scholarly journals Inactivation of Algae and Plankton by Ultrasonic Cavitation

2021 ◽  
Vol 13 (12) ◽  
pp. 6769
Author(s):  
Atsushi Honda ◽  
Fumiya Sugino ◽  
Ken Yamamoto
Keyword(s):  
Shear Stress ◽  
Ultrasonic Waves ◽  
Ultrasonic Cavitation ◽  
Treatment Technology ◽  
Extraction Technology ◽  
Resonance Model ◽  
Cavitation Bubbles ◽  
Wide Range ◽  
Partial Damage ◽  
Processing Mechanism

Microbial treatment by ultrasonic waves has been attracting attention as a useful water treatment technology because it does not use special chemicals and the equipment is simple. In addition, because microbial cells are destroyed during treatment, it can be applied to ingredient extraction technology. Although ultrasonic cavitation bubbles are thought to be involved in the processing mechanism, the details of the mechanism remain unclear. The purpose of this study was to elucidate the destruction mechanism of algae, microcapsules, and plankton by ultrasonic waves. Each sample was irradiated with ultrasonic waves over a wide range of frequencies, and frequency dependence was observed in all the samples. For algae and microcapsules, we matched the frequencies against the resonance frequency calculated based on the mechanical resonance model using adjacent ultrasonic cavitation bubbles. As a result, a good match was found. For plankton, partial damage to the shape was observed after ultrasonic irradiation, suggesting that shear stress, which is a local action caused by bubbles, was involved. By estimating the shear stress value based on the vibration equation of bubble, it was confirmed that the tendencies match.

Development of PEF extraction technology by Maguin

2015 ◽  
pp. 758-760
Author(s):  
Romain Delecourt ◽  
Loïc Marsal
Keyword(s):  
Sugar Beet ◽  
Electric Field ◽  
Pulsed Electric Field ◽  
Extraction Technology ◽  
Application System ◽  
Wide Range ◽  
Type Machine

Maguin (France) is still active in the application of pulsed electric field (PEF) technology. After having carried out successful tests on a 10 t/h pilot screw-type machine on sugar beet cossettes, a new application system based on a roller technology has been developed. This technology allows a wide range of application due to its flexibility with flowrates and materials. A variety of process schemes are proposed to ensure the best performance of the PEF technology.

scholarly journals A Novel Ultrasonic TOF Ranging System Using AlN Based PMUTs

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 284
Author(s):  
Yihsiang Chiu ◽  
Chen Wang ◽  
Dan Gong ◽  
Nan Li ◽  
Shenglin Ma ◽  
...  
Keyword(s):  
Clock Cycle ◽  
High Accuracy ◽  
Ultrasonic Waves ◽  
Oxide Semiconductor ◽  
Average Error ◽  
Cmos Process ◽  
Clock Frequency ◽  
Time Frequency ◽  
Range Finding ◽  
Wide Range

This paper presents a high-accuracy complementary metal oxide semiconductor (CMOS) driven ultrasonic ranging system based on air coupled aluminum nitride (AlN) based piezoelectric micromachined ultrasonic transducers (PMUTs) using time of flight (TOF). The mode shape and the time-frequency characteristics of PMUTs are simulated and analyzed. Two pieces of PMUTs with a frequency of 97 kHz and 96 kHz are applied. One is used to transmit and the other is used to receive ultrasonic waves. The Time to Digital Converter circuit (TDC), correlating the clock frequency with sound velocity, is utilized for range finding via TOF calculated from the system clock cycle. An application specific integrated circuit (ASIC) chip is designed and fabricated on a 0.18 μm CMOS process to acquire data from the PMUT. Compared to state of the art, the developed ranging system features a wide range and high accuracy, which allows to measure the range of 50 cm with an average error of 0.63 mm. AlN based PMUT is a promising candidate for an integrated portable ranging system.

