Institute of Fundamental Technological Research

At present, the problem of identifying and controlling different types of Mechanically
Separated Meat (MSM) is a very important practical issue in the meat industry. To address this
challenge, the authors propose a new, analytical method for the discrimination and characterization
of MSM that uses density measurements. The method proposed by the authors, in contrast to the analytical methods existing so far, is rapid, non-destructive, relatively simple and can be computerized.
The density measurements of meat samples were conducted with a modified pycnometric method.
Statistically significant (p < 0.01) differences were found in the evaluated mean values of density
for all investigated types of meat. Subsequently, the density measurements were correlated with
the physicochemical properties of meat samples. A high correlation coefficient was found between
the density of meat samples and the content of protein, sodium and fat. The authors have proven
that density measurements allow for rapid discrimination of various types of MSM, and can also be
effectively used to determine the chemical composition of MSM samples, e.g., the content of protein,
fat and sodium.

Meat density; Mechanically Separated Meat (MSM); protein content; fat content; Sodium (Na) content; Calcium content (Ca)

An innovative analytical ultrasonic method for identification and investigation of Mechanically Separated Meat (MSM) samples is presented. To this end, the ultrasonic wave velocity (f = 5 MHz) in the investigated meat samples was measured. The measured ultrasonic velocity ranged from 1553.4 to 1589.9 m/s. The investigations were performed for: 1) minced hand deboned chicken fillets, 2) low pressure MSM from chicken carcasses, 3) low pressure MSM from chicken collarbones, 4) high pressure MSM from chicken carcasses and 5) high pressure MSM from chicken collarbones. Statistically significant (p < 0.001) differences in the ultrasonic velocity were observed for each of investigated kinds of meat. High significant correlations were found between the ultrasonic velocity and the content of protein, fat, sodium and density of the investigated meat. The applicability of the developed ultrasonic method for identifying various kinds of meat and to determine the content of protein, fat, sodium and density was demonstrated.

physicochemical parameters, mechanically separated meat, ultrasonic velocity, protein content, calcium content, fat content

In this work we analyse basic characteristics of Love wave sensors implemented in waveguide structures composed of a lossy viscoelastic surface layer deposited on a lossless elastic substrate. It has to be noted that Love wave sensors working at ultrasonic frequencies have the highest mass density sensitivity S among all known ultrasonic sensors, such as QCM, Lamb wave or Rayleigh wave sensors. In this paper we have established an exact analytical formula for the mass density sensitivity S of the Love wave sensors in the form of an explicit algebraic expression. Subsequently, using this developed analytical formula, we compared theoretically the mass density sensitivity S for various Love wave waveguide structures, such as: (1) lossy PMMA surface layer on lossless Quartz substrate and (2) lossy PMMA on lossless Diamond substrate. The performed analysis shows that the mass density sensitivity S (real and imaginary part) for a sensor with a structure PMMA on Diamond is five times higher than that of a PMMA on Quartz structure. It was found that the mass density sensitivity S for Love wave sensors increases with the increase of the ratio: bulk shear wave velocity in the substrate to bulk shear wave velocity in the surface layer.

Love wave sensors, mass sensitivity, complex dispersion equation, viscoelastic layers

Vapors of benzene and its derivatives are harmful and toxic for human beings and natural environment. Their detection has fundamental importance. For this purpose authors propose surface acoustic wave (SAW) sensor with skeletonized layer deposited by Langmuir-Blodgett (L-B) method. This layer was obtained by depositing a binary equimolar mixture of 5-[[1,3-dioxo-3-[4-(1-oxooctadecyl) phenyl]propyl]amino]–1,3–benzenedicarboxylic acid with cetylamine. The skeletonized sensor layer has been obtained by removing cetylamine. Response of this sensor depends mainly of the electrical dipole momentum of molecule. Among the tested compounds, benzene has a zero dipole moment and gives the smallest sensor response, and nitrobenzene has the largest dipole moment and the sensor reacts most strongly to its vapor.

SAW sensor, Langmuir-Blodget layer, vapors, benzene, benzene derivatives

In this study, we analyze theoretically and numerically the properties of Love surface waves propagating in lossy multilayered composite waveguides, loaded on the upper surface with a Newtonian liquid. The propagation of Love surface waves was formulated in terms of a direct Sturm–Liouville problem. An analytical form of the complex dispersion equation of the Love surface wave was derived using the Thomson–Haskell transfer matrix method. By separating the complex dispersion equation into its real and imaginary parts, we obtained a set of two nonlinear algebraic equations, which were subsequently solved numerically. The effect of various physical parameters of the lossy viscoelastic waveguide on the velocity and attenuation of the Love surface wave was then analyzed numerically. It was found that because of the presence of losses in the analyzed waveguide, Love surface waves displayed a number of new original phenomena, such as resonant-like maxima in attenuation as a function of thicknesses h1 of the first viscoelastic surface layer and thickness h2 of the second elastic surface layer. These phenomena are completely absent in lossless waveguides.

lossy waveguides, nondestructive testing of polymeric layered structures, Love surface waves, viscoelastic materials

In this paper, the authors analyse the propagation of surface Love waves in an elastic layered waveguide (elastic guiding layer deposited on an elastic substrate) covered on its surface with a Newtonian liquid layer of finite thickness. By solving the equations of motion in the constituent regions (elastic substrate, elastic surface layer and Newtonian liquid) and imposing the appropriate boundary conditions, the authors established an analytical form of the complex dispersion equation for Love surface waves. Further, decomposition of the complex dispersion equation into its real and imaginary part, enabled for evaluation of the phase velocity and attenuation dispersion curves of the Love wave. Subsequently, the influence of the finite thickness of a Newtonian liquid on the dispersion curves was evaluated. Theoretical (numerical) analysis shows that when the thickness of the Newtonian liquid layer exceeds approximately four penetration depths 4δ of the wave in a Newtonian liquid, then this Newtonian liquid layer can be regarded as a semi-infinite half-space. The results obtained in this paper can be important in the design and optimization of ultrasonic Love wave sensors such as: biosensors, chemosensors and viscosity sensors. Love wave viscosity sensors can be used to assess the viscosity of various liquids, e.g. liquid polymers.

Love waves, ultrasonic sensors, Newtonian liquid, penetration depth, biosensors, chemosensors, viscosity sensors

An emerging ultrasonic technology aims to control high-pressure industrial processes that use liquids at pressures up to 800 MPa. To control these processes it is necessary to know precisely physicochemical properties of the processed liquid (e.g., Camelina sativa oil) in the high-pressure range. In recent years, Camelina sativa oil gained a significant interest in food and biofuel industries. Unfortunately, only a very few data characterizing the high-pressure behavior of Camelina sativa oil is available. The aim of this paper is to investigate high pressure physicochemical properties of liquids on the example of Camelina sativa oil, using efficient ultrasonic techniques, i.e., speed of sound measurements supported by parallel measurements of density. It is worth noting that conventional low-pressure methods of measuring physicochemical properties of liquids fail at high pressures. The time of flight (TOF) between the two selected ultrasonic impulses was evaluated with a cross-correlation method. TOF measurements enabled for determination of the speed of sound with very high precision (of the order of picoseconds). Ultrasonic velocity and density measurements were performed for pressures 0.1–660 MPa, and temperatures 3–30 °C. Isotherms of acoustic impedance Za, surface tension σ and thermal conductivity k were subsequently evaluated. These physicochemical parameters of Camelina sativa oil are mainly influenced by changes in the pressure p, i.e., they increase about two times when the pressure increases from atmospheric pressure (0.1 MPa) to 660 MPa at 30 °C. The results obtained in this study are novel and can be applied in food,and chemical industries.

