Novel Approach in Tunnel Safety Assessment

The definition of a deterministic approach to risk analysis stems from the need to understand the conditions that are developed in the event of an accident with a fire in a road tunnel. From the point of view of the tunnel manager and rescuers, these data are important during planning the operation of the tunnel and in coordinating the rescue. The methods of tunnel control in crisis situations are most often based on the experience of operators and crisis plans, which are also made by experience or using simple calculation tools. In recent years, due to many tragic accidents in European tunnels, there has been a lot of talk and work in the field of risk assessment and the possibilities of risk reduction. The methodology of safety analyses and the determination of the level of risk arise predominantly from the nuclear and chemical industry, where it has been in use for more than 50 years. The paper presents the methodology for integrating methods of rapid processing of risk assessment with time-consuming CFD methods for analysing the consequences of fire in the tunnel safety assessment process. The main observed variables are the density and the temperature of the carbon black, which are analysed during the fire step in a minute. Human behaviour is considered in the evacuation model, which is necessary for the assessment of fatalities during the progress of the fire. The use of the methodology is presented by assessing the national tolerable risk for transport in tunnels and compared to the EU reference criteria

Nonequilibrium quantum dynamics of a charge carrier doped into a Mott insulator

We study real-time dynamics of a charge carrier introduced into undoped Mott insulator propagating under a constant electric field F on the t-J ladder and square lattice. We calculate quasistationary current. In both systems adiabatic regime is observed followed by the positive differential resistivity (PDR) at moderate fields where carrier mobility is determined. Quantitative differences between ladder and 2-dimensional (2D) system emerge when at large fields both systems enter negative differential resistivity (NDR) regime. In the ladder system Bloch-like oscillations prevail, while in 2D the current remains finite, proportional to 1/F. The crossover between PDR and NDR regime in 2D is accompanied by a change of the spatial structure of the propagating spin polaron

AN ENHANCED EQUATION FOR VIBRATION PREDICTION OF NEW TYPES OF SHIPS

A simplified approach developed to evaluate the vibration levels of complex structures such as passenger and similar ships with large shell and deck openings and extended superstructures is here presented. The final objective is to give an useful tool to ship designers, to establish since the first design stage the dynamic response of the ship with sufficient precision. This approach is based on the assumption that the ship hull can be represented as a non uniform section beam. The propeller excitations in terms of pressure pulses and shaft line moments and forces are introduced. To take into account this exciting source in the early design stage a statistical formula for dynamic excitation of propeller was developed. Furthermore the superimposition of local effects has been performed with the use of an analytical formula. The local effect due to the different space topologies such as cabins, public spaces, technical and machinery areas has been taken into account. The transversal beams, longitudinal girders, stiffeners and pillars as supported structural elements are considered in the vibration local response. The reliability of the results obtained using the formula has been improved with more precise results obtained by FEM analysis. The calculated vibration response has been verified and compared to vibration measurements performed on board of ships

Upgrade of a transverse ventilation system in a bi-directional tunnel

The Karavanke tunnel forms an important link between Slovenia and Austria. The almost 8 km long tunnel is operated with bi-directional traffic and does not have dedicated escape routes. Moreover, the ventilation in case of fire does not satisfy requirements of the EU Directive 2004/54/EC that specifies the minimum requirements for tunnels in the trans-European road network. The paper present results of the research conducted regarding the possibility of upgrade the existing system in order to reach the required level of safety at lower costs possible. It is shown that with simple but novel adaptations of the ventilation system, a sizeable increase in the overall level of safety can be achieved. The methodology applied is a combination of a simple pipe model for tunnel ventilation and for detailed fluid dynamics analysis the CFD model is used. The existing ventilation system that in fire ventilation extracts smoke from a single duct is replaced with the smoke extraction from both ducts applying four axial fans. The analysis is focused on air/smoke flow through the vents and ducts and on pressure drops calculated over the length of the ventilation duct and its influence on the total flow. The change of the flow condition also has influence on ventilation fan operation point that is investigated in the paper as well

Outline scheme of the road crossing Macesnik landslide

This thesis discusses the reconstruction of the damaged road across Macesnik landslide. Roads RT-926/5501 (Solčava-Podolševa-Sleme) and RT-927/5502 (Žibrovt-Sv. Duh-Podolševa) go across the landslide. In this thesis an outline scheme of the reconstruction or rebuilding of two parts of the road that have been damaged by the Macesnik landslide during the years 1994 and 1996 is presented. When \ud building this kind of road the basic problems usually occur when crossing the landslide terrain where certain conditions concerning the drainage of the roadway, the bearing capacity of the soil, the road weight and limited possibility of entrenchments and embankments must be followed. Designing of both new road sections is based on Rules on Road Design and Technical Specification for Road Works, it is designed with the help of computer programs AutoCad and Plateia on the whole. A new road construction situation, longitudinal and transverse sections, normal and characteristic crosssections are shown. At the end a survey of works and an approximate preliminary assessment of costs are also introduced

Estimation of Forces Acting on a Sailboat Using a Kinematic Sensor

Amateur keel boat racing has become increasingly popular in coastal regions with a long sailing tradition, such as the Adriatic. Although the traditional experience is transferred to new generations of skippers and crews that compete in national and international regattas with open class boats, the material limits of the boat are often measured subjectively, by sail or mast failure, and transferred through a story. Most sailors know why a component failed, but often they do not know what force was needed for the particular failure. Forces acting on a boat are usually estimated with CFD and towing tank experiment for relevant sailing conditions, but full scale data in seaway are rarely taken. Here we want to show a low budget method to get a rough estimate of aerodynamic and hydrodynamic forces acting on a keel sailboat using a kinematic sensor. Some approximations are taken into account to construct a simplified mathematical sailboat model, which allow to relate kinematic data to forces acting on the sail, hull, keel, and rudder. Some data such as the geometry and mass distribution of the boat has to be known; other parameters such as water resistance instead has to be experimentally measured. The results of a series of measurements are presented and discussed. Looking on the limitations of such a method, a proposal for a new sensor is made

Povećanje kompetitivne prednosti kroz optimizaciju opskrbljujućih lanaca kontejneriziranih tokova robe

The basic aim of this treatise is to research into relevant features of the multimodal transportation chains, their advantages and disadvantages as well as the problems of the sinchronization of work of all participants in multimodal transport. With the development of information technology the method of optimisation of the multimodal transportation chains is more and more based on the computer programs being representative tools in solving of the comprehensive tasks. It is believed that the present research, the methodology applied and its findings, should promote and improve the multimodal transportation chains in order to cope with the complex contemporary logistic demands of global economy.Osnovni cilj članku je istraživati relevantne faktore multimodalnih transportnih lanaca, njihovih prednosti i slabosti, ali i probleme sinkronizacije rada svih sudionika u multimodalnom transportu. Razvoj informacijskih tehnologija i metoda optimalizacije multimodalnih transportnih lanaca sve se više temelji na kompjutorskim programima koji su reprezentativna sredstva u procesu rješavanja složenih transportnih problema. Vjeruje se da će sadašnje istraživanje, aplicirana metodologija i rješenja unaprijediti multimodalne transportne lance poradi zadovoljavanja kompleksnih sadašnjih i budućih logističkih zahtjeva globalne ekonomije