Search Results

You are looking at 1 - 10 of 19 items for

  • Author or Editor: L. Bányai x
  • Refine by Access: All Content x
Clear All Modify Search

The exact least squares line fit with errors in both coordinates (Reed 1992) is investigated together with the approximate solution based on the formalism of the linear Gauss-Helmert model or the unified adjustment approach of the classical textbook by Mikhail (1976). The similarities and the differences are described in details. In spite of the small differences the exact solution is preferable and the calculations are simpler.This paper does not deal with the errors-in-variables (EIV) models solved by the total least squares (TLS) principle, since the exact line fit solution is used to validate this general approach, which is basically designed to solve more sophisticated nonlinear tasks.In the most general case the fit of Person’s data with York’s weights is iteratively solved starting with the arbitrary zero initial value of the slope. The test computation with different but systematically chosen weights proved that in special cases — e.g. the weighted least squares sum of the distances between the data points and the estimated line is minimised — there is no need for iterations at all.It is shown that methods described by Detrekői (1991) and Závoti (2012) are special cases of the general exact solutions.Reed (1992) derived the variances of the slope and intercept parameters without their covariance. The simple linear estimation of variance-covariance matrix of the exact solution is also demonstrated. The importance of the stochastic models coupled with exact solution is also demonstrated.

Restricted access

The theoretical and practical background of the similarity transformation together with the simultaneous estimation of local geoid undulations is presented.The mean features of the traditional network adjustment on the local ellipsoids are summarized and the different Hungarian networks and known geoid solutions are shortly described as the basic data of the test computations.The eigenvalue and eigenvector decomposition revealed that the seven parameter similarity transformation cannot be applied together with the simultaneous local geoid estimation because the rotations about the X and Y axes significantly destroy the condition of the normal equations.However, the replacement of the rotations about the X, Y and Z axes by the rotation about the ellipsoidal normal of the datum point can provide a very well conditioned solution, which takes into account the special role of the datum point of the astro-geodetic network adjustment.Based on the unit weights of the input data an optimal adjustment strategy is demonstrated from a computational point of view, where the five transformation parameters can be estimated together with a very large number of local geoid undulations. The geoid has to be known in the global reference system. The geoid unknowns describe only the relative position of this known geoid with respect to the local reference system.The application of the available and the simultaneously estimated local geoid solutions proved that neglecting local geoid heights has a most significant impact on the scale parameter, while it has no significant effects on the horizontal residuals from the statistical point of view.The small scale difference (1 ppm) and the small rotation (-0.5 arc sec) about the datum point and its ellipsoidal normal of the Hungarian local system with respect to the global GPS system demonstrate the high quality of the traditional measurements as well.

Restricted access

The assessment of the results achieved in our division at the field of physical geodesy is summarised. The studies at the fields of Earth rotation, Earth tides, Earth gravity and the global and regional Earth deformations related to geodesy and geodynamics are presented by citation of the most important publications and dissertations, which cover the history of our institute. The paper ends with the case study related to the newly developed full roving GPS observation strategy.

Restricted access

B. Hofmann-Wellenhof, K. Legat, M. Wieser: Navigation. Principles of Positioning and Guidance. Springer-Verlag, Wien, New York, 2003, 427 pages, 99 figs; W. Schröder ed.: Zur Entstehung der solar-terrestrischen Physik/Some aspects of the earlier history of solar-terrestrial physics. Beitrage zur Geschichte der Geophysik und kosmischen Physik, Vol. 5, No. 3., Science Edition, 2004, pp. 150

Restricted access

In anticipation of a future vaccination program against rotavirus disease, a longitudinal survey has been set up to evaluate the epidemiologic features of rotavirus infections. In this report hospitalisation data and serotyping results are compiled from an epidemiologic survey conducted in Baranya County, Hungary. It was found that rotavirus-associated hospitalisation constituted a major part of infectious gastroenteritis cases (range, 14.9% to 28.5%). A higher proportion of rotavirus-positive cases was recorded when the serotype of predominant strains changed from G1 (1996-1999) to G4 (1999-2000), however, due to the short time period it was not possible to demonstrate a firm association between serotype prevalence and rotavirus-associated hospitalisation rate. In the future, such studies might help to understand if serotype-specific immunity against rotavirus infection plays an important role at the population level and if (re-)emerging rotavirus strains make an impact on the annual disease burden.

