparkling image.
Twelfth place: Empire State Building, New York
The Empire State Building in new york is a masterpiece of decorative arts. Its height is 3,865,438+0 meters (65,438+0,250 feet) and it was completed in 65,438+0,936,5438+0 years. The Empire State Building has maintained the title of the tallest building in the world for 40 years. Later, it was surpassed by the World Trade Center in New York (collapsed in the 200 1 terrorist attack) and the Sears Tower, which ranked second in the United States.
The year when the Empire State Building was just built, the United States entered the Great Depression of the 1930s. The whole building can't find a customer who can afford to rent, so it can only earn money by looking at the building, and it has become a big empty can. King Kong was also created against the background of the Great Depression and the Empire State Building, and became a landmark of this historical classic film.
198 1 On April 30th, 2008, the Empire State Building with a height of 1250 feet and a floor of *** 102 in downtown new york, USA, spent 50 spring and autumn. In the 1930s, the American economy suffered a great depression, and people's lives became more difficult. However, Wall Street bosses are keen on the competition to build skyscrapers. Millionaire Rascobb decided to build the tallest building in the world to show his wealth. He called the famous architect william ram and asked how high the building could be built. Ram thought for a moment and then replied, "1050 feet." Rascobb was not satisfied with this height, because it was only 4 feet higher than the new Chrysler Building in new york. Therefore, the architect managed to add a 200-foot-high circular tower to make the height of the Empire State Building 1250 feet. This skyscraper was built in only 4 10 days, which is a miracle in the history of architecture. For a long time, the Empire State Building has been the tallest building in the world.
Eleventh place: Shenzhen Xinxing Plaza Building (Wang Di Building)
Shun Hing Plaza in Shenzhen is a 69-story skyscraper with a height of 384 meters (65,438+0,260 feet). "Xinxing Square" was the tallest building in China when 1996 was completed. A year later, it was surpassed by the "CITIC Plaza Building" in Guangzhou.
Wang Di Building in Xinxing Square consists of a 68-storey commercial building, a 32-storey commercial apartment, a 5-storey shopping center and a 2-storey underground parking lot. It is 384m high and covers an area of18734m 2, with a total construction area of 270,000 m2 and a total investment of HK$ 4 billion.
Tenth place: Guangzhou CITIC Plaza Building
Tianhe CITIC Plaza Building is the tallest building in Guangzhou in the 1990s after the 63rd floor Guangdong International Hotel, with a height of 39 1 m and 80 floors, which is still the highest in Guangdong Province. At the same time, it is also the tallest reinforced concrete building in the world.
As one of the tallest buildings in China, CITIC Plaza Building has 68 elevators. The person in charge of Poly Property said that the whole CITIC is a "street erected".
Although it is not the tallest building in China (surpassed by Jinmao Tower), it is the tallest concrete building in the world.
Ninth place: International Financial Center Building
Hong Kong Central International Finance Center Phase I 1998 completed, with 39 floors,180m. Since its establishment, it has attracted many international financial institutions. Guo Jin Phase II was completed in 2003, with a height of 420 meters and a total of 88 floors, making it the tallest building in Hong Kong. Known as the "masterpiece of the world", the design concept of the second phase of the international financial center expresses "welcome to you" to overseas friends with a gesture of "waving" to foreign friends.
Eighth place: Shanghai Jinmao Building
Jinmao Tower, a super-high-rise building with traditional style in China, is one of the landmark buildings in Shanghai towards the 2 1 century, which was designed by SOM design firm in the United States. 1998 completed in August. It covers an area of 23,600 square meters and has a building area of 289,500 square meters. It is 420.5 meters high and has 88 floors.
The main building of Jinmao Mansion 1 ~ 52 floors are office buildings, 53 ~ 87 floors are five-star hotels, and 88 floors are sightseeing. The building fully embodies the characteristics of the integration of traditional culture and modern high technology in China. It is not only the extension and development of the ancient tower architecture in China, but also the reappearance of Shanghai style architecture in Pudong.
Seventh place: New York World Trade Center Twin Towers (the tallest collapsed skyscraper)
In the early 1970s, Gemini was as high as 44 1 m, with a total floor of 1 10, making it the tallest building in new york and even in the world. 2001September 1 1 Sunday from 9: 00 am to 1 1 am, the personnel of Al-Qaida terrorist organization crashed and destroyed the South Tower and the North Tower, which became the most shocking terrorist incident in this century.
Gemini of New York World Trade Center was destroyed in the "911"terrorist attack, which killed nearly 4,000 people and turned new york Financial Center in the south of Manhattan into ruins. The World Trade Center in New York is the tallest skyscraper that collapsed and the tallest building except the Warsaw Radio Tower (643 meters).
Sixth place: Sears Tower, Chicago
Sears Tower is a skyscraper located in Chicago, Illinois, USA. It is 442 meters high, the total height of lightning rod is 527 meters, and the ground floor is 108. It was designed by architect Mies Vandler.
Chicago, Illinois, USA is the birthplace of skyscrapers. Built for Sears-Loubak Company, 1973 completed.
Sears Tower consists of nine towers. Their steel frames are welded together, which also helps to reduce the shaking in the wind caused by height. All towers have the same width, but different heights. The black belt outside the building cleverly covers the service facilities area.
Sears Tower has 1 10 floors and was once the tallest office building in the world. About 65438+6500 people come to work here every day. There is an observation deck on the 103 floor for tourists to overlook the whole city. 4 12 meters above the ground, you can see four States in the United States when the weather is clear.
