Ultrasonic Tank Research Articles

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Currently, overusing agro-chemicals on agricultural plants affects consumer health. The urgent issue, so, is to have a high-tech solution to remove the chemical residue in post-harvest agricultural products. Thus, designing ultrasonic washing tanks used to clean agricultural products out of chemical residues would be a research contributing to save consumer’s health from food poisoning. The tank was designed to allow adjusting transmission frequency and intensity of ultrasonic waves suitable to different agro-products and the primary experiment results indicated that using the designed ultrasonic tank is effective in reducing a kind of insecticide residue from some vegetables.

Rapid Prototyping of Pyramidal Structured Absorbers for Ultrasound

Acoustic measurements or ultrasonic testing can be strongly affected by reflections or echoes from test tank walls. In order to create a non-reflecting environment equivalent to infinite medium, a pyramidal structured absorber (PSA) can be used to coat the walls of an ultrasonic tank. In this work, we model an array of tetragonal pyramid ultrasonic wave absorbers. This model is based on two coupled first-order equations describing the stress and particle velocity within an isotropic medium. For absorbing media, the Kelvin-Voigt model of viscoelasticity is used. The equations are discretized in 2D using an efficient time-stepping pseudo-spectral scheme that takes in consideration both, the acoustic properties and attenuation characteristics of the composite materials. We then built a 3D printed PSA using a Stratasys Objet500 Connex 3D printer, which allows to combine photopolymers in specific concentrations and microstructures. We designed PSA covering the frequency ranges from 0.5 MHz to 5 MHz and from 1 MHz to 10 MHz, with double homogeneous layer: a core of rubber material with a skin of a variety of elastomers by combining rigid and flexible materials. Each single pyramid contains two major parts: the ground of the pyramid (9.4 mm base × 4.7 mm height, for 0.5 MHz and 4.7 mm base × 2.35 mm height, for 1 MHz) and the body of the pyramid (23.5 mm height, for 0.5 MHZ and 11.75 mm height, for 1 MHz). The measured echo-reduction was greater than 35 dB at the covering frequency range and the transmission loss was estimated by 20 dB. Echoes increase rapidly for frequencies below the minimum frequency of the covering range. The modeling and 3D printing of PSA with different sizes, in a wide range of frequencies, is a cost-effective custom solution for a wide range of applications including for example, radiation force balances, hydrophone mounts and medical ultrasound equipment.

Achieving surface chemical and morphologic alterations on tantalum by plasma electrolytic oxidation.

BackgroundSearch for materials that may either replace titanium dental implants or constitute an alternative as a new dental implant material has been widely studied. As well, the search for optimum biocompatible metal surfaces remains crucial. So, the aim of this work is to develop an oxidized surface layer on tantalum using plasma electrolytic oxidation (PEO) similar to those existing on oral implants been marketed today.MethodsCleaned tantalum samples were divided into group 1 (control) and groups 2, 3, and 4 (treated by PEO for 1, 3, and 5 min, respectively). An electrolytic solution diluted in 1-L deionized water was used for the anodizing process. Then, samples were washed with anhydrous ethyl alcohol and dried in the open air. For complete anodic treatment disposal, the samples were immersed in acetone altogether, taken to the ultrasonic tank for 10 min, washed again in distilled water, and finally air-dried. For the scanning electron microscopy (SEM) analysis, all samples were previously coated with gold; the salt deposition analysis was conducted with an energy-dispersive X-ray spectroscopy (EDS) system integrated with the SEM unit.ResultsSEM images confirmed the changes on tantalum strips surface according to different exposure times while EDS analysis confirmed increased salt deposition as exposure time to the anodizing process also increased.ConclusionsPEO was able to produce both surface alteration and salt deposition on tantalum strips similar to those existing on oral implants been marketed today.

