Studies on the application of gas cooling as used by firefighters

Gas cooling is a technique used by firefighters to create a safer work environment inside a compartment fire. By spraying water into the smoke layer, the smoke layer temperature will decrease significantly. Next to the lower temperature, the flammability of the smoke layer will also decrease. Due to the cooling of the fire gases, the smoke layer may contract. This work focused on different parameters that may affect the efficiency of gas cooling and was based on experiments. A series of tests were conducted inside an adjusted half-scale ISO9705 room. A rotatable nozzle was used to analyse different application methods, spraying times, spray angles and droplet size. Temperatures inside the room, velocities in the door opening and contraction of the smoke layer were measured. Out of the experimental results, the conclusion was made that there were no large differences between using the sweep or the pulsing method. There is no such thing as the one method that is the best way to apply the water spray to cool the overhead fire gases. When the fire gases must be cooled on a larger distance, pulsing will result in better cooling of the fire gases. The sweep is less influenced by the droplet size. So when the desired work pressure is not possible on the firefighter’s nozzle, and the ideal droplet sizes are not created, the cooling efficiency of the sweep method will be less influenced. The time between every spray must be as small as possible. It is better to open the nozzle once until enough water is applied into the smoke layer than open the nozzle multiple times for the same amount of water.Firefighters often have to perform an interior attack in pre-flashover conditions. Gas cooling is a control technique to create a safer work environment inside a compartment fire. By spraying water into the smoke layer, the smoke layer temperature will decrease significantly. Next to the lower temperature, the flammability of the smoke layer will also decrease. Due to the cooling of the fire gases, the smoke layer may contract. Gas cooling is performed in many countries around the world. Different methods are used to spray the water into the smoke layer. Two main methods are applied using a fog nozzle. In the Anglo-Saxon world pulsing is used by firefighters to put water into the smoke layer. Also in South-America, Hong Kong, West- and Central Europe etc. gas cooling is done using pulses. In the Scandinavian countries, gas cooling is done by sweeping the nozzle spray into the smoke layer. This work focused on different parameters that may affect the efficiency of gas cooling and was based on experiments. A series of tests were conducted inside a scaled test room in a lab environment. A rotatable nozzle was used to analyse different application methods, spraying times, spray angles and droplet size. Temperatures inside the room, velocities in the door opening and contraction of the smoke layer were measured. Overall there can be concluded that there is no such thing as the one method that is the best way to apply the water spray to cool the overhead fire gases. However, some minor differences between the pulsing and sweep method are noticeable. When a narrow spray cone is used to cool fire gases on a further reach, pulsing will have a better gas cooling efficiency. If the desired work pressure is not possible on the firefighter’s nozzle, and larger droplets are created, then the cooling efficiency of the sweep method will be less influenced. The time between every spray should be kept as small as possible. It is better to open the nozzle once until enough water is applied into the smoke layer than open the nozzle multiple times for the same amount of total used water

Thrombolysis and interventional cardiology; experiences from the 80's

In October 1978 I assumed the position of cardiologist at the Catharina Hospital in Eindhoven at the time when the cardiothoracic surgery programm began in this hospital. At that time I did not know the number of patients that had to be treated daily. During our fellowship training in cardiology, particularly in a university hospitaL there was time to discuss problems with teachers and to consid

Adsorption of a binary mixture of monomers with nearest-neighbour cooperative effects

A model for the adsorption of a binary mixture on a one-dimensional infinite lattice with nearest neighbour cooperative effects is considered. The particles of the two species are both monomers but differ in the repulsive interaction experienced by them when trying to adsorb. An exact expression for the coverage of the lattice is derived. In the jamming limit, it is a monotonic function of the ratio between the attempt frequencies of the two species, varying between the values corresponding to each of the two single species. This is in contrast with the results obtained in other models for the adsorption of particles of different sizes. The structure of the jamming state is also investigated.Comment: v2: Errors in the figures fixed; same text; 23 pages, 5 figures. Accepted for publication in Journal of Physics A: Mathematical and Genera

TARGET2 : le rôle d’un système d’aide à la décision pour compléter les fonctions de règlement.

Ce second article consacré à TARGET2 explique comment les outils d’aide à la décision mis à la disposition des banques centrales leur permettent d’assurer leur double rôle d’interlocuteur opérationnel de leurs participants et de surveillance.système d’aide à la décision, système de paiement, TARGET, TARGET2.

Understanding the Molecular Information Contained in Principal Component Analysis of Vibrational Spectra of Biological Systems

K-means clustering followed by Principal Component Analysis (PCA) is employed to analyse Raman spectroscopic maps of single biological cells. K-means clustering successfully identifies regions of cellular cytoplasm, nucleus and nucleoli, but the mean spectra do not differentiate their biochemical composition. The loadings of the principal components identified by PCA shed further light on the spectral basis for differentiation but they are complex and, as the number of spectra per cluster is imbalanced, particularly in the case of the nucleoli, the loadings under-represent the basis for differentiation of some cellular regions. Analysis of pure bio-molecules, both structurally and spectrally distinct, in the case of histone, ceramide and RNA, and similar in the case of the proteins albumin, collagen and histone, show the relative strong representation of spectrally sharp features in the spectral loadings, and the systematic variation of the loadings as one cluster becomes reduced in number. The more complex cellular environment is simulated by weighted sums of spectra, illustrating that although the loading become increasingly complex; their origin in a weighted sum of the constituent molecular components is still evident. Returning to the cellular analysis, the number of spectra per cluster is artificially balanced by increasing the weighting of the spectra of smaller number clusters. While it renders the PCA loading more complex for the three-way analysis, a pair wise analysis illustrates clear differences between the identified subcellular regions, and notably the molecular differences between nuclear and nucleoli regions are elucidated. Overall, the study demonstrates how appropriate consideration of the data available can improve the understanding of the information delivered by PCA

Proper scoring rules, gradients, divergences, and entropies for paths and time series

Many forecasts consist not of point predictions but concern the evolution of quantities. For example, a central bank might predict the interest rates during the next quarter, an epidemiologist might predict trajectories of infection rates, a clinician might predict the behaviour of medical markers over the next day, etc. The situation is further complicated since these forecasts sometimes only concern the approximate "shape of the future evolution" or "order of events". Formally, such forecasts can be seen as probability measures on spaces of equivalence classes of paths modulo time-parametrization. We leverage the statistical framework of proper scoring rules with classical mathematical results to derive a principled approach to decision making with such forecasts. In particular, we introduce notions of gradients, entropy, and divergence that are tailor-made to respect the underlying non-Euclidean structure

Series which are both max-plus and min-plus rational are unambiguous

Consider partial maps from the free monoid into the field of real numbers with a rational domain. We show that two families of such series are actually the same: the unambiguous rational series on the one hand, and the max-plus and min-plus rational series on the other hand. The decidability of equality was known to hold in both families with different proofs, so the above unifies the picture. We give an effective procedure to build an unambiguous automaton from a max-plus automaton and a min-plus one that recognize the same series