Comparison of Various Models of Supercooled Water-Loss Factor with Experimental Data in the Microwave Range

2019 ◽  
Vol 55 (9) ◽  
pp. 1005-1011
Author(s):  
G. S. Bordonskiy ◽  
A. O. Orlov
Keyword(s):  
Experimental Data ◽  
Water Loss ◽  
Loss Factor ◽  
Supercooled Water ◽  
Microwave Range

scholarly journals Comparison of various models of supercooled water loss factor with experimental data at microwaves

2019 ◽  
pp. 104-112
Author(s):  
G. S. Bordonskiy ◽  
A. O. Orlov
Keyword(s):  
Experimental Data ◽  
Critical Point ◽  
Water Loss ◽  
Loss Factor ◽  
Supercooled Water ◽  
Significant Discrepancy ◽  
Deep Supercooling ◽  
Calculation Results ◽  
Adequate Representation ◽  
Silicate Materials

An improved formula for the supercooled water loss factor at frequencies 10…180 GHz in the temperature range 0 ... –70 °C is presented. The formula based on the experimental data obtained by the authors on measurements of attenuation in the pore water of silicate materials. The formula contains two terms connected the Debye dependence of the loss factor on frequency and temperature, and non-Debye, determined by the influence of the second critical point of water. Comparison of the proposed formula and the model formulas of other authors is carried out. A significant discrepancy between the calculation results (at several times) of the loss factor at frequencies above 100 GHz and temperatures below –30 °C has been founded. The model based on the measurements provides the most adequate representation of the behavior of the loss factor with an error of ~ 30% in the area of deep supercooling of water and in the upper part of the studied frequency band.

Multi-Component Mixture Modeling for the Dielectric Properties of Rubber Wood at Microwave Frequencies

Holzforschung ◽  
1999 ◽  
Vol 53 (6) ◽  
pp. 662-668 ◽  
Author(s):  
K.B. Khalid ◽  
M.F. Kabir ◽  
W. M. Daud ◽  
H.A.A. Sidek
Keyword(s):  
Experimental Data ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Loss Factor ◽  
Dielectric Constants ◽  
Dielectric Loss Factor ◽  
Component Mixture ◽  
Microwave Frequencies ◽  
Conductive Loss ◽  
Rubber Wood

Summary Dielectric properties from 1 to 18 GHz of rubber wood are modeled using generalized mixture equations and also with equations proposed by Weiner, Kraszewski, Looyenga and Landou, Lichtenecker. Dielectric properties were measured with an open-ended coaxial line-sensor in three structural directions longitudinal, radial and tangential and at different moisture contents. The dielectric constants were predicted well by the Weiner model for all structural grain directions and it was found that the degree of binding decreases with increasing frequency. However, the Weiner model cannot be used for predicting the dielectric loss factor at frequencies below 3 GHz. This may be due to the high conductive loss in this frequency region. The lower value of the exponents in generalized mixture equation was found suitable for fitting the experimental data as well as the Kraszewski equation. Values predicted by Lichtenecker equations are in well agreement with the experimental data at higher microwave frequencies. The prediction of dielectric loss factor using Kraszewski, Looyenga equations were not possible at frequencies below 3 GHz since it is dominated by conductive loss. Above 3 GHz, it was well predicted by Kraszewski and Looyenga equations.

scholarly journals Origin of the emergent fragile-to-strong transition in supercooled water

2018 ◽  
Vol 115 (38) ◽  
pp. 9444-9449 ◽  
Author(s):  
Rui Shi ◽  
John Russo ◽  
Hajime Tanaka
Keyword(s):  
Experimental Data ◽  
Glass Transition ◽  
Supercooled Water ◽  
Arrhenius Law ◽  
Widom Line ◽  
Slowing Down ◽  
Strong Transition ◽  
Dynamical Properties ◽  
Water Models ◽  
Insight Into

Liquids can be broadly classified into two categories, fragile and strong ones, depending on how their dynamical properties change with temperature. The dynamics of a strong liquid obey the Arrhenius law, whereas the fragile one displays a super-Arrhenius law, with a much steeper slowing down upon cooling. Recently, however, it was discovered that many materials such as water, oxides, and metals do not obey this simple classification, apparently exhibiting a fragile-to-strong transition far above Tg. Such a transition is particularly well known for water, and it is now regarded as one of water’s most important anomalies. This phenomenon has been attributed to either an unusual glass transition behavior or the crossing of a Widom line emanating from a liquid–liquid critical point. Here by computer simulations of two popular water models and through analyses of experimental data, we show that the emergent fragile-to-strong transition is actually a crossover between two Arrhenius regimes with different activation energies, which can be naturally explained by a two-state description of the dynamics. Our finding provides insight into the fragile-to-strong transition observed in a wide class of materials.