Alpha-glucosidase Inhibition Activity of Methanol Extracts Obtained from Three Dryopteris Species and Fractions Obtained from D. nipponensis

This study was performed to analyze the α-glucosidase inhibitory activity in fronds of 3 Dryopteris species, D. crassirhizoma, D. nipponensis and D. fragrans var. remotiuscula, and in rhizomes of D. crassirhizoma and D. nipponensis, and then to explore the natural materials for developing natural α-glucosidase inhibitors. An analysis was performed using the crude extract of fronds and rhizomes obtained through 30 minutes ultra sonification extraction in 42 kHz ultrasonic water tank with 100% methanol, as a solvent, after the freeze drying and grinding. As a result of the analysis of α-glucosidase inhibitory activity, in respect of IC50 values of fronds and rhizomes, D. nipponensis was the highest as 4.13 and 2.19µg·mL-1 respectively among 3 Dryopteris species and their inhibitory activities were 342 and 646 times higher than acarbose(IC50=1413.70µg·mL-1) used as control group, respectively. In respect of the biomass required to inhibit 50% of α-glucosidase activity, the fronds and rhizomes of D. nipponensis required the least as 0.04 and 0.05mg, respectively. From the crude extract, D. nipponensis with high α-glucosidase activity and less required biomass was selected. And then the crude extract was subdivided by the solution in the order of n-hexane, chloroform, ethyl acetate, n-butanol and water in order to analyze α-glucosidase inhibitory activity as well as the biomass required for each fraction comparatively. The fronds of D. nipponensis was high in n-butanol fraction(1.09µg·mL-1), and the rhizome was high in water fraction(9.36µg·mL-1), indicating the inhibitory activity 1297 and 151 times higher than acarbose, respectively. The required biomass of the fronds and rhizomes of D. nipponensis were highest in n-butanol and water fraction. As a result of this study, the crude extract of D. nipponensis showed high α-glucosidase inhibitory activity requiring a small amount of biomass. Thus, its value for the development to antidiabetic agent is considered very high. Keywords: Dryopteris nipponensis, Fresh material, n-Butanol, n-Hexane, Whole extract

Design and testing of an underwater acoustic Fresnel zone plate diffractive lens

Fresnel zone plate (FZP) lenses offer a means of focusing sound based on diffraction in cases where the thickness of conventional lenses may be impractical. A binary-profile FZP for underwater use featuring a center acoustically opaque disk with alternating transparent and opaque annular regions was fabricated to operate nominally at 200 kHz. The overall diameter of the lens was 13 in. and consisted of 13 opaque annuli. The opaque regions were 3 mm thick and made from silicone rubber with a high concentration of gas voids. These regions were bonded to an acoustically transparent silicone rubber substrate film that was 1 mm thick. The FZP was situated in a frame and tested in a 5 x 4 x 4 cu. ft. ultrasonic tank using a piston source for insonification. The measured focal distance for normal incidence of 12.5 cm agreed with finite-element predictions taking into account the wavefront curvature of the incident field which had to be included given the finite dimensions of tank. The focal gain was measured to be 20 dB. The radius to the first null at the focal plane was approximately 4 mm, which agreed with theoretical resolution predictions. [Work sponsored by the Office of Naval Research.]

Effects of an Injection Angle of Water Pipes in an Ultrasonic Cleaning Tank on Particle Disposal Capability

This paper presents simulation of particle dispersion in an ultrasonic cleaning tank.Contaminants removed from work-pieces by means of ultrasonic waves need to be disposed from the tank during the cleaning process. This is achieved by using water injection from horizontal tubes placed at the bottom inside the tank. It is expected that injection angles could affect the performance of particle disposal. The two-phase flow simulation is adopted to predict disposal capability while the computational fluid dynamic is carried out by means of finite volume analysis. Simulation results of particle dispersion in the tank with various injection angles are conducted, displayed, and concluded.