ultrasonic methods, speed of sound, acoustic impedance, surface tension, thermal conductivity, physicochemical properties

Modeling of high-pressure technological processes in the food industry requires knowledge of thermophysical parameters of processed foodstuffs in a broad range of pressures and temperatures. However, the high-pressure thermophysical parameters of foodstuffs are very rarely published in the literature. Therefore, further research is necessary to achieve a deeper insight into the biophysical and thermophysical phenomena under pressure to provide better control of technological processes and optimize the effects of pressure. The essential goal of this work is to evaluate the impact of high pressure and temperature on the thermophysical parameters of liquid foodstuffs on the example of diacylglycerol (DAG) oil (which attracted recently a considerable attention from research and industrial communities due to its remarkable benefits for health), using ultrasonic wave velocity and density measurements. Isotherms of adiabatic and isothermal compressibility, isobaric thermal expansion coefficient, internal pressure, and thermal pressure coefficient versus pressure were evaluated, based on the measurement of the compressional ultrasonic wave velocity and density of DAG oil at high pressures (up to 500 MPa) and at various temperatures. The adiabatic compressibility is affected mostly by the changes of pressure, i.e., it grows about four times when the pressure increases from the atmospheric pressure (0.1 MPa) to 400 MPa at a temperature of 50 °C. By contrast, the internal pressure is a pronounced function of the temperature, i.e., it increases six times when the temperature rises from 20 to 50 °C at a pressure of a 200 MPa. To perform numerical calculations, it was convenient to introduce a Tammann–Tait type equation of state to approximate the measured density isotherms of the investigated DAG oil. The results obtained in this paper can be applied in modeling and optimization of high-pressure technological processes and processing of foodstuffs. Evaluation of high-pressure isotherms of the considered thermophysical parameters of the DAG oil is an original authors' contribution to the state-of-the-art.

high-pressure food processing, diacylglycerols, thermophysical parameters, isothermal compressibility, isobaric thermal expansion coefficient, ultrasonic methods

Investigation of the high-pressure thermophysical properties of biofuels, e.g., bulk modulus, Surface tension, and viscosity is of paramount importance in fuel injection systems in diesel engines. Another crucial and dangerous phenomenon that may occur in biofuels at high pressures is phase transition (solidification), which can drastically increase the viscosity of the biofuel. This effect may hamper proper operation of the engine, especially under cold-start conditions. Unfortunately, the availability of highpressure thermophysical properties of biofuels is still limited. The goal of this paper is to investigate the impact of high pressures on thermophysical properties of biofuels on the example of rapeseed fatty acid methyl esters (RME) in a wide range of pressures (0:1 to 250 MPa) and temperatures (5 to 20 _C). To this end we employed innovative ultrasonic techniques, i.e., the Bleustein-Gulyaev surface acoustic waves for measuring RME viscosity, and ultrasonic bulk compressional waves for measuring sound velocity in RME and consequently evaluating RME thermophysical parameters, e.g., bulk modulus and surface tension. The viscosity of the measured RME displayed an abrupt increase at pressures: 260 MPa (t Ľ 20 _C), 230 MPa (t Ľ 15 _C), 190 MPa (t Ľ 10 _C), and 130 MPa (t Ľ 5 _C). Evidently it was a signature of the phase transition (solidification) occurring in the RME. The discovered high viscosity high-pressure phase in RME can be very detrimental for operation of modern common rail Diesel engines. Therefore, the results of research presented in this paper should be interesting for engineers and designers working with modern common rail Diesel engines using biofuels.

Biofuels, Methyl esters, Phase transitions, Viscosity, Speed of sound, Ultrasonic methods, High pressure

This paper presents a theoretical study of the propagation behavior of ultrasonic Love waves in nonhomogeneous functionally graded elastic materials, which is a vital problem in the mechanics of solids. The elastic properties (shear modulus) of a semi-infinite elastic half-space vary monotonically with the depth (distance from the surface of the material). The Direct Sturm–Liouville Problem that describes the propagation of Love waves in nonhomogeneous elastic functionally graded materials is formulated and solved by using two methods: i.e., (1) Finite Difference Method, and (2) Haskell-Thompson Transfer Matrix Method.

The dispersion curves of phase and group velocity of surface Love waves in inhomogeneous elastic graded materials are evaluated. The integral formula for the group velocity of Love waves in nonhomogeneous elastic graded materials has been established. The effect of elastic non-homogeneities on the dispersion curves of Love waves is discussed. Two Love wave waveguide structures are analyzed: (1) a nonhomogeneous elastic surface layer deposited on a homogeneous elastic substrate, and (2) a semi-infinite nonhomogeneous elastic half-space. Obtained in this work, the phase and group velocity dispersion curves of Love waves propagating in the considered nonhomogeneous elastic waveguides have not previously been reported in the scientific literature. The results of this paper may give a deeper insight into the nature of Love waves propagation in elastic nonhomogeneous functionally graded materials, and can provide theoretical guidance for the design and optimization of Love wave based devices.

Ultrasonic Love waves, Functionally graded materials, Profiles of elastic constants, Direct Sturm–Liouville Problem, Group velocity

This paper presents the use of SH (Shear Horizontal) surface Love waves to determine the distributions of elastic parameters in nonhomogeneous Functionally Graded Materials. The advantage of Love waves applied to investigate the elastic properties of materials is that the Love wave energy (in contrast to the other types of waves, e.g., plate Lamb waves) is concentrated in the vicinity of the surface layer. The penetration depth of the SH surface Love waves depends on the frequency. Therefore, Love waves are particularly suitable for investigating the profiles of the mechanical properties in nonhomogeneous Graded Materials. Direct Problem (Direct Sturm-Liouville Problem) that describes the propagation of Love waves in nonhomogeneous graded materials has been formulated and solved numerically by applying the Transfer Matrix Method. The Inverse Procedure (Inverse Sturm-Liouville Problem) for determining the distribution of elastic properties versus depth in the nonhomogeneous materials has been developed. Love wave dispersion curves in nonhomogeneous graded materials were evaluated numerically (synthetic data). Using the evaluated dispersion curves of Love waves and a developed Inverse Procedure the distributions of elastic shear coefficient as a function of depth (distance from the surface of the material into the bulk) in a heterogeneous surface layer deposited on a homogeneous substrate have been evaluated. Power type profiles (i.e., root square, linear and quadratic) of the shear elastic coefficient in the surface layer were considered. The results of this study can be useful in the investigation of elastic properties of Graded Materials in electronics as well as in geophysics and seismology.

Love waves, Inverse Methods, Functionally Graded Materials, Elastic parameters, Sturm-Liouville Problem

In many technological processes (e.g., in the chemical, petrochemical, food, and plastics industries), liquids are subjected to high pressures and temperatures. Therefore, knowledge of their thermodynamic properties is essential for understanding, design, and control of the process technology. Direct evaluation of the thermodynamic parameters of liquids under high pressure, using conventional methods, is very difficult. Therefore, the application of these methods in industrial conditions, particularly in on-line control of the technological parameters of liquids, is practically impossible. Ultrasonic methods (e.g., sound speed measurements) are very suitable for this purpose because of their simplicity and accuracy. The sound velocity is closely related to numerous thermodynamic properties of liquids. The objective of this paper is to address the influence of temperature and pressure on the thermodynamic parameters of liquids, using the example of diacylglycerol (DAG) oil, employing ultrasonic methods. In this paper, we present ultrasonic velocity and density measurements (performed by the authors) in DAG oil over a range of pressures and temperatures. On the basis of experimental results (the sound velocity and liquid density versus pressure and temperature) a series of DAG oil thermodynamic parameters such as specific heat ratio, intermolecular free path length, Van der Waals constant b, surface tension, and effective Debye temperature were evaluated as functions of pressure and temperature.

