In this paper procedures for estimating the sound absorption coefficient when the specimen has inherently low absorption are discussed. Examples of this include the measurement of the absorption coefficient of pavements, closed cell foams and other barrier materials whose absorption coefficient is nevertheless required, and the measurement of sound absorption of muffler components such as perfo...

Wave propagation in coherently absorbing disordered media is generally modeled by adding a complex part to the real part of the potential. In such a case, it is already understood that the complex potential plays a duel role; it acts as an absorber as well as a reflector due to the mismatch of the phase of the real and complex parts of the potential. Although this model gives expected results f...

Reactive absorption — i.e., the absorption of gases in liquid solutions accompanied by chemical reactions — is an important industrial operation for the production of basic chemicals (e.g., sulfuric or nitric acid) and for the removal of harmful substances (e.g., H2S) from gas streams. In recent decades, this process has become especially important for the purification of gases to high purities...

The Coupled Wave Theory of Kogelnik has given a wellestablished basis for the comprehension of how light propagates inside a hologram. This theory gives an accurate approximation for the diffraction efficiency of volume phase holograms and volume absorption holograms as well. Mixed holograms (phase and absorption) have been also treated from the point of view of this theory. For instance, Guibe...

We demonstrate a novel near-field absorption spectrometer with 100 nm spatial resolution based on an ultrabroadband Ti:sapphire oscillator coupled to an aperture NSOM, enabling the measurement of nanoscale absorption spectra. The instrument is particularly suited for structural phase-selective imaging of organic materials at the nanoscale. We demonstrate that variations in the local absorption ...

We consider a phase-field model for a phase change process with phase-dependent heat absorption. This model describes the behaviour of films exposed to radiative heating, where the film can change reversibly between amorphous and crystalline states. Existence and uniqueness of solutions as well as stability are established. Moreover, a maximum principle is proved for the phase-field equation.

Grating based quantitative polychromatic x-ray phase imaging is currently a very active area of research. It has already been shown that, in such systems, the retrieved differential phase depends upon the spectral properties of the source, gratings, detector and sample. In this paper, we show that the retrieved sample absorption also depends upon the spectral properties of the gratings. Further...