Volume 8 (2010)
  Special Issue I

International Scientific Conference
Biosystems Engineering 2010

13.-24. May 2010, Tartu, Estonia

Conference and volume information – PDF (198 K)

Contents


Pages

5-11 A. Aboltins, J. Palabinskis and G. Ruškis
The Investigations of Heating Process in Solar Air Heating Collector
Abstract |
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The Investigations of Heating Process in Solar Air Heating Collector

A. Aboltins¹, J. Palabinskis¹ and G. Ruškis²

¹Institute of Agricultural Machinery, Latvia University of Agriculture,
Cakstes 5, LV3001, Jelgava, Latvia; e-mail: aivars.Aboltins@inbox.lv
²Institute of Agricultural Machinery, Latvia University of Agriculture,
Cakstes 5, LV3001, Jelgava, Latvia; e-mail: Janis.Palabinskis@llu.lv

Abstract:

The aim of the research is to find the optimal technical solutions, utilized materials as absorbers, operation parameters and power possibilities for a solar collector. Different absorbers of sun radiation, the absorbers’ ability and efficiency in air heating solar collector are compared. 0.1 x 0.5 x 1.0 meters long equipment for experimental research into the materials of solar air heating collector was built. The experimental data were measured and recorded in the electronic equipment REG. The investigations are devoted to the sun following collectors, which guarantee perpendicular location for all experimental time of the plane of absorber to the flow of the sun radiation. The collector covered material was a polystyrol plate and absorbers were: a) black colored steel tinplate and b) slices of black colored beer cans. The use experimental data received expressions of heating degree of air in collector depending on sun radiation and distance from absorber (steel tinplate) at 35 cm and 60 cm from inlet. In favorable weather conditions the heating degree of the ambient air with absorber black colored slices of beer cans reaches more than T = 10o C at the air velocity 0.9 m s-1.

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12-24 A. Andrijanovitš, M. Egorov, M. Lehtla and D. Vinnikov
New Method for Stabilization of Wind Power Generation Using Energy Storage Technology
Abstract |
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New Method for Stabilization of Wind Power Generation Using Energy Storage Technology

A. Andrijanovitš, M. Egorov, M. Lehtla and D. Vinnikov

Department of Electrical Drives and Power Electronics,
Tallinn University of Technology, Ehitajate tee 5, EE19086 Tallinn, Estonia;
e-mail: sergejeva84@hot.ee; mikhail.egorov@ttu.ee; mlehtla@cc.ttu.ee; dm.vin@mail.ee

Abstract:

Wind power appears to be one of the most perspective and widespread renewable energy sources in Estonia. However, wind is difficult to forecast. This complicates production planning and parallel operation with compensating power plants, allowing periods of excess energy and lack of energy to occur. This paper proposes a new energy storage technology to compensate unstable operation of windmills. This is based on a hydrogen buffer, which accumulates excess energy from windmills and transfers it to the DC-link of windmills converter. As all components of the hydrogen buffer are electrically connected to the DC-link, there are three main stages. The first stage is hydrogen production, which is realized with the help of water electrolysis in periods of excess energy. Interfacing is carried out with electrical components, such as DC/DC converter with a step-down isolation transformer. The second stage is hydrogen storage and delivery. The produced hydrogen is accumulated in a tank locally or in industrial gas storage. Hydrogen may be mixed with natural gas and distributed to natural gas pipelines. The third stage is electricity production. The stored energy is used to produce electrical energy during the absence of wind or in conditions of a weak wind. Hydrogen is converted into electricity by a fuel cell. Interfacing is carried out using electrical components with the help of DC/DC converter with a step-up isolation transformer. The paper represents the structure of the proposed hydrogen-based energy buffer and reviews its main elements.

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25-32 A. Annuk, H. Tammoja, H. Agabus, K. Toom and T. Tamm
Possibilities for Correcting Forecast Errors by Cutting off Production Chart Peaks
Abstract |
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Possibilities for Correcting Forecast Errors by Cutting off Production Chart Peaks

A. Annuk¹, H. Tammoja², H. Agabus³, K. Toom¹ and T. Tamm¹

¹ Department of Energy Application, Institute of Technology,
Estonian University of Life Sciences, 56 Kreutzwaldi Str., EE51014 Tartu, Estonia
e-mail: andres.annuk@emu.ee
² Department of Electrical Power Engineering, Tallinn University of Technology,
Ehitajate Rd. 5, EE19086 Tallinn, Estonia; e-mail: heiki.tammoja@ttu.ee
³ Nelja Energia LLC, 1 Regati pst., EE11911 Tallinn; e-mail: hannes@4energia.ee

Abstract:

In this paper we describe a conception for the mitigation of wind power fluctuations by cutting off production chart peaks.
The rapid growth of wind energetics has been induced by several factors. Although the government support may be the main incentive, other important motives include the increasing network access fees and strict requirements set for ensuring the balancing capacity of production.
However, such capacity has the tendency of being underdeveloped. The possibilities of the operating oil-shale plants for providing the capacity to balance the wind parks are running out. Sudden changes in the oil-shale plant output contribute to additional CO2 emissions, increased fuel consumption and decreased boiler efficiency. Under the circumstances, the transmission system operator (TSO) can face the need to reduce the power output of the wind parks. The operators of the wind parks integrated into the transmission network are responsible for presenting to TSO a 24 h forecast of their output power.
The forecast error is mainly specified in terms of Mean Absolute Percentage Error (MAPE), which for Estonian wind parks is about 20% on average. For forecast error estimation we have also applied the notion of Mean Percentage Error (MPE). Estimation of Pakri wind park data shows divergent actual forecast errors for different values of output power. For the values approximating the rated power of the wind park, the actual output power is larger than predicted. This situation clearly arises when the proportional output power is over 80% and MAPE is quite evenly distributed around 19.2%. In good wind conditions, for the relative output power value of 80%, the share of energy lost by cutting off production chart peaks amounts to 8.6% of the total energy production. The share is rapidly decreasing with declining wind conditions. Nevertheless, the average share of energy lost does not exceed 5%. The cut off energy might be applicable for heat production in boiler houses, although it is cheaper than the energy supplied to the electrical network.

