2018, Vol. 16, Special Issue 1

Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/5379

Sirvi

Nüüd näidatakse 1 - 20 38

Quality assessment of laser cladded HSS coatings with deep penetration into base material to obtain a smooth gradient of properties in coating-substrate interface
(2018) Ločs, S.; Boiko, I.
The present research is dedicated to the study of influence of coaxial laser cladding (CLC) process parameters onto values of alloying compo nents content in the coatings, morphology as well as the influence of post - cladding heat treatment on the quality and mechanical properties of coatings. The research is based on a hypothesis that applying of first layer of coatings onto steel substrate wit h keyhole in penetration allows achieving smooth gradient of properties of the coating - substrate system. As a result it may provide a smooth distribution of the internal residual stresses in interface as well as the better resistance to external stress dur ing cyclic load in tool operation processes: metal forming, stamping etc. Experimental work was carried out using CLC system, which consists of industrial robot Kuka and 1 kW IPG Yb - fiber laser, integrated to the coaxial powder supplying cladding head. The regularities of formation of High Speed Steel AISI М2 cladding coatings created by different regimes were studied by deposition onto EN 41Cr4 and C80U steel substrates. The quality of achieved coatings has been evaluated by examination of morphology of tr ansverse cross - sections, coatings geometrical features, elemental composition and microhardness distribution inside coatings. Additionally detailed assessment of coating thickness and content of alloying elements using statistical methods has been performe d. As a result of the research done the degree of influence of chosen CLC process parameters onto quality characteristics were estimated. The most appropriate cladding regime for used method was proposed.
Comparison of predicted and real parameters of PV systems in the Czech Republic and Spain
(2018) Olšan, T.; Soucase, B. M.; Libra, M.
This paper compares predicted performance by a simulation software for a given new constructed PV system of crystalline silicon technology located in Prague with 10 kWp peak power and a similar system in Spain. Simulation software used for the sake of this paper was publicly available PVGIS from the website of its creators, parameters were set to be the same like in the real PV system. The difference between the predicted and the real data was calculated and then discussed in the result section of this pape r. Suggestion how to increase the accuracy of the prediction by the simulation software is in the discussion part of this paper.
Detection reliability for passive infrared detectors in intrusion and hold-up alarm systems and their ergonomics
(2018) Hart, J.; Hartová, V.
Currently it is highly important for detectors to be able to achieve efficiency, reliability, and faultless operation, and to be ergonomic thanks to their assembly and being easy-to-fit. In the case of a proposal for the placement of detectors it is naturally important to determine position of the detector and the type of detector being used, but also to guarantee their capability to be able to detect anything when in use and their user and installation-friendliness. The problem of passive infrared (PIR) detectors affects a large proportion of intrusion and hold-up alarm systems (I&HAS). In a time of increasing property crime, it is highly important for PIR detector to actually be able to detect break-in attempts within the guarded area on a reliable basis and free of error. In the case of the installation of PIR detectors, it is naturally important not only to ensure correct installation, to gauge the external influences which may impact upon the detector and to ensure proper maintenance, but also to guarantee the capability of detection under more arduous conditions. The tests and comparisons which have been conducted examine both the normal operation of the PIR detectors and the ergonomics of these detectors. These tests are important both from an informative perspective and due to the opportunities to be able to develop potential counter-measures which could lead to their improvement.
Properties of local produced animal-fat based biodiesel and its blend with fossil fuel
(2018) Sirviö, K.; Heikkilä, S.; Help, R.; Niemi, S.; Hiltunen, E.