Thermodynamical properties of liquid, High pressure food processing, ultrasonic methods, sound velocity, surface tension

This paper presents a theoretical study of the propagation behaviour of surface Love waves in nonhomogeneous functionally graded elastic materials, which is a vital problem in acoustics. The elastic properties (shear modulus) of a semi-infinite elastic half-space vary monotonically with the depth (distance from the surface of the material). Two Love wave waveguide structures are analyzed: 1) a nonhomogeneous elastic surface layer deposited on a homogeneous elastic substrate, and 2) a semi-infinite nonhomogeneous elastic half-space. The Direct Sturm-Liouville Problem that describes the propagation of Love waves in nonhomogeneous elastic functionally graded materials is formulated and solved 1) analytically in the case of the step profile, exponential profile and 1cosh2 type profile, and 2) numerically in the case of the power type profiles (i.e. linear and quadratic), by using two numerical methods: i.e. a) Finite Difference Method, and b) Haskell-Thompson Transfer Matrix Method.

The dispersion curves of phase and group velocity of surface Love waves in inhomogeneous elastic graded materials are evaluated. The integral formula for the group velocity of Love waves in nonhomogeneous elastic graded materials has been established. The results obtained in this paper can give a deeper insight into the nature of Love waves propagation in elastic nonhomogeneous functionally graded materials.

surface Love waves, group velocity, phase velocity, functionally graded materials, profiles of elastic constants, direct Sturm-Liouville problem

High-pressure processing is a powerful technology for food preservation. The knowledge of foods properties in the high-pressure range is important to develop and optimize such processes by means of mathematical modeling and simulation. Ultrasonic methods are rapid, non-invasive and can be used to characterize foods like edible oils (e.g., composition, purity, and quality assessment). In this paper, they were applied for the investigation of physicochemical properties of olive oil at high pressure at different temperatures. The sound wave velocity was measured by the pulse-transmission method and the corresponding oil density was additionally determined from the monitoring of sample volume change. Measurements were conducted in the pressure range up to 600 MPa, for temperatures from 20 to 50°C. Intermolecular free length, isothermal and adiabatic compressibility versus pressure were calculated using measured sound speed and density isotherms. Discontinuities in the measured isotherms of sound speed and density versus pressure indicate the presence of liquid-to-solid phase transitions. The kinetics of the liquid-to-solid phase transition was also investigated. The transformation times of olive oil augment with increasing temperature. This study can be broadened to other liquid foodstuffs to investigate the influence of temperature on their physicochemical properties at high pressure.

Physicochemical properties, Intermolecular free length, Ultrasonic velocity, High-pressure food processing, Olive oils

Simultaneous determination of the viscosity and density of liquids is of great importance in the monitoring of technological processes in the chemical, petroleum, and pharmaceutical industry, as well as in geophysics. In this paper, the authors present the application of Love waves for simultaneous inverse determination of the viscosity and density of liquids. The inversion procedure is based on measurements of the dispersion curves of phase velocity and attenuation of ultrasonic Love waves. The direct problem of the Love wave propagation in a layered waveguide covered by a viscous liquid was formulated and solved. Love waves propagate in an elastic layered waveguide covered on its surface with a viscous (Newtonian) liquid. The inverse problem is formulated as an optimization problem with appropriately constructed objective function that depends on the material properties of an elastic waveguide of the Love wave, material parameters of a liquid (i.e., viscosity and density), and the experimental data. The results of numerical calculations show that Love waves can be efficiently applied to determine simultaneously the physical properties of liquids (i.e., viscosity and density). Sensors based on this method can be very attractive for industrial applications to monitor on-line the parameters (density and viscosity) of process liquid during the course of technological processes, e.g., in polymer industry.

Viscosity, Inverse problems, Wave attenuation, Mechanical waves, Viscosity measurements

The purpose of the paper is to address, using ultrasonic methods, the impact of temperature and pressure on the physicochemical properties of liquids on the example of diacylglycerol (DAG) oil. The paper presents measurements of sound velocity, density and volume of DAG oil sample in the pressure range from atmospheric pressure up to 0.6 GPa and at temperatures ranging from 20 to 50°C.

Sound speed measurements were performed in an ultrasonic setup with a DAG oil sample located in the high-pressure chamber. An ultrasonic method that uses cross-correlation method to determine the time-of-flight of the ultrasonic pulses through the liquid was employed to measure the sound velocity in DAG oil. This method is fast and reliable tool for measuring sound velocity. The DAG oil density at high pressure was determined from the monitoring of sample volume change. The adiabatic compressibility and isothermal compressibility have been calculated on the basis of experimental data. Discontinuities in isotherms of the sound speed versus pressure point to the existence of phase transitions in DAG oil. The ultrasonic method presented in this study can be applied to investigate the physicochemical parameters of other liquids not only edible oils.

Ultrasonic methods, Sound velocity, Phase transitions, High pressure food processing, Physicochemical parameters

The paper presents a new electromechanical amplifying device i.e., an electromechanical biological transistor. This device is located in the outer hair cell (OHC), and constitutes a part of the Cochlear amplifier. The physical principle of operation of this new amplifying device is based on the phenomenon of forward mechanoelectrical transduction that occurs in the OHC's stereocilia. Operation of this device is similar to that of classical electronic Field Effect Transistor (FET). In the considered electromechanical transistor the input signal is a mechanical (acoustic) signal. Whereas the output signal is an electric signal. It has been shown that the proposed electromechanical transistor can play a role of the active electromechanical controlled element that has the ability to amplify the power of input AC signals. The power required to amplify the input signals is extracted from a battery of DC voltage. In the considered electromechanical transistor, that operates in the amplifier circuit, mechanical input signal controls the flow of electric energy in the output circuit, from a battery of DC voltage to the load resistance. Small signal equivalent electrical circuit of the electromechanical transistor is developed. Numerical values of the electrical parameters of the equivalent circuit were evaluated. The range, which covers the levels of input signals (force and velocity) and output signals (voltage, current) was determined. The obtained data are consistent with physiological data. Exemplary numerical values of currents, voltages, forces, vibrational velocities and power gain (for the assumed input power levels below 1 picowatt (10-12 W)), were given. This new electromechanical active device (transistor) can be responsible for power amplification in the cochlear amplifier in the inner ear.

cochlear amplifier, acoustoelectric transducers, electromechanical transistor, equivalent circuits, field effect transistors, ion currents

The nonlinearity parameter B/A is a measure of the nonlinearity of the equation of state for a fluid. The nonlinearity parameter B/A is a physical parameter often used in acoustics, from underwater acoustics to biology and medicine. It can provide information about structural properties of the medium, internal pressure and inter-molecular spacing. The thermodynamic method has been applied for determination of B/A parameter in diacylglycerol (DAG) oil as a function of pressure at various temperatures. Isotherms of the density and phase velocity of longitudinal ultrasonic wave as a function of pressure have been measured. Using the thermo- dynamic method along with measured isotherms of sound speed and density, the nonlinearity parameter B/A (for DAG oil) was evaluated as a function of pressure (up to 220 MPa) at various temperatures ranging from 20 to 50◦C.

