Monday, April 28, 2008

Piri Reis map

The Piri Reis map ("Piri" pronounced /piɹi/) is a famous pre-modern world map created by 16th century Ottoman-Turkish admiral and cartographer Piri Reis. The map shows part of the western coasts of Europe and North Africa with reasonable accuracy, and the coast of Brazil is also easily recognizable. Various Atlantic islands including the Azores and Canary Islands are depicted, as is the mythical island of Antillia. The map is noteworthy for its depiction of a southern landmass that some controversially claim is evidence for early awareness of the existence of Antarctica.

Monday, April 21, 2008

Marine Cargo Types

There is a wide range of marine cargoes at seaport terminals operated. The primary types are these:

* Containers are the largest and fastest growing cargo category at most ports worldwide. Containerized cargo includes everything from auto parts and machinery components to shoes, toys, and frozen meat and seafood.

* Automobiles are handled at many ports.

* Project cargo and heavy lift cargo may include items such as manufacturing equipment, factory components, power equipment such as generators and wind turbines, military equipment or almost any other oversized or overweight cargo too big or too heavy to fit into a container.

* Break bulk cargo is typically material stacked on wooden pallets and lifted into and out of the hold of a vessel by cranes on the dock or aboard the ship itself. The volume of break bulk cargo has declined dramatically worldwide as containerization has grown.

* Bulk Cargoes, such as salt, oil, tallow, and Scrap metal, are usually defined as commodities that are neither on pallets nor in containers, and which are not handled as individual pieces, the way heavy-lift and project cargoes are. Alumina, grain, gypsum, logs and wood chips, for instance, are bulk cargoes.

Monday, April 14, 2008

Logical schema

A Logical Schema is a data model of a specific problem domain that is in terms of a particular data management technology. Without being specific to a particular database management product, it is in terms of either (for example, in 2007) relational tables and columns, object-oriented classes, or XML tags. This is as opposed to a conceptual data model, which describes the semantics of an organization without reference to technology, or a physical data model, which describes the particular physical mechanisms used to capture data in a storage medium.

Monday, April 07, 2008

Apache Derby

Apache Derby relational database management system that can be embedded in Java programs and used for online transaction processing. It has a 2 MB disk-space footprint. Apache Derby is developed as an open source project under the Apache 2.0 licence. Derby was previously distributed as IBM Cloudscape and Sun Java DB.

Friday, April 04, 2008

Relational model

The relational model for database management is a database model based on predicate logic and set theory. It was first formulated and proposed in 1969 by Edgar Codd with aims that included avoiding, without loss of completeness, the need to write computer programs to express database queries and enforce database integrity constraints. "Relation" is a mathematical term for "table", and thus "relational" roughly means "based on tables". It did not originally refer to the links or "keys" between tables, contrary to popular interpretation of the name.