scholarly journals Effect of ultrahigh-frequency electromagnetic field on the properties of associated liquids

2020 ◽  
Vol 100 (4) ◽  
pp. 75-84
Author(s):  
I.E. Stas’ ◽  
◽  
S.S. Pavlova ◽  
Keyword(s):  
Surface Tension ◽  
Electromagnetic Field ◽  
Evaporation Rate ◽  
Field Evaporation ◽  
Frequency Range ◽  
Field Frequency ◽  
Structure Of Water ◽  
Slowing Down ◽  
Field Action ◽  
Elec Tromagnetic Field

The influence of the electromagnetic field on the refractive index, evaporation rate and surface tension of wa-ter, propanol-1 and pentanol-1 solutions have been studied. It was shown that the properties of these liquids depend on the field frequency and the time of exposure. The action of the field on the structure of water and alcohols is selective; changes in their properties are due to frequencies that are individual for each liquid. Both deceleration and acceleration of the alcohols evaporation occurs depending on the frequency of the elec-tromagnetic field. Evaporation of the field exposed water is slowing down at all the studied frequency range. There is an increase in the surface tension for water and pentanol, and a decrease for propanol. The properties of alcohols return to their initial values, and the properties of the water remain unchanged after the termina-tion of the field action. Thermodynamic functions of surface water and propanol-1 have been calculated on the basis of the temperature dependence of the surface tension. It has been demonstrated that the total internal energy of the surface increases for water and reduces or propanol-1. This indicates the strengthening of the structure in an aqueous solutions and a weakening of intermolecular interaction in the propanol-1 medium.

ROLE OF NÉEL AND BROWNIAN RELAXATION MECHANISMS FOR WATER-BASED Fe3O4 NANOPARTICLE FERROFLUIDS IN HYPERTHERMIA

2010 ◽  
Vol 22 (05) ◽  
pp. 393-399 ◽  
Author(s):  
Xuefeng Zhang ◽  
Shihwei Chen ◽  
Huay-Min Wang ◽  
Shu-Ling Hsieh ◽  
Chun-Hsin Wu ◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Direct Reduction ◽  
Water System ◽  
Linear Increase ◽  
Fe3o4 Nanoparticle ◽  
Frequency Range ◽  
Field Frequency ◽  
Magnitude Range ◽  
Néel Relaxation

Hydrophilic Fe3O4 nanoparticles with a mean diameter size of 15 nm were synthesized by means of the direct reduction of FeCl3 and FeCl2 in an aqueous solution. The heating properties of Fe3O4 nanoparticles under an alternating magnetic field were investigated in a frequency range of 50–500 kHz and a magnitude range of 3.1–5.0 kA/m. To distinguish the roles of Néel and Brownian relaxation mechanisms, polydimethylsiloxane (PDMS) and water were employed as a medium, in which PDMS plays a significant role of eliminating the effect of Brownian relaxation. It is experimentally and theoretically confirmed that, for the Fe3O4 /water system, high-specific absorption rates are due to a combination of both mechanisms, with an enhanced contribution due to Néel relaxation with increasing frequency and magnitude of the alternating electromagnetic field. The contribution efficiency of Néel relaxation increases from 36–56% by increasing the electromagnetic field frequency from 50–300 kHz, and then retains a saturated value of ~ 56% at 300–500 kHz. Moreover, a linear increase of the contribution efficiency of Néel relaxation at 300 kHz was observed from 55–65% by increasing the magnitude of electromagnetic field at 3.1–5.0 kA/m. The current research can be widely-expanded to explain the electromagnetic heating effect of other ferrofluid systems.

