Drawing exchange format

In order for CAD applications to run across systems from various vendors, four main formats facilitate this data exchange IGES (Initial Graphics Exchange Specification), STEP (Standard for the Exchange of Product Model Data), DXF (Drawing Exchange Format), and ACIS (American Committee for Inter-operable Systems)... 

The layout editor may have an internal data format that is used to store the layout, and it should also be able to generate output data files in the formats that are commonly used by foundries. These include GIF (Caltech Intermediate Format) and GDSII (Graphic Data System). Some tools do not support these formats, but it may be possible to find eon-verters from one file format, such as DXF (Drawing Exchange Format), to the required format, such as GDSII. Typically the user will transfer the data file to the foundries mask data folder using an FTP (file transfer protocol) command. In some cases the foundry may require the user to submit checksum data to ensure that the file transferred eorrectly. 

New boilers, heat exchangers, and other equipment must be provided with a PCC program to remove oil, grease, mill scale, pipe-threading compounds, drawing compounds, and other detritus that otherwise prevent the formation of clean, passivated metal surfaces and encourage... 

The discussion relating to the metabolism of bacteria in biofilms is of necessity short. Nevertheless it does draw attention to the complexity of bacterial biofilm formation and development, commonly encountered in heat exchangers associated with aqueous industrial systems such as cooling water. It is on account of these... 

The reductive elimination of arenes from aryl hydride complexes draws many parallels with the reductive elimination from alkyl hydrides. For example, arene complexes are believed to form from ttie reductive elimination prior to release of the free arene. Studies by Feher and Jones provided compelling evidence for the presence of arene complexes, - and complementary synthetic studies have led to the isolation of closely related "q -arene complexes. " As shown in Equation 8.24, the arylrhodium deuteride complex scrambles deuterium into the aryl ring, just as alkyhnetal deuteride complexes scramble deuterium into the alkyl group. This isotopic exchange presumably occurs by formation of the arene complex shown at the center of Equation 8.24... 

In the 80s a large number of different CAD systems were developed. This made the necessity for standards for data exchange obvious. At the beginning, dedicated standards for drawings and 3D models appeared. In 1984 the development of STEP started as a successor of formats such as IGES, SET and VDA-ES (Eig. 21.13). The initial plan was to develop one implementation independent product data model for all purposes. Because of the complexity the standard was modularized. In 1995 ISO published the first initial release. Based on these modules different user communities could create application protocols that adapt the data model and definitions to the specific requirements of the business. Eor automotive AP 214 was defined and enhanced continuously [23]. 

DXF, developed by Autodesk, Inc. for AutoCAD software, is the de facto standard for exchanging CAD/CAM data on a PC-based system. Only 2-D drawing information can be converted into DXF, either in ASCII or in binary format. 

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