Attila József Kovács

Investigation of simultaneous heat and mass transfer within the maize kernels during drying

Abstract The main goal of this study is to give a mathematical model with numerical solution to follow the heat and moisture distributions inside a cross sectional area of an individual maize kernel as a function of drying time with respect to the effects of the coupled heat and mass transfer processes. The applied drying models are similar to the modified Luikov’s equations, which were first published by Husain et al., 1973. Simultaneous heat and mass diffusion in biological materials. J. Agric. Eng. Res. 18, 343–354. This mathematical model can be used for investigating maize hybrids with different drying characteristics during drying. The data (heat physical constants and variables) for the different maize hybrids (for the slow and the fast drying individual maize hybrids) derive from experiments which have been in progress since the 1980s. The mathematical model with the boundary and initial conditions can reveal for example the difference between the fast and the slow drying hybrids. The temperature and moisture distributions inside the individual maize kernels produced by the model show more realistic picture than the results published before.

Moisture gradient vector calculation as a new method for evaluating NMR images of corn (Zea Mays L.) kernels during drying.

Magnetic resonance imaging (MRI) was used to study the moisture migration inside single corn kernel during artificial drying. MRI data were taken every half an hour during drying while the intact kernel was kept inside the magnet. The moisture distribution was not uniform inside the kernel during drying, with the fastest moisture loss being detected in the endosperm, whilst the scutellum maintained the water. Resultant gradient vectors were visualized, as a new evaluation method, from each pixel of the subtraction of segmented MRI images showing the movement of proton density inside the kernel. The data matrix containing the gradient vectors can be stored for latter use as input parameters and to check the mass transfer models.

Use of mesotrione and tembotrione herbicides for post-emergence weed control in alkaloid poppy (Papaver somniferum)

Two field experiments were carried out a year apart on the alkaloid poppy (Papaver somniferum) in 2012 and 2013 in north-west Hungary, to assess the efficacy of mesotrione and tembotrione herbicides for post-emergence weed control. Our experiments tested (1) a single application of mesotrione at 144 g active ingredient (a.i.) ha–1, (2) two separate applications of mesotrione at 144 g a.i. ha–1, (3) a single application of tembotrione at 88 g a.i. ha–1, (4) two separate applications of mesotrione at 88 g a.i. ha–1, and (5) the combination of a single application of mesotrione at 144 g a.i. ha–1 followed by a single application of tembotrione at 88 g a.i. ha–1. Both non-treated and hand-weeded plots were used as controls. Among the most important weeds, Chenopodium album was most successfully controlled in the majority of the test treatments, but Fallopia convolvulus and Polygonum aviculare tolerated each herbicide application in 2012, likely due to the dry weather conditions. Because of the botanical similarity to the crop, none of the treatments proved to be significant against Papaver rhoeas. One dosage of tembotrione alone never reduced the dry weights of the target weed species or weed numbers significantly. The cuticular wax layer of the opium poppy can provide a natural defence against these herbicides, but some temporary phytotoxic yellowish discoloration occurred after tembotrione treatments. Our results show that mesotrione in combination with tembotrione is the most effective treatment and should be employed in poppy cultivation.

Continuous field soil moisture content mapping by means of apparent electrical conductivity (ECa) measurement

Abstract A soil moisture content map is important for providing information about the distribution of moisture in a given area. Moisture content directly influences agricultural yield thus it is crucial to have accurate and reliable information about moisture distribution and content in the field. Since soil is a porous medium modified generalized Archie’s equation provides the basic formula to calculate moisture content data based on measured ECa. In this study we aimed to find a more accurate and cost effective method for measuring moisture content than manual field sampling. Locations of 25 sampling points were chosen from our research field as a reference. We assumed that soil moisture content could be calculated by measuring apparent electrical conductivity (ECa) using the Veris-3100 on-the-go soil mapping tool. Statistical analysis was carried out on the 10.791 ECa raw data in order to filter the outliers. The applied statistical method was ±1.5 interquartile (IRQ) distance approach. The visualization of soil moisture distribution within the experimental field was carried out by means of ArcGIS/ArcMAP using the inverse distance weighting interpolation method. In the investigated 25 sampling points, coefficient of determination between calculated volumetric moisture content data and measured ECa was R2 = 0.87. According to our results, volumetric moisture content can be mapped by applying ECa measurements in these particular soil types.

Emerging macroscopic pretreatment

Macroscopic pretreatment of food waste aims at the preparation of the food matrix for subsequent processing and recovery steps. The preparatory steps involve the adjustment of the phase content and properties (water, solid, fats content), the moderation of enzyme activity as well as prevention and control of any microbial growth (Galanakis, 2012; Galanakis et al., 2010a). In recent times, several emerging technologies have been researched, developed, and/or adapted from other fields for drying, sterilization, enzyme inactivation, and enhancing mass transfer in food and biomaterials. This chapter focuses on these upcoming technologies with potential applications to food waste recovery and includes foam-mat drying, electro-osmotic drying, radio-frequency drying, cold plasma technology, and high-pressure processing. The content lays emphasis on discussing the successful applications and identification of future prospects, from both a technology and an economic point of view.

