Nikola Tanasić

Vulnerability Assessment of Bridges Exposed to Scour

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.

Energy audit as a tool for improving overal energy efficiency in Serbian industrial sector

The paper presents characteristics of energy consumption in industrial sector of Serbia, the methodology and results of energy audits (EA) performed in industrial sites and potentials for energy efficiency (EE) improvements. The present state of industrial energy in Serbia could be characterized by significant technological out-of-date, low EE and low level of environmental protection. Presented analysis of the results of conducted EAs in selected industrial companies in previous period has shown the significant potentials for EE improvements in Serbian industrial sector (upgrading or replacement of equipment in the industrial energy sources and processes, introduction of energy management, improvement of steam supply and condensate return systems, the waste heat utilization, introduction of EE technology, improvement of EE in electrical equipment, usage of waste materials etc).

Management of bridges with shallow foundations exposed to local scour

Abstract The Serbian road network includes a large portion of bridges with shallow foundations vulnerable to local scour as tragically demonstrated during the extreme flooding in May 2014. Currently, the bridge management procedures in Serbia and worldwide do not comprehensively account for a risk of bridge failure due to flooding and fail to provide sufficient information for the decision-making. Thus, a novel methodology for quantitative vulnerability assessment is suggested as a tool to identify the most vulnerable bridges in a network. Herein, the essential task is evaluation of the conditional probability of a bridge failure due to local scour in a flooding event of a certain magnitude. To apply this approach on a network level, there is a dire need to establish precise practice-ready guidelines on an optimal set of information to be used and/or collected in situ, which is discussed on an example of the Serbian bridge database. The vulnerability of a bridge to local scour may be used as a comprehensive indicator of a bridge performance in a flooding event. For a network level, the vulnerability maps with respect to flooding of different magnitudes will give road operators crucial information to apply adequate quality control plans to vulnerable bridges.

Energy management system for energy efficiency improvement in the industrial sector of the republic of Serbia

Main primary energy sources in Serbia are coal, oil and natural gas, oil shale and renewable energy sources. The share of high quality primary energy sources (oil and natural gas) is less than 1% of total geological reserves, while the rest of 99% consists of different types of coal, with highest share of lignite - over 95%. Estimated technically available renewable energy sources potential in Serbia is 5.65 Mtoe, where 1.054 Mtoe of biomass and 0.909 Mtoe of hidro-power are already used. Speaking of energy efficiency in final energy consumption sectors of the Republic of Serbia holds unenviable position comparing to EU countries. Since 2000 there is series of strategic and legal documents that are adopted and they are governing the operation of energy sector as well as implementation of energy policy at state level. The Law on energy efficiency was adopted in March 2013. It regulates implementation of energy management system within industrial sector, on the local level (cities and municipalities) as well as in public buildings sector. The purpose of secondary legislative is to define, in more details, terms for obtaining status of designated company within the system for energy management in industrial sector and in public companies, training programs for energy managers, as well as method of appointing energy managers in designated companies.

Results of experimental research on parameters that determine stable operating limits of ceramic burner with packed bed of uniform spheres for combustion of low calorific gaseous fuels

The research presented in this paper focuses on parameters that determine stable operating limits of porous burner. The experimental research was carried out on laboratory installation consisting of ceramic cylinder filled with packed bed of Al2O3 spheres. Gaseous fuel is prepared by mixing the compressed natural gas (CNG) and nitrogen (N2) in defined ratio, depending on set heating value of the inlet gaseous fuel. Experimental program included combustion of low calorific gaseous fuel (7.5 to 15 MJ/m3) within porous burner, where inlet power ranged between 2 and 4 kW. Total number of experimental sets in experimental study was 16, where seven of them were considered as stable. Results of experimental research are presented and discussed within this paper.

Potentials for reducing primary energy consumption through energy audit in the packaging paper factory

Energy audit is a primary step towards a more rational use of primary energy sources in the energy-intensive process such as the production of packaging paper. By the adoption of the Law on efficient use of energy in 2013, energy audits have become mandatory for all industrial companies in Serbia. This paper presents the methodology and results of the one-day energy audit which was conducted in the Paper Factory - Belgrade (FHB). The measures to increase energy efficiency of the production process, together with the quantification of the savings in the primary energy consumption, are proposed based on the results of the study.

Review of technical standards and calculation methods for dimensioning of smoke and heat control systems in case of fire in underground car parks

Smoke and heat exhaust ventilation systems create a smoke free layer above a floor by removing smoke. They can, therefore, improve conditions to allow the safe escape and rescue of people, to protect property and to permit a fire to be fought while still in its early stages. Ventilation systems for smoke removal also serve simultaneously for heat exhaust and can exhaust hot gases released by a fire, thus controlling the temperature in the room affected by the fire. The paper reviews international and domestic standards as well as domestic regulations that are relevant for the fire protection of underground car parks. Recommendations and calculation methods for dimensioning of mechanical smoke and heat exhaust ventilation systems in case of fire in underground car parks are discussed in the paper. Calculation examples of dimensioning of this systems for different case studies are also included in the paper.

Experimental study on the efficiency of pulverized coal-fired steam boiler

The results of experimental investigation of pulverized coal combustion process with the aim to improve energy efficiency of an industrial steam boiler are presented in the paper. The investigation included measurement of combustion process parameters in four typical operating conditions, from minimum to maximum steam boiler load, and visualization of combustion process by using the camera with thermal imaging sensor. Several organizational and technical measures to improve energy efficiency of the industrial steam boiler are proposed and discussed in the paper. The measures are evaluated in terms of a possible reduction in the coal consumption and CO2 emissions.

Effect of small deviation of incident angle on thermal performance of parabolic-trough solar collector

The paper analyzes the effect of small deviation of incident angle relative to the focal plane on thermal performance of parabolic-trough solar collector. Decrease of solar collector thermal output is presented in form of coefficient of performance i.e. function of the incident angle deviation. In solar collector operation mode, working fluid (e.g. water) can become overheated. In that case, decreasing the thermal output would influence temperature drop of working fluid. Rotation of a parabola for a small angle relative to the focal plane will decrease the output thermal power of the solar collector. This analysis contributes to calculate deviation of incident angle relative to the focal plane in order to achieve the given thermal output for defined input parameters - collector type, local and real conditions (i.e. Sun position, orientation, time and date). In this paper, two-dimensional analytic geometry was used as a basic methodology for calculations and simulations.

Airflow measurements and mass and heat balance in a cardboard mill hall to approach energy efficiency

The results of field measurements conducted in Umka Cardboard Mill hall are presented in the paper. The points of interest were air temperature and humidity distribution inside the hall as well as the temperatures of the cardboard machine surfaces and inner walls of the hall. Temperature, humidity and velocity of air at supply-air openings were also measured. Based on the results material and heat balance of the hall was calculated and discussed. The aims of the study were to evaluate the thermodynamic properties and waste heat potentials of the air extracted from the hall by mechanical ventilation system.