자생 양치식물 9종의 성엽 및 근경 추출물의 α-glucosidase 억제 활성

본 연구는 자생 양치식물 9종의 성엽과 근경을 재료로 <TEX>${\alpha}$</TEX>-glucosidase 억제활성을 분석하여 천연 <TEX>${\alpha}$</TEX>-glucosidase 저해제로서 개발 가능한 식물 소재를 선발하기 위하여 수행하였다. 수확된 성엽과 근경은 수세 후 동결건조 하였으며, 건조시료를 분쇄하여 100% 메탄올 용매로 30분 동안 초음파 추출을 하였고, 추출 후 감압여과 하여 <TEX>${\alpha}$</TEX>-glucosidase 억제활성을 측정하였다. 양성 대조구로는 acarbose를 사용하였다. 추출물 <TEX>$50{\mu}L$</TEX>에 0.7 unit <TEX>${\alpha}$</TEX>-glucosidase 효소액 <TEX>$100{\mu}L$</TEX>를 넣고 혼합하여 <TEX>$37^{\circ}C$</TEX>에서 10분간 반응시킨 후, 1.5 mM <TEX>${\rho}$</TEX>-NPG 기질용액을 <TEX>$50{\mu}L$</TEX> 넣고 <TEX>$37^{\circ}C$</TEX>에서 20분간 반응시켰다. 1 M <TEX>$Na_2CO_3$</TEX> 1 mL로 반응을 정지시키고 405 nm에서 흡광도를 측정하였다. 회귀분석을 이용하여 0.7 unit <TEX>${\alpha}$</TEX>-glucosidase 용액의 활성을 50%를 억제하는데 필요한 시료의 농도(<TEX>$IC_{50}$</TEX> 값)를 구하였다. 양치식물 9종의 <TEX>${\alpha}$</TEX>-glucosidase 억제활성은 성엽(<TEX>$IC_{50}=14.00{\sim}913.33{\mu}g{\cdot}mL^{-1}$</TEX>)과 근경 추출물(<TEX>$IC_{50}=12.93{\sim}205.84{\mu}g{\cdot}mL^{-1}$</TEX>)에서 공히 acarbose(<TEX>$IC_{50}=1413.70{\mu}g{\cdot}mL^{-1}$</TEX>)에 비해 높았다. 양치식물의 추출물은 acarbose에 비해 성엽은 1.55~100.98배, 근경은 6.87~109.33배 높은 것으로 나타났다. 특히 성엽에서는 석위의 억제활성이, 근경에서는 꿩고비의 <TEX>${\alpha}$</TEX>-glucosidase 억제활성이 가장 높았다. <TEX>${\alpha}$</TEX>-Glucosidase 활성의 50%를 억제하기 위한 성엽과 근경의 필요 생체량은 공히 꿩고비(각 0.35, 0.27 mg)에서 가장 적은 것으로 나타났다. 성엽의 경우는 석위의 <TEX>$IC_{50}$</TEX> 값이 가장 높았으나 가용성 고형분의 함량이 꿩고비에 비해 2.4배 낮아, 오히려 꿩고비의 경제성이 더 높은 것을 알 수 있었다. 본 연구의 결과 꿩고비는 적은 생체량으로도 높은 <TEX>${\alpha}$</TEX>-glucosidase 억제활성을 나타내기 때문에 경제적인 천연 <TEX>${\alpha}$</TEX>-glucosidase 저해제 소재로써 개발 가치가 매우 높은 것을 알 수 있었다. This study was conducted not only to analyze <TEX>${\alpha}$</TEX>-glucosidase inhibition activity with fronds and rhizomes of nine Pteridophyte species, but also to select the plant materials suitable for natural <TEX>${\alpha}$</TEX>-glucosidase inhibitor. Harvested rhizomes and fronds were washed, freeze-dried and grinded. After conducting ultrasonification extraction for 30 minutes in ultrasonic water tank with 100% methanol solvent, and vacuum filtration, <TEX>${\alpha}$</TEX>-glucosidase inhibition activity was measured. Acarbose was used as the positive control. After mixing <TEX>$100{\mu}L$</TEX> of 0.7 unit <TEX>${\alpha}$</TEX>-glucosidase enzyme solution into <TEX>$50{\mu}L$</TEX> of extract and reacting them at <TEX>$37^{\circ}C$</TEX> for 10 minutes, <TEX>$50{\mu}L$</TEX> of 1.5 mM <TEX>${\rho}$</TEX>-NPG solution was taken and reacted at <TEX>$37^{\circ}C$</TEX> for 20 minutes. The reaction was stopped with 1 mL of 1 M <TEX>$Na_2CO_3$</TEX> and absorbance was measured in 405 nm. With the regression analysis, the content of solubility solids (the value of <TEX>$IC_{50}$</TEX>) which can inhibit 50% of 0.7 unit <TEX>${\alpha}$</TEX>-glucosidase solution's activity was investigated. The frond (<TEX>$IC_{50}=14.00{\sim}913.33{\mu}g{\cdot}mL^{-1}$</TEX>) and rhizome extracts (<TEX>$IC_{50}=12.93{\sim}205.84{\mu}g{\cdot}mL^{-1}$</TEX>) of nine Pteridophyte species showed higher <TEX>${\alpha}$</TEX>-glucosidase inhibition activity in comparison with acarbose (<TEX>$IC_{50}=1413.70{\mu}g{\cdot}mL^{-1}$</TEX>). The extracts of fronds and rhizomes showed higher value than acarbose by 1.55~100.98 and 6.87~109.33 times each. Especially, <TEX>${\alpha}$</TEX>-glucosidase inhibition activities of Pyrrosia lingua in fronds and Osmunda cinnamomea var. fokiensis in rhizomes were the highest. The necessary biomass of fronds and rhizomes for inhibiting 50% of <TEX>${\alpha}$</TEX>-glucosidase activity showed the lowest value, 0.35, 0.27 mg each, in O. cinnamomea var. fokiensis. <TEX>$IC_{50}$</TEX> value of P. lingua was the highest among fronds of nine Pteridophyte species, but content of soluble solids was 2.4 times less than O. cinnamomea var. fokiensis. So frond of O. cinnamomea var. fokiensis is more economic in comparison with P. lingua. As the result of this study, O. cinnamomea var. fokiensis showed high <TEX>${\alpha}$</TEX>-glucosidase inhibition activity even with small biomass. Therefore it was considered to be high-valued economic material as natural <TEX>${\alpha}$</TEX>-glucosidase inhibitor.

