Volume 17 (2019)
  Special Issue I

Full text of the journal: Volume 17 Special Issue 1

Contents


Pages

913–922 M. Baidakova, V. Sitnikova, M. Uspenskaya, R. Olekhnovich and M. Kremenevskaya
Polymer acrylic hydrogels with protein filler: Synthesis and characterization
Abstract |

Polymer acrylic hydrogels with protein filler: Synthesis and characterization

M. Baidakova*, V. Sitnikova, M. Uspenskaya, R. Olekhnovich and M. Kremenevskaya

International Research Center for Bioengineering, ITMO University, 49 Kronverksky ave., RU197101 St. Petersburg, Russia
*Correspondence: mvbaidakova@yandex.ru

Abstract:

The water-retention hydrogel composites were synthesized by the free-radical polymerization depending on the order of addition filler of the protein hydrolysate. As the filler was used protein hydrolysate, ‘Biostim’, obtained by processing cattle hides. The influence of gelation time on the synthesis parameters of hydrogel compositions was investigated. It is found that the gelation time of the sample without filler is 2–2.5 times longer than filled of hydrogel compositions. The structural characteristics of polymer composition by TGA, DSC and atomic force microscopy were determined. FTIR spectra found decrease in the intensity of vibrations of (-COO-) groups, indicating about additional ionic interactions. Decrease the beginning evaporation temperature of polymer composites with increase concentration of protein filler, indicating the destruction of the ordered structure of the polymer material revealed by thermogravimetric analysis (TGA). The influence of various media, such as distilled water, saline solution, and buffer solutions at differents pH on the swelling behavior of hydrogels was also assessed. Maximum swelling capacity showed sample prepared with order of addition filler at the end of synthesis (Scheme I). The kinetics of the release protein hydrolysate from the polymer matrix was measurement by spectrophotometric method. The synthesized hydrogel composites with protein hydrolysate and improved physicochemical properties are of practical interest as water-retaining materials for increasing of crop the yield in agricultural.

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923–934 G. Bambi, P.F.P Ferraz, G.A.S. Ferraz, P. Pellegrini and H. Di Giovannantonio
Measure of thermal transmittance of two different infill wall built with bamboo cultivated in Tuscany
Abstract |

Measure of thermal transmittance of two different infill wall built with bamboo cultivated in Tuscany

G. Bambi¹, P.F.P Ferraz², G.A.S. Ferraz², P. Pellegrini¹ and H. Di Giovannantonio¹

¹University of Florence, Department of Agriculture, Food, Environment and Forestry, Via San Bonaventura 13, IT50145 Firenze, Italy
²University Federal of Lavras, Department of Engineering, Federal University of Lavras, BR37200-000 Lavras -Minas Gerais, Brasil
*Correspondence: gianluca.bambi@unifi.it

Abstract:

Bamboo is used in different scenarios of application, its physical and mechanical characteristics guarantee a high flexibility of use especially in the buildings constructions. The experience gained in civil constructions demonstrates that bamboo can be considered a sustainable material able to replace wood in many constructive elements with structural functions. The applications of bamboo aimed at carrying out structural functions are thoroughly studied. For this reason the present research focuses on the thermal insulation performance. To ensure an approach focused on the sustainability of potential exploitation, the research examined only local material coming from three bamboo fields located in the Tuscany region (Italy). The material harvested and suitably treated was utilized for the realization of two different kind of wall, undergone later to experimental tests in compliance with the ISO 9869 standard for the calculation of the transmittance values. The measure of transmittance enabled to know the characteristics of thermal conduction of bamboo walls. The first wall was made of cut throw longitudinal axis bamboo culms; the second one was made of cut throw longitudinal axis bamboo culms coated in internal face with a sustainable mortar. The test was carried out using insulating thermal box with internal temperature under control.
The calculation of the transmittance in place was compared with the images captured by thermal camera. Thermal imagine allowed to highlight the behaviour of the material subjected to a thermal stress induced by the experimental test.

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935–944 D. Berjoza, V. Pirs and I. Jurgena
Possibilities to identify defective electric automobile batteries
Abstract |

Possibilities to identify defective electric automobile batteries

D. Berjoza¹, V. Pirs¹ and I. Jurgena²

¹Latvia University of Life Sciences and Technologies, Faculty of Engineering,
Motor Vehicle Institute, J. Cakstes 5, LV–3001 Jelgava, Latvia
²Latvia University of Life Sciences and Technologies, Faculty of Economics and Social
Development, Institute of Business and Management Science, Svetes street 18,
LV–3001 Jelgava, Latvia
*Correspondence: dainis.berjoza@llu.lv; inara.jurgena@llu.lv

Abstract:

A pack of batteries is one of the most important and expensive assemblies for an electric vehicle. A pack of batteries is comprised of several batteries connected in series. The number of the batteries connected depends on the operating voltage of the vehicle’s on-board system as well as on the individual characteristics of the batteries used, e.g. the operating voltage of a single cell. One or several cells of a pack of batteries could be damaged if improperly exploiting an electric vehicleexcessively discharging the batteries or overloading the electric vehicle. If a self-converted vehicle does not use an intellectual BMS (battery management system) that can identify and register voltage drop for any individual cell in the high-load regime, e.g. when accelerating, it is difficult to identify and change the cells damaged. In case a cell does not demonstrate a complete failure, it is almost impossible to identify a defect in any regime other than the load regime.

The research developed and compared three different methods for identifying defective battery cells. The methods were approbated on a converted Renault Clio. The experiment involved making voltage  measurements in road tests, running the electric vehicle on a roll test bench and making voltage measurements of maximally discharged batteries in the no-load regime. A comparison of the measurement results revealed that the measurements made in the road tests were the most accurate and useful. After the  experiment, the defective battery cells were replaced, thereby restoring the performance of the battery pack.

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945–956 D.V. Cao and P. Kic
An analysis of influences of blinds and solar radiation on microclimate in office rooms during summer days: a pilot study
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An analysis of influences of blinds and solar radiation on microclimate in office rooms during summer days: a pilot study

D.V. Cao* and P. Kic

Czech University of Life Sciences Prague, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 21, Czech Republic
*Correspondence: caodoan2006@gmail.com

Abstract:

Windows are the only part of a building that can directly penetrate the solar radiation into the occupied space and thus the shading devices are needed to control the solar penetration. In the office buildings, they usually use external blinds and internal blinds to reduce heat gains during summer caused by sunlight as well as solar radiation. Therefore, these blinds are main part to maintain thermal comfort for office workers. The aim of this paper is to present results of measurements in four big office rooms in different situations of blinds application. Then, the influence of the internal and external blinds on the internal microclimate conditions inside the large offices during the hot summer days with high solar radiation will be evaluate. The offices floor area is from 43.3 m2 to 59.5 m2 and height 2.8 m. The experiments in this research were focused on measurement and evaluation of globe temperature, indoor air temperature and relative humidity at level of working place during several hot summer days. Comparison of the results of short-term measurements in a room with open blinds and closed blinds has shown the influence of the blinds on the reduction of indoor temperature. More significant was the effect of external aluminium blinds. Solar energies passing through the windows into the interior were 3,476 W without blind and 305 W in case of aluminium venetian external blinds. When the maximum outside temperature was 29.9 °C and office workers used blinds with natural ventilation, the maximum air temperatures in four rooms were from 27.2 °C to 28.5 °C, which exceeded maximum recommended temperature (28 °C). The external aluminium venetian blinds and internal fabric vertical blinds did not maintain thermal comfort inside the offices during all summer days, but it can help in reduction of energy consumption for air-conditioning.