Dielectric properties of wheat flour mixed with oat meal

2013 ◽  
Vol 27 (2) ◽  
pp. 175-180 ◽  
Author(s):  
D. Łuczycka ◽  
A. Czubaszek ◽  
M. Fujarczuk ◽  
K. Pruski
Keyword(s):  
Electromagnetic Field ◽  
Dielectric Loss ◽  
Wheat Flour ◽  
Loss Factor ◽  
Ash Content ◽  
Dielectric Loss Factor ◽  
Field Frequency ◽  
Impedance Analyzer ◽  
Sedimentation Value

Abstract Possibilities of using electric methods for determining admixtures of oat meal to wheat flour, type 650 are presented. In wheat flour, oat meal and mixtures containing 10, 20 and 30% of the oat meal, moisture, protein, starch and ash content, sedimentation value, yield and softening of wet gluten were determined. In samples containing 0, 5, 10, 15, 20, 25, 30 and 100% of oat meal, the dielectric loss factor and conductivity were determined using an impedance analyzer for electromagnetic field frequency ranging from 0.1-20 kHz. It was found that the dielectric loss factor varied for tested material. The best distinguishing between tested mixtures was obtained at the measuring electromagnetic field frequency of 20 kHz. The loss factor was significantly correlated with the yield of wet gluten and the sedimentation value, parameters indicating the amount and quality of gluten proteins in flour.

scholarly journals Influence of Magnetic Field on Evaporation Rate and Surface Tension of Water

2018 ◽  
Vol 2 (4) ◽  
pp. 68 ◽  
Author(s):  
Emil Chibowski ◽  
Aleksandra Szcześ ◽  
Lucyna Hołysz
Keyword(s):  
Magnetic Field ◽  
Surface Tension ◽  
Hydrogen Bonds ◽  
Room Temperature ◽  
Evaporation Rate ◽  
Water Evaporation ◽  
Water Molecules ◽  
Surface Tension Data ◽  
Ring Magnet ◽  
The Magnetic Field

Using neodymium ring magnets (0.5–0.65 T), the experiments on the magnetic field (MF) effects on water evaporation rate and surface tension were performed at room temperature (22–24 °C). In accordance with the literature data, the enhanced evaporation rates were observed in the experiments conducted in a period of several days or weeks. However, the evaporated amounts of water (up to 440 mg over 150 min) in particular experiments differed. The evaporated amounts depended partially on which pole of the ring magnet was directed up. The relatively strong MF (0.65 T) caused a slight decrease in surface tension (−2.11 mN/m) which lasted longer than 60 min and the memory effect vanished slowly. The surface tension data reduced by the MF action are reported in the literature, although contrary results can be also found. The observed effects can be explained based on literature data of molecular simulations and the suggestion that MF affects the hydrogen bonds of intra- and inter-clusters of water molecules, possibly even causing breakage some of them. The Lorentz force influence is also considered. These mechanisms are discussed in the paper.

scholarly journals Optimization Design of Thermal Test Waveguide Link for Communication Satellite

2018 ◽  
Vol 179 ◽  
pp. 03027
Author(s):  
Yu-jie SHAO ◽  
Yu Zhong-xi ◽  
Chun-lin DU ◽  
Jing WANG
Keyword(s):  
Electromagnetic Field ◽  
Optimization Design ◽  
Signal Loss ◽  
Signal Attenuation ◽  
Water Load ◽  
Electromagnetic Field Distribution ◽  
Structure Of Water ◽  
Power Meter ◽  
Thermal Test ◽  
Communication Satellite

Problems in structure of water load power meter and waveguide assemblies of the communication satellite transponder thermal test. This paper analyzes water load layout and reasons of signal attenuation, and then it proposes an optimization that put water load detached from satellite’s board. To ensure the reason of waveguide signal loss, this paper discusses the internal electromagnetic field distribution and currents on waveguide wall. the result of signal loss value showed that the new optimization can decrease signal attenuation value and shorten the process of crafts implementation.

