2020, Vol. 18, Special Issue 1

Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/6026

Sirvi

Nüüd näidatakse 1 - 20 39

Utilization of fused deposition method 3D printing for evaluation of discrete element method simulations
(2020) Hnízdil, P.; Chotěborský, R.; Kuře, J.
FDM 3D printing is used for designing prototype assessment in engineering production. It is usually used to verify the functionality of kinematics mechanisms. It can also be used for innovation in agricultural production, eg. the development of new mechanisms for agriculture tools. Such a mechanism as well as the entire components is printed using FDM and they are made of plastics. This whole can be experimentally verified in a laboratory trough. The article deals with the verification of the possibilities of using FDM technology for the design of agricultural tools. The material properties, namely stress-strain, of the plastics after printing are entered into the Ansys mechanical library, and the DEM results are also imported into Ansys mechanical. Material properties of plastics for FDM technology such as PLA, PETG show that its mechanical properties limited their using for validation.
Characterization of materials used in the manufacture of ceramic tile with incorporation of ornamental rock waste
(2020) Luiz, N.F.; Cecchin, D.; Azevedo, A.R.G.; Alexandre, J.; Marvila, M.T.; Silva, F.C.; Paes, A.L.C.; Pinheiro, V.D.; Carmo, D.F.; Ferraz, P.F.P.; Hüther, C.M.; Cruz, V.M.F.; Barbari, M.
The production of ceramic tiles, such as tiles, has a great environmental impact, either in the extraction of natural raw materials or gas emissions in the burning stages. The use of industrial solid waste in ceramic materials can contribute to the reduction of these impacts, according to the characteristics of solid waste and its interaction with ceramic materials in the processing steps. Thus, this study aimed to characterize the materials needed to make a ceramic tile with incorporation of ornamental rock waste (ORW), thus evaluating its main characteristics regarding the feasibility of this incorporation. The physical characterization of the clays used in the production of ceramic artifacts was performed, and for the waste the mineralogical analyzes were performed, through x-ray diffraction (XRD), microstructure analysis from confocal optical microscopy, after sintering the prototypes and chemical analysis by X-ray spectroscopy (EDX). Soon after the raw materials went through the step of conformation and preparation of the prismatic specimens by the process of extrusion of the ceramic mass, with an incorporation of the ORW in 0% and 15% of the ceramic mass, for its subsequent The prototypes were sintered at three different temperatures (850 °C, 950 °C and 1,050 °C). The specimens were submitted to technological tests of mechanical resistance, water absorption, firing shrinkage and porosity to evaluate the incorporation viability. The results indicated the presence of quartz particles in all raw materials, and also that the clays of the study region are predominantly kaolinitic. The presence of these materials in the ceramic masses directly influences the micrographs, because they result in the formation of liquid phase, inert particles that can turn the site into a stress concentration point and when incorporated in the ORW the specimens met the technical specifications of the Brazilian standard for application on ceramic tiles. The results found in the technological tests carried out, that the incorporation of 15% of ornamental rock waste in both clays did not affect the tile properties, indicating the feasibility of incorporating this waste in civil construction, minimizing the impacts generated.
Comparison between the thermal properties of cement composites using infrared thermal images
(2020) Ferraz, P.F.P.; Mendes, R.F.; Ferraz, G.A.S.; Damasceno, F.A.; Silva, I.M.A.; Vaz, L.E.V.S.B.; Mendes, L.M.; Cecchin, D.; Castro, J.O.
The use of agribusiness residual lignocellulosic fibres can be a good alternative in the development of lignocellulosic composites. The current work aimed to investigate the thermal performance of cement-based composites with lignocellulosic materials: Eucalyptus, sugarcane bagasse, coconut fibre in comparison with commercial gypsum board to be used as internal partitions of the building using infrared thermal images. Three repetitions for each kind of lignocellulosic material were made, and three commercial gypsum boards were used. In the production of the panels, the following parameters were applied: material and cement ratio, 1:2.75; water and cement ratio, 1:2.5; hydration water rate of 0.25; additive, 4% (based on cement mass). The calculations were performed for a nominal panel density of 1,200 kg m- ³. The thermal analysis was performed in a chamber composed of MDP (Medium-Density Particleboard) and with an internal layer of rock wool and the heat source (thermal resistance). For the superficial temperature measurement, a FLIR E75 camera was used to capture the infrared images. When the internal temperature of the chamber stabilized at 50 °C, an infrared thermal image was collected from each side of the composite. Thermal properties were analysed: thermal conductivity, resistivity, resistance, and transmittance. Based on the results, sugar cane cement composites were characterized by higher values of thermal conductivity. Related to thermal resistivity, thermal resistance, and thermal transmittance, only the coconut panel presented similar behaviour to the commercial gypsum board. Thus, cement composite using coconut can be a potential alternative that might solve energy and environmental concerns simultaneously.
