Total Loss Level Research Articles

FACTOR OF QUALITY FOR PASSIVE NON-TUNABLE BAND-STOP FILTERS

The notion of a quality criterion for non-tunable band-stop filters is introduced, and on the basis of it a comparison of filters with different designs is performed. The quality criterion takes into account the electrical characteristics of the filter and its dimensions, including the volume, the central frequency of the notch band, the level of total losses in the passbands, the width of the notch band by the level of total losses, the width of the notch band by attenuation level. Thus, it allows you to compare the quality of design and manufacture of passive notch filters of various types. The necessary analytical expression is presented, and for a number of variants of filter execution, the corresponding calculation results are given. The stated materials allow us to estimate and optimize the system of interrelated parameters of filters of an arbitrary physical structure.

The optical characteristics of the nonlinear optical single crystal CdSiP2 in the terahertz and infrared ranges

Experimental study of mechanisms forming absorption of Terahertz (THz) radiation in the advanced nonlinear-optical crystal CdSiP2 has been performed by backward-wave oscillator, time-domain and infrared spectroscopy. The classical oscillator model and Lyddane–Sachs–Teller relation were used to calculate the dispersion parameters of phonon modes. The spectra of complex permittivity and absorption coefficient have been determined based on the calculated dispersion parameters. The application of the Fresnel formulas for the absorption analysis in the THz region together with the results of the fit of the phonon modes made it possible to obtain quantitative data on the magnitude of the additional radiation losses in the THz range. Additional loss mechanisms give rise to increase the total absorption by at least one order of magnitude compared to the phonon contribution. The increase of the polariton absorption in the low-frequency dispersion branch is typical for crystals with ionic and ion-covalent bond and is composed of extrinsic losses and difference multi-particle processes. The level of total losses in the THz region in CdSiP2 single crystal is comparable to the values in other nonlinear-optical crystals, which makes this material promising for nonlinear-optical conversion of the infrared radiation into the THz region.

Estimation des pertes à la récolte du colza d’hiver (Brassica napus) dans des conditions variées

Oilseed rape seed loss during harvest can cause subsequent unwanted gene flow and thus give raise to management difficulties in order to keep segmented different productions. Furthermore, seed loss reduces benefits of producers. This loss was evaluated in different conditions and trials carried out in three French regions from 2002 to 2004. Seed loss was divided into three categories : before harvest, under the cutter bar and behind the combine harvester. Total loss represented on average 8,2 % of the harvest for grain water content under 12 %. But this figure does not take an important variability into account. Indeed, an advanced cutter bar could reduce loss by 80 % and grain humidity at harvest plays an important part in the total loss level and its distribution. Before harvest low grain water content could make seed loss more sensitive to climatic events. Under the cutter bar, seed loss is inversely proportional to grain water content. On the contrary, it increases with grain water content behind the combine, due to loss in green siliquae. These studies can help improving advice to producers and contribute to improve gene flow models.

Influence of a thin dielectric layer on nonreciprocal effects arising at the reflection from magneto-optic films

An additional transparent dielectric layer allows to create an antiresonant light-wave field distribution in layered structure, containing absorbing magneto-optic (MO) film. This results in nonreciprocal phase shift enhancement with simultaneous decrease of nonreciprocal losses and low level of total losses.