• An experimental study on energy generation from photovoltaic-thermal hybrid systems

    pg(s) 76-78

    Solar energy is one of the leading renewable energy sources because of its great potential, affordability of the individual system prices, zero emission and no noise emission. 21st century will be based on renewable energy sources, with strict environmental measures, primary energy use will mainly consist of a combination of (different) clean energy sources among which solar energy will play a leading role. Two technologies for harnessing the energy of the sun are photovoltaic cells (PV) and solar collectors. Photovoltaic cells (PV) exploit the visible part of the spectrum while solar collectors use the infrared part. Combining these two technologies into one provides a system that produces electricity and heat at the same time using all parts of the solar spectrum. These systems are known as photovoltaic thermal systems or PV/T. This paper presents the description of these systems and methods of application. Among this, this paper gives description of experimental PV/T installation at Faculty of Mechanical Engineering in Banja Luka.

  • Concept of parametric design and fast 3D printing of individual shoes

    pg(s) 72-75

    A personalized approach to printing individual shoes is possible due to the availability of laser scanning of the feet and professional interpretation of the results. Based on preliminary diagnostics of the condition of the musculoskeletal system in areas of high pressure in the feet, it is possible to identify problems associated with pain in the joints of the lower extremities and lumbosacral, abnormalities and asymmetries of their structure. It is also possible to timely relieve ankle, knee, femoral joints, lumbosacral spine, correct posture and gait, reduce joint pain, prevent surgery on joints of the lower extremities and lumbosacral spine, monitor the dynamics of changes in the rehabilitation period.
    The task of effective prevention and early diagnosis of problems of the musculoskeletal system can be solved with the targeted popularization of individual shoes and orthopedic insoles among the population, as well as its accessibility thanks to additive technologies, databases of parametric digital models, an established production and technological cycle and a flexible client-oriented service , including protocols for remote and virtual interaction between production and the end user.
    However, shoes printed on a 3-D printer, so far, are not attractive to consumers or manufacturers. Mass production of shoes is still much faster and cheaper, although initially it was assumed that the introduction of additive technologies will significantly reduce the cost and time costs, but so far this has not happened for several reasons. In our country, there is a shortage of specialists in digital technologies, 3Dmodeling and printing. In addition, as elsewhere in the world, equipment for fast 3D printing has a very high cost and only giants such as Adidas or Nike can create real production of printed products. However, it is a matter of time. The area of additive technologies is attracting more and more medium and small firms, individual designers, because 3D printing allows you to achieve unexpected and revolutionary results, as well as provide customized solutions at an affordable price.


    pg(s) 29-32

    Technology and innovations have powered the evolution of Industry4.0, the fourth industrial revolution.
    State-of-the-art technologies such as the Internet of Things (IoT), cloud computing (CC), big data analytics (BDA), and artificial intelligence (AI) – all part of Industry4.0, have greatly stimulated the building industry. Digital Тwin is a significant enabler for Industry 4.0 initiatives. Within Industry 4.0, the amount of digital product information generated and collected over the entire lifecycle has been growing.
    Although digital twins have been around for several decades, the rapid rise of the internet of things (IoT) is that they have become more widely considered as a tool of the future. Digital twins are getting attention because they also integrate things like artificial intelligence (AI) and machine learning (ML) to bring data, algorithms, and context together
    A ―digital twin‖—or digital replica of a physical entity—can target building industry in several sub-areas:
    – Facility management
    – Product Lifecycle Management
    – Smart Buildings
    – Smart energy
    All these areas are one giant step further by creating a Digital Twin — a virtual representation of real-world buildings that can be viewed and scrutinized in minute detail. This research describes business cases and best practices in design of IoT Solutions for building industry, powered by Digital Twins. A reference architecture and prototypes which demonstrate application of Digital Twins in Smart are created as a result of this study .This research is technology agnostic, but prototypes of sample solutions are considered in the context of Microsoft Azure (Azure solutions, covering Azure Digital Twins Service and Azure IoT Stack.)


    pg(s) 27-28

    During the last two decades the Heating Ventilation Air Condition (HVAC) systems have been used to enable heating, cooling and ventilation of buildings with the primary aim of meeting the requirements of thermal comfort and indoor air quality. In this research work, energy consumption in buildings has been analysed by using Hourly Analysis Program (HAP) software. The object of our research work was focused in the Polytechnic University of Tirana. Mathematical models of thermal calculations have been based on the international standard ISO 13790: 2008 on energy use and thermal performance of buildings.


    pg(s) 23-26

    This paper covers the advanced Additive Manufacturing (AM) techniques used to fabricate prostethic and orthotic devices. It reviews the available literature and summarizes the advances in medicine, computing and engineering that have led to the development of currently available prostheses. Some of the open-source bionic hands and other available prosthesis are shown, as well as the technologies and materials which are used to manufacture the parts. Since prototyping, combined with the possibility for easy maintenance and repair, is very attractive for prosthesis design, as a conclusion we summarize and discuss some of the key areas that could lead to improvements in bionic limb functionality and use.