Chemical analyses of lignocellulosic materials residue for cement panels reinforcement
(2020) Ferraz, P.F.P.; Mendes, R.F.; Ferraz, G.A.S.; Rossi, G.; Conti, L.; Barbari, M.
The use of lignocellulosic material residue in cement composites is on the rise as sustainable building materials in most developing countries. Besides, this alternative is seen as a good option for new cement panels formulations for indoor applications. Thus, the current paper aims to evaluate de chemical properties of five potential lignocellulosic materials residues to be used for cement panels reinforcement: Eucalyptus, sugarcane bagasse, coconut fibre, coffee rusk, and banana pseudostem. The following physical properties of the lignocellulosic materials were evaluated: lignin, extractives, ash, and holocellulose. To evaluate the similarity of the chemical composition of the lignocellulosic materials, Hierarchical Cluster Analysis (HCA) was used identified by using Ward’s method of cluster analysis. These compositions were grouped by dendrograms in which the similarity of these data was qualified. It was observed that there were statistical differences among all types of lignocellulosic materials related to the chemical composition. Coconut showed the smallest amount of extractives, and sugar cane the most significant amount. Eucalyptus and coffee husk presented the most similar chemical composition. All of the evaluated materials could be used in fibre cement production for indoor applications.
Comparison of phosphorus removal efficiency of conventional activated sludge system and sequencing batch reactors in a wastewater treatment plant
(2020) Denisova, V.; Tihomirova, K.; Neilands, J.; Gruskevica, K.; Mezule, L.; Juhna, T.
The aim of this study was to evaluate the effectiveness application of sequencing batch reactors (SBRs) for phosphorus removal compared to the conventional activated sludge (CAS) treatment system. The results showed that the removal efficiency of phosphorus reached about 99% at wastewater treatment plant with CAS system. At the same time, the maximum phosphorus removal efficiency can be achieved to 88% if the SBRs system operating parameters are optimized. Finally, this study demonstrated that even if granules are not fully developed, the SBR system is working with a good efficiency.
Recognition of retroreflective traffic signs by a vehicle camera system
(2020) Khrapova, M.; Růžička, M.; Trnka, V.
The systems of traffic sign recognition are based on the evaluation of three components of every sign: shape, colour and pictogram. There are different factors that can have an influence on the efficiency of detection and recognition of these components. One of the most important factors is the quality of the retroreflective sign surface. Retroreflective sheeting improves the readability of colour and pictogram of traffic sign by increasing brightness of its background and/or legend elements. The aim of the paper is to provide a comprehensive survey of the efficiency of sign’s recognition by a modern vehicle camera system. The traffic sign sheeting was measured by the handled retroreflectometer. Then this measurement was repeated by the modern camera system used for recognition of traffic signs in the vehicle. The results of this paper present the analysis of the recognition efficiency of traffic signs and the overview of other factors that can have a significant impact on sign detection and recognition distance. The results can be used for creation a traffic sign database for learning-based recognition techniques to vehicle camera systems.
New approach for recycling spare parts, components and assemblies
(2020) Mitrofanovs, V.; Boiko, I.; Geriņš, Ē.