Roughness Element Geometry Required for Wind Tunnel Simulations of the Atmospheric Wind

1977 ◽  
Vol 99 (3) ◽  
pp. 480-485 ◽  
Author(s):  
I. S. Gartshore ◽  
K. A. De Croos
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Wind Tunnel ◽  
Roughness Element ◽  
Three Dimensional ◽  
Wall Stress ◽  
Wide Range ◽  
Drag Plate ◽  
Rough Boundaries ◽  
Single Figure

Using a data correlation for the wall stress associated with very rough boundaries and a semi-empirical calculation method, the shape of boundary layers in exact equilibrium with the roughness beneath them is calculated. A wide range of roughness geometries (two- and three-dimensional elements) is included by the use of equivalent surfaces of equal drag per unit area. Results can be summarized in a single figure which relates the shape factor of the boundary layer (its exponent if it has a power law velocity profile) to the height of the roughness elements and their spacing. New data for one turbulent boundary layer developing over a long fetch of uniform roughness is presented. Wall shear stress, measured directly from a drag plate is combined with boundary layer integral properties to show that the shear stress correlation adopted is reasonably accurate and that the boundary layer is close to equilibrium after passing over a streamwise roughness fetch equal to about 350 times the roughness element height. An example is given of the way in which roughness geometry may be chosen from calculated equilibrium results, for one particular boundary layer thickness and a shape useful for simulating strong atmospheric winds in a wind tunnel.

scholarly journals Entropy-Based Shear Stress Distribution in Open Channel for all types of Flow using Experimental Data

2021 ◽  
Author(s):  
Hae Seong Jeon ◽  
Ji Min Kim ◽  
Yeon Moon Choo
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Turbulent Flow ◽  
Correlation Coefficient ◽  
Open Channel ◽  
Shear Stress Distribution ◽  
Entropy Theory ◽  
Tractive Force ◽  
Design Standards ◽  
Wide Range

Abstract Korea’s river design standards set general design standards for river and river-related projects in Korea, which systematize the technologies and methods involved in river-related projects. This includes measurement methods for parts necessary for river design, but do not include information on shear stress. Shear Stress is to one of the factors necessary for river design and operation. Shear stress is one of the most important hydraulic factors used in the fields of water especially for artificial channel design. Shear stress is calculated from the frictional force caused by viscosity and fluctuating fluid velocity. Current methods are based on past calculations, but factors such as boundary shear stress or energy gradient are difficult to actually measure or estimate. The point velocity throughout the entire cross section is needed to calculate the velocity gradient. In other words, the current Korea’s river design standards use tractive force, critical tractive force instead of shear stress because it is more difficult to calculate the shear stress in the current method. However, it is difficult to calculate the exact value due to the limitations of the formula to obtain the river factor called the tractive force. In addition, tractive force has limitations that use empirically identified base value for use in practice. This paper focuses on the modeling of shear stress distribution in open channel turbulent flow using entropy theory. In addition, this study suggests shear stress distribution formula, which can be easily used in practice after calculating the river-specific factor T. and that the part of the tractive force and critical tractive force in the Korea’s river design standards should be modified by the shear stress obtained by the proposed shear stress distribution method. The present study therefore focuses on the modeling of shear stress distribution in open channel turbulent flow using entropy theory. The shear stress distribution model is tested using a wide range of forty-two experimental runs collected from the literature. Then, an error analysis is performed to further evaluate the accuracy of the proposed model. The results revealed a correlation coefficient of approximately 0.95–0.99, indicating that the proposed method can estimate shear stress distribution accurately. Based on this, the results of the distribution of shear stress after calculating the river-specific factors show a correlation coefficient of about 0.86 to 0.98, which suggests that the equation can be applied in practice.

scholarly journals Investigation of Impact Loads Caused by Ultrasonic Cavitation Bubbles in Small Gaps

