Papers by Keyword: Ultrasound

Abstract: Initially, this work briefly outlines how ultrasound can modify and characterize the defect system in semiconductors. Then, the study experimentally examines the effect of different types of acoustic waves on the association of FeB pairs in monocrystalline silicon. The results reveal that as the frequency of longitudinal waves increases, the ultrasound's effectiveness in accelerating the association rate decreases. Conversely, exciting transverse waves show the opposite trend. The study also assesses the potential to obtain a positron-annihilation response from the FeB complex in silicon, highlighting the advantages of conducting such measurements under ultrasound loading of the crystal.

Abstract: The object of the study was the Ukrainian bentonite clays of the Cherkasy deposit (layer II of the Dashukivska area) and the Ilnytske deposit of the Transcarpathian region. Enrichment of clays with montmorillonite was carried out by the method of sedimentation of the coarsely dispersed phase. The natural type of montmorillonite and the nature of isomorphic substitutions in its structure were confirmed by X-ray diffractometric and complex thermal analyses. Activation of bentonite clay enriched with montmorillonite was carried out by the action of ultrasonic waves. The sorption capacity of activated and montmorillonite-enriched clays with respect to Cu²⁺ ions was assessed by the results of energy dispersive X-ray analysis. The ion exchange mechanism of sorption of Cu²⁺ ions was confirmed by the data of diffractometric X-ray analysis. The prospects for the use of enriched bentonite clays activated by ultrasonic waves are outlined.

Abstract: The key drivers of the growing interest in the recovery of local materials, particularly land and waste plants, are low-cost building materials, thermal comfort, decreased energy consumption, and decreased carbon dioxide polluting emissions. This work's primary objective is to test a bio-sourced composite material that takes the form of a block of unfinished soil that has been stabilized with cement and blended with wheat straw. This study is being done with the objective of examining the impact of this fiber at different weight percentages (0, 2, 3%, and 4%) on the mechanical behavior, durability, and thermophysical properties of the produced blocks. The results obtained indicated an increase in thermal conductivity, from 2.75 W/mK for the blocks without wheat straw fiber to 0.398 W/mK for those getting 4% of the wheat straw fiber, signifying an improvement in thermal insulation. While retaining the low performance threshold required by the earth construction standard, this improvement was accompanied by an average decrease in mechanical performance.

Abstract: This study focused on the optimization of methylene blue removal on a magnetic activated carbon from the carbon-rich agro-industrial residue, sugarcane bagasse, synthesized by microwave method. The adsorption process was assisted by ultrasound. The magnetic sugarcane bagasse activated carbon (MSB) was characterized by FTIR and SEM-EDX. Based on FTIR results, the functional groups found in magnetic sugarcane bagasse activated carbon are O-H, C=C, C-O, and Fe-O. The SEM results show that MSB is porous with a rough surface. In addition, EDX data found the presence of three main elements, namely C, O, and Fe. Response Surface Methodology (RSM) Box-Behnken Design was applied to analyze the effects of three parameters, including adsorbent dosage (50-100 mg/L), ultrasonic power (100-200 W), and contact time (30-60 min). The obtained optimum conditions of the adsorption process were the sonication power of 155.65 W, the adsorbent dosage of 89.77 mg/L, and the sonication time of 57,81 minutes. The results indicated that the parameters of adsorbent dosage, ultrasonic power, and contact time influenced the response (qe and methylene blue removal).

Abstract: One of the ways to develop existing methods of hardening is creation of hybrid technologies that combine the principles of chemical heat treatment and surface plastic deformation. This paper proposes a nitriding technology followed by ultrasonic treatment. As a result of such sequence, a surface layer is formed that has an increased hardness and depth of hardening, in comparison with combined methods used separately.

Abstract: The currents of n-p junctions and polarization effects caused by the capture processes of diffusion Si-receivers (detectors) of radiation exposed by ultrasound have been analyzed in this work. It was found that there are local concentrations of impurity atoms with an effective size l>6μm30μm in Si-n-p radiation receivers. They determine the behavior of the signal amplitude in different intervals of electric and temperature fields. It was found that at Е>1500V/cm and T>168K, the efficiency of collecting nonequilibrium charge carriers significantly increases and doublets of spectral α-lines and “humps” disappear at the temperature dependences of the signal amplitude. The main physical processes and mechanisms that determine the appearance of the phenomenon of "polarization" of Si-n-p-detectors were investigated. This phenomenon is caused by the existence of local gold atoms, which arise in the process of manufacturing technology of Si-n-p-receivers and act as effective trapping centers.

