Tuesday, September 09, 2008

Human population density

For humans, population density is the number of people per unit of area (which may include or exclude cultivated or potentially productive area). Commonly this may be calculated for a county, city, country, another territory, or the entire world.

The world population is 6.6 billion, and Earth's area is 510 million square kilometers (200 million square miles). Therefore the world-wide human population density is 6.6 billion / 510 million = 13 per km² (33 per sq mi), or 43 per km² (112 per sq mi) if only the Earth's land area of 150 million km² (58 million sq mi) is taken into account. This density rises when the population grows. It also includes all continental and island land area, including Antarctica. Considering that over half of the earth's land mass consists of areas inhospitable to human inhabitation, such as deserts and high mountains, and that population tends to cluster around seaports and fresh water sources, this number by itself does not give the most accurate measurement of human population density.

Several of the most densely-populated territories in the world are city-states, microstates, micronations, or dependencies. These territories share a relatively small area and a high urbanization level, with an economically specialized city population drawing also on rural resources outside the area, illustrating the difference between high population density and overpopulation.

Cities with high population densities are, by some, considered to be overpopulated, though the extent to which this is the case depends on factors like quality of housing and infrastructure or access to resources. Most of the most densely-populated cities are in southern and eastern Asia, though Cairo and Lagos in Africa also fall into this category.

City population is however, heavily dependent on the definition of "urban area" used: densities are typically higher for the central municipality itself, than when more recently-developed and administratively unincorporated suburban communities are included, as in the concepts of agglomeration or metropolitan area, the latter including sometimes neighbouring cities.

Thursday, September 04, 2008

DoDAF

The Department of Defense Architecture Framework (DoDAF) defines a standard way to organize an enterprise architecture (EA) or systems architecture into complementary and consistent views. All major U.S. Government Department of Defense (DoD) weapons and information technology system procurements are required to develop and document an EA using the views prescribed in the DoDAF. While it is clearly aimed at military systems, DoDAF has broad applicability across the private, public and voluntary sectors around the world, and represents only one of a large number of systems architecture frameworks.It is especially suited to large systems with complex integration and interoperability challenges, and is apparently unique in its use of "operational views" detailing the external customer's operating domain in which the developing system will operate