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957–973 J. Čedík, M. Pexa, D. Mader and R. Pražan
Combustion characteristics of compression ignition engine operating on rapeseed oil-diesel fuel blends
Abstract |

Combustion characteristics of compression ignition engine operating on rapeseed oil-diesel fuel blends

J. Čedík¹*, M. Pexa¹, D. Mader¹ and R. Pražan²

¹Czech University of Life Sciences Prague, Faculty of Engineering, Department for Quality and Dependability of Machines, Kamýcká 129, CZ165 21 Prague 6, Czech Republic
²Research Institute of Agriculture Engineering, Drnovská 507, CZ161 01 Prague 6, Czech Republic
*Correspondence: cedikj@tf.czu.cz

Abstract:

The effect of biofuels on the operational parameters of the combustion engines, such as performance parameters or emission production, are monitored often. These changes are, however, based on the effect of biofuels on the course of combustion pressure inside the combustion chamber. The contribution deals with the effect of rapeseed oil-diesel fuel blends on the combustion characteristics of turbocharged compression ignition engine. The course of cylinder pressure was monitored and analysed and heat release rate was calculated. The brake specific fuel consumption, indicated and brake thermal efficiency were calculated and evaluated, in-cylinder temperature and ignition delay were also evaluated. As a test fuels a 5% and 20% concentrations of rapeseed oil in diesel fuel were selected while 100% diesel fuel was used as a reference. Turbocharged CI engine Zetor 1204 located in the tractor Zetor Forterra 8642 was used for measurement. During measurement the rotation speed of the engine was kept constant at approx. 1,950 min-1 and the load of the engine was selected at approx. 20, 60, 80 and 100%. The results showed decreased cylinder peak pressure, decreased intensity of heat release rate and earlier end of combustion in all tested loads for both tested fuel blends in comparison with diesel fuel, while the lowest peak cylinder pressure was reached using fuel with 5% rapeseed oil. Fuel with 5% rapeseed oil also showed highest indicated efficiency. Ignition delay was found shorter with both of the blended fuels in comparison with diesel fuel.

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974–981 O. Chernikova, Yu. Mazhayskiy and L. Ampleeva
Selenium in nanosized form as an alternative to microfertilizers
Abstract |
Full text PDF (984 KB)

Selenium in nanosized form as an alternative to microfertilizers

O. Chernikova¹, Yu. Mazhayskiy¹ and L. Ampleeva²

¹Academy of law management of the federal penal service of Russia, RU390036 Ryazan, Sennaya street 1, Russian Federation
²Ryazan State Agrotechnological University named after P.A. Kostychev, RU390044 Ryazan, Kostycheva street 1, Russian Federation
*Correspondence: chernikova_olga@inbox.ru

Abstract:

Nowadays, it is an obvious fact that it is necessary to look for new approaches to agriculture, which would ensure the maximum reduction in the dependence of the volumes and quality of the crop on external factors. The use of nanopreparations in crop production is the most promising. The development of new technologies and techniques using nanomaterials, which would ensure high yields and quality of potato products, is relevant and has great practical importance. The research in recent years has established the important role of selenium in the regulation of plant activity.The purpose of this work was to research the effect of selenium nanoparticles and selenium in the form of micronutrient fertilizers on early-maturing varieties of potatoes for table use: adaptive capacity and nutritional value. Selenium nanopowder in the form of a solution contained the optimum nanoselenium concentration applied–0.13 g per hectare seeding rate. The potato tubers were soaked in distilled water 30 minutes before seeding. The treatment of potato tubers with selenium micronutrient, the dose of which amounted to 400 g per 1 hectare, was also carried out before planting. The soil preparation and agrotechnology cultivation generally accepted in the Ryazan region.The research results showed that presowing treatment of potato tubers with selenium nanopreparation had the most favorable effect on the adaptive capacity of plants (heat resistance, water-holding properties), as well as on yield increase, than treatment of tubers with selenium in the form of microfertilizer. The use of Se nanoparticles leads to an increase in the protein and vitamin C content. The Udacha potato variety showed great responsiveness to the entering of various forms of selenium in comparison with others. The use of selenium in the form of microfertilizer leads to an increase in the accumulation of starch and dry matter. These figures were the highest in potato tubers of the Zhukovskiy Ranniy variety.

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982–986 M-Q. Dang, J. Šafránková, M. Libra, V. Poulek, P. Kouřím and J. Sedláček
Autonomous photovoltaic system for night-time lighting in the stable
Abstract |

Autonomous photovoltaic system for night-time lighting in the stable

M-Q. Dang, J. Šafránková, M. Libra, V. Poulek, P. Kouřím and J. Sedláček

Czech University of Life Sciences Prague, Kamycka 129, CZ16521 Prague, Czech Republic
*Correspondence: janicka.safrankova@gmail.com

Abstract:

Autonomous photovoltaic (PV) systems are suitable, for example, for powering various appliances or scientific instruments in the field, for automatic data collection, for signaling, etc. At the Czech University of Life Sciences Prague, we have designed an experimental autonomous PV system designed for night-time lighting for orientating in a stable for horses. The article describes the construction of a PV system with a PV panel rated at 170 Wp, with a lead-acid accumulator and a 1,5 W LED light source. The data collection was automated. The data evaluation shows that during the whole year, the PV system has been recharged and there was no lighting failure. The paper also presents important measured characteristics.

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987–992 J. Hart and J. Bradna
Suitability of 2.4 GHz and 5 GHz wireless communications in production processes
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Suitability of 2.4 GHz and 5 GHz wireless communications in production processes

J. Hart* and J. Bradna

Czech University of Life Sciences Prague, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 00 Prague, Czech Republic
*Correspondence: janhart77@gmail.com

Abstract:

Today, it is increasingly modern to use wireless transmissions in production. It is possible to send information messages, control messages and it is often possible to access the technologies as IoT (the Internet of Things). The aim of this work was to find out which of the selected Wi-Fi frequencies is more suitable for use in syrup processing equipment. The evaluation was performed on the basis of attenuation and download speed at each frequency (2.4 GHz and 5 GHz bandwidth). These frequencies have been chosen due to their massive deployment for wi-fi networks that currently dominate wireless communications. Measurements were made downloading files on different frequency bands. Mean and maximum data throughput and signal strengths were also measured. By measuring, it has been found that when using 2.4 GHz wireless Wi-Fi technology, you can very often encounter strong interference effects. Despite the theoretically worse 5 GHz frequency spread, you can achieve up to 30% better data throughput on average. The results show the suitability of 2.4 and 5 GHz Wi-Fi technology. The main finding is that, despite the worse frequency spread of 5 GHz, it is more appropriate. Not only due to speed but also in the future due to better transmission capacities and future channel expansion.