Nonlinearity parameter B/A, thermodynamic method, high pressure, longitudinal ultrasonic wave velocity

This paper presents measurements of sound velocity and attenuation in olive oil, with known chemical composition, as a function of pressure, within the range of pressure up to 0.7 GPa. Dependencies of sound velocity, relative ultrasonic wave attenuation, volume, and adiabatic compressibility on pressure show discontinuities. This proves the existence of the first order phase transition in olive oil (liquid to solid-like phase transition). Rapid and large changes in relative attenuation testify to the existence of a phase transition in olive oil. Moreover, the kinetics of phase transition was also investigated. Measurement of acoustic wave velocity and relative attenuation in olive oil during the phase transition and in the high-pressure phase is a novelty. The results obtained can be useful in the development of new methods in food (edible oils) control, processing, and preservation.

Vegetable oils, Sound velocity, Triacylglycerols, Phase transition, High pressure

In this article, the influence of high pressure on sound velocity at 293 K has been presented. The investigated diacylglycerol oil (DAG – [D82T18]AG) was composed of 82% DAGs and 18% triacylglycerols. The variation of sound velocity with hydrostatic pressure for DAG was evaluated up to 400 MPa. The phase transformation in DAG has been observed as a discontinuity of the dependence of sound velocity on pressure. The sound velocity during the phase transition has shown distinct increment. Also the volume changes have been measured. It has shown the rapid drop of the volume at the phase transformation pressure due to the possible crystallization of DAG oil.

high pressure, velocity, DAG

The influence of high pressure on viscosity and compressibility of diacylglycerol (DAG) oil has been presented in this paper. The investigated DAG oil was composed of 82% of DAGs and 18% TAGs (triacylglycerols). The dynamic viscosity of DAG was investigated as a function of the pressure up to 400 MPa. The viscosity was measured by means of the surface acoustic wave method, where the acoustic waveguides were used as sensing elements. As the pressure was rising, the larger ultrasonic wave attenuation was observed, whereas amplitude decreased with the liquid viscosity augmentation. Measured changes of physical properties were most significant in the pressure range near the phase transition. Deeper understanding of DAG viscosity and compressibility changes versus pressure could shed more light on thermodynamic properties of edible oils.

DAG viscosity, compressibility, phase transitions, transmitted and scattered light

The main interest of pharmacokinetics is the study of the fate of drugs in the living organism. This work proposes the system of the conservation laws that describes time-dependent concentrations of a drug, after a single intravenous administration. Compared with others, the proposed model considers both free and protein-bound drug concentrations at the same time. Plasma protein binding captured in the model enters the nonlinearity arising from the Guldberg-Waage law. According to our best knowledge, the analytical solution for our system does not exist. Our model allows the calculation of the free and bound-drug protein concentrations at any time point and at any dose after single intravenous bolus dose administration. In order to compare the empirical with simulated data, a numerical approach has been proposed. On the basis of published experimental data the model validation has been carried out. The goodness of fit was satisfactory (R2 = 0.99) and the experimental and simulated AUC (area under the curve) values, as the measure of the bioavailability of drug, were similar (150 M/hxh−1). The preliminary assessment of the model credibility was positive and encouraged further studies.

Evolution equations, non-linear model, drug protein binding

In this paper, phase transitions in diacylglycerol (DAG) oil are investigated by using an ultrasonic method for measuring viscosity. Viscosity of diacylglycerol (DAG) oil is measured over a wide range of hydrostatic pressures up to 500 MPa, and at temperatures ranging from 10 to 40 °C. The observed discontinuities in the viscosity versus pressure curves (isotherms) indicate phase transitions. An original ultrasonic method that uses the surface acoustic Bleustein–Gulyaev (B–G) wave was employed to measure the viscosity of DAG oil at high pressure range. This method allows for fast and reliable measurement of DAG oil viscosity along various isotherms. Moreover, the kinetics of the observed phase transformations at various temperatures was analyzed. The results of the study are a novelty, and can be helpful in evaluating the physicochemical properties of edible oils.

Edible oils, Ultrasonic methods, Diacylglycerols, Viscosity, Phase transitions, High pressure

This paper describes a theory of surface Love waves propagating in a layered elastic waveguide loaded on its surface by a viscous (Newtonian) liquid. An analytical expression for the complex dispersion equation of Love waves has been established. The real and imaginary parts of the complex dispersion equation were separated and resulting system of nonlinear algebraic equations was solved numerically. The influence of the viscosity of liquid on the dispersion curves of phase velocity, the wave attenuation and the distribution of the Love wave amplitude is analyzed numerically. The propagation loss is produced only by the viscosity of liquids. Elastic layered waveguide is assumed to be loss-less. The numerical solutions show the dependence of the phase velocity change, the wave attenuation and the wave amplitude distribution in terms of the liquid viscosity and the wave frequency. The results of the investigations are fundamental and can be applied in the design and development of liquid viscosity sensors and biosensors, in Non-Destructive Testing (NDT) of materials, in geophysics and seismology.

Love waves, Viscous liquids, Dispersion relations, Attenuation, Viscosity sensors

In this work, the variation of sound velocity with hydrostatic pressure for oleic acid is evaluated up to 350MPa. During the measurement, we identified the phase transformation of oleic acid and the presence of the hysteresis of the dependence of sound velocity on pressure. From the performed measurements, it can be seen that the dependence of sound velocity on pressure can be used to investigate phase transformations in natural oils. Ultrasonic waves were excited and detected using piezoelectric LiNbO3(Y-36 cut) 5MHz transducers. The phase velocity of the longitudinal ultrasonicwaveswas measured using a cross-correlation method to evaluate the time of flight.

Sound velocity, oleic acid, high pressure, phase transition

Viscosity measurements were carried out on triolein at pressures from atmospheric up to 650 MPa and in the temperature range from 10 C to 40 C using ultrasonic measuring setup. Bleustein–Gulyaev SH surface acoustic waves waveguides were used as viscosity sensors. Additionally, pressure changes occurring during phase transition have been measured over the same temperature range. Application of ultrasonic SH surface acoustic waves in the liquid viscosity measurements at high pressure has many advantages. It enables viscosity measurement during phase transitions and in the high-pressure range where the classical viscosity measurement methods cannot operate. Measurements of phase transition kinetics and viscosity of liquids at high pressures and various temperatures (isotherms) is a novelty. The knowledge of changes in viscosity in function of pressure and temperature can help to obtain a deeper insight into thermodynamic properties of liquids.

SH surface acoustic waves, Viscosity, High pressure, Phase transitions

Estimation of the mechanical and geometrical parameters of thin coatings and surface layers in materials is of great practical importance in engineering and technology. Indeed, surface properties of many vital engineering components, such as turbine blades, pistons, or bearings, directly affect longevity and safety of the modern machinery. In this article, the authors present a novel inversion procedure for simultaneous determination of thickness, shear elastic constant, and density of thin coating layers in materials. The inversion procedure is based on measurements of the dispersion curve for surface acoustic waves of the Love type. The inverse problem is formulated as an optimization problem with the appropriately designed objective function, depending on the material parameters of the coating layer, ultrasonic frequency, and the experimental data, i.e. measured phase velocity of the surface Love wave. The minimization of the objective function provides three parameters of a thin layer, i.e. its thickness, shear elastic constant, and density. The proposed inverse method was checked experimentally for different layered structures, such as copper layer on steel substrate or ceramics-on-ceramics. The agreement between the results of calculations with the proposed inversion method and the experimental data was good.