Double-Capon and double-MUSICAL for arrival separation and observable estimation in an acoustic waveguide

Recent developments in shallow water ocean acoustic tomography propose the use of an original configuration composed of two source-receiver vertical arrays and wideband sources. The recording space thus has three dimensions, with two spatial dimensions and the frequency dimension. Using this recording space, it is possible to build a three-dimensional (3D) estimation space that gives access to the three observables associated with the acoustic arrivals: the direction of departure, the direction of arrivals, and the time of arrival. The main interest of this 3D estimation space is its capability for the separation of acoustic arrivals that usually interfere in the recording space, due to multipath propagation. A 3D estimator called double beamforming has already been developed, although it has limited resolution. In this study, the new 3D high-resolution estimators of double Capon and double MUSICAL are proposed to achieve this task. The ocean acoustic tomography configuration allows a single recording realization to estimate the cross-spectral data matrix, which is necessary to build high-resolution estimators. 3D smoothing techniques are thus proposed to increase the rank of the matrix. The estimators developed are validated on real data recorded in an ultrasonic tank, and their detection performances are compared to existing 2D and 3D methods.

Towards an understanding and control of cavitation activity in 1 MHz ultrasound fields

Various industrial processes such as sonochemical processing and ultrasonic cleaning strongly rely on the phenomenon of acoustic cavitation. As the occurrence of acoustic cavitation is incorporating a multitude of interdependent effects, the amount of cavitation activity in a vessel is strongly depending on the ultrasonic process conditions. It is therefore crucial to quantify cavitation activity as a function of the process parameters. At 1MHz, the active cavitation bubbles are so small that it is becoming difficult to observe them in a direct way. Hence, another metrology based on secondary effects of acoustic cavitation is more suitable to study cavitation activity. In this paper we present a detailed analysis of acoustic cavitation phenomena at 1MHz ultrasound by means of time-resolved measurements of sonoluminescence, cavitation noise, and synchronized high-speed stroboscopic Schlieren imaging. It is shown that a correlation exists between sonoluminescence, and the ultraharmonic and broadband signals extracted from the cavitation noise spectra. The signals can be utilized to characterize different regimes of cavitation activity at different acoustic power densities. When cavitation activity sets on, the aforementioned signals correlate to fluctuations in the Schlieren contrast as well as the number of nucleated bubbles extracted from the Schlieren Images. This additionally proves that signals extracted from cavitation noise spectra truly represent a measure for cavitation activity. The cyclic behavior of cavitation activity is investigated and related to the evolution of the bubble populations in the ultrasonic tank. It is shown that cavitation activity is strongly linked to the occurrence of fast-moving bubbles. The origin of this “bubble streamers” is investigated and their role in the initialization and propagation of cavitation activity throughout the sonicated liquid is discussed. Finally, it is shown that bubble activity can be stabilized and enhanced by the use of pulsed ultrasound by conserving and recycling active bubbles between subsequent pulsing cycles.

