Earth-printshttps://www.earth-prints.orgThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Thu, 23 Mar 2023 01:29:16 GMT2023-03-23T01:29:16Z5041The set valued unified model of dispersion and attenuation for wave propagation in dielectric (and anelastic) mediahttp://hdl.handle.net/2122/1460Title: The set valued unified model of dispersion and attenuation for wave propagation in dielectric (and anelastic) media
Authors: Caputo, M.
Abstract: Since the dispersion and attenuation properties of dielectric and anelastic media, in the frequency domain, are expressed by similar formulae, as shown experimentally by Cole and Cole (1941) and Bagley and Torvik (1983, 1986) respectively, we note that the same properties may be represented in the time domain by means of an equation of the same form; this is obtained by introducing derivatives of fractional order into the system functions of the media. The Laplace Transforms (LT) of such system functions contain fractional powers of the imaginary frequency and are, therefore, multivalued functions defined in the Riemann Sheets (RS) of the function. We determine the response of the medium (dielectric o anelastic) to a generic signal summing the time domain representation due to the branches of the solutions in the RSs of the LT. It is found that, if the initial conditions are equal in all the RSs, the solution is a sum of two exponentials with complex exponents, if the initial conditions are different in some of the RSs, then a transient for each of those RSs is added to the exponentials. In all cases a monochromatic wave is split into a set of waves with the same frequency and slightly different wavelengths which interfere and disperse. As a consequence a monochromatic electromagnetic wave with frequency around 1 MHz in water has a relevant dispersion and beats generating a tunnel effect. In the atmosphere of the Earth the dispersion of a monochromatic wave with frequency around 1 GHz, like those used in tracking artificial satellites, has a negligible effect on the accuracy of the determination of the position of the satellites and the positioning of the bench marks on the Earth. We also find the split eigenfunctions of the free modes of infinite plates and shells made of dielectric and anelastic media.
Sun, 01 Nov 1998 00:00:00 GMThttp://hdl.handle.net/2122/14601998-11-01T00:00:00ZMy first fifty years in ionospheric researchhttp://hdl.handle.net/2122/1487Title: My first fifty years in ionospheric research
Authors: Dominici, P.
Abstract: The author, as an active witness, recalls what he has seen of the development of ionospheric physics during the last 50 years.
Sun, 01 Nov 1998 00:00:00 GMThttp://hdl.handle.net/2122/14871998-11-01T00:00:00ZOn baroclinic adjustment of a radiative convective atmospherehttp://hdl.handle.net/2122/1483Title: On baroclinic adjustment of a radiative convective atmosphere
Authors: Bordi, I.; Sutera, A.
Abstract: In this paper we study the implication of the hypothesis that the radiative convective equilibrium climate is neutral with respect to baroclinic eddies. If such neutral state is achieved by tropopause height readjustment, we find that the sensitivity of the climate equilibrium to baroclinic eddies is comparable to the sensitivity to water vapor profile. Multiple solutions to the readjusted tropopause are found by decreasing stratospheric static stability.
Thu, 01 Oct 1998 00:00:00 GMThttp://hdl.handle.net/2122/14831998-10-01T00:00:00ZRigorous time domain responses of polarizable media IIhttp://hdl.handle.net/2122/1442Title: Rigorous time domain responses of polarizable media II
Authors: Caputo, M.; Plastino, W.
Abstract: We present and test in detail with synthetic data a method which may be used to retrieve the parameters describing the induced polarization properties of media which fit the generally accepted frequency dependent formula of Cole and Cole (1941) (CC model). We use time domain data and rigorous formulae obtained from the exact solution of the problem found in a previous note (Caputo, 1996). The observed data considered here are the theoretical responses of the medium to box inputs of given duration in media defined with different parameters; however, as is usually done, only the discharge data are used (Patella >F2<et al.>F1<, 1987). The curve at the beginning of the discharge is studied in some detail. The method is successful in identifying the parameters when the data fit the CC model; if the medium is not exactly of the CC type the method may also help identify how the medium departs from the CC model. The Laplace Transform of the discharge for a box type input data is also given.
Sat, 01 Aug 1998 00:00:00 GMThttp://hdl.handle.net/2122/14421998-08-01T00:00:00Z