Inverse problems, Love surface waves, elastic constants, acoustic wave dispersion, thin layers

A new ultrasonic method of viscosity measurement at a high-pressure condition has been presented. The method is based on the Love wave amplitude measurement. The same electronic setup as in the Bleustein– Gulyaev (B–G)wave method applied by the authors recently for a high-pressure measurementwas adopted. The new transducers were made of metallic materials which make them more reliable at high-pressure conditions. The method has been successfully applied for the viscosity measurement of some triglycerides at high-pressure conditions up to 1GPa. The results have been compared with the earlier results obtained using B–G waves. This comparison has shown that Love wave method sensors are more reliable than B–G wave sensors and cheaper in fabrication, although the sensitivity of Love wave sensors was lower. During the measurement, the phase transitions in the investigated liquids were observed.

Love SH waves, viscosity, phase transitions, sensors

The elastic properties of coatings and graded materials are very important in the design and evaluation for engineering purposes. It is well known that the velocity of the ultrasonic surface waves propagating in the layered structures and graded materials is strongly dependent on the elastic properties of the medium. Thus, by using an appropriate inverse algorithm, the elastic properties can be deduced from the measured phase velocity dispersion curves (dependence of velocity on frequency) of the surface wave.
In this study we applied generalized shear surface waves (i.e., generalized Love waves) to investigate the elastic parameters of the layered media and graded materials. Generalized Love waves posses only one component of the mechanical displacement what is an advantage. Due to this reason, the mathematical description of the propagation of generalized Love waves is simpler than that using Rayleigh waves.
In this article an inversion procedure for determining the elastic and geometrical parameters of thin coating layers from the measured dispersion curves of ultrasonic shear surface waves (i.e., Love waves) is presented. The inverse problem is formulated as an optimization problem with appropriately developed objective function. The objective function depends on the material parameters of the coating layer, frequency, and experimental data (phase velocity of the surface Love wave). The minimization of the objective function leads to a set of the optimum mechanical parameters of the thin layers (e.g., thickness, shear elastic constants). Good conformity between the experimental dispersion curves and those resulting from the inverse method can prove the correctness of the proposed inverse procedure.

Inverse Problems, Love waves, elastic constants, acoustic dispersion, thin layers, graded materials

In this paper, a new method for measuring the viscosity of liquids at high pressure is presented. To this end the authors have applied an ultrasonic method using the Bleustein-Gulyaev (BG) surface acoustic wave. By applying the perturbation method, we can prove that the change in the complex propagation constant of the BG wave produced by the layer of liquid loading the waveguide surface is proportional to the shear mechanical impedance of the liquid. In the article, a measuring setup employing the BG wave for the purpose of measuring the viscosity of liquids at high pressure (up to 1 GPa) is presented. The results of high-pressure viscosity measurements of triolein and castor oil are also presented. In this paper the model of a Newtonian liquid was applied. Using this new method it is also possible to measure the viscosity of liquids during the phase transition and during the decompression process hysteresis of the dependence of viscosity on pressure.

Bleustein-Gulyaev (B-G) waves, high pressure, viscosity measurements, phase transitions

The electro-elastic behavior of a viscoelastically loaded layered cylindrical resonator (sensor) comprising two coupled hollow cylinders is presented. The inner cylinder is a piezoelectric ceramic tube. The outer cylinder is a non-piezoelectric (passive) metallic cylinder. An analytical formula for the electrical admittance of a compound layered cylindrical resonator loaded with a viscoelastic liquid is established. Admittance (conductance) diagrams were obtained using a continuum electromechanical model. The established analytical formulas enable the determination of the influence of the liquid viscosity, material, and geometrical parameters of a compound cylindrical resonator on the response characteristics of the compound sensor. In the paper, the sensor implications resulting from the performed analysis are described. Moreover, the algorithm of the method developed by the authors to evaluate the rheological parameters of a viscoelastic liquid is presented. Good agreement between the theoretical results and experimental data is shown. The analysis presented in this paper can be utilized for the design and construction of cylindrical piezoelectric viscosity sensors, annular accelerometers, filters, transducers, and multilayer resonators.

Compound piezoelectric resonators, admittance diagrams, viscosity measurements, sensors of rheological parameters

In this work we analyze basic characteristics of Love wave sensors implemented in waveguide structures composed of a lossy viscoelastic surface layer deposited on a lossless elastic substrate. It has to be noted that Love wave sensors working at ultrasonic frequencies have the highest mass density sensitivity S_σ^(v_p ) among all known ultrasonic sensors, such as QCM, Lamb wave or Rayleigh wave sensors. In this paper we have established an exact analytical formula for the mass density sensitivity S_σ^(v_p ) of the Love wave sensors in the form of an explicit algebraic expression. Subsequently, using this developed analytical formula, we compared theoretically the mass density sensitivity S_σ^(v_p ) for various Love wave waveguide structures, such as: (1) lossy PMMA surface layer on lossless Quartz substrate and (2) lossy PMMA on lossless Diamond. The performed analysis shows that the mass density sensitivity S_σ^(v_p ) for a sensor with a structure PMMA on Diamond is four times higher than that of a PMMA on Quartz structure. It was found that the mass density sensitivity S_σ^(v_p ) for Love wave sensors increases with the increase of the ratio: bulk shear wave velocity in the substrate to bulk shear wave velocity in the surface layer.

love waves, mass sensitivity, dispersion equation, viscoelastic layers

In many technological processes liquids are subjected to high pressures (up to 800 MPa), e.g., in high pressure preservation of liquid foodstuffs. Similarly, in modern fuel injection systems for diesel engines, biofuels are subjected to pressures up to 300 MPa. In such severe conditions, thermophysical properties of liquid change considerably. Conventional methods for measuring thermophysical properties of liquids completely fail at high pressure conditions. Hence, these methods are of no use in real industrial conditions, during on-line monitoring of industrial processes. Thus, there exist a strong demand for industrial grade measurements methods, which can be used to monitor on-line the actual parameters of liquids. A very promising solution is offered by ultrasonic techniques which are particularly suitable for measurements of thermophysical properties of liquids at high pressures. In addition, the ultrasonic methods (that use low-intensity ultrasonic waves) are totally non-destructive and can be fully automated in real time.

ultrasonic methods, thermophysical properties, high pressure, acoustic impedance, thermal conductivity

In many industrial technological processes, liquids are subjected to high pressures, e.g., in the high pressure food preservation. Similarly, in modern fuel injection systems for diesel engines, biofuel is subjected to a pressure up to 300 MPa. In such conditions, in liquids, high-pressure phase transitions (solidification) can occur that substantially increase the density and liquid viscosity. This solidification can result in significant problems with engine failure under cold-start conditions. This is an evident recipe for disaster, since the engine and its accessories would be very likely quickly destroyed. Thus, it is important to determine at what pressures and temperatures phase transitions occur. Conventional mechanical methods for measuring physicochemical properties of liquids at these extreme conditions do not operate. By contrast, ultrasonic techniques are very suitable for measurements of hysicochemical properties of liquids at high pressure, since they are non-destructive, can be fully automated and are characterized by the absence of moving parts. The aim of this work is to study the high-pressure hysicochemical properties of liquids (exemplified by a Camelina sativa - false flax oil) using novel ultrasonic methods.