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33-38 V. Dubrovin and M. Melnychuk
Cleaner Production of Biomass and Biofuels
Abstract |
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Cleaner Production of Biomass and Biofuels

V. Dubrovin and M. Melnychuk

National University of Life and Environmental Sciences of Ukraine
15 Geroiv Oborony Str., 03041 Kiev, Ukraine
e-mail: dubrovin@nauu.kiev.ua; maksym@nauu.kiev.ua

Abstract:

Ukrainian agriculture is an industry which produces a huge quantity of biomass. The main part of the biomass potential is made up by straw. By moderate estimations only 20% of the total amount of straw can be used for energy production. All plant growing and biomass processing technologies can be based on cleaner production methodology. Only a few ecological options in corn growing technology gave real profit, which was ca 220 UAH per hectare. The main steps for rearing Trichogramma insects are technical services in laboratory conditions and soft implementation of them on agricultural plants by special aircraft. The most important result of the research is an overview of the possibilities of Ukraine to cover up to 12% of the total primary biomass energy demand for cleaner biofuel production.

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39-46 I. Dukulis, G. Birzietis, V. Pirs, A. Birkavs and Z. Jesko
Exhaust Emissions from Vehicles Operating on Rapeseed Oil Fuel
Abstract |
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Exhaust Emissions from Vehicles Operating on Rapeseed Oil Fuel

I. Dukulis, G. Birzietis, V. Pirs, A. Birkavs and Z. Jesko

Motor Vehicle Institute, Faculty of Engineering, Latvia University of Agriculture,
5 J. Cakstes boulv., Jelgava, LV-3001, Latvia; e-mail: ilmars.dukulis@llu.lv;
gints.birzietis@llu.lv; vilnis.pirs@llu.lv; aivars.birkavs@llu.lv; zanis.jesko@llu.lv

Abstract:

One of the primary incentives for expanding the production and use of biofuels worldwide is the potential environmental benefit that can be obtained from replacing petroleum fuels with fuels derived from renewable biomass resources. The use of straight vegetable oil (SVO) in diesel engines is one of the available alternatives, but its use in existing vehicles usually requires modification of engine or fuel system components. In order to find out the trends in changes of different exhaust emission components using fossil diesel and pure rapeseed oil fuel, the car VW GOLF and the truck MAN 19,464 were modified using one-tank and two-tank conversion kits respectively. To ensure stable driving characteristics, a Mustang Chassis Dynamometer MD-1750 was used and for the determination of the content of different exhaust gas components, the AVL SESAM multicomponent exhaust gas measurement system was used. The analyses of obtained results show that the content of NOx and SO2 using rapeseed oil fuel in comparison with fossil diesel decreased with both one-tank and two-tank systems. The content of CO and mechanical particles was higher using rapeseed fuel, but the content of unburned hydrocarbons differs depending on the used engine modification system. Since in the one-tank system original engine nozzles were replaced, the pilot studies of the influence of ignition timing on vehicle power characteristics and exhaust emissions were carried out. It was found out that changing the ignition timing from 10.5 to 18.5 degrees decreases the content of CO, mechanical particles and unburned hydrocarbons by up to 70% without losses in power and torque.

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47-59 I. Ehrhardt, H. Seidel and N. Doden
Potentials for Savings by Implementing RFID and Telematic Technologies in the Timber and Biomass Supply Chain
Abstract |
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Potentials for Savings by Implementing RFID and Telematic Technologies in the Timber and Biomass Supply Chain

I. Ehrhardt, H. Seidel and N. Doden

Fraunhofer Institute for Factory Operation and Automation IFF,
Sandtorstrasse 22, DE39106 Magdeburg, Germany
e-mail: Ina.Ehrhardt@iff.fraunhofer.de; Holger Seidel@iff.fraunhofer.de;
Nadine.Doden@iff.fraunhofer.de

Abstract:

While RFID and telematic technologies already enjoy wide implementation among retailers and logistics providers, their use in timber and biomass logistics is still in a phase of initial testing and pilot projects. Implementable technologies provide cross-organizational functionalities and facilitate the optimization of the supply chain ‘from the forest to the factory’. Naturally, timber and biomass supply processes confront logistics with special challenges. Moreover, there are constraints and a need for further developments. Nonetheless, these technologies have been effectively and successfully implemented in a number of projects. The standardization of information technology will be a fundamental prerequisite for the acceptance of RFID and telematic technologies.

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60-67 M. Hautala
Measurement and Modelling of Circumstances in Animal Houses: What, Why and How
Abstract |
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Measurement and Modelling of Circumstances in Animal Houses: What, Why and How

M. Hautala

Department of Agricultural Sciences, University of Helsinki, Finland
e-mail: mikko.hautala@helsinki.fi

Abstract:

The indoor air of the animal house has to be of such quality that the animal, the human being and the building should feel well. It means suitable temperature without moisture and gas, microbe and dust contents which should be low enough. The objective of our studies is to create general physical-chemical models for the ventilation and temperature of animal houses as the function of factors which affect micro climate (temperature, moisture, gases, dust, microbes, mould) and the heat balance of the animals. The optimal climate given by the models is achieved by the right ventilation. A system which is automatic or gives alarms and can be used to carry out the optimum conditions of the animal buildings in as stable a way as possible is needed. For this purpose reasonable and reliable sensors which measure the right factors are needed. So the results of sensors can be used for model based control of the ventilation in which case one can switch to the modelling adjustment in which more quantities can be simultaneously used and in such a way the quality of the indoor air of animal houses can be improved by the adjustment of only one quantity (temperature or moisture or carbon dioxide or other gas).

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68-73 M. Heinloo and J. Olt
A Novel Manipulator for a Stone Protector of Stony Soil Tillage Implement
Abstract |
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A Novel Manipulator for a Stone Protector of Stony Soil Tillage Implement

M. Heinloo and J. Olt

Estonian University of Life Sciences, 56 Kreutzwaldi Str., EE51014 Tartu, Estonia
e-mail: Mati.Heinloo@emu.ee; Jyri.Olt@emu.ee

Abstract:

This paper studies a novel manipulator for a stone protector of stony soil tillage implement. According to the virtual reality technology based method, the composition technology of the virtual model of the novel manipulator is described in detail. This virtual model is used for the compilation of a video clip which simulates the motion of the model. The obtained results and a special computer program, realizing the virtual reality technology based study of the working process of the novel manipulator, can be useful for real time manipulator designers.

