Numerical modeling is an indispensable part of theory and design of any guided-wave photonic structure and device. It helps not only save time and money by substituting expensive and time consuming trial and error fabrication and testing by numerical simulations, but - even more importantly - it significantly contributes to proper understanding of physics involved in the operation of the structures or devices under study. In the Institute of Photonics and Electronics, this discipline has been systematically developed for more than three decades. In this communication, after a few examples of the most important achievements, we present fundamentals of the 3-D Fourier modal method recently developed and describe some results of its application to subwavelength grating waveguide structures based on silicon on insulator platform. and Numerické modelování je nepostradatelnou součástí teorie a návrhu jakékoli vlnovodné fotonické struktury a součástky. Pomáhá nejen ušetřit čas i peníze náhradou nákladné a časově náročné přípravy metodou pokusů a omylů numerickými simulacemi, ale také - a to zejména - významně přispívá k opravdovému porozumění fyzikálním jevům, na nichž je funkce těchto struktur či součástek založena. Tento obor je v Ústavu fotoniky a elektroniky AVČR systematicky rozvíjen již víc než tři desetiletí. Po několika příkladech nejvýznamnějších výsledků jsou v tomto příspěvku stručně popsány základy nedávno vyvinuté fourierovské modální metody pro modelování trojrozměrných fotonických struktur a jsou uvedeny některé výsledky její aplikace na křemíkové subvlnové mřížkové vlnovodné struktury.
Basic information about the evapotranspiration and its components is presented. System of equations describing the transport of water and energy in the soil - plant continuum is analyzed. The system of five differential equations with five unknowns is proposed, describing transport of heat and water vapour within the plant canopy, including exchange processes among the leaves and the atmosphere, vertical transport of the heat, water vapour and the energy balance. and Príspevok obsahuje základné informácie o evapotranspirácii a jej zložkách, výpare a transpirácii. Proces prenosu vody a energie v systéme pôda - porast je opísaný systémom piatich diferenciálnych rovníc kvantifikujúcich prenos vodnej pary a tepla medzi listami a atmosférou, ktoré umožnujú výpočet charakteristík vertikálneho prenosu vody a tepla v poraste a tiež bilanciu energie v tomto systéme.
Evaporation of water from the soil is described and quantified. Formation of the soil dry surface layer is quantitatively described, as a process resulting from the difference between the evaporation and upward soil water flux to the soil evaporating level. The results of evaporation analysis are generalized even for the case of water evaporation from the soil under canopy and interaction between evaporation rate and canopy transpiration is accounted for. Relationships describing evapotranspiration increase due to evaporation of the water intercepted by canopy are presented. Indirect methods of evapotranspiration estimation are discussed, based on the measured temperature profiles and of the air humidity, as well as of the net radiation and the soil heat fluxes. and Príspevok obsahuje kvantitatívny opis výparu vody z pôdy a bilanciu energie počas vyparovania, charakterizovanú rovnicou obsahujúcou turbulentný tok tepla a skupenské teplo vyparovania. Je opísaný proces tvorby suchej vrstvy na povrchu pôdy počas výparu; jeho tvorba závisí od rozdielu medzi rýchlosťou výparu a prítokom vody k horizontu výparu zo spodnej vrstvy pôdy.Výsledky analýzy možno použiť aj na kvantifikáciu výparu z pôdy pod porastom. Uvádzajú sa vzťahy na výpočet zvýšenia rýchlosti evapotranspirácie, spôsobenej intercepciou. Práca obsahuje analýzu nepriamych metód výpočtu evapotranspirácie, ktoré sú založené na meraní profilov teploty a vlhkosti vzduchu nad vyparujúcim povrchom, ako aj radiačnej bilancie a tokov tepla v pôde.