Fifth place: Nanjing Zifeng Building
Zifeng Mansion, also known as Zifeng Mansion in Greenland Plaza, is a skyscraper under construction in Nanjing Greenland Plaza, capital of Jiangsu Province, China. The developers are Shanghai Greenland Group and Nanjing State-owned Assets Group. Zifeng Building, Nanjing Greenland Plaza is located in South Gulou Square, Gulou District, Nanjing, east to Central Road and west to Beijing West Road. There are historical sites such as Xuanwu Lake, Arctic Pavilion, Drum Tower and Ming City Wall around the Drum Tower. This area is the center of Nanjing urban area and the commanding height of the city. The surrounding prospects are panoramic: Zijinshan in the east, Yangtze River in the west, Yuhuatai in the south and Shogun Mountain in the north. It is also the gathering place of Nanjing University and Southeast University, famous universities in China. This section has convenient transportation, and important stations of subway 1 line are located in it. It is the intersection of Nanjing administrative axis and commercial axis. General situation of the building: the construction land area is 1872 1 m2. A 1 The total construction area of the plot is about 260,000 square meters. There are two towers (the main building and the auxiliary building) with one high and one low in the base, and the two towers are connected into a whole building group through a commercial podium. The main building has 89 floors above ground, with a total height of 450 meters and a roof height of 389 meters. It is the second tallest building in Chinese mainland (after Shanghai World Financial Center) and the seventh tallest building in the world (including under construction). The main functions are a six-star hotel (about 65,000 square meters) and a Grade A office building (about 55,000 square meters, with 24 floors above the ground and an effective height of 99.7 meters). Its main function is Grade A office building (about 2 1 1,000 square meters); The podium has 6 floors above ground and 7 floors locally, with an effective height of 37 meters above ground and 44 meters locally. Its main functions are shopping center (about 45,000 square meters) and rooms attached to the hotel. There are 4 floors underground, and the main functions are shopping malls, parking garages and equipment rooms (about 6 1000 square meters). The office height of the main building is 4.2m, the hotel height is 3.8m, the auxiliary building height is 4m, and the commercial floor height is 6m. The whole building has more than 50 vertical elevators and more than 30 escalators to ensure the flow of people and traffic and the quality of the whole building. The project started at the end of May 2005 and was put into use at the end of June 2009. The world's first super skyscraper-invested by China, built in China, future-oriented building and new direction sign of Nanjing-will rise in Nanjing, the ancient capital of the Six Dynasties.
Fourth place: The Petronas Petronas Petronas Petronas Twin Towers are located in gmcc Law in downtown Kuala Lumpur. It is 88 stories high and is a world-famous super building. Magnificence is the pride of Malaysia. It once broke the 22-year record of Sears Tower in Chicago, USA at a height of 45 1.9 meters. This project started on February 27th 1993, was officially capped on February 27th 1996, and was completed and put into use in June 5438+0997. When you climb the Twin Towers, you can see the beautiful scenery of Kuala Lumpur. The city lights are on at night, and the scenery is particularly magnificent.
The Petronas Twin Towers in Malaysia was designed by the famous architect Cesar Perry. /kloc-0 was the tallest building in the world when it was completed in 1998. Its design combines Islamic art style and is the deepest building in the world.
Third place: Shanghai World Financial Center
Shanghai World Financial Center project is a large-scale super-high-rise building, which is mainly for office work and integrates commercial, hotel, sightseeing, exhibition and other public facilities. Located in Lujiazui, Pudong, only 40 meters away from Jinmao Building. The total construction area of the project is 377,300 square meters, and the tower is above ground 1, 0 1 floor, with a ground height of 492 meters. It has the highest observation deck, five-star luxury hotel and retail space in the world. At the same time, Shanghai World Financial Center also surpassed Taipei Tower 10 1 in two of the four indicators of "World Tall Buildings", namely, "the height of the top floor without minarets" (487m) and "the height of the highest usable floor" (474m), and obtained the certificate issued by the World Tall Buildings Association, ranking first among skyscrapers. However, judging from the actual total height ranking, Shanghai World Financial Center is candidly admit defeat and ranks third in the world.
Second place: Taipei Taipei 10 1 building.
Known as the "New Landmark of Taipei", the Taipei 10 1 Building, 1998 65438+ 10 started construction in October, and the main project was completed in June 2003, with a height of 508 meters. There is the largest and heaviest "wind damper" in the world: an iron ball weighing 660 tons hangs from the roof inside the building. In order to keep balance when the typhoon comes, there are two elevators with the fastest speed in the world. It only takes 39 seconds to get from the first floor to the 89th floor. It holds the record of the fastest elevator in the world (60.4 kilometers per hour). In terms of actual height, the total height of Taipei 10 1 does not reach 487 meters of Shanghai World Financial Center, but it ranks second in the world with a total height of 508 meters.
First place: Burj Khalifa, Dubai
Burj Khalifa (Arabic:? Burj Khalifa) Formerly known as Burj Khalifa (Arabic: Burj Khalifa)
[Burj Khalifa 828 meters]
Burj Khalifa is 828 meters.
Dubai), also known as Burj Dubai or Burj Dubai, is a completed skyscraper located in Dubai, United Arab Emirates, with a total height of 828 meters, which is 320 meters higher than that of Taipei 10 1. Burj Dubai was built by South Korea's Samsung Company. Construction started on September 2, 2004, and was completed and put into use on September 4, 2065. It was officially renamed Burj Dubai.