EUREKA: Physics and Engineering
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Potential valorization of demolition concrete waste in the design of low and medium traffic roads
Full text linkThe construction and the maintenance of road infrastructure consume every year and all over the world a huge amount of natural aggregate, such as crushed stone, gravel, and sand. This dependence on natural aggregates has not only placed tremendous pressure on our environment but has also resulted in severe consequences such as loss of biodiversity, and long-term environmental degradation. As road infrastructure projects expand to accommodate growing populations and urbanization, the extraction and consumption of these natural materials increase exponentially. This creates an urgent need to explore more sustainable and eco-friendly alternatives in order to reduce the environmental footprint of road construction projects. A sustainable solution to reduce the use of naturel aggregate in road pavement is incorporating recycled materials – specifically, recycled construction and demolition waste (RCDW) aggregates – in their construction. These aggregates are derived from dismantled structures and other construction waste. This study aims to evaluate the viability of employing RCDW aggregates in the design of unbound pavement layers. A comprehensive laboratory program was implemented to assess the geometrical, physical, and mechanical properties as well as the bearing capacity of these recycled aggregates. The results indicate that RCDW aggregates exhibit suitable performance characteristics in term of hardness (LA <30 % and MDE <30) and bearing capacity (immediate CBR index >80 %), making them a viable option for use as coarse base and sub-base layers in roads subjected to low to medium traffic volumes. Consequently, these recycled aggregates meet the majority of the specifications required for untreated grave
Scientific analysis of the development of new types of flotation reagents used in coal enrichment
Full text linkIn this study, new flotation reagents were developed for the coal beneficiation process, and their effectiveness was evaluated using experimental methods. The main objective of the research is to improve the efficiency of the beneficiation process by enhancing the physical and chemical properties of coal. For this purpose, various spectroscopic and chemical analysis methods, including X-ray fluorescence (XRF), X-ray diffraction (XRD), and infrared (IR) spectral analysis techniques, were employed.
The results demonstrated that the use of the newly developed SFKM-2 composite flotation reagent increases the calorific value of coal while also reducing the environmental impact of coal residues. The study's findings propose new approaches to enhancing the efficiency of flotation reagents and open up possibilities for industrial-scale applications.
The technological scheme of coal enrichment by flotation method is described. In order to develop a waste-free technology, a chemical analysis of the waste produced as a result of the enrichment was carried out. Acidic oxides are formed as a result of combustion of sulfur in coal. The use of silicon compounds with a crystalline structure is one of the requirements for silicon compounds used in the glass industry. Coals passed through the drum are processed in a flotation reactor and sent to a coal dryer. Enriched and dried coals are sent to a briquetting machine and a finished product in the form of briquettes is obtained. In addition, the developed SFKM-2 composite material IK -spectrum image and image data are presented. The ash content was analyzed by the X-ray fluorescence method and the results were presented and scientifically analyzed. Additives were added to the flotation device, new flotation reagents and collectors were use
Combustion characteristics of Biosolar B20 fuel enhanced with clove oil (syzygium aromaticum) bioadditives
Full text linkThis study focuses on improving the combustion characteristics of Biodiesel B20 fuel by adding clove oil (Syzygium aromaticum) as a bioadditive. The main issues addressed are improving combustion efficiency and reducing emissions, which are crucial for advancing sustainable biodiesel solutions. This study investigated the effects of varying concentrations of clove oil (1–5 ml) on key combustion parameters such as ignition delay, combustion duration, peak temperature, and emissions.
The experimental results showed that adding clove oil to Biodiesel B20 significantly reduced the ignition delay and combustion duration, indicating improved combustion efficiency. In addition, the peak temperature was higher for the fuel blend with clove oil, indicating improved thermal performance. Emission analysis revealed a decrease in harmful emissions, supporting the environmental benefits of clove oil bioadditive.
These findings are explained by the high eugenol content in clove oil, which facilitates better combustion due to its oxygenated compounds. The reduction in ignition delay and combustion duration, along with the increase in peak temperature, indicates more efficient and complete combustion.
