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It is commonplace in industrial installations to have duct vented vessels, the design of which is often based upon the premise that central ignition will provide the worst case scenario. This research investigates duct-vented explosions using a vented test chamber of 200 l capacity fitted with a 1m long vent pipe, discharging into a large (50 m 3 ) dump volume with rear and central ignition. Propane-air mixtures over a range of concentrations (Ф=0.8-1.6) have been used. Results show that while there is no significant difference in maximum pressure in the test vessel for rear and central ignition, rear ignition consistently produces the worst case in terms of rates of pressure rise and flame-speeds in the duct. In addition, the detailed records of pressure traces and flame position showed a direct relationship between the induced gas velocity in the duct prior to the flame arrival and the subsequent rate of pressure rise in the vessel. The implications of the findings for practical systems are briefly discussed.

Computational Fluid Dynamics (CFD) codes are widely used for gas dispersion studies on offshore installations. The majority of these codes use single-block Cartesian grids with the porosity/distributed-resistance (PDR) approach to model small geometric details. Computational cost of this approach is low since small-scale obstacles are not resolved on the computational mesh. However, there are some uncertainties regarding this approach, especially in terms of grid dependency and turbulence generated from complex objects. An alternative approach, which can be implemented in generalpurpose CFD codes, is to use body-fitted grids for medium to large-scale objects whilst combining multiple small-scale obstacles in close proximity and using porous media models to represent blockage effects. This approach is validated in this study, by comparing numerical predictions with large-scale gas dispersion experiments carried out in DNV GLs Spadeadam test site. Gas concentrations and gas cloud volumes obtained from simulations are compared with measurements. These simulations are performed using the commercially available ANSYS CFX, which is a general-purpose CFD code. For comparison, further simulations are performed using CFX where smallscale objects are explicitly resolved. The aim of this work is to evaluate the accuracy and efficiency of these different geometry modelling approaches.

We present to the international scientific community three important works by Father Maccioni adapted into English with several parts literally translated. The investigation into the existence of an electromagnetic (EM) seismic precursor was carried on in Italy in the beginning of the twentieth century and exploited the capabilities of a specifically designed coherer. For several reasons, both the work and the author are widely unknown even in Italy. We think this is likely to be the very first historical case of a study of a seismic precursor of the EM type.