pressure, ultrasonic methods, phase transitions, Camelina sativa

Progress in materials science has led to development of new materials with improved functional characteristics. One of the new types of materials introduced into industrial practice are plastics and polymers. These materials exhibit rheological (viscoelastic) properties, which combine simultaneously the properties of liquids and solids. Due to their attractive features, such as low specific weight, high resistance to chemical agents, ease of processing, cost ffectiveness etc. these materials are widely used in chemical, automotive, aviation and space industry. In addition, these materials are very common in many aspects of everyday life. Thus, it is very important, both from the theoretical and practical point of view, to develop new, robust and accurate methods to measure the rheological parameters (viscosity η, elasticity μ and density ρ) of plastics and polymers. The conventional mechanical methods used so far to this end are outdated, time consuming, and cumbersome. Ultrasonic methods do not possess these disadvantages. The first step in the formulation of the Inverse Method for evaluating the rheological parameters of viscoelastic liquids is to formulate and solve the Direct Sturm-Liouville Problem for Love waves propagating in the investigated layered elastic aveguide loaded on its surface with various types of viscoelastic materials (e.g., liquids). The aim of this study is to develop a rigorous mathematical model (Direct Sturm-Liouville Problem) of propagation of shear horizontal (SH) surface Love waves in layered viscoelastic structures, i.e., in layered elastic waveguides with a guiding surface layer covered with a viscoelastic material described by Kelvin-Voigt, Newton and Maxwell viscoelastic models respectively

Love waves, viscoelastic liquid, Sturm-Liouville problem, dispersion curves

Simultaneous determination of the rheological parameters of viscoelastic surface layers is very important in many applications such as: sensors, geophysics, seismology, and in the NDT of materials. Love wave energy is concentrated near the waveguide surface, so that Love waves are especially suited to study the material properties of surface layers. In this work, the Direct Sturm-Liouville Problem for the Love wave propagation in a layered viscoelastic waveguide have been presented and solved. Next, the Inverse Problem was created and solved as an Optimization Problem. The adequately formulated objective function that depends on the elastic and viscoelastic parameters of a waveguide of the Love wave and the experimental data was used. The solution of the Inverse Problem allows to determine unknown values of the viscosity and shear elasticity of a viscoelastic medium from measurements of the dispersion curves of Love waves.

Love waves, rheological properties, viscoelastic materials, inverse problems, viscosity, shear elasticity

The fundamental goal of this work is to verify the hypothesis of the existence of high-pressure phase transitions in biofuel components on the example of rapeseed fatty acid methyl esters (RME), by using ultrasonic methods. in a wide range of pressures (from atmospheric pressure to 300 MPa) and for various temperatures from 5 to 20 °C. Investigation of phase transitions in biofuels at high pressures is of great importance in the design of injection systems in modern diesel engines (common rail). Direct examination of phase transitions in liquids under high pressure, using classical methods, is very difficult. To overcome this disadvantage, the authors applied ultrasonic methods (viscosity measurement), which in contrast to the classical methods allow in a relatively simple way the investigation of high-pressure properties of liquids. Viscosity was measured by the original method that uses ultrasonic surface waves of the Bleustein-Gulyaev type, developed by the authors at the Institute of Fundamental Technological Research in Warsaw. From the measured viscosity isotherms, the occurrence of high-pressure phase transitions in methyl esters were evaluated.

high-pressure phase transitions, biofuels, ultrasonic Bleustein-Gulyaev waves, viscosity measurements

The aim of this study was to evaluate the inverse procedure to determine profiles (as a function of depth) of the mechanical properties of inhomogeneous FGM resulting from the application of various technological processes of surface treatment. First, the Direct Sturm-Liouville Problem for Love waves propagating in elastic graded materials with various profiles of the shear stiffness as a function of the distance from the surface, has been solved using the Finite Difference Method and Transfer Matrix Method (Haskell-Thompson method). Love wave dispersion curves were evaluated in the frequency range from 4 to 23 MHz. The Inverse Problem was formulated as an Optimization Problem with appropriately constructed objective function that depended on the material properties of an elastic waveguide of the Love wave and the experimental data. To minimize the considered objective function, optimization procedures of the Nelder-Mead type from Scilab software package were employed.

Love waves, Inverse Methods, Functionally Graded Materials, Elastic parameters, Sturm-Liouville Problem

The aim of the study was to investigate the phase transitions in biofuel components by using ultrasonic methods on the example of methyl esters of fatty acids, in a wide range of pressures (from atmospheric pressure to 400 MPa) and for various temperatures from 5 to 20 °C. Investigation of phase transitions in biofuels at high pressures is of great importance in the design of injection systems in modern diesel engines (common rail). Direct examination of phase transitions in liquids under high pressure, using classical methods, is very difficult. To overcome this disadvantage, the authors applied ultrasonic methods (viscosity measurement), which in contrast to the classical methods allow in a relatively simple way the investigation high-pressure properties of liquids. Viscosity was measured by the original method that uses ultrasonic surface waves of the Bleustein-Gulyaev type, developed by the authors at the Institute of Fundamental Technological Research in Warsaw. From the measured viscosity isotherms, the occurrence and kinetics of high-pressure phase transitions in methyl esters were evaluated.

High pressure phase transitions, physicochemical parameters of biofuels, ultrasonic viscosity measurements, rapeseed methyl esters

The aim of this work was to establish an inversion procedure for the simultaneous determination of the viscosity and density of liquids. To this end, measurements of dispersion curves of the phase velocity and attenuation of shear horizontal Love waves were applied. Love waves propagate in an elastic layered waveguide covered on its surface with an investigated viscous (Newtonian) liquid. Firstly, the Direct Sturm-Liouville Problem of the Love wave propagation in a such waveguide was formulated and solved. Subsequently, the Inverse Problem was formulated and solved as an Optimization Problem. The appropriately constructed objective function that depends on the material properties of a waveguide of the Love wave, material properties of an investigated liquid (viscosity and density), and the experimental data was employed. The simultaneous determination of both liquid density and viscosity is important in the monitoring of technological processes in many industries (e.g. chemical, petroleum, pharmaceutical industry) as well as in geophysics.

Love waves, Inverse Methods, Density, Viscosity of liquids, Sturm-Liouville Problem

In many technological processes (e.g. in chemical, petrochemical, food and plastics industry) liquids are subjected to high pressures and temperatures. Therefore knowledge of their thermodynamic properties is essential for understanding, design and control of the process technology. Direct evaluation of thermodynamic parameters of liquids under high pressure, using conventional methods, is very difficult. Therefore, these methods are useless in industrial conditions, particularly in on-line control of the technological parameters of liquids. Ultrasonic methods (e.g., sound speed measurements) due to their simplicity and accuracy are very suitable for this purpose. The sound velocity is closely related with numerous thermodynamic properties of liquids. In this paper we report ultrasonic velocity and density measurements (performed by the authors) in diacylglycerol (DAG) oil over a range of pressures and temperatures. On the basis of experimental results (the sound velocity and liquid density versus pressure and temperature) the thermal expansion coefficient, specific heat capacity at constant pressure, isothermal and adiabatic compressibility of DAG oil were calculated as a function of pressure and temperature.

Themodynamic parameters of liquids, high pressure, ultrasonic velocity, density, compressibility

The nonlinearity parameter B/A is a measure of the nonlinearity of the equation of state for a fluid. It plays a significant role in acoustics, from underwater acoustics to biology and medicine. The nonlinearity parameter is important because it determines distortion of a finite amplitude wave propagating in the fluid. Moreover, it can be related to the molecular dynamics of the medium and it can to provide information about structural properties of medium, internal pressures, clustering, intermolecular spacing, etc. Importance of the B/A parameter increases with the development of high-pressure technologies. The thermodynamic method has been applied for determination of B/A parameter in diacylglycerol (DAG) oil as a function of pressure at various temperatures.

Nonlinearity parameter B/A, Thermodynamic method, ultrasoniv velocity, high pressure,

High pressure research of the physicochemical properties of liquids has been stimulated by the fast development of such technologies as biodiesel production, high-pressure food processing and conservation, modification of biotechnological properties. Monitoring and studying liquid viscosity and ultrasonic wave velocity in liquids as a function of pressure and temperature enable to evaluate many important physicochemical parameters of liquids. These methods allow also insight into the phenomena governing the microstructural modifications occurring in treated substances, i.e. phase transitions. The knowledge of physicochemical properties (e.g. density, relaxation time, internal pressure or free volume) of pressurized substances is essential for understanding, design and control of the process technology. Measurements were conducted on the example of diacylglycerol oil (DAG oil), that is an important constituent of oils and fats.