In the near future, more emphasis must be put on reducing greenhouse gas (GHG) emissions in road transportation, house heating, agricultural activities, marine transport etc. This study concentrated on the use of alternative fuels in engine - driven applicat ions of non - road machineries and decentralized energy production . Today, the engines are mainly designed for crude oil derived fuels and liquid renewable fuels are blended with crude oil based fuels to fulfill the requirements of renewable energy usage. Du e to the environmental reasons on one hand and to the agricultural needs, on the other hand , different blends of bio - and fossil fuels are becoming more popular. In Europe, the maximum FAME content in diesel fuel is 7 vol% according to the EN 590:2013 but higher percentages are also available and targeted around the world. For example in the United States, the 20% blend fraction is becoming more common. For these reasons, B20 fuels were chosen to be investigated in this study. Special emphasis was put on im proving blending issues since fuel blending may cause some operating risks. The main aim was to research widely the properties of animal - fat based methyl ester (AFME) and B20 fuel blend produced from it. AFME is a waste based fuel and produced in Ostroboth nia region, Finland. The aim was to find out in which engine applications the fuels are feasible and investigate if the fuels fit in the quality of automotive fuel Standards. According to the results, AFME is a feasible option to increase self - sufficient e ne rgy production in Ostrobothnia.
Capacitive frost depth indicator
(2018) Papez, V.; Papezova, S.
The depth of soil freezing , i.e., the depth at which water is frozen, is a significant factor in meteorology, as it affects many processes in agriculture, building, etc. Soil frost penetration is an important factor for overwintering organisms, but also for physical and chemical processes in soil, particularly for its mechanical properties. The de pth of freezing is normally determined directly, i.e. mechanically, using a special soil freezing meter, i.e., frost - depth indicator, according to the process of water freezing in the probe. Another method lies in determining the soil temperature by the in terpolation of the curves from the graph, as measured by soil thermometers according to the change in the resistivity of soil or water, when frozen. The principle of the frost - depth indicator function is to evaluate the temperature dependence of water perm ittivity, which decreases, when water is frozen, from ε r ~ 87 at 1 °C to ε r ~ 3.2 at - 1 °C , typical for ice. The water permittivity is evaluated by a measuring capacitor, which is adapted into the shape of the frost depth indicator probe, whose dielectric is deionized water. During freezing, the capacity is reduced in this area. The capacity of the partially frozen probe is directly proportional to the length of its non - frozen section. The measuring capacitor is a part of the resonant circuit of the oscilla tor. The frequency of the oscillator varies with the capacity of the probe and is further evaluated. The achievable measurement accuracy is approximately 2% for the probe of a 1m length and in direct evaluation by an autonomous counter. For the computer ev aluation, with the possibility to compensate the probe non - linearity, the measurement accuracy is approximately 0.5%.
Stabilization of persistent organic pollutants (POP) in flue gases in a biological waste incinerating facility
(2018) Jirsa, P.; Malaťák, J.
The article focuses on a technology of flue gases stabilization in biological and hospital waste incinerating facility. Hazardous particles and compounds formed in flue gas during the process of thermal waste degradation need to be stabilized according to an enacted legislation. The aim of the research is to examine technological process of polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDD/F) elimination in flue gas. PCDD/F is group of persistent organic pollutants which are resistant to environmental degradation and are highly toxic for the environment in very small amounts. Experiments were performed in semi operation hospital waste incinerating plant with heating power 1.5 MW and capacity 250 kg h - 1 of incinerating material. It was observed that formation of PCDD/F exponentially grows with increasing concentration of chlorides in the flue gas, but formation varies based on type of congener. The highest concentration was measured for HxDF, 17,522 pg Nm - 3 and HpDF, 16,334 pg Nm - 3 at chloride concentration of 867 mg Nm - 3 . However, concentration of PCDD congeners didn ́t exceeded 4,000 pg Nm - 3 for the same level of chlorides in flue gas. Two types of activated carbon Chezacarb and NORIT were tested for capability to stabilize PCDD/F in flue gas. Results show that refining effect for both sorbent are very similar. It was observed that 0.1 g of activated carbon should be applied per 1 Nm 3 of flue gas in regard to reduce 3 – 4 ng Nm - 3 PCDD/F under required emission limit.
Investigation into the performance characteristics of electric automobiles by means of a data logger
(2018) Berjoza, D.; Pīrs, V.; Jurgena, I.
