Modelling of drying and rehydration of carrots using Peleg’s model

The drying and rehydration process of conventionally and organically cultivated carrots was studied and the resulting data were fitted to the Pelegs model. Carrots were fluid-bed and halogen dried and after that soaked in water at room temperature. The Pelegs model gave a good prediction of water removal and water uptake in all experiments (R>0,994). During the drying process the Pelegs rate constant (K₁) was affected by temperature. K₁ values decreased with the increase of the drying temperature. This relation was linear for fluid-bed drying and exponential for halogen drying, which implied a higher impact of the drying temperature on the dehydration kinetics during halogen drying. The lower K₁ values for fluid-bed drying suggested higher initial drying rates in comparison with halogen drying at all drying temperatures. The temperature dependence of 1/K₁ followed an Arrhenius-type relationship. Both Pelegs rehydration constants (K₁ and K₂) increased with the increase of the drying temperature. This implied regular decrease of initial rehydration rate and water uptake with the increase of the drying temperature.     

High-frequency transducers based on integrated piezoelectric thick films for medical imaging

A screen-printed PZT thick film with a final thickness of about 40 microm was deposited on a porous PZT substrate to obtain an integrated structure for ultrasonic transducer applications. This process makes it possible to decrease the number of steps in the fabrication of high-frequency, single-element transducers. The porous PZT substrates allow high acoustic impedance and attenuation to be obtained, satisfying transducer backing requirements for medical imaging. The piezoelectric thick films deliver high electromechanical performance, comparable to that of standard bulk ceramics (thickness coupling factor over 45%). Based on these structures, high-frequency transducers with a center frequency of about 25 MHz were produced and characterized. As a result, good sensitivity and axial resolution were obtained in comparison with similar transducers integrating a lead titanate (PT) disk as active material. The two transducers were integrated into a high-frequency imaging system, and comparative skin images are shown.     

A new approach for kinetic modeling and optimization of rubber molding

Although extensive research has been carried out on the understanding of the complex vulcanization process, the influence of reversion through exposure time and temperature on the vulcanization degree remains unclear. Therefore, the main aim of this study was a novel optimization approach that can help the industrial practitioners to select the optimal operating parameters, exposure time, and molding temperature, to achieve desired vulcanization degree of selected product. Spheres of four different diameters (2.5, 5, 10, and 20 cm) were selected as test geometry for simulation and optimization of rubber molding. Obtained vulcanization rheometer data for commercially available rubber blend (NR/SBR) were fitted by a new modeling approach, dividing vulcanization curve into two fitting sets: curing and reversion. The heat transfer equations for chosen geometry were coupled with proposed kinetic model. A new temperature-dependent kinetic parameter x, as the maximal reversion degree, was introduced, enabling determination of the lowest operating molding temperature (T_min = 132.36 °C), preventing high reversion and overheating of the rubber product. The final optimization goal was assessment of the optimal temperature and vulcanization time dependence on the rubber products dimensions. Proposed models have precise prediction with R² values greater than 0.8328 and MAPE less than 2.3099%.     

Water–based synthesis of La0,5Sr0,5CoO3 (LSCO) electrodes for ferroelectric thin films

Abstract

La_0,5Sr_0,5CoO₃ (LSCO) thin films were prepared from water solutions of lanthanum nitrate La(NO₃)₃x6H₂O, strontium nitrate Sr(NO₃)₂ and cobalt nitrate Co(NO₃)₂x6H₂O with different amounts of polyvinylalcohol (PVA). Thin films were deposited on platinum coated and thermally oxidized silicon substrates. The influence of the amount of PVA on the thermal decomposition of LSCO precursors, the surface wetting and the microstructure of LSCO thin films were investigated. The effort was also focused on the optimization of the thermal treatment to obtain dense LSCO thin films.     

Support Vector Machine State Estimation

The power system state estimator based on the support vector machine (SVM) and the weighted least squares (WLS) method is presented in the paper. The WLS provides state estimations necessary for creating SVM model which is then used for state estimation. The developed algorithm was tested on the IEEE systems, and the performance indicators were calculated in order to compare the accuracy of estimation and the measurement error filtering. The results indicate that the proposed hybrid model outperforms the classical WLS-based state estimation in terms of accuracy and improves measurement error filtering in comparison to the classical estimator.     

