Tag Archives: modelling.

xxx A. Aboltins, J. Priekulis, B. Aboltina and L. Melece
Effect of slurry lagoon redesign on reduction of ammonia emission during livestock manure storage
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Effect of slurry lagoon redesign on reduction of ammonia emission during livestock manure storage

A. Aboltins¹*, J. Priekulis¹, B. Aboltina² and L. Melece³

¹Latvia University of Agriculture, Institute of Agriculture Machinery, Cakstes blvd. 5, LV-3001 Jelgava, Latvia
²Latvia University, Faculty of Physics and Mathematics, Zellu str. 25, LV-1002 Riga, Latvia
³Institute of Agricultural Resources and Economics, Struktoru str. 14, LV-1039 Riga, Latvia
*Correspondence: aivars.aboltins@llu.lv

Abstract:

In accordance with the international and EU aims to reduce emissions of ammonia and other air pollution substances farm manure management, including its storage, especially for the animal breeding sector, is one of the most essential stages. One of the preventing steps is covering of the slurry lagoons. The most effective – hard covering can be provided only after the lagoon is constructed. The aim of the research: to develop methodology for calculations of emission reducing lagoon design volume and surface area. In the result of the theoretical research the possibilities of reducing the reflection surfaces at the same capacity of the lagoon have been discovered, as well as the changes of the reflection surface area, if instead of one lagoon several lagoons with less volume are installed and sequential filling of these lagoons is ensured. The article presents the calculation algorithms obtained during the research and recommendations for construction of low emission lagoons.

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1232–1240 Z. Vondrášek
Numerical Modelling of Transient Phenomena in a Synchronous Machine
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Numerical Modelling of Transient Phenomena in a Synchronous Machine

Z. Vondrášek

1Czech University of Life Sciences Prague, Faculty of Engineering, Department of Electrical Engineering and Automation, Kamýcká 129, CZ 16521 Praha 6 – Suchdol, Czech Republic; e-mail: vondrasek@tf. czu.cz

Abstract:

The present contribution deals with the idea of identification of electromagnetic transient phenomena pages in a synchronous machine – namely of distant short circuits – by numerical modelling. Phenomena in AC windings of a synchronous machine (stator) have a backswing effect on the phenomena in DC windings – namely the excitation one. Concerned is namely the current stress of the excitation circuit during the transient phenomenon. The computer model is created in the Famulus- vers. 3 – environment. The time behaviour of AC circuit currents in components d, q and the excitation circuit is monitored on the example of a 3-pole distant short circuit in a synchronous machine (via the impedances of connecting elements). The results are compared of models with a simpler structure (one damper circuit in the rotor) with those with a more complicated structure (two damper circuits in the rotor). 

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689–710 V. Bulgakov, V. Adamchuk, M. Arak, V. Nadykto, V. Kyurchev and J. Olt
Theory of vertical oscillations and dynamic stability of combined tractor-implement unit
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Theory of vertical oscillations and dynamic stability of combined tractor-implement unit

V. Bulgakov¹, V. Adamchuk², M. Arak³, V. Nadykto⁴, V. Kyurchev⁴ and J. Olt³*

¹National University of Life and Environmental Sciences of Ukraine, 15, Heroyiv Oborony Str., UK 03041 Kyiv, Ukraine
²National Scientific Centre, Institute for Agricultural Engineering and Electrification, 11, Vokzalna Str., Glevaкha-1, Vasylkiv District, UK 08631 Kiev Region, Ukraine
³Estonian University of Life Sciences, Kreutzwaldi 56, EE51014 Tartu, Estonia
⁴Tavria State Agrotechnological University of Ukraine, Khmelnytskoho pr. 18, Melitopol, UK 72312 Zaporozhye region, Ukraine
*Correspondence: jyri.olt@emu.ee

Abstract:

