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  • Author or Editor: J. Gál x
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Abstract  

We develop the beginning of a theory of semigroups of linear operators on p-Frchet spaces, 0 < p < 1 (which are non-locally convex F-spaces), and give some applications.

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Abstract

The first aim of our research is to calculate the solar irradiance on roofs assuming clear sky and real (climatologically typical) conditions, respectively, and compare them in a densely built inner city study area in Szeged (Hungary). The second aim is to analyse the shading effect of the tree-crowns on the possible solar energy gain of building roofs. The calculation of the climatologically potential solar energy gain based on an empirical atmospheric transmittance (calculated from the measured global radiation values). The results show that in the case of clear sky condition the urban vegetation (tree-crowns) causes significant potential solar energy loss on the roofs, but in the real situations this effect is less significant. These obtained results clearly illustrate how useful tool could be the presented calculation method at the economical and technical planning stage of the installation of solar systems on roofs.

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The study area is the peaty bed of Navad-patak mire situated in the North-Eastern Alföld, on the Bereg plain, which is slightly investigated area. The purpose of our research was to reconstruct the recent vegetation dynamic processes of the mire from 1950 till 2005. Beside the aerial photos we used the ERDAS Imagination remote sensing program, and made digital photo interpretation. We divided the vegetation history into three parts. In the first period, the nutrient load of the mire was increased, peat decaying and foresting processes started, the open peat-moss dominated associations ( Eriophoro vaginati-Sphagnetum, Carici lasiocarpae-Sphagnetum ) were disappeared. In the second period the expansion of the forest vegetation continued, the species composition transformed, and the characteristic species of the mentioned associations ( Eriophorum vaginatum, E. angustifolium, Carex lasiocarpa, Drosera rotundifolia, Sphagnum magellanicum ) were all disappeared. The third period starts with the artificial flooding in 1994. In the beginning the peat-mosses were all extinct, floating mires appeared immediately and their quick succession started and still runs. The fourth period would be start with the appearance of peat-mosses.

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Investigation of dehydration process, II

Processes preceding dehydration of alkaline earth halides

Authors: É. Buzágh-Gere, J. Sztatisz and S. Gál

The dehydration of hydrated calcium and strontium bromides and iodides was studied by thermogravimetry and differential thermal analysis. The melting in the crystallization water was distinguished from the dehydration in a self-generated atmosphere. The results of the TG and DTA curves made simultaneously were verified by measurements with a Du Pont DSC apparatus. This latter investigation was extended to the previously studied chlorides too. Correlations were found between the temperature of melting or of dehydration and the ionic radii of the respective cations and anions.

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Abstract  

Novel methods of unified evaluation of two (or more) thermogravimetric curves have been worked out on the basis of known non-linear parameter estimating procedures (Gauss-Newton-Marquardt-type regression and the direct integral method of Valkó and Vajda were adapted). Their ability to provide estimate for common kinetic parameters of several TG (m−T) or DTG (dm/dt-T) curves were tested for pairs of curves of different heating rates, and for repeated curves of the same heating rate, obtained for the decomposition of CaCO3 in open crucible. In these cases the Arrhenius terms and then-th order model functions were assumed. The fitting ability of estimations made for single curves and for pairs of curves sharing different number of parameters, was judged on the base of residual deviations (S res) and compared to the standard deviation of the measurements. In the case of different heating rates, the two curves could not be described with the assumption of three common parameters, because of the minimum residual deviation was very high. However, sharing of activation energy and preexponential term only, and applying different exponents for the two curves, provided a satisfactory fit by our methods. Whilst in the case of repeated curves, we could find such a common three-parameter set, which has a residual deviation comparable with the standard deviation of the measurements. Because of their flexibility (taking into account the variable number of common parameters and the versatile forms of model equations), these methods seem to be promising means for unified evaluation of several related thermoanalytical curves.

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Changes in the water content of aluminium sulphate hydrate were investigated gravimetrically at room temperature in air with different relative humidities. The samples conditioned in this way were characterized by thermoanalytical (TG, DTG, DSC) and X-ray diffraction measurements. Industrial aluminium sulphate hydrate obtained by freezing the melt has a partly crystalline structure. After grinding, this material crystallizes during storage. This process requires a humid atmosphere; increasing relative humidity brings about more intensive crystallization.

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The occurrence of a periosteal chondroma (juxtacortical chondroma) in an adult male Uromastyx maliensis is documented for the first time. The chondroma developed near the right shoulder joint from the periosteal membrane, causing partial atrophy in the surrounding skeletal muscles. In the chondroma tissues widespread central necrosis and secondary calcium salt deposition were observed. Monomorphic chondrocytes were irregularly spread in the chondromucin matrix. The lizard had locomotor problems due to irritation of the periosteum and reduced movement of the bones constituting the shoulder joint caused by the chondroma.

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