Restricted access

It is thought that the prefrontal cortex (PFC) subserves cognitive control processes by coordinating the flow of information in the cerebral cortex. In the network of cortical areas the central position of the PFC makes difficult to dissociate processing and the cognitive function mapped to this region, especially when using whole brain imaging techniques, which can detect frequently activated regions. Accordingly, the present study showed particularly high rate of increase of published studies citing the PFC and imaging as compared to other fields of the neurosciences on the PubMed. Network measures used to characterize the role of the areas in signal flow indicated specialization of the different regions of the PFC in cortical processing. Notably, areas of the dorsolateral PFC and the anterior cingulate cortex, which received the highest number of citations, were identified as global convergence points in the network. These prefrontal regions also had central position in the dominant cluster consisted exclusively by the associational areas of the cortex. We also present findings relevant to models suggesting that control processes of the PFC are depended on serial processing, which results in bottleneck effects. The findings suggest that PFC is best understood via its role in cortical information processing.

Restricted access

Genebanks are storage facilities designed to maintain the plant genetic resources of crop varieties (and their wild relatives) and to ensure that they are made available and distributed for use by plant breeders, researchers and farmers. The Martonvásár Cereal Genebank (MV-CGB) collection evolved from the working collections of local breeders and consists predominantly of local and regional materials. Established in 1992 by the Agricultural Research Institute of the Hungarian Academy of Sciences (Bedő, 2009), MVCGB with its over 10,000 accessions of the major species (Triticum, Aegilops, Agropyron, Elymus, Thinopyrum, Pseudoroegneria, Secale, Hordeum, Avena, Zea mays), became one of the approx. 80 cereal germplasm collections that exist globally. In Martonvásár breeding is underway on a number of cereal species, and large numbers of genotypes are tested each year in the field and under laboratory conditions. The increasing size of the research programmes assisted by a modern genebank background involve an enormous increase in the quantity of data that must be handled during research activities such as traditional breeding, pre-breeding and organic breeding. A computerized system is of primary importance to synchronize breeding and genebank activities, to monitor the quality and quantity of seed accessions in cold storage, to assist the registration of samples, and to facilitate characterization, regeneration and germplasm distribution.

Restricted access

In the past decades many papers were published on the nutritional effect and bioactive components of edible mushrooms. The fungi are able to accumulate secondary metabolites, for example, phenolic compounds, polyketides, terpenes and steroids. In case of mushrooms the button mushrooms are preferred in the Eastern-European region. Therefore white and cream type button mushroom (Agaricus bisporus) and different A. subrufescens (syn. A. blazei) cultivars were cropped, total phenolic content and antioxidant capacity (FRAP) were measured in two years of experiments. To develop the description method of mushroom products, software-supported profile analysis was applied to characterize them. The aim of the research was to compare the sensory profiles of the samples, and to find those characteristics, they actually differ in.

Restricted access

Vitamins form a heterogeneous chemical group having different stability. In foodstuffs some of them might be bound to matrix components. In the case of vitamin supplemented food products, since the vitamins are not strongly embedded in the matrix a general extraction method could be fit for purpose. The aim of this study was the simultaneous determination of the most common water-soluble vitamins, i.e. ascorbic acid (C), riboflavin (B 2 ), niacin (B 3 ), pyridoxine (B 6 ), folic acid (B 9 ) in enriched food products. Sample preparation based on the European Standard (CEN, 2003) was optimised for further LC-MS compatible chromatography. The separation of the vitamins was achieved by reversed-phase liquid chromatography. Detection was carried out with a photodiode array detector at four different wavelengths. The chromatographic method and the sample preparation were successfully applied for vitamin-enriched cereal, instant cacao powder and fruit juice samples.

Restricted access

Abstract

Elderberry pomace, a by-product generated by elderberry processing industries, may be a favourable resource for further utilisation due to its components of high nutritional quality. In our research, elderberry pomace extract (EP) was added to apple juice as natural food additive for controlling microbial spoilage and enriching antioxidant components.

During the 8-week storage period of enriched apple juice (EPA) and control apple juice samples antioxidant properties were evaluated using the FRAP assay, Folin–Ciocalteu method, and pH differentiation method. The amount of polyphenols components was quantified using an RP-HPLC method. The microbiological status of samples was studied by determining the total viable and yeast/mould counts. The EPA is an important source of polyphenol components and other bioactive compounds, and the results suggest that extract of elderberry pomace could be a promising natural preservative to improve microbiological stability during refrigerated storage and increase the quality of apple juice.

Open access