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993–1000 V. Hartová, M. Kotek, J. Hart and Š. Pícha
Reliability of parking assistants depending on the material of detected obstacles
Abstract |
Full text PDF (822 KB)

Reliability of parking assistants depending on the material of detected obstacles

V. Hartová¹, M. Kotek¹, J. Hart² and Š. Pícha¹

¹Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Vehicles and Ground Transport, Kamýcká 129, CZ165 00 Prague, Czech Republic
²Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Technological Equipment of Buildings, Kamýcká 129, CZ165 00 Prague, Czech Republic
*Correspondence: nidlova@tf.czu.cz

Abstract:

Today’s modern vehicles are equipped with a range of assistance systems to enhance road safety. The standard equipment of most cars are parking assistants. It turns out that not always sensors can reliably detect the obstacle on the travel path of the vehicle. The aim of the paper is to determine the reliability of the parking sensors depending on the material of the obstacle detected. The original parking assistants of Škoda Rapid, Škoda Octavia II, and Škoda Superb have been tested in laboratory conditions using obstacles made of various materials (glass, mirror, plastic, metal, cardboard …) located at distance of 100 cm from the vehicle. Distance values of the original sets of parking assistants were measured during the measurement from onboard diagnostic vehicle using diagnostic kit VAG-COM. The real distance was checked using a calibrated gauge. The results of the research show, that original sets of parking assistants achieve significantly more accurate results with a wider coverage of the space being scanned. Material composition of obstacles has a great influence on the reliability of parking systems. Not every material can respond properly to parking sensors.

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1001–1012 M. Holúbek, M. Pexa, J. Čedík and D. Mader
Effect of long-term operation of combustion engine running on n-butanol – rapeseed oil – diesel fuel blend
Abstract |

Effect of long-term operation of combustion engine running on n-butanol – rapeseed oil – diesel fuel blend

M. Holúbek*, M. Pexa, J. Čedík and D. Mader

Czech University of Life Sciences Prague, Faculty of Engineering, Department for Quality and Dependability of Machines, Kamýcká 129, CZ165 21, Prague 6, Czech Republic
*Correspondence: holubekm@tf.czu.cz

Abstract:

The short time use of biofuels in compression ignition engines is being studied by many authors. However, in many cases the real long–term operation of the engine on biofuels may cause problems. The article deals with the operation parameters of the combustion engine, fuelled by n-butanol – rapeseed oil – diesel fuel blend, during 70 hours operation in total. Two brand new diesel power generators Kipor KDE 6500 with output power of 4.6 kW were used for certain testing. The first generator was operated on 100% diesel fuel and it was used as a reference and the second generator was operated on experimental fuel containing 10% n-butanol – 20% rapeseed oil – 70% diesel fuel blend. The generators were equipped with single cylinder compression ignition engine Kipor KM 186 with the rated power of 5.7 kW. For the first 10 operating hours approx. 40% load was applied. Then, the generators worked for another 60 operating hours with approx. 70% load. The harmful emissions, smoke, fuel consumption and the amount of produced particles were also measured after 10 hours run-in period and then after another 60 hours of operation. Consequently, the results were compared. Measurements were carried out at gradually increasing electric power output, approx. 14%, 28%, 42%, 56%, 68%, 82% and 95% (in results can be found in Watts). Emission analyser and opacimeter BrainBee and Engine Exhaust Particle Sizer TSI were used for the measurements. The results showed increased production of emission of the engine running on fuel blend after 70 hours of operation. On the other hand, engine which operated on standard diesel reached lower fuel consumption. After 70 hours the blended fuel tended to produce more particles in comparison with diesel fuel.

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1013–1022 T. Jehlička and J. Sander
Separation of dust particles in the low-pressure pneumatic conveying system
Abstract |
Full text PDF (825 KB)

Separation of dust particles in the low-pressure pneumatic conveying system

T. Jehlička* and J. Sander

Czech University of Life Sciences Prague, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 21 Prague 6 – Suchdol, Czech Republic
*Correspondence: jehlickat@tf.czu.cz

Abstract:

This paper focuses on the possibility of separation of dust particle created as a by-product of technological processing of composite materials. The aim was to design and verify technology for the separation of dust particles from polydisperse granular mixtures, which are created by physical-mechanical processes of materials processing (crushing, sorting, machining or surface treatment of products such as grinding or polishing the surface). Under experimental conditions, a low-pressure pneumatic conveying system was designed and tested in operation, supplemented by a powerful electrostatic dust particles separation system. The entry requirement was to design a system that would be able to work with high separation efficiency using low-pressure suction. The designed separation conveying device consists of three parts: the conveyance section for the grain material suction and conveying, the coarse grain share cyclone separator and the electrostatic precipitator of the dust particles released from the air flow. Operational capacity of the proposed technology was verified by evaluating the separation efficiency of processing the polydisperse granular mixture resulting from the crushing of laser printer toner cartridges. These contain toner powder residues, which are the source of composite dust particles. The separation efficiency of the system was monitored according to the set pressure of the air in front of the electrostatic separator. Evaluation of the results thus obtained confirmed the operational reliability of the system at low-pressure operation and the high separation efficiency of the electrostatic separator under the set operation conditions.

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1023–1032 M. Jemeljanova, R. Ozola and M. Klavins
Physical-chemical properties and possible applications of clay minerals and humic acid composite materials
Abstract |

Physical-chemical properties and possible applications of clay minerals and humic acid composite materials

M. Jemeljanova*, R. Ozola and M. Klavins

Department of Environmental Science, University of Latvia, Raina Blvd. 19, LV-1586 Riga, Latvia
*Correspondence: marta.jemeljanova@gmail.com

Abstract:

Pollution caused by pharmaceuticals has become an increasingly serious issue, therefore innovative and cost – effective methods of pharmaceutical’s removal must be studied. Clay – humic acid composite materials can be considered as prospective and low cost sorbents for contaminants. The aim of this study is to develop clay mineral and humic acid composite materials and to characterise their possible applications. For this research, three types of clay minerals (montmorillonite, kaolinite and bentonite) were modified with three types of humic substances: technical humic acid from lignite, humic substances extracted from raised bog peat and technical K humate from lignite. The sorption was characterised according to the chosen clay mineral and humic acid type and concentration. The obtained material was characterised by Fourier Transform Infrared spectroscopy and Scanning Electron microscopy. The composite materials were tested for sorption of pharmaceuticals (chloropromazine hydrochloride). The obtained results characterise clay mineral and humic acid composite materials’ possible applications as sorbents for removal of pharmacologically active substances.

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1033–1040 H. Kalkis, Z. Roja, K. Bokse, S. Babris and I. Roja
Work posture load evaluation in medium size metal processing enterprise in Latvia
Abstract |
Full text PDF (538 KB)

Work posture load evaluation in medium size metal processing enterprise in Latvia

H. Kalkis¹², Z. Roja², K. Bokse², S. Babris³ and I. Roja⁴

¹Riga Stradiņš University, Dzirciema street 16, LV-1007 Riga, Latvia
²University of Latvia, Aspazijas blvd. 5, LV-1050 Riga, Latvia
³BA School of Business and Finance, K. Valdemara 161, LV-1013 Riga, Latvia
⁴Riga 1st Hospital, Latvia, Bruninieku 5, LV-1001 Riga, Latvia
*Correspondence: henrijs.kalkis@gmail.com

Abstract:

The aim of this study was to evaluate the exposure of individual workers to ergonomic risk factors associated with upper, lower extremities and trunk WRMSDs and to assess entire body posture for risk of WRMSDs. The company that produces finished metal products (ironing boards) was chosen for the research. Rapid Entire Body Assessment (REBA) was used to assess the entire body posture for risk of WRMSDs. Rapid Upper Limb Assessment (RULA) method was used for ironing boards employees to evaluate exposure of the neck, trunk, arms and legs in relation to physical load. Our study proved that employees are subjected to WRMSDs due to the load on certain body parts during the work: shoulder and neck area, lower back, legs and arms. Forced work postures are an essential risk factor at work. Assemblers and packers are subdued to high risk level, but inspectors – to medium risk level, which corresponds to evaluation with RULA and REBA methods.