Recycling and disposal are one of the most complicated topics in the lifecycle of a mechanism, especially in case of previous generations of machines that were designed without taking any care of post exploitation period. In the current work, the ‘feasibility points’ of recycling units, methods of recycling as well as pricing formation for recycling materials, reviewed and proposed by several world universities and scientific bureaus and applied by major world brands have been analysed. The general principles that should be rated as a basis when designing and creating new mechanisms, as well as the actions which we consider as a necessary supplement to the existing rules of the lifecycle of assemblies and which should be applied in practice, were introduced by authors in the ‘Management of parts and components for units and assemblies in mechanical engineering industry and its impact on the environment’. It was discovered that even modern assemblies, not to mention previous generations, are being designed without taking into consideration any possibilities of easy recycling the used materials. The number of components of mechanisms, which are being repaired as assemblies, is continuously increasing, while maintainability and repairability of separate parts is decreasing. Taking into account the state of the art in the field, the new approach for promoting the reusing natural resources and decreasing the harmful effects of obsolete components of mechanisms on the environment is proposed. Thus, using the fast-moving parts that in post operational period can be easily detailed by type of a material will ensure more efficient consumption of natural resources. Our research and developments significantly reduce the costs of recycling and these materials become competitive comparing to the new ones. Taking into account the state of the art in the field, the new approach for promoting the reusing natural resources and decreasing the harmful effects of obsolete components of mechanisms on the environment is proposed.
Thermal decontamination of sewage sludge
(2020) Dubova, L.; Strunnikova, N.; Cielava, N.; Alsina, I.; Kassien, O.; Bekker, A.
Every year a huge amount of sewage sludge is formed at municipal wastewater treatment plants. Sewage sludge contains a sufficient amount of biogenic elements and organic components, which characterizes them as possible raw materials for the production of organic fertilizers. However, direct incorporation of these sediments into the soil is impossible due to the fact that, in addition to useful organic and mineral components, they contain pathogens, viruses and helminth eggs. The aim of the study was to optimise thermal disinfection conditions for preparing of safety sewage sludge fertilizer. Laboratory studies were carried out using sediments from wastewater treatment plants of some cities. During laboratory experiments, the conditions for thermal disinfection of sediments – the thickness of the sediment layer, the air temperature in the disinfection furnace, and the treatment time of the sediment – were determined. When conducting industrial tests of a conveyor-type sediment decontamination furnace, the operating conditions of the furnace were determined, i.e., the temperature regimes of the sludge heating zone, the decontamination zone and the cooling zone, and the optimum parameters of the sludge layer thickness on the conveyor and the conveyor speed were determined.
Non-Invasive measurer for methane and carbone dioxide emissions in bovine cattle through TRIZ
(2020) Silva-Martínez, K.L.; Cruz-Rivero, L.; Arrieta-González, A.; Purroy-Vasquez, R.
Greenhouse gases (GHG), mainly methane (CH4) and carbon dioxide (CO2), can be generated in agricultural activities, not only in waste but also in the process of breathing of livestock. The Theory of Inventive Problem Solving (TRIZ) is an innovative Russian methodology that allows finding the solution to a problem raised. This paper presents the use of two TRIZ tools to design a non-invasive prototype that detects CH4 and CO2 emitted by cattle in real time. The tools were the matrix of technical contradictions and the nine-screen analysis with which the parameter to be improved (A) was found and the best possible solution to design a prototype that allows quantifying gases for animal welfare, Final Ideal Result (IFR) a wireless module with a sensor system for each of the gases placed on the bovine head, which convert the detected gas into an electrical signal to be sent wirelessly to a range of 1.5 km in free space at a receiver for its visualization representing the parts per million (ppm) of CH4 and CO2 that the bovine is generating during the measurement.
Thermal analysis of cement panels with lignocellulosic materials for building
(2020) Ferraz, P.F.P.; Mendes, R.F.; Ferraz, G.A.S.; Carvalho, V.R.; Avelino, M.R.C.; Narciso, C.R.P.; Eugênio, T.M.C.; Cadavid, V.G.; Bambi, G.
The use of lignocellulosic material residue in cement composites can be considered as a good option because they allow good thermal behaviour. This paper aimed to compare three kinds of cement panels reinforced with different lignocellulosic materials (Coffee husk, Coconut shell, and Banana pseudostem) based on their thermal properties. To produce each panel, the methodology suggested by Souza (1994) was used. Six replicates of each lignocellulosic panel with dimensions of 7.0×7.5 were evaluated. The thermal analysis was performed in a chamber composed of MDP (medium density particleboard). The chamber contained the heat source (incandescent lamp) connected to a thermostat that maintained the temperature at 48.0 °C. The porosity and thickness of the panels and the thermal behaviour of each sample panel (thermal conductivity, resistivity, resistance, and transmittance) and the difference in temperature of both sides of the panel were evaluated. The temperature difference to stabilization was obtained after a sampling time of 200 minutes, with 1,000 readings of 12 s each. Although all the panels were submitted under the same temperature, the inner and external superficial temperatures of the coffee husk panels reached smaller values. Besides, coconut and banana pseudostem panels presented the best results of thermal transmittance and thermal resistance. Thus, coconut shell panels present the best thermal performance, which means that this panel might be an attractive alternative building material, in terms of heat insulation for indoor applications.
