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61.
Chromatographic-spectrophotometric method was used to determine the carotene content in the egg yolk of naturally raised chickens and in the eggs produced on poultry farms (industrial production) for the winter and spring periods. The aim of the study was to find out if the industrial production of eggs causes changes in the carotene content of the egg yolk. Distinct differences were recorded in the carotene content in the egg yolk of eggs obtained from private producers and of those produced on poultry farms, for both periods. Considerable differences were recorded for the spring period: the carotene content in the yolk of eggs laid in natural environment, by chickens fed natural food, was 290% higher than that in the yolk of industrially produced eggs. The difference for the winter period was 152%. 相似文献
62.
Rouaix Sandrine Laurent Cantrel Armand Yves Mattei Jean-Marie Liska Marek Galuskova Dagmar Vicena Yvan Soltesz Bela 《Chemical Engineering Research and Design》2008,86(6):633
For many years, the French “Institut de Radioprotection et de Sûreté Nucléaire” has developed studies concerning chemical effects, which can occur during a loss of coolant accident (LOCA) on a nuclear power plant, due to precipitate formation leading to an increase of head loss to sump screens. This increase can cause the loss of emergency core cooling system (ECCS) and of the containment spray system (CSS), which are the two removal heat safety systems which ensure the accident mitigation.These precipitates are formed by recombination of mineral species, which are released due to corrosion of immersed debris (particles of concrete, glass fibre insulation, piece of paint…). PHREEQC software has been used to identify nature and mass of precipitates that can be formed during a LOCA.This report presents the results of sensitivity studies carried out with PHREEQC. Chemical precipitate formation is studied as a function of several physical parameters, such as temperature, pH, nature and debris concentration. The optimal conditions in order to reduce the formation of precipitates are drawn from these calculations. 相似文献
63.
Bela Stantic Abdul Sattar Paolo Terenziani 《Journal of Intelligent Information Systems》2009,32(3):297-323
Most modern database applications involve a significant amount of time dependent data and a significant portion of this data
is now-relative. Now-relative data are a natural and meaningful part of every temporal database as well as being the focus of most queries. Previous studies
indicate that the choice of the representation of now significantly influences the efficiency of accessing bitemporal data. In this paper we propose and experimentally evaluate
a novel approach to represent now that we termed the POINT approach, in which now-relative facts are represented as points on the transaction-time and/or valid-time line. Furthermore, in the POINT approach we propose a logical query transformation that relies on the above representation and on the geometry features of
spatial access methods. Such a logical query transformation enables off-the-shelf spatial indexes to be used. We empirically
prove that the POINT approach is efficient on now-relative bitemporal data, outperforming the maximum timestamp approach that has been proven to the best approach to now-relative data
in the literature, independently of the indexing methodology (B
+ - tree vs R
*- tree) being used. Specifically, if spatial indexing is used, the POINT approach outperforms the maximum timestamp approach to the extent of factor more than 10, both in number of disk accesses
and CPU usage. 相似文献
64.
Daqing Zhang Bela I. Sandor 《Fatigue & Fracture of Engineering Materials & Structures》1990,13(5):497-509
A thermoelasticity theory for damage in anisotropic materials is developed. This theory can be applied to evaluate the damage parameter D, the normalized effective mess density ρe/ρ, and the effective modulus Ee quantitatively in some metals and composites by incorporating the thermographic stress analysis method (TSA; also, SPATE method). The effective moduli due to fatigue damage and static loads in a glass fiber/epoxy laminate obtained by the TSA method are compared with the values measured by an extensometer. The correlation between the measurements using the two methods is very good. 相似文献
65.
A numerical model has been developed based on a mass conservation level set algorithm considering a wall adhesion to predict
the surface motion for a single and double dam break problems. The simulation for the single dam break shows that the wall
adhesion force can be introduced through contact angle by modifying the level set function on the boundary in the level set
method, and the magnitude of the contact angle has an effect on the moving location of the leading front of water–gas system.
Moreover, the simulation for the double dam break presents clearly the processes of coalescence and break up of the free surface. 相似文献
66.
Bodnar Zoltan Herczku Zoltan Berces Jozsef Papp Istvan Som Ferenc Molnar Bela G. Frigyes Istvan 《International Journal of Wireless Information Networks》1999,6(2):79-91
General investigations and results from ratherextensive measurement campaigns are presented tocharacterize the propagation channel of SatellitePersonal Communication Systems; in the measurements the satellite was simulated by a helicopter andmeasurements at S band and L band were made. A newconceptual partitioning of the full link is introduced;the measrement equipment and the environment aredescribed. The major part of the paper deals withpresentation of the measurement results and theiranalyses. Measured and analyzed are average lossincluding satellite elevation and azimuth positiondependence, first-order statistics, Doppler characteristics, andwide-band characteristics. Finally, some rather generalconclusions are drawn. 相似文献
67.