Physicochemical parameters of liquids, high pressure, ultrasonic velocity, viscosity of liquids, DAG oil

Phase transitions in diacylglycerol (DAG) oil were investigated by using an ultrasonic method for measuring viscosity. Viscosity of DAG oil was measured over a wide range of hydrostatic pressures up to 500 MPa, and at temperatures ranging from 10 to 40 °C. The observed discontinuities in the viscosity versus pressure curves (isotherms) indicate phase transitions. An original ultrasonic method that uses the surface acoustic Bleustein-Gulyaev (B-G) wave was employed to measure the viscosity of DAG oil at high pressure range. This method allowed for fast and reliable measurement of DAG oil viscosity along various isotherms. Moreover, the kinetics of the observed phase transformations at various temperatures was analyzed.

Viscosity, Temperature measurement, Ultrasonic variables measurement, Acoustics, Pressure measurement, Acoustic measurements, Liquids

The problem of propagation of Love waves in elastic waveguides loaded on the surface by a viscous (Newtonian) liquid is important in many applications such as geophysics, seismology, investigation of the physical properties of liquids. Love wave energy is concentrated near the waveguide surface, so that Love waves are especially suited to study the material properties of surface layers. In this work, the direct problem and the inverse problem of the Love wave propagation in a layered elastic waveguides loaded with a viscous liquid have been formulated and solved. The inverse problem relies on the determination of the material parameters (e.g., the unknown value of liquid viscosity) from measurements of the dispersion curves of Love waves.

Liquids, Viscosity, Inverse problems, Surface waves, Dispersion, Linear programming, Liquid waveguides

Triolein viscosity was measured at pressures from atmospheric up to 650 MPa and in the temperature range from 10° C to 40° C using ultrasonic measuring setup. Bleustein-Gulyaev SH surface acoustic waves waveguides were used as viscosity sensors. Application of SH surface acoustic waves in the liquid viscosity measurements at high pressure has many advantages. It enables viscosity measurement during phase transitions and in the high-pressure range where the classical viscosity measurement methods cannot operate. The knowledge of changes in viscosity in function of pressure and temperature can help to obtain a deeper insight into thermodynamic properties of liquids. Measurements of phase transition kinetics and viscosity of liquids at high pressures and various temperatures (isotherms) is a novelty.

Temperature measurement, Viscosity, Liquids, Ultrasonic variables measurement, Acoustic measurements, Pressure measurement, Acoustics

Determination of the mechanical and geometrical parameters of thin coatings and surface layers in materials is of great practical importance in engineering and technology. In this work the authors present a novel inversion procedure for simultaneous determination of thickness, shear elastic constant and density of thin coating layers in materials. The inversion procedure is based on measurements of the dispersion curve for Love surface acoustic waves. The inverse problem is formulated as an optimization problem with the appropriately designed objective function, depending on the material parameters of the coating layer, ultrasonic frequency, and the experimental data, i.e., measured phase velocity of the surface Love wave. The minimization of the objective function provides three parameters of a thin layer, i.e., its thickness, shear elastic constant and density. The agreement between the results of calculations with the proposed inversion method and the experimental data was good.

Inverse problems, Dispersion, Surface waves, Substrates, Copper, Coatings

Monitoring and studying the pressure effect on liquid properties are becoming increasingly important in food, chemical, cosmetic and pharmaceutical industry as well as in laboratory practice. Accurate thermodynamic data in liquids as a function of pressure are required for studies the structure of liquids as well as for various engineering applications. Direct measurement of thermodynamic parameters is very difficult. The velocity of sound is related to many thermodynamic parameters and can be measured relatively simple. In this work the variation of sound velocity and isothermal compressibility with hydrostatic pressure for triolein is evaluated up to 650 MPa. During the measurement we stated the phase transformation of triolein and the presence of the hysteresis of the dependence of sound velocity on pressure. To the authors' knowledge, the measurement of the sound velocity of liquids under high pressure during the phase transition is the novelty. From the performed measurements it results that the dependence of sound velocity on pressure can be used to investigate phase transformations in natural oils.

Vegetable oils, Velocity measurement, Phase measurement, Ultrasonic variables measurement, Thermodynamics, Liquids, Pressure measurement, Chemical industry, Monitoring, Pressure effects

The pressure change of viscosity of castor oil have been measured by ultrasonic method within the range of pressure up to 0.9 GPa. For the measurement, the authors have applied a new ultrasonic method based on Bleustein-Gulyaev (B-G) waves. For the lower pressures (up to 0.3 GPa) the results have been compared with earlier results obtained by falling body method, whereas for the higher pressure range results were compared with those obtained by the flow type viscometer. The measurements have shown: 1. Exponential rise of viscosity with pressure up to 0.4 GPa according to the Barus formula. 2. Extraordinary increment of viscosity at constant pressure during phase transition. 3. The decomposition of the high pressure phase during the decompression process have shown very large hysteresis of viscosity on pressure. 4. After the decompression process the viscosity lasts higher then a initial value for several hours.

Bleustein-Gulyaev (B-G) waves, high pressure, phase transitions, viscosity measurements

The high-pressure properties of triolein, a subject of extensive research at the Faculty of Physics of Warsaw University of Technology (WUT) has been enhanced by the results of viscosity measurements within the pressure range up to 0.8 GPa. For the measurement the authors have adopted a new ultrasonic method based on Bleustein-Gulyaev waves, successfully developed earlier for the low pressures in the Section of Acoustelectronics of the Institute of Fundamental Technological Research. The measurements have shown: 1) Exponential rise of viscosity with pressure up to 0.5 GPa. 2) Extraordinary increment of viscosity at constant pressure during phase transition. 3) Further exponential rise of viscosity with pressure of the high-pressure phase of triolein. 4) The pressure exponents of the viscosity of both phases were different (the high-pressure phase had much smaller exponent). 5) The decomposition of the high-pressure phase due to the slow-decompression has shown very large hysteresis of viscosity on pressure dependence.

Bleustein-Gulyaev (B-G) waves, high-pressure phase transitions, viscosity measurements, triolein

Measurement techniques for in-situ rheological investigations under high pressure allow insight into the phenomena governing the microstructural modifications. The conventional mechanical methods can not be operated to this aim due to their inherent limitations. This is why ultrasonic methods for the measurement of the viscosity of liquids under high pressure were introduced. To this end, the authors have applied new ultrasonic methods, i.e., the Love wave method and the Bleustein-Gulyaev (B-G) wave method. The measurements of the viscosity of liquid (castor oil) were carried out in function of hydrostatic pressure up to 800 MPa. During the measurement we stated the phase transformation of castor oil and the presence of the hysteresis of the dependence of viscosity on pressure. To the authors' knowledge, the measurement of the viscosity of liquids under high pressure during the phase transition and during the decompression process is the novelty.