A Research on Loss Factor of Embedded and Co-Cured Composite Damping Structure

2012 ◽  
Vol 487 ◽  
pp. 593-597 ◽  
Author(s):  
Peng Mi ◽  
Sen Liang
Keyword(s):  
Experimental Data ◽  
Energy Method ◽  
Loss Factor ◽  
Strain Energy ◽  
Modal Strain Energy ◽  
Calculating Method ◽  
Modal Strain Energy Method ◽  
Simulation Results ◽  
Strain Energy Method

In this paper, modal strain energy method is employed to calculate the modal loss factor of embedded and co-cured composite damping structure (ECCDS). To illustrate the validity of modeling and calculating method, the simulation results are compared with the experimental data. The effects of thickness, number and location of damping layers on damping performance of ECCDS have also been studied in detail.

The evolution of nasal turbinates and mammalian endothermy

Paleobiology ◽  
1992 ◽  
Vol 18 (1) ◽  
pp. 17-29 ◽  
Author(s):  
Willem J. Hillenius
Keyword(s):  
Experimental Data ◽  
Small Mammals ◽  
Environmental Conditions ◽  
Water Loss ◽  
Data Support ◽  
Ventilation Rates

Complex nasal turbinal bones are associated with reduction of respiratory water loss in desert mammals and have previously been described as an adaptation to xeric conditions. However, complex turbinates are found in virtually all mammals. Experimental data presented here indicate that turbinates also substantially reduce respiratory water loss in five species of small mammals from relatively mesic environments. The data support the conclusion that turbinates did not evolve primarily as an adaptation to particular environmental conditions, but in relation to high ventilation rates, typical of all mammals. Complex turbinates appear to be an ancient attribute of mammals and may have originated among the therapsid ancestors of mammals, in relation to elevated ventilation rates and the evolution of endothermy.

scholarly journals Effect of Ultrasonic Pretreatment on Melon Drying and Computational Fluid Dynamic Modelling of Thermal Profile

2020 ◽  
Vol 58 (4) ◽  
Author(s):  
João Henrique Fernandes da Silva ◽  
José Sabino da Silva Neto ◽  
Edilene Souza da Silva ◽  
Danilo Emídio de Souza Cavalcanti ◽  
Patrícia Moreira Azoubel ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Temperature Profile ◽  
Water Loss ◽  
Ultrasonic Waves ◽  
Drying Time ◽  
Solid Gain ◽  
Drying Kinetic ◽  
Computational Fluid Dynamics Cfd

Research background. Drying is one of the most traditional processes for food preservation. Optimizing the process can result in a competitive product on price and quality to the market. One technology in use as a pretreatment to drying is ultrasound. This work had as the goal to analyze different drying systems with and without applying ultrasound (US) pretreatment, on heat and mass transfer, simulating numerically the temperature profile by computational fluid dynamics (CFD). Experimental approach. The melon slices were pretreated with ultrasound for 10 (US10), 20 (US20), and 30 (US30) min at 25 kHz, and the water loss and solids gain were evaluated. Drying was performed at different temperatures (50, 60, and 70 °C). The effective diffusivity was estimated, and experimental data were modeled using empirical models. The airflow in the dryer and the temperature profile in the melon slice were simulated via computational fluid dynamics (CFD). Results and conclusions. Drying time had a 25 % (US20 and US30 at 50 °C) to 40 % (US20 and US30 at 70 °C) reduction. The Two terms model presented the best fit to the experimental data, and the diffusivity coefficients showed a tendency to increase as the time of exposure of the melon to ultrasonic waves increased. Pretreatment water loss and solid gain behavior and drying kinetic and diffusion data were used to choose the best experimental condition to be simulated with CFD. The heat transfer modelling through CFD showed that the temperature distribution along the melon slice was representative. Therefore, the profile obtained via CFD satisfactorily describes the drying process. Novelty and scientific contribution. The use of simulation tools in real processes allows the monitoring and improvement of existing technologies, such as food drying processes, that involve complex mechanisms, making it difficult to obtain some data. Application of CFD in the drying processes of fruits and vegetables is still very recent, being a field little explored. There is no record in the literature that uses CFD in the drying of melon.

