Dobrica Milovanovic

Improvement of algorithm for numerical crack modelling

For numerical simulation of crack modelling in fracture mechanics the eXtended finite element method (Xfem) has been recently accepted as a new powerful and efficiency methodology. In the paper we present the details of implementation of the Xfem algorithm in our in-house finite elements based software. Also, in this study, we investigated the impact of the node enrichment variations on results of the developed numerical procedure. In this study, objective was to examine the properties of standard Xfem algorithm without using of Near Tip enriching functions in order to create possibilities for future application Xfem in the zone of plasticity. In order to evaluate the computational accuracy, numerical results for the Stress Intensity Factors are compared with both theoretical and conventional finite element data. Obtained numerical results have shown a good agreement with the benchmark solutions. For calculation of the Stress Intensity Factors (SIF), we used the J-Equivalent Domain Integral (J-EDI) Method. Computational geometry issues, associated with the representation of the crack and the enrichment of the finite element approximation, are discussed in detail.

Spool valve leakage behaviour

A four-way axial spool servovalve has such a design that flows through its restrictions can be presented by means of a hydraulic bridge. The characteristics analytically describe the fluid flow through spool orifices in the most of working regimes. The exceptions are regimes around the null characterised by an overlap existence when internal leakages dominate. Several mathematical models for the calculation of the internal leakage flows are presented in this paper including theoretical model worked out by authors. Modelling results are compared with appropriate experimental.

Energy efficiency in buildings, industry and transportation

This paper reviews the literature concerning the energy saving and outlines the importance of energy efficiency, particularly in three the most important areas: buildings, industry and transportation. Improving energy efficiency plays a crucial role in minimizing the societal and environmental impacts of economic growth and offers a powerful tool for achieving sustainable development by reducing the need for investment in new infrastructure, by cutting fuel costs, and by increasing competitiveness for businesses and welfare for consumers. It creates environmental benefits through reduced emissions of greenhouse gases and local air pollutants. It can offer social benefits in the form of increased energy security (through reduced dependence on fossil fuels, particularly when imported) and better energy services.

Energy Efficiency, Environmental Protection and Sustainable Development in Kragujevac (Serbia)

This paper presents a methodology development and the results achieved in the process of establishing energy management system in the City of Kragujevac (Serbia) and in its public services. The paper is an overview of influential factors in the field of energy management, analyzing their impact on raising the energy efficiency of individual utility service and the city of Kragujevac, as a whole. The paper also presents the most interesting scientific and research projects realized in the cooperation of several actors which were coordinated by Regional Euro Energy Efficiency Center Kragujevac. The municipal companies together with the city administration are the direct beneficiaries of the results realized in the following areas: ‐ Development of energy management in municipalities and the establishment of energy planning at the local level; ‐ Improvement of municipal services by applying energy efficiency measures in public enterprises: ‐ “Energetika” (heating), ‐ “Cistoca” (communal waste management), ‐ “Vodovod i kanalizacija” (water and waste water management); Promotion of ideas and projects realized in the field of energy management, environmental protection and sustainable development at the Festival of energy efficiency (starting from this year) held during the April.