scholarly journals ENSURING THE MAXIMUM EFFICIENCY OF ULTRASONIC TECHNOLOGIES IN MEDIA WITH A LIQUID PHASE

2021 ◽  
pp. 62-70
Author(s):  
В.Н. Хмелев ◽  
С.Н. Цыганок ◽  
Р.В. Барсуков ◽  
М.В. Хмелев
Keyword(s):  
Liquid Phase ◽  
Oscillatory System ◽  
Wave Mode ◽  
Thin Layers ◽  
Maximum Efficiency ◽  
Ultrasonic Vibrations ◽  
Continuous Change ◽  
Technological Processes ◽  
Cavitation Effect ◽  
Dispersed Media

Актуальность исследований обусловлена отсутствие единого подхода к обеспечению ультразвукового воздействия с максимальной эффективностью при реализации различных технологических процессов в жидкодисперсных средах. Целью исследований является выявление условий обеспечения оптимальных режимов реализация различных технологических процессов под действием ультразвуковых колебаний в средах с преимущественно жидкой фазой с учетом особенностей, связанных с формированием ультразвуковых колебаний, их введением в различные по свойствам среды и реализацией самого воздействия с максимальной эффективностью. В качестве объекта исследований выступают ультразвуковые технологические аппараты для воздействия в режиме «развитой» кавитации с целью интенсификации технологических процессов в дисперсных средах с преимущественно жидкой фазой. В результате исследований на основе анализа формирования «развитой» кавитации выявлены наиболее эффективные режимы формирования колебаний, их введения в обрабатываемые среды и обеспечения максимально эффективного кавитационного воздействия, обеспечивающего заданные преобразования структуры и свойств обрабатываемых сред при воздействии на ограниченные и «безграничные» технологические объемы, воздействии в режиме стоячей волны и воздействии в тонких слоях жидкости. Проведенные исследования позволили выработать и рекомендовать для практического применения общий алгоритм управления ультразвуковым воздействием при реализации технологических процессов в дисперсных средах с преимущественно жидкой фазой за счет непрерывного изменения в режиме реального времени частоты и уровня напряжения электронного генератора, питающего ультразвуковую колебательную систему. The relevance of research is due to the lack of a unified approach to providing ultrasonic exposure with maximum efficiency in the implementation of various technological processes in liquid-dispersed media. The aim of the research is to identify the conditions for ensuring optimal modes for the implementation of various technological processes under the action of ultrasonic vibrations in media with a predominantly liquid phase, taking into account the peculiarities associated with the formation of ultrasonic vibrations, their introduction into media of different properties and the implementation of the action itself with maximum efficiency. The object of research is ultrasonic technological devices for exposure in the "developed" cavitation mode in order to intensify technological processes in dispersed media with a predominantly liquid phase. As a result of studies based on the analysis of the formation of "developed" cavitation, the most effective modes of formation of oscillations, their introduction into the processed media and provision of the most effective cavitation effect, providing the specified transformations of the structure and properties of the processed media when exposed to limited and "unlimited" technological volumes, exposure in a standing wave mode and exposure to thin layers of liquid. The studies carried out made it possible to develop and recommend for practical application a general algorithm for controlling ultrasonic action in the implementation of technological processes in dispersed media with a predominantly liquid phase due to a continuous change in real time of the frequency and voltage level of the electronic generator supplying the ultrasonic oscillatory system.

scholarly journals OBTAINING GRAPHENE STRUCTURES AND NANOPOLYMERS USING ULTRASONIC VIBRATIONS

2021 ◽  
pp. 74-83
Author(s):  
V. V. Rubanik ◽  
◽  
V. O. Savitsky ◽  
V. V. jr. Rubanik ◽  
V. F. Lutsko ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Ultrasonic Treatment ◽  
Polymer Composite Material ◽  
Optimal Time ◽  
Mutual Arrangement ◽  
Ultrasonic Vibrations ◽  
Ultrasonic Dispersion ◽  
Laboratory Equipment ◽  
Liquid Phase Exfoliation ◽  
Graphene Structures

