COLLECTIONS

Documents published in Scipedia

• Software for deep-well designing

  D. Tomić, N. Banjac, D. Brkić

  Istraživanje i Projektovanje za Privredu (2005). Journal of Applied Engineering Science 3 (10), 21-27, 2005

  
  

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• Are fossil fuels the main cause of today's global warming?

  D. Brkić

  Facta Universitatis-series: Working and Living Environmental Protection (2009). Facta Universitatis-series: Working and Living Environmental Protection 6 (1 …, 2009

  
  

  Abstract

  Gas will increasingly be seen as the fossil fuel of choice, especially when considering environmental impacts. Natural gas is the chance for Serbia for sustainable development and with its intensive consumption in the XXI century to conciliate the 4Es (Energy, Economy, Efficiency and Environment). In this paper we will compare the impact of different fossil fuels used for domestic heating with a special emphasis on natural gas. Some other causes of climate changes will be also discussed such as the Milanković astronomical cycles. These factors will be compared with climate changes caused by the consumption of fossil fuels.

  Abstract
  Gas will increasingly be seen as the fossil fuel of choice, especially when considering environmental impacts. Natural gas is the chance for Serbia for sustainable development [...]

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• Natural gas heating in Serbian settlements according to urbanity parameters

  D. Brkić

  Facta universitatis-series: Architecture and Civil Engineering (2008). Facta universitatis-series: Architecture and Civil Engineering 6 (1), 139-153, 2008

  
  

  Abstract

  Natural gas can be directly used for heating of flats by gas distribution system. Indirectly, heating power plant can disburse natural gas and deliver hot water or steam for heating of flats. Decision of optimal way for gas heating usage is done based on spatial disposal of building, number and size of buildings in settlement, etc. Optimal solution, between gas distribution and district heating system (local or district heating by natural gas), can be done according to methodology (model approach) shown in this paper. According to variety of Serbian settlements (in density, size and layout of buildings) model which has ability to represent their different characteristics is formed. This model could be simple and useful tool for initial decision about energy supply system.

  Abstract
  Natural gas can be directly used for heating of flats by gas distribution system. Indirectly, heating power plant can disburse natural gas and deliver hot water or steam for [...]

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• Natural gas distribution and domestic usage efficiency

  D. Brkić

  (2010). University of Begrade, Department of Petroleum and Natural Gas Engineering, Belgrade, Serbia

  
  

  Abstract
  http://nardus.mpn.gov.rs/123456789/2654

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• Gas distribution network topology problem

  D. Brkić

  Mathematica Balkanica (2012). 26 (3-4), 277-284

  
  

  Abstract

  Problem of gas fow in looped network is nonlinear problem and these kind of problems have to be solved using some kind of iterative procedure. For the pipeline network, two topology matrices can be written; i.e. loop matrix and node matrix. The node matrix is related to the first Kirchho 's law while the loop matrix is related to second Kirchho 's law. Here will be shown effcient method in which both matrices, i.e. the node and the loop matrix are united in one coherent procedure for solution of looped gas pipeline problem.

  Abstract
  Problem of gas fow in looped network is nonlinear problem and these kind of problems have to be solved using some kind of iterative procedure. For the pipeline network, two [...]

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• Lambert W function in hydraulic problems

  D. Brkić

  Mathematica Balkanica (2012). 26 (3-4), 285-292

  
  

  Abstract

  Darcy’s flow friction factor is expressed in implicit form in some of the relations such as Colebrook’s and have to be solved by iteration procedure because the unknown friction factor appears on both sides of the equation. Lambert W function is implicitly elementary but is not, itself, an elementary function. Implicit form of the Lambert W function allows us to transform other implicit functions in explicit form without any kind of approximations or simplifications involved. But unfortunately, the Lambert W function itself cannot be solved easily without approximation. Two original transformations in explicit form of Colebrook’s relation using Lambert W function will also be shown. Here will be shown efficient procedure for approximate solutions of the transformed relations.

  Abstract
  Darcy’s flow friction factor is expressed in implicit form in some of the relations such as Colebrook’s and have to be solved by iteration procedure because the [...]