Use of ultrasonic waves in sub-cooled boiling

This work focuses on the use of ultrasounds in heat transfer fields. Under particular conditions, ultrasonic waves induce a convection coefficient increase. This initial research work, indicates that there are some practical applications in the cooling of the latest generation electronic components.In the first part of this paper, some background on this subject is reported. The ultrasound's influence on heat transfer rate has been observed since the 60's: different authors studied the cooling effect due to ultrasonic waves from different heat transfer regimes. The most investigated configuration was a thin platinum wire immersed in water. Later, a bibliographic research on possible practical applications of ultrasounds was carried out. This research focused in particular on the issue for 3D highly integrated electronic components. For these systems the thermal problem is a major challenge, because they cannot exceed critical temperatures, after which they could be damaged irreversibly. On the basis of our experimental results, ultrasounds could represent a valid means to overcome these thermal problems.Finally, the paper presents a series of experiments performed in the Thermal-Fluid- Dynamic Lab at the Energy and Engineering Systems Department of the University of Pisa. The experiments provide systematic evidence of ultrasonic waves effects, on free convection heat transfer, from a heated circular cylinder to sub-cooled water, at atmospheric pressure. Many variables involved in the heat transfer rise were tested, for example: the ultrasonic generator's power, the position of the heater inside the ultrasonic tank, the variation of the water sub-cooling degree, as function of the heat flux needed dissipating. The aim of the experiment was to find out the set of optimal conditions, in order to successively apply all the results to real packaging systems, as mentioned before. The maximum increase in the heat transfer coefficient, due to ultrasonic waves, was 57%.

Double multiple signal characterization active large band (D-MUSICAL) for extraction of observable in acoustic tomography

In the ocean, the acoustic propagation is characterized by different arrivals. Each arrival is characterized by its observables: amplitude, arrival time, emission, and reception angles. To achieve ocean acoustic tomography, a method to separate arrivals and extract observables has been developed. Two vertical arrays are used: a source and a receive array. Until now, the double-beamforming algorithm has been used to extract observables. It allows to go from the initial (time–source depth–receiver depth) domain to the beamformed domain (time–source angle–receive angle). This algorithm is efficient thanks to the 3-D domain of estimation but shows resolution limitation in the angle domain. To improve wave separation, we develop and apply a high-resolution algorithm based on MUSIC principle, in the same 3-D domain. The proposed method, called Double-MUSICAL, is the extension on the emission angle of the 2-D MUSIC Acitve Large band method (MUSICAL). Its principle is to separate the recording space onto the two orthogonal signal and noise spaces. We present results on real data recorded in an ultrasonic tank and show that the developed method better detects and separates the first arrivals than double beamforming.

Azimuthal Fourier mode decomposition of generic incident fields in the frequency domain: Computational model and results

The 3-D scattering from axisymmetric objects illuminated by nonaxisymmetric incident acoustic fields can be computed efficiently using finite element models, in which the field variables are decomposed via azimuthal Fourier series expansions. The number of azimuthal modes needed is determined by the convergence of the decomposition of the incident field. For simple cases, the field decomposition can be described analytically. For more complex incident fields, however, a closed form azimuthal Fourier series representation of the incident field is often not possible. A pre-processing step is presented, in which the incident field is decomposed numerically at the Gauss points on the wet surface of the target. This approach makes it possible to treat general cases, such as scattering from objects included inside heterogeneous media, at shallow grazing angle, when the symmetry axis of the object is not perpendicular to the interface between the two media. Other applications include decomposing the boundary scattered field re-incident on an object. The model is applied to scattering from a 2:1 aluminum cylinder, included in a fast fluid medium above a slow fluid medium, with the source in the slow medium, and the results are compared to ultrasonic tank measurements. [Work supported by ONR/ONRG.]

