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COMPUTATIONAL METHODS IN ENGINEERING AND SCIENCE
EPMESC X, Aug. 21-23, 2006, Sanya, Hainan, China
©2006 Tsinghua University Press & Springer
Development of a Knowledge Based System for the Portuguese Code
for Building Acoustics
João Mariz Graça 1*, Jorge Patrício 2, Luís Santos Lopes 3
1
Lusíada University, Lisboa, Portugal
LNEC, Av. do Brasil, 101, 1700-066, Lisboa, Portugal
3
Acustiprojecto Lda. [email protected], Lisboa, Portugal
Email: [email protected]
2
Abstract
A knowledge based system for the Portuguese code for Building Acoustics is under development.
The system is being developed using XPCE/SWI_PROLOG language. This specific PROLOG interpreter
was choosen because it provides both: An object oriented architecture linked to PROLOG and a good
interface to grapical objects. The XPCE Architecture is not PROLOG, however it is linked to PROLOG and
providing a very complete set of libraries for (graphical) user interfacing (GUI). It also provides object
oriented (OO) techniques, which are very well suited to handle the complexity of GUI components.
Since we are dealing with buildings and architectural shapes, GUI libraries were found very useful to
implement the 3D routines that can provide friendly 3D images so that the user can check if he is doing well.
The system provides calculations for the following acoustic parameters: 1) airborne sound transmission
through adjacent rooms and flanking contributions; calculation of Dn,w parameter, according to EN ISO –
12354 standard; 2) impact sound transmission through adjacent rooms and flanking contribution;calculation
of L’n,w parameter, according to EN ISO – 12354 standard; 3) sound insulation of façades; calculation of
D2m,n,w parameter; 4) reverberation time according to Sabine and Eyring Formulas.
The system provides a 3D interface to the user so that he can watch the rooms in which the acoustic field is
being studied.
The system uses object oriented techniques to provide construction elements that can be used in several
different situations. This option was choosen because it seemed similar to designing procedures for
buildings. In fact, building designers aim to rationalise projects, simplifying their options by choosing as few
types of construction elements as possible. Dispite the fact that the same construction element can be used
for different room configurations, only solutions that comply with regulations can be used.
Artificial Inteligence (AI) techniques are used at several levels inside the system, such as: 1) to recognise the
shapes of the adjacent rooms and choose the correspondent appropriate dimensions and algorithms for
calculation; 2) to impose some constraints to the 3D editor so that transmission between two rooms only can
exist if they are adjacent and separated by a wall or floor; 3) to ensure that the user selected options are as
much consistent as possible. For instance if a flexible element is selected only types of joints for flexible
walls can be selected.
Since the system is developed under the Prolog language, many other AI techniques and routines where
largely applied within the code.
The system provide a good interface to the user since he can see 3D images of the parts of the building under
acoustic simulation. He also can be confident of the results obtained since AI techniques are used to ensure
consistency of the simulations The link between AI and object-oriented techniques was found very usefull to
implement this system particularly when dealing with 3D objects.
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