Fossil fuel deposits are constrained in the world. Various alternative energy sources are introduced in vehicles to limit the depletion of fossil fuel reserves and to reduce environmental pollution. One of the alternative energy sources is electricity. Th e use of electric automobiles has begun in the Baltic States too, yet accurate performance parameters of the automobiles, which could sometimes differ from the technical characteristics specified, are not always known. Road testing an electric automobile w as performed using a data logger that recorded the battery’s voltage, current, temperature and the automobile’s speed. These parameters allowed computing changes in the electric automobile’s power output under various driving regimes, e.g. acceleration or braking. Road testing the electric automobile was done under two driving regimes – urban and non - urban – on a certain route. The experiment represented a full cycle road test, with the batteries fully charged, that lasted until the batteries were discharge d to a minimum level, which was limited by the battery management system (BMS). The experiment identified the maximum current as well as the effectiveness of the regenerative braking system.
Influence of the road profile in different geographical areas of the Czech Republic to the operational parameters of the electric vehicle
(2018) Marčev, D.; Kotek, M.
The aim of this paper is to compare the operating parameters of the full - electric vehicle VW e - up! operated in two significantly different geographic areas of the Czech Republic. The first tested area was the lowland area in the v icinity of municipality Mělník; the second area was a hilly area near the municipality of Ústí nad Labem with frequent and very sharp altitude changes. During measurement, the operating parameters of the battery (voltage, level) and electric motor (instant aneous voltage and current) were recorded. The results show a surprisingly small difference in vehicle tank range in both compared regions because the recuperation in the hilly area was used very often. It is possible to conclude that these electric vehicl es can be used for everyday commuting under conditions of different geographical areas.
A comparative case study of the efficiency of collection systems for paper and biodegradable municipal solid waste
(2018) Chotovinský, O.; Altmann, V.
The need to increase municipal solid waste recycling rates has led to the study and analysis of recycling schemes from the perspective of the technical issues that may be involved. This paper compares two waste collection systems, which are operating in th e Vysočina region of the Czech Republic: a municipal solid waste collection system for paper (including cardboard) and a biodegradable municipal solid waste collection system. Both collection systems were introduced at different times to cover one selected urban area. The emphasis has been placed on an evaluation of the development of individual, separate collections between 2014 and 2016. Analysis of the technological operation and performance of the collections are observed and evaluated by measuring a ra nge of waste collection system indicators. Efficiency levels, especially when it comes to separate collections of both types of municipal solid waste, are compared to their relative representation in the remaining bulk of municipal solid waste. The changes in representation of these types of waste against those in the rest of the municipal solid waste shows which collection systems are more successful from the perspective of the implementation of the directive which covers landfill usage. The results also d escribe why systems could be more successful within the view of well - chosen or inappropriately - selected technological parameters for materials separation. The possibly statistically significant impact of paper waste production in terms of the relative amou nt of paper waste across the rest of the municipal solid waste has also been shown.
The operational parameters and emissions of portable generator after long-term operation on n-butanol
(2018) Pexa, M.; Čedík, J.; Peterka, B.; Holůbek, M.
The utilization of biofuels in spark ignition and compression ignition engines is the trend of the recent time. The great expectations are inserted into n - butanol as a fuel, especially for spark ignition engines. The short time use of n - butanol in the SI (spark ignition) combustion engine does not make a big problem (start of the cold engine, change of the air - fuel ratio). The purpose of this contribution is the effect of long - term use of n - butanol as a fuel for SI engine. For this purpose the small portable generator was used. The harmful emissions, fuel consumption and power of the generator was measured then the generator was operated for 300 hours on 100% n - butanol with 80% of nominal load and the measurement was repeated. The g enerator was loaded with adjustable electrical resistance. As a reference fuel the petrol BA 95 with no bio - component was used. During the operation on n - butanol no technical problems occurred with the generator. After 300 hours of operation on n - butanol t he performance parameters slightly decreased with little impact on production of harmful emissions components.
An assessment of stratification of exhaust gases from gasoline and diesel engine
(2018) Birkavs, A.; Smigins, R.