scholarly journals Research of PVDF Energy Harvester Cantilever Parameters for Experimental Model Realization

Electronics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2030
Author(s):  
Mindaugas Cepenas ◽  
Bingzhong Peng ◽  
Darius Andriukaitis ◽  
Chandana Ravikumar ◽  
Vytautas Markevicius ◽  
...  
Keyword(s):  
Experimental Data ◽  
Loss Factor ◽  
Output Voltage ◽  
Energy Harvester ◽  
Electronic Devices ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
True Model ◽  
Potential Applications ◽  
Real Value

Piezoelectric energy harvesters have been extensively researched for use with wireless sensors or low power consumption electronic devices. Most of the piezoelectric energy harvesters cannot generate enough power for potential applications. In this study, we explore the parameters, including gap and proof mass, that can affect the damping of the cantilever to optimize the design of the energy harvester. A finite analysis is conducted using COMSOL Multiphysics software. Usually, this type of simulation is performed using the loss factor. However, it is known that results from the loss factor produce models that do not fit the experimental data well. In fact, the result of output voltage using the loss factor is 50% higher than the real value, which is due to ignoring the adverse effect of a superimposing mechanical damping of different constituent materials. In order to build a true model, Rayleigh damping coefficients are measured to use in a simulation. This resulted in a closer fit of modeling and experimental data, and a 5 times better output voltage from the optimized energy harvester compared with using the smallest gap and mass.

scholarly journals Post-harvest of parsley leaves (Petroselinum crispum): Mathematical modelling of drying and sorption processes

2018 ◽  
Vol 22 (2) ◽  
pp. 131-136 ◽  
Author(s):  
Luiz C. Corrêa Filho ◽  
Ana P. Martinazzo ◽  
Carlos E. de S. Teodoro ◽  
Ednilton T. de Andrade
Keyword(s):  
Experimental Data ◽  
Moisture Content ◽  
Mathematical Modelling ◽  
Mathematical Models ◽  
Water Loss ◽  
Isosteric Heat ◽  
Petroselinum Crispum ◽  
High Consumption ◽  
Desorption Isotherms ◽  
Drying Curves

ABSTRACT Parsley is a species of wide production and trade in Brazil due to its high consumption as a condiment, fresh or dried. In the development of equipment used for drying, it is important to simulate and obtain theoretical information about the behavior of water loss for each product. Given the increasing use and potential commercialization of condimental plants, the objective of this work was to determine the isosteric heat of parsley leaves and fit mathematical models to the experimental data obtained in drying and desorption processes. The modified GAB and Midilli models were the most appropriate to describe the desorption isotherms and drying curves, respectively, for the studied temperatures. The isosteric heat varied from 3394.6 to 2830.0 kJ kg-1 for the equilibrium moisture content in the range from 0.0154 to 3.7232 (d.b.).

Dielectric Properties Measurements and Data

1990 ◽  
Vol 189 ◽  
Author(s):  
Joseph A. Carpenter
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Loss Factor ◽  
Intelligent Design ◽  
Elevated Temperatures ◽  
Measurement Techniques ◽  
Materials Processing ◽  
Microwave Range ◽  
Solid Materials ◽  
Dielectric Constant And Loss

ABSTRACTThis paper reviews measurement techniques and sources of data for the dielectric constant and loss factor of solid materials. Accurate values of such properties are basic to intelligent design of materials processing schemes utilizing electromagnetic energy. Emphasis is on techniques and data for these properties in the “microwave” range of frequencies of roughly 108 to 1011 Hz and at elevated temperatures.

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