Product form of inverses of sparse matrices Progress report

Product form of inverses of sparse matrices - matrix algebra and linear programming code

Direct methods for the solution of systems of linear equations with sparse coefficient matrix and related topics Final report, 1 Dec. 1967 - 31 Aug. 1970

Deriving algorithms for computations involving sparse matrice

Sorting and ordering sparse linear systems

Transformations of sparse linear systems by row-column permutations are considered and various algorithms are constructed to transform arbitrary symmetric positive definite sparse matrices, as well as matrices in band form, doubly bordered band form, and doubly bordered block diagonal form

Effects of the generic nature of polymers on their fire behavior

International audienceFire behavior of four aliphatic and two aromatic C, H, O, N, S, and Cl atom containing polymers has been examined. Experiments were performed in three ASTM E 2058 Fire Propagation Apparatuses. The differences in the ignition behavior of polymers were found to be mainly due to differences in the ignition temperature. Chemical effects appear to contribute about 25 % towards the ignition resistance of the polymers. For thermoplastics, formation of polymer melt and its burning as a pool fire was found to increase the fire intensity by factors of two to four. The combustion efficiency and generation efficiency of CO2 were found to decrease and the generation efficiencies of CO and smoke were found to increase by changes in the generic nature of the polymers (aliphatic to aromatic to halogenated). About four times as much carbon atoms in the polymers converted to smoke than converted to CO. Large-scale fire propagation behavior of polymers was characterized by a Fire Propagation Index (FPI). The FPI values of melting type thermoplastics (showing rapid-fire propagation behavior) were high, whereas they were low for the engineered charring type and halogenated polymers (showing either slow or decelerating fire propagation behavior)

An analysis of some practical methods for estimating heats of combustion in fire safety studies

The theoretical (net) heat of combustion of materials is a basic information important for fire safety studies. This paper is a review of existing methods ranging from use of tabulated data to calculations relying on more or less sophisticated engineering correlations based on the elemental compositions of materials and in some cases on their chemical structures. The presentation emphasises only those calculation methods that allow user-friendly estimations of the heats of combustion, that is to say when at most a simple datasheet processor is the only tool required. Empirical correlations developed in early times of combustion science by Dulong (France), Boie (Germany) and some others are examined here in the context of fire engineering. More recently proposed predictive methods of heats of combustion in fire or chemical engineering background, taking account of structural effects of the molecules on their heats of combustion are then presented and compared. Finally, consideration of the relevance and accuracy of the listed methods is provided and commented either by comparison of literature and calculated values, either by reference to measured data obtained by use of conventional oxygen bomb calorimetry

Accurate calculations of heat release in fires

Fire is often considered as the most hazardous accidental event which may affect safety in the chemical industries. The fire damage may be thermal or non thermal. As examples, the fire plume may transport a variety of toxic effluents, which may injure the staff of the industrial premises and the fire fighters, as well as the inhabitants in the neighbourhood. Intense radiation produced by big fires may cause serious burn injuries and generate "domino effects" to previously non affected equipment in the vicinity and result in related phenomena such as jetfires, fireballs, BLEVEs1 . Moreover, polluted extinction waters while unconfined may greatly affect the aquatic environment. Although several ambitious projects were recently carried out in the field, there is still much work to be performed to get validated techniques capable of predicting (and keeping under acceptable control) the consequences of indoor and outdoor large chemical fires

Fire safety assessment of open wide gangway underground trains in tunnels using coupled fire and evacuation simulation

A new type of train configuration, known as Open Wide Gangway (OWG) is becoming popular, particularly in underground environments. Previous fire modelling analysis demonstrated that the OWG configuration was considered safe as or safer than conventional configurations as it reduced the likelihood of flashover. However, these studies have ignored the impact on evacuation of the spread of fire effluent to non-fire cars. Here we explore the fire safety offered by conventional and OWG configurations using coupled fire and evacuation modelling techniques. Two tunnel train situations are considered; one in which the car side doors are available for evacuation (train in a wide tunnel) and the other in which only the end cab doors are available (train in a narrow tunnel). Two population configurations are considered, fully and half loaded. Two ignition sources are also considered, one representing an accidental fire and the other an arson fire. The analysis demonstrates that while the OWG configuration may produce improved fire performance in the car of fire origin compared to the conventional configuration, if the interaction of the fire effluent with the evacuating passengers is considered, the OWG configuration results in a significantly greater number of casualties in virtually all the scenarios considered

Solution of a generalized diffusion equation by difference methods

Thesis (Ph.D.)--Boston Universit