IEEE Access ◽  
2018 ◽  
Vol 6 ◽  
pp. 64622-64629 ◽  
Author(s):  
Fushi Bai ◽  
Kai-Alexander Saalbach ◽  
Liang Wang ◽  
Jens Twiefel
Keyword(s):  
Ultrasonic Cavitation ◽  
Impact Loads ◽  
Cavitation Bubbles

Extension of the Friction Mastercurve to Limiting Shear Stress Models

2003 ◽  
Vol 125 (4) ◽  
pp. 739-746 ◽  
Author(s):  
B. Jacod ◽  
C. H. Venner ◽  
P. M. Lugt
Keyword(s):  
Shear Stress ◽  
Friction Coefficient ◽  
Numerical Simulations ◽  
Coefficient Of Friction ◽  
Rheological Model ◽  
Operating Conditions ◽  
Limiting Shear Stress ◽  
Wide Range ◽  
Two Parameters ◽  
Stress Models

A previous study of the behavior of friction in EHL contacts for the case of Eyring lubricant behavior resulted in a friction mastercurve. In this paper the same approach is applied to the case of limiting shear stress behavior. By means of numerical simulations the friction coefficient has been computed for a wide range of operating conditions and contact geometries. It is shown that the same two parameters that were found in the Eyring study, a characteristic shear stress, and a reduced coefficient of friction, also govern the behavior of the friction for the case of limiting shear stress models. When the calculated traction data is plotted as a function of these two parameters all results for different cases lie close to a single curve. Experimentally measured traction data is used to validate the observed behavior. Finally, the equations of the mastercurves for both types of rheological model are compared resulting in a relation between the Eyring stress τ0 and the limiting shear stress τL.

Tensile Properties, Hardness and Micro Structural Analysis of Al 6061 – SiCP Metal Matrix Composites Fabricated by Ultrasonic Cavitation Approach

2012 ◽  
Vol 622-623 ◽  
pp. 1275-1279
Author(s):  
L. Poovazhagan ◽  
K. Kalaichelvan ◽  
D. Shanmugasundaram
Keyword(s):  
Structural Analysis ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Average Particle Size ◽  
Ultrasonic Cavitation ◽  
Average Particle ◽  
Matrix Composites ◽  
Weight Percentage ◽  
Al 6061 ◽  
Wide Range

The combined use of ultrasonic cavitation and mechanical stirring to disperse the silicon carbide particles (SiCp) in molten aluminum alloys has been studied. Composite materials with various weight percentage of Al 6061 alloy (matrix) and SiCp (reinforcement, average particle size 10 micrometers) were fabricated. The microstructure of the composites was investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The micro structural analysis validates the good dispersion of SiCp in the metal matrix. The tension test results reveal that the tensile strength of the as-cast metal matrix composites (MMCs) have been improved significantly for the 5 and 10 weight percentage of SiCp and then decreases. The hardness of MMCs increases and the ductility decreases as the particle percentage increases. The ultrasonic cavitation based fabrication is a novel route for producing wide range of MMCs.

scholarly journals Motion and Evaporation of Shear-Driven Liquid Films in Turbulent Gases

1991 ◽  
Author(s):  
S. Wittig ◽  
J. Himmelsbach ◽  
B. Noll ◽  
H. J. Feld ◽  
W. Samenfink
Keyword(s):  
Shear Stress ◽  
Liquid Film ◽  
Gas Phase ◽  
Film Flow ◽  
Phase Interface ◽  
Liquid Films ◽  
Numerical Code ◽  
Optical Instrument ◽  
Turbulent Characteristics ◽  
Wide Range