Effects of Ultrasounds on the Heat Transfer Enhancement From a Circular Cylinder to Distilled Water in Subcooled Boiling

The main aim of this work is to investigate experimentally the influence of ultrasonic waves, on the heat transfer enhancement, from a stainless steel circular cylinder to distilled water, in subcooled boiling conditions. This study has carried on for a few years at the Department of Energetics “L.Poggi.” The effect was observed since the 1960s: Different authors had investigated the cooling effect due to the ultrasonic waves at different heat transfer regimes, especially from a thin platinum wire to water. They had found out that the highest heat transfer coefficient enhancement was in subcooled boiling conditions. So this paper has the purpose to clarify the physical phenomenon and optimize a large range of variables involved in the mechanism. It reports the experimental results obtained with ultrasound at the frequency of 38 kHz, at two different subcooling degrees, ΔTsub=25°C and 35°C. The heat fluxes applied on the cylinder, the ultrasonic generator power Pgen, and also the placement of the heater inside the ultrasonic generator tank were varied. The ultrasonic waves seem to be very useful for a practical application in the last generation electronic components’ cooling: They need dissipating huge heat fluxes and avoiding high temperatures (≈150°C), after that they could damage themselves.

Effects of ultrasonic waves on the heat transfer enhancement in subcooled boiling

This work represents an experimental basic research aimed to investigate the influence on the heat transfer rate of the ultrasounds, in free convection and in presence of liquid. In fact the ultrasonic waves induce, thanks to vibrations, turbulence on the dynamic field, and so an increase of the convection coefficient. The heater is a circular cylinder, immersed in distilled water, and warmed up by Joule effect. This study has carried on for 1 year at Energetics Department “L. Poggi”. The effect was observed since 1960s: different authors had studied the cooling effect due to the ultrasonic waves at different heat transfer regimes, especially from a thin platinum wire to water. We have chosen to investigate the subcooled boiling regime, because this one is the best condition for the heat transfer enhancement, according to the scientific literature. We have carried out a wide experimental study, varying the different water subcooling degrees, the ultrasonic generator power, the ultrasound frequency and the placement of the heater inside the ultrasonic tank, in function of the range of the values of heat flux per unit surface needed dissipating. These values were supplied us by a possible practical application of the ultrasonic streaming: the cooling of 3D highly integrated electronic components. These packaging systems should have to provide all future devices, such as electronics, actuators, sensors and antenna. In fact, for these systems the thermal problem is a critical challenge, because they do not have to overtake critical temperature, after that they could damage irreversibly. Moreover, the traditional cooling systems used in electronic do not seem to be useful for them. On the contrary, the results obtained with ultrasounds, allow heat transfer coefficient enhancement of about 50% to be reached. The purpose is to find out the set of optimal conditions, in order to apply successively all the results to a real packaging system.

Inverting for surface displacement fields using directly measured point-to-point sensitivity kernels.

The effect of surface perturbations on underwater acoustic fields has been directly measured in an ultrasonic tank experiment. High-frequency transducer arrays of 64 elements each are placed 600 mm apart, submerged in ~50 mm of water. A point perturbation is used to displace the surface sequentially in 1-mm steps between the two arrays. At each position a 3.8-MHz signal is transmitted from the source array (round-robin), and the response recorded on the receive-aray, both with and without the presence of the surface probe. The difference between these two measurements yields the point-to-point acoustic sensitivity to that perturbation. These data are explored with respect to inferring the surface structure through both linear full-wave inversions and double-beamforming.

Shallow water tomography: Ray theory vs travel-time sensitivity kernels.

In underwater acoustics, ray tomography is the classical method used to estimate velocity variations, but recently. Travel-Time Sensitivity Kernels (TSK) approaches have been developed. In this paper, we deal with TSK for two source-receive arrays in an acoustic waveguide for shallow water tomography. As a first step, we show that separation of the different raypaths is improved by using a recently proposed new array processing [time-delay double beamforming (DBF) algorithm]. DBF consists of changing the 3-D data space from source depth, receiver depth and time into a new 3-D space related to ray propagation expressed by the beamformed variables, source angle, receive angle and time. As a consequence, each eigenray of the multipath propagation for a source-receiver couple can be identified and separated through DBF. In this context of DBF, the TSK is no longer point-to-point as usual, but relies on all source-receiver time series. Kernels are computed using the fact that the processed signal is a linear combination of time-delayed signals between all sources and receivers. Results in simulated data and in real datasets recorded in an ultrasonic tank prove that combination of TSK and DBF increases the resolution and robustness performance of shallow-water acoustic tomography.

