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Sustainable economy of non renewable resources and conflict with environment
Get PDFMining is one of the technology processes which significantly affect the environment. Contemporary science is
often focused on renewable resources, but non renewable resources and their mining are also present and deserve more
intense research, due to its complex role in the economy. On the other point of view, non renewable resources as mining
products are necessary to maintain and improve the life quality level. This conflict is not sustainable in long term
perspective. From the aspect of sustainable development the primary task is to ensure the development right for future
generations. It means that intensive level of interdisciplinary research is necessary to provide initial conditions
(available reserve of ore) and utilization dynamic of mineral resources. This paper analyzes some aspects of
correlation between sustainable development and mining. Mathematical model that describes the mentioned ideas is
developed in this manuscript, including the conflict of economic goals, principles of environmental protection and
sustainable development
Flexibility of power generation and possibilities for feasible upgrades of coal power plants: a case of the Electric Power Industry of Serbia
No full textThis paper deals with current status and possibilities for feasible improvement of the flexibility of power generation fleet consisting of aged coal-fired power plants and hydro power plants. The analyses are done by use of well-established deterministic metrics - the normalized flexibility indicator for each power unit is evaluated accounting for ramp up and ramp down power rates as well as the unit operating range. The method is applied to the case of the Electric Power Industry of Serbia (EPS). As expected, hydro power units are highly flexible with normalized flexibility indicator reaching the values as high as 0.78 (on the scale from 0 to 1). The units in power plants fired with lignite are of low flexibility - especially the units with the greatest power where the flexibility indicator is well below 0.2. This issue can represent a serious constraint for operation of these units in conditions of variable demand and future implementation of renewable energy sources with intermittent power generation.
In units of lignite fired power plants the operating range (formulated as difference between maximal and minimal net electric power) is a stronger limitation than the value of ramp up / down rate. Therefore, the efforts for flexibility enhancement focus on lowering of minimal or increase of unit maximal power. In literature various technical measures are considered for this purpose. Despite their undoubtably positive impact, some of these measures (for example, implementation of additional boiler or replacement of thick-wall by thin-wall parts) would represent such a drastic surgery for the aged lignite fired power fleet that they cannot be considered as feasible. For that reason, we analyse sophisticated technical measures which contribute to flexibility increase, but do not require too high retrofitting costs. The solutions are based on (i) advanced operational procedures for feedwater redistribution (ii) installation of additional economizers for recovery of flue gas heat and (iii) implementation of steam accumulators
Application of open source solutions in the realization of low cost teaching laboratories
No full textTeaching in engineering study programs includes practice that often takes place in laboratories. The implementation of
these laboratories is often accompanied by certain limitations and complexities. This paper will show how some of
these problems can be overcome by using open source solutions on the example of one such laboratory for basic and
master academic studies in the mining engineering program, where students are given practical skills in of working
with sensors, process monitoring, and similar activities
Energy efficiency in electric vehicles
Get PDFThis paper deals with research and analysis of energy efficiency in electric vehicles. In the
context of the increasing popularity of electric vehicles as a viable alternative to traditional internal
combustion vehicles, it becomes crucial to understand and improve their efficiency Factors affecting efficiency are considered, including aerodynamics, vehicle mass, electric drive and battery efficiency, as well as the influence of external factors such as route driving and speed. The research
results were then analyzed in order to determine the key factors that can increase the efficiency of
electric vehicles, such as optimizing aerodynamics, reducing vehicle mass and recovering braking
energy, which can significantly improve energy efficiency. Different ways of optimizing the electric
drive and batteries were also investigated in order to reduce energy loss during driving.Ovaj rad se bavi istraživanjem i analizom energetske efikasnosti kod električnih vozila. U
kontekstu sve veće popularnosti električnih vozila kao održive alternative tradicionalnim vozilima
sa unutrašnjim sagorevanjem, postaje ključno razumeti i unaprediti njihovu efikasnost. Razmotreni
su faktori koji utiču na efikasnost, uključujući aerodinamičnost, masu vozila, efikasnost električnog
pogona i baterije, kao i uticaj eksternih faktora poput rute vožnje i brzine. Zatim su analizirani rezultati istraživanja kako bi se utvrdili ključni faktori koji mogu povećati efikasnost električnih
vozila, kao što su optimizacija aerodinamike, smanjenje mase vozila i vraćanje energije kočenja,
koji mogu značajno poboljšati energetsku efikasnost. Takođe su istraženi i različiti načini optimizacije električnog pogona i baterija kako bi se smanjio gubitak energije tokom vožnje
Biomedical Engineering and Additive Manufacturing
Get PDFAdditive manufacturing (AM) technologies have evolved significantly in recent decades, bringing new trends to production processes. The advantages compared to conventional technologies are numerous: production is simpler and faster, geometry can be adjusted more easily, the quality of finished parts is better, less material is wasted, and costs are lower. Because of the wide range of