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74-78 R. Ilves, V. Mikita, Ü. Traat and A. Gregor
Common Rail Diesel Feed System Diagnosing Technology
Abstract |
Full text PDF (217 kB)

Common Rail Diesel Feed System Diagnosing Technology

R. Ilves¹, V. Mikita¹, Ü. Traat¹ and A. Gregor

¹ Institute of Technology, Estonian University of Life Sciences,
56 Kreutzwaldi Str., EE51014 Tartu, Estonia; e-mail: risto.ilves@emu.ee
² Department of Thermal Engineering in Tallinn University of Technology
Tallinn University of Technology, 116 Kopli Str., EE11712 Tallinn, Estonia;

Abstract:

For testing common rail diesel feed systems, the company responsible for the production has issued test plans that include cycle values and repair technology. This particular article provides the reader with an overview of the common rail diesel feed systems’ changes in cycle value due to control parameters and diagnosing technology that does not use test plans.

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79-85 K. Jansen, M. Luik, V. Viljasoo, J. Ereline, H. Gapeyeva H and M. Pääsuke
Neuromuscular Fatigue Characteristics in Female Painters Following the Working Day
Abstract |
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Neuromuscular Fatigue Characteristics in Female Painters Following the Working Day

K. Jansen¹, M. Luik², V. Viljasoo², J. Ereline¹, H. Gapeyeva¹ H and M. Pääsuke¹

¹ Institute of Exercise Biology and Physiotherapy, University of Tartu
5 Jakobi Str., EE51014 Tartu, Estonia; e-mail: jansen@ut.ee
² Institute of Technology, Estonian University of Life Sciences
56 Kreutzwaldi Str., EE51014 Tartu, Estonia; e-mail: pteh@emu.ee

Abstract:

The aim of this study was to evaluate changes in neuromuscular fatigue characteristics in painters following the working day. The subjects (n = 10) were female painters aged 22-60 years. First the subjects completed a questionnaire and thereafter they performed before and after the working day a 3-minute test of wall painting, in the course of which the electromyographical (EMG) power spectral median frequency (MF) for biceps brachii, trapezius, deltoideus and infraspinatus muscles was measured. The results indicated an increase in subjectively evaluated muscle fatigue compared to the beginning of the working day, whereas the most burdened regions were the arms and shoulders. Objectively estimated muscle fatigue emerged before and after the working day when comparing EMG power spectral MF measured at the beginning and end of the wall painting test. However, this muscle fatigue, evaluated objectively by EMG power spectrum MF slope from biceps brachii, trapezius, deltoideus and infraspinatus muscles, did not differ significantly before and after the working day. This study revealed that painters used different manners of work, whereas the working tool was the same for everyone and no-one had customized it for herself. It is also important to emphasize that 82% of the workers had not been guided in terms of ergonomics. The results of this study can be used by specialists of ergonomics.

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86-98 A. Jasinskas, I. Ulozeviciute and A. Sakalauskas
Evaluation of Physical-Mechanical Properties of Energy Plant Stems and Their Chaff
Abstract |
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Evaluation of Physical-Mechanical Properties of Energy Plant Stems and Their Chaff

A. Jasinskas, I. Ulozeviciute and A. Sakalauskas

Department of Agricultural Machinery, Lithuanian University of Agriculture,
Kaunas-Akademija, 15A Studentu Str., LT-53361 Kauno r., Lithuania; e-mail: aljas@mei.lt

Abstract:

In this article characteristics of willow and topinambour stems used for energy generation are presented. The potential of energy plants grown in Lithuania is reviewed, the methods of plant converting to energy are presented, and different chopping mechanisms are reviewed. The article presents a methodology for evaluation of willow and topinambour stems, their bio-metrical properties and physical-mechanical properties of stem chaff. The experiment results were discussed. Experiments were made on manually cut willow and topinambour stems, which were chopped by drum, disc and screw type choppers. Bio-metrical properties of non-chopped willows and topinambour stems were determined, and the stem chaff physical-mechanical properties such as moisture content, density, angles of natural crumble and fall were evaluated and the investigation of chaff thinness was fulfilled.

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99-106 T. Kabanen
Energy-saving Lighting Installations and Equipment for Multi-tier Narrow-bench Greenhouse Technologies
Abstract |
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Energy-saving Lighting Installations and Equipment for Multi-tier Narrow-bench Greenhouse Technologies

T. Kabanen

Tallinn University of Technology, Tartu College,
78 Puiestee Str., EE51008 Tartu, Estonia
e-mail: toivokabanen@hot.ee

Abstract:

Enterprises of the protected ground or greenhouse horticulture centres must have facilities for the necessary supply of heat, water, electric power, natural and artificial optical radiation. The long-term practice of plant cultivation has shown that in autumn, winter and spring, the basic limiting factor in transparent greenhouses is light.
The radiating mode of the greenhouses is one of the major and power-intensive factors of a microclimate. Therefore, in case of artificial irradiation, it is necessary to pay special attention to the minimization of power consumption, which is associated with the selection of a source, type of irradiation device, reflector configuration and location of the lighting fixtures.
The specific consumption (Sharupich et al., 2005) of power resources in the most common greenhouses in the world, which have one fructifying plant layer in the greenhouse volume, constitutes 40-55 mega-calories per 1kg of the product, which is by 40-45% higher than in the case of the technology of intensive cultivation of the culture, using the method of drop watering. The more productive and more power saving technology, i.e. the so-called Dutch technology is not advantageous in the environmental conditions of Estonia.
The latest research works of scientists have revealed that for the protected ground in the second heat-affected zone, including Estonia, multi-tier narrow-bench hydroponics is a more preferable technology. It allows to make more effective use of the greenhouse volume to ensure a simultaneous fructification of 5 layers, to increase the production yield per area unit by 3.0-4.0 times in comparison with the traditional technology, and to reduce the specific power expenses by approximately 70%.
However, the lighting maintenance of the cutting-edge technology which has a specific arrangement of the plant layers on inclined planes has not been sufficiently elaborated as yet. In particular, there are no technical decisions on the special lighting fixtures ensuring the increase of power efficiency of additional artificial irradiation. Therefore, it is essential to enhance the efficiency of one of the high energy consumption processes of artificial irradiation of the plants considering the spatial specificity of the promising multi-tier narrow-bench hydroponics technology.

