Jan Glasa

On elliptical model for forest fire spread modeling and simulation

A new approach for the derivation of elliptical model of steady-state forest fire spread in time based on classical envelope theory is described. The derivation of this model known in the literature is based on the introduction of a special transform of co-ordinate system which allows to utilize geometrical properties of points lying on common tangent line of two circles. However, the use of this transform means the necessity to apply some specific assumptions onto the model. The proposed new procedure allows us to derive the model without the use of this transform. The new approach enables to better explain the internal coherence of studied problem, assumptions and limitations of the model, as well as to suggest its further generalizations.

Computer Modelling of Automobile Fires

The use of the CFD (Computer Fluid Dynamics) theory and its practical knowledge has become widespread in such academic disciplines as aerodynamics, fluid dynamics, combustion engineering and other fields. However, in the disciplines, which examine the ongoing processes in larger sizes, CFD was applied during the last decades only. One of such discipline is a spread of fire. Fire processes are a very complicated and complex phenomenon consisting of combustion, radiation, turbulence, fluid dynamics and other physical and chemical processes. A good knowledge about complex phenomena and processes occurring during fire in different environments is a significant component of fire safety. As fire itself is very complicated phenomenon, interdisciplinary approach to the problem is required.

Cinema Fire Modelling by FDS

Recent advances in computer fluid dynamics (CFD) and rapid increase of computational power of current computers have led to the development of CFD models capable to describe fire in complex geometries incorporating a wide variety of physical phenomena related to fire. In this paper, we demonstrate the use of Fire Dynamics Simulator (FDS) for cinema fire modelling. FDS is an advanced CFD system intended for simulation of the fire and smoke spread and prediction of thermal flows, toxic substances concentrations and other relevant parameters of fire. The course of fire in a cinema hall is described focusing on related safety risks. Fire properties of flammable materials used in the simulation were determined by laboratory measurements and validated by fire tests and computer simulations

Automobile interior fire and its spread to an adjacent vehicle: parallel simulation

Knowledge of the course of an automobile fire is an important issue in automobile fire safety and can have a significant impact on fire safety measures in car parks and other structures with a high concentration of automobiles. In this article, computer simulations of fire in an automobile interior and its influence on an adjacent vehicle are investigated. The results of simulations are compared with the results of the measurements obtained during a full-scale fire experiment conducted in Povazsky Chlmec (Slovakia) in 2009. The comparison confirms the accuracy of the simulation. A parameter study related to some selected material properties, which shows that seat material properties are the most important for the fire development, is described. Due to high computational requirements, a parallel version of the calculation is studied, and the influence of parallelization on performance and accuracy is tested as well. As the glass breakage is one of the most important factors affecting the course of an automobile fire, a simple practical criterion to determine when window breakage will occur is proposed.

Bit-level systolic arrays for digital contour smoothing

The paper deals with the analysis of bit-level systolic arrays for digital contour smoothing. Procedures for obtaining new bit-level systolic arrays, which improve the already known designs, were suggested. New systolic arrays proposed on the bit level have a simple structure. They consist of single type cells (1-bit full adders), which are separated by 1-bit delay elements. They are suitable for the VLSI implementation.

On Bit-Level Systolic Arrays for Least-Squares Digital Contour Smoothing

In this paper bit-level systolic arrays for the least-squares digital contour smoothing are described. The smoothing is represented by linear operators defined by sparse circulant Toeplitz matrices with integer coefficients. A suitable decomposition of such matrices allows to analyze different bit-level pipelined strategies of the computation and to suggest corresponding bit-level systolic arrays which have a simple regular structure and achieve very high throughputs.

Impact of Turned Cars in Tunnel on Modelling People Evacuation in Fire Conditions

People evacuation in tunnel in fire conditions belongs to important tunnel safety problems. In this paper, simulation of fire in a short unidirectional 2-lane road tunnel and its evacuation using the FDS+Evac system are analysed. FDS+Evac enables to simulate fire spread in the tunnel utilizing the obtained fire characteristics for modelling evacuation of people. Three evacuation scenarios which differ from each other by cars location in the tunnel are illustrated. The impact of turned cars on fire spread and people egress is demonstrated. Some specific particularities of the current version of FDS+Evac, which must be taken into account in modelling the egress in tunnel fire conditions to avoid misrepresentation of input representation, are discussed.

Least-squares smoothing of 3D digital curves

In this paper an efficient procedure for 3D digital curve smoothing is presented. It is described by linear operators which allow to perform the constrained, position invariant, least-squares smoothing of 3D digital curves minimizing the undersampling, digitizing and quantizing error and to calculate various curve characteristics and invariants related to the original digitized curve. They are represented by sparse symmetric circulant Toeplitz matrices with integer coefficients which can be efficiently realized in serial as well as in parallel manner.