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1041–1052 M. Khrapova
Determining the influence of factors on retroreflective properties of traffic signs
Abstract |
Full text PDF (375 KB)

Determining the influence of factors on retroreflective properties of traffic signs

M. Khrapova

Czech University of Life Sciences Prague (CULS), Faculty of Engineering, Department of Vehicles and Ground Transport, Kamýcká 129, CZ165 00 Prague, Czech Republic
Correspondence: khrapova@tf.czu.cz

Abstract:

One of the distinguishing features of future autonomous cars is the ability to take into account and communicate with traffic infrastructure. Thereby detection and recognition of vertical traffic signing is an obvious requirement. Automatic recognition of traffic signs allows to check driver’s reaction time, if it is necessary to react, and in that way to contribute to and increase the road safety. It is especially important in the darkness when the retroreflective sheeting materials on the traffic signs help to increase visibility. Unfortunately, environmental conditions around the traffic signs exert considerable influence on the sign’s surface and alter their retroreflective properties. Many scientists explored different impacts on retroreflective properties of signs. Some impacts attracted more attention (such as detection distances and deterioration with age), some impacts were studied by several scientists only (such as dew and frost) and some factors were even omitted at all (e.g. the temperature during measurements of in-service signs). The paper is focused on the impact analysis of insufficiently explored factors influencing retroreflective properties of traffic sings. The findings of this research can support the development of further experimental research and could become a basis of reliable traffic signs usage on modern and smart roads.

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1053–1061 M. Kiviste, V. Tamme, L. Linnus and R. Halgma
Half-cell potential mapping for corrosion risk evaluation of prestressed concrete ribbed panels from agricultural building after 20 years of service
Abstract |

Half-cell potential mapping for corrosion risk evaluation of prestressed concrete ribbed panels from agricultural building after 20 years of service

M. Kiviste¹*, V. Tamme², L. Linnus¹ and R. Halgma¹

¹Estonian University of Life Sciences, Institute of Forestry and Rural Engineering, Chair of Rural Building and Water Management, F.R. Kreutzwaldi 5, EE51006 Tartu, Estonia
²Estonian University of Life Sciences, Institute of Forestry and Rural Engineering, Chair of Forest Management Planning and Wood Processing Technologies, F.R. Kreutzwaldi 5, EE51006 Tartu, Estonia
*Correspondence: mihkel.kiviste@emu.ee

Abstract:

Corrosion of steel is a significant problem in prestressed concrete structures as it decreases structural capacity and performance. In this research the 20-year-old prestressed concrete ribbed ceiling panels (of type PNS-12) with dimensions of 6 m (length) by 1.5 m (width) from an existing Estonian agricultural building (pigsty) are studied. The objective is to evaluate the corrosion risk of steel reinforcement of ribbed panels by means of a indirect (non-destructive) method and compare the results with a direct method.
The methodology consists of a) non-destructive measurements of half-cell potential and b) comparision with actual condition of steel reinforcement after concrete removal (demolition).
Non-destructive measurements were performed on the 10 longitudinal ribs of 5 ribbed panels, respectively. Steel half-cell potential maps were developed based on 900 measurement points recorded by half-cell (Great Dane).
After destructive tests the ribbed panels including their longitudinal ribs were demolished and the concrete was carefully removed. The position and condition of steel details was photographed (direct method), which enabled the comparison with potential maps (indirect method).
The results demonstrated that in general, half-cell potential maps give a rather good indication on the condition of corroding steel rebars with respect to intact details. Also, half-cell potential maps were found relatively useful in estimating the corrosion risk in the studied precast ribbed panels.

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1062–1070 V. Kolář, M. Tichý, M. Müller, P. Valášek and A. Rudawska
Research on influence of cyclic degradation process on changes of structural adhesive bonds mechanical properties
Abstract |

Research on influence of cyclic degradation process on changes of structural adhesive bonds mechanical properties

V. Kolář¹*, M. Tichý¹, M. Müller¹, P. Valášek¹ and A. Rudawska²

¹Czech University of Life Sciences, Faculty of Engineering, Department of Material Science and Manufacturing Technology, Faculty of Engineering, Kamýcká 129, CZ165 21 Prague, Czech Republic
²Lublin University of Technology, Department of Production Engineering, Mechanical Engineering Faculty, Nadbystrzycka 36, PL20 618 Lublin, Poland
*Correspondence: vkolar@tf.czu.cz

Abstract:

The paper deals with an influence of a cyclic degradation process on changes of a shear tensile strength of single lap-shear adhesive bonds and their elongation according to ČSN EN ISO 9142. Five one-component structural adhesives used in a construction of car body works were used within the research. The degradation of adhesive bonds is a significant factor which influences a quality and a service life of adhesive bonds exposed to environment. A main requirement in production companies is not only reaching satisfactory initial mechanical properties but namely ensuring a reliability and a safety of adhesive bonds during their usage.
These reasons show a great importance of adhesive bonds tests either directly in the operating environment or by a simulation of operating conditions in laboratories. The degradation process of adhesive bonds worsens mechanical properties of not only the bond itself but also of the bonded material. This process is progressing and it is usually permanent and irreversible. It is a change of mechanical and physical properties which can endanger a safety and a reliability of parts, prospectively of the whole equipment. It can leads up to a complete failure of its function in the extreme case. A temperature, a moisture, a direct contact with water and chemicals or an atmospheric corrosion belong among the most serious degradation agents. It is important to take into regard time of the processes influence at the same time which can act either independently or concurrently when their effects grow stronger.
From that reason the adhesive bonds were exposed to the cyclic degradation process according to the standard ČSN EN ISO 9142. Subsequently, the adhesive bonds mechanical properties were tested on universal testing machine and by means of SEM analysis (TESCAN MIRA 3).
Results of mechanical tests proved a fall of the shear tensile strength of single lap-shear adhesive bonds after 42 cycles of the degradation process of 12.8 to 21.7%. The bond strength fall was gradual and it showed a linear trend at some adhesives. Other adhesives showed a significant fall after the exposition to the degradation process after which the strength fall stabilized.

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1071–1079 M. Kotek, M. Krumbholc and V. Hartová
Analysis of operating parameters of hybrid vehicle under real traffic condition
Abstract |

Analysis of operating parameters of hybrid vehicle under real traffic condition

M. Kotek*, M. Krumbholc and V. Hartová

Czech University of Life Science Prague, Faculty of Engineering, Department of Vehicles and Ground Transport, Kamýcká 129, CZ16500 Prague, Czech Republic
*Correspondence: kotekm@oikt.czu.cz

Abstract:

Nowadays, protecting the environment and reducing harmful emissions is an increasingly discussed topic. One way to reduce vehicle emissions, especially for individual car traffic, is to use a hybrid drive. The advantages of the electric drive and the classic combustion engine are used here. By combining both types of drive, a synergetic effect is achieved, where both drives can be used in optimal operating mode.
The aim of the experiment was to demonstrate the benefit of a hybrid vehicle in real driving. The operating parameters of the Lexus LX400h hybrid vehicle was compared to a conventional low-class vehicle Škoda Fábia 1.2 HTP with a classic SI engine. The experiment took place on a route including typical urban, extra-urban and motorway traffic condition. During experiment, the engine operating parameters and CO, CO2, HC and NOX emissions were measured.
The results show that the emission production and fuel consumption of the hybrid vehicle are significantly lower in urban traffic condition than the vehicle with classic internal combustion engine. On the contrary, in motorway conditions, the hybrid vehicle must use both drives, as higher performance is required to overcome higher driving resistances and therefore achieves higher fuel consumption and higher emissions than a conventional vehicle.

