Time filter

Source Type

Fenyvesi L.,Hungarian Institute of Agricultural Engineering | Fenyvesi D.,Óbuda University | Csatar A.,Hungarian Institute of Agricultural Engineering
Advances in Mechanical Engineering | Year: 2013

It is a known phenomenon that loads during fruit treatment (e.g., harvesting, transport, and manipulating) result in the damage of product parts, primarily below the surface. The maximum stress likely develops inside the fruit, which leads to its damage. This phenomenon was analysed in a general manner (general material properties, unit load) by finite element method (FEM) simulations on an apple and a pear. The shell was found to have a significant effect on the developed stress state, especially for juicy fruits. The mechanism that determines how the stress properties of tomatoes affect the stress state was analysed. According to our model, the stress maxima develop in the middle of the analysed fruits. Such stress maxima might be the reason for the inner damage, which, in the case of a missing healing period, results in fruit breakage. © 2013 L. Fenyvesi et al.


Toldi O.,Hungarian Institute of Agricultural Engineering | Tuba Z.,Szent Istvan University | Scott P.,University of Sussex
Romanian Biotechnological Letters | Year: 2010

A majority of plants possess stages in their life cycle at which specific tissues, mainly components of reproductive organs (mature pollen, seed) and dormant buds, can survive severe water loss. What is remarkable about resurrection plants is the ability of vegetative tissues (root, shoot, stem, leaves) to tolerate dehydration of the tissues and then return as functional units on rehydration. This phenomenon made resurrection plants exciting targets for molecular analysis of the poikilohydric ability and drought tolerance. Large-scale isolation of drought stress associated genes with unknown biological roles requires thorough functional analysis. Despite of the genetic and physiological complexity of desiccation tolerance, there are already examples where outcomes of targeted studies in resurrection plants are going to be directly utilized to engineer crop plants genetically. Here we show that conventional genetic transformation techniques, via in vitro plant regeneration systems, still represent an unavoidable part of the high-throughput technology chain of molecular breeding. © 2010 University of Bucharest.


Asszonyi C.,Montavid Thermodynamic Research Group | Csatar A.,Montavid Thermodynamic Research Group | Csatar A.,Hungarian Institute of Agricultural Engineering | Fulop T.,Montavid Thermodynamic Research Group | Fulop T.,Budapest University of Technology and Economics
Periodica Polytechnica: Civil Engineering | Year: 2016

Rocks are important examples for solid materials where, in various engineering situations, elastic, thermal expansion, rheological /viscoelastic and plastic phenomena each may play a remarkable role. Nonequilibrium continuum thermodynamics provides a consistent way to describe all these aspects in a unified framework. This we present here in a formulation where the kinematic quantities allow arbitrary nonzero initial (e.g., in situ) stresses and such initial configurations which – as a consequence of thermal or remanent stresses – do not satisfy the kinematic compatibility condition. The various characteristic effects accounted by the obtained theory are illustrated via experimental results where loaded solid samples undergo elastic, thermal expansion and plastic deformation and exhibit rheological behaviour. From the experimental data, the rheological coefficients are determined, and the measured temperature changes are also explained by the theory. Dedicated to the memory of Zoltán Szarka (1927-2015). © 2016, Technical University of Budapest. All rights reserved.


Petroczki K.,St Istvan University | Fenyvesi L.,Hungarian Institute of Agricultural Engineering
Computers and Electronics in Agriculture | Year: 2014

Since the construction of a static and dynamic compressive testing instrument for examining biological materials, particularly fruits and tubercular roots, the need has arisen for the construction of a computer-controlled instrument that can bridge the gap between static and dynamic investigations in this field. The main utilisation possibilities of this instrument are demonstrated some measurement results with apple. The recently developed, easy-to-use instrument presented herein is suitable for serial measurements. In its present implementation, this instrument is capable of performing compressive testing with loading sticks of typical size with constant, linear slope and cosine force-time functions in single or cyclic mode. The force is generated by a PC-controlled servo system, and the deformation is measured by a laser sensor. The excitation force is 0-15. N within 1% FS accuracy in 0-300. Hz frequency range. Deformation measuring range is 10. mm with 12. μm resolution. The system contains a PC-based data logger. © 2013 Elsevier B.V.


Keppler I.,Szent Istvan University | Hudoba Z.,Hungarian Institute of Agricultural Engineering | Oldal I.,Szent Istvan University | Csatar A.,Hungarian Institute of Agricultural Engineering | Fenyvesi L.,Hungarian Institute of Agricultural Engineering
Engineering Computations (Swansea, Wales) | Year: 2015

Purpose: The analysis of the effect of tool vibrations on the measured and simulated draught forces of cultivator tools. This paper aims to discuss this issue. Design/methodology/approach: Soil bin measurements and discrete element method (DEM)- based simulations. Findings: The soil-tool interaction induced free vibrations of cultivator tools have significant impact on the measured draught force, and the simulations made by using vibrating tools give similar results. Research limitations/implications: Accurate calibration of discrete element model parameters can be done based on the reproduction of the whole Mohr-Coulomb failure line. Draught force ratio: velocity ratio values seem to be independent of tool geometry and soil conditions in case of velocity ratio higher than 2. Practical implications: DEM-based numerical simulations can be used for modeling the effect of tool vibration on the draught force values. During discrete element simulations of soil-tool interaction, the effect of tool vibration may not be neglected. Originality/value: The paper demonstrates that during the discrete element modelling of the soil-tool interaction, the tool vibration phenomenon should not be neglected. © Emerald Group Publishing Limited.