Ultrasound-aided leather dyeing: a preliminary investigation on process parameters influencing ultrasonic technology for large-scale production

The application of ultrasound to leather processing has a significant role for more efficient and advanced manufacturing techniques for leather production. The effect of important process parameters for scale-up such as mechanical agitation, float, and concentration of dye bath has been experimentally examined. The results indicate that float level and dye bath concentration has significant effect on exhaustion of dye. There is no appreciable improvement due to mechanical agitation over the effect of ultrasound in leather dyeing. Dyeing of chrome-tanned wet-blue leather has been carried out directly in the ultrasonic tank with larger area of sample for scale-up possibility. The results indicate notable improvement (1.6-fold) in dye exhaustion as compared to dyeing in process vessel immersed in the ultrasound tank. This is also equivalent to 4.3-fold increase due to ultrasound as compared to control process without ultrasound at static condition. Ultrasound-aided dyeing of vegetable-tanned (EI) leather shows sixfold improvement as compared to control process. Acoustic cavitation energy in the ultrasonic tank, another important parameter for the scale-up, has been measured and the results indicate that ~60% acoustic energy is absorbed by leather in the process. Influence of ultrasound on dye aggregate size, an important parameter for diffusion, was also studied and found to be beneficial. Different ultrasonic equipments such as ultrasonic tank or ultrasonic probe have been tested and compared for their efficacy. Mass balance for ultrasonic leather dyeing process was performed and compared with control processes. Preliminary techno economic cost benefit analysis indicates positive trend for ultrasonic dyeing as compared to conventional drumming process. Savings in dye due to the use of ultrasound yield significant profit taking into account of ultrasonic energy cost, with a payback period for ultrasonic equipment cost. Therefore, the use of ultrasound in leather processing is a potential viable option for tanners in near future as advanced technology.

Observe multibubble cavitations in the ultrasonic cleaning tank

A cylindrical ultrasonic cleaning tank radiated by a PZT with a large horn operated at 27.3 kHz is employed to investigate the manifestations of cavitation in the present research. The characteristics of this cleaning system are analyzed using experimental methods. In this cleaning tank, the nonuniformity of vibration velocity on the radiation surface induces the Eckart streaming, which can eliminate the effect of a standing wave on cleaning efficiency. Fresh tap water and degassed water are employed as test liquids in this research. In tap water, conical streaming is observed as the input voltage of the transducer is increased over 100 V. The structure of conical streaming is anatomized. Its shape varies with the change of input voltage. In degassed water, ultrasonic fireworks are observed and special attention is paid to their subsequences, snowflake bubble clouds and water jet.

Experimental demonstration of time reversed reverberation focusing in an oceanic waveguide

The robust focusing and pulse compression provided by time reversal techniques may be exploited for active sonar. Backscattering from the rough water–bottom interface can be used as a surrogate probe source [Lingevitch et al., J. Acoust. Soc. Am. 111, 2609–2614]. This method uses a selected time-gated portion of the reverberation signals (or backscattered signals) to provide a transfer function between a time-reversing array (TRA) and a corresponding range interval on the bottom. The potential of a TRA for studying the application of shallow water bottom scattering is investigated experimentally using both sea-data collected in July 2004 in the Mediterranean sea off the Italian coast, and ultrasonic water tank data.

Ultrasonic Inspection of Bridge Hanger Pins

Ultrasonic inspection is currently one of the most common and reliable methods used in the inspection of hanger pins in pin-and-hanger bridge structures. Recently, a pin-and-hanger connection on a heavily traveled truck route in the Midwest showed visual indications of being deficient. Field contact ultrasonic inspections were performed on the remaining pin connections. The field inspections indicated that a number of the pins contained cracks or significant wear grooves at the pin shear planes, or both. These pins were replaced and sent to the FHWA’s Nondestructive Evaluation Validation Center for further testing in an ultrasonic immersion tank. The results of the contact and immersion tank ultrasonic studies were nearly identical. Both methods found two pins that contained transverse cracks at the level of a shear plane, with one of these cracks encompassing a majority of the pin cross section. Clearly, for the conditions found in the study, field contact ultrasonics can accurately locate defects in hanger pins.