Papers by Keyword: Ultrasound

Abstract: The article describes the process efficiency of ultrasonic mechanical stabilization of details in comparison with the conventional thermal treatment. It is shown that ultrasonic treatment enhances the productivity and quality of manufactured details. As a result of the proposed stabilizing treatment the relaxation of residual stresses, the required geometry, such as waviness and ovality, as well as necessary mechanical properties are ensured.

Abstract: The aim of the study was to develop neural network model to predict the yield obtained from ultrasound-assisted anti-solvent crystallization of ibuprofen in terms of formulation and processing factors. The different factors of anti-solvent crystallization method, such as type of additive, concentration of additive, sonication time and harvesting time, were used as independent variables. The ibuprofen yield was used as response variable. The correlation between independent and response variables was investigated using feed forward-back propagation neural networks. The goodness of fit test and predictability were used for optimization of in silico models. The results revealed that the type of polyethylene glycol (PEG) was a critical factor that affected the response variable in different patterns. The best artificial neural networks (ANNs) model with a configuration of 3-4-1 for input, hidden, and output layers gave the r² of 0.7067 and 0.8729 and the root mean square error of 0.3693 and 0.2667 for the model using PEG 400 and PEG 4000, respectively. The predictive ability of these models was validated by a set of 4 formulations that were not included in the training set. The predicted and experimental of ibuprofen yields were correlated.

Abstract: TiB₂/7055 composite was synthesized by a new melt direct reaction from 7055-(Al-3B)-Ti system with ultrasound. The phase composition and the microstructures of the as-prepared samples were investigated by XRD, SEM and EDS. The result shows that no Al₃Ti phase is in existence. With the assistance of ultrasound, grains are significant refined. Moreover, the wettability between matrix and particles is improved. The shapes of TiB₂ particles are mainly hexagonal or near-spherical, and the size is about 500nm. TiB₂ particles are with uniform distribution. Compared with 7055Al matrix alloy, the tensile strength of the composite reaches 303MPa, increased by 10.2%. However, the elongation is 7.3%, decreased by 4.8%.

Abstract: In the present investigation, SiC reinforced ZE10 alloy composites were fabricated by direct chill casting assisted with ultrasonic vibration. Two kinds of SiC with a size of 50 nm and 2 μm were chosen. For comparison, ZE10 alloys with and without ultrasound were also fabricated. The microstructures and the distribution of SiC were examined by optical microscopy and scanning electron microscopy. Neutron diffraction was also used to identify the second phases in the composites. In addition, mechanical properties such as hardness, creep and compression were evaluated. The results show that SiC was successfully introduced into the magnesium matrix. After the addition of SiC, the mechanical properties of the composites exhibit a slight decrease, which might be due to the grain coarsening.

Abstract: The bubbles in the liquid will scatter and absorb the ultrasound, therefore the existence of bubbles will seriously affect the ultrasound propagation in the liquid medium inside the pipeline. This paper analyzes the influence of bubbles in the liquid on the performance of the ultrasonic flow meter, and the gas-liquid two-phase flow rate measurement experiments are implemented. Experimental results show that with the increase of the bubble volume fraction in the liquid, the measurement error of the ultrasonic flow meter increases. When the bubble volume fraction exceeds 1%, the transit-time difference method of measuring the flow rate is nearly useless.

Abstract: During conventional finishing textile processes it is necessary a big consumption both of water and energy. This aspectsare is imposed by the development process of thermo and mass transfer of finishing agents into the textile structure materials applied in dentistry (fibers, yarns, fabric, nonwovens). The intensification of transfer processes into the textile materials is realized in conventional finishing textile industry (washing, cleaning, and coloring) by using high work temperature. The negative result of this intervention and the presence of chemical substances without degradation mean the environment pollution by the pour out residual water with a great quantity of toxic substances. The recently laboratory scientific research showed that the use of ultrasonic systems in finishing textile materials contributes both to the acceleration of thermo and mass transfer and to the decreasing of active chemical substances. In this way the paper presents a finishing system based on ultrasonic processes which is composed by modules and specific hardware components.

Abstract: Ultrasound-assisted oxidative desulfurization (UAODS) of diesel fuel in H₂O₂/Heteropoly acid/Solvent systems, was investigated. Effects of solvent, catalyst, ultrasound and reaction temperature on the oxidation desulfurization of diesel fuel were investigated. When MPA/oil was 2%wt, methanol/diesel fuel was 20%wt, ultrasound power was 400 W and ultrasound time was 10 min, the sulfur content of diesel fuel was decreased from 211 ppm to 19 ppm. The use of ultrasonic irradiation in H₂O₂/Heteropoly acid/Solvent system significantly improved the efficiency of the oxidation reaction, and solvent was helpful to make the oxidative reaction happen in the same one phase.

Abstract: We developed new synthetic method of silver nanowire by reducing silver acetate precursor. Silver acetate could be easily synthesized by ultrasound irradiation to the mixture of non-toxic starting materials, only ethanol and silver (I) oxide. All of reaction was performed in relatively low temperature and it does not need any protective agents. The precursors had high aspect ratio needle-shaped morphology. They decomposed easily by heating up to 300 °C and then produce only silver without any residues. This process is expected to be new synthetic method of silver nanowire that doesn’t require any protective agents and emit much waste.

Abstract: In this study, Graphite Oxide (GO) and Ag/Graphene nanocomposites were synthesized by solid-liquid sonochemical reactions easily and briefly. GO was synthesized by means of Hummers method using sonication or stirring. From XRD patterns and FT-IR spectra, chemical and physical effects of ultrasound promoted the oxidation of Graphite. Ag/graphene nanocomposites were synthesized from GO and silver oxide by sonication. UV-vis spectra showed the peaks of Graphene oxide and Ag nanoparticle plasmon resonance absorption. EDX images and electron diffraction patterns confirmed Ag nanoparticles were decorated on Graphene sheets by ultrasound. Using sonication, GO and Ag/Graphene nanocomposites could be synthesized easily in short time.

Abstract: With the development of Internet and sensor network, relevant application have a more high desire for the positioning accuracy. Meanwhile, modern smartphones are a great platform for Location Based Services (LBS). While outdoor LBS for smartphones has proven to be very successful, indoor LBS for smartphones has not yet fully developed due to the lack of an accurate positioning technology. We present an accurate indoor positioning approach for commercial off-the-shelf (COTS ) smartphones that uses the innate ability of mobile phones to produce ultrasound, combined with Time-Difference-of-Arrival (TDOA) asynchronous trilateration. Ultrasonic signal transmission will cause ranging error, which may affect the precision of positioning. In order to solve this problem, this paper uses least squares straight line fitting method to compensate error and fix distance, then, uses weighted least squares methods to improve the positioning accuracy of the system.