Twin cities

Twin cities are a special case of two cities or urban centres that are founded in close geographic proximity and then grow into each other over time, losing most of their mutual buffer zone. In the United States, "the Twin Cities" usually refers to the Minneapolis-Saint Paul metropolitan area in Minnesota.

There are no precise criteria for twin-cityhood, but to be considered twin cities, the cities involved have to have a similar administrative status and somewhat comparable sizes; a suburb of a much larger population center is usually not considered to form a twin city with it. For example, South San Francisco (population about 65,000) is not considered a twin city with San Francisco (population about 850,000). However, cities considered twinned by proximity do not necessarily match demographically, economically, or politically.

In many historical cases, cities that grew into each other's space lost their individual identities, and the border or barrier originally separating them became almost irrelevant. An 1873 case of twin cities merging to become a united city is Budapest in Hungary, which began as two settlements (Buda and Pest) facing each other across the Danube at a strategic fording place along a trade route. In China, the three ancient cities of Hankou, Hanyang, and Wuchang, separated by the junction of the Yangtze and Hanjiang rivers, were joined in 1927 into the single entity of Wuhan.

Minneapolis–Saint Paul

Minneapolis–Saint Paul is a major metropolitan area built around the Mississippi, Minnesota and St. Croix rivers. The area is commonly known as the Twin Cities for its two largest cities, Minneapolis the city with the highest population in Minnesota and Saint Paul, the state capital. It is a classic example of twin cities in the sense of geographical proximity. Together the two cities anchor the second-largest economic center in the Midwest, behind Chicago.

There are several different definitions of the region. Many refer to the Twin Cities as the seven-county region which is governed under the Metropolitan Council regional governmental agency and planning organization. The United States Office of Management and Budget officially designates 16 counties as the Minneapolis-St. Paul–Bloomington MN-WI Metropolitan Statistical Area, the 16th largest in the United States. The entire region known as the Minneapolis-St. Paul MN-WI Combined Statistical Area, has a population of 3,797,883, the 14th largest, according to 2013 Census estimates.

Zephyr

Zephyr may refer to:

People

Computing

Transport

Aviation

Zephyr (garment)

A zephyr is a garment worn in competitive rowing.

A zephyr is usually a short-sleeved T-shirt with a front opening, with the opening and sleeve ends trimmed in the colours of the club.

Zephyr, as a garment, appears in the 1927 novel Blind Corner by Dornford Yates. "... I followed immediately, clad only in a zephyr and shorts, and was in the boat almost a soon as he."

Qinetiq Zephyr

The Qinetiq Zephyr is a series of lightweight solar-powered UAV originally designed and built by the United Kingdom company, QinetiQ, and is now part of the Airbus High Altitude Pseudo-Satellite (HAPS) programme.

Development

The Zephyr 7 holds the official endurance record for an unrefuelled, unmanned aerial vehicle with its flight from 9 July to 23 July 2010, lasting 336 hours, 22 minutes and 8 seconds. It could also remain airborne for months thanks to its solar batteries. Record claims have been verified by the Fédération Aéronautique Internationale (FAI) for both duration and altitude, at 21,562 meters. It more than doubled the previous endurance record for unmanned flight.

In a 2008 demonstration for the US military, a smaller-scale version of the Zephyr (Zephyr 6) performed beyond the official world record for the longest-duration unmanned flight, however its 82-hour flight at an altitude of 61,000 ft (19,000 m) did not set an official record because FAI officials were not involved in the flight.