Search Results

You are looking at 1 - 10 of 10 items for

  • Author or Editor: I. Kertész x
  • All content x
Clear All Modify Search

Testing of two methods novel to ultrasonic measurements was carried out on cheese samples to estimate the Time-of-Flight (TOF) parameter. The Short Time Average/Long Time Average (STA/LTA) method and the Autoregressive Akaike Information Criterion Picker (AR-AIC picker) method are used mainly in seismology for earthquake event detection. The STA/LTA method proved to be ineffective with such noise level that is present during ultrasonic measurements, but the AIC picker algorithm yielded reliable results. A new approach for classification was tested on two types of samples, those were matching in composition, but different in treatment and texture. The method used is based on the results of wavelet decomposition, and after retrieving sufficient spectral data, a linear discriminant analysis (DA) resulted in 100% correct classification, which was compared to the DA classification results based on other methods.

Restricted access

We elaborated and tested a novel operative framework for sampling and analysing fine-scale pattern of plant composition and biomass. We combined presence/absence sampling of plant species with non-destructive biomass estimation. In an open perennial sand grassland, we used 46 m long circular transects consisting of 0. 05 m by 0. 05 m adjoining elementary sampling units. This arrangement allows us to scale across a range of 0. 05 to 20 m. For measuring aboveground green biomass, we applied digital camera sensitive to red and near infrared parts of light spectrum, and we calculated normalised differential vegetation index (NDVI). We used information statistics proposed by Juhász-Nagy to study the association between spatial patterns of production and species composition. Since information statistical functions applied require binary data, we transformed NDVI data into one or several binary variables. We found that not only dominant species but subordinate gap species were also associated to high biomass, although the strength of association varied across scales. Most of the significant associations were detected at fine scales, from 0. 05 to 0. 25 m. At the scales commensurable with quadrat sizes usually applied in grasslands, i. e., from 0. 5 to 2. 0 m, we could hardly find any significant associations between species composition and biomass. We concluded that the novel methods applied proved reliable for studying fine-scale relationships between species composition and biomass.

Restricted access

In the case of organic production the quality assessment of the fruits and vegetables is especially important. Monitoring of the maturation and ripening process, early detection of diseases, decision about harvest date and postharvest treatment need reliable, objective and – preferably – non-destructive quality testing methods. Dynamic hardness or stiffness measurement methods (resonance, impact, wave propagation) offer very useful tools in this field, but with strong limitations in applicability area and/or physical interpretation of the measured parameters. Our objective was to develop method and appropriate portable instrumentation to measure surface hardness – as quality measure – with a nondestructive method.

The computer controlled instrument has an electromagnetically excited impactor fitted with a piezoelectric acceleration sensor, a signal conditioner and A/D converter. To ensure the uniform contact behavior (contact area) between the impactor and the tested produce of wide range of shape, spherical head was applied. Conclusively, Hertz contact theory is to be applied for evaluation of the impact signal. Instead of using empirical “hardness index” – as in the case of several existing instruments – our objective was the physical interpretation of the contact phenomena. The measured acceleration signal was mathematically processed to calculate real physical parameters (force, speed, deformation), and to characterize the process similarly to the widely used texture analyzers, penetrometers. A new hardness parameter – “dynamic elastic modulus” – was introduced. According to the methodological investigations, the measurement was found to be perfectly non-destructive for a wide range of products. Conclusively, the developed method offers a useful tool for quality evaluation of organic horticultural products.

Restricted access

Abstract  

The northwestern prevailing wind direction and episodic south-to-north trajectories connect Hungarian atmosphere to the west and middle European as well as Mediterranean and Scandinavian regions that were covered by the 21 sampling sites active in an international collaboration on air quality. Our present set of data collected in Debrecen during the past decade is added to their data for comparison and the outcome is presented in this paper.

Restricted access
Nanopages
Authors: I. Tamáska, Z. Vértesy, A. Deák, P. Petrik, K. Kertész, and László Biró

Bioinspired 1+2D nanoarchitectures inspired by the quasi-ordered structures occurring in photonic nano-architectures of biological origin, like for example butterfly scales, were produced by depositing a layer of SiO2 nanospheres (156 nm and 292 nm in diameter) on Si wafers, over which a regular multilayer composed from three alternating layers of SiO2 and TiO2 was deposited by physical vapor deposition. Flat multilayers were deposited in the same run on oxidized Si (324 nm SiO2 thickness) for comparison. Different types of disorder (in plane and out of plane) were purposefully allowed in the 1+2D nanoarchitectures. The positions of the specular reflection maxima for the flat multilayer and for the two different bioinspired nanoarchitectures were found to be similar. Additionally to this, the bioinspired nanoarchitectures exhibited angle independent diffuse reflection too, which was absent in the flat multilayer. Different model calculations were made to explain the specular and diffuse optical properties of the samples. Satisfactory agreement was obtained between experimental data and model calculations.