Changes in the temperature dependence of the maximum carboxylation capacity (VCmax) of Rubisco during thermal acclimation of PN remain controversial. I tested for acclimation of the temperature dependence of VCmax in quinoa, wheat, and alfalfa. Plants were grown with day/night temperatures of 12/6, 20/14, and 28/22°C. Responses of PN to substomatal CO2 (Ci) and CO2 at Rubisco (Cc) were measured at leaf temperatures of 10-30°C. VCmax was determined from the initial slope of the PNvs. Ci or Cc curve. Slopes of linear regressions of 1/VCmaxvs. 1/T [K] provided estimates the activation energy. In wheat and alfalfa the increases in activation energy with growth temperature calculated using Ci did not always occur when using Cc, indicating the importance of mesophyll conductance when estimating the activation energy. However, in quinoa, the mean activation energy approximately doubled between the lowest and highest growth temperatures, whether based on Ci or Cc., J. A. Bunce., and Obsahuje bibliografii
The thermal photoacoustic signal (279 Hz) and the chlorophyll (Chl) fluorescence of radish cotyledons (Raphanus sativus L.) were measured simultaneously. The signals were recorded during a photosynthetic induction with actinic radiation of different quantum fluence rates [20, 200, and 1200 µmol(PAR-quantum) m-2 s-1]. The rise of these signals upon irradiation saturating photosynthesis was followed in the steady state of the induction and during the subsequent dark-recovery (i.e., in dark periods of 1, 5, 15, and 45 min after the induction). From these values various parameters (e.g., quantum yield, photochemical loss, different types of quenching coefficients) were calculated. The results show that heat dissipation detected by photoacoustic measurements is neither low, constant, nor always parallel to Chl fluorescence. Therefore, the thermal signal should always be measured in order to fully understand the way leaves convert energy taken up by PAR absorption. This helps in the interpretation of photosynthesis under different natural and anthropogenic conditions (stress and damage effects).
The aim of this paper is to show the complex thermal analyses used to design of aircraft electronic control unit. Control Power Supply for Jet (CPSJ). The goal is to examine thermal conditions of power and control electronics components. With respect to aircraft application a computational fluid dynamics (CFD) method is used for heat transfer coefficient determination. This method is compared to analytic solution based on Petuchov equation of Nusselt number. The temperature conditions inside the CPSI unit are presented as results. and Obsahuje seznam literatury
The thermal resistance is one of the important behaviors of the construction and thermal insulating materials. This study describes foamed material made from fluidized bed ash (FBA) in combination with natural smectite having a filler function. The foaming effect was insured by addition of metallic aluminum to the FBA/smectite mixture. Highly calcareous FBA containing calcium oxide creates during slaking processes an alkali reaction and with aluminum develops foaming agent - hydrogen. Study of thermal resistance was a part of experiments directed on heat insulating materials and article presents test results of this life gardening material. Specific attention was focused on differences between the results of chemical analyses and the crystal phases identified by X-ray diffractions. The paper presents hypothesis of chained alumina-silicates acting as bonding agent confirmed by infra-red spectroscopy and assuring together with calcium sulfates high thermal resistance even under condition of direct flame attack., Tomáš Hanzlíček and Ivana Perná., and Obsahuje bibliografii
The relative size of the pool of electrons accumulated in stroma reductants during actinic irradiation, which can be donated to P700+ via the intersystem chain, was estimated after short-term exposure of intact Zea mays leaves to elevated temperatures. When the temperature increased from 25 to 50 °C by 5 °C steps, the relative size of the stroma electron pool went through a maximum at around 30 °C, and decreased gradually thereafter. and Ming-Xian Jin, Hualing Mi.
Thermoluminescence (TL) in green plants arises from charge recombination of charged molecules in the reaction centre (RC) of photosystem 2 (PS2) in chloroplasts. The TL technique is used for detection of alterations in the architecture of PS2 RCs. The donor side 'S-states' and the acceptor side quinone molecules (QA and QB) are involved the charge recombination processes of PS2. High temperature (70-75 °C) glow peaks are also used to detect non-photosynthetic peroxidation processes in thylakoid membranes. The TL peaks with their characteristic charge recombination can be utilised for the study of chloroplast development, ageing, chemical, biotic, and abiotic stress induced alterations in the PS2 RC and for the study of the primary photochemical events of photosynthesis. The technique has been used successfully in the characterisation of transgenic plants in the study of genetically engineered organisms. and A. N. Misra ... [et al.].
The thermoluminescence (TL) emission of photosynthesising materials originates from the recombination of charge pairs created by a previous excitation. Using a recently described TL set-up the effect of chilling stress on TL bands occurring at positive temperatures (AG, B, and HTL) was investigated in intact leaves. The far-red irradiation of leaves at low, but non-freezing temperatures induced a TL band peaking at around 40-45 °C (AG band), together with a B band peaking between 20 and 35 °C. Low temperature stress first caused a downshift and a temporary increase in the AG band after 4 h at 0 °C in the light, then a decrease in the AG and B TL bands after 1 d at 0 °C in the light. This decrease was less pronounced in cold-tolerant genotypes and in those grown at acclimating temperatures. Furthermore, an additional band appeared above 80 °C after severe cold stress. This band indicates the presence of lipid peroxides. Thus TL is a useful technique for studying the effects of low temperature stress. and T. Janda, G. Szalai, E. Páldi.