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107-114 J. Kers, P. Peetsalu, M. Saarna, A. Viikna, A. Krumme and A.Menind
Preliminary Investigation into Tensile Characteristics of Long Flax Fibre Reinforced Composite Material
Abstract |
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Preliminary Investigation into Tensile Characteristics of Long Flax Fibre Reinforced Composite Material

J. Kers¹, P. Peetsalu¹, M. Saarna¹, A. Viikna², A. Krumme² and A.Menind³

¹ Department of Materials Engineering, Tallinn University of Technology,
Ehitajate tee 5, EE19086 Tallinn, Estonia; e-mail: jaan.kers@ttu.ee
² Department of Polymer Materials, Tallinn University of Technology,
Ehitajate tee 5, EE19086 Tallinn, Estonia
³ Institute of Technology, Estonian University of Life Sciences,
1 Kreutzwaldi Str., EE51014, Tartu, Estonia

Abstract:

Natural fibre composites are materials formed by polymer resin matrix and reinforced with natural fibres mainly formed by cellulose, originating thus from plants, such as hemp, jute, flax, sisal, banana, etc. The advantage of natural fibre materials is their biodegradability and the fact that they are a renewable resource. In Estonia, the most common plant for natural fibre manufacturing has been flax due to its long tradition of cultivation. Flax is currently no longer grown for textile production because of the economic situation, although the weather conditions are very suitable. Nevertheless, flax is still cultivated in small quantities for linseed oil production in Estonia. Experimental methods for manufacturing non-woven industrial textiles like felt and mats from short flax fibres are depicted. Long flax fibres were used as reinforcement in matrix of epoxy resin for experimental manufacturing of natural fibre reinforced composite material. The most important characteristic of all non-woven materials is tensile strength. The results of the tested natural fibre composite materials are presented. The potential fields of application for long flax fibre reinforced composite material are car, marine and windmill industry.

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115-122 J. Korzeniowska and E. Stanislawska-Glubiak
Variation in Response of Five Polish Winter Wheat Cultivars to Foliar Copper Application
Abstract |
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Variation in Response of Five Polish Winter Wheat Cultivars to Foliar Copper Application

J. Korzeniowska and E. Stanislawska-Glubiak

Institute of Soil Science and Plant Cultivation - National Research Institute in Pulawy,
Department of Weed Science and Tillage Systems in Wroclaw,
Orzechowa 61, 50-540 Wroclaw, Poland; e-mail: j.korzeniowska@iung.wroclaw.pl

Abstract:

The aim of the study was to verify whether new, intensive and commonly grown winter wheat cultivars in Poland differ significantly in Cu efficiency. Winter wheat is considered as one of the most sensitive agronomic species to Cu deficiency. Copper fertilization of wheat seems to be a necessity in our country due to common Cu deficiency in Polish soils.
In 2004-2006, three field experiments were conducted in the Experimental Station Osiny in Eastern Poland, where the response of five winter wheat cultivars to foliar copper application was tested. Copper was applied in the form of CuSO4·5H2O at a rate of 305 g ha-1 Cu. Fertilization was performed in spring during the full tillering stage of growth. Analysis of variance was used for statistical calculations. The means were compared using Tukey’s test.
It was demonstrated that the five cultivars responded differently to the Cu fertilization, with a medium content of this element in soil. A single Cu spray caused 5-9% increase in grain yield in three out of the five tested cultivars. The other two cultivars did not show any significant yield increase in response to copper application. Besides, all the cultivars accumulated different quantities of copper in plant tissues, such as shoots and grain. The field trials have proven that winter wheat cultivars are diverse in their nutritional demand for copper. The necessity of winter wheat fertilization with Cu depends not only on the concentration of this nutrient in soil, but also on the tolerance of a given wheat cultivar to copper deficiency.

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123-133 L. Kukk, A. Astover, H. Roostalu, H. Rossner and I. Tamm
The Dependence of Reed Canary Grass (Phalaris arundinacea L.) Energy Efficiency and Profitability on Nitrogen Fertilization and Transportation Distance
Abstract |
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The Dependence of Reed Canary Grass (Phalaris arundinacea L.) Energy Efficiency and Profitability on Nitrogen Fertilization and Transportation Distance

L. Kukk, A. Astover, H. Roostalu, H. Rossner and I. Tamm

Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences,
1 Kreutzwaldi Srt., EE51014 Tartu, Estonia; e-mail: liia.kukk@emu.ee

Abstract:

The increased interest in bio-energy production forces us to consider production sustainability which in turn requires energy crop multi-criteria evaluations. The current study analyzes the dependence of reed canary grass (Phalaris arundinacea L.) energy use efficiency and production profitability on nitrogen fertilization and biomass transportation distance. The study used yield data from reed canary grass field experiments conducted in Estonia in 1968-1976. In reed canary grass production, nitrogen fertilization influences the biomass yield significantly and therefore has an impact on production energy efficiency. Although reed canary grass net energy yield increases continuously (0.15 GJ kg-1) with increasing nitrogen application, the optimum energy use efficiency is reached with 117 kg N ha-1. Increased reed canary grass transportation distance results in an average energy efficiency decrease of 7 MJ GJ-1 km-1. Reed canary grass cultivation for bio-energy
production could be considered at a break-even price of 1.5 EEK kg-1, whereas production profit-loss in this instance depends on nitrogen application. Supplementing profitability analysis with transportation costs results in production net cost and therefore also an increase in break-even price. In the current economic situation the actual buying-up prices do not exceed the production net costs, which is why the negative profitability in reed canary grass bio-energy production must be considered. As the current study evaluated reed canary grass production efficiency on soils with low soil humus content, there is a necessity of extending the study to soils with different fertilizer requirements. The methodology of the current study could be used for evaluating bio-energy production optimization in general despite the results being based on one field experiment.

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134-140 A. Laurs and J. Priekulis
Studies of Operating Parameters in Milking Robots With Selectively Guided Cow Traffic
Abstract |
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Studies of Operating Parameters in Milking Robots With Selectively Guided Cow Traffic

A. Laurs and J. Priekulis

Institute of Agricultural Engineering, Latvia University of Agriculture,
J. Cakstes bulv. 5, Jelgava, LV-3001, Latvia;
e-mail: armins.laurs@promedia.lv; Juris.Priekulis@ llu.lv

Abstract:

Milking robots have been launched on Latvian dairy farms only recently. As the technology differs essentially from that of traditional milking, with the introduction of new technology a range of questions has arisen that have not been topical before. For instance, there has been uncertainty about determining the optimal size of the group of milk cows for robots as well as about planning the robot location and the waiting box.
On installing robots in reconstructed barns, it came out that it was not possible to stick to the designs offered by the companies, and after milking the cows were not sent to the barns but back to the waiting box. As a result, the milked cows had a chance to visit the robots repeatedly. Therefore, a question arose – how much does the repeated visiting of robots influence the effective load.
Moreover, there has been uncertainty about the correct location for the robot in relation to the waiting box using several robots. It was observed that usually in such a case one robot is visited more than the other.
The present research tries to answer these recurring questions. The research results showed that the optimal size of the group of cows served by one robot depends on the average milking time and the time necessary for washing the milk line. If the cows return to the waiting box after milking, the effective load of the robot decreases. The location of the robot in the waiting box in relation to the entrance gate essentially influences the number of visiting one or the other robot per day.