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1080–1088 J. Kreicbergs and A. Grislis
Periodic polynomial regression analysis of urban driving characteristics
Abstract |

Periodic polynomial regression analysis of urban driving characteristics

J. Kreicbergs and A. Grislis*

Riga Technical University, Faculty of Mechanical Engineering, Transport and Aeronautics, Department of Automotive Engineering, 1 Kalku Str., LV1658 Riga, Latvia
*Correspondence: juris.kreicbergs@rtu.lv

Abstract:

Urban driving characteristics with a focus on energy consumption have been tested in Riga on three main city streets with inflexible coordinated traffic lights control. The aim of this article is to investigate periodic polynomial regression analysis method to analyse car urban driving parameters’ change during weekday twenty-four hours to assess the influence of vehicle technologies on energy consumption in city driving, to map the energy demand on Riga city main street sections and to evaluate the traffic lights control on flow energetic characteristics. The tests have been done using GPS and OBD data loggers on a test car repetitively driven along a pre-planned route at around-the-clock hours. A regression analysis using periodic polynomials was developed and applied to evaluate the traffic flow characteristics with a given time shift. It was concluded that using polynomial regression function, the polynomial order has to be at least seven although a visual conformation of good regression line to the measured data has to be checked especially with lower orders. To evaluate the traffic conditions at a given 20 minutes to one hour shift the application of regression function is limited for the periods with fast changing traffic flow, especially after the end of rush hours when the usability of regression line for the given data has to be checked individually for tested street sections.

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1089–1096 M. Krumbholc and M. Kotek
Analysis of operation parameters of electric and gasoline vehicle in real driving
Abstract |

Analysis of operation parameters of electric and gasoline vehicle in real driving

M. Krumbholc* and M. Kotek

Czech University of Life Science Prague, Faculty of Engineering, Department of Vehicles and Ground Transport, Kamýcká 129, CZ16500 Prague, Czech Republic
*Correspondence: krumbholc@tf.czu.cz

Abstract:

The reduction of transport-generated energy consumption and consequent emission production are currently a problem of global interest. Electric vehicles (EVs) are considered as one promising technological solution for limiting transport-generated energy consumption and emission production, but theirs operating parameters are strongly influenced by immediately operating conditions and it is often very problematic to prove or disprove benefits of EVs in real operation.
The aim of this paper is to present comparison of operating parameters of the full-electric vehicle VW e-UP! with identical vehicle Skoda Citigo with gasoline engine in real driving. Both vehicles were tested together in several different areas of the Czech Republic. The experiment was focused on analysis of energy (fuel) consumption and production of exhaust gases (CO, CO2, NOX). VAG-COM diagnostics system was used for sensing engine operating parameters, GPS coordinate were measured by Garmin GPS-18x, vehicle Skoda Citigo was equipped by the PEMS analyzer VMK for RDE emission sensing (CO, CO2, HC, NOX). The results bring a real comparison between the electric vehicle and the vehicle with gasoline engine in terms of fuel consumption and emissions production.

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1097–1106 K. Leiten, P. Kirotar and M. Kiviste
Hygrothermal analysis of masonry wall with wool glass interior insulation
Abstract |

Hygrothermal analysis of masonry wall with wool glass interior insulation

K. Leiten*, P. Kirotar and M. Kiviste

Estonian University of Life and Science, Institute of Forestry and Rural Engineering, Kreutzwaldi 5, EE51014 Tartu Estonia
*Correspondence: kadri.keskkyla@mail.ee

Abstract:

When the external appearance of the building is fixed due to heritage requirements the interior thermal insulation is the only possible solution for thermal upgrade of the building envelope. Applying internal insulation to existing buildings is known to pose a challenge in relation to hygrothermal risks, as this can lead to high relative humidity levels, condensation and ultimately, mould growth and decay. The case study building is under historical preservation and therefore this is not allowed to be insulated from outside. The paper describes the hygrothermal assessment of applying internal glass wool insulation and vapour barrier in masonry wall with air gap. In addition to the calculations the condition investigation was also performed. Data loggers measuring temperature and RH were applied during the period of 31.01.2013–16.02.2013. The conclusions were based to theoretical calculations (case study and DIN 4108-3) and practical measurement results based on the data logger values obtained. The calculations showed that glass wool and vapour barrier insulated system were in risk on condensation but the condensed water dries out during summer time. Due to the fact that logger measurements were recorded during the time when inside plastering was still in progress the relative humidity in the room was very high. As a result of calculations it is possible to build this type of wall effectively, but in this case it was not the most reliable way because of ongoing interior fitting.

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1107–1122 R. Majdan, R. Abrahám, D. Uhrinová and J. Nosian
Contamination of transmission and hydraulic oils in agricultural tractors and proposal of by-pass filtration system
Abstract |

Contamination of transmission and hydraulic oils in agricultural tractors and proposal of by-pass filtration system

R. Majdan*, R. Abrahám, D. Uhrinová and J. Nosian

Slovak University of Agriculture in Nitra, Faculty of Engineering, Department of transport and handling, Tr. A. Hlinku 2, SK949 76 Nitra, Slovak Republic
*Correspondence: radoslav.majdan@gmail.com

Abstract:

Tractors use various types of lubricating oils in transmission and hydraulic system. Oils are contaminated by different ways depending on the work of the lubricated system. There are general requirements on the cleanliness level of the oil in the tractor transmission and hydraulic system according to the standard DIN 51524. According to all that, this paper presents research conducted by two tractors. The tractor John Deere 8100 used only its own implements (ploughs, trailers etc.) and it was operated in compliance with user manual. In this tractor, the oil cleanliness level met the standard DIN 51524 because reached the stage 7 (NAS 1638). The tractor Zetor Forterra 124 41 contained extremely contaminated oil, it reached stage > 12 (NAS 1638), due to the non-standard operation which was opposite to the user manual. Both ways of tractor operation are typical for farmers activity in the Slovak Republic, depending on the tractor type and style of agricultural production at most. The second part of this paper is aimed at the proposal of by-pass filtration system to eliminate the oil contamination. The by-pass filtration system is the second stage of the oil filtration in the tractor, whereas the first one means standard tractor filter. Function of the system was tested according to the decrease of chemical elements concentration characterising the oil contamination and visual method based on filter and its change after operating of tested tractor. There was evaluated the decrease of concentration of Fe (41.6%), Cu (28.7%) and Si (20.5%) after by-pass filtration system was running under operational conditions. It can be concluded that the by-pass filtration system was proposed correctly and it is suitable for tractors operation.

