Nico Felicien Declercq

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This paper gives a historical survey of the development of the inhomogeneous wave theory, and its applications, in the field of ultrasonics. The references are listed predominantly chronologically and are as good as complete. Along the historical description, several scientific features of inhomogeneous waves are described. All topics of inhomogeneous wave(More)
Ultrasonic polar scans have already proved to be well-suited as a practical means of characterizing fiber reinforced composite plates. The method consists of registering the reflected or transmitted sound amplitude as a function of each possible angle of incidence. It is hence an amplitude measurement by which it differs from more common 'time of flight'(More)
Propagation and reflection of plane elastic waves in the acousto-optic crystals tellurium dioxide, rutile, barium titanate, and mercury halides are examined in the paper. The reflection from a free and flat boundary separating the crystals and the vacuum is investigated in the (001) planes in the case of glancing acoustic incidence on the boundary. The(More)
Strong absorption of sound is often caused by the conversion of sound energy into heat. When this happens, it is not possible to study the interaction of sound with the absorbing material by means of reflected sound characteristics, because there is no reflected sound. Detecting for example the distance that sound travels in a strongly absorbing material,(More)
Zero order reflected sound from a singly corrugated interface between a solid and a liquid, insonified from the solid side by circular polarized shear waves, can become almost perfect linearly polarized in a direction parallel or perpendicular to the corrugations, depending on the frequency, and can therefore reveal the direction of the corrugations. When(More)
The anisotropic feature of most crystals, involves a direction dependent wave velocity for each of the possible modes. Paratellurite (Tellurium dioxide) is extraordinary because, for one of the propagation modes, i.e. the quasi shear horizontal (QSH) mode, the anisotropy is exceptional. This results, on the one hand in a very strong directional dependent(More)
This paper extends the theory of the diffraction of sound on 1D corrugated surfaces to 2D corrugated surfaces. Such surfaces, that are egg crate shaped, diffract incoming sound into all polar directions, which is fundamentally different from 1D corrugated surfaces. A theoretical justification is given for extending the classical grating equation to the case(More)
It is known that a handclap in front of the stairs of the great pyramid of Chichen Itza produces a chirp echo which sounds more or less like the sound of a Quetzal bird. The present work describes precise diffraction simulations and attempts to answer the critical question what physical effects cause the formation of the chirp echo. Comparison is made with(More)
This letter is a response to Strasberg's recent paper, "Comment on 'Measurement of the frequency dependence of the ultrasonic parametric threshold amplitude for a fluid-filled cavity.'" The authors dispute the conclusions of Strasberg regarding the effect observed by Teklu et al. [J. Acoust. Soc. Am. 120, 657-660 (2006)] published previously in JASA.
Bragg diffraction of x-rays occurs when the rays interact with a crystalline lattice at the appropriate angle. Bragg diffraction of visible light occurs when the light interacts at the Bragg angle with an ultrasonic field of the appropriate frequency. (The spacing between acoustic condensations and rarefactions acts like the planes in an atomic lattice.) If(More)