Wyniki wyszukiwania - Biblioteka Nauki

Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl

Ograniczanie wyników

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: quality factor

Sortuj według:

Ogranicz wyniki do:

Modelling of multilayered dispersive and dissipative media

100%

Narayan J.

2000

tom Vol. 48, nr 3

347-358

This paper presents a frequency domain formulation in agreement with Futterman's third absorption-dispersion relationship, for synthesizing normal incident seismograms for a layered elastic and dissipative media. In the past, synthetic seismograms have been computed in time and frequency domains using attenuation and dispersion phenomena separately as well as simultaneously. The time domain modeling suffers from minimum phase formulation and inadequate treatment of dispersion. Amplitude and phase spectra have been computed using the ratio of spectra of upgoing and downgoing waves in the layers and Fast Fourier Transform (FFT) technique bas been adopted for converting the response in time domain. The results have revealed changes in the reflected wave forms in both frequency and time domains in accordance with the theory of absorption and dispersion phenomena. Results with constant quality factor depict an increase in both attenuative and dispersive effects with a decrease in the quality factor. Frequency dependent and independent quality factors were considered and almost similar responses have been obtained. The time lead caused by dispersion is found to be much smaller when the reference frequency is at the center of the desired frequency band. It has also been observed that the time lead or delay caused by dispersion increases with the travel time. Key words: synthetic seismograms, dispersive media, dissipative media, quality factor.

Helical Resonator for Measurements of Parameters of Dielectrics at 25 MHz

100%

Żukociński M. , Abramowicz A.

2009

tom Vol. 55, No 3

515-524

This paper presents a helical resonator for measurement of complex permittivity of dielectric materials in form of thin sheets at 25 MHz. The indirect method of permittivity reconstruction is investigated. The full-wave 3D electromagnetic simulator is used to analyse the structure, create experiment model and build lookup database. The results of experiments are used to verify the possibility of accurate resonant measurement method at such low frequency.

Helical resonator for measurements of dielectrics

63%

Żukociński M. , Abramowicz A.

2009

tom Vol. 50, nr 8

94-97

This paper presents a helical resonator for measurement of complex permittivity of dielectric materials in form of thin sheets at 25 MHz. The indirect method of permittivity reconstruction is investigated. The full-wave 3D electromagnetic simulator is used to analyse the structure, create experiment model and to build lookup database. The results of the experiments are used to verify the possibility of accurate resonant measurement method at such low frequency.

Opisano metodę pomiarową i realizację praktyczną układu pomiarowego w postaci rezonatora helikalnego działającego na częstotliwości 25 MHz. Opisano także sposoby określania przenikalnosci elektrycznej z analizy numerycznej struktury i pomiarów referencyjnych. Trzywymiarowy symulator elektromagnetyczny został użyty do analizy struktury i stworzenia bazy danych w postaci tabel wyników. Resultaty doświadczalne wskazują na możliwość budowy dokładnego rezonatora pomiarowego na niskich częstotliwościach.