3D sound radiation reconstruction from camera measurements

In general, the measurement of the sound radiation field by machinery and partitions requires time-consuming tests, which should be carried out in specially dedicated anechoic/reverberant facilities with calibrated sensors and complex acquisition and post processing equipment. This article introduces a two-step method for the identification from optical measurements of the free-field sound radiation generated by flexural vibrations of closed shells. In the first step, the flexural vibration of the shell is reconstructed with a frequency domain triangulation technique based on short multi-view video acquisitions made with a single high-resolution, high-speed camera. In the second step, the free-field sound radiation is derived from a discretized boundary integral formulation. The study is focused on the identification of the sound radiation from the flexural vibration of a baffled cylinder model structure. The vibration and sound fields reconstructed from the camera measurements are validated against direct measurements taken with a laser scanner vibrometer and a microphone array, respectively. Overall, this research demonstrates that optical methods based on camera measurements can be suitably employed to produce fast and accurate full-field measurements of sound radiation of closed shells (without the need for a dedicated measurement environment, e.g. reverberant, anechoic chambers)

Reconstruction of cylinder flexural vibration and sound radiation fields from multi-view single-camera measurements

This paper presents experimental results on the reconstruction from video measurements taken with a single camera of the flexural vibration and sound radiation fields of a baffled cylinder. The study is focused on the vibration and sound radiation generated by a time-harmonic radial force acting on the cylinder at selected resonance frequencies. The measurement setup is composed by a single high-resolution and high-speed camera, which, however, has been set to acquire multi-views of the radiating cylinder in order to implement a frequency-domain triangulation to derive the cylinder flexural vibration field. The cylinder sound radiation field was then reconstructed with a closed form integral expression derived from the Kirchhoff-Helmholtz integral equation. More precisely, the integral expression was approximated into a summation over a grid of elements the cylinder surface had been divided into. The study shows that the proposed measurement approach accurately estimates the flexural vibration and the sound radiation fields of the cylinder at selected resonance frequencies

Reconstruction of the sound radiation field from flexural vibration measurements with multiple cameras

This paper presents the background theory and the experimental implementation of a new approach for the reconstruction of the sound radiation field produced by the flexural vibration of a distributed structure using video image acquisitions. The study is focused on tonal flexural vibration and sound radiation at the first five resonance frequencies of a baffled flat rectangular plate model-structure. The plate is divided into a regular mesh of rectangular elements whose centres are marked with small bullets. The transverse vibrations at the grid of target points are estimated via triangulation from the images acquired with six cameras unevenly spread along half of a circle located, with a small offset, parallel to the surface of the plate. The sound radiation field in free space is then reconstructed from the Rayleigh integral, which is approximated into a finite sum over the mesh of elements. Both the flexural vibration field and the sound radiation field derived from the cameras video acquisitions are contrasted with measurements taken respectively with a laser vibrometer and an array of microphones

Utilizing Ayurvedic literature for the identification of novel phytochemical inhibitors of botulinum neurotoxin A

Ethnopharmacological relevance Ayurveda, an ancient holistic system of health care practiced on the Indian subcontinent, utilizes a number of multi-plant formulations and is considered by many as a potential source for novel treatments, as well as the identification of new drugs. Our aim is to identify novel phytochemicals for the inhibition of bacterial exotoxin, botulinum neurotoxin A (BoNT/A) based on Ayurvedic literature. BoNT/A is released by Clostridium species, which when ingested, inhibits the release of acetylcholine by concentrating at the neuromuscular junction and causes flaccid paralysis, resulting in a condition termed as botulism, and may also lead to death due to respiratory arrest. Results From the docking scores and structural diversity, nine compounds including acoric acid 1, three flavonoids, three coumarins derivatives, one kava lactone were selected and screened using an in vitro HPLC-based protease assay. The bioassay results showed that several compounds possess BoNT/A LC inhibition of 50–60% when compared to positive controls NSC 84094 and CB7967495 (80–95%). Conclusion Further testing of the active compounds identified from Ayurvedic literature and structure-activity studies of acoric acid 1 using more sensitive bioassays is under way. The identification of acoric acid 1, a novel scaffold against BoNT/A, exemplifies the utility of Ayurvedic literature for the discovery of novel drug leads.https://ezproxy.stevenson.edu/login?url=https://search.ebscohost.com/login.aspx?direct=true&db=edselp&AN=S0378874116305001&site=eds-live&scope=sit