Search Results

You are looking at 1 - 10 of 67 items for

  • Author or Editor: G. Molnár x
Clear All Modify Search

Abstract  

Nuclear data for neutron activation analysis are reviewed critically. Available sources of neutron cross sections and related quantities, radioactive decay half-lives, gamma-ray energies and absolute intensities, as well as prompt gamma-ray data are assessed from the viewpoint of quantitative analysis. New developments in the production and dissemination of such data are also described, and practical recommendations are formulated. Special emphasis is given to the traceability of sources, the accuracy and age of data, and to electronic access via Internet.

Restricted access

A method is presented in this paper for solving a practical problem: how to make georeferenced mosaic of a map series using ground control points and quadratic polynomial transformation for every individual map sheet, if we expect, that after georeferencing the edges of the transformed map sheets should fit together.To solve this problem we can use a constrained polynomial fit method. In this method we use least square adjustment to get the transformation parameters for every individual map sheets, and we define constrains, that the common edges of every two neighboring map sheet should transform similarly. Solving this equation we get the transformation parameters for every single map sheet. Using these parameters for transforming the map sheets, we get georeferenced maps, that automatically fit together in a GIS software.This method has been successfully applied for georeferencing 18 map sheets of the First Topographic Survey of the Habsburg Empire. The resulting georeferenced map has larger residual errors than the individually transformed map sheets, but in exchange for we get a seamless map mosaic, that is more accurate, than the graphically merged and transformed.

Restricted access

The original map sheets of the Third Military Survey of the Austro-Hungarian Monarchy cannot be mosaicked in their original, printed form because of their uneven trapezoid format. To make a digitized raster mosaic of the individual sheets, they all should be georeferenced. Instead of the original projections, which vary from sheet to sheet, a series of sinusoid projections was defined, one unique projection for each sheet columns. The sinusoid projection provides an appropriate approximation of the original trapezoid forms and size of the sheets. Each sheet were rectified in the respective projection then reprojected to a general conic projection, defined for the final mosaic. After all of those transformations, the transformed digital content of the sheets fits to each other well enough to make a geo-referred mosaic. The location parameters of the geodetic datum used for transformation to modern projection systems are the followings: dX = +600 m; dY = +205 m; dZ = +437 m. These figures gives exact fit at the fundamental point of Hermannskogel. Because of the not unified geodetic adjustment of the original base point system, using one unified datum causes a maximum error of 220 meters throughout the whole territory of the Monarchy and the adjacent area on the maps.

Restricted access

Summary  

A beam chopper has been developed at the cold neutron PGAA facility of the Budapest Research Reactor. In the open phase of the chopper the usual prompt gamma-spectrum is recorded, while in the decay phase short-lived decay lines can be collected with good counting statistics on an extremely low baseline. A series of elements has been measured with the chopped beam technique to assess the capabilities of the new technique. An archaeological sample was also examined, to demonstrate how spectral interferences can be resolved.

Restricted access

Lake Balaton is located in the Pannonian Basin, Hungary (46°50′ N, 17°50′ E), and is characterized by its large area (594 km 2 ) and very shallow water depth (avg. 3.5 meters). The main tributary is the Zala River, which enters the western bay, and the only outlet is the Sió River in the East.Sámuel Krieger conducted the first known survey focusing on Lake Balaton in 1776. The original purpose of Sámuel Krieger’s work was to illustrate his plans of draining and canalizing Lake Balaton. This map indicates several proposed canals and bathymetric contour lines according to a water level drop of 1, 2, or 3.33 Viennese fathoms (1 Viennese fathom = 1.89 meters). The map also shows settlements, land use and relief. Krieger measured water input from tributaries, documented the water level fluctuations of the lake, and summed his results in the “Descriptio”, a document with several tables of data and a written description of Lake Balaton, the Sió River, and the possible benefits of his plan of draining the lake.Almost 90 years later, the water level was lowered by approximately 1 meter in 1863, cutting off large marsh areas from the water system of the lake. The first bathymetric map was surveyed in 1895 after the lake was partially drained. The bathymetric survey was carried out with the purpose of estimating the water volume held by the lake. Understanding water balance was important for flood control after the Sió Canal and lock was built in 1863. Water depth was measured in 2884 points, along sections near the shore, and scattered points in areas of low relief. Depth was measured with a sounding line or pole. Horizontal positions were measured optically from military triangulation points, and elevations were leveled from a network of benchmarks placed for this survey. Distances were measured in fathoms but elevations were measured in meters for better accuracy. Reprojection of the scanned map was possible, but we had to correct minor errors by triangulation. Surviving benchmarks, depicted buildings and railway bridges were used as control points. The resulting map was used to create a Digital Elevation Model of the lake floor for investigating sedimentation processes.

Restricted access

The relation between isoperimetric properties and Laplacian spectra of weighted graphs is investigated. The vertices are classified into k clusters with „few" inter-cluster edges of „small" weights (area) and „similar" cluster sizes (volumes). For k=2 the Cheeger constant represents the minimum requirement for the area/volume ratio and it is estimated from above by v?1(2-?1), where ?1 is the smallest positive eigenvalue of the weighted Laplacian. For k?2 we define the k-density of a weighted graph that is a generalization of the Cheeger constant and estimated from below by Si=1 k-1?i and from above by c2 Si=1 k-1 ?i, where 0<?1=…=Sk-1 are the smallest Laplacian eigenvalues and the constant c?1 depends on the metric classification properties of the corresponding eigenvectors. Laplacian spectra are also related to canonical correlations in a probabilistic setup.

Restricted access

Fluorescence in situ hybridization (FISH) is the most versatile and accurate molecular cytogenetic technique for determining euchromatic-heterochromatic boundaries and the locations of repetitive and single-copy DNA sequences and of chromosome-specific BAC clones on chromosomes. The combination of cytogenetic and genetic methods yields a highresolution physical map. FISH allows direct mapping of specific DNA sequences inside the cell (interphase nuclei), along meiotic pachytene chromosomes and isolated chromatin (DNA fibres). The increased sensitivity of the technique and its ability to detect gene locations provide a powerful research tool for genetic and pre-breeding studies. FISH-based physical mapping plays an important role and is increasingly used for studies at the cytological level on the chromatin organization that controls gene expression and regulation. The present minireview describes some of the benefits of alternative FISH-based techniques and their application for studying plant chromosomes and genomes.

Restricted access
Authors: G. Timár, G. Molnár and B. Veverka
Restricted access
Authors: Zs. Révay, T. Belgya and G. L. Molnár

Summary  

Hypermet-PC has been developed in the mid-nineties at the Institute of Isotopes and Surface Chemistry based on a successful FORTRAN code from the seventies. With additional calibration routines and other helping features it has proved to be a very useful tool in quantitative analysis performed either with NAA or with PGAA. The sophisticated built-in peak-shape function allows the fitting of asymmetric peaks from large-volume germanium detectors over a very wide energy range needed for PGAA. The experience collected when evaluating several thousands gamma-spectra acquired for routine analysis and spectroscopic research, is summarized in the paper.

Restricted access

Summary  

A complete series of measurements have been performed in the thermal neutron beam at the Budapest Research Reactor to determine the prompt k 0 factors for every stable element. After the installation of the cold neutron source, the flux of the beam increased by more than an order of magnitude, which made possible to determine the k 0 and cross-section values having low cross-sections with a better accuracy. The paper presents the new data for the first set of low-cross-section elements and they are compared to the best literature data.

Restricted access