Research the aim of which was to find out stratification of main exhaust components outside the tailpipe of the vehicle was realized in Alternative Fuels Research Laboratory of Latvia University of Agriculture using two commercially produced testing vehicl es (diesel and gasoline) and exhaust gas analytical system AVL SESAM FTIR. Additionally there was created a gas testing camera allowing to measure concentration of exhaust gas components in different heights and windless conditions. Regulated and unregulat ed emissions from gasoline and diesel engines were measured and discussed. Results obtained during the measurements showed main stratification of toxic components from both engine types from 0.6 to 1.1 m from the ground making a risk to get some health pr oblems by inhalation, especially for children. Main components (NOx, CO, HC) of exhaust gases of gasoline engines stay in the air for about 15 minutes in height of 1.0 m from the ground level, while methane and acetylene stay in the air for a 15 minutes in height of 0.6 m from the ground level.
Plantograf V18 – new construction and properties
(2018) Koder, P.; Novák, V.; Ryzhenko, V.; Hrubý, D.; Volf, J.; Novák, D.
The article describes Plantograf V18, a planar tactile transducer, which converts the applied pressure into electric signal and enables a graphical presentation of the measured data; the new version V18 comes with some significant improvements and modifications. The device may be used ev erywhere where the pressure distribution between an object and surface is to be determined, e.g. in medicine or automotive industry. The article contains the detailed description of the transducer design and its electronic control circuits, as well as the yet unpublished measurements of pressure sensitivity with 3.5 mm electrodes.
Diagnostics of hydraulic fluids used in aviation
(2018) Obergruber, M.; Hönig, V.; Procházka, P.; Táborský, J.
Diagnostics is a maintenance industry that monitors performance, parameters, and follow – up. Diagnosing hydraulic fluids means comparing the parameters of the used hydr aulic fluid sample to the parameters of the clean fluid. It is also essentia l to monitor the limit values either by the aircraft manufacturer or by the manufacturer of the hydraulic fluid. This means that the manufacturer recommends the limitations of the liquid parameters. The measurements of the fluid samples give an overview of the liquid quality. Most businesses focus on so – called proactive maintenance. The main senses and objectives of proactive maintenance are: lubricant sample analysis, lubricant sta tus, machine status, next step recommendation, database saving and trend analysis. This article focuses on the quality of hydraulic fluid focused in aviation. The aim of the article was to determine the properties of the hydraulic fluid used in the A320 ai rcraft family, determine the interval of its exchange. Monitoring the state of the hydraulic fluid could contribute to the timely detection of the problem, thus avoiding a failure of the device or the system as a whole. The tracking proposal is an integral part of this article.
Exhaust particle size distributions of a non-road diesel engine in an endurance test
(2018) Ovaska, T.; Niemi, S.; Katila, T.; Nilsson, O.
The main objective of this study was to find out how th e non - road diesel engine running period of 500 hours affects the exhaust particle size distribution. By means of an engine exhaust particle sizer (EEPS), particle number was measured before the endurance test and after 250 and 500 hours of engine operation . The size distributions were determined at full and 75% loads both at rated and at intermediate speeds. The soot, gaseous emissions and the basic engine performance were also determined and lubricating oil was analysed a few times during the running perio d. A blend of low - sulphur fossil diesel and soybean methyl ester (B20) was used as fuel in the 4 - cylinder, turbocharged, intercooled engine which was equipped with a diesel oxidation catalyst (DOC) and a selective catalytic reduction (SCR) system. All em issions were measured downstream the catalysts. During the 500 hours of operation, the particle number increased considerably within an approximate size range of 7 to 30 nm . Between the initial and final measurements, no notable differences were observed i n the particle number emissions within a particle size range of 50 to 200 nm . The copper content of lubricating oil also increased significantly during the 500 hours’ experiment. One possible reason for the substantial increase in the nucleation mode parti cle number was assumed to be copper, which is one of the metallic elements originating from engine wear. The engine efficiency was almost equal, and the differences both in smoke and hydrocarbon emission were negligible throughout the 500 hours’ experiment.
