Dideriksenmacdonald3806

Metal-catalysed C-Het (P oker, To, Utes, In) as well as C-C bond arylation.

Static pressure tubes are widely used to measure the static pressure in turbulent flows. Existing work focuses on the alteration of the static pressure tubes to the flow field. This paper investigates the effects of the geometric properties of a static pressure tube on the frequency response. A theoretical formulation is developed to describe the relationship between the sound pressure inside and outside the tube. The numerical simulation results show that the peaks in the frequency response move to lower frequencies when the tube diameter, tube length, and orifice depth increase and when the orifice diameter decreases. Experiments with a 3D-printed static pressure tube were conducted to verify the analytical results. selleck compound The proposed model can be used to optimize the static pressure tube in the design stage or to correct the measurement results afterwards instead of cumbersome experimental calibration.In this article, a sonic scattering problem of arbitrarily shaped, time-varying rigid surfaces is analytically solved by exploiting perturbation theory. The results demonstrate multi-frequency scattering characteristics resulting from a single moving object and the nonreciprocity from spinning components. The proposed approach is numerically verified, from audio through to ultrasonic frequencies, by full-wave simulation based on the finite-element method. This numerical simulation also validates the non-reciprocal phenomenon in such systems. In addition, the theory for multiple Floquet scattering of sound is built, which lays the foundation for advanced studies relevant to Floquet phononic crystals and novel time-varying sonic devices.Plate-type acoustic metamaterials (PAM) consist of a thin film with multiple periodically attached masses. selleck compound Although these metamaterials can be very lightweight and thin, the resulting sound transmission loss at low frequencies can be much larger than the corresponding mass-law. This is a result of anti-resonances at which the sound transmission through the PAM is strongly reduced. One general challenge, however, is that the anti-resonances are only very narrowband. This makes the application of PAM to noise control problems with broadband noise sources or changing tonal sources difficult. In this contribution, different design strategies to improve the bandwidth of PAM for low-frequency noise control applications (multiple masses per unit cell or stacking multiple PAM layers) are evaluated using optimizations. An efficient modal based model is employed to represent the PAM using their eigenfrequencies and modal masses. The model is validated using simulations and experimental measurements. The optimization results show that it is possible to significantly improve the bandwidth of PAM using the investigated design strategies. In fact, it is shown that the same bandwidths can be achieved either using multiple masses or multiple PAM layers. This allows for some flexibility in the design of suitable noise control treatments with PAM.Auditory feedback perturbations involving spectral shifts indicated a crucial contribution of auditory feedback to planning and execution of speech. However, much less is known about the contribution of auditory feedback with respect to temporal properties of speech. The current study aimed at providing insight into the representation of temporal properties of speech and the relevance of auditory feedback for speech timing. Real-time auditory feedback perturbations were applied in the temporal domain, viz., stretching and compressing of consonant-consonant-vowel (CCV) durations in onset + nucleus vs vowel-consonant-consonant (VCC) durations in nucleus + coda. Since CCV forms a gesturally more cohesive and stable structure than VCC, greater articulatory adjustments to nucleus + coda (VCC) perturbation were expected. The results show that speakers compensate for focal temporal feedback alterations. Responses to VCC perturbation were greater than to CCV perturbation, suggesting less deformability of onsets when confronted with temporally perturbed auditory feedback. Further, responses to CCV perturbation rather reflected within-trial reactive compensation, whereas VCC compensation was more pronounced and indicative of adaptive behavior. Accordingly, planning and execution of temporal properties of speech are indeed guided by auditory feedback, but the precise nature of the reaction to perturbations is linked to the structural position in the syllable and the associated feedforward timing strategies.Cough is a common symptom presenting in asthmatic children. In this investigation, an audio-based classification model is presented that can differentiate between healthy and asthmatic children, based on the combination of cough and vocalised /ɑ/ sounds. A Gaussian mixture model using mel-frequency cepstral coefficients and constant-Q cepstral coefficients was trained. When comparing the predicted labels with the clinician's diagnosis, this cough sound model reaches an overall accuracy of 95.3%. The vocalised /ɑ/ model reaches an accuracy of 72.2%, which is still significant because the dataset contains only 333 /ɑ/ sounds versus 2029 cough sounds.This article presents an experimental and numerical parametric study of the acoustical properties of monodisperse open-cell solid foam. Solid foam samples are produced with very good control of both the pore size (from 0.2 to 1.0 mm) and the solid volume fraction (from 6% to 35%). Acoustical measurements are performed by the three-microphone impedance tube method. From these measurements, the visco-thermal parameters-namely, viscous permeability, tortuosity, viscous characteristic length, thermal permeability, and thermal characteristic length-are determined for an extensive number of foam samples. By combining Surface Evolver and finite-element method calculations, the visco-thermal parameters of body centered cubic (bcc) foam numerical samples are also calculated on the whole range of solid volume fraction (from 0.5% to 32%), compared to measured values and to theoretical model predictions [Langlois et al. (2019). Phys. Rev. E 100(1), 013115]. Numerical results are then used to find approximate formulas of visco-thermal parameters.