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1123–1131 D. Maksimov, H. Kalkis, Y. Perevoschikov and Z. Roja
Use of qualimetry method in production labour estimation
Abstract |
Full text PDF (819 KB)

Use of qualimetry method in production labour estimation

D. Maksimov¹*, H. Kalkis², Y. Perevoschikov¹ and Z. Roja³

¹Institute of Economics and Management, Udmurt State University, 1, Universitetskaya Str, bld. 4, RU426034 Izhevsk, Russia
²Faculty of European Studies, Riga Stradins University, Dzirciema street 16, LV 1007 Riga, Latvia
³University of Latvia, Raina blvd. 19, LV-1586 Riga, Latvia
*Correspondence: maksim.dan.gen@gmail.com

Abstract:

Every work process of production organization involves employees and employer interaction with each other by “agreement”. Such agreement is contracted based on the implementation of concrete types of work processes in particular workplaces. The general the total number of workplaces are continuous interaction areas of people to transform substance, energy and information. The solution of the assigned tasks requires the methodology for designing product quality, analyzing market consumer needs, forecasting potential prices and detecting effectiveness in order to present the strategic objectives in digital values. This study is part of a larger investigation which involves principles of economic metrology and qualimetry of work. The purpose of the research is to demonstrate use of qualimetry in the production organization, based on experience of several years in many industry organisations by focusing on engineering.

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1132–1137 Č. Mizera, D. Herák, P. Hrabě and T. Saller
Linear pressing of coconut copra meal (Cocos nucifera L.) under different temperatures
Abstract |

Linear pressing of coconut copra meal (Cocos nucifera L.) under different temperatures

Č. Mizera¹*, D. Herák¹, P. Hrabě² and T. Saller¹

¹Czech University of Life Sciences Prague, Faculty of Engineering, Department of Mechanical Engineering, Kamýcká 129, CZ165 21 Praha 6 Suchdol, Czech Republic
²Czech University of Life Sciences Prague, Faculty of Engineering, Department of Material Science and Manufacturing Technology, Kamýcká 129, CZ165 21 Praha 6 Suchdol, Czech Republic
*Correspondence: mizera@tf.czu.cz

Abstract:

Pressing of vegetable oils plays an important role in the food processing. This study described the compression behaviour of copra (Cocos nucifera L.) using the universal compression testing machine and vessel diameter of 60 mm with a plunger. The influence of heat treatment on oil recovery efficiency and specific mechanical energy were determined. Compression tests at the rate of 1 mm s−1 under five different temperatures 20, 40, 60, 80 and 100 °C were performed. The measuring range of force was between 0 kN and 50 kN. It has been found that the amount of obtained oil increased and specific mechanical energy decreased with increased temperature. Measured data were analysed by computer software Mathcad 14 (MathCAD 14, PTC Software, Needham, MA, USA). Mathematical model describing the mechanical behaviour of bulk copra under compression loading was represented.

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1138–1145 V. Mitrofanovs, I. Boiko and Ē. Geriņš
Management of parts and components for units and assemblies in mechanical engineering industry and its impact on the environment
Abstract |

Management of parts and components for units and assemblies in mechanical engineering industry and its impact on the environment

V. Mitrofanovs*, I. Boiko and Ē. Geriņš

Riga Technical University, Institute of Mechanical Engineering, Viskalu 36A, LV-1006 Riga, Latvia
*Correspondence: v.mitrofanovs@meistars.lv

Abstract:

Most of the service centers operating in the repair and maintenance of machines and mechanisms apply warehouse management systems based on event prediction, which ensures inventory replenishment based on the initial diagnosis of the units. Such methodology is enforced measure, since the components and assemblies, even from the same manufacturer, having similar functions, design and connecting components have their own engineering numbers and part numbers for ordering. Unfortunately, this method is relevant only with perfect logistics and minimal time factor. If these criteria cannot be fulfilled, the maintenance and repair time increases, especially at a distance from logistic centers.
By reducing lost sales and quick customer satisfaction, own warehouse stocks based on statistical data increases. Unfortunately, none of the modern methods gives a 100% result and eventually leads to overstocking and formation of deadstock. On the other hands more and more components are made from composite materials, complex alloys, permanent joints are being used. But due to ineffective management the significant part of expensive components is became needless. The aim of this research is to develop an algorithm allowing to optimise the logistics chain and reduce the inventory and deadstock, reduce disposal of used and obsolete units and assemblies, resulting in significantly lower consumption of natural resources, energy and reduced negative impact of waste on the environment. Our research shows that in various fields of science there are being developed methodologies, which would solve the described tasks by combining those methodologies in a single algorithm.

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1146–1154 J. Olt, V. Maksarov and A. Efimov
Improving the quality of critical tractor parts through the dynamic stabilisation of the manufacturing process in regard to CNC machines
Abstract |

Improving the quality of critical tractor parts through the dynamic stabilisation of the manufacturing process in regard to CNC machines

J. Olt¹*, V. Maksarov² and A. Efimov²

¹Estonian University of Life Sciences, Chair of Biosystems Engineering, Kreutzwaldi 56, EE51006 Tartu, Estonia
²Saint-Petersburg Mining University, Department of Mechanical Engineering, 2, 21st Line, St Petersburg RU199106, Russia
*Correspondence: jyri.olt@emu.ee

Abstract:

This article focuses on the evaluation of a rod improvement which is considered in detail below. The rod in question is part of an hydraulic cylinder manufacturing process which takes place on CNC machines. The need for ensuring a process improvement in this area arose because the rod often breaks down under operational conditions. It was found that the cause of this is a finishing operation in the existing production process. The effect of charging which occurred during the grinding process brings about the embedding of abrasive particles into the workpiece surface layer. Therefore, at the running-in stage, the mating surfaces on the rod and the system being used to seal the rings both experience intense wear in their contact areas, with this being caused by abrasive microparticles which serves to reduce the performance characteristics of the part in question. However, even if we dispense with the grinding process, ensuring the necessary roughness of Ra = 0.63 μm at the machining stage alone will present problems of their own for a number of reasons. First and foremost is the connection with the phenomenon that results in an auto-oscillation processes which is generated by the manufacturing system, as well as the formation of flow chips during machining on CNC machines. In this regard, in order to avoid any negative factors creeping into the process, we propose that a new approach be taken in achieving the necessary surface roughness, one which is based on the suppression of the auto-oscillation process during machining by means of creating a selective metastable structure. At the machining stage, any inhomogeneous structure in the local chip formation area will be destroyed, thereby suppressing the auto-oscillation process and reducing the surface roughness. Eventually, the proposed method will allows the grinding operation to be dispensed with entirely from the manufacturing process.

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1155–1164 V. Osadčuks, A. Pecka and A. Galiņš
Usage of grid support inverter on long distribution grid lines
Abstract |

Usage of grid support inverter on long distribution grid lines

V. Osadčuks*, A. Pecka and A. Galiņš

Latvia University of Life Sciences and Technologies, Faculty of Engineering, Institute of Energetics, Čakstes blvd. 5, LV-3001 Jelgava, Latvia
*Correspondence: vtl@tvnet.lv

Abstract:

The paper focuses on the evaluation of new possibilities to improve voltage quality in remote branches of 230 V grid. Decrease of power electronic costs may potentially make battery-backed inverters a viable alternative to the costly reconstruction of 230 V distribution grid connections, which are of poor quality or cannot match changing load requirements, extending power transmission lines or adding boost transformers. The object of the current study is a household-type consumer with 20 A single-phase connection to distribution line with a distance of 2 km to a 20 kV transformer station. The calculated resistance of the power line is 2.8 ohms. The load profile was captured during 5 days in summer and 10 days in winter and was used to calculate the capacity of the grid support equipment. Measurements indicated, that in the worst case 2% of time the voltage was below 10% of nominal and 8% of time – below 5% of it. This is outside of the regulatory limits of EU and national regulations. The experimental setup for a voltage quality improvement system was based on an OutBack Power Radian series grid inverter with 7 kW output power. Battery consisting of 12 V 120 Ah VRLA accumulators wired in 48 V system was used. The inverter was configured to work in grid support mode using battery power when the consumer’s active load increased above 1.2 kW. Results showed improvement in voltage quality over the full consumer load range. The total efficiency of the grid support system was 89%. The use of DC bus and batteries allows easy incorporation of renewable energy sources, thus giving the opportunity to scale power and battery capacity of the system. An Additional benefit of using a battery-backed inverter in grid support mode is that consumer can temporarily use more power that is allowed by grid due to its capacity constraints.