Graphene-based polymer nanocomposites are considered a promising class of future materials. The degree of filling, the filler and binder nature, and the shape, size, and mutual arrangement of filler particles determine the properties of a polymer composite material. The destruction of nanoparticles aggregates occurs most effectively in liquid media under the action of ultrasonic vibrations. The authors proposed the technique and designed laboratory equipment for ultrasonic treatment of the finely-dispersed graphite suspension, carried out the ultrasonic treatment (UST) of finely-dispersed graphite powder. The suspensions based on graphite with a solvent were obtained. The authors carried out the experiments on producing graphene using the graphite liquid-phase exfoliation method at the ultrasonic treatment with different ultrasonic treatment times, analyzed experimental data, and selected the UST optimal time. The paper contains the results of the study of the effect of the graphite suspension base on the degree of ultrasonic liquid-phase exfoliation of graphite. The most effective synthesis of graphene structures using UST is synthesis from graphite suspensions based on dichloroethane, benzol, and dichlorobenzene. Graphene structures’ output ratio amounts to up to 66 %. The authors developed the technology for producing polymers modified with graphene structures using ultrasonic dispersion. Based on graphene synthesized by the graphite liquid-phase exfoliation, the authors obtained nanopolymers using ultrasonic vibrations, carried out DSC measurements, and studied their strength properties. The limit strength of elastic polymers is from 1.9 to 3.6 MPa at different concentrations of graphene inclusions. The residual elongation of samples within the deviation did not change and amounted to 200 %.

scholarly journals Rate-Limiting Steps of Dye Degradation over Titania-Silica Core-Shell Photocatalysts

Catalysts ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 583 ◽  
Author(s):  
Ariane Giesriegl ◽  
Jakob Blaschke ◽  
Shaghayegh Naghdi ◽  
Dominik Eder
Keyword(s):  
Dye Degradation ◽  
Sol Gel ◽  
Dye Adsorption ◽  
Thin Layers ◽  
Continuous Change ◽  
Uv Illumination ◽  
Rate Limiting Step ◽  
Sol Gel Process ◽  
Rate Limiting ◽  
Positively Charged

In this work, we employed a step-by-step sol-gel process to controllably deposit ultra-thin layers of SiO2 on anatase nanoparticles in the range between 0 and 1 nm. The deposition was confirmed by TEM, EDX, and ATR-FTIR (e.g., Ti-O-Si band at 960 cm-1). Zeta potential measurements unravelled a continuous change in surface charge density with increasing silica shell thickness. The photocatalysts were evaluated towards adsorption and degradation of positively-charged and negatively-charged dyes (methylene blue, methyl orange) under UV illumination. The growth mechanism follows the Stranski–Krastanov model with three thickness regimes: (a) Flat islands (first step), (b) mono/bilayers (second/third step), and (c) regular thick films (fourth/fifth step). The results suggest different rate limiting processes for these regimes: (a) For the thinnest scenario, acidic triple-phase boundaries (TPBs) increase the activity for both dyes with their accessibility being the rate limiting step; (b) for continuous mono/bilayers, dye adsorption on the negatively-charged SiO2 shells becomes the rate liming step, which leads to a stark increase in activity for the positively-charged MB and a decrease for MO; (c) for thicker shells, the activity decreases for both dyes and is limited by the charge transport through the isolating shells.

Effects of High Density Ultrasonic Field Coupling on the Microstructures and Properties of Al-Si Alloy

2011 ◽  
Vol 291-294 ◽  
pp. 1981-1988 ◽  
Author(s):  
Ying Long Li ◽  
Hua Ding ◽  
Fu Rong Cao
Keyword(s):  
Liquid Phase ◽  
Acoustic Streaming ◽  
Sound Intensity ◽  
Large Degree ◽  
Ultrasonic Field ◽  
High Density ◽  
Field Coupling ◽  
Cavitation Effect ◽  
Eutectic Si ◽  
Equiaxed Grains

The effects of high density ultrasonic field coupling on the microstructures and properties of Al-12Si alloy were investigated. It is shown that when the melt undergoes ultrasonic coupling processing prior to solidification, the nucleation rate of liquid phase can be raised to make α(Al) dendrite transform towards near equiaxed grains, the growth of Si phase is restrained and eutectic Si microstructure is refined due to acoustic streaming effect and thermal mechanism; When the melt undergoes ultrasonic coupling processing during the melt solidification, large degree of supercooling is produced in the liquid phase in the solidification interface front edge to reduce the critical radius of crystal nucleus and critical work of nucleation and break up, rupture by melting and refine the Si phase to improve obviously the strength of Al-12Si alloy due to its cavitation effect, acoustic streaming action and heat undulation; The crushing effect of ultrasonic coupling on Si phase occurs mainly during the crystallizing solidification and threshold sound intensity exists.