The results showed that clove oil bioadditive can improve the performance of Biodiesel B20 by increasing combustion efficiency and reducing emissions. These features make clove oil a viable bioadditive for developing more efficient and environmentally friendly biodiesel blends. The practical use of these findings is relevant for biodiesel producers and environmental policy makers aiming to promote sustainable energy solutions. The results contribute to the optimization of biodiesel formulations, supporting the global transition to renewable energy source
Multi-objective decision making in EDM using AlCrNi coated aluminum electrode: topsis approach
Full text linkIt is very important to find the optimal set of technological parameters in traditional or non-traditional machining technology. It has special practical significance for multiobjective problems. In micro-EDM, the complexity of the number and range of changes of the technological parameters, and the mechanism of spark formation are precisely controlled. The influence of interference factors includes the uniformity of the dielectric solution, the chip particles existing in the discharge gap, the conductivity of the electrode, etc. This has led to the need of optimizing the technological parameters in micro-EDM. The method of determining the optimal set of parameters was different, and the optimal results of each different method were also different. This has led to a decrease in the reliability of the optimal results. Therefore, it is necessary to study and evaluate the suitability of each method in each specific technical problem. Electrical discharge machining (EDM) using coated electrodes has piqued the interest of many technical specialists owing to its efficacy in enhancing the machining process. However, there have been relatively few studies on improving technical parameters in EDM with coated electrodes, resulting in a major drop in productivity and quality in reality. In this research, the adjustment technology parameters are improved in the multi-objective choice problem in EDM technology utilizing AlCrNi (Aluminum-Chromium-Nickel) coated electrodes. The AlCrNi alloy layer was coated with an aluminum (Al) base electrode, whereas the workpiece was made of titanium alloy (Ti-6Al-4V). The voltage (U), current (I) and pulse on time (Ton) were considered the technological parameters. The material removal rate (MRR) and surface roughness (SR) are employed in this investigation. The Taguchi-Topsis approach is used to address the multi-objective decision issue. The ideal process parameters are U=50 V, I=20 A, Ton=1000 µs, MRR=0.0151 mg/min, and SR=7.215 µm. Combining Taguchi and Topsis is a multi-objective decision-making approach that improves economic and technological efficienc
The effect of mass fraction of fly ash and gravel on mechanical properties of mineral cast
Full text linkThe effect of the mass fraction of coal fly ash and gravel on the mechanical properties of mineral cast has been investigated. The percentage mass fraction variations of fly ash/gravel were 100/0, 75/25, 50/50, 25/75, and 0/100. This study used epoxy resin as the matrix; the mass fraction of epoxy resin in composite is about 15–25 %. The components of the mineral cast were mixed using conventional concrete mixers and then poured into cast steel molds. The specimens for tensile, bending, impact, and damping ratio tests were made from 160×40×10 mm mineral cast blocks and cut by water jet cutting. The tensile, three-point bending and impact tests were carried out according to ASTM D638, ASTM D790, and ASTM E23, respectively. The compression test specimen o was produced by pouring the compound of mineral cast in the cylinder steel molds with 75 mm diameter and 150 mm height, according to the ASTM C39 standard. The density of mineral cast composites was measured based on Archimedes' law. The results show that the density of the mineral cast composites decreases as the percentage of epoxy resin increases. The lowest density is 1.80 g/cm3 on mineral cast with 100 % gravel and 25 % wt. epoxy resin. The higher percent mass of epoxy resin increases compressive, tensile, and flexural strength. The mineral cast composite with 100 % gravel and 25 % wt. epoxy resin results in the highest compressive strength. The trend indicates that the rise of fly ash composition decreases the compressive strength value of the mineral cast. Increasing % wt. fly ash insignificantly increases the tensile and flexural strength. The minerals cast have a damping ratio of about 0.0241–0.044, which is higher than the damping ratio of cast iron. The research shows that mineral cast composite made from fly ash and gravel reinforced with epoxy resin can be applied as a material for the machine tool be
Study on the terrain response of armored rescue vehicle
Full text linkMany countries with underdeveloped economies tend to improve military vehicles to enhance their effectiveness by integrating additional equipment into existing vehicles. Armored personnel carriers can be integrated with crane systems and cables to function as cranes for rescue and recovery operations on the battlefield. This paper proposes a dynamic model for a military armored recovery vehicle moving on randomly rough roads in a suspended payload state. The randomly rough roads of classes D, E, and F, as described in the ISO 8068 standard, are considered as factors influencing the vibration of the vehicle during movement. The research model is a 2D multi-body system, considering the elasticity of the tires, suspension system, and cables, while neglecting the elastic slope of the ground. The system's motion differential equations are solved through simulations using Matlab/Simulink software. The results indicate the displacement of the vehicle chassis and the oscillation of the payload corresponding to speeds of 1 m/s, 1.5 m/s, and 2 m/s. The payload's tilt angle can reach nearly 40° when the vehicle moves at a speed of 2 m/s on a type F road, corresponding to a travel distance of about 30 meters. Meanwhile, the maximum tilt angle is about 19° when the vehicle moves at the same speed on a type D road. The chassis, boom, and payload experience stronger oscillations when the vehicle moves faster and on rougher terrain. The paper recommends practical engineering solutions to minimize load oscillations during vehicle movement. The findings of this paper provide a basis for evaluating the operational capability of an armored personnel carrier integrated with a crane, contributing additional theoretical insights into machine dynamics and holding significant importance in the military fiel
Improvement of peat soil using microorganisms for subgrade reviewed from CBR value
Full text linkPeat soil is well known as problematic soil because of its poor geotechnical properties such as high-water content, low shear strength, high organic matter, low bearing capacity and high compressibility. Due to these geotechnical issues of peat soil, improvement of the soil is essential in order to enhance its engineering properties. Peat soils are formed from a mixture of fragments of organic material originating from decaying plants, whether weathered or not. The physical and mechanical characteristics of peat soil are strongly influenced by the degree of decomposition. To accelerate the decomposition of peat soil is to add microorganisms. The microorganisms are used as the soil stabilizer in order to investigate the optimum percentage of microorganism as the stabilizing agent on peat soil. The purpose of this research is to investigate the physical and mechanical changes in fibrous peat soil of laboratory test after adding microorganisms. The volume of Microorganisms added and mixed with peat soils varied with 5 %, 10 %, 15 %, and 20 %. There are 4 variation percentage of microorganisms to dry soil such as laboratory test are fiber content, ash content, organic content, acidity level (pH), compaction (standard proctor test), California bearing ratio. The variation of the highest CBR were treatment in 7, 14, 28 days. The results show that microorganisms improve the physical and mechanical properties of peat soil. The most significant result on the physical and mechanical properties of peat soil was 20 % microorganisms. The increase value of unsoaked CBR from 2.86 % to 10.47 % and in soaked condition from 2.51 % to 9.24 %
Verification of artillery systems' shots: selection of the most appropriate sensors based on the fuzzy evaluation model
Full text linkLong-range artillery remains vital in modern warfare, where precision and innovative methods are key to completing fire missions with fewer rounds. Developing advanced techniques of artillery shots verification based on sensor systems that maximize target destruction with minimal ammunition and exposure time is essential for maintaining the combat effectiveness of artillery units. Moreover, one of the complex and important tasks that must be solved in the verification process before each shot is to determine the optimal combination of three sensors from the entire available set included in the sensor system in the firing zone.
