Přeměna sluneční energie v energii elektrickou ve fotovoltaických slunečních článcích bude dle mého názoru v 21. století nejrychleji rostoucí oblastí výroby čisté energie. Podobný názor byl presentován například v čísle amerického časopisu Science [1], které bylo věnováno energii a především obnovitelným zdrojům energie. Jaké jsou hlavní argumenty pro podporu fotovoltaické přeměny sluneční energie, proč je fotovoltaika "in" (především fotovoltaické články a solární design jako nová forma architektury) a jaderná energie "out" na západ od našich hranic, jaké jsou hlavní problémy, které brzdí rozvoj fotovoltaiky, jak funguje fotovoltaický článek, co se v oblasti slunečních článků dělá v České republice a jak vypadá situace ve světě, to vše bude tématem tohoto přehledu., Milan Vaněček., and Obsahuje seznam literatury
The objective of this study was to assess genotypic variation in soybean chlorophyll (Chl) content and composition, and to test if these data could be used as a rapid screening method to predict genotypic variation in leaf tissue N content. Chl contents and composition were examined among 833 soybean (Glycine max L. Merr.) accessions and related to SPAD meter readings and leaf N content. In the initial year of the study (2002), the relationship between leaf Chl and leaf N contents (r 2 = 0.043) was not sufficiently close for Chl to be useful as a predictive tool for leaf N content. Therefore, leaf N content was not determined in 2004 but samples were again collected for determination of Chl content and composition. In 2002, the soybean accessions separated into two distinct groups according to leaf Chl a/b ratios, with the majority of a mean ratio of 3.79. However, approximately 7 % (60) of the genotypes could be readily assigned to a group with a mean Chl a/b ratio of 2.67. Chl a/b analyses in 2004 confirmed the results obtained in 2002 and of 202 genotypes, all but 6 fell into the same group as in 2002. and F. B. Fritschi, J. D. Ray.
Intense collisional transport of bimodal sediment mixture in open-channel turbulent flow with water as carrying liquid is studied. The study focusses on steep inclined flows transporting solids of spherical shape and differing in either size or mass. A process of vertical sorting (segregation) of the two different solids fractions during the transport is analyzed and modelled. A segregation model is presented which is based on the kinetic theory of granular flows and builds on the Larcher-Jenkins segregation model for dry bimodal mixtures. Main modifications of the original model are the carrying medium (water instead of air) and a presence of a non-uniform distribution of sediment across the flow depth. Testing of the modified model reveals that the model is applicable to flow inclination slopes from 20 to 30 degrees approximately, making it appropriate for debris flow conditions. Changing the slope outside the specified range leads to numerical instability of the solution. A use of the bimodal mixture model is restricted to the grain size ratio 1.4 and no restriction is found for the grain mass ratio in a realistic range applicable to natural conditions. The model reveals trends in the vertical sorting under variable conditions showing that the sorting is more intense if flow is steeper and/or the difference in size or mass is bigger between the two sediment fractions in a bimodal mixture.