 Currently, throughout the world quite extensive use is made of combined tractor-implement units, which are capable of performing several process operations in the same pass. At the same time, the state-of-the-art ploughing and general-purpose tractors that can carry as front- so rear-mounted implements and accordingly feature both the front and rear PTOs, also able to travel efficiently as forward so in reverse gear, are most suited for the performance of such operations. Authors developed and successfully tested a combined tractor-implement unit on the basis of a wheeled ploughing and general-purpose tractor, which can in one pass efficiently chop the after harvesting crop residues with a front-mounted rotary chopper and simultaneously perform tillage with a rear-mounted plough. The aim of this study is the elaboration of the theoretical basis for the process of vertical oscillation of the combined ploughing and chopping tractor-implement unit and the validation of its dynamic stability in the longitudinal and vertical plane. The research has been performed with the use of the methods of designing the analytical mathematical models of functioning of agricultural machines and machine assembly units based on the theory of tractor, the vibration theory, the theory of automatic control and dynamic stability and the methods of computer programme construction and PC-assisted numerical computation. The dynamics of the said unit have been studied basing on the analysis of the amplitude frequency characteristics of the unit as a dynamic system responding to external perturbations appearing in the form of soil surface irregularities. Following the results of the undertaken analytical study, first the equivalent schematic model of the discussed combined tractor-implement unit in the longitudinal and vertical plane was developed, the unit’s characteristic points were defined, the linear and angular displacements specified and acting forces applied. Each pneumatic-tyre wheel of the unit represented by its elastically damping model had point contacts with the soil surface irregularities defined by the respective elevations. Using the original dynamic equations in the form of the Lagrange equations of the second kind, first we defined the generalised coordinates and the formulae for the kinetic and potential energy, dissipation functions and generalised forces, then, after performing the necessary transformations, we set up the system of four differential equations, which described the motion of the dynamic system under consideration. Further, we applied the Laplace transformations to the obtained differential equation system, which provided for obtaining the system of equations in the operator form and preparing them for the representation suitable for PC-assisted numerical calculations with the use of the developed computer programme. In accordance with the numerical computation results, graphs were plotted for the amplitude and phase frequency response characteristics of the tractor’s vertical oscillations at different stiffness coefficients of its steering wheels, the amplitude frequency response characteristics of the chopper’s oscillations depending on its mass and its support wheel tyres’ stiffness coefficient as well as the characteristics of the plough’s oscillations at different stiffness coefficients of its pneumatic-tyre ground support wheel.

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556–568 J. Prchalová, H. Čížková, R. Ševčík, K. Hanušová and A. Rajchl
Evaluation of shelf-life of fruit baby food
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Evaluation of shelf-life of fruit baby food

J. Prchalová, H. Čížková, R. Ševčík, K. Hanušová and A. Rajchl*

Department of Food Preservation, University of Chemistry and Technology Prague,
Technická 5, CZ 160 28 Prague 6, Czech Republic
*Correspondence: ales.rajchl@vscht.cz

Abstract:

Fruit baby food is an important food source in infant nutrition. This ambient stable product is processed using heat treatment and can be stored for one or more years at ambient temperature. An accelerated shelf-life storage test of fruit baby food was carried out. Sets of samples were stored at various storage temperatures (40, 55, 70 and 90 °C) for 3 weeks. Selected markers were followed and correlated with sensory evaluation during the storage. The markers were: DPPH, total phenols, ascorbic acid, 5-HMF, furfural and colour (expressed as L, a*, b* and nE). Kinetic data (reaction rate constants, activation energies, Q10, z values) were calculated. The aim of the paper was to evaluate shelf-lives of fruit baby food. The colour parameters, especially nE, seem to be a robust criterion which could be used to predict shelf-lives of fruit baby food.