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141-148 J. Lepa, V. Palge, K. Jürjenson, K. Toom, M. Pennar and A. Annuk
Wind Power in Heat Energy Systems
Abstract |
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Wind Power in Heat Energy Systems

J. Lepa, V. Palge, K. Jürjenson, K. Toom, M. Pennar and A. Annuk

Department of Energy Application, Institute of Technology,
Estonian University of Life Sciences, 56 Kreutzwaldi Str., EE51014 Tartu, Estonia
e-mail: jaan.lepa@emu.ee

Abstract:

The article discusses opportunities for the use of wind power plants in order to supply heat to coastal settlements. The possibilities of meeting the needs of heat consumption in the city of Paldiski in Estonia using general data from wind power output serves as an example in the present paper. Monthly electricity and heat consumption graphs and schedules of the Republic of Estonia together with production charts of wind power plants were used as initial data for the research. The investigation of wind energy production charts shows that, due to stochastic peculiarities of the wind, it is especially complicated to match the latter and the electricity consumption charts. There have even been cases, where the dispatcher has been forced to limit wind energy production maxima so that it would not interfere with the work of generators at large power plants. However, satisfactory correlation was revealed between the monthly graphs of both electricity and heat energy overall annual consumption, and wind power production charts. Nevertheless, there are still high deviations, and therefore, in order to use wind energy for heating purposes, powerful storage devices or additional feeding units are necessary to level the fluctuations of electric power produced by wind plants.
The problems related to the production usage of wind power plants in heat and power engineering are to a certain extent less complicated due to the fact that heating systems can be supplemented with additional heat energy storages. Considering the above mentioned issues, the authors suggest a more extensive usage of wind power plants for heating towns and settlements, particularly in cases when production peaks interfere with the work of power systems.
Due to new capacity installations, the overall production of the wind power plants is constantly increasing. Thus, the authors recommend that the maximum power usage coefficient of an operating wind power plant, not their overall production data should be used for analyzing the efficiency of the present power plants and for designing new ones. This will be more correlated with power and heat consumer load curves.

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149-154 A. Lisowski, T. Nowakowski, A. Struzyk and J. Klonowski
Design Project of Row-independent Harvesting Machine for Energetic Plants
Abstract |
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Design Project of Row-independent Harvesting Machine for Energetic Plants

A. Lisowski, T. Nowakowski, A. Struzyk and J. Klonowski

Department of Agricultural and Forest Machinery,
WULS in Warsaw, Nowoursynowska 164, 02-787 Warszawa, Poland
e-mail: aleksander.lisowski@sggw.pl

Abstract:

This is a description of an all-purpose, row-independent machine prototype for harvesting energetic plants in the form of chips or chaff. Patent claim P 385 536 was submitted to the patent office, regarding two versions of cutting adapters: the feeding unit equipped with elastic fingers, or equipped with worm rolls. The machine has modular structure allowing its easy modification, while a hydraulic drive with electro-hydraulic control enables to select the optimal operation parameters of working elements and units under various field conditions. The machine can cut plants with shoot diameter up to 70 mm at the height up to 100 mm, and break them up into particles of 20–60 mm.

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155-164 A. Menind and A. Normak
Study on Grinding Biomass as Pre-treatment for Biogasification
Abstract |
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Study on Grinding Biomass as Pre-treatment for Biogasification

A. Menind¹ and A. Normak²

¹ Institute of Technology, Estonian University of Life Sciences,
56 Kreutzwaldi Str., EE51014 Tartu, Estonia; e-mail: andres.menind@emu.ee
² Institute of Agricultural and Environmental Sciences,
Estonian University of Life Sciences, 5 Kreutzwaldi Str., EE51014 Tartu, Estonia

Abstract:

Six different samples were collected from local farms in Tartu County in Estonia. Based on preliminary results of fibre tests, four samples with different lignin content were chosen for grinding and biogasification experiments. Next, knife mill and laboratory scissors were used for particle size reduction. The knife mill was used with bottom screen sizes 0.5 mm, 4 mm and 10 mm. With scissors the hay was cut into 2…3 cm pieces. Sieve shaker and Easy Sieve software were used for particle distribution analysis. Biogas potential was determined for different hay samples. Cumulative biogas production was calculated by pressure increase in gas phase of bottles according to ideal gas law. We are going to show in what way the cutting impacts biogas yield. Negative correlation between biogas yield, particle size and lignin content is significant for most hay samples analysed.

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165-176 H. Mikkola and J. Ahokas
Energy Management of Future Farms
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Energy Management of Future Farms

H. Mikkola and J. Ahokas

University of Helsinki, Department of Agrotechnology
POB 28, 00014 University of Helsinki; e-mail: Jukka.Ahokas@helsinki.fi

Abstract:

Energy management in agriculture will be of current interest in the near future. Modern agriculture is run by fossil energy and it is unclear how this energy input will be replaced with renewable energy. The year 2008 gave some foretaste how rapidly and how much energy price can rise. Energy saving and exploiting farm’s own energy resources are ways to reduce dependency on oil. Nitrogen fertilizer is the most significant energy input in plant production because ammonia manufacturing is very energy intensive. Crop rotations including legumes, green fertilization, and better manure management are measures to replace synthetic nitrogen. Traditional work chains can be replaced with more energy efficient operations. Direct drilling and grain preservation methods other than drying are good examples. Animal housing requirements for inside temperature and air quality define the demand for heating and ventilation. Along with milking and milk cooling, they are the most significant energy inputs in animal production. Animal welfare has to be respected always; however, by means of heat recovery and biogas production it is possible to save energy and exploit energy from manure. Energy should not be considered as a separate question; on the contrary, a farm has to be considered as a whole and as a part of the rest of the society. Better energy management and plant nutrient recycling are combined issues and require more comprehensive approach than it has been the case.

