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This paper suggests a practical method, based on multi-domain BEM, to calculate the transmission loss of 3-dimensional silencers of subdomains comprised of different geometric and material characteristics with looped and/or cascaded connections. We previously proposed an efficient method to compute the transmission loss for 3-dimensional silencers using multi-domain BEM but its application is much difficult to those having looped subdomains [l]. Here, we adopt a method summing the impedance matrices of the subdomains with various types of connection represented by system graph. The algebraic overall condensed acoustic equations having only particle velocities on the subdomain interface boundaries as unknowns are formulated. A splitter silencer of cascaded, looped and symmetric connections as a sample problem is dealt with for the explanation and verificationof the proposed method. An experimental work with the splitter silencer is performed to back lip the suggested method.

As the examples of smoke spread in a corridor, the burn rooms are generally connected through a corridor to environment and a lobby. The wave amplitudes of the velocity of transient jet waves are very important in fire protection systems. The objectives of this study are to estimate mathematically the parameters of the transient jet wave velocities flowing through the unconfined ceiling of the corridor and to derive various related equations with the parameters. The parameters vary according to the wave induced velocity, the natural frequency, the wave number and the mean flow velocity. The transient ceiling jet waves are analyzed by FDS software developed by the National Institute of Standards and Technology, USA. The analyzed results of the smoke layer temperature are compared with the experimental results performed by Jones et al.. The relation of the mean velocity, the heat release rates and the door width is expressed by the relation of the wave induced velocity, the heat release rates and the door width is expressed by .