A life cycle energy assessment for biogas energy in Serbia

The aim of this paper was to present the energy flows in the life cycle of biogas utilization systems (cogeneration and transportation), as well as their mutual relations, starting from providing the feedstock for digestion through to end-of-life management of biogas system as fertilizer on agricultural land. This study was carried out through the energy analysis of two scenarios (biogas in cogeneration and biogas in transportation) using performance of Mirotin biogas plant (1 MW) in Serbia. Results obtained in this study have shown that the analyzed scenario (biogas in cogeneration and biogas in transportation) have positive energy balances (52,114 and 53,585 GJ) and these scenarios are sustainable from energetic point of view.     

Analytical Support for Integrated Water Resources Management: A New Method for Addressing Spatial and Temporal Variability

This paper discusses the development of an analytical support system for implementation of the Integrated Water Resources Management (IWRM) process. The system integrates four analytical tools: (i) geographic information system; (ii) system dynamics simulation; (iii) agent-based model; and (iv) hydrologic simulation. The choice of tools is driven by their ability to (a) respond to the main requirements of the IWRM and (b) explicitly describe system behaviour as function of time and location in space. The system dynamics simulation captures temporal dynamics in an integrated feedback model that includes sectors representing physical and socioeconomic system components. Management policies established in the participatory decision making environment are easily investigated through the simulation of system behaviour. Agent-based model is used to analyze spatial dynamics of complex physical-social-economic-biologic system. The IWRM support system is tested using data from the Upper Thames River Watershed, Ontario, Canada, in collaboration with the Upper Thames River Conservation Authority.     

Two New Non-structural Measures for Sustainable Management of Floods

Abstract

Modern flood mitigation is increasingly non-structural. Well-established, traditional non-structural measures such as zoning, building codes, flood proofing, early detection and warning, emergency planning, flood insurance, etc., appear today as indispensable complements to structural engineering solutions. Advancement of computer sciences and communications provides an opportunity for further broadening of the context of non-structural flood mitigation. Two new concepts, a flood management virtual database and a flood management decision support system, are presented in the paper. Their benefits are demonstrated through the development of prototype systems for the Red River basin in Manitoba, Canada. First, it is shown that the Internet technology is mature enough to support the development of virtual database for a complex domain such as floodplain management. It is also quite clear that this mode of support has many advantages when compared to more traditional centralized database model. Secondly, we concluded that the decision support system approach provides an opportunity to meet the expressed needs of residents living in flood-prone areas for improvement in the flood management and a major change in the decision-making process. A decision support system is envisioned as a tool for analyzing alternative mitigation and recovery strategies. It is proposed in this work as a way of making flood management process more transparent and efficient in reducing future economic, environmental, and social flood damages.     

Sensitivity of reservoir operation performance to climatic change

The potential impacts of changing climatic conditions on the operational performance of water resource systems was investigated in this paper. A multi-site streamflow generation model was used to synthesize potential monthly flow sequences reflecting two different sets of climatic conditions. The generated data were subsequently employed as input to a reservoir operation model that was used to determine the reservoir response to the inflow resulting from the implementation of the reservoir operating policy. The performance of an example reservoir system, the Shellmouth Reservoir located in the Canadian province of Manitoba, was evaluated and compared for the two sets of conditions. The operational performance was evaluated in terms of the reliability of the system for meeting the three purposes of the actual reservoir. The reservoir performance was determined to be sensitive to the inflow data. The results indicate that climatic change has potentially important implications for the operation of the example reservoir system.     

A New Post-filter Algorithm Combined with Two-step Adaptive Beamformer

The optimal microphone array, in the sense of minimum mean square errors (MMSE), includes two processing blocks: the minimum variance distortionless response (MVDR) beamformer and the single-channel Wiener filter, which acts as post-filter. In this paper, we propose a new post-filter algorithm based on assumptions that both the noise power attenuation factor (NPAF) and signal power attenuation factor (SPAF) are time invariant in the reverberant room. The algorithm recursively estimates both factors from available measurements and uses them in estimation of the post-filter parameters. Additionally, to overcome the problem of the poor performance of the MVDR beamformer in reverberant conditions, we propose the usage of the two-step (TS) MVDR algorithm. This algorithm improves the robustness of the beamformer and its ability to suppress the interferences using an estimate of the desired speaker transfer function. Although TS MVDR beamformer and proposed post-filter can work separately, or combined with other algorithms, the best performance is obtained when they work together. The performance of the proposed combination of new post-filter algorithm and TS MVDR beamformer is tested in a simulated reverberant room and compared with similar algorithms, which gave rather good results.     

Sustainable development of lignite production on open cast mines in Serbia

Energy sector represents a key industrial branch for national, environmental and economic success. With its exclusive access to domestic deposits, lignite industry represents a guarantor of reliable raw materials, offering long-term supply security based on verified reserves. Currently operated coalmines in Serbia (Kolubara and Kostolac) have production around 36 million tons of lignite, and over 108 million m3 of overburden. Consequently, sustainability of lignite production requires cost reduction and environmental protection, as well as capacity increase. In order to rationalise, and increase efficiency of Serbian lignite mines, it is necessary to focus the activities on major issues shown within the triangle of energy policy objectives (security of supply, competi-tive prices and environmental protection). Production process optimisation singled out several special programs. Equipment revi-talization and modernization is necessary taking into account that majority of the currently operated machinery has a life up to 25 years. Production process automation would enable high level of technical operation in the field of open cast mines management. Lack of coal quality uniformity is the permanent problem resulting by great amounts of coal reserves to be used uneconomically. Planning and training at all levels and finally cooperative software for business procedures and work order management. The measures suggested are a key precondition for maintaining competitive position of lignite production on international level.     

A concept of the establishing the computer supported information-management system at the “Drmno” open pit mine,Coal Basin Kostolac

With the aim of the modernization of the coal exploitation, a research study on establishing the computer supported information-management system at the open pit mine “Drmno”, within the Coal Basin Kostolac was completed. The study gives a review of the concept, logical and physical topology, communicational ambience, architecture, course of further activities, development dynamics, and framework of expenses and benefits of computer supported information-management system construction. The paper presents a short review of the real system, goals, basic demands, concept and topology of the information-management system establishment. A development strategy and effects expected upon the establishment of the information-management system are presented at the end of paper. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 3, pp. 102–109, May–June, 2008.     

Bioaccessibility of uranium in soil samples from port hope, ontario, Canada

Adequate assessment of human health risk of uranium contamination at hazardous waste sites, which is an important step in determining the cleanup strategy, is based on bioavailability data. Bioavailability of uranium from contaminated soil has not been properly determined yet. Bioaccessibility is an in vitro conservative estimate of bioavailability and is thus frequently used for site-specific risk assessment. Bioaccessibility of uranium was measured in 33 soil samples from the Port Hope area in Ontario, Canada, by the physiologically based extraction test (PBET). Higher bioaccessibility values in the gastric plus intestinal phase, 48.4% ± 16.8%, than in the gastric phase, 20.8% ± 11.7%, are very probably the result of more efficient extraction of uranium from soil by intestinal fluid rich in carbonate ions. The observed variability of measured bioaccessibility values is discussed in light of the results of scanning electron microscope examination of the soil samples. Uranium bioaccessibility values in both gastric (acidic) and gastric plus intestinal (neutral) phases are higher in soil samples with smaller uranium-bearing particles and lower in samples where the uranium-bearing particles are larger. We postulate that the most important reason for variability of measured bioaccessibility values in Port Hope soil samples may be the difference in particle size of uranium-bearing particles.