    pg(s) 302-305

    In the last few years, application of selenium has increased significantly due to its unique possibilities to acts as an antioxidant and as an anticancer reagent in human body. Due to this, selenium is one of the most important chemical elements for human health. Recently, selenium usage in microelectronics was significantly increased as semiconductors with characteristic electronic properties. The selenium is the least abundant element in earth crust, but as the application fields of selenium are widely opened, the needs of this element are larger. This opens new views in the field of improving existing and developing new technologies for extraction of selenium.
    In this work, a new technology for extraction of selenium from natural resources was developed, by combining the advantages and removing the disadvantages and weaknesses of the existing technologies. The sediments near mineral water springs and used water filters with content from 0.0656 to 0.9291 % wt. of Se were used as mineral selenium resources. Also, the plants such as Astralagus bisulcatus and Stanleya pinnata with content of Se around 100 mg·kg–1 biomass were used as a plant resources. The technology presented in this work is a combination of pyrometallurgical and chemical methods in order to obtain intermediates reach with selenium, and further chemical and electrochemical extraction of selenium from these intermediates was done. The analyzes were performed using Inductively Coupled Plasma – Atomic Emission Spectrometry (ICP-AES). The results have shown that from mineral resources can be extracted pure red technical selenium with analytical grade up to 48.3 % of Se. From the plant resources can be obtained enriched selenium intermediates with analytical grade from 1.367 to 1.604 % wt. of Se which are potential material for medicine applications.


    pg(s) 297-301

    The main scope of this paper is to fully integrate simulation from open source CFD software with the Matlab App Designer program. The OpenFOAM-Matlab CFD interface allows one to conveniently setup fully turbulent incompressible Reynolds Averaged Navier-Stokes (RANS) CFD case all within an easy to use graphical user interface (GUI). Highlighting built-in CAD tools to create geometry (STL) for automatic mesh generation to OpenFOAM case file as well as a solution with post-processing and visualization with ParaView. Also, the cross-platform OpenFOAM CFD interface for MATLAB should allow the user to rapidly design the spiral casing in an engineering manner as an illustrative platform and coordinator between the inputs chosen by the user and the results which are displayed after calculations. Furthermore, the GUI should be a very flexible and user-friendly platform for spiral casing design according to the efficiency and static pressure recovery coefficient as well.


    pg(s) 293-296

    An important requirement of digital electronic devices is the comprehensive provision of electromagnetic compatibility. In particular, it is necessary for electrical, electronic and radio equipment to ensure a sufficient level of noise immunity when exposed to microsecond pulse interference. The international standard IEC 61000-4-5 regulates the testing of equipment for microsecond impulse noise. Carrying out such physical tests is quite complicated and requires expensive equipment. The article proposes computer simulation of testing electronic devices in accordance with the requirements of IEC 61000-4-5.


    pg(s) 290-292

    All production processes in the world are implementing Industry 4.0 by using the basic technologies such as robotics & automation, intelligent sensors, 3D printers, radio frequency identification – RFID, cloud computing, Internet of Things and Internet of Services. Implementation of Industry 4.0 in all production processes is not possible without the use of both industrial and service robots, their development and implementation. In addition, there are other technologies on which the fourth industrial revolution is based that will provide us with intelligent devices, intelligent production processes, intelligent logistics in production processes, i.e. intelligent factories. The Cyber-Physical Systems (CPS) in the global environment provide machine networking in production processes and logistics systems. This paper provides an example of the use of service robots and their role in solving smart transport in production processes.

  • Experimental study on energy consumption in the plasticizing unit of the injection molding machine

    pg(s) 241-243

    Injection moulding is a widespread method of polymer processing. The annual, global energy consumption for injection moulding is comparable to the annual energy production of different European countries. The most energy-consuming stage of the injection moulding is the plasticization process, which needs the energy mainly for the rotational and reciprocating screw motion as well as the heating of the barrel. Both issues were examined by changing various parameters of the injection moulding process, measuring the process characteristics and calculating the corresponding values of SEC (specific energy consumption). Various thermoplastic polymers were examined. It was found that the optimal conditions from the energy consumption point of view is low value of rotational velocity of the screw. Changes of back pressure do not affect the energy consumption of the plasticizing system of the injection moulding machine. Furthermore, an increase of the SEC value with increasing barrel temperature was shown. It was ca. 15% for the average barrel temperature rise of 20°C.

  • New concepts for the active grooved-feed section extruder

    pg(s) 237-240

    The article discusses the current state of knowledge about the active grooved feed section of an extruder and presents its new constructional solutions. The grooved feed has been known for thirty-five years; there are not so many constructional solutions, and most of them come from the United States and Poland. Unlike the passive grooved feed section, the active grooved feed section has not, as yet, been used in industrial processing machines.

  • Review of unconventional barrel designs of plasticizing systems used in single-screw extruders

    pg(s) 232-236

    Extrusion is one of the most important processes in polymer processing technology, just next to injection molding. The first extruder was invented and patented in 1879 by Matthew Gray, which used Archimedes screw in its design [1]. Since that time, constantly work on improving the work of extruders was carried out, which are implemented in two different ways, technological or constructional [2, 3, 4]. The constructional method involves both the modification of the screw design and the entire barrels of the plasticizing system. Evidence of the relevance of this issue may be the number of patents describing the classic and unconventional constructions of extruders [4]. The aim of the following work is to conduct a review of the contemporary construction solutions of the plasticizing systems barrels, whose applications were intended to improve the efficiency and effectiveness of the extrusion process. One of the most interesting solutions is the kinematic activation of the barrel wall in the metering zone by introducing a rotary sleeve in a plasticizing system whose rotational speed and direction can be freely modified.