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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. — 1110 —