A Contribution to Fire Detection Modelling and Simulation

Computer simulations become more and more an important tool in the field of automatic fire detection. An over all model of the automatic fire detection shall give the opportunity to simulated the process of fire detection including the fire, the fire sensor and the processing of the sensor signal. For the different parts of the over all model realisations exist. There are different types of fire models and models for fire sensors. But these are separate models. To allow the simulation of a fire sensor signal from the fire up to the response of the sensor the models have to be combined. One model to simulate fires is the Fire Dynamics Simulator (FDS) developed at the National Institute of Standards and Technology. This model is combined with a fire sensor model, that simulates the response of a fire sensor to a given fire situation, which is defined by the input parameters of the sensor model. For this combination an interface between the two models is build up. Inside this interface the output parameters of the fire model are converted to the necessary input parameters of the sensor model. In the first approach only smoke sensor are considered. For the simulation of the smoke development during a fire the fire model gives informations about the smoke mass density as results. The smoke sensor model needs informations about the size distribution of the smoke particles. So the different parameters have to be converted. Therefore mechanisms which influence the particle size distribution but not the smoke mass density have to be implemented in the interface. The combined fire and smoke-sensor model is verified by applying it to EN54 testfires and gives the possibility to simulate the response of different types of smoke sensors to a fire or a non-fire situation

Stable isotope (δ18O and δ13C) sclerochronology of Callovian (Middle Jurassic) bivalves (Gryphaea (Bilobissa) dilobotes) and belemnites (Cylindroteuthis puzosiana) from the Peterborough Member of the Oxford Clay Formation (Cambridgeshire, England): Evidence of palaeoclimate, water depth and belemnite behaviour

Incremental δ18O and δ13C signals were obtained from three well-preserved specimens of Cylindroteuthis puzosiana and from three well-preserved specimens of Gryphaea (Bilobissa) dilobotes from the Peterborough Member of the Oxford Clay Formation (Cambridgeshire, England). Through-ontogeny (sclerochronological) δ18O data from G. (B.) dilobotes appear to faithfully record seasonal temperature variations in benthic Callovian waters of the study area, which range from c. 14 °C to c. 17 °C (arithmetic mean temperature c. 15 °C). Water depth is estimated to have been in the region of c. 50 m, based upon comparisons between these data, previously published non-incremental sea surface δ18O values, and a modern analogue situation. Productivity in Callovian waters was comparable with that in modern seas, based upon δ13C data from G. (B.)dilobotes, with 13C depletion occurring during warmer periods, possibly related to an interaction between plankton blooms and intra-annual variations in mixing across a thermocline. Incremental δ18O data from C.puzosiana provide temperature minima of c.11 °C for all specimens but with maxima varying between c.14 °C and c.16 °C for different individuals (arithmetic mean values c. 13 °C). Temperatures for late ontogeny, when the C. puzosiana individuals must have been living close to the study site and hence the analysed specimens of G. (B.) dilobotes, are closely comparable to those indicated by the latter. However, for significant portions of ontogeny C. puzosiana experienced temperatures between c. 2 °C and c. 3 °C cooler than the winter minimum as recorded by co-occurring G. (B.) dilobotes. Comparisons with modern seas suggest that descent to a depth of c. 1000 m would be necessary to explain such cool minimum temperatures. This can be discounted due to the lack of deep waters locally and due to estimates of the depth tolerance of belemnites. The most likely cause of cool δ18O signals from C. puzosiana is a cosmopolitan lifestyle including migration to more northerly latitudes. Mean δ13C values from C. puzosiana are comparable with those from G.(B.)dilobotes. However, the incrementally acquired data are highly variable and probably influenced by metabolic effects.The probable identification of migratory behaviour in C. puzosiana calls into question the reliability of some belemnite species as place-specific palaeoenvironmental archives and highlights the benefits of adopting a sclerochronological approach

The role of biogeography and ecology on the isotope signature of cuttlefishes (Cephalopoda, Sepiidae) and the impact on belemnite studies

Calcitic belemnite guards are often used for temperature reconstructions of ancient seawater by using oxygen isotope thermometry. These geochemical studies discuss diagenesis and vital effects but neglect ecological or biogeographic effects on the isotope signature. To estimate the impact of seasonal temperature variations, short-term salinity changes and biogeography on the isotope signals we compare the δ18O and δ13C signals of ten cuttlebones with local water temperatures. The cuttlebones (aragonitic internal shells) come from five different species of recent cuttlefish (Sepiidae, Sepia sp.) from seven different regions (North Sea, Baltic Sea, Mediterranean, Red Sea, Angola, North Australia and Tasmania). All analysed specimens reflect the temperature-characteristics of their habitat perfectly. The δ18O signal and calculated temperatures follow annual temperature changes of up to 15 °C. The δ13C values show no clear pattern and are thought to be controlled by vital effects. Freshwater influence is recognizable in the negative δ18O and δ13C values of the Baltic Sea specimen, although sudden short-term salinity changes are not reflected by the signatures

Stable isotope records from Sepia officinalis—a key to understanding the ecology of belemnites?

The stable isotope ratios (δ18O, δ13C) of the aragonite of cuttlebones of Sepia officinalis were measured on a high resolution scale where every septum was measured. Our studies aim at understanding whether variations of the isotope signature are controlled by ontogenetic and/or ecological factors. Five specimens were reared from eggs under known water temperatures, a sixth specimen was caught in the German part of the North Sea. The data suggest that the oxygen isotope composition is in isotopic equilibrium with the surrounding seawater and reflects ambient temperature. Migration and seasonal temperature changes are visible in the acquired data set. The carbon isotope signature shows signs of biofractionation and no direct correlation to the oxygen signature as far as ontogeny and ecology are concerned