Passage Of Acoustic Waves Research Articles

Ultrasound-Assisted Extraction of Natural Pigments From Food Processing By-Products: A Review.

Ultrasound is an emerging technology, which has been highly explored in the food area to improve processes and products. When ultrasound is applied to a product with solid or fluid characteristics, the passage of acoustic waves and acoustic cavitation generates different mechanisms responsible for modifications in the original matrix of the sample. These effects of ultrasound can also be used to take advantage of by-products, for example by extracting compounds of interest, including natural pigments. Natural pigments or colorants are being highly demanded by different industries not only for color purposes but also due to their healthy properties, the greater demands in regulations and new consumer preferences. This review presents an updated critical analysis of the application of ultrasound-assisted extraction (UAE) to obtain natural pigments from food processing by-products. Initially, the ultrasound effects and mechanisms that improve the extraction of natural pigments in a fluid medium, as well as the factors that influence the extraction and the energy consumption of UAE are analyzed and described. Subsequently, the UAE application to obtain pigments belonging to the groups of carotenoids, chlorophyll, anthocyanins and betalains is evaluated. These sections detail the processing conditions, positive and negative effects, as well as possible applications of the extracted pigments. This review presents relevant information that may be useful to expand and explore new applications of ultrasound technology as well as promote the revaluation of by-products to obtain pigments that can be used in food, pharmaceutical or cosmetic industries.

To the question of the vibroacoustic methodology for the development of carbon plastics’ diagnostics

This article describes in detail the process of creating panels from a composite material by the method of vacuum infusion with various types of defects pre-installed in them. The most common types of defects that can arise in parts made of composite materials as a result of a violation of the technological process, the presence of defects in the original material, in particular, reinforcing fabric, as well as defects associated with the low qualification of the master are considered. The creation of such prototypes is necessary for the development of quality control methods for products made of composite materials. A vibroacoustic diagnostic method based on the passage of acoustic waves through a composite product is considered. It is shown that it is possible to estimate the size of a defect and the depth of its occurrence in a composite material by changing the intrinsic frequency characteristics of the wave field. Experimental data on diagnosing panels with defects is presented.

Earth Motion Caused by Local Atmospheric Pressure Changes

Summary Observations have been made of the local atmospheric pressure field and the long-period seismic noise fields both on the surface of the Earth and in a mine at a depth of 183 metres. The observations show that during windy intervals and in the period range 20–100 s there is a strong correlation between local atmospheric pressure changes and the noise recorded by a vertical seismograph located on the surface. In contrast, over the same range of periods there is no correlation between the seismic noise recorded in the mine and local atmospheric pressure changes except during the passage of acoustic waves. It is shown that the noise in this pass band is not due to the buoyant response of the seismograph, but is caused by the motion of the Earth responding to atmospheric pressure changes.

Field trials of a seismoelectric method for detecting massive sulfides

An underground test of a seismoelectric prospecting method for massive sulfides was performed at the Mobrun Mine (Rouyn‐Noranda, Quebec) in June 1991. The method is based upon the conversion of seismic energy to high‐frequency pulses of electromagnetic radiation by sulfide minerals. The delay between shot detonation and detection of the electromagnetic radiation gives a one‐way traveltime for the acoustic wave to reach the zone of seismoelectric conversion, which when combined with P‐wave velocity allows the shot‐to‐ore zone distance to be calculated. A 0.22-kg explosive charge located within 50 m of the orebody provided the seismic excitation, and the resulting electromagnetic emissions were received by electric dipole and induction‐coil antennas. First‐arrival information from a 35‐shot survey above an orebody, the 1100 lens, provides firm evidence that short duration pulses of electromagnetic radiation are produced by the passage of acoustic waves through the orebody. The survey also demonstrated that seismoelectric conversions could be induced at shot‐to‐orebody distances of 50 m and detected at distances of up to 150 m from the orebody. Areas of seismoelectric conversion are highlighted in sections produced by plotting the position of seismic wavefronts during signal reception. The sections show anomalies that correlate with the known structure and location of the orebody and demonstrate the potential of using this seismoelectric phenomenon as an exploration tool.