To solve this problem the paper introduces an approach for selecting the three most appropriate acoustic sensors for artillery shot verification using a fuzzy evaluation model. The approach considers location, measurement error, and probability of failure-free operation at selecting sensors to effectively register ballistic and muzzle waves, with further assessment of the suitability of each sensor. For adequate assessment of acoustic sensors, the presented approach uses a developed fuzzy logic model that allows calculating the value of the sensor suitability criterion for the verification of the current artillery shot. A computational experiment with fixed artillery shot parameters was conducted to evaluate the proposed approach and fuzzy model, successfully identifying three optimal acoustic sensors for precise recording of ballistic and muzzle waves. The obtained results confirm the effectiveness and feasibility of the proposed approach and fuzzy model for selecting the best sensors for artillery shot verification and determining projectile impact coordinates under random disturbances
Technologies for efficient grinding of plant and animal waste: a review
Full text linkThe article considers the issue of technologies for grinding waste of plant and animal origin. A review of modern research works for the period 2020–2024 is conducted. The analysis of scientific works has revealed 10 most promising technologies that can grind waste of plant and animal origin. A comparative analysis of the research results and available information on each of the technologies for grinding waste of plant and animal origin is carried out, establishing the methods of destruction, the name of the crushing and grinding equipment and working bodies, advantages and disadvantages. It was revealed that water-jet technology has great potential, in which the cutting speed reaches 1000 m/s due to the high-energy water flow, capable of providing preliminary destruction of wood and meat and bone waste of various thicknesses. Many scientific articles focus on the issue of grinding secondary raw materials for the purpose of preparing feed, since waste of plant and animal origin has biologically valuable properties for the production of high-quality feed. Separately, it should be noted that all waste grinding technologies are based on the use of technical devices. In this case, such working bodies as hammers are significantly used in crushing. The review indicates 11 hammer designs with 2 to 8 working surfaces on one hammer, 2 to 6 hinge holes on one hammer, and 18 to 240 sharp ends on one hammer. It has been established that the trend in improving hammers is to eliminate passive zones on working surfaces, ensure a longer service life of hammers and hammer hinge holes by using new hammer surfaces, and provide the working surfaces of hammers with sharp ends to combine impact-cutting effects for the purpose of intensive crack formation in the crushed particle
Prospects for the creation of small-sized high-speed unmanned aerial vehicles based on WIG-craft
Full text linkWIG-craft are high-speed vehicles that use the dynamic principle of support above the ground. Today, the current examples and projects of such vessels concern, mainly, only large-sized or medium-sized manned vehicles, for which it is possible to ensure stable aerodynamic characteristics during flight. At the same time, modern trends in the development of vehicles indicate a growing interest in small unmanned vehicles. Currently, the issue of creating small manned and unmanned WIG-crafts has become relevant. In the presented work, based on the von Karman–Gabrielli methodology, the efficiency of transport WIG-craft among other types of vehicles was evaluated. The possibility of using such small-sized devices as unmanned devices is considered. The productivity of a WIG-craft is depends on its aerodynamic characteristics. Scale factor is very important for WIG-craft, because the aerodynamics is depended on wings size. The design of a small-sized WIG-craft based on the aerodynamic scheme of an airplane is proposed. The aerodynamic characteristics of the proposed device were evaluated using CFD modeling. Outcomes indicates that the aerodynamic properties of a ship are greatly affected by clearance and velocity. Ground effect is allowed to increase the aerodynamic quality up to 1.5 times, provide the transport of payloads at velocities as high as 250 km/h with a take-off weight of 2.7 tons. The analysis of computation results shows that the proposed project of an unmanned WIG-craft is fully operational and promising for solving the problems of high-speed delivery of small payloads. According to the computation results of the aerodynamic characteristics, the specific power of the device was determined, which indicates the high theoretical efficiency of the proposed means