Question

explain utilize the Data Dictionary by implementing in Satellite Antenna Modeling

Answer 1

INTRODUCTION

In Data Exchange Language The Data Dictionaries , providing the data model, are the key elements.The dictionaries define exactly and in detail all the elements that will appear in a specific data set that complies with them, including all physical and mathematical items and quantities. For each one of the latter they include a name, a precise definition, measurement units, data types, data structures, etc.Each Data Dictionary defines the meaning of the data and the conventions used to define a specific physical entity, e.g. electromagnetic field or structure geometry.

A common reference for the exchange of geometry and accessory data for EM modelling is a longstanding desire among users of analysis and design tools. For this reason the Structure Data Dictionary has been proposed; it directly address the need for standardization in layer is defined as a separate folder. Furthermore, multiple Data Dictionaries could be defined in the same EDI file.

References can be made to data elements among folders, which can also be associated to different Data Dictionaries. The same basic structure applies also when data are (partially) stored in HTF5 repositories to save space and seed-up data transfer. An archive is used in this case to collect all elements into a single file.

The edi.xsd schema allows checking the validity of structure and vocabulary of an EDI file against the grammatical rules of the appropriate XML language. The Declaration Section is organized in folders and for each folder is defined the reference Data Dictionary

The meaning of attributes of class Convention should be obvious i.e the Reference System Type is Cartesian and the used Length Units is meter.

The language also offers the possibility to specify data consistency and integrity rules. In the Class Settings, the Spatial Resolution is defined as a positive number and the unit is the one defined in Length Units.

  DATA DICTIONARY LANGUAGE(DDL)

The Data Declaration Language (DDL) is a supporting element devised to help in the definition and use of Data Dictionaries.

It allows the formal and computer-readable definition of the rules that data in an EDI file must obey to conform to a given Data Dictionary

The DDL can also be used for the formulation of dictionaries for proprietary data. This will enable programs in general to utilize the powerful features of the EDX.

Structure Data Dictionary

The Structure Data Dictionary allows the complete and organized definition of all physical details of an electromagnetic model.To achieve a good level of completeness and generality there is a need of multiple description of the same objects . The description must also relieve the human reader from inspecting long lists of raw geometrical data to understand the content. A highly structured data model with layered structure has been chosen to this end.

The Structure Data Dictionary is organized in folders; the folder General defines the general conventions of the Structure folder. The class Conventions and Settings are defined as a single instance, they are valid for all Structure Data Dictionary

folder Structares folder General clasa Conventions attribute Referencesystemtype cartesian attribute PositivevectorProductRightand attribute SurfaceBoundaryorientation Counterclockwise attribute VoluneBoundaryorientation: Outward attribate Lengthnita: aizes 1 rules instantiation zingleinstance class Settings sizes 1 component resolution type float end rules instantiation inaleinstance integrity relationresolution>0 end end end endtolder General end Structures end idictionary

EMERALD SATELLITE EXAMPLE

A prototype software tool (based on the open source libraries PythonOCC and Salome Geometry Module) has been developed for CAD conditioning operations and extension with electromagnetic data, also handling parameterized geometries. The tool is using EDX as data exchange layer. The Structure Data Dictionary has been used and improved for the purpose.

The tool allows to manage a mechanical CAD file of a complex structure (such as a satellite) in order to make it suitable to EM analysis. The workflow is the following:

• a mechanical CAD file is imported
• the file is cleaned
• extra information can be added: materials, ports and parameters
• the conditioned file is exported

   CONCLUSION

The exchange of geometrical data across the antenna design process is a key issue for which a generally accepted and stable solution is missing. The Structure Data Dictionary directly addresses the need for standardization in mesh exchange trying to provide a comprehensive and robust solution.