Detailed measurements of wavy liquid films driven by the shear stress of turbulent air flow are obtained for different air temperatures, air velocities and flow rates of the liquid. The experimental conditions are chosen from characteristic data of liquid film flow in prefilming airblast atomizers and film vaporization employing combustors. For the measurement of the local film thickness and film velocity a new optical instrument — based on the light absorption of the liquid — has been developed, which can be used at high temperatures with evaporation. The measured data of the gas phase and the liquid film are compared with the results of a numerical code using a laminar as well as a turbulent model for the film flow and a standard numerical finite volume code for the gas phase. The results utilizing the two models for the liquid film show that the film exhibits laminar rather then turbulent characteristics under a wide range of flow conditions. This is of considerable interest when heat is transferred across the film by heating or cooling of the wall. With this information the optical instrument can also be used to determine the local shear stress of the gas phase at the phase interface. Using time averaged values for the thickness, the velocity and the roughness of the film the code leads to relatively accurate predictions of the interaction of the liquid film with the gas phase.

scholarly journals KINETIKA DEGRADASI SELULOSA ASETAT DARI SABUT PINANG

2018 ◽  
Vol 1 (1) ◽  
pp. 24
Author(s):  
Intan Syahbanu ◽  
Annisa Anugraini ◽  
Husna Amalya Melati
Keyword(s):  
Polymer Solution ◽  
Cellulose Acetate ◽  
Intrinsic Viscosity ◽  
Degradation Kinetics ◽  
Molecular Size ◽  
Ultrasonic Waves ◽  
Degradation Rates ◽  
Wide Range ◽  
Degradation Rate Constant

Cellulose Acetate is a material with wide range in applications. Cellulose acetate may obtain from natural resources, such as areca fiber. Polymers should have uniform molecular weight for the applications and could be modify by ultrasonic waves. Ultrasonic treatment on polymer entangled with polymer degradation. In this research, degradation kinetics of cellulose acetate in acetone had been studied. Analysis was performed by determination of intrinsic viscosity in polymer solution system.  Intrinsic viscosity was successfully obtained by fitting data using Huggins equation, indicate molecular interaction in polymer solution should not be neglected.  Increasing in sonication time reducing the intrinsic viscosities as well as molecular size in solutions.  Degradation rate constant and reaction order were obtained 5,975x10-3(g.mL-1)0,1.min-1 and 1,0616, respectively.  Kinetics model was successful to determine the degradation rates of cellulose acetate on acetone by correlation coefficient (R2) at 0,966.

scholarly journals An investigation of accuracy and response time regarding processing mechanism of English relative clauses in EFL contexts

2020 ◽  
Vol 7 (1) ◽  
pp. 129-140
Author(s):  
Navid Nasrollahi Shahri ◽  
Masoud Motamedynia ◽  
Mohammad Ghazanfari
Keyword(s):  
English Learners ◽  
Relative Clauses ◽  
Sentence Comprehension ◽  
Native Speakers ◽  
English Literature ◽  
Wide Range ◽  
Reading Experiment ◽  
Native Speakers Of English ◽  
Processing Mechanism ◽  
English Relative Clauses

Sentence comprehension in EFL (English as a Foreign Language) contexts is influenced by many factors. One of the most important ones is the processing mechanism of relative clauses which can be analyzed in different frameworks by researchers. So far, a wide range of research has been conducted on the processing mechanism of relative clauses in a number of languages. The results have shown a tendency toward two major categories which have been proven to be of significance, namely subject preference and object preference. Studies conducted on native speakers of English, for instance, have demonstrated subject preference by the participants. Consequently, in this study, the researchers conducted a self-paced reading experiment employing Linger software, and the data were analyzed by using the SPSS Statistics version 25. It aims to investigate the processing mechanism of English relative clauses by Iranian EFL learners. The participants were nine males and 21 females of advanced English learners majoring in the English literature, all being native speakers of Farsi. The results indicate that that the correctness percentage of subject relative clauses, and also subject modifying ones, are significantly higher than that of object ones. The results also indicated that subject relatives were processed swifter than object relatives. Finally, the researchers discussed the reasons behind such a tendency among the participants of the experiment in terms of a number of theories and principles. The findings of this study are expected to be employed in language syllabus designing as well as in grading or sequencing of materials by educators and teaching material developers.

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