Psychosocial risks analysis for employees in public administration
(2020) Pastare, D.; Roja, Z.; Kalkis, H.; Roja, I.
Nowadays psychosocial risks at work have a serious impact not only on the health of employees, but also on the economic performance of organisations, and this is the biggest challenge in working environment. In Latvia, employees in public administration comprise 11% of the total population. Hence the aim of this study was to analyse the causes of psychosocial risks and the differences in their prevalence among inspectorate officials employed in the State Administration compared to office staff employed by the State Administration. A modified Copenhagen Psychosocial Questionnaire from the Danish National Research Centre for the Working Environment was used to assess psychosocial risks at work. One public administration organisation was selected for the study, which involved 111 staff (60 inspecting officers and 51 office staff). The analysis of the results of the psychosocial risk assessment shows that there are statistically significant differences in the assessment of four out of 11 psychosocial risks to the working environment. The most common psychosocial work environment risk factor among inspectors is the inadequate attitude of management, but the most common risk factor among office employees is the lack of impact on work. To reduce the spread of psychosocial risks more effectively, an individual approach is required for each worker.
Tensile properties of wood plastic composites based on plant-filled polyvinyl chloride/poly(3-hydroxybutyrate-co-3- hydroxyhexanoate) matrices
(2020) Samuilova, E.O.; Podshivalov, A.V.; Fokina, M.I.; Chursina, V.S.; Strelnikova, I.E.; Uspenskaya, M.V.
The article considers the obtaining and studying of microcomposites based on polyvinyl chloride (PVC)/poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) polymer matrix, filled with a various faction of different natural plant fillers. In work, such plant fillers as wood flour without lignin, spruce flour and rice husk were used. Microcomposites were obtained by melt rolling processing method with subsequent analysis of their morphology and mechanical tensile properties. It is shown that the filler particles were strongly oriented in the direction of the melt rolling process and have a different aspect ratio depending on the filler type. The tensile strength of materials strongly depends on the particle’s aspect ratio. When the aspect ratio of the particles is 4.25, the material has a strength value comparable to a pure PVC/PHBHHx matrix.
The experimental investigation of the mechanical properties of steel fibre-reinforced concrete according to different testing standards
(2020) Ryabchikov, Alexander; Kiviste, Mihkel; Udras, Sten-Maikel; Lindpere, Mart; Vassiljev, Anatoli; Korb, Nikolai; Estonian University of Life Sciences. Institute of Forestry and Rural Engineering. Chair of Rural Building and Water Management
Steel fibre-reinforced concrete (SFRC) is widely applied in the construction of civil infrastructure projects, including the following: industrial floors, slabs, walls, and foundations. The application of steel fibres in the reinforcement of concrete remarkably improves the postcracking behaviour of such concrete. In order to estimate this property, the energy involved in absorption is measured by using several valid testing standards: EVS-EN 14651:2005, EVS-EN 14488-5:2006, and ASTM C1550-12a. The objective of this study was to carry out a comparable analysis of the results that have been obtained using previously-mentioned standards and to be able to find a more reliable method for the determination of the fracture toughness of SFRC specimens. Experiments were carried out in accordance with the chosen standards. It was concluded that procedure involved in the ASTM standard provides a smaller variability of results with better levels of repeatability, therefore a smaller volume of specimens can be tested in one series in order to achieve reliable results.
Airflow profile study of a compost dairy barn using a low-cost 3D-printed anemometer network
(2020) Vega, F.A.O.; Rios, A.P.M.; Damasceno, F.A.; Saraz, J.A.O.; Nascimento, J.A.C.