Restricted access

We studied the long-term impact of wildfire on the vegetation dynamics of sand grasslands in a forest-steppe vegetation mosaic in Central Hungary (Kiskunság). Long-term permanent quadrat monitoring was carried out from 1997 to 2008. We sampled the forest-steppe mosaic both in burnt and unburnt areas in 100 patches altogether using 1 m × 1 m quadrats. The effect of fire and precipitation on vegetation dynamics was characterized by patch type transitions between years. Patch types were defined by means of Cocktail method. Nine patch types of sand grasslands were altogether identified. The least productive patch types, bare soil and cryptogam dominance, did not occur in the burnt patches, while annual dominated patch type appeared only in burnt patches. The frequencies of patch type changes were significantly higher in burnt patches than in unburnt ones, independently on time after fire. All the eight patch types found in the unburnt patches proved permanent, while in the burnt patches only four of seven were so. The relative frequency of patch type changes did not correlate with precipitation in the vegetation period in the unburnt patches, while positively correlated in the burnt patches. It was concluded that the long-term difference in grassland dynamics between the unburnt and burnt patches, i.e., the excess of the patch type transitions in the burnt grasslands, is due to increased drought sensitivity of the grassland, which is the consequence of the elimination of the woody component of the forest-steppe vegetation.

Restricted access

Summary  

Thirty-seven episodes of dust intrusion were observed between February 12, 1991 and August 31, 2000 in the Hungarian atmosphere and found to be of Saharan origin. They have been assigned to typical source areas in Northern Africa selected by systematic investigations related to the Mediterranean Basin. Elemental concentrations and regional signatures deduced from PIXE analysis, total suspended particle mass, and black carbon mass have been measured on dust samples collected in Debrecen, Hungary. These data combined with Aerosol Index data, and dust plume axes obtained from TOMS data from NASA satellites were used for assigning the most probable source areas of the dust transported to the sampling site. Our data and conclusions are in accordance with other published investigations on the predominant role of Saharan dust emission in building up the aerosol load of the global atmosphere.

Restricted access
Acta Alimentaria
Authors: Zs. Bodor, Cs. Benedek, T. Kaszab, J.-L. Zinia Zaukuu, I. Kertész, and Z. Kovacs

Honey is produced by honeybees from nectar, sap of plant parts, or the juicy material secreted by sucking insects living on trees. It is rich in nutritionally useful components, the occurrence of which highly depends on the botanical and geographical origin of honey. Our goal is to develop a new, rapid, and accurate combination of analytical methods for identification of botanical and geographical origin.

Physicochemical parameters (pH, electrical conductivity, moisture, and ash content), colour (L*a*b*), and antioxidant properties were determined in addition to correlative techniques, such as electronic tongue and near infrared spectroscopy. For the statistical evaluation ANOVA, principal component analysis, and linear discriminant analysis were applied.

Results showed significant differences (P<0.05) in physicochemical properties, colour, and antioxidant capacity according to the botanical origin of honeys. Electronic tongue (ET) and near infrared spectroscopy (NIR) techniques were useful in the identification of the botanical and geographical origin, showing generally good accuracy.

The physicochemical parameters are important and can serve as reference methods, completing NIR and ET as target techniques, which are promising, but need further improvement for the determination of honey origin.

Open access
Nanopages
Authors: László P. Biró, Zsolt Bálint, Zofia Vértesy, Krisztián Kertész, Géza I. Márk, Virginie Lousse, and Jean-Pol Vigneron

The complex photonic crystal type nanoarchitectures found in the wing scales of the male butterfly Cyanophrys remus were investigated structurally by electron microscopy and optically by reflectance spectroscopy. Both the vivid metallic blue of the dorsal scales and the matt, pea-green coloration of the ventral scales are attributed to photonic crystal type structures composed of chitin and air. The dorsal scales are single crystalline, while the ventral ones contain a large number of randomly oriented micron size single crystalline grains of face centered cubic inverse opal. The remarkable complexity and efficiency of biologic photonic crystals may provide clues in designing artificial structures with similar parameters.

Restricted access
Cereal Research Communications
Authors: Z. Áy, Z. Kerényi, A. Takács, M. Papp, I. Petróczi, R. Gáborjányi, D. Silhavy, J. Pauk, and Z. Kertész

The reliable monitoring of field virus infections of crop species is important for both farmers and plant breeders. The aim of this study was to detect virus infections of winter wheat in the 2006/2007 season. Twelve well-known winter wheat varieties were sown on two different dates (11 th of October and 3 rd of November 2006). Leaves of two individuals from each genotype were collected on 23rd of April 2007 to detect the virus infections ( Barley stripe mosaic virus — BSMV, Barley yellow dwarf virus — BYDV-PAV, Wheat dwarf virus — WDV and Wheat streak mosaic virus — WSMV) after an extra mild autumn- and wintertime. Virus infections were detected by enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR). The aphid-transmitted BYDV-PAV was found frequently whereas other viruses were presented very rarely or were not detected. Forty-six per cent of the tested wheat plants proved to be infected by BYDV-PAV in ELISA, while using PCR, the virus infections with BYDV-PAV was found in 58% of the samples. Further, these results suggest that the optimal sowing time is critical in the control of cereal virus diseases, and additionally, that wheat varieties respond to the virus infections differently.

Restricted access