Effect of rubber powder from waste tyre rubbers on mechanical properties of one-component polyurethane putty
(2018) Tichý, M.; Müller, M.; Valášek, P.; Miturska, I.
The utilization of adhesives in technical practice is varied. Adhesives serve for a creation of strength bonds on the one hand, and on the other hand e.g. for cementing. The aim of the research is a modification of one - component polyurethane putty RPS 45 used in automotive industry to increase strength properties in an adhesive bond. An i nteraction between a filler in the form of rubber powder micro - particles and one - component polyurethane adhesive was investigated by means of SEM analysis. Sealing is a primary property of this putty. Sealing putties usually reach very small strength which can be increased by an admixture of the filler. In order to keep elastic properties, micro - particles of the rubber powder gained from tyre recycling process were used as the filler. An aspect of a loading speed of the adhesive bond is essential at the pra ctical application at which the adhesive bond can be failed in adhesive or cohesive layers. The adhesive bond can be perceived in terms of its function as a complex of three layers, i.e. an adhesive bonded material, the interaction between the adhesive and the adhesive bonded material and the adhesive layer itself. There are often states in the practices when the adhesive bonds are exposed to the loading which can be either a static or a dynamic one. That is why the research is focused not only on the evalu ation of the influence of the modification of the one - component polyurethane adhesive, but also on the influence of the loading speed of the adhesive bond. Tested speeds set on a universal testing machine Zwick/Roell Z150 were 2, 50 and 100 mm min - 1 . The r esults of mechanical tests proved a positive influence of the filler on the strength σ m higher by 42.68 ± 6.96% and the elongation at break ε b higher by 12.2 ± 20.95%. On the contrary, the stress at yield σ y was decreased.
Preliminary conclusions on application of ultrasonic sensors in evaluation of distribution and depth of ruts in forest thinning
(2018) Pužuls, K.; Štāls, T.; Zimelis, A.; Lazdiņš, A.
The scope of the study is to elaborate equipment for measurement of ruts during log forwarding. The system is supposed to be used in practical forestry to replace manual measurement of length of deep ruts and to provide spatially explicated information on soil bearing capacity, which can be used in planning of forest operations. A set of 4 pairs of ultra sonic sensors were installed on front and rear bunks to measure distance to the ground at 90 o angle (in front and behind the wheels in each side of forwarder) and at certain angle to measure distance to the ground outside strip - road. Measurement data are s ent to the logger, where they are stored in .csv files. Wired connection between the sensors and the logger was used in earlier version, but later replaced with wireless connection. Depth of rut is calculated using formula for calculation of length of cath etus of a right - angled triangle. Data processing in spreadsheet includes initial identification of error values and calculation of depth of ruts. Further spatial data analysis is done in GIS software. According to the study results ultrasonic sensors provi des sufficient accuracy to characterize depth of ruts in 1...5 m long segments of strip - roads, including dynamic data on depth and length of ruts after each pass. However, the accuracy is insufficient to compare measurements from sensors mounted on front a nd rear bunks, as well as on left and right side of machine, therefore it is enough to have 2 pairs on sensors on rear bunks.
Testing of ISM band at remotes for unlocking vehicles
(2018) Hart, J.; Hartová, V.
Every modern car has a remote control for wireless unlocking. Wireless drivers for unlocking the vehicle using frequency in the ISM bands. ISM bands are unlicensed bands. They are usually used for industrial, medical and scientific purposes. The question is whether wireless transmission parameters are sufficient and do not violate defined range of ISM band. Another important aspect is the security of the wireless transmissions and any other signal interference. The problem of interference plays an important role in ensuring the quality and safety of wireless communications, especially when wireless networks can be found everywhere. The issues of remote control vehicles is very important due to the resulting security of a guarded vehicle. One of the major risks that may occur are data transmission that the signal is blocked by another signal and the end user does not notice. In this case, does not lock the vehicle nor ensuring its securing security system. Tests which were performed accurately determined the bandwidth of broadcast remote control for each vehicle. Vehicles for which the tests were conducted are standard vehicles used to frequent occurrence. These are the following types: Alfa Romeo, Hyundai, Mercedes, Škoda and Toyota. Subsequently, the analysis was performed of transmission compared with standard broadcast of jammers. All test drivers worked in the band ISM433. These tests clearly demonstrated that not every manufacturer strictly observes ranges of ISM band. This may affect traffic on surrounding licensed bands.