Physical and chemical properties of oils are not available for most of Saskatchewan reservoirs. Hence, standard and specialized oil and water analyses were performed on fluids obtained from nineteen medium and heavy oil reservoirs. Seven of these reservoirs are producing under steam and fireflood processes.
The results of the oil analysis suggest that thermal history of the oil can be monitored by GC-MS techniques and viscosity measurements. 011 samples from different wells within a reservoir demonstrated significant differences 1n density, viscosity and other properties.
The water analysis data show that the variation in resistivity, total dissolved solids, pH and the concentration of the Ions present 1n the wellhead water samples as a function of time could be a useful Indicator for the flow pattern and flushing efficiency of steam or the advancement of the firefront and the extent of oil oxidation during thermal recovery processes. 相似文献
The results of the oil analysis suggest that thermal history of the oil can be monitored by GC-MS techniques and viscosity measurements. 011 samples from different wells within a reservoir demonstrated significant differences 1n density, viscosity and other properties.
The water analysis data show that the variation in resistivity, total dissolved solids, pH and the concentration of the Ions present 1n the wellhead water samples as a function of time could be a useful Indicator for the flow pattern and flushing efficiency of steam or the advancement of the firefront and the extent of oil oxidation during thermal recovery processes. 相似文献
68.
In this paper a method for analytic handwritten word recognition based on causal Markov random fields is described. The word
models are hmms where each state corresponds to a letter modeled by a nshp-hmm (Markov field). The word models are built dynamically. Training is operated using Baum-Welch algorithm where the parameters are reestimated on the generated word models. The segmentation is unnecessary: the system
determines itself during training the best repartition of the information within the letter models. First experiments on two
real databases of French check amount words give very encouraging results up to 86% for recognition without rejection.
Received: March 31, 2000 / Accepted: January 9, 2002 相似文献
69.
Heat-stretched fibres of bisphenol-A-polycarbonate may be produced in the fully amorphous as well as in the semi-crystalline state, depending on the choice of the molecular weight of the polymer and the spinning and stretching conditions. Investigations are made as to the influence of the stretching conditions on the orientation of the amorphous regions of the semi-crystalline material and on the orientation of the fully amorphous fibres. The orientation of the fully amorphous fibres is determined by measuring the birefringence, whereas that of the amorphous regions in semi-crystalline material results from the difference in birefringence of the entire structure of the fibres and the birefringence of the crystalline regions. The latter is calculated from the factor of orientation \documentclass{article}\pagestyle{empty}\begin{document}$ \[ \text{f}_\text{k} \text{ = }\frac{1} {2}(3\overline {\cos ^2 } \text{ }\varphi −1) \] $\end{document}, which in turn is measured by wide-angle X-ray scattering. From the polarizabilities of the individual atomic bonds it was possible, on the basis of known interatomic distances and valence angles, to calculate the components of the polarizability tensor for polycarbonate. These values were used to determine the maximum birefringence of amorphous and crystalline polycarbonate. It was shown that the calculated values for birefringence, which were obtained using orientation functions determined by X-ray scattering, agreed very well indeed with those measured from the optical birefringence. Equally good agreement for the oriented filament yarns was obtained between the values for the mean angle existing between chain direction and fibre axis as determined by X-ray examination, and the results calculated from IR-dichroism. In the case of the highly stretched polycarbonate filament yarns, it was observed that, despite the rigid molecule structure, the orientation of the crystalline regions was as high as with, for example, polyethylene-terephthalate fibres. (Mean angle between chain direction and fibre axis approx. 16°). The formation of stretch-induced crystallites with fibres of higher molecular weight polycarbonate can be explained by assuming a heterogeneous stretching mechanism with necking. In the case of low molecular weight polycarbonate fibres consolidated domains of high density cannot be destroyed by heat stretching; instead, they merely slide past each other, with the result that the stretching process takes place homogeneously without initiating any crystallization. 相似文献
70.
Boris L. Smorodin Alexander B. Mikishev Alexander A. Nepomnyashchy Bela I. Myznikova 《Microgravity science and technology》2009,21(Z1):193-198
This paper is concerned with the long-wave Marangoni instability in a horizontal liquid layer. The analysis has been carried
out for the heat flux periodically oscillating at the deformable upper interface and at the rigid lower boundary. This type
of instability is caused by the amplification of synchronous disturbances in response to the external forcing. Convection
thresholds are determined, and the critical Marangoni number is expressed as a function of frequency. It is shown that the
long-wavelength mode can give rise to the instability prior to the cellular mode within the definite range of parameters.
The long-wavelength instability can have an influence on the space-qualified manufacturing, as well as the industrial process
of thin films deposition on substrates. 相似文献