Mechanical ventilation is commonly used for environmental thermal regulation inside closed-field agricultural production systems. Analyzing the air distribution inside these facilities and the correct operation of the fans can be a challenging. This could be determined using cost prohibitive techniques as particle image velocimetry or deploying large wind sensors networks on-site. To avoid this limitation without a lack of measurement accuracy, this research was focused on developing and test a low-cost anemometer network based in low cost propeller’s anemometers, built using fused 3D-printed and open-hardware platforms. Four propeller anemometers with three to six blades were simulated using the 6-DOF method of ANSYS computer fluid dynamics software. Similar results were obtained for all the simulated models with minor differences. Anemometers were tested in an open circuit wind tunnel before to be evaluated in two open compost dairy barn building using high-volume low-speed and low-volume high-speed fans. Data were analyzed by employing contour maps, descriptive statistics and correlation. The results show that the anemometer network determines the fan’s wind profile for wind speeds over 0.7 m s-1 and it was possible to determine the facilities spots with ventilation problems. The proposed anemometer network and methodology are a good alternative to analyze the operating conditions of the tested agricultural facilities and optimize its performance.
Investigation of dual varying area flapping actuator of a robotic fish with energy recovery
(2020) Tipans, I.; Viba, J.; Irbe, M.; Vutukuru, S.K.
Autonomous under-water vehicles (AUV) performing a commanded task require to utilize on-board energy sources. At the time when on-board power source runs low during operation, the vehicle (AUV) is forced to abort the mission and to return to a charging station. The present work proposes the technique of an energy recovery from surrounding medium. This effect is studied for dual action actuator movement that obtains energy from fluid. It is realized that a flapping or vibrating actuator can be used for energy extraction phenomenon apart from the non-traditional propulsive technique. In the present work a simple dual flapping actuator that can switch between simple flat plate and perforated plate at extreme end positions (angles) by using an efficient mechatronic mechanism that would help in overcoming viscous forces of the operating medium is extensively studied. The main objective of the present article is to develop a new approach for energy gain and recharge power pack of on-board sources from the surrounding medium and to create a robotic fish that would work autonomously by using unconventional drive along with the possibility of energy restoration by using dual varying area type vibrating actuator. At the time of recharge, the robotic fish would project its tail (actuator) out of water and use surrounding medium (air) to scavenge the energy. All the equations describing the process are formed according to classical laws of mechanics. The mechatronic system is explained and the results obtained are discussed in detail for air as the operating fluid to scavenge energy.
Morpho-physiological effects of Stymjod foliar application on Dactylis glomerata L.
(2020) Sosnowski, J.; Jankowski, K.; Truba, M.; Novák, J.; Zdun, E.; Skrzyczyńska, J.
The aim of the experiment was to study the effects of foliar application of a growth regulator containing iodine nanoparticles, with the trade name of Stymjod, on morphometrics, photosynthetic activity and chlorophyll content of Dactylis glomerate L. The following parameters were determined: the weight of fresh and dry matter of plants, leaves and roots, the number of shoots and leaves, potential (FV/Fm) and effective (F/Fm’) quantum efficiency of photosystem, photochemical (qP) and non-photochemical (qN) quenching, as well as chlorophyll a and chlorophyll b content in leaf blades. The pot experiment was carried out in a breeding room. Stymjod was applied at 1.5%, 3% and 4.5% concentrations in the spray solution. It is a nanotechnology-based growth regulator, with easily assimilable forms of mineral and organic ingredients, favorably affecting plant ontogenesis. Plants were treated twice with a single dose of 50 mL of spray per pot. They were sprayed till they were completely covered with the liquid. Distilled water was used to spray control plants. The results were statistically processed using analysis of variance, while the significance of the differences between means was determined with Tukey's test with P = 0.05. In the experiment it was found that different concentrations of Stymjod in the spray resulted in different response of plants. The best morphological effects were obtained using the concentration of the product exceeding 3%. In the test conditions Stymjod applied to D. glomerata increased the efficiency of the photosynthetic apparatus and the content of chlorophyll pigments.
Qualimetry as productivity criteria in metal-cutting operations
(2020) Maksimov, D.; Kalkis, H.; Perevoschikov, Y.; Roja, Z.