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• Intelligent flow friction estimation

  D. Brkić, Ž. Ćojbašić

  Computational Intelligence and Neuroscience (2016). 2016, article 5242596

  
  

  Abstract

  Nowadays, the Colebrook equation is used as a mostly accepted relation for the calculation of fluid flow friction factor. However, the Colebrook equation is implicit with respect to the friction factor (). In the present study, a noniterative approach using Artificial Neural Network (ANN) was developed to calculate the friction factor. To configure the ANN model, the input parameters of the Reynolds Number (Re) and the relative roughness of pipe () were transformed to logarithmic scales. The 90,000 sets of data were fed to the ANN model involving three layers: input, hidden, and output layers with, 2, 50, and 1 neurons, respectively. This configuration was capable of predicting the values of friction factor in the Colebrook equation for any given values of the Reynolds number (Re) and the relative roughness () ranging between 5000 and 108 and between 10−7 and 0.1, respectively. The proposed ANN demonstrates the relative error up to 0.07% which had the high accuracy compared with the vast majority of the precise explicit approximations of the Colebrook equation.

  Abstract
  Nowadays, the Colebrook equation is used as a mostly accepted relation for the calculation of fluid flow friction factor. However, the Colebrook equation is implicit with [...]

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• A note on explicit approximations to Colebrook’s friction factor in rough pipes under highly turbulent cases

  D. Brkić

  International Journal of Heat and Mass Transfer (2016). 93, 513-515

  
  

  Abstract

  New explicit approximations to the implicitly given Colebrook equation for flow friction factor are given. They are with improved accuracy compared with the one recently published [Shaikh et al.: Int. J. Heat Mass Tran. 88 (2015) 538–543]. The new approximations are highly accurate only in rough pipes under fully developed turbulent cases of flow.

  Abstract
  New explicit approximations to the implicitly given Colebrook equation for flow friction factor are given. They are with improved accuracy compared with the one recently published [...]

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• Spreadsheet-based pipe networks analysis for teaching and learning purpose

  D. Brkić

  Spreadsheets in Education (eJSiE) (2016). 9 (2), article 4646

  
  

  Abstract

  An example of hydraulic design project for teaching purpose is presented. Students’ task is to develop a looped distribution network for water (i.e. to determinate node consumptions, disposal of pipes, and finally to calculate flow rates in the network’s pipes and their optimal diameters). This can be accomplished by using the original Hardy Cross method, the improved Hardy Cross method, the node-loop method, etc. For the improved Hardy Cross method and the node-loop method, use of matrix calculation is mandatory. Because the analysis of water distribution networks is an essential component of civil engineering water resources curricula, the adequate technique better than the hand-oriented one is desired in order to increase students’ understanding of this kind of engineering systems and of relevant design issues in more concise and effective way. The described use of spreadsheet solvers is more than suitable for the purpose, especially knowing that spreadsheet solvers are much more matrix friendly compared with the hand-orientated calculation. Although matrix calculation is not mandatory for the original Hardy Cross method, even in that case it is preferred for better understanding of the problem. The application of commonly available spreadsheet software (Microsoft Excel) including two real classroom tasks is presented.

  Abstract
  An example of hydraulic design project for teaching purpose is presented. Students’ task is to develop a looped distribution network for water (i.e. to determinate node [...]

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• Study on the impacts of possible amendments to the ATEX, the Machinery, and the Pressure Equipment Directives with respect to equipment intended for use in the offshore oil and …

  A. Aznárez, D. Brkić, S. Contini, M. Christou, S. Tarantola

  (2016). Publications Office of the European Union

  
  

  Abstract

  The purpose of this study is to provide the Commission with the information necessary for the assessment of the economic, social, and environmental impacts of a possible extension of the scope of the EU product safety legislation (ATEX Directive 2014/34/EU, Pressure Equipment Directive 2014/68/EU and Machinery Directive 2006/42/EC) with respect to equipment intended for the use in the offshore oil and gas industry. Whereas equipment on fixed units is in the scope of these three Directives, mobile offshore units and equipment installed on them are currently in general excluded. In addition the Pressure Equipment Directive excludes also well-control equipment. The study investigates whether there are safety issues which could be addressed by extending the scope of the Directives and what would be the impacts of such an extension. Title Study on the impacts of possible amendments to the ATEX, the Machinery, and the Pressure Equipment Directive with respect to equipment intended for use in the offshore oil and gas industry.

  Abstract
  The purpose of this study is to provide the Commission with the information necessary for the assessment of the economic, social, and environmental impacts of a possible extension [...]