Improving yield advisory models for precision agriculture with special regards to soil compaction in maize production

Evaluating the accuracy of Decision Support System for Agrotechnology Transfer (DSSAT) and ProPlanta fertilizer advisory system for maize crop (Zea mays L.) using the 2010 and 2011 database, it was concluded that simulations led to large inaccuracies in small plot sizes (0.25 ha). However the differences between simulated and measured yields related to a research field (15.3 ha) were relatively good. The 10-year databases have also been taken into consideration. The aim of the research was to adapt the different crop system models to site-specific precision technologies by taking the soil physical parameters electrical conductivity, cone index and tillage draught force into account.

Soil moisture distribution mapping in topsoil and its effect on maize yield

Abstract Soil moisture content directly influences yield. Mapping within field soil moisture content differences provides information for agricultural management practices. In this study we aimed to find a cost-effective method for mapping within field soil moisture content differences. Spatial coverage of the field sampling or TDR method is still not dense enough for site-specific soil management. Soil moisture content can be calculated by measuring the apparent soil electrical conductivity (ECa) using the Veris Soil EC-3100 on-the-go soil mapping tool. ECa is temperature dependent; therefore values collected in different circumstances were standardized to 25°C temperature (EC25). Constants for Archie’s adjusted law were calculated separately, using soil temperature data. According to our results, volumetric moisture content can be mapped by applying ECa measurements in our particular field with high spatial accuracy. Even though within-field differences occure in the raw ECa map standardization to EC25 is recommended. Soil moisture map was also compared to yield map showing correlation (R2 = 0.5947) between the two datasets.

Investigation of a Non-Thermal Effect of Microwave Treatment

The aim of our experiments was to demonstrate the non-thermal effect of microwave treatment on Saccharomyces cerevisiae fermentation activity. A method was developed for studying the effects of various treatments in the course of must fermentation. The raw material (must) was treated in different ways: (i) heat transfer; (ii) microwave treatment; (iii) inoculation with yeast, and (iv) their combinations. The results of the treatments were compared with respect to alcohol concentration, sugar content, and acidity. The results proved that sugar content of the treated samples rapidly decreased compared to the control sample, and fermentation time was 40% shorter in the fastest case. These results can be explained by the yeast inoculation and microwave treatment. Due to non-thermal effects, fermentation capacity increased by about 30%, while the energy consumption decreased.

Leaf epidermal characteristics and genetic variability in Central European populations of broad-leaved Festuca L. taxa

Leaf epidermal (micromorphological and micromorphometric) features of the leaf blade were examined with light and scanning electron microscopy in 49 Central European natural populations of species belonging to subgenera Schedonorus and Drymanthele within the genus Festuca L. In addition, molecular biological (random amplified polymorphic DNA) studies were conducted on selected populations. The goal of the study was to reveal the degree of anatomical and genetic variability at the taxon and population level, as well as to determine the most important characters that allow differentiation of the taxa in these two subgenera. The anatomical variation was compared with the genetic distance between taxa. Investigated taxa exhibited great anatomic variability in terms of both qualitative (presence or absence, shape and appearance of various cell types) and quantitative characters (frequency and size of cells). Strong correlation was found between the genetic distance of populations and the frequency and size of silica cells in the costal zone of the epidermis, which indicates that silica cells are largely determined by the genetic background, regardless of varying environmental conditions. Our studies highlight that despite the high level of variability in anatomical features and genetic polymorphism, these fescue populations clearly segregate both in terms of epidermal structure and genetic constitution.

New Simulation Technique for Particle Mixing of Stored Bulk Materials

Bulk commodities; such as cereal grains loaded into a silo require active mixing during storage. A special pulsated bottom mixer was patented at our university for gentle mixing of granular solids stored in large containers or silos. Present work intends to reveal the fundamentals in displacement of single particles mixed with different pulsation orders. A glass-walled simulator (filled with wooden cylinders) was built to enable to follow particles within the simulated mixer. Three pulsating pistons – the movements of which provide the mixing effect – were attached to the bottom of the simulator. Selected particles (some with different densities and friction coefficients) were observed during mixing and their positions were recorded after certain pulsations. Based on the measurements the mixing velocity of (particles) cylinders was calculated. The focus of examinations was to give restrictions of the mixing: density and friction of particles in connection with pulsation. However, no correlations were found between the mixing velocity and density or friction of the particles. Our basic aim was to study the effect of the two factors (particle density and friction) on the movement of particles. The gained results indicate that present models – in which these two factors are basic parameters – require revision. A mathematical model of discrete element was used to describe the movement inside the simulator, aiming to calculate the restricted parameters. The model gives similar results with the measurements. However, further investigation is required to enhance the accuracy.