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1165-1192 V. Bulgakov, V. Adamchuk, M. Arak and J. Olt
Theory of vibration-assisted sugar beet root lifting
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Theory of vibration-assisted sugar beet root lifting

V. Bulgakov¹, V. Adamchuk², M. Arak³ and J. Olt³⋅*

¹National University of Life and Environmental Sciences of Ukraine 15, Heroyiv Oborony Str., UK03041 Kyiv, Ukraine
²National Scientific Centre, Institute for Agricultural Engineering and Electrification, 11, Vokzalna Str., Glevaкha-1, Vasylkiv District, Kiev Region, UK08631, Ukraine
³Estonian University of Life Sciences, Institute of Technology, 56 Kreutzwaldi Str., EE51014 Tartu, Estonia;
*Correspondence: jyri.olt@emu.ee

Abstract:

The vibration-assisted lifting of sugar beet roots from the soil has been gaining increasingly wide use worldwide and the majority of sugar beet harvesting machinery manufacturers produce beet harvesters equipped with just such kind of lifting units. In such units the priorities are low tractive resistance, the high quality of harvesting in terms of undamaged side surfaces of beet root bodies and intact tail parts as well as the high degree of their initial cleaning from the stuck soil. However, the parameters of the oscillatory processes generated by the vibrational lifting units used on the majority of sugar beet harvesting machinery in the market have rather average values appropriate for relatively favourable harvesting conditions (soft loose soil, beet root sizes close to the average, properly lined up planting rows etc.). But when the harvesting conditions deviate from their favourable values (especially in case of dry and strong soil), the vibrating lifters start performing the digging process with significant damage to the beet roots (breaking and tearing off the tail parts), their power consumption rises excessively sharply, the unit vibration drives prove to be unreliable. The literature source analysis has shown that any sufficiently detailed, comprehensive and dependable theory of direct beet root lifting from the soil is virtually absent. Thus, the aim of this research study has been to work out such a theoretical basis for the process of vibration-assisted beet root lifting, which will allow to calculate, in accordance with the harvesting parameters, the optimal design and kinematic parameters of the process ensuring the high quality of harvesting. A new theory has been developed, which describes the process of direct vibration-assisted beet root lifting performed under the effect of the vertical disturbing force and the pulling force, imparted to the root by the lifting unit. The obtained system of differential equations has made it possible to establish the law of motion of the beet root in the process of its direct vibration-assisted lifting and perform PC-based numerical calculations, which provide the basis for determining optimal kinematic modes of operation and design parameters of vibrational lifting units subject to the condition of maintaining sugar beet roots intact when harvesting them.

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863-878 T. Antal
Comparative study of three drying methods: freeze, hot air- assisted freeze and infrared-assisted freeze modes
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Comparative study of three drying methods: freeze, hot air- assisted freeze and infrared-assisted freeze modes

T. Antal

College of Nyíregyháza, Institute of Engineering and Agricultural Sciences, Department of Vehicle and Agricultural Engineering, Kótaji Str. 9–11., H-4400 Nyiregyhaza, Hungary; e-mail: antalt@nyf.hu

Abstract:

The dehydration tests were conducted at three drying methods to evaluate the drying curves and the energy uptake. Apple (Malus domestica L.) cubes were dried under different processing conditions applying freeze drying (FD), freeze drying assisted by hot air and freeze drying assisted by infrared radiation. Control samples were produced using regular freeze drying without the pre-drying. Hot air combined with freeze drying (HAD-FD) at 60 and 80°C air temperatures was investigated. The infrared-freeze drying (IR-FD) is a relatively new processing method. The Idared apple cubes were dried with 5 kW m-2 IR power intensity. It was observed that the infrared power level and hot air temperature affected the drying rate and time of freeze drying. The infrared radiation heating had a higher drying rate than hot air during the pre-dehydration. The water activity, colour, firmness and rehydration ratio (RR) of finished products were measured. The dried material produced with IR-FD had desirable colour, higher rehydration rate and lower firmness than dried by HAD-FD ones. The quality of single-stage FD samples was close to IR-FD materials. It was observed that the IR-FD method drastically decreased the energy consumption, compared to FD and HAD-FD drying treatments. The mathematical models such as Henderson-Pabis and third-degree polynomial are used to describe the drying kinetics of food material. It was found that those mathematical models performed adequately in predicting the changes of moisture ratio.

