• Use of oriented strandboard in construction industry

    pg(s) 93-96

    In recent years, 3D printing has gradually appeared in people’s field of vision. The addition of wood in thermoplastics improve their some mechanical properties such as tensile and bending modulus without affecting its biodegradability. The decrease in the cost of filaments may enlarge the utilization of biodegradable filaments after the disposal in near future. Small-scale elements used in furniture production, such as connector fittings or fasteners for shelves, may give functional and structural properties without significant investment. 3D-printed connections are suitable when the the production complex shaped connectors and quick disassembly are required, to reduce the product’s weight and price

  • Studing the temperature microclimate in beehives made out of defferent materials

    pg(s) 91-92

    The use of clay as a structural material has been known for centuries. The authors set the task of studying the applicability of clay as a constructive material in the production of beehives. The study aims to make a comparative analysis of temperature conditions in different types and identical in construction beehives by comparing the indicator for ceramic and wooden hives. For the purpose were used three 10-frame hives type “Dadan-Blat” – two ceramic (one made entirely of marl clay, and the other – with increased kaolin content, both ceramic tiles are with high cavity) and one wooden (pine). Measurements of the air temperature and the temperature inside the hives were made for one month. From the obtained results it is established that for the studied beehives, the ceramic hive with high kaolin content has the best thermal insulation properties.

  • Application of submodeling in strength analysis of horizontal tank for storage of petroleum products

    pg(s) 87-90

    This paper shows the approach of submodeling in finite element analysis in process of designing the horizontal tank for storing petroleum products. Those kinds of tanks are made at exact standards or slightly altered by customers’ demands. Before the numerical analysis of the tank, the tank standards are described as well as numerical analysis. In the paper, the methods which will be used in obtaining solutions by finite element method were described. 3D finite elements have been used for numerical analysis. After getting the results of full tank model meshed with 3D tetrahedral final elements, the technique of submodeling has been used to achieve more accurate results in critical locations of the tank. In the final aspect, result analysis was conducted, where the results were confirmed so that the tank complies with the standard and meets all the criteria given to the designer.

  • Comparison of different position controllers implemented with a Beckhoff controller and TwinCAT 3 software

    pg(s) 83-86

    Achieving the required dynamics and accuracy of movement of electromechanical linear axes is one of the basic tasks in the field of modern production machines and devices. In addition to a sufficiently powerful electric motor, e.g. electric servomotor, the appropriate controller and control concept also play a key role. As the top performance of the electromechanical axle controller is still a key feature of efficient and quality production, this topic is discussed in this paper.
    At the forefront of the paper are the development and implementation of various position controllers developed in the Beckhoff TwinCAT 3 environment. In addition to the classic PID controller already available in the Beckhoff software, a special PID controller has been developed in the Matlab / Simulink environment, as well as a Fuzzy controller and a Feedforward control strategy. For all mentioned types of controllers, the basic characteristics, design approach and parameterization of the controllers are presented. The efficiency of individual position controllers on an industrial-type electromechanical linear axis, driven by an electric servomotor, was tested experimentally and the results are compared.
    The efficiency of these closed loop controllers was also tested in terms of robustness and ability to adapt to changes in the control loop, where a different load of moving mass was used as a characteristic change in the control loop.

  • Innovative method for repair of reinforced concrete water facilities by “wet” shotcreting

    pg(s) 79-82

    The report presents the different stages of development and implementation of two similar innovative technical solutions for repair and restoration of defected reinforced-concrete constructions of existing swimming pool and artificial lake using the methods of “wet” shotcreting. In the first case, the object of renovation is a seriously defected outdoor mineral pool of a prestigious hotel in the town of Hissarya. Given the significant leaks of water from the pool in the surrounding area over the years, a specialized technical inspection was initially conducted to determine the causes of defects in the main load-bearing monolithic steel-reinforced concrete construction – walls and bottom slab. An innovative technical solution has been proposed to restore the operational suitability of the pool, based on the possibility of using the existing load-bearing structure as external formwork for a new built-in load-bearing structure of the facility. The proposed solution envisages jointless thickening of the existing walls through additional reinforcement and concrete laying of new high-tech sprayed concrete. The bottom of the pool is being renovated by additional new layer of a hybrid fiber-reinforced jointless concrete slab and machine powerfloated of the finishing surface. A composition of high-tech concrete with the participation of an internal crystallization chemical admixture and shrinkage-compensating one is proposed. A similar solution has been applied for the repair and restoration of the walls and bottom of an artificial lake in West Park, Sofia. Implementation of the project creates a unique art vision of the lake, the rock garden and the surrounding park space. This pilot implementation creates objective preconditions for expanding the range of innovative concrete structural systems, which, in addition to specific functions, are also applicable as opportunities for aestheticizing the urban and park environment.

  • Friction stir welding of dissimilar materials based on aluminum alloys

    pg(s) 76-78

    The paper focuses on the application of friction stir welding (FSW) technology for welding of unequal materials based on aluminum alloys. Joints were made from AW 5083 and AW 6082 materials using FSW technology at different weld speed values. The joints were analyzed metallographically, the hardness of the materials was tested across the cross section of the joint and the strength of the joint was tested by destructive static tensile test. At the lowest weld speed, the materials were not perfectly mixed, there was a macroscopically visible gap at the joint location, which was reflected in the lack of joint strength. At the medium and highest weld speed values, a joint with mechanical properties comparable to those of the base material was formed. Metallographically, the bond between the materials was free of any internal defects.