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1165–1180 T. Ovaska, S. Niemi, K. Sirviö and O. Nilsson
Exhaust particle number of a non-road diesel engine fuelled by methyl esters with different fatty acid compositions
Abstract |

Exhaust particle number of a non-road diesel engine fuelled by methyl esters with different fatty acid compositions

T. Ovaska*, S. Niemi, K. Sirviö and O. Nilsson

University of Vaasa, School of Technology and Innovations, P.O. Box 700, FI-65101 Vaasa, Finland
*Correspondence: teemu.ovaska@univaasa.fi

Abstract:

The main aim of this study was to find out how methyl esters with different fatty acid compositions affect the exhaust particle numbers. Along with fossil diesel fuel oil (DFO) and renewable diesel (HVO), a high-speed non-road diesel engine was fuelled by rapeseed (RME) and soybean (SME) methyl esters. Particle numbers within the size range of 5.6–560 nm were measured by means of an engine exhaust particle sizer (EEPS). The exhaust smoke, gaseous emissions and the basic engine performance were also determined. During the measurements, the 4-cylinder, turbocharged, intercooled engine was run according to the non-road steady cycle. Methyl esters reduced particles within the size range of 70 to 200 nm. For RME and SME, both positive and significant correlations were found between the sum of the particle numbers detected above the size category of 23 nm and methyl palmitate (C16:0), methyl stearate (C18:0) and methyl linoleate (C18:2) contents at 10% load at rated speed. In terms of nitrogen oxide (NOx) and hydrocarbon (HC) emissions, HVO was beneficial while carbon monoxide (CO) emission was the lowest with DFO. The level in smoke emission was negligible.

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1181–1190 V. Papez and S. Papezova
Effective control and battery charging system of an island PV power plant
Abstract |

Effective control and battery charging system of an island PV power plant

V. Papez¹ and S. Papezova²*

¹Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Electrotechnology, Technicka 2, CZ166 27 Pague 6, Czech Republic
²Czech University of Life Sciences in Prague, Faculty of Engineering, Department of Electrical Engineering and Automation, Kamycka 129, CZ165 21 Prague 6 ˗ Suchdol, Czech Republic
*Correspondence: papezovas@tf.czu.cz

Abstract:

The paper presents a new concept of an autonomous PV power plant regulatory system with LiFePO4 batteries, which was functionally verified. The hardware system is significantly simpler and more operationally reliable. It also shows higher efficiency and lower acquisition costs than conventional commercial systems. The proposed control system was optimized for charging a multi-cell battery by PV electric energy. The system automatically maximizes the power supplied by the photovoltaic source and minimizes the power loss caused by balancing the individual cell charging processes. The problem of charge balancing is solved without the balancers. Battery cells are recharged from the separate converters supplying the PV power. The converters are controlled to observe a LiFePO4 battery charging mode while controlling the photovoltaic generator (PVG) load resistance based on an MPP monitoring. PVG power is not supplied to the charged cells, which are in this way protected from overcharging. The entire PVG power is fed to the cells to be charged. The transmission from the converters is controlled in order not to exceed the voltage and current limits at the terminals and to minimize the actual voltage deviation from the control voltage at the PVG output. The control voltage is generated as an MPP voltage approximation according to the load characteristics and the actual PVG operating conditions.

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1191–1198 T. Schnabel, H. Huber, A. Petutschnigg and A. Jäger
Analysis of plant materials pre-treated by steam explosion technology for their usability as insulating materials
Abstract |

Analysis of plant materials pre-treated by steam explosion technology for their usability as insulating materials

T. Schnabel¹*, H. Huber¹, A. Petutschnigg¹² and A. Jäger³

¹Salzburg University of Applied Sciences. Department of Forest Products Technology & Timber Constructions. Marktstraße 136a, AT5431 Kuchl, Austria
²BOKU University of Natural Resources and Life Sciences, Konrad Lorenz-Straße 24, AT3430 Tulln, Austria
³University of Applied Sciences Upper Austria, Faculty of Engineering, Department of Bio & Environmental Technology, Stelzhamerstr. 23, AT4600 Wels, Austria
*Correspondence: thomas.schnabel@fh-salzburg.ac.at

Abstract:

Raw materials of annual plants fibres are not easily usable for industrial production applications. Pre-treatment of the annual plant fibres is necessary to increase the homogeneity of the material and to improve the material properties. This study deals with the influence of steam explosion treatment on the quality of annual plant fibres used as insulating material.
Maize and wheat straw were selected for production of insulating panels. To clarify the changes within the structure of the plants due to the pre-treatment process material analysis was carried out using FT-IR spectroscopy and raster electron microscope. Furthermore, the bulk density and the thermal conductivity were analysed as important values for insulating materials.
The results showed that the pre-treatment process homogenizes the materials and the processes could be used for the production of bulk insulation.

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1199–1206 K.K. Singh, A. Meshram, D. Gautam and A. Jain
Hydrogen production using waste aluminium dross: from industrial waste to next-generation fuel
Abstract |
Full text PDF (992 KB)

Hydrogen production using waste aluminium dross: from industrial waste to next-generation fuel

K.K. Singh*, A. Meshram, D. Gautam and A. Jain

Indian Institute of Technology, Banaras Hindu University, Department of Metallurgical Engineering, IN221005 Varanasi India
*Correspondence: kksingh.met@iitbhu.ac.in

Abstract:

This article describes the production of hydrogen from white aluminium dross, an industrial waste generated in the aluminium smelter plants. Hydrogen is generated by metal-water reaction between aluminium and water in presence of alkalis like sodium hydroxide and potassium hydroxide. Aluminium dross is described as a heterogeneous material with its major constituents being metallic aluminium, alumina and other salt fluxes like NaCl and KCl. Utilizing the metallic aluminium content entrapped in the matrix of alumina for the metal-water reaction has been the driving force for the waste recycling and simultaneous hydrogen production. Bulk aluminium dross was crushed and downsized. The finer fraction of the powdered aluminium dross is used for the experiments. The effects of dross in the alkaline solution, temperature of the solution and the time of the reaction were studied to understand the generation of hydrogen. The alkaline solution breaks the protective layer of alumina and exposes the entrapped aluminium content to water, thereby commencing the hydrogen liberation.