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33-45 V. Bulgakov, V. Adamchuk, J. Olt and D. Orszaghova
Use of Euler equations in research into three-dimensional oscillations of sugar beet root during its vibration-assisted lifting
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Use of Euler equations in research into three-dimensional oscillations of sugar beet root during its vibration-assisted lifting

V. Bulgakov¹, V. Adamchuk², J. Olt³⋅* and D. Orszaghova⁴

¹National University of Life and Environmental Sciences of Ukraine, 15, Heroyiv Oborony Str., 03041 Kyiv, Ukraine
²National Scientific Centre ‘Institute for Agricultural Engineering and Electrification’, 11, Vokzalna Str., Glevaкha-1, Vasylkiv District, 08631 Kiev Region, Ukraine
³Estonian University of Life Sciences, Institute of Technology, Kreutzwaldi 56, EE51014 Tartu, Estonia; *Correspondence: jyri.olt@emu.ee
⁴Slovak University of Agriculture in Nitra, 2, Trieda Andreja Hlinku, 949 76 Nitra, Slovakia

Abstract:

Following the results of the research into the physical process of the vibratory interaction between the digging tool and the beet root, it has been found that the latter, while standing in soil, i.e. amid an elastic medium, has strong attachment to the soil in its lower (the densest and driest) part, which virtually implies one conventional fixed point. This finding provides the basis for examination of the three-dimensional motion of the beet root’s body during its lifting from the ground in case of its asymmetric interaction with one of the shares of the vibrating digging tool. We have studied the gyration of the beet root’s body about a point initiated by its interaction with the inclined face of the vibrating digging tool share that makes oscillatory movements in the longitudinal vertical plane. The aim of the study is to establish the values of the angular displacements of the root’s body at the moment of its getting in asymmetric contact with the vibrating digging tool followed by the breaking of its bonds with the surrounding elastic medium, i.e. to develop a new mathematical model of the vibration-assisted digging of a beet root out of the soil. Basing on the use of the original equations of Euler, a new differential equation system has been obtained, which facilitates the analytical treatment of the mentioned work process. That system of differential equations for the three-dimensional oscillations of the root caused by the action of a perturbing force comprises three dynamic and three kinematic equations. It is a determined system, which makes possible its solution, i.e. the numerical modelling of the process of root lifting from the ground under different digging conditions, because it includes all necessary parameters of the vibrating digging tool, the sugar beet root and the soil surrounding it.

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167-174 A. Normak, J. Suurpere, K. Orupõld, E. Jõgi and E. Kokin
Simulation of anaerobic digestion of cattle maure
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Simulation of anaerobic digestion of cattle maure

A. Normak¹, J. Suurpere¹, K. Orupõld¹, E. Jõgi² and E. Kokin²

¹Institute of Agricultural and Environmental Sciences, Estonian University of Life
Sciences, Kreutzwaldi 5, EE51014 Tartu, Estonia; e–mail: argo.normak@emu.ee
²Institute of Technology, Estonian University of Life Sciences, Kreutzwaldi 56,
EE51014 Tartu, Estonia

Abstract:

IWA Anaerobic Digestion Model No.1 (ADM1) was used to simulate the anaerobic digestion process of cattle slurry. The model was applied to 200 l single stage completely stirred tank reactor. The simulation results of pH, biogas flow rate, acetate and methane concentration were under study. Ammonia inhibition constant was optimized during this study to improve modelling results compared to measurements of acetate concentration. Maximum methane yield during experiment was 291 l (kg VSadded) -1 at organic loading rate 2.0 kg VS (m3 d)-1.

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