Petroleum, Surface acoustic waves, Acoustic waves, Pressure measurement, Viscosity, Ultrasonic variables measurement, Liquids, Phase measurement, Measurement techniques, Rheology

The electro-elastic behavior of a viscoelastically loaded layered cylindrical resonator comprising of two coupled hollow cylinders is presented. The inner cylinder is piezoelectric. The outer cylinder is a non-piezoelectric (passive) metallic cylinder. Analytical formulas for the elements of the impedance matrix Z of a cylindrical piezoelectric resonator vibrating in a shear mode are established. Moreover, analytical formulas for the electrical admittance of a compound layered cylindrical resonator loaded with a viscoelastic liquid are established. Admittance diagrams obtained using: (1) a continuum electromechanical model; and (2) the elements of the impedance matrix Z are exactly the same. The analysis presented in this paper can be utilized for the design and construction of cylindrical piezoelectric viscosity sensors, annular accelerometers, filters, transducers and multi-layer resonators.

Viscosity, Elasticity, Chemical sensors, Piezoelectric materials, Admittance, Surface impedance, Mechanical sensors, Equations, Electromechanical sensors, Accelerometers

Analytical formulas for the elements of the impedance matrix Z of a cylindrical piezoelectric resonator vibrating in a shear mode are established. The input impedance was calculated employed the established elements of the impedance matrix Z. The analysis presented in this paper can be utilized for the design and construction of the cylindrical piezoelectric sensors, transducers and multi-layer resonators.

Surface impedance, Piezoelectric materials, Ceramics, Vibrations, Equations, Electromechanical sensors, Piezoelectric transducers, Mechanical sensors, Piezoelectric polarization, Viscosity

Despite the fact that Love surface waves have been discovered initially in seismology, as the waves occurring in the wake of earthquakes, they found recently numerous application in a benign domain of biosensors and chemosensors, following the pioneering works of P. Kiełczyński et. al. (1987-1989). Regardless of the fact that Love waves have been discovered over one hundred years ago (1911), there are still many interesting, fundamental problems about Love waves theory, their connections to other wave motions, etc., which remain unsolved. In this work, we analyze theoretically the properties of Love surface waves propagating in waveguides consisting of two different surface layers (upper and lower) deposited on a semi-infinite substrate. The upper surface of the waveguide is additionally covered with a semi-infinite layer of a Newtonian liquid occupying the half-space. In fact, the configuration of the waveguide represents a typical structure of the Love wave sensor, working in a liquid environment. By varying the viscosity of the Newtonian liquid covering the upper surface the waveguide, the authors have discovered a number of new intriguing phenomena displaying abrupt changing in Love wave parameters. In particular, for some selected values of the liquid viscosity, e.g., for η=11.9 Pas we have observed: 1) a dramatic change in the Love wave attenuation (approximately 15 times) and 2) a drastic change in the distribution of the mechanical displacement as a function of depth, i.e., the distance from the upper waveguide surface. This is accompanied by a pronounced redistribution of the power flow of the Love wave, i.e., the maximum of the power flow switches from the upper surface layer to the lower surface layer. To best of our knowledge, the above phenomena have not yet been reported in the scientific literature. The obtained results can be crucial in the design of Love wave sensors, as well as in seismology.

Love waves, viscoelastic liquids, layered waveguides, dispersion curves

Knowledge of high-pressure behavior of the processed liquids is necessary to control technological processes in many branches of industry (e.g., in chemical, pharmaceutical and food industries). However, data on high-pressure behavior of liquids are still incomplete. The aim of this study is to investigate the high-pressure behavior (i.e., thermopysical parameters and possible high-pressure phase transitions) of liquids (on the example of Camelina sativa oil), applying ultrasonic methods (i.e., sound velocity and parallel density measurements). Camelina sativa (false flax) oil has found application in many branches of industry as well as a raw material for biofuel production. Generally, conventional methods for measuring thermophysical properties of liquids fail at high pressures. The solution to the problem can be the use of ultrasonic methods. Ultrasonic measurements were performed at f = 5 MHz for pressures 0.1 - 660 MPa, and for temperatures 3 - 30 ºC. Pronounced high-pressure phase transitions were discovered by the authors in Camelina sativa oil. The use of ultrasonic methods has enabled the determination of many physicochemical parameters of Camelina sativa oil, such as: 1) adiabatic compressibility β_a, 2) thermal expansion coefficient α_p, 3) specific heat at constant pressure c_p, 4) thermal conductivity k and 5) thermal diffusivity a. The results obtained in this study are novel and can be employed to design and control technological processes in many branches of industry

Ultrasonic methods, high pressure, thermophysical properties, Camelina sativa

The aim of this work was to evaluate the impact of temperature and high pressure on thermophysical properties of liquids, exemplified by a Camelina sativa (false flax) oil. Camelina sativa oil has gained recently a growing interest due to its health-promoting effect as well as for its potential use in biodiesel production. To achieve the above objective, we measured the speed of sound and density in the selected oil. The speed of sound is directly associated to many thermophysical parameters of liquids. Hence, measurements of ultrasonic longitudinal wave velocity (f = 5 MHz) and liquid density, as a function of pressure and temperature, allowed determination of several important thermophysical parameters of the investigated liquid. The speed of sound in the liquid was determined from the time of flight measured with the cross-correlation method. To perform numerical calculations, it was helpful to introduce a Tammann–Tait type equation of state to approximate the measured density isotherms of the investigated Camelina sativa oil.

Speed of sound, high pressure, cross-correlation method, thermophysical parameters, Camelina sativa oil

It is very important from a practical point of view, to develop new and accurate methods of measuring the rheological parameters (viscosity η, elasticity μ and density ρ) of plastics and polymers. New materials require new methods of measuring their rheological parameters. To evaluate the rheological parameters of plastics so far mechanical methods are used. These methods are cumbersome, outdated and destructive. The use of SH (Shear Horizontal) surface Love waves, to evaluate rheological parameters of polymers, does not possess these disadvantages. The objective of this work is to establish a mathematical model of propagation of Love waves in layered elastic waveguides covered on their surface with viscoelastic materials described by different viscoelastic models, i.e., Kelvin-Voigt, Newton and Maxwell models. To this end, we developed a complex dispersion equation for Love waves propagating in loaded waveguides and performed numerical calculations.

Viscoelasticity, Love waves, Kelvin-Voigt model, Maxwell model, Complex dispersion equation

Progress in materials engineering has led to development of new materials with improved functional characteristics. One of the new types of materials introduced into industrial practice are plastics and polymers. These materials exhibit rheological (viscoelastic) properties, which combine simultaneously the properties of liquids and solids. Due to their attractive features, such as low specific weight, high resistance to chemical agents, cost effectiveness etc. these materials are widely used in chemical, automotive, aviation and space industry. Thus, it is very important to develop new, robust and accurate methods to measure the rheological parameters (viscosity η, elasticity μ and density ρ) of plastics and polymers. The conventional mechanical methods used so far to this end are outdated, time consuming, and cumbersome. To overcome this problems, the authors propose the use of ultrasonic methods that employ surface Love waves, what is a novelty.

Love waves, Rheological parameters, Rheological models, Polymers

Background, Motivation and Objective: In many industrial technological processes, liquids are subjected to high pressures, e.g., in the high pressure food preservation. Similarly, in modern fuel injection systems for diesel engines, biofuel is subjected to a pressure up to 300 MPa. In such conditions, in liquids, phase transitions can occur that substantially increase the density and liquid viscosity. This can be very detrimental for the engine or the technological equipment. Thus, it is important to determine at what pressures and temperatures phase transitions occur. Conventional mechanical methods for measuring physicochemical properties of liquids at these extreme conditions do not operate. By contrast, ultrasonic techniques are very suitable for measurements of physicochemical properties of liquids at high pressure, since they are non-destructive and can be fully automated. The aim of this work is to study the high-pressure physicochemical properties of liquids (exemplified by a camelina sativa - false flax oil) using novel ultrasonic methods.

High pressure, Biofuels, Viscosity, Phase transitions