Liquefied natural gas

Liquefied natural gas (LNG) is natural gas (predominantly methane, CH₄) that has been converted to liquid form for ease of storage or transport. It takes up about 1/600th the volume of natural gas in the gaseous state. It is odorless, colorless, non-toxic and non-corrosive. Hazards include flammability after vaporization into a gaseous state, freezing and asphyxia. The liquefaction process involves removal of certain components, such as dust, acid gases, helium, water, and heavy hydrocarbons, which could cause difficulty downstream. The natural gas is then condensed into a liquid at close to atmospheric pressure by cooling it to approximately −162 °C (−260 °F); maximum transport pressure is set at around 25 kPa (4 psi).

LNG achieves a higher reduction in volume than compressed natural gas (CNG) so that the (volumetric) energy density of LNG is 2.4 times greater than that of CNG or 60 percent that of diesel fuel. This makes LNG cost efficient to transport over long distances where pipelines do not exist. Specially designed cryogenic sea vessels (LNG carriers) or cryogenic road tankers are used for its transport. LNG is principally used for transporting natural gas to markets, where it is regasified and distributed as pipeline natural gas. It can be used in natural gas vehicles, although it is more common to design vehicles to use compressed natural gas. Its relatively high cost of production and the need to store it in expensive cryogenic tanks have hindered widespread commercial use. Despite these drawbacks, on energy basis LNG production is expected to hit 10% of the global crude production by 2020.(see LNG Trade)

Pyramid

A pyramid (from Greek: πυραμίς pyramis) is a structure whose outer surfaces are triangular and converge to a single point at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilateral, or any polygon shape, meaning that a pyramid has at least three outer triangular surfaces (at least four faces including the base). The square pyramid, with square base and four triangular outer surfaces, is a common version.

A pyramid's design, with the majority of the weight closer to the ground, and with the pyramidion on top means that less material higher up on the pyramid will be pushing down from above. This distribution of weight allowed early civilizations to create stable monumental structures. More recently, it was shown that the common shape of the pyramids of antiquity, from Egypt to Central America, represents the dry-stone construction that requires minimum human work.

Egyptian pyramids

The Egyptian pyramids are ancient pyramid-shaped masonry structures located in Egypt.

As of November 2008, there are sources citing both 118 and 138 as the number of identified Egyptian pyramids. Most were built as tombs for the country's pharaohs and their consorts during the Old and Middle Kingdom periods.

The earliest known Egyptian pyramids are found at Saqqara, northwest of Memphis. The earliest among these is the Pyramid of Djoser (constructed 2630 BC–2611 BC) which was built during the third dynasty. This pyramid and its surrounding complex were designed by the architect Imhotep, and are generally considered to be the world's oldest monumental structures constructed of dressed masonry.

The most famous Egyptian pyramids are those found at Giza, on the outskirts of Cairo. Several of the Giza pyramids are counted among the largest structures ever built. The Pyramid of Khufu at Giza is the largest Egyptian pyramid. It is the only one of the Seven Wonders of the Ancient World still in existence.

Pyramids (novel)

Pyramids is the BSFA winning seventh Discworld novel by Terry Pratchett, published in 1989.

Plot summary

The main character of Pyramids is Teppic, prince of the tiny kingdom of Djelibeybi. Djelibeybi is the Discworld counterpart to Ancient Egypt.

Young Teppic has been in training at the Assassins Guild in Ankh-Morpork for several years. The day after passing his final exam he mystically senses that his father has died and that he must return home. Being the first Djelibeybian king raised outside the kingdom leads to some interesting problems, based on the fact that Dios, the high priest, is a stickler for tradition, and does not, in fact, allow the pharaohs to rule the country.

After numerous adventures and misunderstandings, Teppic is forced to escape from the palace, along with a handmaiden named Ptraci. Meanwhile, the massive pyramid being built for Teppic's father warps space-time so much that it "rotates" Djelebeybi out of alignment with the space/time of the rest of the disc by 90 degrees. Teppic and Ptraci travel to Ephebe to consult with the philosophers there as to how to get back inside the Kingdom. Meanwhile, pandemonium takes hold in Djelibeybi, as the kingdom's multifarious gods descend upon the populace, and all of Djelibeybi's dead rulers come back to life.