Battery capacity drop during operation
(2018) Papezova, S.; Papez, V.
A lithium - iron - phosphate ( LiFePO 4 ) battery is nowadays considered one of the best types of batteries. The paper deals with the evaluation of the drop in their capacity during operation. Based on the physical analysis of charging an d discharging processes, a mathematical model of the battery capacity has been developed during its lifetime. The decrease in capacity during battery operation is evaluated according to the loss of active material, which gradually diminishes due to a numbe r of different processes. The analysis of the loss of the active material is carried out, in particular, according to the depth of discharge, battery temperature, charging and discharging time, including the time when the battery is out of service. The tes ts were performed on the Winston Battery, Calb, Thunder Sky and Sinopoly batteries by cyclic discharging and charging at the 50%, 90% or 100% depth of discharge. Their real parameters were determined, compared to the model parameters and the parameters specified by the manufacturers and suppliers. Two automated systems were used for testing. During the test, in the tested battery with several cells, charging and discharging by a constant current were carried out automatically. Operating parameters of the te sted battery were continuously scanned, recorded and evaluated by the control computer. The capacity curves during the battery operation, determined by the type of models, were compared with the results of long - term real battery tests.
Kinematic viscosity studies for medium-speed CI engine fuel blends
(2018) Sirviö, K.; Niemi, S.; Help, R.; Heikkilä, S.; Hiltunen, E.
Engine - driven power plants, run by diesel fuel or gas, will be needed for peaking power to keep the electricity grids stable when the production of renewable electricity, e.g. utilizing wind or solar power, is increased. The choice of the alternative, renewable fuels for engine - driven power plants and marine applications is at the moment quite narrow. The amount of renewables of all liquid fuels is at present less than 2%. Biodiesels, FAMEs, have been studied for long time and apparently, despite of the problems they may have, they are still in the great interest. One import ant increment to the category of alternatives is fuels that are produced from e.g. oil wastes, i.e., recycled fuels. They are not renewable, but recycling of potential energy raw materials is still one step forward in increasing the suitable and more susta inable options. To utilize the blends in medium - speed engines for power production, accurate knowledge of the physical and chemical properties of fuel blends is very important for the optimization of engine performance. The determination of the fuel kinema tic viscosity is needed to create proper fuel atomization. The injection viscosity affects directly the combustion efficiency and the engine power. Consequently, this study focused on measuring kinematic viscosity curves for seven fuel blends, as well as t he neat fuels used for blending. The temperature range was 10 – 90 °C. The fuels used for blending were rapeseed methyl ester, animal - fat based methyl ester, hydro - treated vegetable oil, light fuel oil and marine gas oil produced from recycled lubricating oi ls.
Development and testing results of IoT based air temperature and humidity measurement system for industrial greenhouse
(2018) Avotins, A.; Apse-Apsitis, P.; Bicāns, J.; Gruduls, J.
In dustrial greenhouse control systems are changing and getting new capabilities, due to the evolution of the Internet of Things (IoT) technologies, allowing wirelessly integrate various sensor technologies and create a cloud - based database and analytic solut ions. Greenhouse systems typically are controlled by consuming single temperature and humidity measurement unit data (treated as an average value), this raises a question about the precision of such approach for application in a large industrial greenhouse . In this article IoT based temperature and humidity measurement system uMOL architecture is described and first measurement results of multi - point data collection with high resolution compared to existing single - point measurements.

Sirvi

Sirvi 2018, Vol. 16, Special Issue 1 Kuupäev järgi

Tulemused lehekülje kohta

Sorteerimisvalikud