The qualimetry method will allow an objective assessment of the performance of metal-cutting machines and the production capacity of machinery, as well as an objective assessment of their use in multi-product manufacturing, applying the qualimetry approach and qualimetry indicators, which are based on the concept of qualification of metal removing during machine operations. The aim of the study is to develop methods for measuring the performance of metal-cutting machines and open the way to create a regulatory framework based on quantitative indicators of the equipment quality. Qualimetry measured volume of metal removing allows setting the maximum possible productivity (quali-power) of metal cutting machinery, based on a small number of basic quality indicators contained in the machinery data sheets. It is essential that the quali-power of the machinery is an objective indicator of its quality, independent of the specific conditions of its operation at any given time. Hence the productivity criteria in metalworking cutting operations can be measured.
Investigation in fuel consumption of a hybrid and conventional vehicle
(2020) Šmigins, R.; Pīrs, V.; Berjoza, D.
During the last decade the introduction of more environmentally friendly technologies were raised more rapidly by the decline in the global fossil energy resources and the increased negative environmental impact of conventional vehicles. One of such technology is the hybrid, which is currently making the transition from conventional vehicle with internal combustion engine to an electric vehicle. At this time there exist a lot of offers of such vehicles from different manufacturers, but there do not exist many researches connected with real hybrid performance in different road cycles and conditions allowing evaluate its real economical performance. This research was realized with the aim to evaluate performance and fuel consumption of hybrid electric vehicle and its conventional internal combustion engine analogue in laboratory conditions. Tests were realized with two new Toyota Yaris vehicles in Alternative Fuels and Research Laboratory on chassis dynamometer MD-1750 using AVL KMA Mobile system. The results showed better adaptation of Toyota Yaris Hybrid to urban operation, demonstrating 21.3% lower fuel consumption than Toyota Yaris conventional gasoline vehicle, accordingly 7.29 and 8.84 L (100 km)-1.
Development of hemp hurd particleboards from formaldehyde-free resins
(2020) Alao, P.; Tobias, M.; Kallakas, H.; Poltimäe, T.; Kers, J.; Goljandin, D.
Low density of hemp hurd (Cannabis Sativa L), better end of life impact, performance comparable to wood chips and low energy requirement for cultivation make it a suitable alternative raw material for particleboards (Pb). However, due to concerns about sustainability and formaldehyde emissions, it is essential to develop the new bio-based resins from renewable resources. In this research, the mechanical and physical properties of Pb produced from hemp hurds (HH) and a variety of resins: Urea-formaldehyde (UF), formaldehyde-free acrylic resin (Acrodur®) and bio-based soy resin (Soyad™) were compared to those of wood particles (WP) bonded with UF. The results indicate that boards from HH are generally lighter than WP with a 5.6% variation between HH+UF and WP+UF. Hemp boards based on soy-resin showed higher tensile performance, with an average of 0.43 MPa compared to the 0.28 MPa and 0.24 MPa of (HH+UF) and (WP+UF) respectively. Nevertheless, thickness swelling (TS) of HH+UF (27%) was the least, while there was no significant difference in the water absorption (WA) compared to HH+Soyad4740, both were still lower than that of WP+UF. The overall outcome shows that bio-based soy resin can be a suitable alternative to UF as a binder in Pb production.
A control method for increasing the heat usage efficiency of nearly-zero-energy buildings with heat pumps
(2020) Pihlap, Heino; Annuk, Andres; Lehtonen, M.; Muiste, Siim; Tooming, Allan; Allik, Alo; Estonian University of Life Sciences. Institute of Technology. Chair of Energy Application Engineering
In the retrofitting of older buildings with central heating into nearly zero-energy buildings more and more air to water heat pumps are used. These heat pumps are normally connected to heating systems, producing heat only on demand. The greatest demand for heat occurs when the outside temperature and therefore the COP of the pump is lowest. Outside temperature varies during the day, meaning it is possible to save energy by producing and storing heat in a situation where the COP is higher. To determine the periods with higher COP values weather forecast data and COP curves are used. The data enables to rank and select time periods for heat production. This in conjunction with the heat demand curve of the building enables to create an operation schedule for the heat pump. The aim of the study is to develop heat pump control methods for renovated buildings to comply with nearly zero energy building codes. Dependant on the heat pump and weather conditions, up to 10 % of the electricity demand for heating can be decreased.

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