  • Development of an environmentally friendly commercial kitchen cooker using hydrogen as fuel

    pg(s) 46-48

    Commercial kitchen cookers are widely used in various capacities and fuels (natural gas, LPG, etc.). Depending on the decrease in fossil resources and the increase in energy needs, several researches in alternative fuels have been accelerated. Especially in recent years, R&D studies and investments in renewable and environmentally friendly energy sources (solar, wind, biomass etc.) have increased. In line with the EU’s Renewable Energy Directive (Directive 2018/2001/EU), it is aimed to use at least 32% renewable energy sources by 2030. Significant R&D gains have been achieved with the cooperation of industry-university in order to use hydrogen as clean energy as an environmentally friendly alternative energy source for commercial kitchens. In this work, we developed an environmentally friendly commercial kitchen cooker prototype using hydrogen with a uniquely designed burner has been achieved. Results show that using hydrogen in commercial kitchens is promising if hydrogen safety is locally possible.

  • Innovative technologies for the production of high-oxide corundum and boron carbide ceramics

    pg(s) 40-45

    In this publication, the authors present an in-depth justification on the technology for the production of high-oxide ceramics. Indepth research on international markets on the supply and use of raw materials is presented. The various design developments related to the ways of pressing products are described. The physico-mechanical parameters of the synthesized corundum and boron-ceramic ceramics were also studied.

  • Disinfection and dye adsorption efficiency of functionalised nonwoven adsorbent for household textile laundering

    pg(s) 36-39

    The efficiency of an adsorbent has been investigated for the removal of released textile dyes and micro-organisms during household textile laundering. The results show that laundering with the addition of the striped adsorbent and IEC A* detergent reduced the higher log step reduction of Sa (more than 4 log steps) compared to laundering without detergent (2.62 log step reduction), or laundering in a blind bath (1.61 log step reduction). The sorption efficiency of the functionalised nonwoven adsorbent is limited, capable of adsorption of a maximum of 0.1 g/L of reactive dye from the washing bath. Laundering in a bath of 20 °C, with the addition of a striped textile adsorbent or in combination with detergent IEC A*, does not prevent biocontamination of the washing bath and textile load.

  • Deacidification in the protection of written collections

    pg(s) 32-35

    The aim of this article is to emphasize the importance and significance of deacidification as an important and basic conservation process in the preservation of written paper collections. This is a process in which buffer substances are introduced by processing the paper collections, which maintain the pH of the paper within optimal limits for storage. At the same time, they eliminate the possibility of oxidation-reduction processes during future long-term storage. Relatively few chemical reagents are known in practice that have the ability to neutralize acids in paper documents. These are sodium, barium, magnesium, some saponins, amines, borates, phosphates, some polymers of alkaline salts of organic acids. The development of deacidification as a conservation process has been followed and it is concluded that it does not develop rapidly, but is accompanied by too much hesitation and caution. Mass deacidification processes are expensive and cannot provide the desired result and lead to the introduction of essentially different methods. Along with the advantages and disadvantages of each method, the quantitative and qualitative condition of the collections, the institutions find it difficult to select the most appropriate one to be applied to their collections. Bookkeeper, PaperSave Swiss and Bückeburg are listed as effective deacidification methods. These three methods are highly valued as applicable to mass deacidification of documents, in terms of potential for innovation, improvement of mechanical strength and existence, pH and alkaline reserve, cost and risk assessment.

  • Stakeholder analysis for development of knowledge management system in micro- and nanoelectronics

    pg(s) 30-31

    Knowledge management relates to the vast majority of business-processes at enterprises in knowledge-intensive sectors, such as nanoindustry. In particular, all stages of the new products’ creation, i.e., research, development, launch of the production line, manufacturing and operation, are associated with the new knowledge generation. However, one can find numerous inefficiencies in the existing business-processes due to a lack of communication and poor data handling. Although the financial consequences of ignoring these problems are significant for the enterprises, the absence of step-by-step solution plan and human resource overload make it necessary to look for different ways to solve the issues related to this topic. In order to successfully solve the detected problems and thus ensure support for the further development of the knowledge management system, five key directions were formulated based on the interviews with stakeholders.

  • Investigation of rubber granules used in artificial turf systems with FTIR spectroscopy with ATR system and DSC

    pg(s) 171-173

    The purpose of this study was to investigate the structure of recycled tires which are used in artificial turf/ grass as infi ll materials. One of the most important issues, especially in Albania is proving that these materials are recycled. In this paper it is presented the FTR with ATR system methods analyses. That will provide info regarding the combining material in rubber granules, for the investigation of their structure, it was used the spectroscopy method, with vibration infrared and Fourier FTIR transformation equipped with ATR system, a method which enables analysis of samples of thick surface, without any prior preparation. The scanning of samples was done with wavelength from 4000-400 cm-1. At the same time was possible to see the changes in the micro-structure of the tires by using the Differential scanning calorimetry (DSC) analyses.