搜尋結果
Wikipedia [c] is a free content online encyclopedia written and maintained by a community of volunteers, known as Wikipedians, through open collaboration and the wiki software MediaWiki.Wikipedia is the largest and most-read reference work in history, [3] [4] and is consistently ranked among the ten most visited websites; as of August 2024, it was ranked fourth by Semrush, [5] and seventh by ...
China,[i] officially the People's Republic of China (PRC),[j] is a country in East Asia. With a population exceeding 1.4 billion, it is the world's second-most populous country after India, representing 17.4% of the world population. China spans the equivalent of five time zones and borders fourteen countries by land.[k] With an area of nearly ...
PPP largely removes the exchange rate problem but not others; it does not reflect the value of economic output in international trade, and it also requires more estimation than GDP per capita. On the whole, PPP per capita figures are more narrowly spread than nominal GDP per capita figures.
On January 6, 2021, the United States Capitol Building in Washington, D.C., was attacked by a mob[39][40][41] of supporters of then–U.S. President Donald Trump in an attempted self-coup d'état[42] two months after his defeat in the 2020 presidential election. They sought to keep Trump in power by occupying the Capitol and preventing a joint ...
- Background
- The Two Crashes
- Collapse of The Towers
- Building 7 Collapse
- Other Buildings
- Investigations
- Aftermath
- External Links
When they opened in 1973, the Twin Towers were the tallest buildings in the world. At the time of the attacks only the Petronas Towers in Kuala Lumpur, Malaysia and the Willis Tower (known then as the Sears Tower) in Chicago were taller. Built with a novel "framed tube" design that maximized interior space, the towers had a high strength-to-weight ...
Aircraft impacts and resultant fires
During the September 11 attacks, four teams of al-Qaeda terrorists hijacked four different jetliners. Two of these jetliners, American Airlines Flight 11 and United Airlines Flight 175, both Boeing 767s, were hijacked after takeoff from Boston's Logan International Airport. In its final moments, American Airlines Flight 11 flew south over Manhattan and crashed at roughly 440 mph (710 km/h) into the northern facade of the North Tower (WTC 1) at 8:46 a.m., hitting the 93rd through 99th floors....
Emergency response and evacuation
Almost all the deaths in the Twin Towers occurred in the zones above the points of aircraft impact. As the North Tower had been struck almost directly midway into the structure, the three main stairways (A, B, and C) in the tower core were all damaged or blocked by debris preventing escape to lower floors. In the South Tower, the impact was east of center to the central section of the tower and close to the southeast corner, resulting in stairway A in the northwest portion of the central core...
The destruction of the Twin Towers has been called "the most infamous paradigm" of progressive collapse. Each collapse began with the local failure of the vertical load-bearing components of the floors that were hit by the planes and progressed to encompass the whole of the structure. Structural components were severed, releasing gravitational ener...
As the North Tower collapsed, heavy debris hit 7 World Trade Center, causing damage to the south face of the building and starting fires that continued to burn throughout the afternoon. Structural damage occurred to the southwest corner between Floors 7 and 17 and on the south facade between Floor 44 and the roof; other possible structural damage i...
Many of the surrounding buildings were also either damaged or destroyed as the towers fell. 5 WTC endured a large fire and a partial collapse of its steel structure and was torn down. Other buildings destroyed include St. Nicholas Greek Orthodox Church, Marriott World Trade Center (Marriott Hotel 3 WTC), South Plaza (4 WTC), and U.S. Customs (6 WTC...
Initial opinions and analysis
In the immediate aftermath of the attacks, numerous structural engineers and experts spoke to the media, describing what they thought caused the towers to collapse. Abolhassan Astaneh-Asl, a structural engineering professor at the University of California at Berkeley, explained that the high temperatures in the fires weakened the steel beams and columns, causing them to become "soft and mushy", and eventually they were unable to support the structure above. Astaneh-Asl also suggested that the...
FEMA building performance study
FEMA suggested that fires in conjunction with damage resulting from the aircraft impacts were the key to the collapse of the towers. Thomas Eagar, Professor of Materials Engineering and Engineering Systems at MIT, described the fires as "the most misunderstood part of the WTC collapse". This is because the fires were originally said to have "melted" the floors and columns. Jet fuel is essentially kerosene and would have served mainly to ignite very large, but not unusually hot, hydrocarbon fi...
NIST report
After the FEMA report had been published, and following pressure from technical experts, industry leaders and families of victims, the Commerce Department's National Institute of Standards and Technology conducted a three-year, $16 million investigation into the structural failure and progressive collapse of several WTC complex structures. The study included in-house technical expertise, along with assistance from several outside private institutions, including the Structural Engineering Inst...
Cleanup
The cleanup was a massive operation coordinated by the City of New York Department of Design and Construction. On September 22, a preliminary cleanup plan was delivered by Controlled Demolition, Inc. (CDI) of Phoenix, Maryland. Costing hundreds of millions of dollars, it involved round-the-clock operations with many contractors and subcontractors. By early November, with a third of the debris removed, officials began to reduce the number of firefighters and police officers assigned to recover...
Health effects
The collapse of the World Trade Center produced enormous clouds of dust that covered Manhattan for days. On September 18, 2001, the United States Environmental Protection Agency (EPA) assured the public that the air in Manhattan was "safe to breathe". In 2003 the EPA's inspector general found that the agency did not at that time have sufficient data to make such a statement. Dust from the collapse seriously reduced air quality and is likely the cause of many respiratory illnesses in lower Man...
World Trade Center – Some Engineering Aspects Archived March 6, 2012, at the Wayback MachineEarly suggestion by University of Sydney engineering instructor about how the towers might have collapsed.Genghis Khan[a] (born Temüjin; c. 1162 – August 1227), also known as Chinggis Khan, [b] was the founder and first khan of the Mongol Empire. After spending most of his life uniting the Mongol tribes, he launched a series of military campaigns, conquering large parts of China and Central Asia.
Adolf Hitler[a] (20 April 1889 – 30 April 1945) was an Austrian-born German politician who was the dictator of Nazi Germany from 1933 until his suicide in 1945. He rose to power as the leader of the Nazi Party, [c] becoming the chancellor in 1933 and then taking the title of Führer und Reichskanzler in 1934.
國安基金不退場 相關
廣告以選股關鍵指標ROE成長率評估成長性，權重調整再強化，搭上ESG趨勢順風讓投資更輕鬆。 以股利率獲取為核心，完善高股息的三大關鍵-鞏固填息力、強化成長動能、把握趨勢主題。