Adaptive neuro fuzzy estimation of underactuated robotic gripper contact forces

It is known that robotic manipulators are highly nonlinear systems, and an accurate mathematical model is difficult to obtain, thus making it difficult tо analyze with conventional analytical methods. Here, a novel design of an adaptive neuro fuzzy inference system (ANFIS) for estimation contact forces of a new adaptive gripper is presented. Since the conventional analytical methods is a very challenging task, fuzzy logic based systems are considered as potential candidates for such an application. The main points of this paper are in explanation of kinetostatic analyzing of the new gripper structure using rigid body model with added compliance in every single joint. The experimental results can be used as training data for ANFIS network for estimation of gripping forces. An adaptive neuro-fuzzy network is used to approximate correlation between contact point locations and contact forces magnitudes. The simulation results presented in this paper show the effectiveness of the developed method. This system is capable to find any change in ratio of positions of the gripper contacts and magnitudes of the contact forces and thus indicates state of both finger phalanges.     

Platinum deposition from hydrogen-ion beam irradiated solid precursor

We report a particular method of Pt/glassy carbon (GC) surface formation, based on a 15 keV H^+/? ion beam irradiation of thin H₂PtCl₆ × nH₂O layer placed over the GC surface. Hydrogen-ion beam irradiation provided an excellent adherence of Pt deposit, unlike to any other Pt-deposition method. Furthermore, the morphology and electrochemical activity of GC/Pt catalyst obtained at the fluence of 5 × 10¹⁷ cm^? 2 was found to be sensitive to the sign of charge of hydrogen ions. The electrochemical activity of such obtained Pt/GC surface toward oxygen reduction and ethanol oxidation was compared with the activity of the Pt deposits obtained by other more common reduction procedures.     

Functionality of chitosan-halloysite nanocomposite films for sustained delivery of antibiotics: The effect of chitosan molar mass

This study was designed to investigate functionality of tetracycline-loaded chitosan-halloysite nanocomposite films, with focus on evaluating the influence of chitosan molar mass on films applicability for sustained local antibiotic delivery. The films were prepared by casting and solvent evaporation using low, medium, and high molar mass chitosan. SEM analysis revealed compact, nonporous and rough surface of the nanocomposite films due to the presence of halloysite agglomerates and tetracycline crystals. Increasing chitosan molar mass led to higher values of elongation at break (from 21.65 ± 2.65 to 34.48 ± 2.34%), tensile strength (from 134.8 ± 13.21 to 246.36 ± 14.69 MPa), and elastic modulus (from 633.79 ± 128.37 to 716.55 ± 60.76 MPa) of the nanocomposite films. FT-IR, XRPD, and thermal analyses confirmed molar mass dependent chitosan-halloysite interactions and improved thermal stability of the nanocomposite films in comparison with chitosan films. The nanocomposite films released tetracycline in a sustained manner, with the slowest release achieved from the films consisting of low molar mass chitosan. Chitosan molar mass was confirmed to be a functionality-related characteristic of chitosan-halloysite nanocomposite films as potential sustained-release carriers for topical delivery of antibiotics. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48406.     

Mathematical model and digital simulation of pulsating overpotential copper electrodeposition

The relationships between the effective current density and the effective overpotential in copper electrodeposition carried out by pulsating overpotential have been analysed experimentally and by digital simulation on the basis of a simple mathematical model. The agreement between the theoretical and experimental results was satisfactory. The quality of the electrodeposit was also studied.     

Hubness-aware shared neighbor distances for high-dimensional k-nearest neighbor classification

Learning from high-dimensional data is usually quite challenging, as captured by the well-known phrase curse of dimensionality. Data analysis often involves measuring the similarity between different examples. This sometimes becomes a problem, as many widely used metrics tend to concentrate in high-dimensional feature spaces. The reduced contrast makes it more difficult to distinguish between close and distant points, which renders many traditional distance-based learning methods ineffective. Secondary distances based on shared neighbor similarities have recently been proposed as one possible solution to this problem. However, these initial metrics failed to take hubness into account. Hubness is a recently described aspect of the dimensionality curse, and it affects all sorts of $k$ -nearest neighbor learning methods in severely negative ways. This paper is the first to discuss the impact of hubs on forming the shared neighbor similarity scores. We propose a novel, hubness-aware secondary similarity measure $simhub_s$ and an extensive experimental evaluation shows it to be much more appropriate for high-dimensional data classification than the standard $simcos_s$ measure. The proposed similarity changes the underlying $k$ NN graph in such a way that it reduces the overall frequency of label mismatches in $k$ -neighbor sets and increases the purity of occurrence profiles, which improves classifier performance. It is a hybrid measure, which takes into account both the supervised and the unsupervised hubness information. The analysis shows that both components are useful in their own ways and that the measure is therefore properly defined. This new similarity does not increase the overall computational cost, and the improvement is essentially ‘free’.