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1207–1215 K. Sirviö, S. Niemi, R. Help, S. Heikkilä and E. Hiltunen
Behavior of B20 fuels in arctic conditions
Abstract |

Behavior of B20 fuels in arctic conditions

K. Sirviö*, S. Niemi, R. Help, S. Heikkilä and E. Hiltunen

University of Vaasa, School of Technology and Innovations, PL 700, FIN-65101 Vaasa, Finland
*Correspondence: katriina.sirvio@univaasa.fi

Abstract:

Several renewable and sustainable liquid fuel alternatives are needed for different compression-ignition (CI) engine applications to reduce greenhouse gas (GHG) emissions and to ensure proper primary energy sources for the engines. One of the shortcomings of several bio oils and first generation biodiesels has been their cold properties. Still, the need for alternative fuels is also present in arctic areas where the storing of the fuels may become problematic. The main aim of the current study was to determine how the storage related properties of fuel blends change if the fuels first freeze and then melt again. The samples were analyzed three times: as fresh, and after the first and second freezing-melting phase transitions.
The share of renewables within the blends was 20 vol-%. Rapeseed methyl ester (RME) and animal-fat based methyl ester (AFME) were blended with LFO in a ratio of 80 vol-% of LFO and 20-vol% of RME or AFME.
The investigated and compared properties were the FAME content of the neat FAMEs, and kinematic viscosity, density, oxidation stability index, and acid number of the blends. Cold filter plugging point was measured for AFME and its blend. According to the results, the quality of the FAMEs and their blends did not change significantly during the freezing over. The freezing-melting phase transition seems, thus, not to be as big a threat to the fuel quality as the high temperatures are. According to the results of this study, the studied fuels were feasible after the freezing-melting phase transition.

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1216–1226 K. Tihomirova, V. Denisova, K. Golovko, O. Kirilina–Gutmane, L. Mezule and T. Juhna
Management of wastewater from landfill of inorganic fiberglass
Abstract |
Full text PDF (823 KB)

Management of wastewater from landfill of inorganic fiberglass

K. Tihomirova¹²*, V. Denisova¹, K. Golovko¹, O. Kirilina–Gutmane², L. Mezule¹ and T. Juhna¹

¹Riga Technical University, Faculty of Civil Engineering, Research Centre for Civil Engineering, Water Research Laboratory, Kipsalas 6a–263, LV–1048 Riga, Latvia
²The Institute of Food Safety, Animal Health and Environment ‘BIOR’ Elemental analysis division, Lejupes street 3, LV–1076 Riga, Latvia
*Correspondence: kristina.tihomirova@rtu.lv

Abstract:

Sustainability is one of the key factors in smart environment management and include the reduction of environment footprint. The waste and wastewater management plans are aimed on actions to reduce the amount of waste and environmental pollution. This includes collection of waste, logistics, storage, processing or valorisation and also treatment. The aim of this research was to evaluate environmental pollution risk and to demonstrate one of the wastewater management schemes to reduce the pollution level.
Evaluation of the better management scheme was performed in one of the landfills in Latvia, where fiberglass waste and other inorganic waste is stored. Onsite evaluation results demonstrated the need to develop a better wastewater management scheme of inorganic fiberglass landfill. After that, laboratory–scale experiments for conventional coagulation and biodegradation tests have been performed for efficient management.

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1227–1234 I. Tipans, J. Viba, M. Irbe and S.K. Vutukuru
Analysis of non-stationary flow interaction with simple form objects
Abstract |

Analysis of non-stationary flow interaction with simple form objects

I. Tipans, J. Viba, M. Irbe and S.K. Vutukuru*

Riga Technical University, Faculty of Mechanical Engineering, Transport and Aeronautics, Department of Theoretical Mechanics and Strength of Materials, Viskalu Street 36A, LV – 1006, Riga, Latvia
*Correspondence: vshravankoundinya1989@gmail.com

Abstract:

The paper is devoted to the analysis of a non-stationary rigid body interaction in a fluid flow. Initially, an approximate method for determining the forces due to fluid interaction with the rigid body is offered. For this purpose, the plane movement of a mechanical system with an infinite DOF (degrees of freedom) is reduced to 5 DOF motion: 3 DOF for the body and 2 DOF for the areas of compression and vacuum in fluid flow. Differential equations of non-stationary motion are formed by the laws of classical mechanics. The use of an approximate method has been quantified by computer modelling. The average difference in results was found to be small (< 5%). The analysis of the fluid (air) interaction is carried out for a rigid body of two simple geometries – flat plate and diamond. The results obtained are used to refine the parameters of the proposed approximate method that is addressed in the present study for fluid interaction with the non-stationary rigid body. Theoretical results obtained in the final section are used in the analysis of the movement of prismatic bodies in order to obtain energy from the fluid flow.

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1235–1245 M. Topol, P. Kic and P. Neuberger
Reduction of moisture and thermal conductivity of wet walls by special plaster
Abstract |

Reduction of moisture and thermal conductivity of wet walls by special plaster

M. Topol¹*, P. Kic¹ and P. Neuberger²

¹Czech University of Life Sciences Prague, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 21 Prague, Czech Republic
²Czech University of Life Sciences Prague, Faculty of Engineering, Department of Mechanical Engineering, Kamýcká 129, CZ165 21 Prague, Czech Republic
*Correspondence: TopolMilan@seznam.cz

Abstract:

This paper is focused on the problems of moisture reduction in old buildings. Wet walls are very common problem of old buildings, but it can appears also in new buildings as well. The moisture in the wall influence the insulation quality; bigger heat losses continuously cause problems of worse heat balance, higher consumption of energy for heating and it can result in not sufficient indoor conditions in such a room or building. Old rural residential buildings and also agricultural buildings for housing of animals, storage of different materials, workshops etc. could be repaired and reconstructed by the used of some special methods. The application of special plaster can reduce the walls moisture as well as improve the thermal properties of the buildings by reduction of thermal conductivity. This paper includes the results of laboratory experiments focused on research of plaster properties (temperature, moisture and thermal conductivity) and tests provided in the real building. Different measuring principles, enabling mutual comparison of results were used for this research. The measurement results showed a significant effect of high wall moisture on the heat losses. Differences between the walls improved by new tested plaster and old untreated walls are discussed in this paper. Obtained results from this measurements and findings may be useful for further research in this issue as well as for the practical solutions for similar problems in many old buildings.

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1246–1254 Z. Vondrášek, V. Ryženko, M. Linda
Thermal analysis of asynchronous machines under intermittent loading
Abstract |

Thermal analysis of asynchronous machines under intermittent loading

Z. Vondrášek, V. Ryženko*, M. Linda

Czech University of Life Sciences Prague, Faculty of Engineering, Kamýcká 129, CZ165 21 Prague, Czech Republic
*Correspondence: ryzhenko@tf.czu.cz

Abstract:

The operation of electric machines is accompanied by losses which are mostly converted to heat. The heat needs to be dissipated from the machine. With a properly dimensioned motor, the arising heat is balanced with dissipated one. After the motor is started at ambient temperature, all functional parts of the machine are gradually warmed until stabilized. Any overloading of the machine leads to stabilization at temperatures higher than expected by the designers. High temperatures in the machine could cause a crash by damaging an insulation. In case of machines with permanent magnets, the temperature affects their magnetic properties and can leads to demagnetization at the Curie temperature. Therefore, the measuring of temperature is so important for verifying the allowed warming of the motor. Contact and noncontact methods could be used for temperature measuring. Thermal warming and temperature distribution in an electric machine can be also determined by theoretical calculations based, for example, on the finite element method. This method is used by a number of computer software such as Ansys. The article deals with generation and propagation of heat in electric motors and with measuring of warming characteristics with a variable value of a load factor for intermittent periodic loading of asynchronous machine. The loading is carried out by the dynamometer. The temperature measurement is implemented by temperature sensors which are located on the stator winding of the asynchronous motor and are in operation for the whole time the motor is loaded.

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