scholarly journals The process of interaction between abrasive disk and a workpiece while grinding under ultrasonic vibrations

2018 ◽  
Vol 224 ◽  
pp. 01017
Author(s):  
Alexandr Unyanin ◽  
Alexandr Khazov
Keyword(s):  
Surface Roughness ◽  
Analytical Approach ◽  
Mechanical Characteristics ◽  
Oscillatory System ◽  
High Amplitude ◽  
Grinding Force ◽  
Ultrasonic Vibrations ◽  
Pilot Studies ◽  
Abrasive Disk ◽  
High Level

This research includes the analysis of kinematic relations between abrasive disk grains and the workpiece in the abrading process while applying ultrasonic vibrations (USV) on the workpiece. Supposition, that applying vibrations lied in axes of abrasive disk increases efficiency of disk grinding, has been set. Analytical approach showed dependences for calculating the grinding force. These dependences include changing of disk grains microcutting kinematics and mechanical characteristics of workpieces while applying USV. The technique of pilot studies is given. For imposing on preparation of USV used the device in which it was one of links of oscillatory system that provides the minimum losses of energy USV and high amplitude of fluctuations of preparation. Field researches have shown, that applying USV lied in axes of abrasive disk decreased the grinding force, the wear of disk, and high-level parameters of the processed surface roughness.

scholarly journals VOCATIONAL TRAINING OF FUTURE SPECIALISTS IN THE FIELD OF TOURISM BASED ON PERSONALITY QUALITIES

2021 ◽  
Author(s):  
Ecaterina Lungu ◽  
◽  
Viorica Calugher ◽  
Gheorghe Braniste ◽  
◽  
...  
Keyword(s):  
Vocational Training ◽  
Training System ◽  
Tourism Industry ◽  
Maximum Efficiency ◽  
Professional Activity ◽  
Highly Qualified ◽  
Continuous Change ◽  
The Future ◽  
The University ◽  
Scientific Documentation

The current training system for specialists in the field of tourism is oriented towards the continuous change of society and tends to continuously increase the quality of provided services. One of the peculiarities of the specialties in the field of tourism is the impossibility to work within the limits of a narrow specialization, of major importance being the personality characteristics, which ensure maximum efficiency and success in the profession. The aim of the research is the study of the personality and professional qualities necessary for the future specialist in the field of tourism. The research methods applied in the study were: the method of scientific documentation, the questionnaire, the statistical-mathematical method. The main results of the research showed that students appreciate the most for the future profession the higher education in tourism, knowledge of technologies for organizing the tourism industry and the basics of psychology, which reflects the content of the vocational training process at the university. At the same time, the experience in the field is placed on the last positions, which reflects the low number of practical activities (performed only during the internship). Thus, students studying at the specialized faculty are aware of the importance and need for personal and professional qualities for the future professional activity and appreciate the importance of specialized knowledge and professional skills in becoming highly qualified specialists.

Effects of Ultrasonic Vibrations Given to an Electrode on the EDM Performance in Processing PCD

2012 ◽  
Vol 565 ◽  
pp. 394-399 ◽  
Author(s):  
Kiyoshi Suzuki ◽  
Takuya Takada ◽  
Zhi Rong Zhou ◽  
Takuya Okamichi ◽  
Manabu Iwai ◽  
...  
Keyword(s):  
Ultrasonic Vibration ◽  
Flexural Vibration ◽  
Copper Electrode ◽  
Experimental Results ◽  
Working Fluid ◽  
Vibration Modes ◽  
Ultrasonic Vibrations ◽  
Axial Vibration ◽  
Cavitation Effect ◽  
Vibrational Action

EDM machinability of PCD was investigated using a copper electrode giving ultrasonic vibrations. In this series of EDM experiments, three types of ultrasonic vibration modes were selected (axial vibration, flexural vibration and complex vibration). From the experimental results, it was found that EDM efficiency became 3 times higher than the ordinary EDM (no vibration given to the electrode) under the two specific vibration modes, namely, 1) the axial vibration (large) mode and 2) the complex vibration (axial vibration: large + flexural vibration: small) mode. Furthermore, it was shown that the effects resulted from not only the cavitation effect of the working fluid but also the vibrational action of the electrode itself.

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