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Articles (Documents not available in Scipedia)

• Discussion of “Friction modeling of flood flow simulations” by Vasilis Bellos, Ioannis Nalbantis, and George Tsakiris

  D Brkić, P Praks

  Journal of Hydraulic Engineering 146 (5), article 07020007, 2020

• Discussion of “Approximate analytical solutions for the Colebrook equation” by Ali R. Vatankhah

  D Brkić, P Praks

  Journal of Hydraulic Engineering 146 (2), article 07019011, 2020

• A possible publishing model profitable for authors

  D Brkić

  GRIN Verlag, 2019

• Correction: Brkić, D., and Praks, P. Accurate and efficient explicit approximations of the Colebrook flow friction equation based on the Wright ω-function. Mathematics 2019, 7, 34

  D Brkić, P Praks

  Mathematics 7 (10), article 951, 2019

• Discussion of “Economics and statistical evaluations of using Microsoft Excel Solver in pipe network analysis”

  D Brkić

  Journal of Pipeline Systems Engineering and Practice 9 (3), article 07018002, 2018

• Discussion of “Exact analytical solutions of the Colebrook-White equation”

  D Brkić

  Journal of Hydraulic Engineering ASCE 143 (9), article 07017007, 2017

• Discussion of “Gene expression programming analysis of implicit Colebrook–White equation in turbulent flow friction factor calculation”

  D Brkić

  Journal of Petroleum Science and Engineering 124, 399-401, 2014

• Discussion of “Method to cope with zero flows in Newton solvers for water distribution systems”

  D Brkić

  Journal of Hydraulic Engineering 140 (4), 456-459, 2014

• Very accurate explicit approximations for calculation of the Colebrook friction factor

  Ž Ćojbašić, D Brkić

  International Journal of Mechanical Sciences 67, 10-13, 2013

• Discussion of “Sustainable electric power system: Is it possible? Case study: Croatia”

  D Brkić

  Journal of Energy Engineering 138 (3), 163-164, 2012

• Discussion of “Jacobian matrix for solving water distribution system equations with the Darcy-Weisbach head-loss model”

  D Brkić

  Journal of Hydraulic Engineering 138 (11), 1000-1001, 2012

• Discussion of “Water distribution system analysis: Newton-Raphson method revisited”

  D Brkić

  Journal of Hydraulic Engineering 138 (9), 822-824, 2012

• Can pipes be actually really that smooth?

  D Brkić

  International Journal of Refrigeration 35 (1), 209-215, 2012

• Comparison of the Lambert W‐function based solutions to the Colebrook equation

  D Brkić

  Engineering Computations, 2012

• Determining friction factors in turbulent pipe flow

  D Brkić

  Chemical Engineering N.Y. 119 (3), 34-39, 2012

• Comments on "Experimental study of the pressure drop in the cathode side of air-forced open-cathode proton exchange membrane fuel cells"

  D Brkić

  International Journal of Hydrogen Energy 37 (14), 10963-10964, 2012

• Discussion of “Classroom activities to illustrate concepts of Darcy’s Law and hydraulic conductivity”

  D Brkić, V Mitrović

  Journal of Professional Issues in Engineering Education and Practice 137 (1 …, 2011

• Iterative methods for looped network pipeline calculation

  D Brkić

  Water Resources Management 25 (12), 2951-2987, 2011

• An explicit approximation of Colebrook's equation for fluid flow friction factor

  D Brkić

  Petroleum Science and Technology 29 (15), 1596-1602, 2011

• New explicit correlations for turbulent flow friction factor

  D Brkić

  Nuclear Engineering and Design 241 (9), 4055-4059, 2011

• Review of explicit approximations to the Colebrook relation for flow friction

  D Brkić

  Journal of Petroleum Science and Engineering 77 (1), 34-48, 2011

• Comments on “Settling velocities of particulate systems 15: Velocities in turbulent Newtonian flows”

  D Brkić

  International Journal of Mineral Processing 92 (3-4), 201-202, 2009

• Serbian gas sector in the spotlight of oil and gas agreement with Russia

  D Brkić

  Energy Policy 37 (5), 1925-1938, 2009

• An improvement of Hardy Cross method applied on looped spatial natural gas distribution networks

  D Brkić

  Applied Energy 86 (7-8), 1290-1300, 2009

• Serbian, Russian pipeline accord enhances European gas security

  D Brkić

  Oil & Gas Journal 106 (48), 52-54, 2008

• Systematic approach to natural gas usage for domestic heating in urban areas

  D Brkić, TI Tanasković

  Energy 33 (12), 1738-1753, 2008

• Prirodni gas kao gorivo za grejanje

  D Brkić

  Zadužbina Andrejević, 2006

• Određivanje graničnih parametara upotrebe prirodnog gasa u Beogradu

  D Brkić

  University of Belgrade, Faculty of Mining and Geological Engineering, 2005