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177-191 J. Miljan and M. Kiviste
Estimation of Residual Flexural Capacity of Existing Precast Concrete Panels by Visual Inspection
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Estimation of Residual Flexural Capacity of Existing Precast Concrete Panels by Visual Inspection

J. Miljan¹ and M. Kiviste²

¹ Institute of Forestry and Rural Engineering, Estonian University of Life Sciences,
Kreutzwaldi 5, 51014 Tartu, Estonia; e-mail: jaan.miljan@emu.ee
² Institute of Forestry and Rural Engineering, Estonian University of Life Sciences,
Kreutzwaldi 5, 51014 Tartu, Estonia; e-mail: mihkel.kiviste@emu.ee

Abstract:

The influence of visual assessment grade on the residual flexural capacity of 46 existing precast concrete ribbed panels was studied. Before the tests, the panels were assessed on a 6-point rating scale according to visually distinguishable corrosion deterioration. All panels, the ultimate load of which was lower than the control load, received grade 0 on visual rating scale. Consequently, attention should be paid to panels where the concrete cover of longitudinal reinforcement has spalled (grade 0), which could be a sign of decreasing load capacity. The majority of panels with grade 0 exhibited larger deflections under load than panels with higher grades. Of the 46 panels tested flexural ductile failure was noticed in 36 panels.

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192-200 K. Oha, V. Viljasoo and E. Merisalu
Prevalence of Musculoskeletal Disorders, Assessment of Parameters of Muscle Tone and Health Status among Office Workers
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Full text PDF (111 kB)

Prevalence of Musculoskeletal Disorders, Assessment of Parameters of Muscle Tone and Health Status among Office Workers

K. Oha¹, V. Viljasoo¹ and E. Merisalu²

¹ Institute of Technology, Estonian University of Life Sciences,
64 Kreutzwaldi Str., EE51014 Tartu, Estonia; e-mail: kristel.oha@emu.ee; pteh@emu.ee
² Institute of Public Health, The University of Tartu,
19 Ravila Str., EE50411 Tartu, Estonia; e-mail: eda.merisalu@ut.ee

Abstract:

Our way of life has changed considerably because of increased computer usage. Usually people do not think about links between computer work, fatigue and musculoskeletal disorders.
The aim of the study was to examine the prevalence of musculoskeletal pains, assess the musculoskeletal status and general health condition and to analyze associations between these indices. The methods of the study were based on a questionnaire, myometry and dynamometry. The most common musculoskeletal pains among office workers were neck pain (51.5%) and lower back pain (41.7%). Pains in the hands/wrists (34.5%), knees (29.9%) and elbows (14.6%) were less reported. The measurements of m. trapezius showed that the values of the tone were higher in the afternoon. Also, the most values of m. erector spinae were higher in the afternoon. The measurements of the grip strength showed a decrease in strength during the day.
The study confirmed the results of many earlier studies that the most common pains among office workers are neck and lower back pains. Office work is a burden especially for the m. trapezius and also for the m. erector spinae.

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201-207 P. Peetsalu,, J. Resev, A. Ruus, A. Menind, Jaan Kers, S. Sepper and J. Olt
Preliminary Investigation into Mechanical Properties of Clay Reinforced with Natural Fibres
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Preliminary Investigation into Mechanical Properties of Clay Reinforced with Natural Fibres

P. Peetsalu¹,², J. Resev², A. Ruus², A. Menind³, Jaan Kers¹, S. Sepper¹ and J. Olt³

1 Department of Materials Engineering, Tallinn University of Technology
2 Tartu College, Tallinn University of Technology
³ Institute of Technology, Estonian University of Life Sciences,
56 Kreutzwaldi Str., EE51014 Tartu, Estonia
e-mail: jaan.kers@ttu.ee, andres.menind@emu.ee

Abstract:

Nowadays natural materials are popular and favoured in civil engineering. At the same time it is important to use renewable and local materials which have low CO2 production. One of these materials is clay reinforced with natural fibres. For production purpose it is necessary to find the natural fibres which have suitable properties and can be grown in large amounts. This kind of fibre is flax, which produces a strong fibre. The article focuses on flax as a reinforcing natural fibre in clay which can be used for walls and undercoat plasters. Flax is milled to fractions with different length and mixed with clay, sand and water. Dried clay mix cube’s compressive strength is measured. Finally the best fraction as for flax length and amount is suggested for future experiments to find out the best fraction of fibres for clay with good compressive strength.

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208-215 V. Pirs, D. Berjoza, G. Birzietis, and I. Dukulis
Fuel Consumption Studies of Spark Ignition Engine Using Blends of Gasoline with Bioethanol
Abstract |
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Fuel Consumption Studies of Spark Ignition Engine Using Blends of Gasoline with Bioethanol

V. Pirs, D. Berjoza, G. Birzietis, and I. Dukulis

Motor Vehicle Institute, Faculty of Engineering, Latvia University of Agriculture,
5 J. Cakstes boulv., Jelgava, LV-3001, Latvia; e-mail: vilnis.pirs@llu.lv;
dainis.berjoza@llu.lv; gints.birzietis@llu.lv; ilmars.dukulis@llu.lv

Abstract:

The increased oxygen content in blends of gasoline with bioethanol causes the necessity for increasing fuel supply to the engine. Car oxygen sensor, reacting to the presence of oxygen in the exhaust gases, increases the amount of injected fuel. Consequently, the higher concentration of bioethanol in fuel blends usually also increases fuel consumption. This study explores how an increase in bioethanol concentration in fuel blends affects the standard car’s fuel consumption and determines which elements of the system limit the maximum possible concentration of bioethanol in the blend with gasoline.

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216-225 V. Poikalainen, J. Praks, E. Kokin, A. Aland, I. Veermäe, S. Peets, J. Ahokas, M. Pastell, M. Hautala, D. Berckmans, C. Bahr, and D. Miljkovic
Elaboration of Basic Methods for Automatic Analysis of Cows’ Gait
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Elaboration of Basic Methods for Automatic Analysis of Cows’ Gait

V. Poikalainen¹, J. Praks¹, E. Kokin¹, A. Aland¹, I. Veermäe¹, S. Peets¹, J. Ahokas², M. Pastell², M. Hautala², D. Berckmans³, C. Bahr³, and D. Miljkovic³

1 Estonian University of Life Sciences, 1 Kreutzwaldi Str., EE51014 Tartu, Estonia
e-mail: vaino.poikalainen@emu.ee
² University of Helsinki, Department of Agrotechnology, P.O. Box 28 (Koetilantie 3),
00014 Helsinki, Finland; e-mail: Jukka.ahokas@helsinki.fi
³ Division Measure, Model & Manage Bioresponses (M3-BIORES), Katholike Universiteit
Leuven, Kasteelpark Arenberg 30, B-3001 Leuven, Belgium
e-mail: Claudia.Bahr@biw.kuleuven.be