possibilities, the different AM processes and the materials that can be used, these technologies have found their place in many industries, with significant application in biomedical field. Flexibility in geometric freedom, in particular, is important for the fabrication of biomedical devices. AM technologies proved that diagnostics is facilitated and improved through the fabrication of customized and in-demand parts, consultation between physicians and patients are supported, and thus the opportunity to develop individualized, patient-specific medicine is provided. This review briefly outlines current applications and AM processes in the biomedical field
Testing Surface Properties of 3D Printed Metals
Get PDFThe rapid development of additive manufacturing technologies has opened novel opportunities for producing metal components with a variety of uses. 3D printing of metals provides the capability to produce parts with complex geometry and offers design freedom that cannot be achieved through conventional methods. That is the reason why 3D printed metal parts are increasingly finding applications in areas such as automotive, aerospace, and tool manufacturing. Surface properties of 3D printed metal components are of great importance for the functionality of machine systems, because they often operate under conditions where contact stresses occur. There is just one standard that deals with the measurement and characterization of the surface texture of 3D printed metals – ASTM F3624-23 [1]. Generally, methods for testing surface properties are divided into two groups: non-destructive and destructive methods. The most commonly nondestructive methods for the determination of surface roughness are SEM, EDS, and XRD analysis. Also, all other ultrasonic thermographic, laser, atomic force microscopy (AFM), X-ray, magnetic, and eddy current methods (ETC) can be applied, but their limitations must be taken into account. Usually, post-processing methods are used to reduce the roughness of parts. It has been shown for stainless steel 316L that shot peening can reduce up to 50% of the average surface roughness [2]. Tribological properties are very important in cases where contacting parts is in the relative motion.For determining tribological properties well-known testing methods are adapted for 3D printed metals. The most commonly used are dry erosion, slurry erosion and high-stress abrasion tests on stainless steel 316. Testing procedures of ASTM B611 and ASTM G65 standards are used for determining wear properties of 3D printed cemented carbide, which is not metal, but that procedures can be applied on 3D printed metals [3]. For measuring the hardness of 3D printed metals the Vickers method is most frequently used. A large number of parameters such as AM technology, printing direction, postprocessing, and layer thickness influence surface properties. In general, surface characteristics of 3D printed metals are not extensively researched and can represent a significant area for investigation, especially when considering all influencing parameters
The Sustainability Analysis of Women-owned Businesses Examined Through the Impact of Selected Variables on Dimensions of Innovation Capacity
No full textInnovation is often described as the main driving force of business, which can lead to the company's sustainable growth. Not all innovation dimensions are equally responsible for the sustainability of businesses. Therefore, this study examines the sustainability of women-owned businesses by exploring the influence of selected variables on specific dimensions of companies' innovation capacities. Based on the commonly applied methodologies for assessing the innovation capacity of companies such as IMP³rove and Innovate, the following variables were chosen for the analysis of the impact on innovation in the context of the sustainability of SMEs: 1) annual income and its impact on the decision to invest in innovation 2) the sector of operation and its influence on expectations regarding growth 3) the expectations regarding growth and its impact to a range of innovation dimensions. Different techniques were used, starting with descriptive statistics, then Cross-tabulation, Pearson's chi-square test and ANOVA as the most appropriate techniques to conduct statistical analysis. The research has indicated that annual income does not have a decisive influence on the decision to invest in innovation, as does the sector. However, the sector of operations has a significant influence on expectations regarding growth. Also, there is a statistically significant difference between growth expectations and dimensions such as client base and product development plan, market awareness and perception, innovation strategy, decision-making process, employee training, business networking, and external advice. While exploring the innovation activity of launching new products/services, we came to a finding that is potentially risky for the sustainability of women’s businesses, namely that 50% of the companies in the sample offer only one product to one customer. That is why it is important that companies that have a high awareness of the need to innovate diversify their product and client portfolio and thus ensure greater independence on the market and, therefore, sustainability
Methodology of experimental optimization of atmospheric burners for household appliances
No full textThe aim of this experimental research is to confirm the correctness of the proposed methodology for optimizing atmospheric gas burners. Also, the burner was tested in actual conditions. The object of this experimental optimization is a typical modern atmospheric gas burner for households (required heat output for average households ranges from 8 to 12 kW) to which the proposed methodology will be applied in order to optimize its design characteristics and performance to obtain energy efficient and an environmentally friendly device
Analysis of remediation of horizontal cylindrical tank for oil storage
No full textThe paper deals with the problems related to the horizontal cylindrical tank with capacity 52m3 for oil storage, which is in long time continual service. Before planned change of location necessary planned cleaning and inspection activities were performed. During inspection process cracks were observed in base metal and on internal side at reinforcement plates. Cracks were analysed and confirmed by detail visual and dye penetrant tests. Appropriate remediation documentation was prepared before starting of cracks excavation process. All cracks were fully removed which was confirmed by relevant NDT-tests. Repairing welding activities and appropriate NDE-examination tests after repairing welding process were performed. After successfully leak test, tank was transferred on the new location and put in service