Effects of Cross-Section Geometry of Capillary on the Evaporation From the Meniscus

2005 ◽  
Author(s):  
Songwan Jin ◽  
Choonghyo Choi ◽  
Kenneth S. Breuer ◽  
Jung Yul Yoo
Keyword(s):  
Surface Tension ◽  
Cross Section ◽  
Evaporation Rate ◽  
Rectangular Channel ◽  
Vortex Motion ◽  
Meniscus Shape ◽  
Four Corners ◽  
The Difference ◽  
Circular Capillary ◽  
Cross Section Geometry

Effects of cross-section geometry of capillary on the evaporation from the meniscus have been investigated by adopting several circular and rectangular capillaries. The evaporating meniscus shape, evaporation rate and flow near the evaporating meniscus of various liquids such as water, ethanol and methanol are determined. The shapes of water and ethanol menisci in circular capillary are quite different from each other due to the difference in surface tension. But the difference in meniscus shapes is relatively small in rectangular channel. The averaged evaporation fluxes in rectangular channel are much larger than that in circular capillary. The rotating vortex motion is observed near the evaporating menisci of ethanol and methanol except for the case of methanol in 200 × 20-μm capillary. The reason for this is considered to be the existence of the corner menisci at the four corners.

Parametrically forced gravity waves in a circular cylinder and finite-time singularity

2008 ◽  
Vol 599 ◽  
pp. 205-228 ◽  
Author(s):  
S. P. DAS ◽  
E. J. HOPFINGER
Keyword(s):  
Surface Tension ◽  
Circular Cylinder ◽  
Gravity Waves ◽  
Finite Time ◽  
Wave Breaking ◽  
Wave Amplitude ◽  
Frequency Range ◽  
Jet Formation ◽  
Time Singularity ◽  
Finite Time Singularity

In this paper we present results on parametrically forced gravity waves in a circular cylinder in the limit of large fluid-depth approximation. The phase diagram that shows the stability-forcing-amplitude threshold and the wave-breaking threshold has been determined in the frequency range of existence of the lowest axisymmetric wave mode. The instability is shown to be supercritical for forcing frequencies at and above the natural frequency and subcritical below in a frequency range where the instability and breaking thresholds do not coincide. Above the instability threshold, the growth in wave amplitude is exponential, but with an initial time delay. The wave-amplitude response curve of stationary wave motions exhibits steady-state wave motion, amplitude modulations and bifurcations to other wave modes at frequencies where the parametric instability boundary of the axisymmetric mode overlaps with the neighbouring modes. The amplitude modulations are either on a slow time scale or exhibit period tripling and intermittent period tripling, without wave breaking. In the wave-breaking regime, a finite-time singularity may occur with intense jet formation, a phenomenon demonstrated by others in fluids of high viscosity and large surface tension. Here, this singular behaviour with jet formation is demonstrated for a low viscosity and low kinematic surface tension liquid. The results indicate that the jet is driven by inertial collapse of the cavity created at the wave trough. Therefore, the jet velocity is determined by the wave fluid velocity but depends, in addition, on kinematic surface tension and viscosity as these affect the last stable wave crest shape and the cavity size.

Grain Refinement of Direct Chill Cast 7050 Aluminium Alloy with Low Frequency Electromagnetic Field

2011 ◽  
Vol 402 ◽  
pp. 850-853 ◽  
Author(s):  
Yu Bo Zuo ◽  
Zhi Hao Zhao ◽  
Jian Zhong Cui
Keyword(s):  
Electromagnetic Field ◽  
Grain Refinement ◽  
Low Frequency ◽  
Direct Chill ◽  
Current Intensity ◽  
Field Frequency ◽  
7050 Aluminum Alloy ◽  
Microstructure Effects ◽  
Chill Cast ◽  
Direct Chill Cast

Low frequency electromagnetic casting (LFEC) process was used to make 7050 aluminum alloy 162mm ingots and study its effect on the as-cast microstructure. Effects of electromagnetic field parameters such as frequency and current intensity on microstructures were systemically investigated. The results showed that LFEC has a significant grain refining effect on 7050 alloy. The microstructures of LFEC ingot from the border to the center of the cross section are all equiaxed or nearly equiaxed grains which are much finer and more uniform than those of DC cast ingot. It was also found that electromagnetic field frequency and current intensity play important roles on the microstructure refinement. The discussion was mainly focused on the mechanism of grain refinement by LFEC process.

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