TERMIUM Plus^®

Fiche 1,  Justifications,  Anglais

Record number: 1, Textual support number: 1 CONT

Temporal Paul wavelet analysis for instantaneous phase extraction using shadow moiré technique is proposed. Unlike the Morlet wavelet, the Paul wavelet has less restriction on the adjustment of wavelet parameters and can provide an optimal time and frequency resolution for a particular application by selecting the proper parameters. The Paul wavelet is a complex wavelet and is suitable for processing the temporal intensity data obtained from the shadow moiré technique for the phase retrieval. The proposed method can extract the phase information related to the state of the dynamic object at every instant in temporal domain. The phase information is associated to the displacement, three-dimensional (3D) surface-profile and the instantaneous state of the dynamic object. In addition, the instantaneous frequency of vibrating object can be obtained using the scale of the wavelet ridge by direct integration without temporal and spatial phase unwrapping. Thus the phase unwrapping error can be avoided. An experiment is conducted on the central loaded beam to demonstrate the validity of the proposed technique.  3, fiche 1, Anglais, - shadow%20moir%C3%A9%20technique

Record number: 1, Textual support number: 1 OBS

The term “moiré” is ... a French word referring to “an irregular wavy finish usually produced on a fabric by pressing between engraved rollers” (Webster's 1981). In optics it refers to a beat pattern produced between two gratings of approximately equal spacing. It can be seen in everyday things such as the overlapping of two window screens, the rescreening of a half-tone picture, or with a striped shirt seen on television. The use of moiré for reduced sensitivity testing was introduced by Lord Rayleigh in 1874. Lord Rayleigh looked at the moiré between two identical gratings to determine their quality even though each individual grating could not be resolved under a microscope. ... Since Lord Rayleigh first noticed the phenomena of moiré fringes, moiré techniques have been used for a number of testing applications. Righi (1887) first noticed that the relative displacement of two gratings could be determined by observing the movement of the moiré fringes. The next significant advance in the use of moiré was presented by Weller and Shepherd (1948). They used moiré to measure the deformation of an object under applied stress by looking at the differences in a grating pattern before and after the applied stress. They were the first to use shadow moiré, where a grating is placed in front of a nonflat surface to determine the shape of the object behind it by using the shape of the moiré fringes.  4, fiche 1, Anglais, - shadow%20moir%C3%A9%20technique

Fiche 1,  Justifications,  Français

Record number: 1, Textual support number: 1 CONT

Le moiré d’ombre. Cette technique […] consiste à créer un moiré entre une grille de référence placée juste devant l'objet, et l'ombre de cette même grille projetée sur la surface étudiée. Les déformations de cette surface modifient le pas du réseau «ombre» créant ainsi le moiré. Une mesure du pas de ce moiré permet, à l'aide des équations précédentes, de remont3er aux déformations locales et de dresser la carte des hauteurs.  5, fiche 1, Français, - technique%20du%20moir%C3%A9%20d%27ombre

Record number: 1, Textual support number: 2 CONT

Le moiré d’ombre. Il s’agit d’un dérivé (conceptuellement, pas historiquement) de la mesure de forme par projection de frange.  6, fiche 1, Français, - technique%20du%20moir%C3%A9%20d%27ombre

Fiche 1,  Justifications,  Espagnol