Abstract: Fetal Echocardiography is used for monitoring the fetal heart and for detection of Congenital Heart Disease (CHD). It is well known that fetal cardiac four chamber view has been widely used for preliminary examination for the detection of CHD. The end diastole frame is generally used for the analysis of the fetal cardiac chambers which is manually picked by the clinician during examination/screening. This method is subjected to intra and inter observer errors and also time consuming. The proposed study aims to automate this process by determining the frame, referred to as the Master frame from the cine loop sequences that can be used for the analysis of the fetal heart chambers instead of the clinically chosen diastole frame. The proposed framework determines the correlation between the reference (first) frame with the successive frames to identify one cardiac cycle. Then the Master frame is formed by superimposing all the frames belonging to one cardiac cycle. The master frame is then compared with the clinically chosen diastole frame in terms of fidelity metrics such as Dice coefficient, Hausdorff distance, mean square error and structural similarity index. The average value of the fidelity metrics considering the dataset used for this study 0.73 for Dice, 13.94 for Hausdorff distance, 0.99 for Structural Similarity Index and 0.035 for mean square error confirms the suitability of the proposed master frame extraction thereby avoiding manual intervention by the clinician. .

Abstract: Carbonatation represents one of the potential degradation processes whose can negatively affect the service life of constructions based on the inorganic binders. The carbonatation depth of the constructions when exposed to various environments is significantly dependent on the existing conditions. The most crucial parameters are the partial pressure of carbon dioxide and humidity. There were selected four environments for the deposition of samples made of the alkali-activated blast furnace slag mortars (exterior, interior, water and CO₂ chamber) in this study. These types of environments guarantee the variation of desired parameters influencing the carbonatation rate. The progress of carbonatation was evaluated with a selected technique in time intervals of 28; 56 and 84 days of the sample's exposition to the selected environments. The characterization was done using the destructive techniques (compressive and flexural strength, phenolphthalein method) as well as the non-destructive one like the Impact-Echo or the Ultrasound time passage measurement. The combination of these techniques allows to determine and evaluate the progress of carbonation without the destructive testing of the samples which is necessary for the real applications of these materials.

Abstract: The paper presents the results of numerical experimental studies of cutting titanium blanks using mathematical modeling programs, which make it possible to completely repeat technological processes in a computer (digital twin). The LS-DYNA product was used as a program to simulate the process of stock removal from titanium blank. It has been established that the use of this method adequately describes the cutting processes, including with the introduction of the energy of an ultrasonic field into the processing zone, can significantly reduce the duration of experimental research and evaluate the influence of the elements of the cutting mode and design parameters of the tool on the thermal power aspects of the formation of new surfaces of machine parts.

Abstract: Ultrasound-Assisted Extraction (UAE) was applied to enhance the bioactive compound extraction from the intact red sorghum grains using water as a green solvent that is relatively more available, safe, and less contaminant to the product application. The UAE performance of the ultrasonic probe with 60, 70, and 80% amplitude were compared to evaluate the effect of ultrasound amplitude. A mechanistic model was applied for quantitative evaluation of the UAE performance and prediction of the concentration of total phenolic (TP) and proanthocyanidin (PC) in the extract during the extraction. This research evaluated the effect of amplitude on the extraction rate, the parameters in the model, and the predicted TP and PC concentration from the mechanistic model approach. The wave enhanced the extraction by its propagation, cavitation bubble, and pericarp destruction. The mass transfer coefficient was stretched between 1.271×10^–2 - 1.345×10^–2 cm^–1/minutes for TP and 5.979×10^–3 - 8.262×10^–3 cm^–1/minutes for PC, while the distribution coefficient was 2.222×10^–2 -2.248×10^–2 grain/cm^–3 solvent for TP and 6.739×10^–2 - 7.946×10^–2 grain/cm^–3 solvent for PC. The highest performance resulted from 80% amplitude. The model worked precisely to predict the concentration of TP and PC of UAE, illustrating the amplitude’s effect in enhancing the UAE from its parameter values.