Wikipedia articles of interest

1. Star fort.

“A star fort, or trace italienne, is a fortification in the style that evolved during the age of gunpowder, when the cannon came to dominate the battlefield, and was first seen in the mid-15th century in Italy.

Passive ring-shaped (enceinte) fortifications of the Medieval era proved vulnerable to damage or destruction by cannon fire, when it could be directed from outside against a perpendicular masonry wall. In addition, an attacking force that could get close to the wall was able to conduct undermining operations in relative safety, as the defenders could not shoot at them from nearby walls. In contrast, the star fortress was a very flat structure composed of many triangular bastions, specifically designed to cover each other, and a ditch. In order to counteract the cannon balls, defensive walls were made lower and thicker. Although this made their climbing easier, the ditch was widened, so that attacking infantry was still exposed to fire from a higher elevation for a while, including enfilading fire from the bastions. The outer side of the ditch was usually provided with a glacis to deflect cannon balls aimed at the lower part of the main wall. Further structures, such as ravelins, tenailles, hornworks or crownworks, and even detached forts could be added to create complex outer works to further protect the main wall from artillery, and sometimes provide additional defensive positions. They were built of many materials, usually earth and brick, as brick does not shatter on impact from a cannonball as stone does.

Star fortifications were further developed in the late fifteenth and early sixteenth centuries primarily in response to the French invasion of the Italian peninsula. The French army was equipped with new cannon and bombards that were easily able to destroy traditional fortifications built in the Middle Ages. Star forts were employed by Michelangelo in the defensive earthworks of Florence, and refined in the sixteenth century by Baldassare Peruzzi and Scamozzi. The design spread out of Italy in the 1530s and 1540s. It was employed heavily throughout Europe for the following three centuries. […]

Fortifications of this type continued to be effective while the attackers were armed only with cannons, where the majority of the damage inflicted was caused by momentum from the impact of solid shot. While only low explosives such as black powder were available, explosive shells were largely ineffective against such fortifications.

The development of mortars, high explosives, and the consequent large increase in the destructive power of explosive shells and thus plunging fire rendered the intricate geometry of such fortifications irrelevant. Warfare was to become more mobile. It took, however, many years to abandon the old fortress thinking.”

2. Byzantine Empire (featured). This seems to be one of the topics that Wikipedia covers very well – there’s a lot of stuff here, and lots of links both to other articles and to external sources.

3. Lyapunov stability.

4. Tornado (featured).

From the article:

“The United States averages about 1,200 tornadoes per year. The Netherlands has the highest average number of recorded tornadoes per area of any country (more than 20, or 0.0013 per sq mi (0.00048 per km2), annually), followed by the UK (around 33, or 0.00035 per sq mi (0.00013 per km2), per year),[64][65] but most are small and cause minor damage. In absolute number of events, ignoring area, the UK experiences more tornadoes than any other European country, excluding waterspouts.[61]

Tornadoes kill an average of 179 people per year in Bangladesh, the most in the world. This is due to high population density, poor quality of construction and lack of tornado safety knowledge, as well as other factors.[66][67] Other areas of the world that have frequent tornadoes include South Africa, parts of Argentina, Paraguay, and southern Brazil, as well as portions of Europe, Australia and New Zealand, and far eastern Asia.[7][68]

5. Formal system (logic).

6. Ferdinand I, Holy Roman Emperor.

Ferdinand I (10 March 1503, Alcalá de Henares, Spain – 25 July 1564, Vienna, Habsburg domain [now in Austria]) was Holy Roman Emperor from 1558, king of Bohemia and Hungary from 1526, and king of Croatia from 1527 until his death.[1][2] Before his accession, he ruled the Austrian hereditary lands of the Habsburgs in the name of his elder brother, Charles V, Holy Roman Emperor.

The key events during his reign were the contest with the Ottoman Empire, whose great advance into Central Europe began in the 1520s, and the Protestant Reformation, which resulted in several wars of religion.

Ferdinand’s motto was Fiat iustitia, et pereat mundus: “Let justice be done, though the world perish”.

7. Wheat.

Wheat (Triticum spp.)[1] is a cereal grain, originally from the Levant region of the Near East and Ethiopian Highlands, but now cultivated worldwide. In 2010 world production of wheat was 651 million tons, making it the third most-produced cereal after maize (844 million tons) and rice (672 million tons).[2] In 2009, world production of wheat was 682 million tons, making it the second most-produced cereal after maize (817 million tons), and with rice as close third (679 million tons).[3]

This grain is grown on more land area than any other commercial crop and is the most important staple food for humans. World trade in wheat is greater than for all other crops combined.[4] Globally, wheat is the leading source of vegetable protein in human food, having a higher protein content than either maize (corn) or rice, the other major cereals. […]

“Unlike rice, wheat production is more widespread globally though China’s share is almost one-sixth of the world.” [roughly corresponding to the Chinese share of the global population. I was also surprised to learn that China in 2010 produced almost twice as much wheat (115 million metric tons) as the United States (60 -ll-) did.] […]

“In the 20th century, global wheat output expanded by about 5-fold, but until about 1955 most of this reflected increases in wheat crop area, with lesser (about 20%) increases in crop yields per unit area. After 1955 however, there was a dramatic ten-fold increase in the rate of wheat yield improvement per year, and this became the major factor allowing global wheat production to increase. Thus technological innovation and scientific crop management with synthetic nitrogen fertilizer, irrigation and wheat breeding were the main drivers of wheat output growth in the second half of the century. There were some significant decreases in wheat crop area, for instance in North America.[60]

Better seed storage and germination ability (and hence a smaller requirement to retain harvested crop for next year’s seed) is another 20th century technological innovation. In Medieval England, farmers saved one-quarter of their wheat harvest as seed for the next crop, leaving only three-quarters for food and feed consumption. By 1999, the global average seed use of wheat was about 6% of output.”

August 26, 2012 - Posted by | biology, Geography, history, mathematics, wikipedia

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