Geothermal gradient

Geothermal gradient is the rate of increasing temperature with respect to increasing depth in the Earth's interior. Away from tectonic plate boundaries, it is about 25 °C per km of depth (1 °F per 70 feet of depth) near the surface in most of the world. Strictly speaking, geo-thermal necessarily refers to the Earth but the concept may be applied to other planets. A line tracing the gradient through the planetary body is called a geotherm on Earth and other terrestrial planets. On the Moon it is called a selenotherm.

The Earth's internal heat comes from a combination of residual heat from planetary accretion, heat produced through radioactive decay, and possibly heat from other sources. The major heat-producing isotopes in the Earth are potassium-40, uranium-238, uranium-235, and thorium-232. At the center of the planet, the temperature may be up to 7,000 K and the pressure could reach 360 GPa(3.6 million atm). Because much of the heat is provided by radioactive decay, scientists believe that early in Earth history, before isotopes with short half-lives had been depleted, Earth's heat production would have been much higher. Heat production was twice that of present-day at approximately 3 billion years ago, resulting in larger temperature gradients within the Earth, larger rates of mantle convection and plate tectonics, allowing the production of igneous rocks such as komatiites that are not formed anymore today.

Geothermal (disambiguation)

Geothermal is related to energy and may refer to:

Renewable technology

Project

In contemporary business and science a project is a collaborative enterprise, involving research or design, that is carefully planned to achieve a particular aim.

Project can also be defined as a set of interrelated tasks to be executed over a fixed period and within certain cost and other limitations.

Projects can be further defined as temporary rather than permanent social systems or work systems that are constituted by teams within or across organizations to accomplish particular tasks under time constraints. An ongoing project is usually called (or evolves into) a program.

Overview

The word project comes the Latin word projectum from the Latin verb proicere, "before an action" which in turn comes from pro-, which denotes precedence, something that comes before something else in time (paralleling the Greek πρό) and iacere, "to do". The word "project" thus actually originally meant "before an action".

When the English language initially adopted the word, it referred to a plan of something, not to the act of actually carrying this plan out. Something performed in accordance with a project became known as an "object".Every project has certain phases of development.

Public housing

Public housing may be a form of housing tenure in which the property is owned by a government authority, which may be central or local. Social housing is an umbrella term referring to rental housing which may be owned and managed by the state, by non-profit organizations, or by a combination of the two, usually with the aim of providing affordable housing. Social housing can also be seen as a potential remedy to housing inequality. Some social housing organizations construct for purchase, particularly in Spain and to an extent elsewhere.

Although the common goal of public housing is to provide affordable housing, the details, terminology, definitions of poverty and other criteria for allocation vary within different contexts.

History

The origins of municipal housing lie in the dramatic urban population increase caused by the Industrial Revolution of the 19th century. In the large cities of the period, many social commentators, such as Octavia Hill and Charles Booth reported on the squalor, sickness and immorality that arose. Henry Mayhew, visiting Bethnal Green, wrote in the The Morning Chronicle: