We describe an experimental investigation of various methods of using the non-intrusive particle image velocimetry (PIV) technology to obtain the acceleration field of fluid flows and particularly the force being exchanged between a fluid flow and its boundaries. Methods based on the Lagrangian and the Eulerian specifications respectively have been developed, applied to experiments and compared. The experiments were performed by using a four-CCD-camera system designed to acquire between two and four frames in a fast time sequence, to provide single- or multiple-exposure PIV images of general fluid flows. The experiments involved various types of surface waves impinging upon a vertical wall at the end of a flume. Simultaneous monitoring with various transducers provided the experimental evaluation of the force predictions, whereas numerical simulations and PIV measurements have been used to validate the techniques for determining accelerations.
A novel spectrometer concept is analyzed and experimentally verified. The method relies on probing the speckle displacement due to a change in the incident wavelength. A rough surface is illuminated at an oblique angle, and the peak position of the covariance between the speckle patterns observed in the far field with the two wavelengths reveals the wavelength change. A spectral resolution of 100 Mhz is argued to be achievable.
The article offers a critique of the concept of cultural intelligence (CQ) from a semiotic perspective. It addresses three assumptions that underpin the CQ concept: that CQ exists, that conflict and misunderstandings are antithetical to CQ and that metacognition involves a cultural dimension. The analysis focuses in particular on the dimension of cultural metacognition which has recently been claimed to be the CQ concept's main contribution compared to earlier concepts such as cross-cultural or intercultural competence, a claim which is found to be overstated. The article uses the example of CQ training to illustrate the need for greater attention to context and motivation when CQ is deployed for business purposes, as well as to the role of experience in cultural learning processes. At a broader level, the article urges caution in assuming that all human attributes can be trained for business purposes, especially through short-term interventions.
We present a low-cost optical design for the detection of speckle translation, which can provide measures of in-plane translation or the rotation of a solid structure. A nonspecular target surface is illuminated with coherent light. The scattered light is propagated through an optical arrangement that has been particularly designed for the type of mechanical measurand for which the sensor is intended. The dynamics of the speckle field that arise from the target surface are projected onto a lenticular array, constituting a narrow spatial bandpass filter for the speckle spectrum. The filter provides access to the full phase information of the temporal quasi-sinusoidal intensity output; thus differential arrangements of photodetectors can provide suppression of low-frequency oscillations and higher harmonics, and the direction of the speckle translation can be determined. The spatial filter of the sensor is characterized, and the precision of the sensor when it is integrated with an electronic zero-crossing-detection processor is investigated. The best measurement accuracy obtained at constant velocity is 1% at 1.6-mm translation; the relative standard deviation decreases with the square root of the distance traveled.
We disclose a simple, optical touch screen technique based on a planar injection molded polymer waveguide, a single laser, and a small linear detector array. The solution significantly reduces the complexity and cost as compared to existing optical touch technologies. Force detection of a touching finger is also demonstrated.
The change of coherence and polarization of an electromagnetic beam modulated by a random anisotropic phase screen passing through any optical system is found within the framework of complex ABCD-matrix theory This means that the formalism can treat imaging and Fourier transform and free-space optical systems, as well as fractional Fourier transform systems, with finite-size limiting apertures of Gaussian transmission shape. Thus, the current paper shall be considered as a continuation, extension, and generalization of a previous work by Shirai and Wolf [J. Opt. Soc. Am. A21, 1907 (2004)]. It will be shown that the inclusion of apertures in the optical system strongly influences not only the propagation of spatial coherence but also the degree of polarization of a propagating field. Analytical expressions of coherence and polarization propagation will be given in terms of the matrix elements for any complex optical system.
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