Abstract:

Two different methods for automatic registration and analysis were used to produce data for comparison and analysis of lame and healthy animals’ gait in Estonia. A walk over mat with two quazi-piezoelectric sensors was elaborated and tested in co-operation with University of Helsinki. Preliminary analysis indicates that lameness can be seen as asymmetric gait and thus the quazi-piezoelectric walk-over mat is a promising tool for automatic leg problem detection.
A video-system was introduced to record walking pattern of cows in co-operation with Catholic University of Leuven. For video recordings three cameras were used to obtain top, side and leg views with StreamPix software video-signal capture. Possibilities of image based separation of dairy cows with real time vision system and preliminary settlement of this was developed. A model-based motion scoring system is proposed for derivation of image parameters needed for lameness detection.
About 600 cows once a week were investigated in a large dairy farm during four months’ period.
Dairy cows’ gait pattern was recorded with the aid of quazi-piezoelectric walk-over mat and video-system. Preliminary lameness scoring was performed in the cowshed visually by two experts. These scoring results were later specified by expert commission on the basis of video-recordings. Lameness scores (according to Sprecher et al) were assigned as follows: 1–6,012 cases, 2–1,181 cases, 3–522 cases, 4–105 cases and 5–37 cases from total 10,653 cases. The database of cows’ identification numbers, lameness scores and disordered legs description was created, that allows synchronization of walk-over mat signals data and video files.

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226-235 V. Põder, T. Peets, K. Toom and A. Annuk
The Estimation of Wind Lull and Consumption Factor Influence on Autonomous Wind Energy System
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The Estimation of Wind Lull and Consumption Factor Influence on Autonomous Wind Energy System

V. Põder, T. Peets, K. Toom and A. Annuk

Department of Energy Application, Institute of Technology,
Estonian University of Life Sciences, 56 Kreutzwaldi Str., EE51014 Tartu, Estonia
e-mail: vahur.poder@emu.ee

Abstract:

Due to the stochastic output of wind generators, some kind of storage device will be necessary to ensure a constant energy supply by an autonomous energy system. The necessary storage capacity depends on wind data and consumption factor. The latter describes the ratio between average production capacity and average usage capacity. In addition to average wind speed, the frequency and duration of windless periods must be considered as well. The concept of energy lulls has been outlined to describe the influence of duration, frequency and distribution of wind less periods on a wind energy system. Location has strong influence on energy lull length; the difference in average duration between a coastal area and inland is more than two fold. Weibull distribution can be used to describe the probability of energy lulls.

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236-254 K. Ritslaid, A. Küüt and J. Olt
State of the Art in Bioethanol Production
Abstract |
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State of the Art in Bioethanol Production

K. Ritslaid¹, A. Küüt² and J. Olt²

¹ Estonian Aviation Academy,
58A Kreutzwaldi Str., EE51014 Tartu, Estonia;
² Institute of Technology, Estonian University of Life Sciences,
56 Kreutzwaldi Str., EE51014 Tartu;
e-mail, arne.kyyt@emu.ee

Abstract:

The objective of the present study is to provide an overview of available literature on problems and potential solutions in bioethanol production. The preparation of an overview of bioethanol as motor fuel requires knowledge of its chemical-physical properties and different production methods. The study points out the most popular opinions and test results to characterise the production of bioethanol. This overview considers potential methods for producing ethanol and production technologies suitable for ethanol as motor fuel, especially most recent achievements in converting carbohydrates into ethanol.

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255-262 A. Ruus, V. Poikalainen, J. Praks, I. Veermäe, F. Teye, M. Hautala and J. Ahokas
Indoor Air Temperature and Ventilation in Uninsulated Loose Housing Cowsheds with Different Types of Non-transparent Roofing in Hot Summer
Abstract |
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Indoor Air Temperature and Ventilation in Uninsulated Loose Housing Cowsheds with Different Types of Non-transparent Roofing in Hot Summer

A. Ruus¹, V. Poikalainen², J. Praks², I. Veermäe², F. Teye³, M. Hautala⁴ and J. Ahokas⁴

¹ Tartu College, Tallinn University of Technology,
78 Puiestee Srt., EE51008 Tartu, Estonia, e-mail: aime.ruus@ttu.ee
² Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life
Sciences, 62 Kreutzwaldi Str., EE51014 Tartu, Estonia; e-mail: vaino.poikalainen@emu.ee
³ Plant Production Research, MTT Agrifood Research Finland
MTT, Vakolantie 55, FIN03400, Vihti, Finland; e-mail: kwame@mappi.helsinki.fi
⁴ Department of Agrotechnology, University of Helsinki,
Koetilantie 3, FIN00014 Helsinki, Finland; e-mail: Jukka.Ahokas@helsinki.fi

Abstract:

As the indoor temperature of uninsulated cowsheds is in correlation with outdoor temperature, it may happen that indoor temperatures in cowsheds soar in hot summer. Roof temperature and spatial distribution of indoor air temperature at 1m (cow level) was studied in 8 uninsulated cowsheds with three different types of roof – non-asbestos cement sheets (4 cowsheds), metal (2 cowsheds) and insulated with 25 mm mineral wool plate (2 cowsheds) at outdoor air temperatures 26.8…32.0°C in at least 25 points of the cowshed. All openings were open in the cowsheds.
Roof (indoor surface) temperature values of 47.1°C were recorded as highest at non-asbestos cement roof in outdoor air temperature of 30°C. The average indoor surface temperature of the insulated roof (28°C) was about as high as outdoor air temperature (29°C).
Average indoor temperature in cowsheds varied 27.6-29.7°C. Smallest indoor-outdoor air temperature difference (t) was 0.8°C and occurred at lowest outdoor temperature (26.8°C). The biggest t of -2.3°C occurred at highest outdoor temperature (32°C). If the roof was insulated, t varied -0.5-1.1°C. In four cowsheds with non-asbestos cement sheet roof, t of 0.8…-1.9°C was recorded. In cowsheds with metal sheet roof, t of – 1.2… -2.3°C was recorded.
Standard deviation of indoor temperatures at the measurement points s (describes the ventilation efficiency) was s=0.59…0.84 in the cowsheds with insulated roof and s=0.46…0.66 in the uninsulated ones. The ventilation in cowsheds was good and air moving schemes uniform.
As a result of the investigation, the following conclusion can be made: indoor air temperature and ventilation efficiency in hot summer days are not influenced by roof material (non-transparent) or the presence of insulation.

