To improve the allocation of funds for the maintenance and risk mitigation of transportation infrastructure, there is a dire need for a simplified, yet sufficiently accurate, methodology to estimate bridge vulnerability to scour. The methodology should make use of existing data and indicate the basic variables needed to assess the vulnerability of bridges located around a future expressway in southeastern Serbia. The first part of the paper discusses the identification of possible modes of bridge failure caused by scouring that depend on soil, structure, and river hydraulic properties. The degradation of soil parameters is assumed to be the main cause of bridge failure. The capacity of a bridge to withstand a certain amount of structural damage governs the direct and indirect costs attributable to bridge failure; the subsequent work zones related to rehabilitation reduce the performance of the whole network. In the second part of the paper, a simulation of the redistribution of traffic flows is described for several possible scenarios; the simulations use state-of-the-art software VISUM, which was developed for computer-aided transportation planning and analysis. The simulated scenarios include the partial and full closure of road links as a result of bridge failures. The simulations confirmed that the most significant contribution to indirect costs stems from the increase in the total travel time of all network users.
Paper production is one of the most energy intensive industrial processes. The use of waste heat is very important for energy efficiency improvement in paper industry. This paper deals with methods for calculation of potentials of waste heat generated in paper/board production process. For that purpose, the material and heat balance of the cardboard machine at Umka Cardboard Mill has been determined. Field measurements were conducted in order to define the unknown values of process parameters used for calculation in the balance equations and modelling. The focus was given to the cardboard drying section, which consumes most of the energy supplied to the machine. Additional aim of the work presented in the paper was to evaluate the specific energy consumption and the thermal efficiency of all individual energy units within the machine’s drying section. The results indicate two main sources of waste heat: waste heat released to the atmosphere with the discharge air from the present waste heat recovery system (14,380 kW); and waste heat released into the hall from the machine and extracted by the hall ventilation system (4,430 kW). Waste heat from both sources is characterized by fairly low temperatures 58-75ºС and fairly high moisture content (30-40 g/kg). The waste heat can be partly utilized for preheating the fresh air in cardboard drying process, saving up to 13% of steam consumption. The specific heat consumption and specific steam consumption (consumption per tonne of produced cardboard) of the machine was 1,490 kWh/t and 1.4 t/t, respectively. The thermal efficiency of drying section and coating drying section was 55.6% and 33.6%, respectively. All these figures imply necessity for further waste heat utilization with the aim of improving the efficiency of energy use
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