Keppler I.,Szent Istvan University | Varga A.,Hungarian Institute of Agricultural Engineering | Szabo I.,Szent Istvan University | Katai L.,Szent Istvan University | Fenyvesi L.,Hungarian Institute of Agricultural Engineering
Engineering Computations (Swansea, Wales) | Year: 2016

Purpose - The purpose of this paper is to analyze the effect of screw angular velocity on the mixing efficiency of open mixing screws. Design/methodology/approach - Measurements and discrete element method (DEM)-based simulations. Findings - There is an optimal screw rotation angular velocity above which there is no reason to operate the mixing apparatus, as the mixing efficiency does not increase with the increase of screw angular velocity. Research limitations/implications - By using DEM-based optimization of open mixing screw apparatus, the effective mixing of agricultural grains can be achieved. The quality degradation of the dried product can be reduced. Practical implications - The causeless increase of screw angular velocity results higher power consumption and quality degradation because of the increasing value of contact forces arising between the mixed particles. Originality/value - The paper shows that by using discrete element-based simulations, the optimal working parameters of open mixing screws can be evaluated. © Emerald Group Publishing Limited.


Kocsis L.,Hungarian Institute of Agricultural Engineering | Herdovics M.,Hungarian Institute of Agricultural Engineering | Deakvari J.,Hungarian Institute of Agricultural Engineering | Fenyvesi L.,Hungarian Institute of Agricultural Engineering
Agronomy Research | Year: 2011

The drying of agricultural products is one of the most important possibilities in the whole processing line. To ensure the safe storage of the end product, drying of agricultural products is the most important. Corn drying experiments were carried out with different settings of pilot dryer to investigate the impact of drying parameters during drying. The drying process depends on several factors, such as drying temperature, air speed, and additional drying conditions. The aim of the research was to determine the behaviour of corn, the mass loss, the environmental parameters, which characterize the moisture content and temperature distribution changes during different drying conditions. The results of the experiments could help the users of an industrial dryer and manufacturers to optimize the drying process.


Keppler I.,Szent Istvan University | Kocsis L.,Hungarian Institute of Agricultural Engineering | Oldal I.,Szent Istvan University | Farkas I.,Szent Istvan University | Csatar A.,Hungarian Institute of Agricultural Engineering
Advanced Powder Technology | Year: 2012

For corn drying one of the most popular possibilities in Europe is to use a mixed flow dryer. Large differences in the vertical grain particle velocity in this type of dryers are causing differences in the residence time. Hence, uneven drying occurs causing under-drying or over-drying of grain portions. To investigate the influences of the dryer walls and the air ducts on the particle velocity distribution experiments have been carried out in industrial and laboratory sized dryers and the measurements were compared with discrete element models. The particle flow velocity distribution between the air ducts is modelled analytically based on arching hypothesis. Using discrete element models the effects of different possible constructional modifications causing more even vertical grain particle velocity distribution were analyzed. © 2011 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.


Oldal I.,Szent Istvan University | Keppler I.,Szent Istvan University | Csizmadia B.,Szent Istvan University | Fenyvesi L.,Hungarian Institute of Agricultural Engineering
Advanced Powder Technology | Year: 2012

Engineers working on the field of agriculture, food- or pharmaceutical industry or in the architecture frequently meet problems arising from the special properties of granular assemblies. Storing large amount of particulate raw materials is mostly made by using large containers, called silos. The design of such large silos is far not an easy problem. The outflow properties are one of the most important parameters of silo design. The constant discharge rate of silos differs from the discharge rate of containers filled with liquids. In case of fluids, the flowing velocity and discharge rate changes with fluid level. In case of granular materials, the velocity is constant (independent of the filling level of silo). There are methods used for the determination of silo discharge rate, but these are mostly experimental without physical explanation of the phenomenon. In this paper we demonstrate that the constant discharge rate is caused by the formation and collapse of arches in the bin. Based on this assumption, we derive an equation for determining the discharge rate. Using the same arching hypothesis we derive the equations describing the velocity distribution at silo outlets. The usability of our new approach is demonstrated by experimental investigations. © 2011 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.


Gulyas Z.,Hungarian Institute of Agricultural Engineering | Fenyvesi L.,Hungarian Institute of Agricultural Engineering | Szoboszlay S.,Szent Istvan University
Turkish Journal of Agriculture and Forestry | Year: 2012

The objectives of this research were to inspect the drop production of a twin fluid system with the Floodjet TK SS 10 042 deflector nozzle and to identify the drift of the droplets produced by the nozzle in a wind tunnel when using the nozzle with the individual settings provided by the company that enlisted our institute to do the described research task. The results of the inspection of drop production, done using a particle sizer, showed that the values of volume diameter Dv10 were low, the percentage of drops smaller than 100 μm in size was considerable, and the drop sizes varied widely in each setting. It was concluded that the risk of drift and, therefore, the risk of placing an unnecessary load on the environment existed when using the nozzle with the given settings. The application of the nozzle that was tested may cause problems in various aspects of practical spraying techniques. Based on the results of the drift measurements performed in a wind tunnel, the material deposition reported as relative coverage decreased significantly only when the recommended settings were changed at wind velocities of 2.0 m s-1 and 4.0 m s-1. At wind velocities of 4.0 m s-1 and 6.0 m s-1, detectable (>=1%) relative coverage values were recorded for each setting, even at the measurement limit. It was concluded that the inspected twin fluid system with the Floodjet TK SS 10 042 deflector nozzle does not provide the expected decrease in drift when using the given settings at wind velocities of 4.0 m s-1 and 6.0 m s-1. © TÜBITAK.

Loading Hungarian Institute of Agricultural Engineering collaborators
Loading Hungarian Institute of Agricultural Engineering collaborators