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263-271 E. Stanislawska-Glubiak and J. Korzeniowska
Yield of Winter Wheat Grown under Zero and Conventional Tillage on Different Soil Types
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Yield of Winter Wheat Grown under Zero and Conventional Tillage on Different Soil Types

E. Stanislawska-Glubiak and J. Korzeniowska

Institute of Soil Science and Plant Cultivation, National Research Institute in Pulawy,
Department of Weed Science and Tillage Systems in Wroclaw,
Orzechowa 61, 50-540 Wroclaw, Poland; e-mail: e.glubiak@iung.wroclaw.pl

Abstract:

In three-year field trials, conducted in West Poland, the growth and development of winter wheat grown under zero tillage (ZT) and conventional tillage (CT) methods on four soils were investigated. The soils were different mainly in grain fraction distribution and content of organic matter. The tested soils were sandy loam (SL), loamy sand (LS-1, LS-2) and sand (S). In GPS-fixed sites, in ZT and CT fields, yield of aerial part biomass in four growth stages: stem elongation, second node, and heading and inflorescence phases, was compared. In addition, yields of grain and straw were tested. On medium and coarse textured soils (SL, LS-1, LS-2), more biomass was produced by wheat under CT than ZT, but on very coarse textured soil (S), the biomass yields obtained from wheat growing under both soil tillage methods were identical. On medium textured soils and on coarse textured (LS-1) soil, wheat under CT contained more N and P as well as much more Ca and Mg in tissues than under ZT. In contrast, on the other coarse textured (LS-2) soil and on very coarse textured soil, wheat plants under ZT were generally characterized by identical or slightly higher nutrient content than plants under CT. Despite periodic fluctuations in biomass yields between ZT and CT for particular growth stages of wheat, the yields of grain and straw were the same for both soil tillage methods, irrespective of the soil type.

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272-279 V. Zagorska and A. Ilsters
Possibilities of Heat Exchanger Use in Pigsty Ventilation Systems
Abstract |
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Possibilities of Heat Exchanger Use in Pigsty Ventilation Systems

V. Zagorska¹ and A. Ilsters²

¹ Institute of Mechanics, Latvia University of Agriculture,
Liela iela 2, LV-3000, Jelgava, Latvia; e-mail: vzagorska@gmail.com
² Research Institute of Agricultural Machinery, Agency of Latvia University of Agriculture,
Instituta Street 1, Ulbroka, LV-2130, Riga district, Latvia

Abstract:

There is a considerable increase in energy demand during autumn-winter conditions due to the necessity to keep optimal microclimatic conditions in pigsties. When heat exchangers are used in the ventilation systems on the premises of pigsties, clean and cold air (in the autumn-winter period) gets an amount of heat energy from unclean but warm air. Up to now heat exchangers have not been used widely in Latvia and therefore there is no experience about the use of heat exchangers for microclimatic stability in piggeries. The goal of the investigation is to clear out the possibilities of heat exchanger use at farms in Latvian climatic conditions.
The article deals with experimental results obtained from experiments about plate counter-flow heat exchanger models with plastic cellular boards (HE PVC) and plastic plates (WVT 120K) as heat transfer surfaces. Operational parameters which describe the energy efficiency of heat exchangers were calculated – power of recovered heat energy œ, heat transfer coefficient, and coefficient of performance (COP) by recovered heat. The parameters were analyzed depending on outside air temperature in an interval from +6 C to -16 C.
In the weather conditions of Latvia it is important to achieve heat transfer as completely as possible, widening thus the interval of heat deficit coverage towards lower outside air temperature.

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280-286 I. Ziemelis, H. Putans and L. Kancevica
Investigation of Solar Collector Irradiated from Both Sides
Abstract |
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Investigation of Solar Collector Irradiated from Both Sides

I. Ziemelis, H. Putans and L. Kancevica

Research Institute of Agricultural Machinery, Latvia University of Agriculture,
Institute Street 1, LV–2130, Ulbroka, Riga region, Latvia
e-mail: Imants.Ziemelis@llu.lv; Liene.Kancevica@llu.lv

Abstract:

The ordinary flat plate solar collector receives solar radiation only from one side of its surface. Another side is covered with a heat barrier. The solar collector with reflectors has been developed and examined to track the sun. The absorber of this type of a collector was irradiated from both sides. The experimentally obtained energetic parameters of the collector tracking the sun have been compared to those of the ordinary flat plate solar collector. In order to complete the experiment, a special stand has been developed. The experimental investigation has been carried out at the intensity of radiation 2,000, 1,000 and 500 W m -2 in different combinations. The temperature has been measured in certain points of different parts of the collector by several thermocouples. With the aid of a multi-meter, the obtained results were collected to the memory of a computer, and later processed and analyzed. When a collector surface is tracking the sun, the heat energy produced by the collector is 1.4 to 1.5 times higher in comparison with a stationary solar collector of the same size. A solar collector tracking the sun and irradiated from both sides depending on the reflection quality of the reflector’s material is able produce about 2.5 times more heat energy then a stationary flat plate solar collector irradiated only from one side.

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287-300 Ü. Traat, A. Küüt and J. Olt
Specific Features of Establishment and Maintenance of Tractor Fleet in a Typical Estonian Agricultural Holding
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Specific Features of Establishment and Maintenance of Tractor Fleet in a Typical Estonian Agricultural Holding

Ü. Traat, A. Küüt and J. Olt

Institute of Technology, Estonian University of Life Sciences,
56 Kreutzwaldi Str., EE51014 Tartu, Estonia
e-mail: ylo.traat@emu.ee; arne.kyyt@emu.ee; jyri.olt@emu.ee

Abstract:

In spite of the high reliability of modern tractors, they are no perpetuum mobiles and need at times designated by the manufacturer’s technical condition regular diagnostics, the diagnostic results being determined on the basis of work and the amount of content, technical maintenance and repair, if necessary. This study examines the design and maintenance problems of an Estonian representative farm tractor compared to similar indicators in the Republic of Latvia. The outlines of a typical company are based on expert opinions. These indicators have been analyzed and compared to those of the whole Estonia at the level of one particular farm in real terms. The machine/tractor maintenance-related economic and technical indicators have been set to ensure the reliability of machine/tractor use in competitive agricultural production. The investigation examines the company’s actual use of machine/tractor, tractor upkeep and methods for determining the composition of the qualitative and quantitative indicators.

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