Continuous ultrasonic welding of plastic films, fabrics, and even thermoplastic composite prepreg tape is a common industrial practice. However, continuous ultrasonic welding of stiff thermoplastic composite plates is challenging due to squeeze flow of resin at the welding interface, and significant local deformation of the welding stack, that are generally needed to achieve strong welds. This paper presents a novel approach to continuous ultrasonic welding of thermoplastic composite plates based on zero-flow welding. The proposed technique can create strong welds before any squeeze flow takes place at the interface. It is enabled by the use of very thin flat energy directors, owing to simultaneous melting of both energy director and adherends' matrix. The results prove the feasibility and indicate the potential for high-strength welds between thermoplastic composite plates at very high speed.

We investigated electrodermal activity (EDA) in 130 participants undergoing a shortened version of a novel easy, effective and controlled method to induce stress (the Sing-a-Song Stress Test). We compared skin conductance level (SCL), amplitude and number of skin conductance response peaks with respect to their sensitivity to the known stressor, for different scenarios of interests. EDA increased after stressor-onset for almost all participants. At a group level, the three variables were about equally sensitive. When examining the increase following the stressor with respect to preceding EDA within one individual, peak amplitude was most sensitive. Peak measures were clearly most sensitive in a simulated between-subject scenario (i.e., testing the difference in EDA between stress and non-stress intervals as if data originated from different, stressed and non-stressed groups of individuals). Peaks can be extracted by continuous decomposition (CDA) or through-to-peak analysis (TTP). In all analyses performed, CDA outperformed TTP. We thus recommend CDA peak amplitude for monitoring physiological stress effects in e.g. symbiotic systems.

In relation to the computation of electromagnetic scattering in layered media by the Gabor-frame-based spatial spectral Maxwell solver, we present two methods to compute the Gabor coefficients of the transverse cross section of three-dimensional scattering objects with high accuracy and efficiency. The first method employs the analytically obtained two-dimensional Fourier transform of the cross section of a scattering object, which we describe by two-dimensional characteristic functions, in combination with the traditional discrete Gabor transform method for computing the Gabor coefficients. The second method concerns the expansion of the so-called dual window function to compute the Gabor coefficients by employing the divergence theorem. Both methods utilize (semi)-analytical approaches to overcome the heavy oversampling requirement of the traditional discrete Gabor transform method in the case of discontinuous functions. Numerical results show significant improvement in terms of accuracy and computation time for these two methods against the traditional discrete Gabor transform method.

No abstract

No abstract